Gene Summary

Gene:ABL1; ABL proto-oncogene 1, non-receptor tyrosine kinase
Aliases: ABL, JTK7, p150, c-ABL, v-abl, c-ABL1, bcr/abl
Summary:This gene is a protooncogene that encodes a protein tyrosine kinase involved in a variety of cellular processes, including cell division, adhesion, differentiation, and response to stress. The activity of the protein is negatively regulated by its SH3 domain, whereby deletion of the region encoding this domain results in an oncogene. The ubiquitously expressed protein has DNA-binding activity that is regulated by CDC2-mediated phosphorylation, suggesting a cell cycle function. This gene has been found fused to a variety of translocation partner genes in various leukemias, most notably the t(9;22) translocation that results in a fusion with the 5' end of the breakpoint cluster region gene (BCR; MIM:151410). Alternative splicing of this gene results in two transcript variants, which contain alternative first exons that are spliced to the remaining common exons. [provided by RefSeq, Aug 2014]
Databases:VEGA, OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:tyrosine-protein kinase ABL1
Source:NCBIAccessed: 15 March, 2017


What does this gene/protein do?
Show (48)
Pathways:What pathways are this gene/protein implicaed in?
Show (6)

Cancer Overview

Alterations of the ABL1 protooncogene by chromosomal rearrangements, particularly t(9;22) translocations, or by viral transductions are implicated in haematological malignancies. The t(9;22) translocation is present in over 90% of chronic myelogeneous leukaemia cases. This translocation causes the "head to tail" fusion of the BCR and ABL genes. t(9;22) translocations are also present (though less common) in acute lymphoblastic leukaemia.

Research Indicators

Publications Per Year (1992-2017)
Graph generated 15 March 2017 using data from PubMed using criteria.

Literature Analysis

Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic.

  • Philadelphia Chromosome
  • ABL1
  • Survival Rate
  • Signal Transduction
  • Reproducibility of Results
  • Chronic Myelogenous Leukemia
  • Epidermal Growth Factor Receptor
  • BCR
  • Up-Regulation
  • Sequence Deletion
  • Pyrimidines
  • Acute Myeloid Leukaemia
  • Receptors, Cytokine
  • Protein Kinase Inhibitors
  • Proto-Oncogene Proteins c-fyn
  • Protein Structure, Tertiary
  • Vitamin E
  • Prostate Cancer
  • Yttrium Radioisotopes
  • Transcriptome
  • Reverse Transcription
  • Fusion Proteins, bcr-abl
  • Chromosome 9
  • United States Food and Drug Administration
  • Young Adult
  • Stem Cell Niche
  • Reference Standards
  • beta Catenin
  • Single Nucleotide Polymorphism
  • Risk Factors
  • Withholding Treatment
  • Slovakia
  • Transcription
  • Messenger RNA
  • Mutation
  • Triazoles
  • Sarcoma, Myeloid
  • DNA Sequence Analysis
  • TOR Serine-Threonine Kinases
  • T-Lymphocytes, Cytotoxic
  • Tumor Stem Cell Assay
  • Acute Lymphocytic Leukaemia
Tag cloud generated 15 March, 2017 using data from PubMed, MeSH and CancerIndex

Specific Cancers (3)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Entity Topic PubMed Papers
Acute Lymphocytic Leukaemia (ALL)NUP214-ABL1 rearrangements in T-Cell Acute Lymphoblastic Leukemia
The NUP214-ABL1 gene is the second most prevalent fusion gene involving ABL1 in malignant hemopathies, with a frequency of 5% in T-cell ALL. (De Braekeleer et al, 2011)
View Publications39
Chronic Myelogenous LeukemiaBCR-ABL Translocation in Chronic Myeloid Leukaemia
The t(9;22)(q34;q11) "Philadelphia" translocation is characteristic of chronic myeloid leukaemia (CML). The translocation results in the "head to tail" fusion of the BCR and ABL1 genes and is present in over 90% of CML cases.
See: More details below...
Acute Lymphocytic Leukaemia (ALL)BCR-ABL Translocation in Acute Lymphoblastic Leukaemia
See: More details below...

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

BCR-ABL Translocation in Chronic Myeloid Leukaemia

The t(9;22)(q34;q11) "Philadelphia" translocation is characteristic of chronic myeloid leukaemia (CML). The translocation results in the "head to tail" fusion of the BCR and ABL1 genes and is present in over 90% of CML cases.

See also: Chronic Myeloid Leukemia (CML) - Clinical and Research information
See also: BCR.htm gene

Latest Publications

Lu Y, Li Y, Chai X, et al.
Long noncoding RNA HULC promotes cell proliferation by regulating PI3K/AKT signaling pathway in chronic myeloid leukemia.
Gene. 2017; 607:41-46 [PubMed] Related Publications
Aberrant expression of long noncoding RNA (lncRNA) HULC is associated with various human cancers. However, the role of HULC in chronic myeloid leukemia (CML) is unknown. In this study, we found that HULC was remarkably overexpressed in both leukemia cell lines and primary hematopoietic cells derived from CML patients. The increase in HULC expression was positively correlated with clinical stages in CML. Moreover, the knockdown of HULC significantly inhibited CML cell proliferation and induced apoptosis by repressing c-Myc and Bcl-2. Furthermore, inhibition of HULC enhanced imatinib-induced apoptosis of CML cells. Further experiments demonstrated that HULC silencing markedly suppressed the phosphorylation of PI3K and AKT, indicating that enhancement of imatinib-induced apoptosis by HULC inhibition is related with the reduction of c-Myc expression and inhibition of PI3K/Akt pathway activity. Furthermore, HULC could modulate c-Myc and Bcl-2 by miR-200a as an endogenous sponge. Taken together, these results reveal that HULC promotes oncogenesis in CML and suggest a potential strategy for the CML treatment.

Ahmad HM, Muiwo P, Muthuswami R, Bhattacharya A
FosB regulates expression of miR-22 during PMA induced differentiation of K562 cells to megakaryocytes.
Biochimie. 2017; 133:1-6 [PubMed] Related Publications
Expression of many miRNAs is altered in different cancers and these changes are thought to play a key role in formation and progression of cancer. In chronic myelogenous leukemia (CML) a number of miRNAs are known to be down regulated as compared to normal cells. In this report we have investigated the mechanism of this down regulation by using PMA induced differentiation of CML cell line K562 to megakaryocytes as an experimental system. On treatment with PMA, expression of many down regulated miRNAs including miR-22 is induced. PMA also induces expression of several transcription factors, including FosB, EGR1 and EGR2. Our results using a number of approaches, such as promoter reporter assay, FosB knock down and Chip assay, suggest that the expression of miR-22 is regulated transcriptionally by FosB.

Farhadi E, Zaker F, Safa M, Rezvani MR
miR-101 sensitizes K562 cell line to imatinib through Jak2 downregulation and inhibition of NF-κB target genes.
Tumour Biol. 2016; 37(10):14117-14128 [PubMed] Related Publications
Imatinib mesylate (IM) is a frontline treatment in the early chronic phase of chronic myeloid leukemia (CML). However, intrinsic and acquired resistance against this drug has been defined and this issue has become a problem and a challenge in CML treatment. According to new findings, the inhibition of Janus kinase 2 (Jak2) in Bcr-Abl+ cells can promote apoptosis in IM-resistant cells. microRNAs (miRNAs) regulate the gene expression by targeting the messenger RNA (mRNA) for degradation. Recently, a growing body of evidence has implicated that dysregulation of miRNAs is associated with cancer initiation and development. In this report, we proposed that miRNA-101 targets Jak2 mRNA and regulates its expression and induces K562 leukemia cell apoptosis. Here, we transduced the K562 cell line with a miR-101-overexpressing vector and evaluated the Jak2 mRNA level. Our results showed that miR-101 overexpression in Bcr-Abl+ cells reduced the Jak2 mRNA level. Moreover, imatinib treatment and miR-101 upregulation led to miR-23a overexpression, which has putative binding site(s) on 3'-untranslated regions (3'-UTRs) of STAT5, CCND1, and Bcl-2 genes. Our results also indicated that miR-101 overexpression inhibited cell proliferation indicated by the MTT assay and promoted apoptosis detected via flow cytometry. Importantly, mRNA expression of NF-kappa B-regulated anti-apoptotic (Bcl-2, Bcl-xl, MCL-1, XIAP, and survivin) and proliferative (c-Myc and CCND1) genes was decreased. These findings suggest that miR-101 acts as a tumor suppressor by downregulating Jak2 expression and sensitizing K562 cells to imatinib. Therefore, restoration of miR-101 may be a therapeutic approach for CML treatment.

Ji M, Hur M, Kim HN, et al.
Presence of Additional Cytogenetic Abnormality of t(1;15) at Diagnosis of Chronic Myelogenous Leukemia-Chronic Phase.
Ann Clin Lab Sci. 2016; 46(3):308-11 [PubMed] Related Publications
At diagnosis, fewer than 10% of chronic myelogenous leukemia (CML) patients have additional cytogenetic abnormalities (ACAs), which are frequently found in transformation to blast crisis. We report a case of CML-chronic phase (CML-CP) that showed t(1;15) at diagnosis. A 64-year-old man presented with sustained leukocytosis and thrombocytosis. His bone marrow (BM) was hypercellular with 2.5% blasts and BCR-ABL1 rearrangement. The karyotype in the BM was 46,XY,t(1;15)(q32;p13),t(9;22)(q34;q11.2)[20], while the karyotype in the peripheral blood was 46,XY[20]. This is the first report on the presence of t(1;15) at diagnosis of CML-CP, and its clinical significance remains unclear.

Al-Achkar W, Moassass F, Youssef N, Wafa A
Correlation of p210 BCR-ABL transcript variants with clinical, parameters and disease outcome in 45 chronic myeloid leukemia patients.
J BUON. 2016 Mar-Apr; 21(2):444-9 [PubMed] Related Publications
PURPOSE: The aim of this study was to search the BCR/ABL 1 fusion gene in 45 chronic myeloid leukemia (CML) Syrian patients using nested reverse transcription polymerase chain reaction (RT-PCR) and compare our results with those of conventional cytogenetics and molecular cytogenetics methods.
METHODS: 45 bone marrow or peripheral blood samples from untreated CML patients in chronic phase (CP) were obtained at diagnosis, and analyzed by nested RT-PCR, conventional cytogenetics and molecular cyto-genetics methods.
RESULTS: 45 patients examined were positive for some type of BCR/ABL1 fusion gene rearrangement. Out of 45 studied CML patients, 23 (51.1%) expressed b3a2 fusion transcript, 21 (46.7%) b2a2 transcript, and 1 (2.2%) a rare b2a3 transcript. No patient co-expressed both b3a2/b2a2 types.
CONCLUSIONS: The distribution BCR-ABL1 transcript types found in Syria were similar to that of Indian Far-Eastern, African or European populations and the M-BCR rearrangement types were not dependent on white blood count (WBC), platelet count, hemoglobin level or gender of the patients. Overall, we could show that patients with b3a2 rearrangements were younger than patients with b2a2 transcripts, thus our young patients may have a worse prognosis.

Kang ZJ, Liu YF, Xu LZ, et al.
The Philadelphia chromosome in leukemogenesis.
Chin J Cancer. 2016; 35:48 [PubMed] Free Access to Full Article Related Publications
The truncated chromosome 22 that results from the reciprocal translocation t(9;22)(q34;q11) is known as the Philadelphia chromosome (Ph) and is a hallmark of chronic myeloid leukemia (CML). In leukemia cells, Ph not only impairs the physiological signaling pathways but also disrupts genomic stability. This aberrant fusion gene encodes the breakpoint cluster region-proto-oncogene tyrosine-protein kinase (BCR-ABL1) oncogenic protein with persistently enhanced tyrosine kinase activity. The kinase activity is responsible for maintaining proliferation, inhibiting differentiation, and conferring resistance to cell death. During the progression of CML from the chronic phase to the accelerated phase and then to the blast phase, the expression patterns of different BCR-ABL1 transcripts vary. Each BCR-ABL1 transcript is present in a distinct leukemia phenotype, which predicts both response to therapy and clinical outcome. Besides CML, the Ph is found in acute lymphoblastic leukemia, acute myeloid leukemia, and mixed-phenotype acute leukemia. Here, we provide an overview of the clinical presentation and cellular biology of different phenotypes of Ph-positive leukemia and highlight key findings regarding leukemogenesis.

Gutiérrez-Malacatt H, Ayala-Sanchez M, Aquino-Ortega X, et al.
The rs61764370 Functional Variant in the KRAS Oncogene is Associated with Chronic Myeloid Leukemia Risk in Women.
Asian Pac J Cancer Prev. 2016; 17(4):2265-70 [PubMed] Related Publications
BACKGROUND: Chronic myeloid leukemia (CML) is one of the most frequent hematopoietic malignancies in the elderly population; however, knowledge is limited regarding the genetic factors associated with increased risk for CML. Polymorphisms affecting microRNA (miRNA) biogenesis or mRNA:miRNA interactions are important risk factors in the development of different types of cancer. Thus, we carried out a case-control study to test the association with CML susceptibility of gene variants located in the miRNA machinery genes AGO1 (rs636832) and GEMIN4 (rs2740348), as well as in the miRNA binding sites of the genes BRCA1 (rs799917) and KRAS (rs61764370).
MATERIALS AND METHODS: We determined the genotype of 781 Mexican-Mestizo individuals (469 healthy subjects and 312 CML cases) for the four polymorphisms using TaqMan probes to test the association with CML susceptibility.
RESULTS: We found a borderline association of the minor homozygote genotype of the KRAS_rs61764370 polymorphism with an increased risk for CML susceptibility (P = 0.06). After gender stratification, this association was significant only for women (odds ratio [OR] = 13.41, P = 0.04). The distribution of the allelic and genotypic frequencies of the four studied SNPs was neither associated with advanced phases of CML nor treatment response.
CONCLUSIONS: To the best of our knowledge, this study is the first to show a significant association of the KRAS_rs61764370 SNP with CML. To further determine such an association of with CML susceptibility, our results must be replicated in different ethnic groups.

Cordeiro M, Giestas L, Lima JC, Baptista PM
BioCode gold-nanobeacon for the detection of fusion transcripts causing chronic myeloid leukemia.
J Nanobiotechnology. 2016; 14(1):38 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Gold-nanobeacons (Au-nanobeacons) have proven to be versatile systems for molecular diagnostics and therapeutic actuators. Here, we present the development and characterization of two gold nanobeacons combined with Förster resonance energy transfer (FRET) based spectral codification for dual mode sequence discrimination. This is the combination of two powerful technologies onto a single nanosystem.
RESULTS: We proved this concept to detect the most common fusion sequences associated with the development of chronic myeloid leukemia, e13a2 and e14a2. The detection is based on spectral shift of the donor signal to the acceptor, which allows for corroboration of the hybridization event. The Au-nanobeacon acts as scaffold for detection of the target in a homogenous format whose output capability (i.e. additional layer of information) is potentiated via the spectral codification strategy.
CONCLUSIONS: The spectral coded Au-nanobeacons permit the detection of each of the pathogenic fusion sequences, with high specificity towards partial complementary sequences. The proposed BioCode Au-nanobeacon concept provides for a nanoplatform for molecular recognition suitable for cancer diagnostics.

Ohyashiki K, Umezu T, Katagiri S, et al.
Downregulation of Plasma miR-215 in Chronic Myeloid Leukemia Patients with Successful Discontinuation of Imatinib.
Int J Mol Sci. 2016; 17(4):570 [PubMed] Free Access to Full Article Related Publications
Approximately 40% of chronic myeloid leukemia (CML) patients who discontinue imatinib (IM) therapy maintain undetectable minimal residual disease (UMRD) for more than one year (stopping IM (STOP-IM)). To determine a possible biomarker for STOP-IM CML, we examined plasma miRNA expression in CML patients who were able to discontinue IM. We first screened candidate miRNAs in unselected STOP-IM patients, who had sustained UMRD after discontinuing IM for more than six months, in comparison with healthy volunteers, by using a TaqMan low-density array for plasma or exosomes. Exosomal miR-215 and plasma miR-215 were downregulated in the STOP-IM group compared to the control, indicating that the biological relevance of the plasma miR-215 level is equivalent to that of the exosomal level. Next, we performed real-time quantitative RT-PCR in 20 STOP-IM patients, 32 patients with UMRD on continued IM therapy (IM group) and 28 healthy volunteers. The plasma miRNA-215 level was significantly downregulated in the STOP-IM group (p < 0.0001); we determined the cut-off level and divided the IM group patients into two groups according to whether the plasma miR-215 was downregulated or not. The IM group patients with a low plasma miR-215 level had a significantly higher total IM intake, compared to the patients with elevated miR-215 levels (p = 0.0229). Functional annotation of miR-215 target genes estimated by the Database for Annotation, Visualization and Integrated Discovery (DAVID) bioinformatic tools involved cell cycle, mitosis, DNA repair and cell cycle checkpoint. Our study suggests a possible role of miR-215 in successful IM discontinuation.

Pineda G, Lennon KM, Delos Santos NP, et al.
Tracking of Normal and Malignant Progenitor Cell Cycle Transit in a Defined Niche.
Sci Rep. 2016; 6:23885 [PubMed] Free Access to Full Article Related Publications
While implicated in therapeutic resistance, malignant progenitor cell cycle kinetics have been difficult to quantify in real-time. We developed an efficient lentiviral bicistronic fluorescent, ubiquitination-based cell cycle indicator reporter (Fucci2BL) to image live single progenitors on a defined niche coupled with cell cycle gene expression analysis. We have identified key differences in cell cycle regulatory gene expression and transit times between normal and chronic myeloid leukemia progenitors that may inform cancer stem cell eradication strategies.

Yi YJ, Jia XH, Wang JY, et al.
Knockdown of HOXA10 reverses the multidrug resistance of human chronic mylogenous leukemia K562/ADM cells by downregulating P-gp and MRP-1.
Int J Mol Med. 2016; 37(5):1405-11 [PubMed] Related Publications
Multidrug resistance (MDR) of leukemia cells is a major obstacle in chemotherapeutic treatment. The high expression and constitutive activation of P-glycoprotein (P-gp) and multidrug resistance protein-1 (MRP-1) have been reported to play a vital role in enhancing cell resistance to anticancer drugs in many tumors. The present study aimed to investigate the reversal of MDR by silencing homeobox A10 (HOXA10) in adriamycin (ADR)-resistant human chronic myelogenous leukemia (CML) K562/ADM cells by modulating the expression of P-gp and MRP-1. K562/ADM cells were stably transfected with HOXA10-targeted short hairpin RNA (shRNA). The results of reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blot analysis showed that the mRNA and protein expression of HOXA10 was markedly suppressed following transfection with a shRNA-containing vector. The sensitivity of the K562/ADM cells to ADR was enhanced by the silencing of HOXA10, due to the increased intracellular accumulation of ADR. The accumulation of ADR induced by the silencing of HOXA10 may be due to the downregulation of P-gp and MRP-1. Western blot analysis revealed that downregulating HOXA10 inhibited the protein expression of P-gp and MRP-1. Taken together, these results suggest that knockdown of HOXA10 combats resistance and that HOXA10 is a potential target for resistant human CML.

Eyüpoğlu D, Bozkurt S, Haznedaroğlu İ, et al.
The Impact of Variant Philadelphia Chromosome Translocations on the Clinical Course of Chronic Myeloid Leukemia.
Turk J Haematol. 2016; 33(1):60-5 [PubMed] Free Access to Full Article Related Publications
Chronic myeloid leukemia (CML) is genetically characterized by the presence of the reciprocal translocation t(9;22) with the formation of Philadelphia (Ph) chromosome. Sometimes, the Ph translocation is generated by variant rearrangements. The prognostic impact of the variant translocations is still controversial. Among the 180 patients with Ph-positive CML who were treated in Hacettepe University Faculty of Medicine Division of Hematology, variant translocations were detected, and retrospectively clinical and prognostic features were described. Also we performed a comprehensive literature review on the prognosis of such variant cases before and after tyrosine kinase inhibitor era. Five patients (2.7%) had variant Ph chromosomes, involved in the rearrangements were chromosomes 2 (2 cases), 11, 14 and 15. Patients were treated with imatinib or dasatinib. All patients reached a stable major molecular response suggesting a prognosis not worse than standard translocation individuals. Our present data were compatible with the data of previous studies indicating no difference in the prognosis between standard and variant translocations in tyrosine kinase inhibitors era of CML.

Zheng Q, Cao J, Hamad N, et al.
Single nucleotide polymorphisms in apoptosis pathway are associated with response to imatinib therapy in chronic myeloid leukemia.
J Transl Med. 2016; 14:82 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: The mechanism of action of imatinib is known to involve the Fas-mediated apoptosis pathway. Consequently inter-individual variations in this apoptosis pathway might be associated with imatinib response or resistance.
METHODS: This study attempted to focus on eight genotypes in the apoptosis pathway including FAS (rs1800682, rs2229521, rs2234767 and rs2234978), FASLG (rs763110), CASP10 (rs13006529), and APAF1 (rs1439123, rs2288713) and analyzed their association with treatment outcomes including molecular response with 4.5 log reduction (MR4.5), following imatinib therapy in 187 Korean CML patients.
RESULTS: The GG/GA genotype in FAS (rs2234767) showed a higher rate of MR4.5 than the AA genotype (at 5 years 59.7 vs 37.4 %, p = 0.013). Using a bootstrap procedure for internal validation we confirmed that FAS (rs2234767) correlates with MR4.5 (p = 0.050). Multivariate analysis confirmed that the FAS genotype (rs2234767) is an independent surrogate for MR4.5 (p = 0.019, HR 0.43, 95 % CI [0.22-0.87]).
CONCLUSIONS: The Fas/FasL signaling pathway may represent the major pathway that mediates apoptosis in CML treated with imatinib. SNP markers in the apoptosis pathway including FAS genotype (rs2234767) can be potential surrogates for predicting deeper molecular response after imatinib therapy.

Gorre M, Mohandas PE, Kagita S, et al.
Significance of ATM Gene Polymorphisms in Chronic Myeloid Leukemia - a Case Control Study from India.
Asian Pac J Cancer Prev. 2016; 17(2):815-21 [PubMed] Related Publications
BACKGROUND: Development of chronic myeloid leukemia (CML) involves formation of double strand breaks (DSBs) which are initially sensed by the ataxia telangiectasia mutated (ATM) signal kinase to induce a DNA damage response (DDR). Mutations or single nucleotide polymorphisms in ATM gene are known to influence the signaling capacity resulting in susceptibility to certain genetic diseases such as cancers.
MATERIALS AND METHODS: In the present study, we have analyzed -5144A>T (rs228589) and C4138T (rs3092856) polymorphisms of theATM gene through polymerase chain reaction- restriction fragment length polymorphism (PCR-RFLP) in 925 subjects (476 CML cases and 449 controls).
RESULTS: The A allele of -5144A>T polymorphism and T allele of C4138T polymorphism which were known to be influencing ATM signaling capacity are significantly associated with enhanced risk for CML independently and also in combination (evident from the haplotype and diplotype analyses). Significant elevation in the frequencies of both the risk alleles among high risk groups under European Treatment and Outcome Study (EUTOS) score suggests the possible role of these polymorphisms in predicting the prognosis of CML patients.
CONCLUSIONS: This study provides the first evidence of association of functional ATM gene polymorphisms with the increased risk of CML development as well as progression.

Limsuwanachot N, Siriboonpiputtana T, Karntisawiwat K, et al.
Multiplex RT-PCR Assay for Detection of Common Fusion Transcripts in Acute Lymphoblastic Leukemia and Chronic Myeloid Leukemia Cases.
Asian Pac J Cancer Prev. 2016; 17(2):677-84 [PubMed] Related Publications
BACKGROUND: Acute lymphoblastic leukemia (ALL) is a heterogeneous disease which requires a risk-stratified approach for appropriate treatment. Specific chromosomal translocations within leukemic blasts are important prognostic factors that allow identification of relevant subgroups. In this study, we developed a multiplex RT-PCR assay for detection of the 4 most frequent translocations in ALL (BCR-ABL, TEL-AML1, MLL-AF4, and E2A- PBX1).
MATERIALS AND METHODS: A total of 214 diagnosed ALL samples from both adult and pediatric ALL and 14 cases of CML patients (154 bone marrow and 74 peripheral blood samples) were assessed for specific chromosomal translocations by cytogenetic and multiplex RT-PCR assays.
RESULTS: The results showed that 46 cases of ALL and CML (20.2%) contained the fusion transcripts. Within the positive ALL patients, the most prevalent cryptic translocation observed was mBCR-ABL (p190) at 8.41%. In addition, other genetic rearrangements detected by the multiplex PCR were 4.21% TEL-AML1 and 2.34% E2A-PBX1, whereas MLL-AF4 exhibited negative results in all tested samples. Moreover, MBCR-ABL was detected in all 14 CML samples. In 16 samples of normal karyotype ALL (n=9), ALL with no cytogentic result (n=4) and CML with no Philadelphia chromosome (n=3), fusion transcripts were detected.
CONCLUSIONS: Multiplex RT-PCR provides a rapid, simple and highly sensitive method to detect fusion transcripts for prognostic and risk stratification of ALL and CML patients.

Liu LJ, Cao XJ, Zhou C, et al.
Construction of polycythemia vera protein interaction network and prediction of related biological functions.
Genet Mol Res. 2016; 15(1) [PubMed] Related Publications
Here, polycythemia vera (PV)-related genes were screened by the Online Mendelian Inheritance in Man (OMIM), and literature pertaining to the identified genes was extracted and a protein-protein interaction network was constructed using various Cytoscape plugins. Various molecular complexes were detected using the Clustervize plugin and a gene ontology-enrichment analysis of the biological pathways, molecular functions, and cellular components of the selected molecular complexes were identified using the BiNGo plugin. Fifty-four PV-related genes were identified in OMIM. The protein-protein interaction network contains 5 molecular complexes with correlation integral values >4. These complexes regulated various biological processes (peptide tyrosinase acidification, cell metabolism, and macromolecular biosynthesis), molecular functions (kinase activity, receptor binding, and cytokine activity), and the cellular components were mainly concentrated in the nucleus, intracellular membrane-bounded organelles, and extracellular region. These complexes were associated with the JAK-STAT signal transduction pathway, neurotrophic factor signaling pathway, and Wnt signaling pathway, which were correlated with chronic myeloid leukemia and acute myeloid leukemia.

Kokate P, Dalvi R, Mandava S
A complex three-way translocation with deletion of the TP53 gene in a blast crisis chronic myeloid leukemia patient.
J Cancer Res Ther. 2015 Oct-Dec; 11(4):1037 [PubMed] Related Publications
Chronic myeloid leukemia (CML) is characterized by the Philadelphia (Ph) chromosome created by the reciprocal translocation t(9;22) (q34;q11), resulting in the chimeric BCR-ABL oncogene. Variant Ph' chromosome translocations involving additional chromosomes are seen in 5-10% of CML cases. In the present study, a novel case of Ph' chromosome-positive CML is reported, with a three-way translocation involving chromosomal regions, 9q34, 22q11.2 and 17p11.2, with additional secondary changes. The three-way translocation has resulted in a deletion of the TP53 gene located on the chromosome 17p13.1 locus. Deletion of the TP53 gene may be a major contributing factor in the development of resistance to imatinib and blast crisis.

Alikian M, Ellery P, Forbes M, et al.
Next-Generation Sequencing-Assisted DNA-Based Digital PCR for a Personalized Approach to the Detection and Quantification of Residual Disease in Chronic Myeloid Leukemia Patients.
J Mol Diagn. 2016; 18(2):176-89 [PubMed] Related Publications
Recent studies indicate that 40% of chronic myeloid leukemia patients who achieve sustained undetectable BCR-ABL1 transcripts on tyrosine kinase inhibitor therapy remain disease-free after drug discontinuation. In contrast, 60% experience return of detectable disease and have to restart treatment, thus highlighting the need for an improved method of identifying patients with the lowest likelihood of relapse. Here we describe the validation of a personalized DNA-based digital PCR (dPCR) approach for quantifying very low levels of residual disease, which involves the rapid identification of t(9;22) fusion junctions using targeted next-generation sequencing coupled with the use of a dPCR platform. t(9;22) genomic breakpoints were successfully mapped in samples from 32 of 32 patients with early stage disease. Disease quantification by DNA-based dPCR was performed using the Fluidigm BioMark platform on 46 follow-up samples from 6 of the 32 patients, including 36 samples that were in deep molecular remission. dPCR detected persistent disease in 81% of molecular-remission samples, outperforming both RT-dPCR (25%) and DNA-based quantitative PCR (19%). We conclude that dPCR for BCR-ABL1 DNA is the most sensitive available method of residual-disease detection in chronic myeloid leukemia and may prove useful in the management of tyrosine kinase inhibitor withdrawal.

Li C, Yichao J, Jiaxin L, et al.
Methylenetetrahydrofolate reductase gene polymorphism and risk of chronic myelogenous leukemia: a meta-analysis.
J BUON. 2015 Nov-Dec; 20(6):1534-45 [PubMed] Related Publications
PURPOSE: Reported evidence supports a role for methylenetetrahydrofolate reductase (MTHFR) in the risk of chronic myelogenous leykemia (CML). However, these reports arrived at non-conclusive and even conflicting results regarding the association between two common MTHFR polymorphisms (C677T and A1298C) and CML risk. Thus, a meta-analysis was carried out to clarify a more precise association between these two polymorphisms and the CML risk by updating the available publications.
METHODS: Pooled odds ratios (OR) with corresponding 95% confidence interval (95% CI) and stratification analysis were performed to estimate the relationship between MTHFR polymorphisms and the risk of CML under different genetic comparison models.
RESULTS: Data from the meta-analysis showed no significant association between MTHFR C677T polymorphism and CML risk. However, significant associations were found between MTHFR A1298C variants and CML risk under homozygous comparison model (CC vs AA, OR=1.62, 95% CI=1.11-2.36, p=0.01) and dominant comparison model (CC+AC vs AA, OR=1.68, 95% CI=1.17-2.43, p=0.005) in overall population; especially more obvious impacts were noticed for Asian populations in subgroup analysis for homozygous model (CC vs AA, OR=2.00, 95% CI=1.25-3.21, p=0.004) and dominant model (CC+AC vs AA, OR=2.49, 95% CI=1.42-4.36, p=0.001), but this did not apply in Caucasian populations.
CONCLUSION: The results of this meta-analysis suggested no significant association between MTHFR C677T polymorphism and CML risk, while an increased CML risk was noticed for 1298C variant carriers, especially in Asian populations but not in Caucasian populations, which suggested ethnicity differences between MTHFR A1298C polymorphisms and risk of CML.

Liu B, Zhang W, Ma H
Complete cytogenetic response to Nilotinib in a chronic myeloid leukemia case with a rare e13a3(b2a3) BCR-ABL fusion transcript: A case report.
Mol Med Rep. 2016; 13(3):2635-8 [PubMed] Related Publications
In the present study, an atypical case of chronic myeloid leukemia (CML) in a 32-year-old male was reported. CML cases with e13a3 breakpoint cluster region (BCR)-ABL transcripts are extremely rare. Reverse transcription quantitative‑polymerase chain reaction (RT-qPCR) was initially negative due to the primer corresponding to ABL a2 sequences and diagnosis was based upon analysis of the bone marrow smear, fluorescence in situ hybridization and karyotype analysis. RT‑qPCR analysis with the ABL primer, which was located in ABL exon 3 to enable the detection of fusions with either ABL a2 or exon a3 demonstrated the presence of the BCR‑ABL fusion transcript e13a3. The patient responded well to Nilotinib and achieved a complete cytogenetic response after 3 months.

BCR-ABL Translocation in Acute Lymphoblastic Leukaemia

See also: BCR.htm gene

Latest Publications

Zhang W, Kuang P, Li H, et al.
Prognostic significance of IKZF1 deletion in adult B cell acute lymphoblastic leukemia: a meta-analysis.
Ann Hematol. 2017; 96(2):215-225 [PubMed] Related Publications
The IKAROS family zinc finger 1 (IKZF1) gene is frequently altered in adults with B cell acute lymphoblastic leukemia (ALL). Although many studies have indicated that IKZF1 alterations might be associated with poor outcomes in adults with ALL, the results remain controversial. A previous meta-analysis demonstrated the negative prognostic significance of IKZF1 deletion in ALL. However, most of the included studies (14 out of 15) were conducted in pediatric patients with ALL, and age was identified as a significant source of heterogeneity. Thus, performing the present meta-analysis provides valuable information to further elucidate the prognostic value of IKZF1 deletion in adults with ALL. Eight studies were identified that had been published prior to August 1, 2016. The studies included a total of 1008 patients. Hazard ratios (HRs) with 95% confidence intervals (CIs) of overall survival (OS) and disease-free survival (DFS)/relapse-free survival (RFS)/progression-free survival (PFS)/event-free survival (EFS) were pooled to estimate the prognostic power of IKZF1 deletion. Pooled HRs suggested that IKZF1 deletion had a negative impact on both OS (HR = 1.40, 95% CI 1.13-1.73) and DFS/RFS/PFS/EFS (HR = 1.67, 95% CI 1.28-2.17) in the overall population. Subgroup analyses indicated that IKZF1 deletion could independently predict unfavorable OS (HR = 1.60, 95% CI 1.25-2.06) and DFS/RFS/PFS/EFS (HR = 1.67, 95% CI 1.28-2.17) in BCR-ABL1-negative but not in BCR-ABL1-positive B cell ALL patients. Our meta-analysis suggests that IKZF1 deletion is a poor prognostic factor for adults with B cell ALL and may be more valuable in BCR-ABL1-negative B cell ALL patients.

Akhter A, Mughal MK, Elyamany G, et al.
Multiplexed automated digital quantification of fusion transcripts: comparative study with fluorescent in-situ hybridization (FISH) technique in acute leukemia patients.
Diagn Pathol. 2016; 11(1):89 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: The World Health Organization (WHO) classification system defines recurrent chromosomal translocations as the sole diagnostic and prognostic criteria for acute leukemia (AL). These fusion transcripts are pivotal in the pathogenesis of AL. Clinical laboratories universally employ conventional karyotype/FISH to detect these chromosomal translocations, which is complex, labour intensive and lacks multiplexing capacity. Hence, it is imperative to explore and evaluate some newer automated, cost-efficient multiplexed technologies to accommodate the expanding genetic landscape in AL.
METHODS: "nCounter® Leukemia fusion gene expression assay" by NanoString was employed to detect various fusion transcripts in a large set samples (n = 94) utilizing RNA from formalin fixed paraffin embedded (FFPE) diagnostic bone marrow biopsy specimens. This series included AL patients with various recurrent translocations (n = 49), normal karyotype (n = 19), or complex karyotype (n = 21), as well as normal bone marrow samples (n = 5). Fusion gene expression data were compared with results obtained by conventional karyotype and FISH technology to determine sensitivity/specificity, as well as positive /negative predictive values.
RESULTS: Junction probes for PML/RARA; RUNX1-RUNX1T1; BCR/ABL1 showed 100 % sensitivity/specificity. A high degree of correlation was noted for MLL/AF4 (85 sensitivity/100 specificity) and TCF3-PBX1 (75 % sensitivity/100 % specificity) probes. CBFB-MYH11 fusion probes showed moderate sensitivity (57 %) but high specificity (100 %). ETV6/RUNX1 displayed discordance between fusion transcript assay and FISH results as well as rare non-specific binding in AL samples with normal or complex cytogenetics.
CONCLUSIONS: Our study presents preliminary data with high correlation between fusion transcript detection by a throughput automated multiplexed platform, compared to conventional karyotype/FISH technique for detection of chromosomal translocations in AL patients. Our preliminary observations, mandates further vast validation studies to explore automated molecular platforms in diagnostic pathology.

Organista-Nava J, Gómez-Gómez Y, Illades-Aguiar B, Leyva-Vázquez MA
Regulation of the miRNA expression by TEL/AML1, BCR/ABL, MLL/AF4 and TCF3/PBX1 oncoproteins in acute lymphoblastic leukemia (Review).
Oncol Rep. 2016; 36(3):1226-32 [PubMed] Related Publications
MicroRNAs (miRNAs) are a class of small endogenous non-coding RNAs that play important regulatory roles by targeting mRNAs for cleavage or translational repression. miRNAs act in diverse biological processes including development, cell growth, apoptosis, and hematopoiesis. The miRNA expression is associated with specific cytogenetic changes and can also be used to discriminate between the different subtypes of leukemia in acute lymphoblastic leukemia with common translocations, it is shown that the miRNAs have the potential to be used for clinical diagnosis and prognosis. We reviewed the roles of miRNA here with emphasis on their function in human leukemia and the mechanisms of the TEL/AML1, BCR/ABL, MLL/AF4 and TCF3/PBX1 oncoproteins on miRNAs expression in acute lymphoblastic leukemia.

Chiaretti S, Gianfelici V, O'Brien SM, Mullighan CG
Advances in the Genetics and Therapy of Acute Lymphoblastic Leukemia.
Am Soc Clin Oncol Educ Book. 2016; 35:e314-22 [PubMed] Related Publications
Acute lymphoblastic leukemia (ALL) remains an important cause of morbidity in children and adults. In this article, we highlight advances in the genetics and therapy of three key subtypes of ALL: T-cell ALL, BCR-ABL1 (Philadelphia [Ph] chromosone-positive), and Ph-like ALL. T-ALL is an aggressive disease that accounts for about 15% and 25% of ALL among pediatric and adult cohorts, respectively, and exhibits a multistep nature of cancer initiation and progression. The integration of cytogenetics, molecular biology, and immunophenotype analyses has led to the identification of defined T-ALL subgroups, such as early T-cell precursor ALL and novel lesions with a prognostic role, for which specific inhibitors are being developed. Ph-positive ALL was historically regarded as a subtype of ALL with a poor prognosis, and allogeneic stem cell transplant was recommended for all patients who could undergo this procedure. The deep complete responses seen with combination tyrosine kinase inhibitors (TKIs) and chemotherapy in Ph-positive ALL, and the reports of long-term survival among some patients not undergoing allogeneic stem cell transplant, has raised the question of whether there is a subset of patients who could be cured without this intervention. Ph-like ALL is a subtype of B-progenitor ALL common among older children and adults and associated with a diverse range of genetic alterations that activate kinase signaling. Ph-like ALL is also associated with poor outcome, for which precision medicine trials identifying kinase alterations and testing TKI therapy are being developed.

Kang ZJ, Liu YF, Xu LZ, et al.
The Philadelphia chromosome in leukemogenesis.
Chin J Cancer. 2016; 35:48 [PubMed] Free Access to Full Article Related Publications
The truncated chromosome 22 that results from the reciprocal translocation t(9;22)(q34;q11) is known as the Philadelphia chromosome (Ph) and is a hallmark of chronic myeloid leukemia (CML). In leukemia cells, Ph not only impairs the physiological signaling pathways but also disrupts genomic stability. This aberrant fusion gene encodes the breakpoint cluster region-proto-oncogene tyrosine-protein kinase (BCR-ABL1) oncogenic protein with persistently enhanced tyrosine kinase activity. The kinase activity is responsible for maintaining proliferation, inhibiting differentiation, and conferring resistance to cell death. During the progression of CML from the chronic phase to the accelerated phase and then to the blast phase, the expression patterns of different BCR-ABL1 transcripts vary. Each BCR-ABL1 transcript is present in a distinct leukemia phenotype, which predicts both response to therapy and clinical outcome. Besides CML, the Ph is found in acute lymphoblastic leukemia, acute myeloid leukemia, and mixed-phenotype acute leukemia. Here, we provide an overview of the clinical presentation and cellular biology of different phenotypes of Ph-positive leukemia and highlight key findings regarding leukemogenesis.

Xu N, Li YL, Li X, et al.
Correlation between deletion of the CDKN2 gene and tyrosine kinase inhibitor resistance in adult Philadelphia chromosome-positive acute lymphoblastic leukemia.
J Hematol Oncol. 2016; 9:40 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Frequency relapses are common in Philadelphia chromosome-positive (Ph-positive) acute lymphoblastic leukemia (ALL) following tyrosine kinase inhibitors (TKIs). CDKN2A/B is believed to contribute to this chemotherapy resistance.
METHODS: To further investigate the association between CDKN2 status and TKI resistance, the prevalence of CDKN2 deletions and its correlation with a variety of clinical features was assessed in 135 Ph-positive ALL patients using interphase fluorescence in situ hybridization (I-FISH).
RESULTS: Results showed that no difference occurred between patients with CDKN2 deletion (44/135) and wild-type patients in sex, age, and complete remission (CR) rate following induction chemotherapy combined with tyrosine kinase inhibitors (TKIs). However, CDKN2 deletion carriers demonstrated higher white blood cell (WBC) count, enhanced rates of hepatosplenomegaly (P = 0.006), and upregulation of CD20 expression (P = 0.001). Moreover, deletions of CDKN2 resulted in lower rates of complete molecular response (undetectable BCR/ABL), increased cumulative incidence of relapse, short overall survival (OS), and disease-free survival (DFS) time (P < 0.05) even though these patients received chemotherapy plus TKIs followed by allogenic hematopoietic stem cell transplantation (Allo-HSCT). In the case of 44 patients who presented with CDKN2 deletion, 18 patients were treated with dasatinib treatment, and another 26 patients were treated with imatinib therapy, and our study found that there were no differences associated with OS (P = 0.508) and DFS (P = 0.555) between the two groups.
CONCLUSIONS: CDKN2 deletion is frequently acquired during Ph-positive ALL progression and serves as a poor prognostic marker of long-term outcome in Ph-positive ALL patients with CDKN2 deletion even after the second-generation tyrosine kinase inhibitor treatment.

Limsuwanachot N, Siriboonpiputtana T, Karntisawiwat K, et al.
Multiplex RT-PCR Assay for Detection of Common Fusion Transcripts in Acute Lymphoblastic Leukemia and Chronic Myeloid Leukemia Cases.
Asian Pac J Cancer Prev. 2016; 17(2):677-84 [PubMed] Related Publications
BACKGROUND: Acute lymphoblastic leukemia (ALL) is a heterogeneous disease which requires a risk-stratified approach for appropriate treatment. Specific chromosomal translocations within leukemic blasts are important prognostic factors that allow identification of relevant subgroups. In this study, we developed a multiplex RT-PCR assay for detection of the 4 most frequent translocations in ALL (BCR-ABL, TEL-AML1, MLL-AF4, and E2A- PBX1).
MATERIALS AND METHODS: A total of 214 diagnosed ALL samples from both adult and pediatric ALL and 14 cases of CML patients (154 bone marrow and 74 peripheral blood samples) were assessed for specific chromosomal translocations by cytogenetic and multiplex RT-PCR assays.
RESULTS: The results showed that 46 cases of ALL and CML (20.2%) contained the fusion transcripts. Within the positive ALL patients, the most prevalent cryptic translocation observed was mBCR-ABL (p190) at 8.41%. In addition, other genetic rearrangements detected by the multiplex PCR were 4.21% TEL-AML1 and 2.34% E2A-PBX1, whereas MLL-AF4 exhibited negative results in all tested samples. Moreover, MBCR-ABL was detected in all 14 CML samples. In 16 samples of normal karyotype ALL (n=9), ALL with no cytogentic result (n=4) and CML with no Philadelphia chromosome (n=3), fusion transcripts were detected.
CONCLUSIONS: Multiplex RT-PCR provides a rapid, simple and highly sensitive method to detect fusion transcripts for prognostic and risk stratification of ALL and CML patients.

Kurita D, Hatta Y, Hojo A, et al.
Adult acute lymphoblastic leukemia with a rare b3a3 type BCR/ABL1 fusion transcript.
Cancer Genet. 2016; 209(4):161-5 [PubMed] Related Publications
The Philadelphia chromosome (Ph) is the most frequent chromosomal abnormality detected in adult acute lymphoblastic leukemia (ALL). This chromosome forms the BCR/ABL1 fusion gene; thus, ABL1 exon a2 is generally used as a primer-binding region for the detection of the fusion transcript via reverse transcription polymerase chain reaction (RT-PCR). We observed a rare case of adult Ph-positive (Ph(+)) ALL, in which the BCR/ABL1 fusion transcript was not detected using the ABL1 exon a2 region primer. However, we were able to isolate a PCR product by RT-PCR with the BCR exon 13 (b2) and ABL1 exon a3 primers. Analysis of the sequence of the RT-PCR product revealed that the fusion point was between BCR exon 14 (b3) and ABL1 exon a3, and that the transcript lacked ABL1 exon a2. The patient achieved cytogenetic remission through combination chemotherapies, but relapse occurred before hematopoietic stem cell transplantation and the patient died 11 months after the initialization of chemotherapies. If the BCR/ABL1 fusion transcript is undetected with the ABL1 exon a2 region primer in Ph(+) ALL cases, an RT-PCR analysis that can detect the b3a3 type BCR/ABL1 fusion transcript should be considered to improve diagnosis.

Naren D, Wu J, Gong Y, et al.
Niemann-Pick disease type C1(NPC1) is involved in resistance against imatinib in the imatinib-resistant Ph+ acute lymphoblastic leukemia cell line SUP-B15/RI.
Leuk Res. 2016; 42:59-67 [PubMed] Related Publications
Niemann-Pick disease type C1 (NPC1) is involved in cholesterol trafficking and may normally function as a transmembrane efflux pump. Previous studies showed that its dysfunction can lead to cholesterol and daunorubicin accumulation in the cytoplasmic endosomal/lysosomal system, lead to Niemann-Pick disease and resistance to anticancer drugs. In the present study, NPC1 was shown by microarray analysis to be more highly expressed in the Ph+ acute lymphoblastic leukemia cell line SUP-B15/RI, an imatinib-resistant variant of SUP-B15/S cells without bcr-abl gene mutation established in our lab. Further investigation revealed a defect in the functional capacity of the NPC1 protein demonstrated by filipin staining accompanied by a lower intracellular imatinib mesylate(IM) concentration by high-performance liquid chromatography in SUP-B15/RI compared with SUP-B15/S cells. Furthermore, U18666A, an inhibitor of NPC1 function, was used to block cholesterol trafficking to imitate the NPC1 defect in SUP-B15/S cells, leading to higher NPC1 expression, stronger filipin fluorescence, lower intracellular IM concentrations and greater resistance against IM. Samples from non-mutated relapsed Ph+ ALL patients also showed higher NPC1 expression compared with IM-sensitive patients. Our experiment may reveal a new mechanism of IM resistance in Ph+ ALL.

Gupta SK, Bakhshi S, Kumar L, et al.
IKZF1 (IKAROS) deletions in B-ALL and its clinical correlation: A prospective study from a tertiary care centre in Northern India.
Leuk Res. 2016; 41:7-11 [PubMed] Related Publications
INTRODUCTION: IKZF1 deletions have been reported with variable frequency in B-ALL. This study was carried out to find the prevalence and profile of IKZF1 deletions and their correlation in B-ALL.
METHODS: The untreated B-ALL cases were prospectively analyzed for IKZF1 deletions over a period of eleven months using multiplex ligation dependent probe amplification (MLPA). The IKZF1 deletions were classified into three functional groups-dominant negative, haploinsufficiency and others. The response to induction chemotherapy was correlated with the IKZF1 deletion status.
RESULTS: The median age of 101 cases was 7 years (1-67) with 82 pediatric (<18 years) cases. Fifteen cases were positive for BCR-ABL. The IKZF1 deletions were detected in 29 (28.7%) cases; 53% BCR-ABL positive, 24% BCR-ABL negative, 47% adult and 24% pediatric cases. Out of the 29 deletions, 19 (66%) were haploinsufficiency, 8 (28%) were dominant negative and 2 others. The IKZF1 deleted cases had higher induction failure rates compared to the cases without IKZF1 deletions.
CONCLUSIONS: The IKZF1 deletions were detected in 28.7% B-ALL patients. These were more common in BCR-ABL positive and adult B-ALL compared to the BCR-ABL negative and pediatric cases, respectively. The haploinsufficiency was commoner than dominant negative IKZF1 deletions. IKZF1 deletions correlated with higher induction failure.

Ishibashi T, Yaguchi A, Terada K, et al.
Ph-like ALL-related novel fusion kinase ATF7IP-PDGFRB exhibits high sensitivity to tyrosine kinase inhibitors in murine cells.
Exp Hematol. 2016; 44(3):177-88.e5 [PubMed] Related Publications
ATF7IP-PDGFRB is a novel PDGFRB-related fusion gene identified in B-cell precursor acute lymphoblastic leukemia (BCP-ALL) with a signature similar to that of Ph1 ALL, so-called Ph-like ALL. When we introduced ATF7IP-PDGFRB, murine Ba/F3 cells acquired the ability to proliferate in an interleukin (IL)-3-independent manner. On the contrary, the expression of wild-type PDGFRB is not sufficient to acquire the ability for IL-3-independent proliferation in Ba/F3 cells. The introduction of ATF7IP-PDGFRB also induces a typical gene expression profile for Ph1-ALL in Ba/F3 cells. A series of biochemical and cell biological experiments revealed the constitutive activation of ATF7IP-PDGFRB as well as downstream signaling molecules, including AKT and MAPK. Although the phosphoinositide 3-kinase inhibitor led to cell death in both cells into which ATF7IP-PDGFRB had been introduced and IL-3-maintained Mock cells, MEK inhibitor selectively led to cell death into which ATF7IP-PDGFRB had been introduced. The introduction of tyrosine to phenylalanine mutations at binding sites of adaptor molecules important in the MAPK pathway located in the PDGFRB portion abolished ATF7IP-PDGFRB-mediated cell transformation, suggesting that MAPK-mediated signals are critical in ATF7IP-PDGFRB-mediated cell transformation. On treatment with tyrosine kinase inhibitors, ATF7IP-PDGFRB-expressing, but not Mock, Ba/F3 cells underwent rapid apoptosis accompanied by reduced phosphorylation of MAPK. Importantly, the sensitivity of ATF7IP-PDGFRB-expressing Ba/F3 cells to imatinib is significantly higher than that of BCR-ABL1-transformed Ba/F3 cells, as assessed by the IC50. Taken together, ATF7IP-PDGFRB has transforming potential via the constitutive activation of MAPK and participates in the pathogenesis of Ph-like ALL. Our observations suggest the therapeutic importance of tyrosine kinase inhibitors and possibly MEK inhibitor for a subset of BCP-ALL harboring PDGFRB-related fusion kinases.

Shingleton JR, Hemann MT
The Chromatin Regulator CHD8 Is a Context-Dependent Mediator of Cell Survival in Murine Hematopoietic Malignancies.
PLoS One. 2015; 10(11):e0143275 [PubMed] Free Access to Full Article Related Publications
Aberrant chromatin regulation is a frequent driver of leukemogenesis. Mutations in chromatin regulators often result in more stem-like cells that seed a bulk leukemic population. Inhibitors targeting these proteins represent an emerging class of therapeutics, and identifying further chromatin regulators that promote disease progression may result in additional drug targets. We identified the chromatin-modifying protein CHD8 as necessary for cell survival in a mouse model of BCR-Abl+ B-cell acute lymphoblastic leukemia. This disease has a poor prognosis despite treatment with kinase inhibitors targeting BCR-Abl. Although implicated as a risk factor in autism spectrum disorder and a tumor suppressor in prostate and lung cancer, the mechanism of CHD8's activity is still unclear and has never been studied in the context of hematopoietic malignancies. Here we demonstrate that depletion of CHD8 in B-ALL cells leads to cell death. While multiple B cell malignancies were dependent on CHD8 expression for survival, T cell malignancies displayed milder phenotypes upon CHD8 knockdown. In addition, ectopic expression of the Notch1 intracellular domain in a T cell malignancy partially alleviated the detrimental effect of CHD8 depletion. Our results demonstrate that CHD8 has a context-dependent role in cell survival, and its inhibition may be an effective treatment for B lymphoid malignancies.

Goud TM, Al Salmani KK, Al Harasi SM, et al.
Importance of FISH combined with Morphology, Immunophenotype and Cytogenetic Analysis of Childhood/ Adult Acute Lymphoblastic Leukemia in Omani Patients.
Asian Pac J Cancer Prev. 2015; 16(16):7343-50 [PubMed] Related Publications
Genetic changes associated with acute lymphoblastic leukemia (ALL) provide very important diagnostic and prognostic information with a direct impact on patient management. Detection of chromosome abnormalities by conventional cytogenetics combined with fluorescence in situ hybridization (FISH) play a very significant role in assessing risk stratification. Identification of specific chromosome abnormalities has led to the recognition of genetic subgroups based on reciprocal translocations, deletions and modal number in B or T-cell ALL. In the last twelve years 102 newly diagnosed childhood/adult ALL bone marrow samples were analysed for chromosomal abnormalities with conventional G-banding, and FISH (selected cases) using specific probes in our hospital. G-banded karyotype analysis found clonal numerical and/or structural chromosomal aberrations in 74.2% of cases. Patients with pseudodiploidy represented the most frequent group (38.7%) followed by high hyperdiploidy group (12.9%), low hyperdiploidy group (9.7%), hypodiploidy (<46) group (9.7%) and high hypertriploidy group (3.2%). The highest observed numerical chromosomal alteration was high hyperdiploidy (12.9%) with abnormal karyotypes while abnormal 12p (7.5%) was the highest observed structural abnormality followed by t(12;21)(p13.3;q22) resulting in ETV6/RUNX1 fusion (5.4%) and t(9;22)(q34.1;q11.2) resulting in BCR/ABL1 fusion (4.3%). Interestingly, we identified 16 cases with rare and complex structural aberrations. Application of the FISH technique produced major improvements in the sensitivity and accuracy of cytogenetic analysis with ALL patients. In conclusion it confirmed heterogeneity of ALL by identifying various recurrent chromosomal aberrations along with non-specific rearrangements and their association with specific immunophenotypes. This study pool is representative of paediatric/adult ALL patients in Oman.

Mühlbacher V, Haferlach T, Kern W, et al.
Array-based comparative genomic hybridization detects copy number variations with prognostic relevance in 80% of ALL with normal karyotype or failed chromosome analysis.
Leukemia. 2016; 30(2):318-24 [PubMed] Related Publications
Pretreatment cytogenetics is an important parameter for risk stratification and therapy approach in acute lymphoblastic leukemia (ALL). However, in up to 30% of cases, chromosome banding analysis (CBA) fails or reveals a normal karyotype. To characterize the subset of ALL with normal karyotype or failed CBA, we performed fluorescence in situ hybridization (FISH) or PCR for BCR-ABL1 and MLL rearrangements as well as array comparative genomic hybridization (aCGH) in 186 adult patients. We further carried out FISH for MYC in cases with Burkitt leukemia phenotype. FISH or PCR revealed one of the respective rearrangements in 22% of patients. In 80% of cases, copy number variations (CNV) were identified by aCGH. In 22% of cases, all CNV were below the resolution of CBA. On the basis of results of FISH, RT-PCR and aCGH, patients were categorized into three groups. The novel subset of patients with submicroscopic CNV only showed an overall survival at 3 years of 84% compared with 64% for patients classified as adverse abnormalities and 77% for cases with other aberrations (P=0.046). Thus, ALL with non-informative CBA can be further classified by FISH and aCGH providing prognostic information, which may be useful for a more individualized therapy.

Churchman ML, Low J, Qu C, et al.
Efficacy of Retinoids in IKZF1-Mutated BCR-ABL1 Acute Lymphoblastic Leukemia.
Cancer Cell. 2015; 28(3):343-56 [PubMed] Free Access to Full Article Related Publications
Alterations of IKZF1, encoding the lymphoid transcription factor IKAROS, are a hallmark of high-risk acute lymphoblastic leukemia (ALL), however the role of IKZF1 alterations in ALL pathogenesis is poorly understood. Here, we show that in mouse models of BCR-ABL1 leukemia, Ikzf1 and Arf alterations synergistically promote the development of an aggressive lymphoid leukemia. Ikzf1 alterations result in acquisition of stem cell-like features, including self-renewal and increased bone marrow stromal adhesion. Retinoid receptor agonists reversed this phenotype, partly by inducing expression of IKZF1, resulting in abrogation of adhesion and self-renewal, cell cycle arrest, and attenuation of proliferation without direct cytotoxicity. Retinoids potentiated the activity of dasatinib in mouse and human BCR-ABL1 ALL, providing an additional therapeutic option in IKZF1-mutated ALL.

Shi F, Len Y, Gong Y, et al.
Ribavirin Inhibits the Activity of mTOR/eIF4E, ERK/Mnk1/eIF4E Signaling Pathway and Synergizes with Tyrosine Kinase Inhibitor Imatinib to Impair Bcr-Abl Mediated Proliferation and Apoptosis in Ph+ Leukemia.
PLoS One. 2015; 10(8):e0136746 [PubMed] Free Access to Full Article Related Publications
The eukaryotic translation initiation factor 4E (eIF4E), which is the main composition factor of eIF4F translation initiation complex, influences the growth of tumor through modulating cap-dependent protein translation. Previous studies reported that ribavirin could suppress eIF4E-controlled translation and reduce the synthesis of onco-proteins. Here, we investigated the anti-leukemic effects of ribavirin alone or in combination with tyrosine kinase inhibitor imatinib in Philadelphia chromosome positive (Ph+) leukemia cell lines SUP-B15 (Ph+ acute lymphoblastic leukemia cell line, Ph+ ALL) and K562 (chronic myelogenous leukemia cell line, CML). Our results showed that ribavirin had anti-proliferation effect; it down-regulated the phosphorylation levels of Akt, mTOR, 4EBP1, and eIF4E proteins in the mTOR/eIF4E signaling pathway, and MEK, ERK, Mnk1 and eIF4E proteins in ERK/Mnk1/eIF4E signaling pathway; reduced the expression of Mcl-1 (a translation substrates of eIF4F translation initiation complex) at protein synthesis level not mRNA transcriptional level; and induced cell apoptosis in both SUP-B15 and K562. 7-Methyl-guanosine cap affinity assay further demonstrated that ribavirin remarkably increased the eIF4E binding to 4EBP1 and decreased the combination of eIF4E with eIF4G, consequently resulting in a major inhibition of eIF4F complex assembly. The combination of ribavirin with imatinib enhanced antileukemic effects mentioned above, indicating that two drugs have synergistic anti-leukemic effect. Consistent with the cell lines, similar results were observed in Ph+ acute lymphoblastic primary leukemic blasts; however, the anti-proliferative role of ribavirin in other types of acute primary leukemic blasts was not obvious, which indicated that the anti-leukemic effect of ribavirin was different in cell lineages.

Iqbal Z, Akhtar T, Awan T, et al.
High frequency and poor prognosis of late childhood BCR-ABL-positive and MLL-AF4-positive ALL define the need for advanced molecular diagnostics and improved therapeutic strategies in pediatric B-ALL in Pakistan.
Mol Diagn Ther. 2015; 19(5):277-87 [PubMed] Related Publications
BACKGROUND: Fusion oncogenes (FOs) resulting from chromosomal abnormalities have an important role in leukemogenesis in pediatric B cell acute lymphoblastic leukemia (ALL). The most common FOs are BCR-ABL, MLL-AF4, ETV6-RUNX1, and TCF3-PBX1, all of which have important prognostic and drug selection implications. Moreover, frequencies of FOs have ethnic variations. We studied Pakistani frequencies of FOs, clinical pattern, and outcome in pediatric B-ALL.
METHODS: FOs were studied in 188 patients at diagnosis using reverse transcriptase-polymerase chain reaction (RT-PCR) and interphase fluorescent in situ hybridization (FISH). Data were analyzed using SPSS version 17 (SPSS Inc., Chicago, IL, USA).
RESULTS: FOs were detected in 87.2 % of patients. Mean overall survival was 70.9 weeks, 3-year survival was 31.9 %, and 3-year relapse-free survival was 18.1 %. Four patients died of drug toxicities. ETV6-RUNX1 (19.14 %) had better survival (110.9 weeks; p = 0.03); TCF3-PBX1 (2.1 %) was associated with inferior outcome and higher central nervous system (CNS) relapse risk; MLL-AF4 (18.1 %) was more common in the 8- to 15-year age group (24/34; p = 0.001) and was associated with organomegaly, low platelet count, and poor survival; and BCR-ABL (47.9 %) was associated with older age (7-15 years, 52/90), lower remission rates, shorter survival (43.73 ± 4.24 weeks) and higher white blood cell count. Overall, MLL-AF4 and BCR-ABL were detected in 66 % of B-ALL, presented in later childhood, and were associated with poor prognosis and inferior survival.
CONCLUSIONS: This study reports the highest ethnic frequency of BCR-ABL FO in pediatric ALL, and is consistent with previous reports from our region. Poor prognosis BCR-ABL and MLL-AF4 was detected in two-thirds of pediatric B-ALL and is likely to be the reason for the already reported poor survival of childhood ALL in South-East Asia. Furthermore, MLL-AF4, usually most common in infants, presented in later childhood in most of the ALL patients, which was one of the unique findings in our study. The results presented here highlight the need for mandatory inclusion of molecular testing for pediatric ALL patients in clinical decision making, together with the incorporation of tyrosine kinase inhibitors, as well as hematopoietic stem cell transplantation facilities, to improve treatment outcome for patients in developing countries.

Chopra A, Soni S, Verma D, et al.
Prevalence of common fusion transcripts in acute lymphoblastic leukemia: A report of 304 cases.
Asia Pac J Clin Oncol. 2015; 11(4):293-8 [PubMed] Related Publications
AIM: Information about fusion transcripts in acute lymphoblastic leukemia (ALL) is used to risk-stratify patients, decide on the treatment and to detect minimal residual disease. This study was conducted to determine the frequency of common fusion transcripts BCR-ABL, TEL-AML1, MLL-AF4 and E2A-PBX1 for B-ALL and SIL-TAL1 for T-ALL as seen at a tertiary care center in India.
METHODS: Up to 304 new cases of ALL (271 B-ALL and 33 T-ALL) diagnosed on morphology, cytochemistry and immunophenotyping were studied. All were screened for the common fusion transcripts by RT-PCR.
RESULTS: Both our B- (218/271; 80.4%) and T-ALL (26/33; 78.8%) patients were largely children. In the B-ALL children, BCR-ABL was detected in 26/218 (11.9%), E2A-PBX1 in 13/218 (5.9%), TEL-AML1 in 16/218 (7.3%) and MLL-AF4 in 3/218 (1.4%) patients. Adult B-ALL cases had BCR-ABL in 15/53 (28.3%) and E2A-PBX in 2/53 (3.8%); however, no other fusion transcript was detected. SIL-TAL1 was found in four of 26 pediatric (15%) and zero of 7 adult T-ALL cases.
CONCLUSION: The higher incidence of BCR-ABL and lower incidence of TEL-AML1 in our ALL patients, both in children and adults as compared with the West, suggests that patients in India may be biologically different. This difference may explain at least in part the higher relapse rate and poorer outcome in our B-ALL cases.

Zhang R, Yang JY, Sun HQ, et al.
Comparison of minimal residual disease (MRD) monitoring by WT1 quantification between childhood acute myeloid leukemia and acute lymphoblastic leukemia.
Eur Rev Med Pharmacol Sci. 2015; 19(14):2679-88 [PubMed] Related Publications
OBJECTIVE: Wilms tumor gene 1 (WT1) has been identified as an independent risk prognostic factor in acute leukemia. However, there exists a controversy that WT1 as a marker for minimal residual disease (MRD) monitoring in acute leukemias. We detected WT1-RNA transcript level to estimate the diagnostic value of monitoring MRD in childhood acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL).
PATIENTS AND METHODS: WT1 mRNA expression levels were detected by real-time quantitative reverse transcriptase PCR (qRT-PCR) in bone marrow (BM) samples from 107 childhood ALL and 35 childhood AML at diagnosis. MRD was consecutively performed after induction and consolidation (early intensification in ALL) chemotherapy. Receiver operating characteristics (ROC) analysis and the largest areas under the curve (AUC) were applied to define optimal threshold value of MRD level. Sensitivity, specificity, positive likelihood ratio (+LR) and negative likelihood ratio (-LR) were used to evaluate diagnostic power for MRD. Relapse free survival (RFS) was evaluated by the Kaplan-Meier statistical method.
RESULTS: The largest areas under the curve (AUC), specificity, +LR and -LR showed higher accuracy in childhood AML than ALL. Compared the diagnostic parameters, the post-induction time wasn't good enough to show the better time than post-consolidation time for MRD assessment in AML. The threshold was set at 150 WT1 copies/104 ABL copies as the optimal cut-off value of MRD level post induction in childhood AML. MRD+ (WT1>150) children had increased the risk of relapse with poor prognosis, showing lower RFS than MRD- group (p=0.01). However, the threshold 70 WT1 copies/104 ABL copies post induction in childhood ALL did not show clinical significance for predicting prognosis (p=0.056).
CONCLUSIONS: WT1 gene will be a useful marker for monitoring MRD to predict relapse in childhood AML. But it did not show good enough to monitor MRD in childhood ALL.

Zhou J, Papenhausen P, Shao H
Therapy-related acute myeloid leukemia with eosinophilia, basophilia, t(4;14)(q12;q24) and PDGFRA rearrangement: a case report and review of the literature.
Int J Clin Exp Pathol. 2015; 8(5):5812-20 [PubMed] Free Access to Full Article Related Publications
The myeloid and lymphoid neoplasms with eosinophilia and PDGFRA gene rearrangements usually show a good response to Imatinib and are typically associated with a normal karyotype, occasionally exhibiting a secondary chromosomal abnormality associated with clonal evolution. Five variant translocations involving PDGFRA have been reported. Here, we report a rare case of therapy-related acute myeloid leukemia with PDGFRA rearrangement after chemotherapy for prior B lymphoblastic leukemia (B-ALL). The patient had a history of BCR-ABL negative, hypodiploid B-ALL in complete remission after chemotherapy. However, 15 months later the patient developed acute myeloid leukemia with rapidly increasing eosinophilia, basophilia and a complex karyotype that included a novel t(4;14)(q12;q24). FIP1L1 was not associated with the PDGFRA rearrangement. The patient had a very aggressive clinical course, and died from the disease shortly after diagnosis. This is the first case of a primary therapy-related myeloid neoplasm with secondary PDGFRA rearrangement. The t(4:14)(q12;q24) is joining the growing list of the variant translocations involving PDGFRA.

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