Gene Summary

Gene:PBX1; pre-B-cell leukemia homeobox 1
Summary:This gene encodes a nuclear protein that belongs to the PBX homeobox family of transcriptional factors. Studies in mice suggest that this gene may be involved in the regulation of osteogenesis, and required for skeletal patterning and programming. A chromosomal translocation, t(1;19) involving this gene and TCF3/E2A gene, is associated with pre-B-cell acute lymphoblastic leukemia. The resulting fusion protein, in which the DNA binding domain of E2A is replaced by the DNA binding domain of this protein, transforms cells by constitutively activating transcription of genes regulated by the PBX protein family. Alternatively spliced transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Mar 2011]
Databases:OMIM, VEGA, HGNC, Ensembl, GeneCard, Gene
Protein:pre-B-cell leukemia transcription factor 1
Source:NCBIAccessed: 06 August, 2015


What does this gene/protein do?
Show (28)

Cancer Overview

Research Indicators

Publications Per Year (1990-2015)
Graph generated 06 August 2015 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.

  • Repressor Proteins
  • Pathology, Molecular
  • TCF3
  • Oligonucleotide Array Sequence Analysis
  • Stochastic Processes
  • Gene Expression Profiling
  • Wilms Tumour
  • Precursor B-Cell Lymphoblastic Leukemia-Lymphoma
  • Polymerase Chain Reaction
  • Translocation
  • Karyotyping
  • Messenger RNA
  • Oncogene Fusion Proteins
  • Acute Lymphocytic Leukaemia
  • Chromosome 19
  • Homologous Transplantat
  • Neoplasm Proteins
  • Chromosome Aberrations
  • Cancer Gene Expression Regulation
  • DNA-Binding Proteins
  • Cervical Cancer
  • Fusion Proteins, bcr-abl
  • Immunophenotyping
  • Core Binding Factor Alpha 2 Subunit
  • Chromosome 1
  • KMT2A
  • Childhood Cancer
  • Infant
  • Cancer RNA
  • Tumor Markers
  • Gene Rearrangement
  • Prenatal Exposure Delayed Effects
  • pbx1
  • Transcription
  • Molecular Sequence Data
  • Homeodomain Proteins
  • Burkitt Lymphoma
  • Base Sequence
  • FISH
  • Adolescents
Tag cloud generated 06 August, 2015 using data from PubMed, MeSH and CancerIndex

Specific Cancers (5)

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

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

Latest Publications: PBX1 (cancer-related)

Deucher AM, Qi Z, Yu J, et al.
BCL6 expression correlates with the t(1;19) translocation in B-lymphoblastic leukemia.
Am J Clin Pathol. 2015; 143(4):547-57 [PubMed] Related Publications
OBJECTIVES: Study to date suggests that BCL6 protein expression in B-cell neoplasia predominates in germinal center-derived tumors, but less is known regarding its expression in B-lymphoblastic leukemia. Therefore, we designed a comprehensive study of BCL6 expression in B-lymphoblastic leukemia.
METHODS: BCL6, LMO, and HGAL protein expression in B-lymphoblastic leukemia was investigated using immunohistochemical staining of paraffin-embedded bone marrow specimens. Cryptic TCF3(E2A)-PBX1 rearrangements were investigated using interphase fluorescence in situ hybridization.
RESULTS: Six (12%) of 52 B-lymphoblastic leukemias demonstrated BCL6 protein expression, with B-cell lymphoblastic leukemias containing a t(1;19) translocation demonstrating the strongest staining (three of three). Additional t(1;19) cases beyond the screening study showed similar results. Public microarray expression database mining showed that BCL6 messenger RNA expression levels in B-lymphoblastic leukemia correlated with the protein expression findings. Finally, other markers of B-cell development correlated with BCL6 expression in t(1;19) B-lymphoblastic leukemia cases, with LMO2 and HGAL proteins expressed in six (67%) of nine and eight (89%) of nine cases, respectively.
CONCLUSIONS: BCL6 expression is present in a subset of B-lymphoblastic leukemias, especially in cases containing the 1;19 translocation. Investigation for TCF3(E2A)-PBX1 rearrangements may be useful in BCL6-positive B-lymphoblastic leukemia.

Geng H, Hurtz C, Lenz KB, et al.
Self-enforcing feedback activation between BCL6 and pre-B cell receptor signaling defines a distinct subtype of acute lymphoblastic leukemia.
Cancer Cell. 2015; 27(3):409-25 [PubMed] Related Publications
Studying 830 pre-B ALL cases from four clinical trials, we found that human ALL can be divided into two fundamentally distinct subtypes based on pre-BCR function. While absent in the majority of ALL cases, tonic pre-BCR signaling was found in 112 cases (13.5%). In these cases, tonic pre-BCR signaling induced activation of BCL6, which in turn increased pre-BCR signaling output at the transcriptional level. Interestingly, inhibition of pre-BCR-related tyrosine kinases reduced constitutive BCL6 expression and selectively killed patient-derived pre-BCR(+) ALL cells. These findings identify a genetically and phenotypically distinct subset of human ALL that critically depends on tonic pre-BCR signaling. In vivo treatment studies suggested that pre-BCR tyrosine kinase inhibitors are useful for the treatment of patients with pre-BCR(+) ALL.

Hajingabo LJ, Daakour S, Martin M, et al.
Predicting interactome network perturbations in human cancer: application to gene fusions in acute lymphoblastic leukemia.
Mol Biol Cell. 2014; 25(24):3973-85 [PubMed] Free Access to Full Article Related Publications
Genomic variations such as point mutations and gene fusions are directly or indirectly associated with human diseases. They are recognized as diagnostic, prognostic markers and therapeutic targets. However, predicting the functional effect of these genetic alterations beyond affected genes and their products is challenging because diseased phenotypes are likely dependent of complex molecular interaction networks. Using as models three different chromosomal translocations-ETV6-RUNX1 (TEL-AML1), BCR-ABL1, and TCF3-PBX1 (E2A-PBX1)-frequently found in precursor-B-cell acute lymphoblastic leukemia (preB-ALL), we develop an approach to extract perturbed molecular interactions from gene expression changes. We show that the MYC and JunD transcriptional circuits are specifically deregulated after ETV6-RUNX1 and TCF3-PBX1 gene fusions, respectively. We also identified the bulk mRNA NXF1-dependent machinery as a direct target for the TCF3-PBX1 fusion protein. Through a novel approach combining gene expression and interactome data analysis, we provide new insight into TCF3-PBX1 and ETV6-RUNX1 acute lymphoblastic leukemia.

Agaram NP, Chen HW, Zhang L, et al.
EWSR1-PBX3: a novel gene fusion in myoepithelial tumors.
Genes Chromosomes Cancer. 2015; 54(2):63-71 [PubMed] Free Access to Full Article Related Publications
The genetics of myoepithelial tumors (ME) of soft tissue and bone have recently been investigated, with EWSR1-related gene fusions being seen in approximately half of the tumors. The fusion partners of EWSR1 so far described include POU5F1, PBX1, ZNF444 and, in a rare case, ATF1. We investigated by RNA sequencing an index case of EWSR1-rearranged ME of the tibia, lacking a known fusion partner, and identified a novel EWSR1-PBX3 fusion. The fusion was further validated by reverse transcriptase polymerase chain reaction and fluorescence in situ hybridization (FISH). To evaluate if this is a recurrent event, an additional cohort of 22 EWSR1-rearranged ME cases lacking a fusion partner were screened by FISH for abnormalities in PBX3 gene. Thus, two additional cases were identified showing an EWSR1-PBX3 gene fusion. One of them was also intraosseous involving the ankle, while the other occurred in the soft tissue of the index finger. The morphology of the EWSR1-PBX3 fusion positive cases showed similar findings, with nests or sheets of epithelioid to spindle cells in a partially myxoid to collagenous matrix. All three cases showed expression of S100 and EMA by immunohistochemistry. In summary, we report a novel EWSR1-PBX3 gene fusion in a small subset of ME, thereby expanding the spectrum of EWSR1-related gene fusions seen in these tumors. This gene fusion seems to occur preferentially in skeletal ME, with two of the three study cases occurring in intraosseous locations.

Risolino M, Mandia N, Iavarone F, et al.
Transcription factor PREP1 induces EMT and metastasis by controlling the TGF-β-SMAD3 pathway in non-small cell lung adenocarcinoma.
Proc Natl Acad Sci U S A. 2014; 111(36):E3775-84 [PubMed] Free Access to Full Article Related Publications
Pre-B-cell leukemia homeobox (Pbx)-regulating protein-1 (Prep1) is a ubiquitous homeoprotein involved in early development, genomic stability, insulin sensitivity, and hematopoiesis. Previously we have shown that Prep1 is a haploinsufficient tumor suppressor that inhibits neoplastic transformation by competing with myeloid ecotropic integration site 1 for binding to the common heterodimeric partner Pbx1. Epithelial-mesenchymal transition (EMT) is controlled by complex networks of proinvasive transcription factors responsive to paracrine factors such as TGF-β. Here we show that, in addition to inhibiting primary tumor growth, PREP1 is a novel EMT inducer and prometastatic transcription factor. In human non-small cell lung cancer (NSCLC) cells, PREP1 overexpression is sufficient to trigger EMT, whereas PREP1 down-regulation inhibits the induction of EMT in response to TGF-β. PREP1 modulates the cellular sensitivity to TGF-β by inducing the small mothers against decapentaplegic homolog 3 (SMAD3) nuclear translocation through mechanisms dependent, at least in part, on PREP1-mediated transactivation of a regulatory element in the SMAD3 first intron. Along with the stabilization and accumulation of PBX1, PREP1 induces the expression of multiple activator protein 1 components including the proinvasive Fos-related antigen 1 (FRA-1) oncoprotein. Both FRA-1 and PBX1 are required for the mesenchymal changes triggered by PREP1 in lung tumor cells. Finally, we show that the PREP1-induced mesenchymal transformation correlates with significantly increased lung colonization by cells overexpressing PREP1. Accordingly, we have detected PREP1 accumulation in a large number of human brain metastases of various solid tumors, including NSCLC. These findings point to a novel role of the PREP1 homeoprotein in the control of the TGF-β pathway, EMT, and metastasis in NSCLC.

Puls F, Arbajian E, Magnusson L, et al.
Myoepithelioma of bone with a novel FUS-POU5F1 fusion gene.
Histopathology. 2014; 65(6):917-22 [PubMed] Related Publications
AIMS: Myoepithelial tumours of soft tissue are rare lesions with a broad morphological and clinical spectrum. Previous studies have found EWSR1 rearrangements in approximately half of all cases and PBX1, ZNF44 and POU5F1 have been identified as recurrent fusion partners. In bone, only a small number of myoepithelial tumours have been described. We investigated an intraosseous myoepithelioma of the sacrum in a 54-year-old man without EWSR1 rearrangement for the presence of other fusion genes.
METHODS AND RESULTS: G-banding analysis, SNP-array and fluorescence in situ hybridisation suggested rearrangement of the FUS and POU5F1 genes. RT-PCR confirmed a chimeric in-frame transcript fusing FUS exon 5 to POU5F1 exon 2. The clinical course after en bloc resection was without recurrence or metastasis over a period of 87 months.
CONCLUSION: We report a novel FUS-POU5F1 fusion gene in an intraosseous myoepithelioma of the sacrum. This case highlights that FUS can replace EWSR1 as the N-terminal transactivator in oncogenic fusion genes in myoepithelial tumours, similar to that which has previously been demonstrated in other tumour entities. Thus, in addition to EWSR1, also FUS needs to be considered as a potential fusion partner in the molecular work up of myoepithelial tumours.

Diakos C, Xiao Y, Zheng S, et al.
Direct and indirect targets of the E2A-PBX1 leukemia-specific fusion protein.
PLoS One. 2014; 9(2):e87602 [PubMed] Free Access to Full Article Related Publications
E2A-PBX1 is expressed as a result of the t(1;19) chromosomal translocation in nearly 5% of cases of childhood acute lymphoblastic leukemia. The E2A-PBX1 chimeric transcription factor contains the N-terminal transactivation domain of E2A (TCF3) fused to the C-terminal DNA-binding homeodomain of PBX1. While there is no doubt of its oncogenic potential, the mechanisms of E2A-PBX1-mediated pre-B cell transformation and the nature of direct E2A-PBX1 target genes and pathways remain largely unknown. Herein we used chromatin immunoprecipitation assays (ChIP-chip) to identify direct targets of E2A-PBX1, and we used gene expression arrays of siRNA E2A-PBX1-silenced cells to evaluate changes in expression induced by the fusion protein. Combined ChIP-chip and expression data analysis gave rise to direct and functional targets of E2A-PBX1. Further we observe that the set of ChIP-chip identified E2A-PBX1 targets show a collective down-regulation trend in the E2A-PBX1 silenced samples compared to controls suggesting an activating role of this fusion transcription factor. Our data suggest that the expression of the E2A-PBX1 fusion gene interferes with key regulatory pathways and functions of hematopoietic biology. Among these are members of the WNT and apoptosis/cell cycle control pathways, and thus may comprise an essential driving force for the propagation and maintenance of the leukemic phenotype. These findings may also provide evidence of potentially attractive therapeutic targets.

Houghton OP, Sumathi VP, Loyson SA, McCluggage WG
Myoepithelioma of the ovary: first reported case.
Int J Gynecol Pathol. 2014; 33(2):191-6 [PubMed] Related Publications
A wide variety of neoplasms of varying histogenesis occur within the ovary. We report the first case of a primary ovarian myoepithelioma, a diagnosis made on the basis of the morphologic features coupled with immunoreactivity with epithelial and myoid markers. The tumor had a lobulated appearance with variable architectural patterns including anastomosing cords, trabeculae, and nests of epithelioid to spindled tumor cells within a hyalinised and focally myxoid stroma. Fluorescence in situ hybridization for EWS gene rearrangement and reverse transcriptase polymerase chain reaction for EWSR1-POU5F1 and EWSR1-PBX1, molecular abnormalities which are found in some extrasalivary myoepitheliomas, were negative. In reporting this unique neoplasm, we discuss the wide differential diagnosis generated by the case.

Velu CS, Chaubey A, Phelan JD, et al.
Therapeutic antagonists of microRNAs deplete leukemia-initiating cell activity.
J Clin Invest. 2014; 124(1):222-36 [PubMed] Free Access to Full Article Related Publications
Acute myelogenous leukemia (AML) subtypes that result from oncogenic activation of homeobox (HOX) transcription factors are associated with poor prognosis. The HOXA9 transcription activator and growth factor independent 1 (GFI1) transcriptional repressor compete for occupancy at DNA-binding sites for the regulation of common target genes. We exploited this HOXA9 versus GFI1 antagonism to identify the genes encoding microRNA-21 and microRNA-196b as transcriptional targets of HOX-based leukemia oncoproteins. Therapeutic inhibition of microRNA-21 and microRNA-196b inhibited in vitro leukemic colony forming activity and depleted in vivo leukemia-initiating cell activity of HOX-based leukemias, which led to leukemia-free survival in a murine AML model and delayed disease onset in xenograft models. These data establish microRNA as functional effectors of endogenous HOXA9 and HOX-based leukemia oncoproteins, provide a concise in vivo platform to test RNA therapeutics, and suggest therapeutic value for microRNA antagonists in AML.

Kiyokawa N, Iijima K, Tomita O, et al.
Significance of CD66c expression in childhood acute lymphoblastic leukemia.
Leuk Res. 2014; 38(1):42-8 [PubMed] Related Publications
Upon analyzing 696 childhood B-cell precursor acute lymphoblastic leukemia (BCP-ALL) cases, we identified the characteristics of CD66c expression. In addition to the confirmation of strong correlation with BCR-ABL positivity and hyperdiploid, we further observed that CD66c is frequently expressed in CRLF2-positive (11/15, p<0.01 against chimeric gene-negative) as well as hypodiploid cases (3/4), whereas it is never expressed in ETV6-RUNX1, MLL-AF4, MLL-AF9, MLL-ENL, and E2A-PBX1-positive cases. Although the expression of CD66c itself is not directly linked to the prognosis, the accompanying genetic abnormalities are important prognostic factors for BCP-ALL, indicating the importance of CD66c expression in the initial diagnosis of BCP-ALL.

Gow CH, Guo C, Wang D, et al.
Differential involvement of E2A-corepressor interactions in distinct leukemogenic pathways.
Nucleic Acids Res. 2014; 42(1):137-52 [PubMed] Free Access to Full Article Related Publications
E2A is a member of the E-protein family of transcription factors. Previous studies have reported context-dependent regulation of E2A-dependent transcription. For example, whereas the E2A portion of the E2A-Pbx1 leukemia fusion protein mediates robust transcriptional activation in t(1;19) acute lymphoblastic leukemia, the transcriptional activity of wild-type E2A is silenced by high levels of corepressors, such as the AML1-ETO fusion protein in t(8;21) acute myeloid leukemia and ETO-2 in hematopoietic cells. Here, we show that, unlike the HEB E-protein, the activation domain 1 (AD1) of E2A has specifically reduced corepressor interaction due to E2A-specific amino acid changes in the p300/CBP and ETO target motif. Replacing E2A-AD1 with HEB-AD1 abolished the ability of E2A-Pbx1 to activate target genes and to induce cell transformation. On the other hand, the weak E2A-AD1-corepressor interaction imposes a critical importance on another ETO-interacting domain, downstream ETO-interacting sequence (DES), for corepressor-mediated repression. Deletion of DES abrogates silencing of E2A activity by AML1-ETO in t(8;21) leukemia cells or by ETO-2 in normal hematopoietic cells. Our results reveal an E2A-specific mechanism important for its context-dependent activation and repression function, and provide the first evidence for the differential involvement of E2A-corepressor interactions in distinct leukemogenic pathways.

Hassawi M, Shestakova EA, Fournier M, et al.
Hoxa9 collaborates with E2A-PBX1 in mouse B cell leukemia in association with Flt3 activation and decrease of B cell gene expression.
Dev Dyn. 2014; 243(1):145-58 [PubMed] Related Publications
BACKGROUND: The fusion protein E2A-PBX1 induces pediatric B cell leukemia in human. Previously, we reported oncogenic interactions between homeobox (Hox) genes and E2A-PBX1 in murine T cell leukemia. A proviral insertional mutagenesis screen with our E2A-PBX1 B cell leukemia mouse model identified Hoxa genes as potential collaborators to E2A-PBX1. Here we studied whether Hoxa9 could enhance E2A-PBX1 leukemogenesis.
RESULTS: We show that Hoxa9 confers a proliferative advantage to E2A-PBX1 B cells. Transplantation experiments with E2A-PBX1 transgenic B cells overexpressing Hoxa9 isolated from bone marrow chimeras showed that Hoxa9 accelerates the generation of E2A-PBX1 B cell leukemia, but Hoxa9 is unable to transform B cells alone. Quantitative-reverse transcriptase polymerase chain reaction analysis demonstrated a strong repression of B cell specific genes in these E2A-PBX1/Hoxa9 leukemias in addition to Flt3 activation, indicating inhibition of B cell differentiation in combination with enhanced proliferation. Overexpression of Hoxa9 in established E2A-PBX1 mouse leukemic B cells resulted in a growth advantage in vitro, which was also characterized by an enhanced expression of Flt3.
CONCLUSIONS: we show for the first time that Hoxa9 collaborates with E2A-PBX1 in the oncogenic transformation of B cells in a mouse model that involves Flt3 signaling, which is potentially relevant to human disease.

Marin-Muller C, Li D, Bharadwaj U, et al.
A tumorigenic factor interactome connected through tumor suppressor microRNA-198 in human pancreatic cancer.
Clin Cancer Res. 2013; 19(21):5901-13 [PubMed] Free Access to Full Article Related Publications
PURPOSE: The majority of pancreatic cancers overexpress mesothelin (MSLN), which contributes to enhanced proliferation, invasion, and migration. However, the MSLN regulatory network is still unclear. Here, we investigated the regulation of a panel of tumorigenic factors and explored the potential of MSLN-regulated miR-198 treatment in vivo.
EXPERIMENTAL DESIGN: The expression and functional regulation of the tumorigenic factors MSLN, NF-κB, and the homeobox transcription factors (TF) POU2F2 (OCT-2), Pre-B-cell leukemia homeobox factor 1 (PBX-1), valosin-containing protein (VCP), and miR-198 were studied in pancreatic cancer cell lines, patient tumor samples, and xenograft pancreatic cancer mouse models.
RESULTS: We found that miR-198 is downregulated in pancreatic cancer and is involved in an intricate reciprocal regulatory loop with MSLN, which represses miR-198 through NF-κB-mediated OCT-2 induction. Furthermore, miR-198 repression leads to overexpression of PBX-1 and VCP. The dysregulated PBX-1/VCP axis leads to increased tumorigenicity. Reconstitution of miR-198 in pancreatic cancer cells results in reduced tumor growth, metastasis, and increased survival through direct targeting MSLN, PBX-1, and VCP. Most interestingly, reduced levels of miR-198 in human tissue samples are associated with upregulation of these tumorigenic factors (MSLN, OCT-2, PBX-1, VCP) and predict poor survival. Reduced miR-198 expression links this tumor network signature and prognosticates poor patient outcome. High miR-198 disrupts the network and predicts better prognosis and increased survival.
CONCLUSIONS: miR-198 acts as a central tumor suppressor and modulates the molecular makeup of a critical interactome in pancreatic cancer, indicating a potential prognostic marker signature and the therapeutic potential of attacking this tumorigenic network through a central vantage point.

Carranza C, Granados L, Morales O, et al.
Frequency of the ETV6-RUNX1, BCR-ABL1, TCF3-PBX1, and MLL-AFF1 fusion genes in Guatemalan pediatric acute lymphoblastic leukemia patients and their ethnic associations.
Cancer Genet. 2013; 206(6):227-32 [PubMed] Related Publications
Fusion genes involved in acute lymphoblastic leukemia (ALL) occur mostly due to genetic and environmental factors, and only a limited number of studies have reported any ethnic influence. This study assesses whether an ethnic influence has an effect on the frequency of any of the four fusion genes: BCR-ABL1, ETV6-RUNX1, TCF3-PBX1, and MLL-AFF1 found in ALL. To study this ethnic influence, mononuclear cells were obtained from bone marrow samples from 143 patients with ALL. We performed RNA extraction and reverse transcription, then assessed the quality of the cDNA by amplifying the ABL1 control gene, and finally evaluated the presence of the four transcripts by multiplex polymerase chain reaction. We found 10 patients who had the BCR-ABL1 fusion gene (7%); 3 patients (2%) were TCF3-PBX1 positive; and 6 patients (4.5%) were ETV6-RUNX1 positive. The incidence of this last fusion gene is quite low when compared to the values reported in most countries. The low incidence of the ETV6-RUNX1 fusion gene found in Guatemala matches the incidence rates that have been reported in Spain and Indian Romani. Since it is known that an ethnic resemblance exists among these three populations, as shown by ancestral marker studies, the ALL data suggests an ethnic influence on the occurrence and frequency of this particular fusion gene.

Mo ML, Chen Z, Zhou HM, et al.
Detection of E2A-PBX1 fusion transcripts in human non-small-cell lung cancer.
J Exp Clin Cancer Res. 2013; 32:29 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: E2A-PBX1 fusion gene caused by t(1;19)(q23;p13), has been well characterized in acute lymphoid leukemia (ALL). There is no report on E2A-PBX1 fusion transcripts in non-small-cell lung cancer (NSCLC).
METHODS: We used polymerase chain reaction (PCR) to detect E2A-PBX1 fusion transcripts in human NSCLC tissue specimens and cell lines. We analyzed correlation of E2A-PBX1 fusion transcripts with clinical outcomes in 76 patients with adenocarcinoma in situ (AIS) and other subgroups. We compared mutation status of k-ras, p53 and EGFR in 22 patients with E2A-PBX1 fusion transcripts.
RESULTS: We detected E2A-PBX1 transcripts in 23 of 184 (12.5%) NSCLC tissue specimens and 3 of 13 (23.1%) NSCLC cell lines. Presence of E2A-PBX1 fusion transcripts correlated with smoking status in female patients (P=0.048), AIS histology (P=0.006) and tumor size (P=0.026). The overall survival was associated with gender among AIS patients (P=0.0378) and AIS patients without E2A-PBX1 fusion transcripts (P=0.0345), but not among AIS patients with E2A-PBX1 fusion transcripts (P=0.6401). The overall survival was also associated with status of E2A-PBX1 fusion transcripts among AIS stage IA patients (P=0.0363) and AIS stage IA female patients (P=0.0174). In addition, among the 22 patients with E2A-PBX1 fusion transcripts, 12 (54.5%) patients including all four non-smokers, showed no common mutations in k-ras, p53 and EGFR.
CONCLUSIONS: E2A-PBX1 fusion gene caused by t(1;19)(q23;p13) may be a common genetic change in AIS and a survival determinant for female AIS patients at early stage.

Kurzawa P, Kattapuram S, Hornicek FJ, et al.
Primary myoepithelioma of bone: a report of 8 cases.
Am J Surg Pathol. 2013; 37(7):960-8 [PubMed] Related Publications
The clinical and pathologic features of 8 primary myoepitheliomas of bone were analyzed. There were 5 female and 3 male patients who ranged in age from 16 to 49 (mean, 33.5) years. Three tumors arose in the ilium, 2 in the tibia, and 1 each in the maxilla, sacrum, and L1 vertebral body. Microscopically, the tumors had a solid, lobulated, reticular, or storiform growth pattern and were predominantly composed of spindle-shaped cells arranged in intersecting fascicles with eosinophilic cytoplasm. The round to polygonal epithelioid cells were arranged randomly or formed small clusters and contained variable amounts of eosinophilic or clear cytoplasm. Immunohistochemically, all the tumors were positive for vimentin and S100 protein, and 7 were positive for epithelial membrane antigen. No tumors were positive for keratin (AE1.3/CAM5.2). Smooth muscle actin was positive in 3 tumors and negative in 4, whereas desmin was negative in all 7 tumors tested. Nuclear staining for p63 was negative in 3 tested tumors. Staining for GFAP and CD34 was performed on 4 and 5 tumors, respectively, and all showed no expression. Fluorescence in situ hybridization for EWSR1 rearrangement was performed in 7 tumors. Five tumors (71%) showed the presence of EWSR1 gene rearrangement, and 2 were negative. Cytogenetic studies conducted on 1 tumor showed 46,XY,t(1;22)(q21;q12) associated with EWSR1-PBX1 fusion. Surgical procedures included curettage in 3 patients, resection in 3 patients, and 2 patients only had an open biopsy. Follow-up information was available for 4 patients; all remain free of disease with no recurrence. Although experience with primary myoepithelioma of bone is limited, histologically, banal tumors appear to behave in a benign manner, and conservative surgery appears to be sufficient treatment. Immunohistochemical and molecular analyses are helpful in their accurate identification.

Jo VY, Antonescu CR, Zhang L, et al.
Cutaneous syncytial myoepithelioma: clinicopathologic characterization in a series of 38 cases.
Am J Surg Pathol. 2013; 37(5):710-8 [PubMed] Free Access to Full Article Related Publications
Cutaneous myoepithelial tumors demonstrate heterogenous morphologic and immunophenotypic features. We previously described, in brief, 7 cases of cutaneous myoepithelioma showing solid syncytial growth of ovoid, spindled, or histiocytoid cells. We now present the clinicopathologic features in a series of 38 cases of this distinctive syncytial variant, which were diagnosed between 1997 and 2012 (mostly seen in consultation). There were 27 men and 11 women, with a median age of 39 years (range, 2 mo to 74 y). Primary anatomic sites were the upper extremity (11, including 2 on the hand), upper limb girdle (3), lower extremity (14; 3 on the foot), back (6), face (2), chest (1), and buttock (1); the typical presentation was as either a polypoid or papular lesion. Tumors were well circumscribed and centered in the dermis and ranged in size from 0.3 to 2.7 cm (median 0.8 cm). Microscopically all tumors showed a solid sheet-like growth of uniformly sized ovoid to spindled or histiocytoid cells with palely eosinophilic syncytial cytoplasm. Nuclei were vesicular with fine chromatin and small or inconspicuous nucleoli and exhibited minimal to no atypia. Mitoses ranged from 0 to 4 per 10 HPF; 28 tumors showed no mitoses. Necrosis and lymphovascular invasion were consistently absent. Adipocytic metaplasia, appearing as superficial fat entrapped within the tumor, was seen in 12 cases. Chondro-osseous differentiation was seen in 1 tumor. All tumors examined were diffusely positive for EMA, and the majority showed diffuse staining for S-100 protein (5 showing focal staining). Keratin staining was focal in 1 of 33 tumors and seen in rare cells in 3 other cases. There was also positivity for GFAP (14/33), SMA (9/13), and p63 (6/11). Most lesions were treated by local excision. The majority of tumors tested (14/17; 82%) were positive by fluorescence in situ hybridization for EWSR1 gene rearrangement; testing for potential fusion partners (PBX1, ZNF444, POU5F1, DUX4, ATF1, CREB1, NR4A3, DDIT3, and NFATc2) was negative in all EWSR1-rearranged tumors. No FUS gene rearrangement was detected in 2 tumors lacking EWSR1 rearrangement. Follow-up information is available for 21 patients (mean follow-up 15 mo). One patient with a positive deep margin developed a local recurrence 51 months after initial biopsy. All other patients with available follow-up information, including 11 who had positive deep margins, are alive with no evidence of disease and no reported metastases. In summary, cutaneous syncytial myoepithelioma is a morphologically distinct variant that more frequently affects men, occurs over a wide age range, and usually presents on the extremities. Tumors are positive for S-100 protein and EMA, and, unlike most myoepithelial neoplasms, keratin staining is infrequent. EWSR1 gene rearrangement is present in nearly all tumors tested and likely involves a novel fusion partner. Prior reports describe some risk of recurrence and metastasis for cutaneous myoepithelial tumors; however, the syncytial variant appears to behave in a benign manner and only rarely recurs locally.

Martinez-Mancilla M, Rodriguez-Aguirre I, Tejocote-Romero I, et al.
Clinical relevance of the fusion transcripts distribution pattern in mexican children with acute lymphoblastic leukemia.
J Pediatr Hematol Oncol. 2013; 35(3):170-3 [PubMed] Related Publications
Chromosomal translocation-generated fusion genes in childhood acute lymphoblastic leukemia (ALL) are well-known indicators of prognostic outcome. This study was conducted to establish the clinical relevance of the fusion genes distribution pattern in Mexican children with newly diagnosed ALL. Multiplex RT-PCR assays were used to detect 4 commonest fusion transcripts in 261 Mexican children with B-cell precursor ALL aged 1 to 14 years old, comparing differences in the distribution of the patients between molecular subgroups to a common collection of clinical parameters. We documented a 13% significant proportion of all patients who are more than 10 years of age, harboring fusion transcripts associated with leukocytosis and poor response to remission-induction chemotherapy, than those negative children for chimeric transcripts (P<0.001). Most notable observation was identified a significant number of e2a-pbx1-positive patients who showed a more aggressive disease at diagnosis. As presented here, this report gives an overview of the clinical implications of the fusion gene positivity in Mexican children with ALL in the context of traditional risk stratification variables. Our data support the existence of important ethnic and geographic differences in Mexican population.

Petrini I, Wang Y, Zucali PA, et al.
Copy number aberrations of genes regulating normal thymus development in thymic epithelial tumors.
Clin Cancer Res. 2013; 19(8):1960-71 [PubMed] Free Access to Full Article Related Publications
PURPOSES: To determine whether the deregulation of genes relevant for normal thymus development can contribute to the biology of thymic epithelial tumors (TET).
EXPERIMENTAL DESIGN: Using array comparative genomic hybridization, we evaluated the copy number aberrations of genes regulating thymus development. The expression of genes most commonly involved in copy number aberrations was evaluated by immunohistochemistry and correlated with patients' outcome. Correlation between FOXC1 copy number loss and gene expression was determined in a confirmation cohort. Cell lines were used to test the role of FOXC1 in tumors.
RESULTS: Among 31 thymus development-related genes, PBX1 copy number gain and FOXC1 copy number loss were presented in 43.0% and 39.5% of the tumors, respectively. Immunohistochemistry on a series of 132 TETs, including those evaluated by comparative genomic hybridization, revealed a correlation between protein expression and copy number status only for FOXC1 but not for PBX1. Patients with FOXC1-negative tumors had a shorter time to progression and a trend for a shorter disease-related survival. The correlation between FOXC1 copy number loss and mRNA expression was confirmed in a separate cohort of 27 TETs. Ectopic FOXC1 expression attenuated anchorage-independent cell growth and cell migration in vitro.
CONCLUSION: Our data support a tumor suppressor role of FOXC1 in TETs.

Awan T, Iqbal Z, Aleem A, et al.
Five most common prognostically important fusion oncogenes are detected in the majority of Pakistani pediatric acute lymphoblastic leukemia patients and are strongly associated with disease biology and treatment outcome.
Asian Pac J Cancer Prev. 2012; 13(11):5469-75 [PubMed] Related Publications
BACKGROUND AND OBJECTIVES: Acute lymphoblastic leukemia (ALL) is a complex genetic disease involving many fusion oncogenes (FO) having prognostic significance. The frequency of various FO can vary in different ethnic groups, with important implications for prognosis, drug selection and treatment outcome.
METHOD: We studied fusion oncogenes in 101 pediatric ALL patients using interphase FISH and RT-PCR, and their associations with clinical features and treatment outcome.
RESULTS: Five most common fusion genes i.e. BCR-ABL t (22; 9), TCF3-PBX1 (t 1; 19), ETV6-RUNX1 (t 12; 21), MLL-AF4 (t 4; 11) and SIL-TAL1 (del 1p32) were found in 89/101 (88.1%) patients. Frequency of BCR-ABL was 44.5% (45/101). BCR-ABL positive patients had a significantly lower survival (43.7±4.24 weeks) and higher white cell count as compared to others, except patients with MLL-AF4. The highest relapse-free survival was documented with ETV6-RUNX1 (14.2 months) followed closely by those cases in which no gene was detected (13.100). RFS with BCR-ABL, MLL-AF4, TCF3-PBX1 and SIL-TAL1 was less than 10 months (8.0, 3.6, 5.5 and 8.1 months, respectively).
CONCLUSIONS: This is the first study from Pakistan correlating molecular markers with disease biology and treatment outcome in pediatric ALL. It revealed the highest reported frequency of BCR-ABL FO in pediatric ALL, associated with poor overall survival. Our data indicate an immediate need for incorporation of tyrosine kinase inhibitors in the treatment of BCR-ABL+ pediatric ALL in this population and the development of facilities for stem cell transplantation.

Dave H, Anver MR, Butcher DO, et al.
Restricted cell surface expression of receptor tyrosine kinase ROR1 in pediatric B-lineage acute lymphoblastic leukemia suggests targetability with therapeutic monoclonal antibodies.
PLoS One. 2012; 7(12):e52655 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Despite high cure rates for pediatric B-lineage acute lymphoblastic leukemia (B-ALL), short-term and long-term toxicities and chemoresistance are shortcomings of standard chemotherapy. Immunotherapy and chemoimmunotherapy based on monoclonal antibodies (mAbs) that target cell surface antigens with restricted expression in pediatric B-ALL may offer the potential to reduce toxicities and prevent or overcome chemoresistance. The receptor tyrosine kinase ROR1 has emerged as a candidate for mAb targeting in select B-cell malignancies.
METHODOLOGY AND PRINCIPAL FINDINGS: Using flow cytometry, Western blotting, immunohistochemistry, and confocal immunofluorescence microscopy, we analyzed the cell surface expression of ROR1 across major pediatric ALL subtypes represented by 14 cell lines and 56 primary blasts at diagnosis or relapse as well as in normal adult and pediatric tissues. Cell surface ROR1 expression was found in 45% of pediatric ALL patients, all of which were B-ALL, and was not limited to any particular genotype. All cell lines and primary blasts with E2A-PBX1 translocation and a portion of patients with other high risk genotypes, such as MLL rearrangement, expressed cell surface ROR1. Importantly, cell surface ROR1 expression was found in many of the pediatric B-ALL patients with multiply relapsed and refractory disease and normal karyotype or low risk cytogenetics, such as hyperdiploidy. Notably, cell surface ROR1 was virtually absent in normal adult and pediatric tissues.
CONCLUSIONS AND SIGNIFICANCE: Collectively, this study suggests that ROR1 merits preclinical and clinical investigations as a novel target for mAb-based therapies in pediatric B-ALL. We propose cell surface expression of ROR1 detected by flow cytometry as primary inclusion criterion for pediatric B-ALL patients in future clinical trials of ROR1-targeted therapies.

Li Z, Zhang Z, Li Y, et al.
PBX3 is an important cofactor of HOXA9 in leukemogenesis.
Blood. 2013; 121(8):1422-31 [PubMed] Free Access to Full Article Related Publications
Although PBX proteins are known to increase DNA-binding/transcriptional activity of HOX proteins through their direct binding, the functional importance of their interaction in leukemogenesis is unclear.We recently reported that overexpression of a 4-homeobox-gene signature (ie, PBX3/HOXA7/HOXA9/HOXA11) is an independent predictor of poor survival in patients with cytogenetically abnormal acute myeloid leukemia (CA-AML). Here we show that it is PBX3, but not PBX1 or PBX2, that is consistently coexpressed with HOXA9 in various subtypes of CA-AML, particularly MLL-rearranged AML, and thus appears as a potential pathologic cofactor of HOXA9 in CA-AML. We then show that depletion of endogenous Pbx3 expression by shRNA significantly inhibits MLL-fusion-mediated cell transformation, and coexpressed PBX3 exhibits a significantly synergistic effect with HOXA9 in promoting cell transformation in vitro and leukemogenesis in vivo. Furthermore, as a proof of concept, we show that a small peptide, namely HXR9, which was developed to specifically disrupt the interactions between HOX and PBX proteins, can selectively kill leukemic cells with overexpression of HOXA/PBX3 genes. Collectively, our data suggest that PBX3 is a critical cofactor of HOXA9 in leukemogenesis, and targeting their interaction is a feasible strategy to treat presently therapy resistant CA-AML (eg, MLL-rearranged leukemia) in which HOXA/PBX3 genes are overexpressed.

Liu F, Gao L, Jing Y, et al.
Detection and clinical significance of gene rearrangements in Chinese patients with adult acute lymphoblastic leukemia.
Leuk Lymphoma. 2013; 54(7):1521-6 [PubMed] Related Publications
This study aimed to develop a novel multiplex reverse transcription-nested polymerase chain reaction (RT-nPCR) assay to accurately and effectively detect 10 common gene rearrangements in adult acute lymphoblastic leukemia (ALL) and to examine the clinicopathologic characteristics and other genetic aberrations of patients with ALL expressing different fusion genes. Our RT-nPCR assay had a positive detection rate of 35.15% (90/256) for the 10 fusion genes. BCR-ABL1, FUS-ERG, MLL-AF4, ETV6-RUNX1, E2A-PBX1, dupMLL, MLL-AF10, MLL-ENL, SET-NUP214 and SIL-TAL1 were detected in 36 (14.06%), 14 (5.47%), 14 (5.47%), four (1.56%), four (1.56%), five (1.95%), four (1.56%), two (0.78%), two (0.78%) and five patients (1.95%), respectively. The RT-nPCR results were further confirmed by split-out PCR, and cytogenetic and fluorescence in situ hybridization (FISH) analysis revealed corresponding translocations and fusions in 63 and 74 cases, respectively. JAK2 and IKZF1 mutations were commonly detected in patients with BCR-ABL1 ALL, and HOX overexpression was highly correlated with MLL fusions and SET-NUP214. This study demonstrates that RT-nPCR is an effective method for identifying 10 gene rearrangements in adult ALL, and it could potentially be developed for diagnostic use and prognostic studies of ALL.

Hutspardol S, Pakakasama S, Kanta K, et al.
Interphase-FISH screening for eight common rearrangements in pediatric B-cell precursor acute lymphoblastic leukemia.
Int J Lab Hematol. 2013; 35(4):406-15 [PubMed] Related Publications
INTRODUCTION: This is the first pilot study to screen multiple common genetic aberrations in B-cell precursor acute lymphoblastic leukemia (BCP-ALL).
METHODS: Thirty-two children with BCP-ALL were investigated for chromosomal rearrangements using interphase fluorescence in situ hybridization (FISH). Eight common translocations and rearrangements, including ETV6-RUNX1, TCF3-PBX1, BCR-ABL1, ETV6, TCF3, MLL, IGH@, and PAX5, were tested for using dual-color DNA probes.
RESULTS: ETV6-RUNX1 was the most frequent translocation detected in 11 children (34.4%). Two patients with BCR-ABL1 (6.3%) and one with TCF3-PBX1 (3.1%) translocations were also observed. Using break-apart probes, 11 children (34.4%) had a positive FISH result for ETV6, two patients for IGH@ (6.3%), one patient for MLL (3.1%), and one patient for PAX5 rearrangements (3.1%). All patients with the ETV6-RUNX1 fusion were also identified by split signals for ETV6. Other abnormalities, including extra copies and deletion of genes, were observed within the range of 3.1-34.4%. Cytogenetics analysis showed a single case each of BCR-ABL1 fusion, MLL, and IGH@ rearrangements (3.1% each). ETV6-RUNX1 fusion and ETV6 split-apart rearrangements were not visible by cytogenetics. Likewise, one each of cases with TCF3-PBX1 fusion and with PAX5 split signal seen by FISH was not visible by cytogenetics.
CONCLUSION: By using 8 FISH probes in conjunction cytogenetics for the detection of common aberrations, interphase FISH enhanced the detection of chromosomal rearrangements in children with BCP-ALL.

Zhu XL, Ai ZH, Wang J, et al.
Weighted gene co-expression network analysis in identification of endometrial cancer prognosis markers.
Asian Pac J Cancer Prev. 2012; 13(9):4607-11 [PubMed] Related Publications
OBJECTIVE: Endometrial cancer (EC) is the most common gynecologic malignancy. Identification of potential biomarkers of EC would be helpful for the detection and monitoring of malignancy, improving clinical outcomes.
METHODS: The Weighted Gene Co-expression Network Analysis method was used to identify prognostic markers for EC in this study. Moreover, underlying molecular mechanisms were characterized by KEGG pathway enrichment and transcriptional regulation analyses.
RESULTS: Seven gene co-expression modules were obtained, but only the turquoise module was positively related with EC stage. Among the genes in the turquoise module, COL5A2 (collagen, type V, alpha 2) could be regulated by PBX (pre-B-cell leukemia homeobox 1)1/2 and HOXB1(homeobox B1) transcription factors to be involved in the focal adhesion pathway; CENP-E (centromere protein E, 312kDa) by E2F4 (E2F transcription factor 4, p107/p130-binding); MYCN (v-myc myelocytomatosis viral related oncogene, neuroblastoma derived [avian]) by PAX5 (paired box 5); and BCL-2 (B-cell CLL/ lymphoma 2) and IGFBP-6 (insulin-like growth factor binding protein 6) by GLI1. They were predicted to be associated with EC progression via Hedgehog signaling and other cancer related-pathways.
CONCLUSIONS: These data on transcriptional regulation may provide a better understanding of molecular mechanisms and clues to potential therapeutic targets in the treatment of EC.

Cimmino L, Aifantis I
Fingerprinting acute leukemia: DNA methylation profiling of B-acute lymphoblastic leukemia.
Cancer Discov. 2012; 2(11):976-8 [PubMed] Free Access to Full Article Related Publications
In this issue of Cancer Discovery, Geng and colleagues report on their use of a combination of promoter cytosine methylation profiling with gene expression and ChIP sequencing to elucidate molecular signatures of adult B-acute lymphoblastic leukemia patient samples with BCR-ABL1, E2A-PBX1, and MLL rearrangements. The unique epigenetic and gene expression signatures of these clinically unfavorable B-ALL subtypes identify novel biomarkers and provide a strong rationale for repurposing existing therapies to treat these molecularly distinct diseases.

Geng H, Brennan S, Milne TA, et al.
Integrative epigenomic analysis identifies biomarkers and therapeutic targets in adult B-acute lymphoblastic leukemia.
Cancer Discov. 2012; 2(11):1004-23 [PubMed] Free Access to Full Article Related Publications
UNLABELLED: Genetic lesions such as BCR-ABL1, E2A-PBX1, and MLL rearrangements (MLLr) are associated with unfavorable outcomes in adult B-cell precursor acute lymphoblastic leukemia (B-ALL). Leukemia oncoproteins may directly or indirectly disrupt cytosine methylation patterning to mediate the malignant phenotype. We postulated that DNA methylation signatures in these aggressive B-ALLs would point toward disease mechanisms and useful biomarkers and therapeutic targets. We therefore conducted DNA methylation and gene expression profiling on a cohort of 215 adult patients with B-ALL enrolled in a single phase III clinical trial (ECOG E2993) and normal control B cells. In BCR-ABL1-positive B-ALLs, aberrant cytosine methylation patterning centered around a cytokine network defined by hypomethylation and overexpression of IL2RA(CD25). The E2993 trial clinical data showed that CD25 expression was strongly associated with a poor outcome in patients with ALL regardless of BCR-ABL1 status, suggesting CD25 as a novel prognostic biomarker for risk stratification in B-ALLs. In E2A-PBX1-positive B-ALLs, aberrant DNA methylation patterning was strongly associated with direct fusion protein binding as shown by the E2A-PBX1 chromatin immunoprecipitation (ChIP) sequencing (ChIP-seq), suggesting that E2A-PBX1 fusion protein directly remodels the epigenome to impose an aggressive B-ALL phenotype. MLLr B-ALL featured prominent cytosine hypomethylation, which was linked with MLL fusion protein binding, H3K79 dimethylation, and transcriptional upregulation, affecting a set of known and newly identified MLL fusion direct targets with oncogenic activity such as FLT3 and BCL6. Notably, BCL6 blockade or loss of function suppressed proliferation and survival of MLLr leukemia cells, suggesting BCL6-targeted therapy as a new therapeutic strategy for MLLr B-ALLs.
SIGNIFICANCE: We conducted the first integrative epigenomic study in adult B-ALLs, as a correlative study to the ECOG E2993 phase III clinical trial. This study links for the first time the direct actions of oncogenic fusion proteins with disruption of epigenetic regulation mediated by cytosine methylation. We identify a novel clinically actionable biomarker in B-ALLs: IL2RA (CD25), which is linked with BCR-ABL1 and an inflammatory signaling network associated with chemotherapy resistance. We show that BCL6 is a novel MLL fusion protein target that is required to maintain the proliferation and survival of primary human adult MLLr cells and provide the basis for a clinical trial with BCL6 inhibitors for patients with MLLr.

Holmlund T, Lindberg MJ, Grander D, Wallberg AE
GCN5 acetylates and regulates the stability of the oncoprotein E2A-PBX1 in acute lymphoblastic leukemia.
Leukemia. 2013; 27(3):578-85 [PubMed] Related Publications
The t(1;19) translocation in pediatric pre-B-cell acute lymphoblastic leukemia (ALL) fuses the genes, which encode the transcriptional activator E2A and homeobox pre-B-cell leukemia transcription factor 1 (PBX1), resulting in expression of the chimeric transcription factor E2A-PBX1. E2A-PBX1 can promote cell transformation both in vitro and in vivo; however, the mechanisms by which E2A-PBX1 contributes to malignancy merit further investigation. In the current work we report, for the first time, a physical and functional interaction between the SPT3-TAFII31-GCN5L acetylase (STAGA) complex and E2A-PBX1. STAGA, and its acetyltransferase subunit GCN5, directly interacted with the E2A portion of E2A-PBX1. GCN5 acetylated E2A-PBX1 and increased the stability of E2A-PBX1 protein in cells. Moreover, the GCN5 inhibitor α-methylene-γ-butyrolactone 3 (MB-3) decreased E2A-PBX1 acetylation and E2A-PBX1 protein levels in leukemic cells, indicating that GCN5 inhibitors have potential value as therapeutic agents for ALL. In addition, we show that the E3 ubiquitin ligase HDM2 potentiates the degradation of E2A-PBX1. We suggest that dynamic regulation of E2A-PBX1 protein levels in vivo has a fundamental role in ALL.

Sabir N, Iqbal Z, Aleem A, et al.
Prognostically significant fusion oncogenes in Pakistani patients with adult acute lymphoblastic leukemia and their association with disease biology and outcome.
Asian Pac J Cancer Prev. 2012; 13(7):3349-55 [PubMed] Related Publications
BACKGROUND AND OBJECTIVES: Chromosomal abnormalities play an important role in genesis of acute lymphoblastic leukemia (ALL) and have prognostic implications. Five major risk stratifying fusion genes in ALL are BCR-ABL, MLL-AF4, ETV6-RUNX11, E2A-PBX1 and SIL-TAL1. This work aimed to detect common chromosomal translocations and associated fusion oncogenes in adult ALL patients and study their relationship with clinical features and treatment outcome.
METHODS: We studied fusion oncogenes in 104 adult ALL patients using RT-PCR and interphase-FISH at diagnosis and their association with clinical characteristics and treatment outcome.
RESULTS: Five most common fusion genes i.e. BCR-ABL (t 9; 22), TCF3-PBX1 (t 1; 19), ETV6-RUNX1 (t 12; 21), MLL-AF4 (t 4; 11) and SIL-TAL1 (Del 1p32) were found in 82/104 (79%) patients. TCF3-PBX1 fusion gene was associated with lymphadenopathy, SIL-TAL positive patients had frequent organomegaly and usually presented with a platelets count of less than 50 x10(9)/l. Survival of patients with fusion gene ETV6-RUNX1 was better when compared to patients harboring other genes. MLL-AF4 and BCR-ABL positivity characterized a subset of adult ALL patients with aggressive clinical behaviour and a poor outcome.
CONCLUSIONS: This is the first study from Pakistan which investigated the frequency of 5 fusion oncogenes in adult ALL patients, and their association with clinical features, treatment response and outcome. Frequencies of some of the oncogenes were different from those reported elsewhere and they appear to be associated with distinct clinical characteristics and treatment outcome. This information will help in the prognostic stratification and risk adapted management of adult ALL patients.

Uckun FM, Qazi S, Dibirdik I, Myers DE
Rational design of an immunoconjugate for selective knock-down of leukemia-specific E2A-PBX1 fusion gene expression in human Pre-B leukemia.
Integr Biol (Camb). 2013; 5(1):122-32 [PubMed] Related Publications
The t(1;19)(q23;p13) is one of the most common chromosomal translocations in acute lymphoblastic leukemia (ALL) and results in production of the transforming oncoprotein E2A-PBX1. Here we first report a novel, biomarker-guided biotherapy strategy for personalized treatment of t(1;19)(+) ALL. A supervised interrogation of the gene expression profiles of primary leukemic cells from a cohort of 207 children with high risk B-lineage ALL identified up-regulated CD19 gene expression as a biomarker for t(1;19)(+) ALL. A disulfide-linked immunoconjugate of a 5-amino-modified 24 mer phosphorothioate anti-sense E2A-PBX1 oligonucleotide (AON) with a mAb specific for a CD19 receptor (αCD19-AON) was prepared as a CD19-directed and leukemia-specific biotherapeutic agent against E2A-PBX1(+) B-lineage ALL. Treatment of E2A-PBX1(+) leukemia cells with low nanomolar concentrations of αCD19-AON resulted in selective depletion of E2A-PBX1 transcripts and caused apoptotic destruction and abrogation of clonogenic growth. Subcutaneously administered αCD19-AON at a total dose level of 93 nmol kg(-1) delivered over 14 days using a micro-osmotic pump more than doubled the leukemia-free survival time of SCID mice in a xenograft model of E2A-PBX1(+) human B-lineage ALL (82.0 ± 1.9 days vs. 37.0 ± 0.1 days, P < 0.0001). Both the AON moiety and the targeting CD19-specific mAb moiety were required for the in vitro as well as in vivo anti-leukemic activity of αCD19-AON. The observed in vitro and in vivo anti-leukemic potency of the αCD19-AON immunoconjugate provides the first preclinical proof-of-principle that t(1;19)(+) high risk B-lineage ALL can be treated with leukemia-specific biotherapeutic agents that knock-down E2A-PBX1 expression.

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