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  • 1
    Keywords: CANCER ; CELLS ; RISK ; TUMORS ; FAMILY ; BIOLOGY ; SUSCEPTIBILITY ; BREAST ; BREAST-CANCER ; STEM-CELLS ; MULTIPLE-MYELOMA ; MAMMARY-GLAND ; MUTATION CARRIERS ; ADHERENS JUNCTIONS ; EPITHELIUM ; MISSENSE MUTATIONS ; genetic variation ; MITOTIC SPINDLE ; BRCA1-DEPENDENT UBIQUITINATION ; CENTROSOMAL MICROTUBULE NUCLEATION ; PROGENITOR-CELL FATE
    Abstract: Differentiated mammary epithelium shows apicobasal polarity, and loss of tissue organization is an early hallmark of breast carcinogenesis. In BRCA1 mutation carriers, accumulation of stem and progenitor cells in normal breast tissue and increased risk of developing tumors of basal-like type suggest that BRCA1 regulates stem/progenitor cell proliferation and differentiation. However, the function of BRCA1 in this process and its link to carcinogenesis remain unknown. Here we depict a molecular mechanism involving BRCA1 and RHAMM that regulates apicobasal polarity and, when perturbed, may increase risk of breast cancer. Starting from complementary genetic analyses across families and populations, we identified common genetic variation at the low-penetrance susceptibility HMMR locus (encoding for RHAMM) that modifies breast cancer risk among BRCA1, but probably not BRCA2, mutation carriers: n = 7,584, weighted hazard ratio ((w)HR) = 1.09 (95% CI 1.02-1.16), p(trend) = 0.017; and n = 3,965, (w)HR = 1.04 (95% CI 0.94-1.16), p(trend) = 0.43; respectively. Subsequently, studies of MCF10A apicobasal polarization revealed a central role for BRCA1 and RHAMM, together with AURKA and TPX2, in essential reorganization of microtubules. Mechanistically, reorganization is facilitated by BRCA1 and impaired by AURKA, which is regulated by negative feedback involving RHAMM and TPX2. Taken together, our data provide fundamental insight into apicobasal polarization through BRCA1 function, which may explain the expanded cell subsets and characteristic tumor type accompanying BRCA1 mutation, while also linking this process to sporadic breast cancer through perturbation of HMMR/RHAMM.
    Type of Publication: Journal article published
    PubMed ID: 22110403
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  • 2
    Keywords: RECEPTOR ; ANGIOGENESIS ; CANCER ; CELLS ; EXPRESSION ; proliferation ; carcinoma ; CELL ; Germany ; THERAPY ; SUPPORT ; SYSTEM ; GENE ; GENE-EXPRESSION ; transcription ; TISSUE ; PATIENT ; ACTIVATION ; MECHANISM ; TRANSCRIPTION FACTOR ; TISSUES ; tumour ; BIOLOGY ; FREQUENCY ; FREQUENCIES ; ALPHA ; BREAST-CANCER ; ISOFORM ; TRANSGENIC MICE ; IN-SITU ; gene expression ; ASSAY ; resistance ; NUDE-MICE ; DISPLAY ; INVOLVEMENT ; PREVALENCE ; RECEPTORS ; FACTOR-I ; OXYGEN ; CELL CARCINOMA ; ONCOLOGY ; RE ; THERAPIES ; ASSAYS ; USA ; RENAL-CARCINOMA ; RARE ; HYPOXIA-INDUCIBLE FACTOR ; CONGENITAL POLYCYTHEMIA ; EPAS-1 ; erythrocytosis ; HIF-2 alpha ; HIPPEL-LINDAU GENE ; TUMOR-SUPPRESSOR PROTEIN ; VHL GENE
    Abstract: Signalling by erythropoietin (EPO) is increasingly recognised as a relevant mechanism in tumour biology, potentially leading to enhanced proliferation, angiogenesis and therapy resistance. Paraneoplastic polycythemia by cancerous overproduction of EPO is a rare event, but most frequently seen in patients with renal cell carcinoma (RCC). The majority of clear cell RCC displays a strong activation of the transcription factor regulating EPO, the Hypoxia-inducible Factor (HIF). Therefore, it is unclear why only a small minority of patients develop polycythemia. We studied 70 RCC for EPO gene and HIF alpha isoform expression. 34% of all RCC showed expression of EPO mRNA in RNase protection assays, which were almost exclusively of the clear cell type. Only I patient presented with polycythemia. In situ hybridisation revealed that expression of EPO was in the tumour cells. Expression of EPO mRNA was always associated with activation of HIF, which could involve HIF-1 alpha and/or HIF-2 alpha. The frequency of EPO gene expression in RCC is therefore much higher than the prevalence of polycythemia. Furthermore, activation of HIF appears necessary for EPO gene expression in RCC, but is clearly not the only determinant. Further to the reported expression of EPO receptors in tumour tissues, the finding of widespread expression of EPO in RCC supports the recent notion of an involvement of this system in paracrine or autocrine effects of tumour cells. (C) 2007 Wiley-Liss, Inc
    Type of Publication: Journal article published
    PubMed ID: 17640059
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  • 3
    Keywords: CANCER ; CELLS ; MODELS ; RISK ; GENE ; GENES ; PROTEIN ; PROTEINS ; DNA ; ASSOCIATION ; SUSCEPTIBILITY ; MUTATIONS ; DNA-DAMAGE ; CAENORHABDITIS-ELEGANS ; SUSCEPTIBILITY GENE ; HOMOLOGOUS RECOMBINATION ; ONCOLOGY ; PANCREATIC-CANCER ; C-ELEGANS ; GERM-CELLS ; FANCONI-ANEMIA ; ENGLAND ; BRCA2 MUTATION CARRIERS ; CHROMODOMAIN PROTEIN ; HELICASE BRIP1
    Abstract: Introduction: Proteins encoded by Fanconi anemia (FA) and/or breast cancer (BrCa) susceptibility genes cooperate in a common DNA damage repair signaling pathway. To gain deeper insight into this pathway and its influence on cancer risk, we searched for novel components through protein physical interaction screens. Methods: Protein physical interactions were screened using the yeast two-hybrid system. Co-affinity purifications and endogenous co-immunoprecipitation assays were performed to corroborate interactions. Biochemical and functional assays in human, mouse and Caenorhabditis elegans models were carried out to characterize pathway components. Thirteen FANCD2-monoubiquitinylation-positive FA cell lines excluded for genetic defects in the downstream pathway components and 300 familial BrCa patients negative for BRCA1/2 mutations were analyzed for genetic mutations. Common genetic variants were genotyped in 9,573 BRCA1/2 mutation carriers for associations with BrCa risk. Results: A previously identified co-purifying protein with PALB2 was identified, MRG15 (MORF4L1 gene). Results in human, mouse and C. elegans models delineate molecular and functional relationships with BRCA2, PALB2, RAD51 and RPA1 that suggest a role for MRG15 in the repair of DNA double-strand breaks. Mrg15-deficient murine embryonic fibroblasts showed moderate sensitivity to g-irradiation relative to controls and reduced formation of Rad51 nuclear foci. Examination of mutants of MRG15 and BRCA2 C. elegans orthologs revealed phenocopy by accumulation of RPA-1 (human RPA1) nuclear foci and aberrant chromosomal compactions in meiotic cells. However, no alterations or mutations were identified for MRG15/MORF4L1 in unclassified FA patients and BrCa familial cases. Finally, no significant associations between common MORF4L1 variants and BrCa risk for BRCA1 or BRCA2 mutation carriers were identified: rs7164529, P(trend) = 0.45 and 0.05, P(2df) = 0.51 and 0.14, respectively; and rs10519219, P(trend) = 0.92 and 0.72, P(2df) = 0.76 and 0.07, respectively. Conclusions: While the present study expands on the role of MRG15 in the control of genomic stability, weak associations cannot be ruled out for potential low-penetrance variants at MORF4L1 and BrCa risk among BRCA2 mutation carriers
    Type of Publication: Journal article published
    PubMed ID: 21466675
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