Gene Summary

Gene:MYBL2; MYB proto-oncogene like 2
Aliases: BMYB, B-MYB
Summary:The protein encoded by this gene, a member of the MYB family of transcription factor genes, is a nuclear protein involved in cell cycle progression. The encoded protein is phosphorylated by cyclin A/cyclin-dependent kinase 2 during the S-phase of the cell cycle and possesses both activator and repressor activities. It has been shown to activate the cell division cycle 2, cyclin D1, and insulin-like growth factor-binding protein 5 genes. Two transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Jul 2013]
Databases:VEGA, OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:myb-related protein B
Source:NCBIAccessed: 12 March, 2017


What does this gene/protein do?
Show (8)

Cancer Overview

MYBL2 isn't generally mutated in cancer. However, it is thought to be significant in cancer because of its role in regulating the expression of genes involved in cancer progression. In line with other studies Shi et al (2012) found polymorphisms in some of the genes that MYBL2 regulates (BIRC5, BCL2 and CLU) had prognostic significance in a large population-based study of 782 breast cancer patients.

Research Indicators

Publications Per Year (1992-2017)
Graph generated 12 March 2017 using data from PubMed using criteria.

Literature Analysis

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

  • Breast Cancer
  • Transcription Factors
  • Neuroblastoma
  • Neoplasm Proteins
  • Oligonucleotide Array Sequence Analysis
  • Biomarkers, Tumor
  • Gene Amplification
  • Messenger RNA
  • Chromosome 20
  • Nucleic Acid Hybridization
  • Cell Differentiation
  • Liver Cancer
  • Cell Cycle Proteins
  • Mutation
  • TNF
  • Promoter Regions
  • Down-Regulation
  • Cell Proliferation
  • Genetic Predisposition
  • Prostate Cancer
  • alpha-MSH
  • Adenocarcinoma
  • Cervical Cancer
  • MYBL2
  • Up-Regulation
  • FISH
  • Gene Expression Profiling
  • DNA-Binding Proteins
  • Disease Progression
  • Immunohistochemistry
  • Trans-Activators
  • Genes, myb
  • Nuclear Proteins
  • Proto-Oncogene Proteins
  • MicroRNAs
  • Proto-Oncogene Proteins c-myb
  • Signal Transduction
  • Transcription
  • Wnt Proteins
  • Cancer Gene Expression Regulation
Tag cloud generated 12 March, 2017 using data from PubMed, MeSH and CancerIndex

Specific Cancers (7)

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

Entity Topic PubMed Papers
Breast CancerMYBL2 and Breast Cancer View Publications23
Prostate CancerMYBL2 and Prostate Cancer View Publications5
Cervical CancerMYBL2 and Cervical Cancer View Publications2
-MYBL2 polymorphisms and cancer risk
Schwab et al (2008) found that 2 common polymorphic variants of MYBL2 (rs2070235 and rs11556379) were significantly underrepresented in 419 cancer patients compared to 230 controls. Thorner et al (2009) reported that MYBL2 germline variant (rs2070235, S427G) was associated with an increased risk of basal-like breast cancer.
NeuroblastomaMYBL2 and NeuroblastomaPrognostic
Raschella et al. (1999) reported that Expression of B-myb in neuroblastoma tumors is a poor prognostic factor independent from MYCN amplification.
Liver CancerMYBL2 and HCC

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

Latest Publications: MYBL2 (cancer-related)

Thomas C, Robinson C, Dessauvagie B, et al.
Expression of proliferation genes in formalin-fixed paraffin-embedded (FFPE) tissue from breast carcinomas. Feasibility and relevance for a routine histopathology laboratory.
J Clin Pathol. 2017; 70(1):25-32 [PubMed] Related Publications
AIM: Breast carcinoma proliferative activity, histological grade and commercial molecular tests are all important in prognostication and treatment. There is a particular need for improved, standardised techniques for subclassification of grade 2 breast cancers into low-risk and high-risk prognostic groups. In this study we investigated whether gene expression profiling of five proliferation genes was feasible using breast cancer tissue in a clinical setting and whether these profiles could enhance pathological assessment.
METHODS: Expression of five proliferation gene mRNAs; Ki-67, STK 15, CCNB1, CCND1 and MYBL2, was quantified in 27 breast carcinomas and compared with Ki-67 proliferation index (PI) and Nottingham mitotic score.
RESULTS: Expression of Ki-67, STK15 and MYBL2 mRNA showed moderate Spearman's correlation with Ki-67 PI (p<0.01), but CCND1 and CCNB1 showed weak, non-significant correlation. Individual gene expression did not associate with mitotic score but combined mRNA expression correlated with both Ki-67 PI (p=0.018) and mitotic score (p=0.03; 0.007).
CONCLUSIONS: This study confirms mRNA analysis in breast carcinoma formalin-fixed, paraffin-embedded samples is feasible and suggests gene expression profiling, using a small set of five proliferation genes, has potential in aiding histological grading or assessment of proliferative activity of breast cancers. To fully evaluate the clinical applicability of this approach, a larger cohort study with long-term follow-up data is required.

Mori K, Uchida T, Fukumura M, et al.
Linkage of E2F1 transcriptional network and cell proliferation with respiratory chain activity in breast cancer cells.
Cancer Sci. 2016; 107(7):963-71 [PubMed] Free Access to Full Article Related Publications
Mitochondria are multifunctional organelles; they have been implicated in various aspects of tumorigenesis. In this study, we investigated a novel role of the basal electron transport chain (ETC) activity in cell proliferation by inhibiting mitochondrial replication and transcription (mtR/T) using pharmacological and genetic interventions, which depleted mitochondrial DNA/RNA, thereby inducing ETC deficiency. Interestingly, mtR/T inhibition did not decrease ATP levels despite deficiency in ETC activity in different cell types, including MDA-MB-231 breast cancer cells, but it severely impeded cell cycle progression, specifically progression during G2 and/or M phases in the cancer cells. Under these conditions, the expression of a group of cell cycle regulators was downregulated without affecting the growth signaling pathway. Further analysis suggested that the transcriptional network organized by E2F1 was significantly affected because of the downregulation of E2F1 in response to ETC deficiency, which eventually resulted in the suppression of cell proliferation. Thus, in this study, the E2F1-mediated ETC-dependent mechanism has emerged as the regulatory mechanism of cell cycle progression. In addition to E2F1, FOXM1 and BMYB were also downregulated, which contributed specifically to the defects in G2 and/or M phase progression. Thus, ETC-deficient cancer cells lost their growing ability, including their tumorigenic potential in vivo. ETC deficiency abolished the production of reactive oxygen species (ROS) from the mitochondria and a mitochondria-targeted antioxidant mimicked the deficiency, thereby suggesting that ETC activity signaled through ROS production. In conclusion, this novel coupling between ETC activity and cell cycle progression may be an important mechanism for coordinating cell proliferation and metabolism.

Qin HD, Liao XY, Chen YB, et al.
Genomic Characterization of Esophageal Squamous Cell Carcinoma Reveals Critical Genes Underlying Tumorigenesis and Poor Prognosis.
Am J Hum Genet. 2016; 98(4):709-27 [PubMed] Free Access to Full Article Related Publications
The genetic mechanisms underlying the poor prognosis of esophageal squamous cell carcinoma (ESCC) are not well understood. Here, we report somatic mutations found in ESCC from sequencing 10 whole-genome and 57 whole-exome matched tumor-normal sample pairs. Among the identified genes, we characterized mutations in VANGL1 and showed that they accelerated cell growth in vitro. We also found that five other genes, including three coding genes (SHANK2, MYBL2, FADD) and two non-coding genes (miR-4707-5p, PCAT1), were involved in somatic copy-number alterations (SCNAs) or structural variants (SVs). A survival analysis based on the expression profiles of 321 individuals with ESCC indicated that these genes were significantly associated with poorer survival. Subsequently, we performed functional studies, which showed that miR-4707-5p and MYBL2 promoted proliferation and metastasis. Together, our results shed light on somatic mutations and genomic events that contribute to ESCC tumorigenesis and prognosis and might suggest therapeutic targets.

Ashaie MA, Chowdhury EH
Cadherins: The Superfamily Critically Involved in Breast Cancer.
Curr Pharm Des. 2016; 22(5):616-38 [PubMed] Related Publications
Breast cancer, one of the leading causes of mortality and morbidity among females, is regulated in part by diverse classes of adhesion molecules one of which is known as cadherins. Located at adherens junctions, the members of this superfamily are responsible for upholding proper cell-cell adhesion. Cadherins possess diverse structures and functions and any alteration in their structures or functions causes impeding of normal mammary cells development and maintenance, thus leading to breast malignancy. E-, N-, P-, VE-, Proto-, desmosomal and FAT cadherins have been found to regulate breast cancer in positive as well as negative fashion, whereby both Ecadherin (CDH1) and N-cadherin (CDH2) contribute significantly towards transitioning from epithelial state to mesenchymal state (EMT) and enacting the abnormal cells to invade and metastasize nearby and distant tissues. Aberration in gene expression of cadherins can be either due to somatic or epigenetic silencing or via transcriptional factors. Besides other cadherins, E-cadherin which serves as hallmark of EMT is associated with several regulatory factors such as Snail, Slug, Twist, Zeb, KLF4, NFI, TBX2, SIX, b-Myb, COX-2, Arf6, FOXA2, GATA3 and SMAR1, which modulate E-cadherin gene transcription to promote or represses tumor invasion and colonization. Signaling molecules such as Notch, TGF-β, estrogen receptors, EGF and Wnt initiate numerous signaling cascades via these vital factors of cell programming, controlling expression of E-cadherin at transcriptional (mRNA) and protein level. Thus, interactions of cadherins with their roles in tumor suppression and oncogenic transformation can be beneficial in providing valuable insights for breast cancer diagnosis and therapeutics development.

Fischer M, Quaas M, Nickel A, Engeland K
Indirect p53-dependent transcriptional repression of Survivin, CDC25C, and PLK1 genes requires the cyclin-dependent kinase inhibitor p21/CDKN1A and CDE/CHR promoter sites binding the DREAM complex.
Oncotarget. 2015; 6(39):41402-17 [PubMed] Free Access to Full Article Related Publications
The transcription factor p53 is central to cell cycle control by downregulation of cell cycle-promoting genes upon cell stress such as DNA damage. Survivin (BIRC5), CDC25C, and PLK1 encode important cell cycle regulators that are repressed following p53 activation. Here, we provide evidence that p53-dependent repression of these genes requires activation of p21 (CDKN1A, WAF1, CIP1). Chromatin immunoprecipitation (ChIP) data indicate that promoter binding of B-MYB switches to binding of E2F4 and p130 resulting in a replacement of the MMB (Myb-MuvB) by the DREAM complex. We demonstrate that this replacement depends on p21. Furthermore, transcriptional repression by p53 requires intact DREAM binding sites in the target promoters. The CDE and CHR cell cycle promoter elements are the sites for DREAM binding. These elements as well as the p53 response of Survivin, CDC25C, and PLK1 are evolutionarily conserved. No binding of p53 to these genes is detected by ChIP and mutation of proposed p53 binding sites does not alter the p53 response. Thus, a mechanism for direct p53-dependent transcriptional repression is not supported by the data. In contrast, repression by DREAM is consistent with most previous findings and unifies models based on p21-, E2F4-, p130-, and CDE/CHR-dependent repression by p53. In conclusion, the presented data suggest that the p53-p21-DREAM-CDE/CHR pathway regulates p53-dependent repression of Survivin, CDC25C, and PLK1.

Li R, Campos J, Iida J
A Gene Regulatory Program in Human Breast Cancer.
Genetics. 2015; 201(4):1341-8 [PubMed] Free Access to Full Article Related Publications
Molecular heterogeneity in human breast cancer has challenged diagnosis, prognosis, and clinical treatment. It is well known that molecular subtypes of breast tumors are associated with significant differences in prognosis and survival. Assuming that the differences are attributed to subtype-specific pathways, we then suspect that there might be gene regulatory mechanisms that modulate the behavior of the pathways and their interactions. In this study, we proposed an integrated methodology, including machine learning and information theory, to explore the mechanisms. Using existing data from three large cohorts of human breast cancer populations, we have identified an ensemble of 16 master regulator genes (or MR16) that can discriminate breast tumor samples into four major subtypes. Evidence from gene expression across the three cohorts has consistently indicated that the MR16 can be divided into two groups that demonstrate subtype-specific gene expression patterns. For example, group 1 MRs, including ESR1, FOXA1, and GATA3, are overexpressed in luminal A and luminal B subtypes, but lowly expressed in HER2-enriched and basal-like subtypes. In contrast, group 2 MRs, including FOXM1, EZH2, MYBL2, and ZNF695, display an opposite pattern. Furthermore, evidence from mutual information modeling has congruently indicated that the two groups of MRs either up- or down-regulate cancer driver-related genes in opposite directions. Furthermore, integration of somatic mutations with pathway changes leads to identification of canonical genomic alternations in a subtype-specific fashion. Taken together, these studies have implicated a gene regulatory program for breast tumor progression.

Duan L, Rai G, Roggero C, et al.
KDM4/JMJD2 Histone Demethylase Inhibitors Block Prostate Tumor Growth by Suppressing the Expression of AR and BMYB-Regulated Genes.
Chem Biol. 2015; 22(9):1185-96 [PubMed] Free Access to Full Article Related Publications
Histone lysine demethylase KDM4/JMJD2s are overexpressed in many human tumors including prostate cancer (PCa). KDM4s are co-activators of androgen receptor (AR) and are thus potential therapeutic targets. Yet to date few KDM4 inhibitors that have anti-prostate tumor activity in vivo have been developed. Here, we report the anti-tumor growth effect and molecular mechanisms of three novel KDM4 inhibitors (A1, I9, and B3). These inhibitors repressed the transcription of both AR and BMYB-regulated genes. Compound B3 is highly selective for a variety of cancer cell lines including PC3 cells that lack AR. B3 inhibited the in vivo growth of tumors derived from PC3 cells and ex vivo human PCa explants. We identified a novel mechanism by which KDM4B activates the transcription of Polo-like kinase 1 (PLK1). B3 blocked the binding of KDM4B to the PLK1 promoter. Our studies suggest a potential mechanism-based therapeutic strategy for PCa and tumors with elevated KDM4B/PLK1 expression.

Krakstad C, Tangen IL, Hoivik EA, et al.
ATAD2 overexpression links to enrichment of B-MYB-translational signatures and development of aggressive endometrial carcinoma.
Oncotarget. 2015; 6(29):28440-52 [PubMed] Free Access to Full Article Related Publications
We have explored the potential for clinical implementation of ATAD2 as a biomarker for aggressive endometrial cancer by investigating to what extent immunohistochemical (IHC) staining for ATAD2 is feasible, reflects clinical phenotype and molecular subgroups of endometrial carcinomas. Increased expression of the ATAD2 gene has been implicated in cancer development and progression in a number of tissues, but few studies have investigated ATAD2 expression using IHC. Here we show that high ATAD2 protein expression is significantly associated with established clinical-pathological variables for aggressive endometrial cancer, also in the subset of estrogen receptor α (ERα) positive tumors. Protein and mRNA expression of ATAD2 were highly correlated (P < 0.001), suggesting that IHC staining may represent a more clinically applicable measure of ATAD2 level in routinely collected formalin fixed paraffin embedded specimens. Gene expression alterations in samples with high ATAD2 expression revealed upregulation of several cancer-related genes (B-MYB, CDCs, E2Fs) and gene sets that previously have been linked to aggressive disease and potential for new targeting therapies. Our results support that IHC staining for ATAD2 may be a clinically applicable biomarker reflecting clinical phenotype and targetable alterations in endometrial carcinomas to be further explored in controlled clinical trials.

Johnson RH, Hu P, Fan C, Anders CK
Gene expression in "young adult type" breast cancer: a retrospective analysis.
Oncotarget. 2015; 6(15):13688-702 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Young women with breast cancer experience inferior outcome and commonly manifest aggressive biological subtypes. Data is controversial regarding biological differences between breast tumors in young (diagnosed at <40 years of age) versus older women. We hypothesize there may be age-related expression differences in key genes for proliferation, invasion and metastasis within and across breast cancer subtypes, and that these differences correlate with outcome.
METHODS: Using clinically-annotated gene expression data from 778 breast tumors from three public databases, we compared clinico-pathologic characteristics, mRNA expression of 17 selected genes, and outcome, as a function of age (< 40 years vs. ≥ 40 years).
RESULTS: 14 of 17 genes were differentially expressed in tumors of young vs. older women, 4 of which persisted after correction for subtype and grade (p ≤0.05). BUB1, KRT5, and MYCN were overexpressed and CXCL2 underexpressed in young women. In multivariate analysis, overexpression of cytokeratin genes predicted inferior DFS only for young women. Overexpression of ANGPTL4 strongly predicted inferior DFS in basal but not HER2-enriched tumors in young women. Overexpression of cytokeratin genes and MYBL2 and low SNAI1 expression correlated with inferior DFS in HER2-enriched tumors in younger women. Kaplan-Meier analysis within the basal and HER2-enriched subgroups showed that overexpression of cytokeratin genes was associated with inferior DFS for young, but not older women.
CONCLUSIONS: This preliminary study reveals age- and subtype-related differences in expression of key breast cancer genes for proliferation, invasion and metastasis, which correlate with prognostic differences in young women and suggest targeted therapies.

Wang X, Li M, Wang Z, et al.
Silencing of long noncoding RNA MALAT1 by miR-101 and miR-217 inhibits proliferation, migration, and invasion of esophageal squamous cell carcinoma cells.
J Biol Chem. 2015; 290(7):3925-35 [PubMed] Free Access to Full Article Related Publications
MALAT1, a highly conserved long noncoding RNA, is deregulated in several types of cancers. However, its role in esophageal squamous cell carcinoma (ESCC) and its posttranscriptional regulation remain poorly understood. In this study we provide first evidences that a posttranscriptional regulation mechanism of MALAT1 by miR-101 and miR-217 exists in ESCC cells. This posttranscriptional silencing of MALAT1 could significantly suppress the proliferation of ESCC cells through the arrest of G2/M cell cycle, which may be due to MALAT1-mediated up-regulation of p21 and p27 expression and the inhibition of B-MYB expression. Moreover, we also found the abilities of migration and invasion of ESCC cells were inhibited after overexpression of miR-101, miR-217, or MALAT1 siRNA. This might be attributed to the deregulation of downstream genes of MALAT1, such as MIA2, HNF4G, ROBO1, CCT4, and CTHRC1. A significant negative correlation exists between miR-101 or miR-217 and MALAT1 in 42 pairs of ESCC tissue samples and adjacent normal tissues. Mice xenograft data also support the tumor suppressor role of both miRNAs in ESCCs.

Tao D, Pan Y, Jiang G, et al.
B-Myb regulates snail expression to promote epithelial-to-mesenchymal transition and invasion of breast cancer cell.
Med Oncol. 2015; 32(1):412 [PubMed] Related Publications
Breast cancer is the leading cause of cancer death in women worldwide, which is closely related to metastasis. Recent studies argue that breast cancer cells that have undergone epithelial-to-mesenchymal transition (EMT) acquire aggressive malignant properties, but the molecular mechanisms underlying this transition are poorly understood. In this study, we found that siRNA-mediated attenuation of B-Myb expression restored E-cadherin expression and cell-cell junction formation in breast cancer cells, suppressing cell invasion, anchorage-independent growth, and tumor formation. In contrast, the forced B-Myb expression decreased the expression of the epithelial marker E-cadherin, but increased the mesenchymal markers in breast cancer cells. We found that B-Myb upregulated expression of the key EMT regulator snail and that it mediated EMT activation and cell invasion by B-Myb.

Gayral M, Lulka H, Hanoun N, et al.
Targeted oncolytic herpes simplex virus type 1 eradicates experimental pancreatic tumors.
Hum Gene Ther. 2015; 26(2):104-13 [PubMed] Free Access to Full Article Related Publications
As many other cancers, pancreatic ductal adenocarcinoma (PDAC) progression is associated with a series of hallmark changes for cancer cells to secure their own growth success. Yet, these very changes render cancer cells highly sensitive to viral infection. A promising strategy may rely on and exploit viral replication for tumor destruction, whereby infection of tumor cells by a replication-conditional virus may lead to cell destruction and simultaneous release of progeny particles that can spread and infect adjacent tumor cells, while sparing healthy tissues. In the present study, we used Myb34.5, a second-generation replication-conditional herpes simplex virus type 1 (HSV-1) mutant in which ICP6 gene expression is defective and expression of the HSV-1 γ134.5 gene is regulated by the cellular B-myb promoter. We found that B-myb is present in experimental PDAC and tumors, and is overexpressed in patients' tumors, as compared with normal adjacent pancreas. Myb34.5 replicates to high level in human PDAC cell lines and is associated with cell death by apoptosis. In experimental models of PDAC, mice receiving intratumoral Myb34.5 injections appeared healthy and tumor progression was inhibited, with evidence of tumor necrosis, hemorrhage, viral replication, and cancer cell death by apoptosis. Combining standard-of-care chemotherapy with Myb34.5 successfully led to a very impressive antitumoral effect that is rarely achieved in this experimental model, and resulted in a greater reduction in tumor growth than chemotherapy alone. These promising results warrant further evaluation in early phase clinical trial for patients diagnosed with PDAC for whom no effective treatment is available.

Rashid NN, Yusof R, Watson RJ
A B-myb--DREAM complex is not critical to regulate the G2/M genes in HPV-transformed cell lines.
Anticancer Res. 2014; 34(11):6557-63 [PubMed] Related Publications
BACKGROUND/AIM: It is well-established that HPV E7 proteins, encoded by human papillomavirus (HPV) genes, frequently associated with cervical cancers bind avidly to the retinoblastoma (RB) family of pocket proteins and disrupt their association with members of the E2F transcription factor family. Our previous study showed that the repressive p130-dimerization partner, RB-like, E2F and multi-vulval class (DREAM) complex was disrupted by HPV16 E7 proteins in order to maintain the viral replication in CaSki cells. However, we would like to address whether the activator B-myb-DREAM complex is critical in regulating the replication and mitosis phase since our previous study showed increased B-myb-DREAM expression in HPV-transformed cell lines when compared to control cells.
RESULTS: The association of B-myb with both LIN-54 and LIN-9 was equally decreased by depleting LIN-54 in CaSki cells. Flow cytometry analysis showed that LIN-54 depletion caused an increased proportion of G2/M cells in T98G, SiHa and CaSki cells. The mRNA levels of certain S/G2 genes such as cyclin B, aurora kinase A and Polo-like kinase 1 have demonstrated a marginal increased in CaSki-Lin-54-depleted cells when compared to SiHa- and T98G-Lin-54-depleted cells. We further confirmed this experiment by depleting the B-myb itself in CaSki cells and the results showed the same pattern of cell cycle and mRNA levels for S/G2 genes when compared to LIN-54- and LIN-9-depleted cells.
CONCLUSION: The B-myb-DREAM complex might not be vital for progression through mitosis in cells lacking a G1/S checkpoint and not as crucial as the p130-DREAM complex for the survival of the HPV virus.

Tao D, Pan Y, Lu H, et al.
B-myb is a gene implicated in cell cycle and proliferation of breast cancer.
Int J Clin Exp Pathol. 2014; 7(9):5819-27 [PubMed] Free Access to Full Article Related Publications
B-myb belongs to the myb family of transcription factors that include A-myb and c-myb. While A-myb and c-myb are tissue-specific, B-myb is broadly expressed in rapidly dividing cells of developing adult mammals. Results of our study showed that increased B-myb expression of was associated with the progression of breast cancer and that B-myb protein levels were significantly elevated in matched metastases. High B-myb levels also predict shorter overall survival of breast cancer patients. Moreover, B-myb stimulated transcription of target genes that promoted entry into the S and M-phases of the cell cycle, cell proliferation, migration and invasion in breast cancer. Taken together, our results strongly demonstrated that B-myb had a critical role in both cell cycle progression and tumorigenesis, and might serve as a novel potential target in the diagnosis and/or treatment of human breast cancer.

Yu Z, Kim J, He L, et al.
Functional analysis of miR-34c as a putative tumor suppressor in high-grade serous ovarian cancer.
Biol Reprod. 2014; 91(5):113 [PubMed] Related Publications
Altered microRNA expression patterns are implicated in the formation of many human diseases, including ovarian cancer. Our laboratory previously created Dicer(fl/fl)/Pten(fl/fl)/Amhr2(cre/+) mice, which developed high-grade serous carcinomas originating from mouse fallopian tubes, while neither Dicer(fl/fl)/Amhr2(cre/+) nor Pten(fl/fl)/Amhr2(cre/+) mice developed tumors. To explore miRNAs involved in the tumorigenesis in the double-knockout (DKO) mice, tumor cell lines were established from mouse primary tumors, and the most abundant miRNAs present in mouse normal fallopian tubes, let-7b and miR-34c, were expressed in these cell lines. We found that miR-34c had a more dramatic effect on inhibiting tumor cell viability than let-7b. The action of miR-34c induced tumor cell cycle arrest in G1 phase and apoptosis, and was accompanied with the regulation of key genes involved in cell proliferation and cell cycle G1/S transition. miR-34c suppressed the expression of Ezh2 and Mybl2, which may transcriptionally and functionally activate Cdkn1c. Furthermore, miR-34c levels are extremely low in human serous adenocarcinomas compared with human normal fallopian tubes. Expression of miR-34c in human ovarian cancer cells phenocopied its effects in DKO mouse tumor cells. However, miR-34b/c(-/-)/Pten(fl/fl)/Amhr2(cre/+) mice failed to develop high-grade serous carcinomas, implicating a combination of miRNAs in the tumorigenesis process. Thus, while miR-34c is a putative tumor suppressor in high-grade serous ovarian carcinoma with potential therapeutic advantages, screening of additional miRNAs for their effects alone and in combination with miR-34c is highly warranted to uncover miRNAs that synergize with miR-34c against cancer.

Kalinsky K, Lim EA, Andreopoulou E, et al.
Increased expression of tumor proliferation genes in Hispanic women with early-stage breast cancer.
Cancer Invest. 2014; 32(9):439-44 [PubMed] Free Access to Full Article Related Publications
Hispanic women have higher breast cancer mortality compared to non-Hispanic whites. We evaluated for Proliferation Axis Score differences, as determined by Oncotype Dx, in Hispanic and non-Hispanic white women with newly diagnosed breast cancer. We matched 219 women, based upon age, stage, and nodal status. Compared to non-Hispanic whites, Hispanic women with hormone-sensitive, HER2-negative early-stage breast cancer had a higher Proliferation Axis Score. No differences were seen in Recurrence Score, ER, PR, or HER2 by Oncotype DX. CCNB1 and AURKA were significantly higher in Hispanic women. These tumor differences may help explain breast cancer outcome differences between the two ethnicities.

Zha Y, Xia Y, Ding J, et al.
MEIS2 is essential for neuroblastoma cell survival and proliferation by transcriptional control of M-phase progression.
Cell Death Dis. 2014; 5:e1417 [PubMed] Free Access to Full Article Related Publications
MEIS2 has an important role in development and organogenesis, and is implicated in the pathogenesis of human cancer. The molecular basis of MEIS2 action in tumorigenesis is not clear. Here, we show that MEIS2 is highly expressed in human neuroblastoma cell lines and is required for neuroblastoma cell survival and proliferation. Depletion of MEIS2 in neuroblastoma cells leads to M-phase arrest and mitotic catastrophe, whereas ectopic expression of MEIS2 markedly enhances neuroblastoma cell proliferation, anchorage-independent growth, and tumorigenicity. Gene expression profiling reveals an essential role of MEIS2 in maintaining the expression of a large number of late cell-cycle genes, including those required for DNA replication, G2-M checkpoint control and M-phase progression. Importantly, we identify MEIS2 as a transcription activator of the MuvB-BMYB-FOXM1 complex that functions as a master regulator of cell-cycle gene expression. Further, we show that FOXM1 is a direct target gene of MEIS2 and is required for MEIS2 to upregulate mitotic genes. These findings link a developmentally important gene to the control of cell proliferation and suggest that high MEIS2 expression is a molecular mechanism for high expression of mitotic genes that is frequently observed in cancers of poor prognosis.

Shike M, Doane AS, Russo L, et al.
The effects of soy supplementation on gene expression in breast cancer: a randomized placebo-controlled study.
J Natl Cancer Inst. 2014; 106(9) [PubMed] Free Access to Full Article Related Publications
BACKGROUND: There are conflicting reports on the impact of soy on breast carcinogenesis. This study examines the effects of soy supplementation on breast cancer-related genes and pathways.
METHODS: Women (n = 140) with early-stage breast cancer were randomly assigned to soy protein supplementation (n = 70) or placebo (n = 70) for 7 to 30 days, from diagnosis until surgery. Adherence was determined by plasma isoflavones: genistein and daidzein. Gene expression changes were evaluated by NanoString in pre- and posttreatment tumor tissue. Genome-wide expression analysis was performed on posttreatment tissue. Proliferation (Ki67) and apoptosis (Cas3) were assessed by immunohistochemistry.
RESULTS: Plasma isoflavones rose in the soy group (two-sided Wilcoxon rank-sum test, P < .001) and did not change in the placebo group. In paired analysis of pre- and posttreatment samples, 21 genes (out of 202) showed altered expression (two-sided Student's t-test, P < .05). Several genes including FANCC and UGT2A1 revealed different magnitude and direction of expression changes between the two groups (two-sided Student's t-test, P < .05). A high-genistein signature consisting of 126 differentially expressed genes was identified from microarray analysis of tumors. This signature was characterized by overexpression (>2-fold) of cell cycle transcripts, including those that promote cell proliferation, such as FGFR2, E2F5, BUB1, CCNB2, MYBL2, CDK1, and CDC20 (P < .01). Soy intake did not result in statistically significant changes in Ki67 or Cas3.
CONCLUSIONS: Gene expression associated with soy intake and high plasma genistein defines a signature characterized by overexpression of FGFR2 and genes that drive cell cycle and proliferation pathways. These findings raise the concerns that in a subset of women soy could adversely affect gene expression in breast cancer.

Liu LY, Chang LY, Kuo WH, et al.
A supervised network analysis on gene expression profiles of breast tumors predicts a 41-gene prognostic signature of the transcription factor MYB across molecular subtypes.
Comput Math Methods Med. 2014; 2014:813067 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: MYB is predicted to be a favorable prognostic predictor in a breast cancer population. We proposed to find the inferred mechanism(s) relevant to the prognostic features of MYB via a supervised network analysis.
METHODS: Both coefficient of intrinsic dependence (CID) and Galton Pierson's correlation coefficient (GPCC) were combined and designated as CIDUGPCC. It is for the univariate network analysis. Multivariate CID is for the multivariate network analysis. Other analyses using bioinformatic tools and statistical methods are included.
RESULTS: ARNT2 is predicted to be the essential gene partner of MYB. We classified four prognostic relevant gene subpools in three breast cancer cohorts as feature types I-IV. Only the probes in feature type II are the potential prognostic feature of MYB. Moreover, we further validated 41 prognosis relevant probes to be the favorable prognostic signature. Surprisingly, two additional family members of MYB are elevated to promote poor prognosis when both levels of MYB and ARNT2 decline. Both MYBL1 and MYBL2 may partially decrease the tumor suppressive activities that are predicted to be up-regulated by MYB and ARNT2.
CONCLUSIONS: The major prognostic feature of MYB is predicted to be determined by the MYB subnetwork (41 probes) that is relevant across subtypes.

Diller M, Schüler S, Buchholz S, et al.
Effects of estriol on growth, gene expression and estrogen response element activation in human breast cancer cell lines.
Maturitas. 2014; 77(4):336-43 [PubMed] Related Publications
OBJECTIVE: Local application of estradiol (E2) to treat vulvovaginal atrophy in postmenopausal breast cancer patients receiving aromatase inhibitors is known to elevate serum estradiol levels and thereby might counteract breast cancer therapy. Thus, vaginal application of estriol (E3) has been recommended for these patients. However, it is unclear to what extent E3 stimulates breast cancer cell growth. In this study, we examined the effect of E3 on growth and gene expression of two human breast cancer cell lines.
METHODS: We used an established in vitro cell culture assay and compared the effect of E2 and E3 on growth of the estrogen receptor alpha-positive breast cancer cell lines MCF-7 and T-47D testing a wide range of hormone concentrations of 10(-12)-10(-7)M. E3 effects on gene expression were examined by means of reporter gene assays, RT-qPCR and Western blot analysis.
RESULTS: E3 acted as a potent estrogen and exerted a mitogenic effect on T-47D and MCF-7 cells at concentrations of 10(-9)M (288 pg/ml) and higher. With regard to activation of an estrogen response element (ERE) in breast cancer cells, effects of E3 were visible at 10(-10)M. The same concentrations of E3 activated expression of the estrogen-responsive gene PR and of the proliferation genes cyclin A2, cyclin B1, Ki-67, c-myc and b-myb, providing molecular mechanisms underlying the observed growth increase.
CONCLUSIONS: Like E2, low levels of E3 were able to trigger a robust estrogenic response in breast cancer cells. Thus, our data suggest caution regarding use of E3 by breast cancer survivors.

Yang ZH, Zheng R, Gao Y, et al.
Abnormal gene expression and gene fusion in lung adenocarcinoma with high-throughput RNA sequencing.
Cancer Gene Ther. 2014; 21(2):74-82 [PubMed] Related Publications
To explore the universal law of the abnormal gene expression and the structural variation of genes related to lung adenocarcinoma, the gene expression profile of GSE37765 were downloaded from Gene Expression Omnibus database. The differentially expressed genes (DEGs) were analyzed with t-test and NOISeq tool, and the core DEGs were screened out by combining with another RNA-seq data containing totally 77 pairs of samples in 77 patients with lung adenocarcinoma. Moreover, the functional annotation of the core DEGs was performed by using the Database for Annotation Visualization and Integrated Discovery following selection of oncogene and tumor suppressor by combining with tumor suppressor genes and Cancer Genes database, and motif-finding of core DEGs was performed with motif-finding algorithm Seqpos. We also used Tophat-fusion tool to further explore the fusion genes. In total, 850 downregulated DEGs and 206 upregulated DEGs were screened out in lung adenocarcinoma tissues. Next, we selected 543 core DEGs, including 401 downregulated and 142 upregulated genes, and vasculature development (P=1.89E-06) was significantly enriched among downregulated core genes, as well as mitosis (P=6.26E-04) enriched among upregulated core genes. On the basis of the cellular localization analysis of core genes, wnt-1-induced secreted protein 1 (WISP1) and receptor (G protein-coupled) activity modifying protein 1 (RAMP1) identified mainly located in extracellular region and extracellular space. We also screened one oncogene, v-myb avian myeloblastosis viral oncogene homolog-like 2 (MYBL2). Moreover, transcription factor GATA2 was mined by motif-finding analysis. Finally, four fusion genes belonged to the human leukocyte antigen (HLA) family. WISP1, RAMP1, MYBL2 and GATA2 could be potential targets of treatment for lung adenocarcinoma and the fusion of HLA family genes might have important roles in lung adenocarcinoma.

Parikh N, Hilsenbeck S, Creighton CJ, et al.
Effects of TP53 mutational status on gene expression patterns across 10 human cancer types.
J Pathol. 2014; 232(5):522-33 [PubMed] Free Access to Full Article Related Publications
Mutations in the TP53 tumour suppressor gene occur in half of all human cancers, indicating its critical importance in inhibiting cancer development. Despite extensive studies, the mechanisms by which mutant p53 enhances tumour progression remain only partially understood. Here, using data from the Cancer Genome Atlas (TCGA), genomic and transcriptomic analyses were performed on 2256 tumours from 10 human cancer types. We show that tumours with TP53 mutations have altered gene expression profiles compared to tumours retaining two wild-type TP53 alleles. Among 113 known p53-up-regulated target genes identified from cell culture assays, 10 were consistently up-regulated in at least eight of 10 cancer types that retain both copies of wild-type TP53. RPS27L, CDKN1A (p21(CIP1)) and ZMAT3 were significantly up-regulated in all 10 cancer types retaining wild-type TP53. Using this p53-based expression analysis as a discovery tool, we used cell-based assays to identify five novel p53 target genes from genes consistently up-regulated in wild-type p53 cancers. Global gene expression analyses revealed that cell cycle regulatory genes and transcription factors E2F1, MYBL2 and FOXM1 were disproportionately up-regulated in many TP53 mutant cancer types. Finally, > 93% of tumours with a TP53 mutation exhibited greatly reduced wild-type p53 messenger expression, due to loss of heterozygosity or copy neutral loss of heterozygosity, supporting the concept of p53 as a recessive tumour suppressor. The data indicate that tumours with wild-type TP53 retain some aspects of p53-mediated growth inhibitory signalling through activation of p53 target genes and suppression of cell cycle regulatory genes.

Warsow G, Struckmann S, Kerkhoff C, et al.
Differential network analysis applied to preoperative breast cancer chemotherapy response.
PLoS One. 2013; 8(12):e81784 [PubMed] Free Access to Full Article Related Publications
In silico approaches are increasingly considered to improve breast cancer treatment. One of these treatments, neoadjuvant TFAC chemotherapy, is used in cases where application of preoperative systemic therapy is indicated. Estimating response to treatment allows or improves clinical decision-making and this, in turn, may be based on a good understanding of the underlying molecular mechanisms. Ever increasing amounts of high throughput data become available for integration into functional networks. In this study, we applied our software tool ExprEssence to identify specific mechanisms relevant for TFAC therapy response, from a gene/protein interaction network. We contrasted the resulting active subnetwork to the subnetworks of two other such methods, OptDis and KeyPathwayMiner. We could show that the ExprEssence subnetwork is more related to the mechanistic functional principles of TFAC therapy than the subnetworks of the other two methods despite the simplicity of ExprEssence. We were able to validate our method by recovering known mechanisms and as an application example of our method, we identified a mechanism that may further explain the synergism between paclitaxel and doxorubicin in TFAC treatment: Paclitaxel may attenuate MELK gene expression, resulting in lower levels of its target MYBL2, already associated with doxorubicin synergism in hepatocellular carcinoma cell lines. We tested our hypothesis in three breast cancer cell lines, confirming it in part. In particular, the predicted effect on MYBL2 could be validated, and a synergistic effect of paclitaxel and doxorubicin could be demonstrated in the breast cancer cell lines SKBR3 and MCF-7.

Wu Z, Huang X, Huang X, et al.
The inhibitory role of Mir-29 in growth of breast cancer cells.
J Exp Clin Cancer Res. 2013; 32:98 [PubMed] Free Access to Full Article Related Publications
Mir-29 microRNA families are involved in regulation of various types of cancers. Although Mir-29 was shown to play an inhibitory role in tumorigenesis, the role of Mir-29 in breast cancer still remains obscure. In this study, we showed that Mir-29a is the dominant isoform in its family in mammary cells and expression of Mir-29a was down-regulated in different types of breast cancers. Furthermore, over-expression of Mir-29a resulted in significant slower growth of breast cancer cells and caused higher percentage of cells at G0/G1 phase. Consistent with this over-expression data, knockdown of Mir-29a in normal mammary cells lead to higher cell growth rate, and higher percentage of cells entering S phase. We further found that Mir-29a negatively regulated expression of B-Myb, which is a transcription factor associated with tumorigenesis. The protein levels of Cyclin A2 and D1 are consistent with the protein level of B-Myb. Taken together, our data suggests Mir-29a plays an important role in inhibiting growth of breast cancer cells and arresting cells at G0/G1 phase. Our data also suggests that Mir-29a may suppress tumor growth through down-regulating B-Myb.

Fuster O, Llop M, Dolz S, et al.
Adverse prognostic value of MYBL2 overexpression and association with microRNA-30 family in acute myeloid leukemia patients.
Leuk Res. 2013; 37(12):1690-6 [PubMed] Related Publications
The MYBL2 gene encodes a transcription factor implicated in cell proliferation and maturation whose amplification or overexpression has been associated with different human malignancies, suggesting that it could be implicated in tumorigenesis. We analyzed MYBL2 expression and its prognostic value in 291 patients with de novo acute myeloid leukemia (AML) and we also evaluated its association with microRNAs 29 and 30 families. MYBL2 expression in AML patients was increased relative to CD34+ cells. Moreover, MYBL2 overexpression was associated with lower expression of miR-30a (P=0.024), miR-30b (P=0.021) and miR-30c (P=0.009). Multivariate analysis showed that MYBL2 expression was an independent factor for disease-free survival (HR 3.0, 95% CI 1.5-6.0, P=0.002) and cumulative incidence of relapse (HR 2.6, 95% CI 1.2-5.6, P=0.015) in patients with an intermediate-risk karyotype. In conclusion, our data showed that MYBL2 expression analysis could be useful to define subgroups of patients with poor prognosis.

DeCaprio JA
Human papillomavirus type 16 E7 perturbs DREAM to promote cellular proliferation and mitotic gene expression.
Oncogene. 2014; 33(31):4036-8 [PubMed] Free Access to Full Article Related Publications
The study of the small DNA tumor viruses continues to provide valuable new insights into oncogenesis and fundamental biological processes. Although much has already been revealed about how the human papillomaviruses (HPVs) can transform cells and contribute to cervical and oropharyngeal cancer, there clearly is much more to learn. In this issue of Oncogene, Pang et al., doi:10.1038/onc.2013.426, demonstrate that the high-risk HPV16 E7 oncogene can promote cellular proliferation by interacting with the DREAM (DP, RB-like, E2F and MuvB) complex at two distinct phases of the cell cycle. Consistent with earlier work, HPV16 E7 can bind to the retinoblastoma tumor suppressor (RB) family member p130 (RBL2) protein and promote its proteasome-mediated destruction thereby disrupting the DREAM complex and can prevent exit from the cell cycle into quiescence. In addition, they demonstrate that HPV16 E7 can bind to MuvB core complex in association with BMYB and FOXM1 and activate gene expression during the G2 and M phase of the cell cycle. Thus, HPV16 E7 acts to prevent exit from the cell cycle entry and promotes mitotic proliferation and may account for the high levels of FOXM1 often observed in poor-risk cervical cancers.

Pang CL, Toh SY, He P, et al.
A functional interaction of E7 with B-Myb-MuvB complex promotes acute cooperative transcriptional activation of both S- and M-phase genes. (129 c).
Oncogene. 2014; 33(31):4039-49 [PubMed] Related Publications
High-risk human papillomaviruses are causative agents of cervical cancer. Viral protein E7 is required to establish and maintain the pro-oncogenic phenotype in infected cells, but the molecular mechanisms by which E7 promotes carcinogenesis are only partially understood. Our transcriptome analyses in primary human fibroblasts transduced with the viral protein revealed that E7 activates a group of mitotic genes via the activator B-Myb-MuvB complex. We show that E7 interacts with the B-Myb, FoxM1 and LIN9 components of this activator complex, leading to cooperative transcriptional activation of mitotic genes in primary cells and E7 recruitment to the corresponding promoters. E7 interaction with LIN9 and FoxM1 depended on the LXCXE motif, which is also required for pocket protein interaction and degradation. Using E7 mutants for the degradation of pocket proteins but intact for the LXCXE motif, we demonstrate that E7 functional interaction with the B-Myb-MuvB complex and pocket protein degradation are two discrete functions of the viral protein that cooperate to promote acute transcriptional activation of mitotic genes. Transcriptional level of E7 in patient's cervical lesions at different stages of progression was shown to correlate with those of B-Myb and FoxM1 as well as other mitotic gene transcripts, thereby linking E7 with cellular proliferation and progression in cervical cancer in vivo. E7 thus can directly activate the transcriptional levels of cell cycle genes independently of pocket protein stability.

Sadasivam S, DeCaprio JA
The DREAM complex: master coordinator of cell cycle-dependent gene expression.
Nat Rev Cancer. 2013; 13(8):585-95 [PubMed] Free Access to Full Article Related Publications
The dimerization partner, RB-like, E2F and multi-vulval class B (DREAM) complex provides a previously unsuspected unifying role in the cell cycle by directly linking p130, p107, E2F, BMYB and forkhead box protein M1. DREAM mediates gene repression during the G0 phase and coordinates periodic gene expression with peaks during the G1/S and G2/M phases. Perturbations in DREAM complex regulation shift the balance from quiescence towards proliferation and contribute to the increased mitotic gene expression levels that are frequently observed in cancers with a poor prognosis.

Frierson HF, Moskaluk CA
Mutation signature of adenoid cystic carcinoma: evidence for transcriptional and epigenetic reprogramming.
J Clin Invest. 2013; 123(7):2783-5 [PubMed] Free Access to Full Article Related Publications
Adenoid cystic carcinoma (ACC), a relatively rare malignancy usually of salivary gland origin, has a signature v-myb avian myeloblastosis viral oncogene homolog-nuclear factor I/B (MYB-NFIB) gene fusion that activates MYB transcriptional regulatory activity. A new study in this issue by Stephens et al. is a comprehensive genomic mutation profiling analysis of this neoplasm and documents a common theme of alteration in chromatin regulatory genes. Also, mutations in SPEN (split ends, homolog of Drosophila), which encodes an RNA-binding coregulatory protein, suggest that other changes in transcriptional regulation may involve the NOTCH, FGFR, or other signaling pathways in which SPEN participates. Since there is a low prevalence of mutations in common oncogenes and tumor-suppressor genes, it is likely that alterations primarily in specific transcriptional regulatory genes, augmented by changes in chromatin structure, drive the neoplastic process in ACC.

Stearns V, Jacobs LK, Fackler M, et al.
Biomarker modulation following short-term vorinostat in women with newly diagnosed primary breast cancer.
Clin Cancer Res. 2013; 19(14):4008-16 [PubMed] Free Access to Full Article Related Publications
PURPOSE: Agents that target the epigenome show activity in breast cancer models. In preclinical studies, the histone deacetylase inhibitor vorinostat induces cell-cycle arrest, apoptosis, and differentiation. We evaluated biomarker modulation in breast cancer tissues obtained from women with newly diagnosed invasive disease who received vorinostat and those who did not.
EXPERIMENTAL DESIGN: Tumor specimens were collected from 25 women who received up to 6 doses of oral vorinostat 300 mg twice daily and from 25 untreated controls in a nonrandomized study. Candidate gene expression was analyzed by reverse transcription PCR (RT-PCR) using the Oncotype DX 21-gene assay, and by immunohistochemistry for Ki-67 and cleaved caspase-3. Matched samples from treated women were analyzed for gene methylation by quantitative multiplex methylation-specific PCR (QM-MSP). Wilcoxon nonparametric tests were used to compare changes in quantitative gene expression levels pre- and post-vorinostat with changes in expression in untreated controls, and changes in gene methylation between pre- and post-vorinostat samples.
RESULTS: Vorinostat was well tolerated and there were no study-related delays in treatment. Compared with untreated controls, there were statistically significant decreases in the expression of proliferation-associated genes Ki-67 (P = 0.003), STK15 (P = 0.005), and Cyclin B1 (P = 0.03) following vorinostat, but not in other genes by the Oncotype DX assay, or in expression of Ki-67 or cleaved caspase-3 by immunohistochemistry. Changes in methylation were not observed.
CONCLUSIONS: Short-term vorinostat administration is associated with a significant decrease in expression of proliferation-associated genes in untreated breast cancers. This demonstration of biologic activity supports investigation of vorinostat in combination with other agents for the management of breast cancer.

Further References

Joaquin M, Watson RJ
Cell cycle regulation by the B-Myb transcription factor.
Cell Mol Life Sci. 2003; 60(11):2389-401 [PubMed] Related Publications
The expression of genes required for progression through the cell cycle is highly modulated through a regulatory axis containing the E2F transcription factor and retinoblastoma tumour suppressor protein families. One of the genes regulated through this mechanism encodes the B-Myb transcription factor, which has been shown to be critically required for early embryonal development in the mouse. Transcriptional activity of B-Myb is substantially enhanced in S phase through modification by cyclin A/cdk2, and the evidence points squarely to the major role being played by B-Myb during this phase of the cell cycle. We discuss in this review recent findings suggesting that B-Myb is a multifunctional protein that has, in addition to its transcriptional properties, the ability to interact directly with other regulators of the cell cycle.

Thorner AR, Hoadley KA, Parker JS, et al.
In vitro and in vivo analysis of B-Myb in basal-like breast cancer.
Oncogene. 2009; 28(5):742-51 [PubMed] Free Access to Full Article Related Publications
A defining feature of basal-like breast cancer, a breast cancer subtype with poor clinical prognosis, is the high expression of 'proliferation signature' genes. We identified B-Myb, a MYB family transcription factor that is often amplified and overexpressed in many tumor types, as being highly expressed in the proliferation signature. However, the roles of B-Myb in disease progression, and its mammary-specific transcriptional targets, are poorly understood. Here, we showed that B-Myb expression is a significant predictor of survival and pathological complete response to neoadjuvant chemotherapy in breast cancer patients. We also identified a significant association between the G/G genotype of a nonsynonymous B-Myb germline variant (rs2070235, S427G) and an increased risk of basal-like breast cancer [OR 2.0, 95% CI (1.1-3.8)]. In immortalized, human mammary epithelial cell lines, but not in basal-like tumor lines, cells ectopically expressing wild-type B-Myb or the S427G variant showed increased sensitivity to two DNA topoisomerase IIalpha inhibitors, but not to other chemotherapeutics. In addition, microarray analyses identified many G2/M genes as being induced in B-Myb overexpressing cells. These results confirm that B-Myb is involved in cell cycle control, and that its dysregulation may contribute to increased sensitivity to a specific class of chemotherapeutic agents. These data provide insight into the influence of B-Myb in human breast cancer, which is of potential clinical importance for determining disease risk and for guiding treatment.

Schwab R, Bussolari R, Corvetta D, et al.
Isolation and functional assessment of common, polymorphic variants of the B-MYB proto-oncogene associated with a reduced cancer risk.
Oncogene. 2008; 27(20):2929-33 [PubMed] Related Publications
The B-MYB proto-oncogene is a transcription factor belonging to the MYB family that is frequently overexpressed or amplified in different types of human malignancies. While it is suspected that B-MYB plays a role in human cancer, there is still no direct evidence of its causative role. Looking for mutations of the B-MYB gene in human cell lines and primary cancer samples, we frequently isolated two nonsynonymous B-MYB polymorphic variants (rs2070235 and rs11556379). Compared to the wild-type protein, the B-MYB isoforms display altered conformation, impaired regulation of target genes and decreased antiapoptotic activity, suggesting that they are hypomorphic variants of the major allele. Importantly, the B-MYB polymorphisms are common; rs2070235 and rs11556379 are found, depending on the ethnic background, in 10-50% of human subjects. We postulated that, if B-MYB activity is important for transformation, the presence of common, hypomorphic variants might modify cancer risk. Indeed, the B-MYB polymorphisms are underrepresented in 419 cancer patients compared to 230 controls (odds ratio 0.53; (95%) confidence interval 0.385-0.755; P=0.001). This data imply that a large fraction of the human population is carrier of B-MYB alleles that might be associated with a reduced risk of developing neoplastic disease.

Raschellà G, Cesi V, Amendola R, et al.
Expression of B-myb in neuroblastoma tumors is a poor prognostic factor independent from MYCN amplification.
Cancer Res. 1999; 59(14):3365-8 [PubMed] Related Publications
The transcription factors of the Myb family are expressed in several tissues and play an important role in cell proliferation, differentiation, and survival In this study, the expression of A-myb, B-myb, and c-myb was investigated in a group of 64 neuroblastomas at different dinical stages by a sensitive reverse transcription-PCR tchnique and correlated with patients' survival. All of the myb genes were frequently expressed in neuroblastoma tumors. Interestingly, the expression of B-myb, which was detected in 33 cases, was associated with an increased risk of death (P = 0.027 in a univariate analysis), whereas there was no correlation with A-myb and c-myb expression. In addition, in a multivariate Cox regression analysis that included myb gene expression, MYCN status, age at diagnosis, and tumor staging, MYCN amplification and B-myb expression were independently associated to an increased risk (P < 0.01 and P = 0.015, respectively). In overall survival curves obtained by stratifying the neuroblastoma cases on the basis of MYCN status and B-myb expression, the group of patients without MYCN amplification and positive for B-myb expression had worse survival probability than that without MYCN amplification and nonexpressing B-myb (P < 0.01). In summary, these findings provide the first demonstration that B-myb expression can be a useful prognostic marker in human neuroblastoma. Moreover, B-myb expression has a prognostic value complementary to MYCN amplification and can identify a group of high-risk patients that would not be predicted on the basis of the MYCN status only.

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