Expression In Breast Cancer Research Articles

Association between EGFR mutation and expression of BRCA1 and RAP80 in non-small cell lung cancer.

Association between the epithelial growth factor receptor (EGFR) mutation and the expression of breast cancer 1 (BRCA1) and receptor-associated protein 80 (RAP80) in non-small cell lung cancer (NSCLC) was studied. From September 2014 to September 2016, 51 patients with NSCLC who were hospitalized in Department of Thoracic Surgery in The Affiliated Jiangyin Hospital of Southeast University Medical College and underwent biopsy or operation were selected. The pathological changes of lung tissue were detected by hematoxylin and eosin histopathological staining. The fluorescent expression of BRCA1 and RAP80 protein in the two groups was determined by immunofluorescence staining. Reverse transcriptase polymerase chain reaction method and western blot analysis were used to detect BRCA1 and RAP80 mRNA and protein expression. Then the EGFR gene mutation was detected and analyzed. The results show that non-small cell lung cancer has an association with smoking. Compared with the control, the lung tissue structure of the NSCLC group was damaged. The protein fluorescence expression of BRCA1 and RAP80 in non-small cell lung cancer group was significantly increased. The expression of BRCA1 and RAP80 mRNA and protein in NSCLC group was significantly increased. The difference in expression of BRCA1 and RAP80 in the control and the non-small cell lung cancer group was statistically significant (P<0.05). EGFR gene mutations detected 14 of the 51 patients with genetic mutations. Non-small cell lung cancer and smoking have certain relevance, and BRCA1 and RAP80 expression in the development and progression of NSCLC has a close relationship. EGFR mutation in non-small cell lung cancer significantly related to the mutation of EGFR and BRCA1 and RAP80 gene expression plays an important role in the diagnosis and treatment of NSCLC.

Impact of Etoposide on BRCA1 Expression in Various Breast Cancer Cell Lines.

Breast cancer 1 (BRCA1), as a tumor suppressor, exerts an effective influence on protecting DNA integrity to suppress the development of breast cancer (BC). BRCA1 expression is induced in response to DNA-damaging agents such as etoposide. Germline BRCA1 gene mutations are associated with development of hereditary BC. However, besides BRCA-mutated BCs, some sporadic cancers may also exhibit a BRCA-like phenotype, displaying so-called ‘BRCAness’. This common phenotype may respond to similar therapeutic approaches as BRCA-mutated tumors and may thus have important implications for the clinical management of these cancers. In order to determine whether and how etoposide regulates the protein levels of BRCA1 in BC cells, we exposed a panel of five selected cell lines to etoposide, compared the results to untreated control cells, and then stained the cells with the specific, reliable, and reproducible MS110 antibody directed against phosphorylated Ser1423 BRCA1. By evaluating cytoplasmic BRCA1 protein levels, we were able to distinguish three aggressive BC subtypes with BRCAness characteristics. In addition, determination of early and late apoptosis helped to complete the analysis of BRCA1 functions in the DNA damage pathway of aggressive BC. In conclusion, our study suggested that high cytoplasmic BRCA1 protein levels could be considered as a potential predictive marker for response to chemotherapy in both sporadic and hereditary BC. Tumors with either BRCAness phenotype or germline BRCA1 mutation are both aggressive BCs associated with poor prognosis and could both be subjected to targeted therapies against BRCA1-mutated BC in future clinical management strategies.Electronic supplementary materialThe online version of this article (doi:10.1007/s40268-017-0208-6) contains supplementary material, which is available to authorized users.

Neonatal Nav1.5 protein expression in normal adult human tissues and breast cancer

Expression of the neonatal splice variant of the voltage-gated sodium channel α-subunit (VGSC) subtype Nav1.5 (nNav1.5), encoded by the gene SCN5A, was shown earlier to be upregulated in human breast cancer (BCa), both in vitro and in vivo. Channel activity promoted BCa invasion of Matrigel®in vitro and metastasis in vivo. Consequently, expression of nNav1.5 has been proposed as a functional biomarker of BCa cells with metastatic potential. Here, we have determined immunohistochemically both nNav1.5 and total VGSC (tVGSC) protein expression in a range of adult human tissues. Some VGSC protein was expressed in normal colon, small intestine, stomach, prostate, bladder and breast. As expected, high levels of VGSC protein were expressed in brain, skeletal muscle and cardiac muscle. On the other hand, nNav1.5 protein was not expressed in any of the normal tissues tested except breast where a low-level of protein was present. In comparison to normal breast, nNav1.5 protein expression in BCa was consistently widespread and occurred at a significantly higher level. We also questioned whether there was any relationship between the nNav1.5 protein expression and the estrogen receptor (ERα) status of BCa and obtained the following results. First, all cases lacking nNav1.5 were positive for ERα. Second, in all ERα-negative tissues, nNav1.5 protein was expressed in plasma membrane. Third, however, in ERα-positive cases, nNav1.5 protein expression was observed in both plasma membrane and cytoplasm. In conclusion, nNav1.5 protein has a restricted expression pattern among human tissues. High level expression occurs in BCa and associates with ERα status. These results further support the proposition that nNav1.5 is a novel biomarker of metastatic BCa.

BRCA1185delAG tumors may acquire therapy resistance through expression of RING-less BRCA1.

Heterozygous germline mutations in breast cancer 1 (BRCA1) strongly predispose women to breast cancer. BRCA1 plays an important role in DNA double-strand break (DSB) repair via homologous recombination (HR), which is important for tumor suppression. Although BRCA1-deficient cells are highly sensitive to treatment with DSB-inducing agents through their HR deficiency (HRD), BRCA1-associated tumors display heterogeneous responses to platinum drugs and poly(ADP-ribose) polymerase (PARP) inhibitors in clinical trials. It is unclear whether all pathogenic BRCA1 mutations have similar effects on the response to therapy. Here, we have investigated mammary tumorigenesis and therapy sensitivity in mice carrying the Brca1185stop and Brca15382stop alleles, which respectively mimic the 2 most common BRCA1 founder mutations, BRCA1185delAG and BRCA15382insC. Both the Brca1185stop and Brca15382stop mutations predisposed animals to mammary tumors, but Brca1185stop tumors responded markedly worse to HRD-targeted therapy than did Brca15382stop tumors. Mice expressing Brca1185stop mutations also developed therapy resistance more rapidly than did mice expressing Brca15382stop. We determined that both murine Brca1185stop tumors and human BRCA1185delAG breast cancer cells expressed a really interesting new gene domain-less (RING-less) BRCA1 protein that mediated resistance to HRD-targeted therapies. Together, these results suggest that expression of RING-less BRCA1 may serve as a marker to predict poor response to DSB-inducing therapy in human cancer patients.

Chemoresistance factors in non-small cell lung cancer

Lung cancer takes the leading position in cancer morbidity and mortality structure in the world and Ukraine. Advanced stages are diagnosed in more than 70% of lung cancer patients. Chemotherapy remains the main method of treatment for advanced lung cancer. Currently, the standard of chemotherapy in patients with III–IV stages of non-small cell lung cancer (NSCLC) is a combination of cisplatin/carboplatin with paclitaxel, etoposide, gemcitabine and vinorelbine. Although, the objective response rate after chemotherapy treatment is only about 20–50%. Low rates of chemotherapy efficacy are connected with chemoresistance of tumor to definite chemotherapeutic agents. Tumor chemoresistance is the result of different tumor intracellular mechanisms activity. Basing on current data we tried to analyze prognostic and predictive value of main chemoresistance factors in NSCLC. Conclusions . Nowadays we can certainly affirm that chemoresistance to cisplatin in NSCLC is due to increased expression of ERCC1 (Excision repair cross-complementation group 1 protein), BCRP; and resistance to taxanes is connected with elevated expression of β-tubuline III class; and tumoral chemoresistance to gemcitabine is due to high RRM1 (Ribinucleotide reductase M1) expression. High expression of BRCA1 (Breast Cancer 1) protein in tumors leads to increase of tumor cells resistance to cisplatin, but at the same time it increases the sensitivity to taxanes. Therefore, investigation of tumor chemoresistance plays an important role in algorithms’ creation for optimal chemotherapy schemes selection in patients with different stages of NSCLC in order to achieve the best tumor response to treatment and improve overall and disease-free survival. The information of main NSCLC chemoresistance factors, its prognostic and predictive value are presented in this overview.

Successful personalized chemotherapy for metastatic gastric cancer based on quantitative BRCA1 mRNA expression level: A case report.

Personalized chemotherapy is based on the specific genetic profile of individual patients and is replacing the traditional 'one size fits all' medicine. Breast cancer 1 (BRCA1) plays a central role in the chemotherapy-induced DNA damage response. It has been repeatedly demonstrated that BRCA1 mRNA levels were negatively associated with cisplatin sensitivity, but positively associated with docetaxel sensitivity in patients with gastric cancer in experimental and clinical studies. This feature leads to customized chemotherapy based on the BRCA1 mRNA expression level and results in a high efficacy of treatment. The present study describes the case of a 77-year-old patient with metastatic gastric cancer who was treated with personalized chemotherapy based on quantitative BRCA1 mRNA expression level. This study and the available literature data suggest that the expression level of BRCA1 mRNA is dynamic to BRCA1-based chemotherapy. More importantly, de novo assessment of BRCA1 status is a preferable option for ciscisplatin- or docetaxel-resistant patients, since the expression levels of BRCA1 mRNA in certain patients may alter significantly following treatment. Therefore, BRCA1 expression should be assessed for predicting differential chemosensitivity and tailoring chemotherapy in gastric cancer.

Analysis of ERCC1, BRCA1, RRM1 and TUBB3 as predictors of prognosis in patients with non-small cell lung cancer who received cisplatin-based adjuvant chemotherapy: A prospective study.

Although adjuvant platinum-based chemotherapy has been demonstrated to improve survival in patients with completely resected non-small cell lung cancer (NSCLC), individualized approaches to therapy are urgently required to improve the treatment efficacy and reduce unnecessary toxicity. It was hypothesized in the present study that the protein levels of excision repair cross-complementation group 1 (ERCC1), breast cancer 1 (BRCA1), ribonucleotide reductase M1 (RRM1) and class III β-tubulin (TUBB3) may influence the therapeutic effect of adjuvant cisplatin-based chemotherapy. The expression of ERCC1, BRCA1, RRM1 and TUBB3 in tissues obtained from 84 patients with NSCLC was analyzed in the present non-interventional study by immunohistochemistry prior to adjuvant chemotherapy. All patients received adjuvant cisplatin-based chemotherapy. The primary endpoint in the present study was disease free survival (DFS). Out of the 84 tumors, the expression of ERCC1, BRCA1, RRM1 and TUBB3 was identified in 46 (55%), 11 (13%), 73 (87%) and 76 (90%) tissues, respectively. A beneficial response to adjuvant cisplatin-based chemotherapy in DFS was associated with the absence of the expression of ERCC1 [hazard ratio (HR), 2.166; 95% confidence interval (CI), 1.049-4.474; P=0.037] and BRCA1 (HR, 2.419; 95% CI, 1.127-5.193; P=0.023), but not with the expression status of RRM1 (HR, 0.568; 95% CI, 0.234-1.379; P=0.212) or TUBB3 (HR, 1.874; 95% CI, 0.448-7.842; P=0.39). In addition, patients lacking the expression of ERCC1 and BRCA1 benefited more from adjuvant cisplatin-based chemotherapy compared with patients that expressed either ERCC1 or BRCA1 (HR, 3.102; 95% CI, 1.343-7.163; P=0.008). The expression of ERCC1 and BRCA1 was significantly associated with the DFS time in patients with NSCLC treated with adjuvant cisplatin-based chemotherapy, respectively. The combination of the ERCC1 and BRCA1 expression levels may be a promising prognostic prediction for adjuvant cisplatin-based chemotherapy.

Increased ID4 expression, accompanied by mutant p53 accumulation and loss of BRCA1/2 proteins in triple-negative breast cancer, adversely affects survival.

Breast cancer 1 (BRCA1) expression is down-regulated in a significant proportion of non-hereditary breast cancers, in the absence of any mutation. This phenomenon is more pronounced in oestrogen (ER)-negative tumours. Recent studies have suggested that inhibitor of DNA binding 4 (ID4), as well as p53, participate in the transcriptional regulation of BRCA1. Immunohistochemical expression of ID4, BRCA1, BRCA2 and p53 in 699 women with triple-negative breast cancer was investigated using tissue microarrays. The prognostic role of these biomarkers was also evaluated. Survival outcomes were estimated with the Kaplan-Meier method and compared between groups with log-rank statistics. Loss of BRCA1 and BRCA2 expression and overexpression of ID4 and p53 was observed in 75%, 90%, 95% and 66% of tumours, respectively. ID4 expression was increased in higher tumour grade (P < 0.001) and was associated significantly with basal-like subtype (P < 0.001), BRCA2 down-regulation (P = 0.037) and p53 accumulation (P < 0.001). Patients with strong ID4 expression displayed worse disease-free survival in both triple-negative breast cancers (P = 0.041) and basal-like triple-negative breast cancers (P = 0.026). There is frequent ID4 expression and concomitant loss of BRCA proteins in triple-negative breast cancer. We hypothesize that strong ID4 expression could be useful as a prognostic marker in triple-negative breast cancer, predicting early tumour recurrence.

Association of folate and other one-carbon related nutrients with hypermethylation status and expression of RARB, BRCA1, and RASSF1A genes in breast cancer patients.

Dietary methyl group donors could influence the hypermethylation status of certain putative genes. The present study explored the possible associations of dietary intake of one-carbon metabolism-related nutrients with promoter hypermethylation status and expression of retinoic acid receptor-beta (RARB), breast cancer-1 (BRCA1), and Ras association domain family-1, isoform A (RASSF1A) genes in Iranian women with breast cancer (BC). The hypermethylation status was investigated in 146 dissected BC tissue samples using methylation-specific PCR. The expression level was evaluated by real-time RT-PCR. Dietary nutrients were estimated using a validated 136-item food frequency questionnaire. Expression levels of the genes were associated with the unmethylated status of related promoters (p < 0.05). The crude dietary folate and adjusted cobalamin intakes were inversely associated with methylated RARB and BRCA1. Low intake of residual folate and cobalamin was correlated with the methylated status of RARB for subjects at <48 years of age, and folate alone was linked to BRCA1 at >48 years of age. High dietary intake of riboflavin and pyridoxine was the only determinant of the methylated promoter of RARB at odds ratios (ORs) of 4.15 (95 % confidence interval (CI) 1.28-13.50) and 2.53 (95 % CI 1.14-3.83) in multivariate models, respectively. One-carbon nutrients most often correlated inversely with the methylation-influenced expression of RARB. Although high folate intake increased the chance of unmethylation-dependent overexpression of BRCA1 3-fold, cobalamin and methionine were inversely linked to methylation-mediated expression. Nutritional epigenomics less actively influenced RASSF1A. These findings provide new insights into and a basic understanding of the selective contributions of individual B vitamins on hypermethylation and methylation-related expression of RARB and BRCA1 in BC. Hypermethylation at promoters of RARB, BRCA1, and RASSF1A is associated with reduced transcript levels of the respective gene in primary breast cancer tissue samples. Dietary folate and cobalamin intake is inversely associated with methylated RARB and BRCA1. High dietary intake of riboflavin and pyridoxine is associated with increased methylation in the RARB promoter. There is evidence for the age-dependent effects of nutrient intake on promoter methylation status. Bioavailability to the pool of nutrients might determine selectivity.

BRCA1 regulation of epidermal growth factor receptor (EGFR) expression in human breast cancer cells involves microRNA-146a and is critical for its tumor suppressor function.

Breast cancer 1 (BRCA1)-associated breast cancers are mostly basal-like high-grade ductal carcinomas that frequently overexpress epidermal growth factor receptor (EGFR). Aberrant EGFR expression is correlated with disease progression, resistance to radiation and chemotherapy, and poor clinical prognosis. Although BRCA1 is involved in multiple cellular processes, its functional role in EGFR regulation remains enigmatic. Here, we report a previously unrecognized posttranscriptional mechanism by which BRCA1 regulates EGFR expression through the induction of miR-146a. We demonstrate that EGFR expression correlates negatively with BRCA1, whereas miR-146a levels increase with BRCA1. We show that BRCA1 binds to MIR146A promoter and activates transcription, which in turn attenuates EGFR expression. Knockdown of miR-146a in BRCA1-overexpressing cells negated this effect and suppressed its ability to inhibit proliferation and transformation. In archived triple-negative breast cancer samples, we show a strong positive correlation between BRCA1 and miR-146a expression. We also show that low expression of miR-146a strongly predicts positive lymph node status and is associated with distinctively poor overall survival of patients. Together, these observations provide an insight into a novel BRCA1miR-146aEGFR paradigm by which BRCA1 carries out an aspect of tumor suppressor function that is potentially amenable to therapeutic intervention.

MiR-218 regulates cisplatin chemosensitivity in breast cancer by targeting BRCA1.

Cisplatin resistance presents a major challenge in the successful treatment of breast cancer, and its mechanism has not been documented well. In this study, to determine the relationship between chemotherapy resistance and microRNA (miRNA) expression during the development of cisplatin resistance in breast cancer, we used microRNA microarrays analysis successfully identified 19 miRNAs that were either overexpressed or underexpressed (8 upregulated and 11 downregulated) in the MCF-7 cell line and its cisplatin-resistant variant MCF-7/DDP. Among them, the miR-218 was most downregulated in cisplatin-resistant cell lines and identified that breast cancer 1 (BRCA1) was the cellular targets of miR-218. In vivo assay also demonstrated that restoring miR-218 expression in MCF-7/DDP cell line could sensitize cells against cisplatin, thereby increasing cisplatin-mediated tumor cell apoptosis and reducing DNA repair. Kaplan-Meier survival analysis indicated that patients with breast cancer display high levels of miR-218 and low levels of BRCA1 expression; these patients may gain the greatest benefits in terms of increased survival when treated with cisplatin. All of these results indicated that miR-218 has a significant function in the development of cisplatin resistance in breast cancer. Restoring miR-218 expression may constitute a novel therapeutic approach by which to increase cisplatin sensitivity in breast cancer.

160P - Cd163 Expression in Cancer Cells is Caused By Cell Fusion and Cannot Be Explained By Paracrine Cellular Interaction- an in Vitro Study with Mcf-7 Cells and Human M2-Macrophages

ABSTRACT Aim: It is suggested that fusion between tumor associated macrophages and cancer cells might contribute to cancer progression, even though the extent of this phenomenon in cancer remains to be explored. Cell fusion is a normal biological process that occurs in placenta and tissue regeneration. In cancer, it is proposed to result in hybrids with increased metastatic ability and phenotypic properties from both maternal cells. The macrophage-specific antigen CD163 is expressed by tumor cells in breast cancer (BRC), an observation that is not clearly defined but proposed to be due to cell fusion. In this study we investigate cellular mechanisms that might explain CD163 expression in BRC. Methods: Monocytes (harvested from male blood donors, differentiated to M2 macrophages) were co-cultured with GFP expressing MCF-7 BRC cell line to generate MCF-7/macrophage hybrids by spontaneous cell fusion. MCF-7 cells were also cultured with M2-macrophages in transwell chamber system (TCS) allowing paracrine interaction but physical separation to prevent cell fusion. The hybrids were isolated by fluorescence-activated cell sorting based on GFP and CD163 co-expression. Hybrids were confirmed by immunofluorescence microscopy, flow cytometry, and XY-STR analysis. CD163 expression in BRC from 127 patients was examined in relation to clinical data. Results: The hybrids showed phenotypic and genotypic traits from both maternal cells; a result which could not be achieved by co-culture of these cells in TCS, indicating that CD163 expression in MCF-7 cells cannot be induced by paracrine cellular interaction. The frequency of in vitro produced hybrids was 2–5% of the total amount of macrophages. CD163 was expressed in 48% of BRC tumors and associated with shorter survival. CD163 positive cancer cells in tumor sections grew in clonal collection and a cutoff point >25% of positive cancer cells was significantly correlated to disease free and overall survival. Conclusions: Macrophage traits in BRC cells are caused by cancer cell-macrophage fusion and cannot be explained by paracrine interaction. Cell fusion might contribute to heterogeneity and clonality in BRC. These data provide new insights into the role of cell fusion in breast cancer and contributes to the development of clinical markers to identify cell fusion. Disclosure: All authors have declared no conflicts of interest.

ERCC1 and BRCA1 mRNA expressions are associated with clinical outcome of non-small cell lung cancer treated with platinum-based chemotherapy

We conducted a perspective study to investigate whether the expression of excision repair cross-complementing 1 (ERCC1), xeroderma pigmentosum group G (XPG), breast cancer 1 (BRCA1), and ribonucleotide reductase M1 (RRM1) is correlated with clinical outcome of non-small cell lung cancer (NSCLC). Patients with histologically confirmed inoperable stages IIIB and IV NSCLC were collected and followed up until January 2012. Relative cDNA quantification for ERCC1, XPG, BRCA1, and RRM1 was performed using a fluorescence-based, real-time detection method. Cox regression analysis indicated that a high level of ERCC1 was associated with shorter overall survival (OS) and progression-free survival (PFS) times when compared with low expression, with adjusted hazard ratios (HRs) (95% confidence interval (CI)) of 2.25 (1.18-4.39) and 2.63 (1.33-5.25), respectively. High expression of BRCA1 was correlated with shorter OS and PFS times when compared with low expression, and the adjusted HRs (95% CI) were 3.29 (1.72-6.39) and 5.94 (2.80-13.06), respectively. Moreover, we found a significant correlation between BRCA1 expression and age (χ(2) = 4.14, P = 0.04) and stage (χ(2) = 5.26, P = 0.02). Our results suggest that ERCC1 and BRCA1 mRNA expressions are associated with PFS and OS in advanced NSCLC patients treated with platinum-based chemotherapy.

EZH2 participates in malignant biological behavior of epithelial ovarian cancer through regulating the expression of BRCA1

Aberrant overexpression of the enhancer of zeste homolog 2 (EZH2), a histone methyltransferase inhibiting targets expression via epigenetic mechanisms, is associated with an invasive phenotype and drug resistance in ovarian cancer. Breast cancer 1 (BRCA1) gene is a well-recognized tumor suppressor, whose downregulation plays a key role in the development of ovarian cancer. In the present study, we found depletion of EZH2 increased BRCA1 protein expression and promoted its nuclear translocation, but decreased BRCA1 mRNA expression. Treatment with the Akt-1 activator insulin-like growth factor-1 (IGF-1) prevented EZH2-induced BRCA1 nuclear/cytoplasmic shuttling. Loss of BRCA1 partially rescued the effects of EZH2 downregulation on proliferation, G2/M transition, and migration in ovarian cancer cells. However, in a cisplatin-resistant sub-line of A2780 (A2780/DDP), both EZH2 and BRCA1 were overexpressed compared with parental A2780 cells and depletion of EZH2 reduced BRCA1 expression at both mRNA and protein levels. Downregulation of EZH2 or BRCA1 sensitized A2780/DDP cells to cisplatin, whereas simultaneous inhibition of them only resulted in modest resensitization instead of showing any synergistic effect because EZH2 expression was reactivated when BRCA1 expression was very low. Accordingly, our results suggest the expression of BRCA1 is modulated by EZH2 in epithelial ovarian cancer and BRCA1 is required for the effects of EZH2 downregulation on biological behaviors of tumor cells.

Gestational exposure to the AhR agonist 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin induces BRCA‐1 promoter hypermethylation and reduces BRCA‐1 expression in mammary tissue of rat offspring: Preventive effects of resveratrol

Studies with murine models suggest that maternal exposure to aromatic hydrocarbon receptor (AhR) agonists may impair mammary gland differentiation and increase the susceptibility to mammary carcinogenesis in offspring. However, the molecular mechanisms responsible for these perturbations remain largely unknown. Previously, we reported that the AhR agonists 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) induced CpG methylation of the breast cancer-1 (BRCA-1) gene and reduced BRCA-1 expression in breast cancer cell lines. Based on the information both the human and rat BRCA-1 genes harbor xenobiotic responsive elements (XRE = 5'-GCGTG-3'), which are binding targets for the AhR, we extended our studies to the analysis of offspring of pregnant Sprague-Dawley rats treated during gestation with TCDD alone or in combination with the dietary AhR antagonist resveratrol (Res). We report that the in utero exposure to TCDD increased the number of terminal end buds (TEB) and reduced BRCA-1 expression in mammary tissue of offspring. The treatment with TCDD induced occupancy of the BRCA-1 promoter by DNA methyltransferase-1 (DNMT-1), CpG methylation of the BRCA-1 promoter, and expression of cyclin D1 and cyclin-dependent kinase-4 (CDK4). These changes were partially overridden by pre-exposure to Res, which stimulated the expression of the AhR repressor (AhRR) and its recruitment to the BRCA-1 gene. These findings point to maternal exposure to AhR agonists as a risk factor for breast cancer in offspring through epigenetic inhibition of BRCA-1 expression, whereas dietary antagonists of the AhR may exert protective effects.

Expression of DNA-PKcs and BRCA1 as prognostic indicators in nasopharyngeal carcinoma following intensity-modulated radiation therapy

The mechanisms of radiation-induced effects in cancer mainly involve double-strand breaks (DSBs) which are important in maintaining the stability of genes. The DNA repair genes breast cancer 1 (BRCA1) and DNA-dependent protein kinase catalytic subunit (DNA-PKcs) are capable of maintaining genetic stability through two distinct and complementary repair mechanisms for DNA DSBs, known as repair-homologous recombination (HR) and non-homologous end joining (NHEJ). DNA-PKcs is a member of the phosphatidylinositol 3-kinase (PI3K) family. The PI3K/AKT cell signaling pathway is implicated in cell migration and invasion. The BRCA1 protein is implicated in multiple complex cellular processes that are related to chromosome sensitivity to mutagens. To determine the protein expression and clinical implications of DNA-PKcs and BRCA1 in nasopharyngeal carcinoma (NPC) and cancer progression, we evaluated its expression status by immunohistochemistry in 87 patients who received intensity-modulated radiation therapy (IMRT). In NPC, negative expression of DNA-PKcs was detected in 35 of the 87 (40.2%) cancer types and was significantly associated with poor patient survival (P<0.05). The overexpression of DNA-PKcs and BRCA1 also led to significantly improved distant metastasis-free survival compared with patients who did not overexpress both genes, although the expression level of BRCA1 and distant metastasis-free survival were not closely correlated. In addition, multivariate analysis indicated that DNA-PKcs status is a predictive marker of distant metastasis-free survival. In conclusion, lower expression of DNA-PKcs may be correlated with higher distant metastasis in patients with NPC. DNA-PKcs may be a predictive marker of distant metastasis after IMRT, independent of the classical prognostic marker. BRCA1 may additionally exert a synergistic effect to predict distant metastasis-free survival.

Abstract 133: MiR-182 overexpression and ovarian high grade serous carcinoma

Abstract OBJECTIVES: BRCA1/BRCA2 mutations are hallmarks high grade papillary serous carcinoma (H-PSC). This correlation is due to the fact that approximately 40-50% of H-PSC have altered expression of BRCA1/BRCA2 (including germline and somatic mutations and epigenetic modifications). Furthermore, women with germline mutations of BRCA1/2 have a 30%-70% chance of developing H-PSC by the age of 70. If inactivation of BRCA1/2 is critical in the early tumorigenesis of H-PSC, there must be other mechanisms whereby BRCA1/2 is downregulated in the remaining 50% of H-PSC. Recent findings of miR-182-mediated repression of BRCA1 expression and significant overexpression of miR-182 in H-PSC suggest that miR-182 may play an important role in the tumorigenesis of H-PSC through its negative regulation of BRCA1. DESIGNS: To explore the role of miR-182 through the negative regulation of BRCA1 in the early stages of H-PSC tumorigenesis, we conducted in vitro molecular and cellular analyses of miR-182 in human fallopian tube secretory (FTSE) and ovarian surface epithelia (OSE) cell lines. We 1) established stable cell lines with stable miR-182 overexpression; 2) examined the oncogenic properties of miR-182 by anchorage-independent growth, cell proliferation and invasion in vitro; 3) investigated DNA damage response in cells with miR-182 expression after ionizing radiation (IR); 4) examined and characterized several predicted target genes of miR-182, including BRCA1, HMGA2 and MTSS1; 5) studied tumor growth and metastasis in vivo (in nude mice) with and without miR-182 overexpression. RESULTS: 1) Introducing miR-182 overexpression in normal immortalized cell lines (both FTSE and OSE) resulted in tumor transformation and significantly enhanced cell invasion in vitro. 2) FTSE and OSE cell lines with miR-182 overexpression had impaired repair of DNA double-strand breaks when treated with low doses of IR. 3) We further demonstrated that the oncogenic properties of miR-182 in ovarian cancer were mediated by its negative regulation of breast cancer 1 (BRCA1) and metastasis suppressor 1 (MTSS1) expression and its positive regulation of oncogene high-mobility group AT-hook 2 (HMGA2). Knockdown of miR-182 expression in ovarian cancer cell lines (SKOV3, and HEY) could therefore partially restore BRCA1 and MTSS1 expression and reduce aggressive tumor growth in vitro. Ovarian cancer cell line SKOV3 with miR-182 overexpression enhances lung metastasis in vivo. CONCLUSION: MiR-182 confers a powerful oncogenic potential in normal and malignant ovarian/fallopian tube cell lines through its negative regulation of several critical target genes in H-PSC, including BRCA1, MTSS1 and HMGA2. Therefore, MiR-182 likely plays a significant role in the early tumorigenesis of H-PSC. Our findings provide a novel target and a new potential therapeutic modality in treating H-PSC. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 133. doi:1538-7445.AM2012-133

Breast cancer 1 (BRCA1) protein expression as a prognostic marker in sporadic epithelial ovarian carcinoma: an NCIC CTG OV.16 correlative study

BackgroundBreast cancer 1 (BRCA1) protein inactivation in sporadic ovarian carcinoma (OC) is common and low BRCA1 expression is linked with platinum sensitivity. The clinical validation of BRCA1 as a prognostic marker in OC remains unresolved. Patients and methodsIn 251 patient samples from the NCIC CTG clinical trial, OV.16, BRCA1 protein expression was determined by immunohistochemistry. ResultsFor all patients, when BRCA1 score was analyzed as a continuous variable, there was no significant correlation between BRCA1 protein expression and progression-free survival (PFS) [adjusted hazard ratio (HR) = 1.15 (0.96–1.37), P = 0.12] or response rate [HR = 0.89 (0.70–1.12), P = 0.32]. In the 116 patients with minimal residual disease (RD), higher BRCA1 expression correlated significantly with worse PFS [HR = 1.40 (1.04–1.89), P = 0.03]. Subgroup analysis divided patients with minimal RD into low (BRCA1 ≤2.5) and high (BRCA1 >2.5) expression groups. Patients with low BRCA1 expression had a more favorable outcome [median PFS was 24.7 and 16.6 months in patients with low and high BRCA1, respectively; HR = 0.56 (0.35–0.89), P = 0.01]. ConclusionsThis study suggests that BRCA1 protein is a prognostic marker in sporadic OC patients with minimal RD. Further research is needed to evaluate BRCA1 as a predictive biomarker and to target BRCA1 expression to enhance chemotherapeutic sensitivity.

ERCC5/XPG, ERCC1, and BRCA1 gene status and clinical benefit of trabectedin in patients with soft tissue sarcoma

The objective of this study was to determine whether specific single nucleotide polymorphisms (SNPs) from nucleotide excision repair (NER) and homologous recombination (HR) DNA repair pathways are associated with sensitivity to trabectedin in patients with soft tissue sarcoma (STS). The authors analyzed excision repair cross-complementation group 5/xeroderma pigmentosum group G (ERCC5/XPG) (NER), excision repair cross-complementation group 1 (ERCC1) (NER), and breast cancer 1 (BRCA1) (HR) SNPs and messenger RNA expression levels in tumor specimens from 113 patients with advanced STS who were enrolled in previously published phase 2 trials or in a compassionate-use program. The 6-month progression-free rate (PFR), progression-free survival (PFS), and overall survival (OS) were analyzed according to ERCC5, ERCC1, and BRCA1 status using log-rank tests. High expression of the common allele (aspartic acid at codon 1104) of ERCC5, high expression of ERCC1, and BRCA1 haplotype were associated significantly with improved PFR, PFS, and OS. The ERCC1 thymine-to-cytosine (T→C) SNP at codon 19007 and BRCA1 expression were not associated with outcome. On univariate analysis, tumor histology, favorable NER status (high expression of common ERCC5 and/or high ERCC1 expression status), and favorable BRCA1 haplotype (at least 1 triple-adenine plus guanine [AAAG] allele) were the sole variables associated significantly with PFS and OS. In the current study, ERCC5, ERCC1, and BRCA1 status represented a potential DNA repair signature that could be used for the prediction of clinical response to trabectedin in patients with STS.

The effect of the histone deacetylase inhibitor M344 on BRCA1 expression in breast and ovarian cancer cells

BackgroundThe inhibition of Breast Cancer 1 (BRCA1) expression sensitizes breast and ovarian cancer cells to platinum chemotherapy. However, therapeutically relevant agents that target BRCA1 expression have not been identified. Our recent report suggested the potential of the histone deacetylase (HDAC) inhibitor, M344, to inhibit BRCA1 expression. In this study, we further evaluated the effect of M344 on BRCA1 mRNA and protein expression, as well as its effect on cisplatin-induced cytotoxicity in various breast (MCF7, T-47D and HCC1937) and ovarian (A2780s, A2780cp and OVCAR-4) cancer cell lines.ResultsWith the addition of M344, the platinum-sensitive breast and ovarian cancer cell lines that displayed relatively high BRCA1 protein levels demonstrated significant potentiation of cisplatin cytotoxicity in association with a reduction of BRCA1 protein. The cisplatin-resistant cell lines, T-47D and A2780s, elicited increased cytotoxicity of cisplatin with M344 and down regulation of BRCA1 protein levels. A2780s cells subjected to combination platinum and M344 treatment, demonstrated increased DNA damage as assessed by the presence of phosphorylated H2A.X foci in comparison to either treatment alone. Using Chromatin Immunoprecipitation, A2780s and MCF7 cells exposed to M344 alone and in combination with cisplatin, did not demonstrate enhanced acetylated Histone 4 at the BRCA1 promoter, suggesting an indirect effect on this promoter.ConclusionsThe enhanced sensitivity of HDAC inhibition to platinum may be mediated through a BRCA1-dependent mechanism in breast and ovarian cancer cells. The findings of this study may be important in the future design of clinical trials involving HDAC inhibitors using BRCA1 as a tumour biomarker.