MYB

Gene Summary

Gene:MYB; MYB proto-oncogene, transcription factor
Aliases: efg, Cmyb, c-myb, c-myb_CDS
Location:6q23.3
Summary:This gene encodes a protein with three HTH DNA-binding domains that functions as a transcription regulator. This protein plays an essential role in the regulation of hematopoiesis. This gene may be aberrently expressed or rearranged or undergo translocation in leukemias and lymphomas, and is considered to be an oncogene. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Jan 2016]
Databases:VEGA, OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:transcriptional activator Myb
Source:NCBIAccessed: 16 March, 2017

Ontology:

What does this gene/protein do?
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Cancer Overview

Research Indicators

Publications Per Year (1992-2017)
Graph generated 16 March 2017 using data from PubMed using criteria.

Literature Analysis

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Tag cloud generated 16 March, 2017 using data from PubMed, MeSH and CancerIndex

Latest Publications: MYB (cancer-related)

Ferrarotto R, Heymach JV, Glisson BS
MYB-fusions and other potential actionable targets in adenoid cystic carcinoma.
Curr Opin Oncol. 2016; 28(3):195-200 [PubMed] Related Publications
PURPOSE OF REVIEW: Adenoid cystic carcinoma (ACC) is a rare cancer of the secretory glands, typically originating in the salivary glands of the head and neck. The impact of chemotherapy on survival is unclear and there are no standard-of-care treatments for patients with recurrent or metastatic disease. This article reviews recently completed and ongoing clinical trials for patients with ACC and describes recently identified potentially targetable genomic alterations in this orphan disease.
RECENT FINDINGS: In spite of an overall low mutational burden, genotyping of ACC samples has shed some light about the disease biology. In addition to the frequent translocations involving MYB or MYBL, recurrent alterations in genes involved in chromatin deregulation, FGF, PI3K, NOTCH1, and DNA damage repair pathways have been identified. Many of these genomic alterations are targetable and drug screening is ongoing in genotyped ACC patient-derived murine xenografts.
SUMMARY: Clinical studies with targeted agents in unselected ACC patients have not been promising thus far. The identification of potential driver oncogenes suggests that targeted therapy might be effective in molecularly-defined patient subgroups and merits investigation in future clinical studies.

Yang IP, Tsai HL, Huang CW, et al.
High blood sugar levels significantly impact the prognosis of colorectal cancer patients through down-regulation of microRNA-16 by targeting Myb and VEGFR2.
Oncotarget. 2016; 7(14):18837-50 [PubMed] Free Access to Full Article Related Publications
The high prevalence of type 2 diabetes mellitus in colorectal cancer patients is a crucial public health issue worldwide. The deregulation of microRNAs has been shown to be associated with the progression of CRC; however, the effects of high blood sugar levels on miR deregulation and, in turn, CRC remain unexplored. In this study, 520 CRC patients were classified into two groups according to their blood sugar levels (≧110 or <110 mg/dL). Clinicopathologic features, clinical outcomes, and serum miR-16 levels of the two groups were then analyzed, while cell cycles, cell proliferation, migration, and cellular miR-16 expression were investigated via D-(+)-glucose administration. Additionally, the target genes of miR-16 were identified. Through multivariate analysis, both the disease-free survival and overall survival of the CRC patients were found to be associated with the UICC stage, perineural invasion, and blood glucose levels (P < 0.05). Serum miR-16 levels were significantly lower in the high blood glucose patients than in the normal blood glucose patients (P = 0.0329). With D-(+)-glucose administration, the proliferation and migration of CRC cells in vitro increased remarkably (P < 0.05), while their accumulation in the G1 phase decreased significantly. Cellular miR-16 expression was suppressed by D-(+)-glucose administration. The expression levels of two target genes, Myb and VEGFR2, were affected significantly by miR-16, while glucose administration inhibited miR-16 expression and enhanced tumor cell proliferation and migration. Hyperglycemia can impact the clinical outcomes of CRC patients, likely by inhibiting miR-16 expression and the expression of its downstream genes Myb and VEGFR2.

Tichý M, Knopfová L, Jarkovský J, et al.
Overexpression of c-Myb is associated with suppression of distant metastases in colorectal carcinoma.
Tumour Biol. 2016; 37(8):10723-9 [PubMed] Related Publications
The MYB gene codes for the c-Myb transcription factor maintaining proliferation of colon epithelial progenitors, thus controlling colon development and homeostasis. This gene is overexpressed in early phases of colorectal cancer (CRC) tumorigenesis. The aim of this study was to examine the expression of c-Myb in CRC tissue samples both at the messenger RNA (mRNA) and protein levels and to evaluate their associations with clinicopathological characteristics in a group of 108 CRC patients. Statistically significant negative association was found between the frequency of the c-Myb-positive tumor cells assessed by immunohistochemistry and the presence of distant metastases (p < 0.01) but not tumor differentiation, tumor stage, lymph node involvement, vascular invasion, tumor localization, age, and gender of the patients. Although the c-Myb protein level in the tumor tissue correlated with its mRNA level, no significant association between MYB mRNA and any clinicopathological characteristics was observed. We conclude that albeit overexpression of c-Myb is considered as an important factor contributing to early phases of CRC tumorigenesis, it may later have negative effect on tumor cell dissemination as observed recently in breast cancer as well. Further studies are required to explain the role of c-Myb during formation of CRC distant metastases.

Gonda TJ, Ramsay RG
Adenoid Cystic Carcinoma Can Be Driven by MYB or MYBL1 Rearrangements: New Insights into MYB and Tumor Biology.
Cancer Discov. 2016; 6(2):125-7 [PubMed] Related Publications
A majority of adenoid cystic carcinomas (AdCC)-rare tumors of the salivary gland and some other organs-have recently been found to be driven by chromosomal translocations resulting in MYB-NFIB fusions. Brayer and colleagues and Mitani and colleagues have now reported that AdCCs can alternatively be driven by similar rearrangements involving a second MYB family gene, MYBL1, and that these two drivers act in remarkably similar ways.

Argyris PP, Wetzel SL, Greipp P, et al.
Clinical utility of myb rearrangement detection and p63/p40 immunophenotyping in the diagnosis of adenoid cystic carcinoma of minor salivary glands: a pilot study.
Oral Surg Oral Med Oral Pathol Oral Radiol. 2016; 121(3):282-9 [PubMed] Related Publications
OBJECTIVES: MYB rearrangement is observed in approximately 28% to 86% of adenoid cystic carcinomas (ACCs). Also, ACC features a p63+/p40+ immunophenotype in greater than 90% of cases, compared with p63+/p40- polymorphous low-grade adenocarcinoma (PLGA). Our aim was to investigate the incidence of (1) MYB rearrangement and (2) p63/p40 immunoreactivity in ACC and PLGA of minor salivary glands (MSGs).
STUDY DESIGN: Seven cases of ACC as well as five of PLGA were evaluated by using a MYB (6 q23.3) break-apart fluorescence in situ hybridization (FISH) probe. In addition, all cases were immunohistochemically stained with p63 and p40 antibodies.
RESULTS: All five successfully hybridized ACCs featured MYB rearrangement, whereas PLGAs did not show MYB rearrangement. Interestingly, one case of PLGA demonstrated a single intact copy of MYB in greater than 88% of the neoplastic cells. All ACCs exhibited consistent p63+/p40+ staining, whereas PLGAs demonstrated a p63+/p40- immunophenotype.
CONCLUSIONS: (1) MYB rearrangement is encountered in ACCs but not PLGAs of MSGs; (2) MYB aberrations, for example, monosomy or deletion, can be seen in PLGAs; (3) combined p63/p40 immunostaining can be used to differentiate ACC from PLGA in incisionally biopsied specimens; and (4) performance of either FISH or p63/p40 immunohistochemistry is expected to be able to confirm the diagnosis of ACC or PLGA in small intraoral biopsies, since both techniques appeared to be diagnostically accurate in this pilot study.

Srivastava SK, Bhardwaj A, Arora S, et al.
MYB is a novel regulator of pancreatic tumour growth and metastasis.
Br J Cancer. 2015; 113(12):1694-703 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: MYB encodes for a transcription factor regulating the expression of a wide array of genes involved in cellular functions. It is reported to be amplified in a sub-set of pancreatic cancer (PC) cases; however, its pathobiological association has remained unclear thus far.
METHODS: Expression of MYB and other cellular proteins was analysed by immunoblot or qRT-PCR analyses. MYB was stably overexpressed in non-expressing (BxPC3) and silenced in highly expressing (MiaPaCa and Panc1) PC cells. Effect on growth was analysed by automated cell counting at 24-h interval. Cell-cycle progression and apoptotic indices of PC cells with altered MYB expression were measured through flow cytometry upon staining with respective biomarkers. Cell motility/invasion was examined in a Boyden's chamber assay using non-coated or Matrigel-coated membranes. Effect on tumorigenicity and metastatic potential was examined by non-invasive imaging and through end-point measurements of luciferase-tagged MYB-altered PC implanted in the pancreas of nude mice.
RESULTS: MYB was aberrantly expressed in all malignant cases of pancreas, whereas remained undetectable in normal pancreas. All the tested established PC cell lines except BxPC3 also exhibited MYB expression. Forced expression of MYB in BxPC3 cells promoted their growth, cell-cycle progression, survival and malignant behaviour, whereas its silencing in MiaPaCa and Panc1 cells produced converse effects. More importantly, ectopic MYB expression was sufficient to confer tumorigenic and metastatic capabilities to non-tumorigenic BxPC3 cells, while its silencing resulted in significant loss of the same in MYB-overexpressing cells as demonstrated in orthotopic mouse model. We also identified several MYB-regulated genes in PC cells that might potentially mediate its effect on tumour growth and metastasis.
CONCLUSIONS: MYB is aberrantly overexpressed in PC cells and acts as a key determinant of pancreatic tumour growth and metastasis.

Giotopoulos G, van der Weyden L, Osaki H, et al.
A novel mouse model identifies cooperating mutations and therapeutic targets critical for chronic myeloid leukemia progression.
J Exp Med. 2015; 212(10):1551-69 [PubMed] Free Access to Full Article Related Publications
The introduction of highly selective ABL-tyrosine kinase inhibitors (TKIs) has revolutionized therapy for chronic myeloid leukemia (CML). However, TKIs are only efficacious in the chronic phase of the disease and effective therapies for TKI-refractory CML, or after progression to blast crisis (BC), are lacking. Whereas the chronic phase of CML is dependent on BCR-ABL, additional mutations are required for progression to BC. However, the identity of these mutations and the pathways they affect are poorly understood, hampering our ability to identify therapeutic targets and improve outcomes. Here, we describe a novel mouse model that allows identification of mechanisms of BC progression in an unbiased and tractable manner, using transposon-based insertional mutagenesis on the background of chronic phase CML. Our BC model is the first to faithfully recapitulate the phenotype, cellular and molecular biology of human CML progression. We report a heterogeneous and unique pattern of insertions identifying known and novel candidate genes and demonstrate that these pathways drive disease progression and provide potential targets for novel therapeutic strategies. Our model greatly informs the biology of CML progression and provides a potent resource for the development of candidate therapies to improve the dismal outcomes in this highly aggressive disease.

Martelotto LG, De Filippo MR, Ng CK, et al.
Genomic landscape of adenoid cystic carcinoma of the breast.
J Pathol. 2015; 237(2):179-89 [PubMed] Free Access to Full Article Related Publications
Adenoid cystic carcinoma (AdCC) is a rare type of triple-negative breast cancer (TNBC) characterized by the presence of the MYB-NFIB fusion gene. The molecular underpinning of breast AdCCs other than the MYB-NFIB fusion gene remains largely unexplored. Here we sought to define the repertoire of somatic genetic alterations of breast AdCCs. We performed whole-exome sequencing, followed by orthogonal validation, of 12 breast AdCCs to determine the landscape of somatic mutations and gene copy number alterations. Fluorescence in situ hybridization and reverse-transcription PCR were used to define the presence of MYB gene rearrangements and MYB-NFIB chimeric transcripts. Unlike common forms of TNBC, we found that AdCCs have a low mutation rate (0.27 non-silent mutations/Mb), lack mutations in TP53 and PIK3CA and display a heterogeneous constellation of known cancer genes affected by somatic mutations, including MYB, BRAF, FBXW7, SMARCA5, SF3B1 and FGFR2. MYB and TLN2 were affected by somatic mutations in two cases each. Akin to salivary gland AdCCs, breast AdCCs were found to harbour mutations targeting chromatin remodelling, cell adhesion, RNA biology, ubiquitination and canonical signalling pathway genes. We observed that, although breast AdCCs had rather simple genomes, they likely display intra-tumour genetic heterogeneity at diagnosis. Taken together, these findings demonstrate that the mutational burden and mutational repertoire of breast AdCCs are more similar to those of salivary gland AdCCs than to those of other types of TNBCs, emphasizing the importance of histological subtyping of TNBCs. Furthermore, our data provide direct evidence that AdCCs harbour a distinctive mutational landscape and genomic structure, irrespective of the disease site of origin.

Bishop JA, Yonescu R, Epstein JI, Westra WH
A subset of prostatic basal cell carcinomas harbor the MYB rearrangement of adenoid cystic carcinoma.
Hum Pathol. 2015; 46(8):1204-8 [PubMed] Related Publications
Adenoid cystic carcinoma (ACC) is a basaloid tumor consisting of myoepithelial and ductal cells typically arranged in a cribriform pattern. Adenoid cystic carcinoma is generally regarded as a form of salivary gland carcinoma, but it can arise from sites unassociated with salivary tissue. A rare form of prostate carcinoma exhibits ACC-like features; it is no longer regarded as a true ACC but rather as prostatic basal cell carcinoma (PBCC) and within the spectrum of basaloid prostatic proliferations. True ACCs often harbor MYB translocations resulting in the MYB-NFIB fusion protein. MYB analysis could clarify the true nature of prostatic carcinomas that exhibit ACC features and thus help refine the classification of prostatic basaloid proliferations. Twelve PBCCs were identified from the pathology consultation files of Johns Hopkins Hospital. The histopathologic features were reviewed, and break-apart fluorescence in situ hybridization for MYB was performed. All 12 cases exhibited prominent basaloid histology. Four were purely solid, 7 exhibited a cribriform pattern reminiscent of salivary ACC, and 1 had a mixed pattern. The MYB rearrangement was detected in 2 (29%) of 7 ACC-like carcinomas but in none (0%) of the 5 PBCCs with a prominent solid pattern. True ACCs can arise in the prostate as is evidenced by the presence of the characteristic MYB rearrangement. When dealing with malignant basaloid proliferations in the prostate, recommendations to consolidate ACCs with other tumor types may need to be reassessed, particularly in light of the rapidly advancing field of biologic therapy where the identification of tumor-specific genetic alterations presents novel therapeutic targets.

North JP, McCalmont TH, Fehr A, et al.
Detection of MYB Alterations and Other Immunohistochemical Markers in Primary Cutaneous Adenoid Cystic Carcinoma.
Am J Surg Pathol. 2015; 39(10):1347-56 [PubMed] Related Publications
Adenoid cystic carcinoma (ACC) can arise in several organs, and prognosis is highly dependent on the primary tumor site. Primary cutaneous ACC has an excellent prognosis compared with salivary or lacrimal ACC. Activation of MYB by gene fusion or other mechanisms has been found in salivary, breast, and lacrimal ACCs but has not been described in cutaneous ACC. We analyzed the histopathologic and immunohistochemical features of 19 primary cutaneous ACCs, 2 periorbital ACCs, and 12 salivary gland ACCs and assessed for MYB activation in primary cutaneous ACC by immunohistochemistry and molecular methods. The presence of perineural invasion differed significantly among ACCs of various sites (83% salivary, 50% eyelid, 11% skin, P=0.0002). Over 90% of all ACCs were grade 1 or 2 and exhibited diffuse (>50%) positivity with CD117, SOX-10, and smooth muscle actin immunostains. CK15 and vimentin showed diffuse positivity in 36% and 57% of cutaneous ACCs, respectively, and were negative or only focally positive in all salivary ACCs (P=0.04 and 0.002). Six of the 11 cutaneous and periorbital ACCs tested with reverse transcriptase polymerase chain reaction and/or fluorescence in situ hybridization had MYB rearrangements including 2 cases that expressed MYB-NFIB fusion transcripts. Diffuse expression of MYB protein assessed by immunostaining was present in 8 of 9 cutaneous ACCs, including cases both with and without MYB rearrangements. These results indicate that cutaneous ACCs possess the same types of MYB alterations as ACCs of other anatomic sites. Vimentin and CK15 appear to have some discriminatory value in differentiating between primary cutaneous and salivary gland ACCs.

Tapper W, Jones AV, Kralovics R, et al.
Genetic variation at MECOM, TERT, JAK2 and HBS1L-MYB predisposes to myeloproliferative neoplasms.
Nat Commun. 2015; 6:6691 [PubMed] Free Access to Full Article Related Publications
Clonal proliferation in myeloproliferative neoplasms (MPN) is driven by somatic mutations in JAK2, CALR or MPL, but the contribution of inherited factors is poorly characterized. Using a three-stage genome-wide association study of 3,437 MPN cases and 10,083 controls, we identify two SNPs with genome-wide significance in JAK2(V617F)-negative MPN: rs12339666 (JAK2; meta-analysis P=1.27 × 10(-10)) and rs2201862 (MECOM; meta-analysis P=1.96 × 10(-9)). Two additional SNPs, rs2736100 (TERT) and rs9376092 (HBS1L/MYB), achieve genome-wide significance when including JAK2(V617F)-positive cases. rs9376092 has a stronger effect in JAK2(V617F)-negative cases with CALR and/or MPL mutations (Breslow-Day P=4.5 × 10(-7)), whereas in JAK2(V617F)-positive cases rs9376092 associates with essential thrombocythemia (ET) rather than polycythemia vera (allelic χ(2) P=7.3 × 10(-7)). Reduced MYB expression, previously linked to development of an ET-like disease in model systems, associates with rs9376092 in normal myeloid cells. These findings demonstrate that multiple germline variants predispose to MPN and link constitutional differences in MYB expression to disease phenotype.

Gao R, Cao C, Zhang M, et al.
A unifying gene signature for adenoid cystic cancer identifies parallel MYB-dependent and MYB-independent therapeutic targets.
Oncotarget. 2014; 5(24):12528-42 [PubMed] Free Access to Full Article Related Publications
MYB activation is proposed to underlie development of adenoid cystic cancer (ACC), an aggressive salivary gland tumor with no effective systemic treatments. To discover druggable targets for ACC, we performed global mRNA/miRNA analyses of 12 ACC with matched normal tissues, and compared these data with 14 mucoepidermoid carcinomas (MEC) and 11 salivary adenocarcinomas (ADC). We detected a unique ACC gene signature of 1160 mRNAs and 22 miRNAs. MYB was the top-scoring gene (18-fold induction), however we observed the same signature in ACC without detectable MYB gene rearrangements. We also found 4 ACC tumors (1 among our 12 cases and 3 from public databases) with negligible MYB expression that retained the same ACC mRNA signature including over-expression of extracellular matrix (ECM) genes. Integration of this signature with somatic mutational analyses suggests that NOTCH1 and RUNX1 participate with MYB to activate ECM elements including the VCAN/HAPLN1 complex. We observed that forced MYB-NFIB expression in human salivary gland cells alters cell morphology and cell adhesion in vitro and depletion of VCAN blocked tumor cell growth of a short-term ACC tumor culture. In summary, we identified a unique ACC signature with parallel MYB-dependent and independent biomarkers and identified VCAN/HAPLN1 complexes as a potential target.

Dillon PM, Chakraborty S, Moskaluk CA, et al.
Adenoid cystic carcinoma: A review of recent advances, molecular targets, and clinical trials.
Head Neck. 2016; 38(4):620-7 [PubMed] Related Publications
BACKGROUND: Adenoid cystic carcinoma (ACC) is a rare tumor of secretory glands. In this study, recent advances in molecular characterization and in therapeutics are reviewed.
METHODS: A search of articles in PubMed and of abstracts from national meetings was performed regarding ACC.
RESULTS: Recent genetic analyses found that recurrent chromosome 6:9 translocations in ACC generate an MYB:NFIB gene fusion resulting in overexpression of the MYB oncoprotein. Several other frequent mutations are recently published that may be relevant for drug development. Several trials of targeted drugs are reviewed. Some agents delay tumor progression, but tumor responses remain rare.
CONCLUSION: ACCs have a characteristic chromosomal translocation, but also frequently pick up additional mutations. Clinical research is limited by the rarity and slow growth of ACC. Several ongoing trials are testing agents that inhibit fibroblast growth factor receptor signaling or other signaling pathways. Novel treatments based on the recently sequenced tumor genome are under development.

Sanghvi VR, Mavrakis KJ, Van der Meulen J, et al.
Characterization of a set of tumor suppressor microRNAs in T cell acute lymphoblastic leukemia.
Sci Signal. 2014; 7(352):ra111 [PubMed] Free Access to Full Article Related Publications
The posttranscriptional control of gene expression by microRNAs (miRNAs) is highly redundant, and compensatory effects limit the consequences of the inactivation of individual miRNAs. This implies that only a few miRNAs can function as effective tumor suppressors. It is also the basis of our strategy to define functionally relevant miRNA target genes that are not under redundant control by other miRNAs. We identified a functionally interconnected group of miRNAs that exhibited a reduced abundance in leukemia cells from patients with T cell acute lymphoblastic leukemia (T-ALL). To pinpoint relevant target genes, we applied a machine learning approach to eliminate genes that were subject to redundant miRNA-mediated control and to identify those genes that were exclusively targeted by tumor-suppressive miRNAs. This strategy revealed the convergence of a small group of tumor suppressor miRNAs on the Myb oncogene, as well as their effects on HBP1, which encodes a transcription factor. The expression of both genes was increased in T-ALL patient samples, and each gene promoted the progression of T-ALL in mice. Hence, our systematic analysis of tumor suppressor miRNA action identified a widespread mechanism of oncogene activation in T-ALL.

Magro CM, Abraham RM, Guo R, et al.
Deep penetrating nevus-like borderline tumors: A unique subset of ambiguous melanocytic tumors with malignant potential and normal cytogenetics.
Eur J Dermatol. 2014 Sep-Oct; 24(5):594-602 [PubMed] Related Publications
BACKGROUND: Deep penetrating nevi (DPN) are a relatively uncommon subtype of melanocytic nevi. A small subset of these lesions exhibit atypical features (cytologic and architectural atypia, mitotic activity) seen in melanoma. These lesions we term the deep penetrating nevus-like borderline tumor. Unequivocal melanomas can show overlapping morphologic features of DPN, which have been termed plexiform melanomas.
PATIENTS AND METHODS: 40 cases of DPN-like borderline tumor were identified along with 6 cases of plexiform melanoma. Clinical follow up was obtained, along with cytogenetic analysis in the form of fluorescent in situ hybridization (FISH) and/or comparative genomic hybridization (CGH).
RESULTS: The DPN-like borderline tumor cases included 24 females and 16 males. Of sentinel lymph node biopsies performed, 1/3 of cases showed lymph node involvement. All patients where an aggressive clinical approach was adopted remain free of disease. All 6 DPN-like borderline tumor cases tested by CGH showed normal cytogenetics, as did 7 of 9 cases tested by FISH. Of the plexiform melanomas, 4/6 patients died of disease. In 3 cases there was morphologic progression from a DPN-like borderline tumor to overt melanoma. In one case of progression, cytogenetics was normal in the DPN-like borderline tumor and then abnormal in the progressed melanoma.
CONCLUSION: DPN-like borderline tumors are melanocytic tumors associated with a high incidence of regional lymph node disease and exhibiting the potential for melanoma progression despite a normal cytogenetic profile. Patients with these lesions should be aggressively managed, with at least complete re-excision and consideration of sentinel node biopsy, regardless of cytogenetic data.

Costa AF, Altemani A, García-Inclán C, et al.
Analysis of MYB oncogene in transformed adenoid cystic carcinomas reveals distinct pathways of tumor progression.
Lab Invest. 2014; 94(6):692-702 [PubMed] Related Publications
Adenoid cystic carcinomas can occasionally undergo dedifferentiation, a phenomenon also referred to as high-grade transformation. However, cases of adenoid cystic carcinomas have been described showing transformation to adenocarcinomas that are not poorly differentiated, indicating that high-grade transformation may not necessarily reflect a more advanced stage of tumor progression, but rather a transformation to another histological form, which may encompass a wide spectrum of carcinomas in terms of aggressiveness. The aim of this study was to gain more insight in the biology of this pathological phenomenon by means of genetic profiling of both histological components. Using microarray comparative genomic hybridization, we compared the genome-wide DNA copy-number changes of the conventional and transformed area of eight adenoid cystic carcinomas with high-grade transformation, comprising four with transformation into moderately differentiated adenocarcinomas and four into poorly differentiated carcinomas. In general, the poorly differentiated carcinoma cases showed a higher total number of copy-number changes than the moderately differentiated adenocarcinoma cases, and this correlated with a worse clinical course. Special attention was given to chromosomal translocation and protein expression of MYB, recently being considered to be an early and major oncogenic event in adenoid cystic carcinomas. Our data showed that the process of high-grade transformation is not always accompanied by an accumulation of genetic alterations; both conventional and transformed components harbored unique genetic alterations, which indicate a parallel progression. Our data further demonstrated that the MYB/NFIB translocation is not necessarily an early event or fundamental for the progression to adenoid cystic carcinoma with high-grade transformation.

Yu L, Ding GF, He C, et al.
MicroRNA-424 is down-regulated in hepatocellular carcinoma and suppresses cell migration and invasion through c-Myb.
PLoS One. 2014; 9(3):e91661 [PubMed] Free Access to Full Article Related Publications
Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related mortality worldwide. MicroRNAs (miRNAs) are important regulators of multiple cellular processes, and the aberrant miRNAs expressions have been observed in different types of cancer including HCC. Their pathysiologic role and their relevance to tumorigenesis are still largely unknown. In this study, we demonstrated the down-regulation of miR-424 in HCC cell lines and tissues by quantitative RT-PCR analyses. Overexpression of miR-424 reduced the HCC cell prolifetation, migration, and invasion. Conversely, inhibiton of miR-424 expression significantly accelerated the cell proliferation, migration, and invasion. In addition, we further identified c-Myb as a functional downstream target of miR-424 by directly targeting the 3'UTR of c-Myb. Furthermore, overexpression of c-Myb impaired miR-424-induced inhibition of proliferation and invasion in HCC cells. Our results demonstrated that miR-424 was involved in tumorigenesis of HCC at least in part by suppression of c-Myb.

Huser CA, Gilroy KL, de Ridder J, et al.
Insertional mutagenesis and deep profiling reveals gene hierarchies and a Myc/p53-dependent bottleneck in lymphomagenesis.
PLoS Genet. 2014; 10(2):e1004167 [PubMed] Free Access to Full Article Related Publications
Retroviral insertional mutagenesis (RIM) is a powerful tool for cancer genomics that was combined in this study with deep sequencing (RIM/DS) to facilitate a comprehensive analysis of lymphoma progression. Transgenic mice expressing two potent collaborating oncogenes in the germ line (CD2-MYC, -Runx2) develop rapid onset tumours that can be accelerated and rendered polyclonal by neonatal Moloney murine leukaemia virus (MoMLV) infection. RIM/DS analysis of 28 polyclonal lymphomas identified 771 common insertion sites (CISs) defining a 'progression network' that encompassed a remarkably large fraction of known MoMLV target genes, with further strong indications of oncogenic selection above the background of MoMLV integration preference. Progression driven by RIM was characterised as a Darwinian process of clonal competition engaging proliferation control networks downstream of cytokine and T-cell receptor signalling. Enhancer mode activation accounted for the most efficiently selected CIS target genes, including Ccr7 as the most prominent of a set of chemokine receptors driving paracrine growth stimulation and lymphoma dissemination. Another large target gene subset including candidate tumour suppressors was disrupted by intragenic insertions. A second RIM/DS screen comparing lymphomas of wild-type and parental transgenics showed that CD2-MYC tumours are virtually dependent on activation of Runx family genes in strong preference to other potent Myc collaborating genes (Gfi1, Notch1). Ikzf1 was identified as a novel collaborating gene for Runx2 and illustrated the interface between integration preference and oncogenic selection. Lymphoma target genes for MoMLV can be classified into (a) a small set of master regulators that confer self-renewal; overcoming p53 and other failsafe pathways and (b) a large group of progression genes that control autonomous proliferation in transformed cells. These findings provide insights into retroviral biology, human cancer genetics and the safety of vector-mediated gene therapy.

Sroczynska P, Cruickshank VA, Bukowski JP, et al.
shRNA screening identifies JMJD1C as being required for leukemia maintenance.
Blood. 2014; 123(12):1870-82 [PubMed] Related Publications
Epigenetic regulatory mechanisms are implicated in the pathogenesis of acute myeloid leukemia (AML) and acute lymphoid leukemia (ALL). Recent progress suggests that proteins involved in epigenetic control are amenable to drug intervention, but little is known about the cancer-specific dependency on epigenetic regulators for cell survival and proliferation. We used a mouse model of human AML induced by the MLL-AF9 fusion oncogene and an epigenetic short hairpin RNA (shRNA) library to screen for novel potential drug targets. As a counter-screen for general toxicity of shRNAs, we used normal mouse bone marrow cells. One of the best candidate drug targets identified in these screens was Jmjd1c. Depletion of Jmjd1c impairs growth and colony formation of mouse MLL-AF9 cells in vitro as well as establishment of leukemia after transplantation. Depletion of JMJD1C impairs expansion and colony formation of human leukemic cell lines, with the strongest effect observed in the MLL-rearranged ALL cell line SEM. In both mouse and human leukemic cells, the growth defect upon JMJD1C depletion appears to be primarily due to increased apoptosis, which implicates JMJD1C as a potential therapeutic target in leukemia.

Vonlanthen J, Okoniewski MJ, Menigatti M, et al.
A comprehensive look at transcription factor gene expression changes in colorectal adenomas.
BMC Cancer. 2014; 14:46 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Biological processes are controlled by transcription networks. Expression changes of transcription factor (TF) genes in precancerous lesions are therefore crucial events in tumorigenesis. Our aim was to obtain a comprehensive picture of these changes in colorectal adenomas.
METHODS: Using a 3-pronged selection procedure, we analyzed transcriptomic data on 34 human tissue samples (17 adenomas and paired samples of normal mucosa, all collected with ethics committee approval and written, informed patient consent) to identify TFs with highly significant tumor-associated gene expression changes whose potential roles in colorectal tumorigenesis have been under-researched. Microarray data were subjected to stringent statistical analysis of TF expression in tumor vs. normal tissues, MetaCore-mediated identification of TF networks displaying enrichment for genes that were differentially expressed in tumors, and a novel quantitative analysis of the publications examining the TF genes' roles in colorectal tumorigenesis.
RESULTS: The 261 TF genes identified with this procedure included DACH1, which plays essential roles in the proper proliferation and differentiation of retinal and leg precursor cell populations in Drosophila melanogaster. Its possible roles in colorectal tumorigenesis are completely unknown, but it was found to be markedly overexpressed (mRNA and protein) in all colorectal adenomas and in most colorectal carcinomas. However, DACH1 expression was absent in some carcinomas, most of which were DNA mismatch-repair deficient. When networks were built using the set of TF genes identified by all three selection procedures, as well as the entire set of transcriptomic changes in adenomas, five hub genes (TGFB1, BIRC5, MYB, NR3C1, and TERT) where identified as putatively crucial components of the adenomatous transformation process.
CONCLUSION: The transcription-regulating network of colorectal adenomas (compared with that of normal colorectal mucosa) is characterized by significantly altered expression of over 250 TF genes, many of which have never been investigated in relation to colorectal tumorigenesis.

Fogelstrand L, Staffas A, Wasslavik C, et al.
Prognostic implications of mutations in NOTCH1 and FBXW7 in childhood T-ALL treated according to the NOPHO ALL-1992 and ALL-2000 protocols.
Pediatr Blood Cancer. 2014; 61(3):424-30 [PubMed] Related Publications
BACKGROUND: In children, T-cell acute lymphoblastic leukemia (T-ALL) has inferior prognosis compared with B-cell precursor ALL. In order to improve survival, individualized treatment strategies and thus risk stratification algorithms are warranted, ideally already at the time of diagnosis.
PROCEDURE: We analyzed the frequency and prognostic implication of mutations in NOTCH1 and FBXW7 in 79 cases of Swedish childhood T-ALL treated according to the Nordic Society of Pediatric Hematology and Oncology (NOPHO) ALL-1992 and ALL-2000 protocols. In a subgroup of patients, we also investigated the functional relevance of NOTCH1 mutations measured as expression of the HES1, MYB, and MYC genes.
RESULTS: Forty-seven of the cases (59%) displayed mutations in NOTCH1 and/or FBXW7. There was no difference in overall (P = 0.14) or event-free survival (EFS) (P = 0.10) in patients with T-ALL with mutation(s) in NOTCH1/FBXW7 compared with patients with T-ALL without mutations in any of these genes. T-ALL carrying NOTCH1 mutations had increased HES1 and MYB mRNA expression (HES1 9.2 ± 1.9 (mean ± SEM), MYB 8.7 ± 0.8 (mean ± SEM)) compared to T-ALL with wild-type NOTCH1 (HES1 1.8 ± 0.7, MYB 5.1 ± 1.2, P = 0.02 and 0.008, respectively). In cases of T-ALL with high HES1 expression, improved overall (P = 0.02) and EFS (P = 0.028) was seen.
CONCLUSIONS: Increased NOTCH activity, reflected by increased HES1 expression, is associated with improved outcome in pediatric T-ALL, but its role as a diagnostic tool or a therapeutic target in future clinical treatment protocols remains to be elucidated.

Pusztaszeri MP, Sadow PM, Ushiku A, et al.
MYB immunostaining is a useful ancillary test for distinguishing adenoid cystic carcinoma from pleomorphic adenoma in fine-needle aspiration biopsy specimens.
Cancer Cytopathol. 2014; 122(4):257-65 [PubMed] Related Publications
BACKGROUND: The distinction between adenoid cystic carcinoma (ACC) and pleomorphic adenoma (PA) on fine-needle aspiration biopsy (FNAB) can be challenging. Recently, a specific translocation t(6;9) involving the v-myb avian myeloblastosis viral oncogene homolog (MYB) and nuclear factor I/B (NFIB) genes was identified in ACCs, in which it contributes to MYB overexpression. The authors investigated the use of MYB immunocytochemistry in FNAB specimens as an ancillary test for the cytologic diagnosis of ACC.
METHODS: The expression of MYB was assessed in alcohol-fixed cytologic smears of histologically confirmed ACCs (n = 20) and PAs (n = 20) using immunocytochemistry. The corresponding ACCs and PAs from formalin-fixed, paraffin embedded surgical resection specimens also were stained immunohistochemically for MYB. The nuclear expression of MYB was assessed semiquantitatively using a scoring system (from 0 to 6) that combined the proportion and the intensity of staining. A score ≥4 was considered positive, and a score ≤3 was considered negative.
RESULTS: On FNAB material, 80% of ACCs (N = 16 of 20) were immunocytochemically positive for MYB. In contrast, all PAs (N = 20 of 20) were negative for MYB (P < .0001). The sensitivity of MYB on FNAB was 80%, and the specificity was 100% relative to PA. Results on corresponding histology were similar to the cytology results; however, there was often a zonal staining pattern with central areas of tumor (range, 20%-90%) that lacked immunoreactivity, thus suggesting that the immunoreactivity was maintained better in alcohol-fixed FNAB material.
CONCLUSIONS: In contrast to PAs, a majority of ACCs are immunocytochemically positive for MYB. The test is more effective using alcohol-fixed FNAB material and is potentially useful for the cytologic distinction of ACC and PA.

Kouno T, de Hoon M, Mar JC, et al.
Temporal dynamics and transcriptional control using single-cell gene expression analysis.
Genome Biol. 2013; 14(10):R118 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Changes in environmental conditions lead to expression variation that manifest at the level of gene regulatory networks. Despite a strong understanding of the role noise plays in synthetic biological systems, it remains unclear how propagation of expression heterogeneity in an endogenous regulatory network is distributed and utilized by cells transitioning through a key developmental event.
RESULTS: Here we investigate the temporal dynamics of a single-cell transcriptional network of 45 transcription factors in THP-1 human myeloid monocytic leukemia cells undergoing differentiation to macrophages. We systematically measure temporal regulation of expression and variation by profiling 120 single cells at eight distinct time points, and infer highly controlled regulatory modules through which signaling operates with stochastic effects. This reveals dynamic and specific rewiring as a cellular strategy for differentiation. The integration of both positive and negative co-expression networks further identifies the proto-oncogene MYB as a network hinge to modulate both the pro- and anti-differentiation pathways.
CONCLUSIONS: Compared to averaged cell populations, temporal single-cell expression profiling provides a much more powerful technique to probe for mechanistic insights underlying cellular differentiation. We believe that our approach will form the basis of novel strategies to study the regulation of transcription at a single-cell level.

Mitani Y, Roberts DB, Fatani H, et al.
MicroRNA profiling of salivary adenoid cystic carcinoma: association of miR-17-92 upregulation with poor outcome.
PLoS One. 2013; 8(6):e66778 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Salivary adenoid cystic carcinoma (ACC) is a rare relentlessly progressive malignant tumor. The molecular events associated with ACC tumorigenesis are poorly understood. Variable microRNAs (miRNA) have been correlated with tumorigenesis of several solid tumors but not in ACC. To investigate the association of miRNAs with the development and/or progression of ACC, we performed a comparative analysis of primary ACC specimens and matched normal samples and a pooled salivary gland standard and correlated the results with clinicopathologic factors and validated selected miRNAs in a separate set of 30 tumors.
METHODS: MiRNA array platform was used for the identification of target miRNAs and the data was subjected to informatics and statistical interrelations. The results were also collected with the MYB-NFIB fusion status and the clinicopathologic features.
RESULTS: Differentially dysregulated miRNAs in ACC were characterized in comparison to normal expression. No significant differences in miRNA expression were found between the MYB-NFIB fusion positive and -negative ACCs. Of the highly dysregulated miRNA in ACC, overexpression of the miR-17 and miR-20a were significantly associated with poor outcome in the screening and validation sets.
CONCLUSION: Our study indicates that the upregulation of miR-17-92 may play a role in the biology of ACC and could be potentially targeted in future therapeutic studies.

von Holstein SL, Fehr A, Persson M, et al.
Adenoid cystic carcinoma of the lacrimal gland: MYB gene activation, genomic imbalances, and clinical characteristics.
Ophthalmology. 2013; 120(10):2130-8 [PubMed] Related Publications
PURPOSE: To investigate genetic alterations in lacrimal gland adenoid cystic carcinomas (ACCs) with emphasis on the MYB-NFIB fusion oncogene and its downstream targets, MYB rearrangements, and copy number alterations in relation to clinical data and survival.
DESIGN: Experimental study.
PARTICIPANTS AND CONTROLS: Fourteen patients with primary lacrimal gland ACC were included. As a control, we also studied the expression of MYB-NFIB in 19 non-ACC lacrimal gland tumors.
METHODS: The expression and identity of MYB-NFIB fusion transcripts were studied using reverse transcriptase polymerase chain reaction (RT-PCR) and nucleotide sequence analyses. Quantitative polymerase chain reaction (PCR) and immunohistochemistry were used to evaluate the expression of MYB/MYB-NFIB target genes. High-resolution array-based comparative genomic hybridization (arrayCGH) and fluorescence in situ hybridization were used to study copy number alterations and MYB rearrangements.
MAIN OUTCOME MEASURES: mRNA or protein expression of MYB-NFIB, MYB, and its down stream targets; copy number alterations; and genomic rearrangements.
RESULTS: The median age of the patients was 43 years (equal gender distribution), and the median time of survival was 8.6 years. The MYB-NFIB fusion was expressed in 7 of 14 ACCs. In contrast, all non-ACC tumors were fusion-negative. All 13 ACCs tested stained positive for the MYB protein, and for the MYB targets KIT and BCL2, 12 were positive for MYC and CCNE1, and 9 were positive for CCNB1. Rearrangements of MYB were detected in 8 of 13 cases, including 2 cases with gain of an apparently intact MYB gene. The arrayCGH analysis revealed recurrent copy number alterations with losses involving 6q23-q27, 12q12-q14.1, and 17p13.3-p12, and gains involving 19q12, 19q13.31-qter, 8q24.13-q24.21, 11q12.3-q14.1, and 6q23.3. Neither MYB-NFIB fusion nor any copy number alteration correlated with survival.
CONCLUSIONS: Lacrimal gland ACCs are frequently positive for the MYB-NFIB fusion, overexpress MYB and its downstream targets, and have genomic profiles characterized by losses involving 6q, 12q, and 17p, and gains involving 19q, 8q, and 11q. Our findings show that lacrimal gland ACCs are genetically and clinically similar to their salivary gland counterparts and that MYB-NFIB is a clinically useful diagnostic biomarker for ACC. Our data also suggest that MYB and its downstream targets are potential therapeutic targets for these tumors.
FINANCIAL DISCLOSURE(S): The author(s) have no proprietary or commercial interest in any materials discussed in this article.

El-Naggar AK, Kaye FJ, Stenman G
The 3rd Salivary Gland Tumor Workshop meeting report.
Head Neck. 2013; 35(8):1057-60 [PubMed] Related Publications

Zhang J, Wu G, Miller CP, et al.
Whole-genome sequencing identifies genetic alterations in pediatric low-grade gliomas.
Nat Genet. 2013; 45(6):602-12 [PubMed] Free Access to Full Article Related Publications
The most common pediatric brain tumors are low-grade gliomas (LGGs). We used whole-genome sequencing to identify multiple new genetic alterations involving BRAF, RAF1, FGFR1, MYB, MYBL1 and genes with histone-related functions, including H3F3A and ATRX, in 39 LGGs and low-grade glioneuronal tumors (LGGNTs). Only a single non-silent somatic alteration was detected in 24 of 39 (62%) tumors. Intragenic duplications of the portion of FGFR1 encoding the tyrosine kinase domain (TKD) and rearrangements of MYB were recurrent and mutually exclusive in 53% of grade II diffuse LGGs. Transplantation of Trp53-null neonatal astrocytes expressing FGFR1 with the duplication involving the TKD into the brains of nude mice generated high-grade astrocytomas with short latency and 100% penetrance. FGFR1 with the duplication induced FGFR1 autophosphorylation and upregulation of the MAPK/ERK and PI3K pathways, which could be blocked by specific inhibitors. Focusing on the therapeutically challenging diffuse LGGs, our study of 151 tumors has discovered genetic alterations and potential therapeutic targets across the entire range of pediatric LGGs and LGGNTs.

Han SS, Son DJ, Yun H, et al.
Piperlongumine inhibits proliferation and survival of Burkitt lymphoma in vitro.
Leuk Res. 2013; 37(2):146-54 [PubMed] Free Access to Full Article Related Publications
Piperlongumine (PL), a pepper plant alkaloid from Piper longum, kills solid tumor cells in a highly selective, potent fashion. To evaluate whether PL may have similar effects on malignant blood cells, we determined the efficacy with which PL inhibits the B-lymphocyte derived neoplasm, Burkitt lymphoma (BL). Low micromolar concentrations of PL (IC(50) = 2.8 μM × 8.5 μM) curbed growth and survival of two EBV(+) BL cell lines (Daudi, Raji) and two EBV BL cell lines (Ramos, DG-75), but left normal peripheral blood B-lymphocytes unharmed. PL-dependent cytotoxicity was effected in part by reduced NF-κB and MYC activity, with the former being caused by inhibition of IκBα degradation, nuclear translocation of p65, and binding of NF-κB dimers to cognate DNA sequences in gene promoters. In 4 of 4 BL cell lines, the NF-κB/MYC-regulated cellular target genes, E2F1 and MYB, were down regulated, while the stress sensor gene, GADD45B, was up regulated. The EBV-encoded oncogene, LMP-1, was suppressed in Daudi and Raji cells. Considering that NF-κB, MYC and LMP-1 play a crucial role in the biology of many blood cancers including BL, our results provide a strong preclinical rationale for considering PL in new intervention approaches for patients with hematologic malignancies.

Requena C, Rubio L, Traves V, et al.
Fluorescence in situ hybridization for the differential diagnosis between Spitz naevus and spitzoid melanoma.
Histopathology. 2012; 61(5):899-909 [PubMed] Related Publications
AIMS: The differential diagnosis between Spitz naevus and spitzoid melanoma can be extremely difficult, or even impossible. In recent years, many attempts have been made to find specific histopathological or immunohistochemical markers, although none has proved successful. Because the prognosis and treatment of each are very different, it is important to distinguish between these entities. We evaluated the ability of the fluorescence in situ hybridization (FISH) assay-designed to detect the copy number of the RREB1 (6p25), MYB (6q23) and CCND1 (11q13) genes and of centromere 6 (Cep 6)-in order to distinguish between Spitz naevus and spitzoid melanoma.
METHODS AND RESULTS: We evaluated 12 spitzoid melanomas and six Spitz naevi from our records. The diagnosis of both conditions was based on previously described histopathological criteria. We obtained valuable results for FISH in eight spitzoid melanomas and five Spitz naevi. Chromosomal aberrations were detected in seven of the eight spitzoid melanomas (FISH-positive) and in none of the five Spitz naevi. The FISH-negative spitzoid melanoma was the least typical in its group.
CONCLUSIONS: FISH was able to distinguish between Spitz naevus and spitzoid melanoma, with a sensitivity of 87.5% and a specificity of 100%. Our findings suggest that FISH could prove a useful tool in the differential diagnosis between these entities.

Gysin S, Paquette J, McMahon M
Analysis of mRNA profiles after MEK1/2 inhibition in human pancreatic cancer cell lines reveals pathways involved in drug sensitivity.
Mol Cancer Res. 2012; 10(12):1607-19 [PubMed] Free Access to Full Article Related Publications
Mutationally activated KRAS, detected in approximately 90% of pancreatic ductal adenocarcinomas (PDA), has proven an intractable pharmacologic target to date. Consequently, efforts to treat KRAS-mutated cancers are focused on targeting RAS-regulated signaling pathways. In mouse models, expression of BRAF(V600E) combined with dominant-negative TP53 elicits PDA, and pharmacologic blockade of mitogen-activated protein/extracellular signal-regulated kinase (MEK) inhibits proliferation of human PDA-derived cell lines. To better understand the role of RAF→MEK→ERK signaling on PDA cell proliferation, we assessed the consequences of MEK inhibition on global patterns of mRNA expression and tumor cell proliferation in a panel of human PDA-derived cell lines. This analysis revealed that RAF→MEK→ERK signaling regulates mRNAs involved in cell-cycle control as well as regulators of the immune system. Linear regression analysis of relative drug sensitivity and mRNA expression revealed mRNAs and pathways correlating with relative drug sensitivity of the cell lines. Mice carrying orthotopically implanted pancreas tumors that were treated with MEK inhibitor displayed reduced tumor growth, concomitant with a reduction of cells in S phase. Furthermore, analysis of tumor mRNA expression revealed PDA cell lines to display similar baseline and MEK inhibitor mRNA expression profiles in vitro and in vivo. Among the proteins subject to downregulation following MEK inhibition, we identified c-MYC as a key driver of cell proliferation downstream of RAF→MEK→ERK signaling. Indeed, in some PDA cell lines, RNA interference-mediated silencing of c-MYC expression had antiproliferative effects similar to that of MEK inhibition, thereby highlighting the importance of c-MYC in key aspects of pancreatic cancer cell maintenance.

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