BRCA1 Gene Expression in Breast Cancer: A Correlative Study between Real-time RT-PCR and Immunohistochemistry

Investigation of mRNA Expression Levels of Tip60 and Related DNA Repair Genes in Molecular Subtypes of Breast Cancer

INTRODUCTION

Studies in breast cancer (BC) have been shown that many tumor cells carry mutations that disrupt the DNA damage response mechanism. In eukaryotic cells, the overexpression or deprivation of DSBs repair genes is linked closely to a higher risk of cancer.

PATIENTS AND METHODS

In this study, mRNA expression levels of some genes, such as Tip60, ATM, p53, CHK2, BRCA1, H2AX, which are associated with DNA damage repair, were measured using RT-PCR method in tumor and matched-normal tissues of 58 patients with BC.

RESULTS

According to the study results, 55% in Tip60, 59% in ATM, 57% in BRCA1, 48% in H2AX, 66% in CHK2, and 43% in p53 decreased in tumor tissue of patients compared to the matched normal tissue. When evaluated according to molecular subtypes, expression of all genes in the pathway was found significantly higher in normal tissues than in tumor tissues especially in Luminal B and Luminal B+HER2 groups. One of the most important results of the study is that CHK2 mRNA expressions in normal tissues were higher than tumor tissue in 90% of patients in Luminal B and Luminal B-HER2 + groups. This is the first study showing DNA repair genes' expressions in molecular subtypes of breast cancer. In general, the decrease in the expression of DNA damage repair genes in tumor tissue indicates that these genes may have a role in the development of BC. Our study results also suggest that CHK2 may be a candidate marker in the molecular classification of breast cancer.

BRCA1 promoter methylation & its immunohistochemical correlation in sporadic breast cancer

Background & objectives

Studies have shown that apart from hereditary breast carcinomas, breast cancer susceptibility gene 1 (BRCA1) mutations conferring to its loss are seen in sporadic breast carcinomas (SBC) as well. The aim of the present study was to assess BRCA1 methylation in females presenting at King George's Medical University, Lucknow, with SBC by both immunohistochemistry (IHC) and methylation PCR with respect to hormonal profile and various morphological prognostic parameters. The primary objective was to look for the association between BRCA1 protein expression and DNA promoter methylation.

Methods

81 mastectomy specimens from SBC of invasive breast carcinoma (no special type) were included in this study. After a detailed morphological assessment, formalin fixed paraffin embedded tissue from a representative tumour area was selected for BRCA1 IHC by heat-mediated antigen retrieval under high pH and DNA extraction and further bisulphate treatment. BRCA1 was studied for methylation by methylated and unmethylated PCR-specific primers.

Results

BRCA1 promoter methylation was present in 42/81 (51.9%) participants, with significant BRCA1 protein loss (72.7%; P=0.002). A significant association between BRCA1 loss and hormonal profile was found (P=0.001); maximum in triple negative breast carcinoma (TNBC) (72%; 18/25). Most of the TNBC also harboured methylation (68%). Although not significant grade II and III tumours, lymph vascular invasion, ductal carcinoma in situ, and nodal metastasis (≥3) were seen in a higher percentage in methylated tumours. Mortality in SBC was significantly associated with BRCA1 loss (30.3%; P=0.024).

Interpretation & conclusions

Study results highlight the concept of "BRCAness" in SBC as well. Hence, we can confer that identification of BRCA1 loss in SBC can make it a perfect candidate for poly ADP-ribose polymerase inhibitors or cisplatin-based therapy like hereditary ones.

Loss of BRCA1 expression and morphological features associated with BRCA1 promoter methylation status in triple-negative breast cancer

Aberrant DNA methylation in the BRCA1 promoter region causes epigenetic silencing of BRCA1 gene expression, which is critical for breast cancer development. However, how BRCA1 promoter methylation status alters histological features remains poorly understood. Here, we investigated the possibility to predict BRCA1 promoter methylation status based on the morphological and immunohistochemical features of triple-negative breast cancers (TNBCs). The morphological features of 53 TNBCs were evaluated with hematoxylin-eosin staining, with immunohistochemical staining of BRCA1, androgen receptor, p53, cytokeratin 5/6, and epidermal growth factor receptor. BRCA1 promoter methylation status was used to distinguish BRCA1 promoter-methylated tumors (BPMTs) from BRCA1 promoter-unmethylated tumors (BPUTs) dependent on pathological characteristics. BPMTs comprised approximately 26% of the TNBCs. Immunohistochemical analysis found that BRCA1 protein expression was significantly lower in BPMT compared with BPUT (p = 0.016). Morphologically, BPMTs were associated with high mitotic index (p = 0.017), pushing margin (p = 0.017), a circumscribed growth pattern (p = 0.014), and a syncytial growth pattern (p = 0.034) compared with BPUTs. We then assessed the potential of predicting BRCA1 promoter methylation status by using published score systems based on these morphological characteristics. A receiver operating characteristic analysis showed an area under the curve of 0.80. This study found that BRCA1 promoter methylation status could be derived from morphological features and lower BRCA1 expression of TNBCs, which may help identify suitable cases for target treatment with PARP inhibitors.

BRCA1 Promoter Hypermethylation is Associated with Good Prognosis and Chemosensitivity in Triple-Negative Breast Cancer

The aberrant hypermethylation of BRCA1 promoter CpG islands induces the decreased expression of BRCA1 (Breast Cancer 1) protein. It can be detected in sporadic breast cancer without BRCA1 pathogenic variants, particularly in triple-negative breast cancers (TNBC). We investigated BRCA1 hypermethylation status (by methylation-specific polymerase chain reaction (MS-PCR) and MassARRAY^® assays), and BRCA1 protein expression using immunohistochemistry (IHC), and their clinicopathological significance in 248 chemotherapy-naïve TNBC samples. Fifty-five tumors (22%) exhibited BRCA1 promoter hypermethylation, with a high concordance rate between MS-PCR and MassARRAY^® results. Promoter hypermethylation was associated with reduced IHC BRCA1 protein expression (p = 0.005), and expression of Programmed death-ligand 1 protein (PD-L1) by tumor and immune cells (p = 0.03 and 0.011, respectively). A trend was found between promoter hypermethylation and basal marker staining (p = 0.058), and between BRCA1 expression and a basal-like phenotype. In multivariate analysis, relapse-free survival was significantly associated with N stage, adjuvant chemotherapy, and histological subtype. Overall survival was significantly associated with T and N stage, histology, and adjuvant chemotherapy. In addition, patients with tumors harboring BRCA1 promoter hypermethylation derived the most benefit from adjuvant chemotherapy. In conclusion, BRCA1 promoter hypermethylation is associated with TNBC sensitivity to adjuvant chemotherapy, basal-like features and PD-L1 expression. BRCA1 IHC expression is not a good surrogate marker for promoter hypermethylation and is not independently associated with prognosis. Association between promoter hypermethylation and sensitivity to Poly(ADP-ribose) polymerase PARP inhibitors needs to be evaluated in a specific series of patients.

Clinical significance of BRCA1 and BRCA2 mRNA and protein expression in patients with sporadic gastric cancer

The purpose of the present study was to investigate the clinical significance of BRCA1/BRCA2 DNA repair associated (BRCA1/BRCA2) gene expression in patients with sporadic gastric cancer (GC) who had received postoperative adjuvant chemotherapy. Breast cancer type 1 and 2 susceptibility protein (BRCA1 and BRCA2) expression and BRCA1/BRCA2 mRNA expression were evaluated using immunohistochemistry (IHC) and in-situ hybridization (ISH) on tissue GC microarray tissues, in addition to reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The results were analyzed for clinicopathological associations. A total of 367 cases of sporadic GC (stages II and III) were subjected to BRCA1 and BRCA2 expression analysis, and for BRCA1 and BRCA2 IHC, 360 cases were informative. A total of 61 cases (16.9%) displayed a loss of BRCA1 and 63 (17.5%) displayed a loss of BRCA2. BRCA1 and BRCA2 ISH results were obtained in 364 cases, of which 98 (26.9%) presented with low expression of BRCA1 mRNA and 148 (40.7%) with low expression of BRCA2 mRNA. In 72 of the 367 cases, BRCA1 and BRCA2 mRNA expression levels were assessed using RT-qPCR, of which 50 (69.4%) and 56 (77.8%) displayed low expression of BRCA1 and BRCA2, respectively. Positive IHC expression of BRCA2 was associated with advanced tumor stage; however, BRCA1 expression was not associated with any clinicopathological parameters. Associations between the RT-qPCR and ISH methods were not significant for either BRCA1 or BRCA2. The results of Kaplan-Meier survival analysis with stage subgrouping revealed no significant differences with regard to survival rate. Of the multivariate analyses, neither BRCA1 nor BRCA2 IHC results were independent prognostic factors. In summary, the present study indicated that BRCA1 and BRCA2, as assessed by IHC, may be used as clinicopathological biomarkers to evaluate the prognosis of sporadic GC.

Western Analysis of Breast Cancer 1 Protein (BRCA1)

Known for its tumor suppressor activity in breast and ovarian cancers, the breast cancer 1 susceptibility gene (Brca1) is involved in a variety of cellular pathways including DNA repair, antioxidant signaling, apoptosis, and cell cycle regulation. BRCA1 can translocate between the cytoplasm and nucleus to perform its various roles. Herein is a procedure for measuring BRCA1 protein levels in the whole cell lysate (WCL), as well as in the nuclear (N) and cytoplasmic (C) fractions of mouse tissues at different gestational ages. The method employs multiple loading controls to ensure proper separation of fractions and a total protein stain for more consistent comparisons of dissimilar samples. This method is useful for identifying BRCA1 deficiencies and localization in a variety of research fields, including development, neurodegeneration, and cancer.

A Physical Mechanism and Global Quantification of Breast Cancer

Initiation and progression of cancer depend on many factors. Those on the genetic level are often considered crucial. To gain insight into the physical mechanisms of breast cancer, we construct a gene regulatory network (GRN) which reflects both genetic and environmental aspects of breast cancer. The construction of the GRN is based on available experimental data. Three basins of attraction, representing the normal, premalignant and cancer states respectively, were found on the phenotypic landscape. The progression of breast cancer can be seen as switching transitions between different state basins. We quantified the stabilities and kinetic paths of the three state basins to uncover the biological process of breast cancer formation. The gene expression levels at each state were obtained, which can be tested directly in experiments. Furthermore, by performing global sensitivity analysis on the landscape topography, six key genes (HER2, MDM2, TP53, BRCA1, ATM, CDK2) and four regulations (HER2⊣TP53, CDK2⊣BRCA1, ATM→MDM2, TP53→ATM) were identified as being critical for breast cancer. Interestingly, HER2 and MDM2 are the most popular targets for treating breast cancer. BRCA1 and TP53 are the most important oncogene of breast cancer and tumor suppressor gene, respectively. This further validates the feasibility of our model and the reliability of our prediction results. The regulation ATM→MDM2 has been extensive studied on DNA damage but not on breast cancer. We notice the importance of ATM→MDM2 on breast cancer. Previous studies of breast cancer have often focused on individual genes and the anti-cancer drugs are mainly used to target the individual genes. Our results show that the network-based strategy is more effective on treating breast cancer. The landscape approach serves as a new strategy for analyzing breast cancer on both the genetic and epigenetic levels and can help on designing network based medicine for breast cancer.

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

AIMS

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.

METHODS

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.

RESULTS

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).

CONCLUSION

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.

Evaluation of BRCA1-related molecular features and microRNAs as prognostic factors for triple negative breast cancers

Background

The BRCA1 gene plays a key role in triple negative breast cancers (TNBCs), in which its expression can be lost by multiple mechanisms: germinal mutation followed by deletion of the second allele; negative regulation by promoter methylation; or miRNA-mediated silencing. This study aimed to establish a correlation among the BRCA1-related molecular parameters, tumor characteristics and clinical follow-up of patients to find new prognostic factors.

Methods

BRCA1 protein and mRNA expression was quantified in situ in the TNBCs of 69 patients. BRCA1 promoter methylation status was checked, as well as cytokeratin 5/6 expression. Maintenance of expressed BRCA1 protein interaction with BARD1 was quantified, as a marker of BRCA1 functionality, and the tumor expression profiles of 27 microRNAs were determined.

Results

miR-548c-5p was emphasized as a new independent prognostic factor in TNBC. A combination of the tumoral expression of miR-548c and three other known prognostic parameters (tumor size, lymph node invasion and CK 5/6 expression status) allowed for relapse prediction by logistic regression with an area under the curve (AUC) = 0.96.

BRCA1 mRNA and protein in situ expression, as well as the amount of BRCA1 ligated to BARD1 in the tumor, lacked any associations with patient outcomes, likely due to high intratumoral heterogeneity, and thus could not be used for clinical purposes.

Conclusions

In situ BRCA1-related expression parameters could be used for clinical purposes at the time of diagnosis. In contrast, miR-548c-5p showed a promising potential as a prognostic factor in TNBC.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1740-9) contains supplementary material, which is available to authorized users.

EPMA position paper in cancer: current overview and future perspectives

At present, a radical shift in cancer treatment is occurring in terms of predictive, preventive, and personalized medicine (PPPM). Individual patients will participate in more aspects of their healthcare. During the development of PPPM, many rapid, specific, and sensitive new methods for earlier detection of cancer will result in more efficient management of the patient and hence a better quality of life. Coordination of the various activities among different healthcare professionals in primary, secondary, and tertiary care requires well-defined competencies, implementation of training and educational programs, sharing of data, and harmonized guidelines. In this position paper, the current knowledge to understand cancer predisposition and risk factors, the cellular biology of cancer, predictive markers and treatment outcome, the improvement in technologies in screening and diagnosis, and provision of better drug development solutions are discussed in the context of a better implementation of personalized medicine. Recognition of the major risk factors for cancer initiation is the key for preventive strategies (EPMA J. 4(1):6, 2013). Of interest, cancer predisposing syndromes in particular the monogenic subtypes that lead to cancer progression are well defined and one should focus on implementation strategies to identify individuals at risk to allow preventive measures and early screening/diagnosis. Implementation of such measures is disturbed by improper use of the data, with breach of data protection as one of the risks to be heavily controlled. Population screening requires in depth cost-benefit analysis to justify healthcare costs, and the parameters screened should provide information that allow an actionable and deliverable solution, for better healthcare provision.

alphaB-crystallin is a marker of aggressive breast cancer behavior but does not independently predict for patient outcome: a combined analysis of two randomized studies

BACKGROUND

alphaB-crystallin is a small heat shock protein that has recently been characterized as an oncoprotein correlating with the basal core phenotype and with negative prognostic factors in breast carcinomas. The purpose of this study was to evaluate alphaB-crystallin with respect to clinicopathological parameters and the outcome of patients with operable high-risk breast cancer.

METHODS

A total of 940 tumors were examined, derived from an equal number of patients who had participated in two randomized clinical trials (paclitaxel-containing regimen in 793 cases). Immunohistochemistry for ER, PgR, HER2, Ki67, CK5, CK14, CK17, EGFR, alphaB-crystallin, BRCA1 and p53 was performed. BRCA1 mutation data were available in 89 cases.

RESULTS

alphaβ-crystallin was expressed in 170 cases (18.1%) and more frequently in triple-negative breast carcinomas (TNBC) (45% vs. 14.5% non-TNBC, p < 0.001). alphaB-crystallin protein expression was significantly associated with high Ki67 (Pearson chi-square test, p < 0.001), p53 (p = 0.002) and basal cytokeratin protein expression (p < 0.001), BRCA1 mutations (p = 0.045) and negative ER (p < 0.001) and PgR (p < 0.001). Its overexpression, defined as >30% positive neoplastic cells, was associated with adverse overall survival (Wald's p = 0.046). However, alphaB-crystallin was not an independent prognostic factor upon multivariate analysis. No interaction between taxane-based therapy and aβ-crystallin expression was observed.

CONCLUSIONS

In operable high-risk breast cancer, alphaB-crystallin protein expression is associated with poor prognostic features indicating aggressive tumor behavior, but it does not seem to have an independent impact on patient survival or to interfere with taxane-based therapy.

TRIAL REGISTRATIONS

ACTRN12611000506998 (HE10/97 trial) and ACTRN12609001036202 (HE10/00 trial).

A BRCA1 deficient-like signature is enriched in breast cancer brain metastases and predicts DNA damage-induced poly (ADP-ribose) polymerase inhibitor sensitivity

INTRODUCTION

There is an unmet clinical need for biomarkers to identify breast cancer patients at an increased risk of developing brain metastases. The objective is to identify gene signatures and biological pathways associated with human epidermal growth factor receptor 2-positive (HER2+) brain metastasis.

METHODS

We combined laser capture microdissection and gene expression microarrays to analyze malignant epithelium from HER2+ breast cancer brain metastases with that from HER2+ nonmetastatic primary tumors. Differential gene expression was performed including gene set enrichment analysis (GSEA) using publicly available breast cancer gene expression data sets.

RESULTS

In a cohort of HER2+ breast cancer brain metastases, we identified a gene expression signature that anti-correlates with overexpression of BRCA1. Sequence analysis of the HER2+ brain metastases revealed no pathogenic mutations of BRCA1, and therefore the aforementioned signature was designated BRCA1 Deficient-Like (BD-L). Evaluation of an independent cohort of breast cancer metastases demonstrated that BD-L values are significantly higher in brain metastases as compared to other metastatic sites. Although the BD-L signature is present in all subtypes of breast cancer, it is significantly higher in BRCA1 mutant primary tumors as compared with sporadic breast tumors. Additionally, BD-L signature values are significantly higher in HER2-/ER- primary tumors as compared with HER2+/ER + and HER2-/ER + tumors. The BD-L signature correlates with breast cancer cell line pharmacologic response to a combination of poly (ADP-ribose) polymerase (PARP) inhibitor and temozolomide, and the signature outperformed four published gene signatures of BRCA1/2 deficiency.

CONCLUSIONS

A BD-L signature is enriched in HER2+ breast cancer brain metastases without pathogenic BRCA1 mutations. Unexpectedly, elevated BD-L values are found in a subset of primary tumors across all breast cancer subtypes. Evaluation of pharmacological sensitivity in breast cancer cell lines representing all breast cancer subtypes suggests the BD-L signature may serve as a biomarker to identify sporadic breast cancer patients who might benefit from a therapeutic combination of PARP inhibitor and temozolomide and may be indicative of a dysfunctional BRCA1-associated pathway.

Differing effects of adjuvant chemotherapy according to BRCA1 nuclear expression in gastric cancer

BACKGROUND

We aimed to investigate the role of BRCA1 nuclear expression in sporadic gastric cancer; currently, the role remains unknown.

METHODS

Patients with gastric cancer who received curative operation with D2 dissection were enrolled in this study. Adjuvant chemotherapy was administered at the discretion of the physician. According to BRCA1 nuclear expression analysis by immunohistochemistry (IHC) on tissue microarrays using anti-BRCA1 antibody MS110, BRCA1 expression was classified as negative, low expression, and high expression.

RESULTS

Among 318 cases, 155 cases (48.7 %) were identified as BRCA1-negative by IHC and 96 cases (30.2 %) revealed BRCA1 low expression, 67 cases (21.0 %) showed BRCA1 high expression. The negative or reduced expression of BRCA1 was more frequent in more advanced-stage disease (p < 0.001) and was associated with perineural invasion (p = 0.032). Disease-free survival (DFS) was significantly decreased with reduced BRCA1 expression (p = 0.027). This tendency was also observed in overall survival (OS), although the difference was not significant. The poorer prognosis of BRCA1-negative tumors was overcome through adjuvant chemotherapy. The benefit of adjuvant chemotherapy for DFS and OS in stage III was enhanced only in BRCA1-negative tumors (p < 0.001, p < 0.001, respectively), but not in BRCA1-positive tumors (p = 0.236, p = 0.148, respectively).

CONCLUSION

The reduction of BRCA1 nuclear expression is associated with advanced stage and perineural invasion. Moreover, negative BRCA1 nuclear expression is a predictive marker regarding the benefit of adjuvant chemotherapy in sporadic gastric cancer; these novel findings are of great importance, and further, larger studies are warranted.

The BRCA1 Breast Cancer Suppressor: Regulation of Transport, Dynamics, and Function at Multiple Subcellular Locations

Inherited mutations in the BRCA1 gene predispose to a higher risk of breast/ovarian cancer. The BRCA1 tumor suppressor is a 1863 amino acid protein with multiple protein interaction domains that facilitate its roles in regulating DNA repair and maintenance, cell cycle progression, transcription, and cell survival/apoptosis. BRCA1 was first identified as a nuclear phosphoprotein, but has since been shown to contain different transport sequences including nuclear export and nuclear localization signals that enable it to shuttle between specific sites within the nucleus and cytoplasm, including DNA repair foci, centrosomes, and mitochondria. BRCA1 nuclear transport and ubiquitin E3 ligase enzymatic activity are tightly regulated by the BRCA1 dimeric binding partner BARD1 and further modulated by cancer mutations and diverse signaling pathways. This paper will focus on the transport, dynamics, and multiple intracellular destinations of BRCA1 with emphasis on how regulation of these events has impact on, and determines, a broad range of important cellular functions.

Hypoxia-induced protein CAIX is associated with somatic loss of BRCA1 protein and pathway activity in triple negative breast cancer

The purpose of this study is to explore the relationship between tumor hypoxia assessed by CA IX protein expression and loss of BRCA1 function in triple negative breast cancer (TNBC). Protein expression of CA IX and BRCA1 was evaluated by AQUA™ technology on two breast cancer cohorts: an unselected cohort of 637 breast cancer patients and a TNBC cohort of 120 patients. Transcriptional profiling was performed on FFPE samples from the TNBC cohort to evaluate a gene expression signature associated with BRCA1 mutation (van't Veer et al., Nature 415(6871):530-536, 2002). CA IX is expressed in 7 % of the unselected breast cancer cohort and in 25 % of the TNBCs and is significantly associated with the triple negative phenotype. CA IX protein expression and BRCA1 protein expression are inversely correlated in both cohorts. Patients expressing high levels of CA IX show significantly worse overall survival (p = 0.02). Importantly, high CA IX protein expression occurs in patients who show the BRCA1 mutant signature and low levels of BRCA1 protein. These data suggest that elevated CA IX protein in TNBC is associated with a BRCA1 mutant signature and loss of BRCA1 function. CA IX may be a useful biomarker to identify triple negative patients with defective homologous recombination, who might benefit from PARP inhibitor therapy.

Aberrant Expression of Cancer Stem Cells Marker Prominin-1 in Low-Grade Tubulolobular Breast Carcinoma: A Correlative Study between qRT-PCR, Flow-Cytometric and Immunohistochemistry Analysis [corrected]

Purpose

Prominin1/CD133 has become the ideal marker for cancer stem cells (CSCs) detection in human tumors. In this study we examined the expression of this marker in several breast cancer specimens to associate CSCs percentage with risk factor for this neoplasia.

Methods

We examined specimens from 12 patients using CD133 and CD44 antibodies for CSCs immunohistochemistry detection and for flow cytometry analysis. For each patient, we also performed the immunohistochemical staining to evaluate the expression of estrogen receptor, progesterone receptor, c-erbB-2, Ki67, and E-cadherin markers. A Taqman probe for CD133 was used for mRNA quantification by real-time polymerase chain reaction.

Results

Prominin-1 expression was heterogeneous in different carcinomas but was strikingly hyperexpressed in a tubulolobular variant of breast cancer. The results were confirmed by all three methods.

Conclusion

Our data, although produced on a limited number of samples, showed an particularly high expression of stem cell marker CD133 in a breast cancer variant, generally with a good prognosis. Since CSCs detection by CD133 has been described as an important prognostic factor for several human cancers, we suggest the importance of detecting stem cell compartiments in all histotypes of breast carcinomas.

BRCAness profile of sporadic ovarian cancer predicts disease recurrence

Background

The consequences of defective homologous recombination (HR) are not understood in sporadic ovarian cancer, nor have the potential role of HR proteins other than BRCA1 and BRCA2 been clearly defined. However, it is clear that defects in HR and other DNA repair pathways are important to the effectiveness of current therapies. We hypothesize that a subset of sporadic ovarian carcinomas may harbor anomalies in HR pathways, and that a BRCAness profile (defects in HR or other DNA repair pathways) could influence response rate and survival after treatment with platinum drugs. Clinical availability of a BRCAness profile in patients and/or tumors should improve treatment outcomes.

Objective

To define the BRCAness profile of sporadic ovarian carcinoma and determine whether BRCA1, PARP, FANCD2, PTEN, H2AX, ATM, and P53 protein expression correlates with response to treatment, disease recurrence, and recurrence-free survival.

Materials and Methods

Protein microarray analysis of ovarian cancer tissue was used to determine protein expression levels for defined DNA repair proteins. Correlation with clinical and pathologic parameters in 186 patients with advanced stage III–IV and grade 3 ovarian cancer was analyzed using Chi square, Kaplan-Meier method, Cox proportional hazard model, and cumulative incidence function.

Results

High PARP, FANCD2 and BRCA1 expressions were significantly correlated with each other; however, elevated p53 expression was associated only with high PARP and FANCD2. Of all patients, 9% recurred within the first year. Among early recurring patients, 41% had high levels of PARP, FANCD2 and P53, compared to 19.5% of patients without early recurrence (p = 0.04). Women with high levels of PARP, FANCD2 and/or P53 had first year cumulative cancer incidence of 17% compared with 7% for the other groups (P = 0.03).

Conclusions

Patients with concomitantly high levels of PARP, FANCD2 and P53 protein expression are at increased risk of early ovarian cancer recurrence and platinum resistance.

Loss of BRCA1 protein expression as indicator of the BRCAness phenotype is associated with favorable overall survival after complete resection of sporadic ovarian cancer

OBJECTIVE

Hereditary epithelial ovarian cancers (EOCs) not expressing functional BRCA1 protein are characterized by defects in homologous recombination DNA repair, rendering such tumors more sensitive to DNA damaging agents and synthetic lethality, that is, poly-ADP-ribose-polymerase inhibitor treatment. The aim of this study was to evaluate the use of BRCA1 immunohistochemistry (IHC) for EOC prognosis and identification of features of the BRCAness phenotype.

METHODS

Twenty-seven patients who were treated for advanced EOC by macroscopic complete surgical tumor resection and first-line carboplatin/paclitaxel treatment were included. Time to recurrence and overall survival time after initial surgery were determined, and patients' samples were evaluated for BRCA1 expression by IHC. BRCA1 messenger RNA expression and promoter methylation was analyzed to elucidate regulatory mechanisms involved in BRCA1 protein loss.

RESULTS

BRCA1 IHC-negative patients had a significantly longer overall survival (crude rate, 1537 days) compared to the BRCA1 IHC-positive group (crude rate, 827 days; P = 0.01). The patients in the BRCA1 IHC-negative group were significantly younger (51 years) compared to BRCA1 IHC-positive patients (61 years; P < 0.01). Importantly, both transcriptional and posttranscriptional mechanisms regulate BRCA1 protein expression. Only protein but not messenger RNA level were associated with longer overall survival.

CONCLUSION

Epithelial ovarian cancers with negative BRCA1 protein expression were identified in younger patients, showed a significantly better overall survival, prolonged treatment intervals and a tendency for an extended progression free time interval. BRCA1 IHC negativity of sporadic EOC may be predictive of sensitivity to platinum-based chemotherapy and the poly-ADP-ribose-polymerase inhibitor-sensitive BRCAness phenotype.

PARP inhibition induces BAX/BAK-independent synthetic lethality of BRCA1-deficient non-small cell lung cancer

Evasion of apoptosis contributes to both tumourigenesis and drug resistance in non-small cell lung carcinoma (NSCLC). The pro-apoptotic BCL-2 family proteins BAX and BAK are critical regulators of mitochondrial apoptosis. New strategies for targeting NSCLC in a mitochondria-independent manner should bypass this common mechanism of apoptosis block. BRCA1 mutation frequency in lung cancer is low; however, decreased BRCA1 mRNA and protein expression levels have been reported in a significant proportion of lung adenocarcinomas. BRCA1 mutation/deficiency confers a defect in homologous recombination DNA repair that has been exploited by synthetic lethality through inhibition of PARP (PARPi) in breast and ovarian cells; however, it is not known whether this same synthetic lethal mechanism exists in NSCLC cells. Additionally, it is unknown whether the mitochondrial apoptotic pathway is required for BRCA1/PARPi-mediated synthetic lethality. Here we demonstrate that silencing of BRCA1 expression by RNA interference sensitizes NSCLC cells to PARP inhibition. Importantly, this sensitivity was not attenuated in cells harbouring mitochondrial apoptosis block induced by co-depletion of BAX and BAK. Furthermore, we demonstrate that BRCA1 inhibition cannot override platinum resistance, which is often mediated by loss of mitochondrial apoptosis signalling, but can still sensitize to PARP inhibition. Finally we demonstrate the existence of a BRCA1-deficient subgroup (11-19%) of NSCLC patients by analysing BRCA1 protein levels using immunohistochemistry in two independent primary NSCLC cohorts. Taken together, the existence of BRCA1-immunodeficient NSCLC suggests that this molecular subgroup could be effectively targeted by PARP inhibitors in the clinic and that PARP inhibitors could be used for the treatment of BRCA1-immunodeficient, platinum-resistant tumours.

Identification of BRCA1-deficient ovarian cancers

OBJECTIVE

It is believed that 24-40% of ovarian cancers have dysfunction in the BRCA1 or BRCA2 (BRCAness) genes, due to either inherited or somatic mutations or due to epigenetic inactivation. Demonstration of ovarian cancers with BRCAness is becoming important both due to the possibility of offering genetic counseling and due to beneficial effects of polyadenosine diphosphate ribose polymerase inhibitor treatment in this group. As DNA sequencing is expensive and time consuming, efforts have been devoted to develop more indirect methods for BRCA screening that can improve the selection of patients for sequence-based BRCA testing.

DESIGN

BRCA1 immunohistochemistry, fluorescence in situ hybridization (FISH) and methylation analyses were performed on formalin-fixed, paraffin-embedded ovarian cancer tissue.

SAMPLE

Fifty-four ovarian cancers; 15 BRCA1 cancers, four BRCA2 cancers, 10 cancers from patients with a family history but no mutation detected, and 25 ovarian cancers with unknown BRCA1 status.

RESULTS

Abnormal BRCA1 immunohistochemistry was found to indicate BRCA mutations with a sensitivity of 80%, a specificity of 93% and an estimated positive predictive value of 73%. The FISH analyses supported the diagnosis in most cases. Methylation analyses could indicate BRCA deficiency in combination with one of the other methods.

CONCLUSIONS

BRCA1 immunohistochemistry is a promising screening method for BRCA1 mutation detection.

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

BACKGROUND

Breast 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 METHODS

In 251 patient samples from the NCIC CTG clinical trial, OV.16, BRCA1 protein expression was determined by immunohistochemistry.

RESULTS

For 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].

CONCLUSIONS

This 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.

The expression of ERCC1, RRM1, and BRCA1 in breast cancer according to the immunohistochemical phenotypes

We studied the expression of BRCA1, ERCC1, and RRM1 which play an important role in DNA repair systems in breast cancer. Immunohistochemical staining for EGFR, BRCA1, ERCC1, and RRM1 were performed by using a tissue microarray made from 230 breast cancer patients. Patients were classified into luminal A, luminal B, HER-2, and triple negative breast cancer (TNBC) types according to ER, PR, and HER-2 expression. The expression of ERCC1, RRM1, and BRCA1 were correlated (P < 0.05). The expression level of ERCC1 was the lowest in TNBC type (P = 0.031), ERCC1 negativity was more prominent in TNBC and luminal B groups than luminal A and HER-2 groups (P = 0.013). Cases with EGFR overexpression showed high expression of RRM1 and BRCA1 (P = 0.046, and 0.004, respectively). In conclusion, the expression of ERCC1 is particularly lower in TNBCs than other types of breast cancers.

Expression of DNA repair genes in ovarian cancer samples: biological and clinical considerations

The purpose of this study was to investigate retrospectively the mRNA expression of genes involved in different DNA repair pathways implicated in processing platinum-induced damage in 171 chemotherapy-naïve ovarian tumours and correlate the expression of the different genes with clinical parameters. The expression of genes involved in DNA repair pathways (PARP1, ERCC1, XPA, XPF, XPG, BRCA1, FANCA, FANCC, FANCD2, FANCF and PolEta), and in DNA damage transduction (Chk1 and Claspin) was measured by RT-PCR in 13 stage I borderline and 77 stage I and 88 III ovarian carcinomas. ERCC1, XPA, XPF and XPG genes were significantly less expressed in stage III than in stage I carcinoma; BRCA1, FANCA, FANCC, FANCD2 gene expressions were low in borderline tumours, higher in stage I carcinomas and lower in stage III samples. High levels of ERCC1, XPA, FANCC, XPG and PolEta correlated with an increase in Overall Survival (OS) and Progression Free Survival (PFS), whilst high BRCA1 levels were associated with PFS on univariate analysis. With multivariate analyses no genes retained an association when adjusted by stage, grade and residual tumour. A tendency towards a better PFS was observed in patients with the highest level of ERCC1 and BRCA1 after platinum-based therapy than those given both platinum and taxol. The expression of DNA repair genes differed in borderline stage I, stage I and stage III ovarian carcinomas. The role of DNA repair genes in predicting the response in ovarian cancer patients seems far from being established.

Gene promoter methylation is associated with increased mortality among women with breast cancer

To better understand breast cancer etiology and progression, we explored the association between promoter methylation status of three breast cancer-related genes (BRCA1, APC, and p16) and survival in a large cohort of women with breast cancer. About 800 archived tumor tissues were collected from women diagnosed with a first primary invasive or in situ breast cancer in 1996-1997. The vital status of the participants was followed through the end of year 2005 with a mean follow-up time of 8.0 years. Promoter methylation was assessed by methylation-specific PCR (for BRCA1) and MethyLight (for APC and p16). The association of promoter methylation and breast cancer mortality was evaluated by Cox-proportional hazards models. Methylated promoters were found in 59.0, 48.4, and 3.6% of the tumor samples for BRCA1, APC, and p16, respectively. Breast cancer-specific mortality was strongly associated with promoter methylation of p16 [HR and 95% CI: 3.53 (1.83-6.78)], whereas the associations with of BRCA1 and APC were less pronounced [HR and 95% CI: 1.81 (1.18-2.78) and 1.46 (0.98-2.17), respectively]. Similar associations were observed with all-cause mortality. As the number of methylated genes increased, the risk of breast cancer-specific mortality also increased in a dose-dependent manner (P, trend = 0.01). Importantly, even with our results stratified by hormone receptor status, promoter methylation of the three genes remained predictive of mortality. Our results suggest that promoter methylation could be promising epigenetic markers to be considered for breast cancer survival.

Aberrant methylation profile of 14-3-3 sigma and its reduced transcription/expression levels in Chinese sporadic female breast carcinogenesis

To study the relation of 14-3-3 sigma gene promoter hypermethylation and its transcription expression levels in sporadic breast carcinogenesis. Methylation of 14-3-3 sigma gene was detected by sensitive MSP assay in carcinous, non-cancerous, and normal tissue, and its mRNA was also detected by real time PCR based on SYBR Green 1 as well, and protein was detected by west blotting assay. The methylation frequencies of 14-3-3 sigma were 90% in 68 cases of sporadic breast cancer patients. Methylation was presented in portions (2/13, 18%) of hyperplastic samples, and no hypermethylation was presented in normal tissue. The methylation change of 14-3-3 sigma gene was markedly related with various types, grades, and lymph node metastases (P < 0.05), and no significant differences in methylation frequencies were seen between premenopause and postmenopause (P > 0.05). The methylation of 14-3-3 sigma shows reverse relation with its mRNA transcription and expression level (P < 0.05). Only was lymph node metastases strongly associated with poor outcome (P = 0.02). Whether 14-3-3 sigma promoter methylation or not did not affect the 5 years survival rate of sporadic breast cancer patients (P > 0.05). Epigenetics alterations of the 14-3-3 sigma can contribute to reducing or losing expression of 14-3-3 sigma protein, which play an important role in the development of sporadic breast carcinomas and involved in various types, grades, and lymph node metastases. Otherwise, node metastases of breast carcinogenesis patients are strongly associated with poor outcome.

BRCA1 promoter methylation is associated with increased mortality among women with breast cancer

Promoter-CpG island hypermethylation has been proposed as an alternative mechanism to inactivate BRCA1 in the breast where somatic mutations of BRCA1 are rare. To better understand breast cancer etiology and progression, we explored the association between BRCA1 promoter methylation status and prognostic factors as well as survival among women with breast cancer. Promoter methylation of BRCA1 was assessed in 851 archived tumor tissues collected from a population-based study of women diagnosed with invasive or in situ breast cancer in 1996-1997, and who were followed for vital status through the end of 2002. About 59% of the tumors were methylated at the promoter of BRCA1. The BRCA1 promoter methylation was more frequent in invasive cancers (P = 0.02) and among premenopausal cases (P = 0.05). BRCA1 promoter methylation was associated with increased risk of breast cancer-specific mortality (age-adjusted HR 1.71; 95% CI: 1.05-2.78) and all-cause mortality (age-adjusted HR 1.49; 95% CI: 1.02-2.18). Neither dietary methyl intakes in the year prior to the baseline interview nor the functional polymorphisms in one-carbon metabolism were associated with BRCA1 methylation status. Our study is the first epidemiological investigation on the prognostic value of BRCA1 promoter methylation in a large population-based cohort of breast cancer patients. Our results indicate that BRCA1 promoter methylation is an important factor to consider in predicting breast cancer survival.

Expression profile of BRCA1 and BRCA2 genes in premenopausal Mexican women with breast cancer: clinical and immunohistochemical correlates

Low BRCA1 gene expression is associated with increased invasiveness and influences the response of breast carcinoma (BC) to chemotherapeutics. However, expression of BRCA1 and BRCA2 genes has not been completely characterized in premenopausal BC. We analyzed the clinical and immunohistochemical correlates of BRCA1 and BRCA2 expression in young BC women. We studied 62 women (mean age 38.8 years) who developed BC before the age of 45 years. BRCA1 and BRCA2 mRNA expression was assessed by reverse transcriptase-polymerase chain reaction (RT-PCR) and that of HER-2 and p53 proteins by immunohistochemistry. Body mass index (BMI) > or = 27 (52%) and a declared family history of BC (26%) were the main risk factors. Ductal infiltrative adenocarcinoma was found in 86% of the cases (tumor size >5 cm in 48%). Disease stages I-IV occurred in 2, 40, 55, and 3%, respectively (73% implicating lymph nodes). Women aged < or = 35 years (24%) had more family history of cervical cancer, stage III/IV disease, HER-2 positivity, and lower BRCA1 expression than older women (P < 0.05). BRCA1 and BRCA2 expression correlated in healthy, but not in tumor tissues (TT). Neither BRCA1 nor BRCA2 expression was associated with tumor histology, differentiation, nodal metastasis or p53 and HER-2 expression. After multivariate analysis, only disease stage explained BRCA1 mRNA levels in the lowest quartile. Premenopausal BC has aggressive clinical and molecular characteristics. Low BRCA1 mRNA expression is associated mainly with younger ages and advanced clinical stage of premenopausal BC. BRCA2 expression is not associated with disease severity in young BC women.

Induction and processing of complex DNA damage in human breast cancer cells MCF-7 and nonmalignant MCF-10A cells

Oxidatively induced stress and DNA damage have been associated with various human pathophysiological conditions, including cancer and aging. Complex DNA damage such as double-strand breaks (DSBs) and non-DSB bistranded oxidatively induced clustered DNA lesions (OCDL) (two or more DNA lesions within a short DNA fragment of 1-10 bp on opposing DNA strands) are hypothesized to be repair-resistant lesions challenging the repair mechanisms of the cell. To evaluate the induction and processing of complex DNA damage in breast cancer cells exposed to radiotherapy-relevant gamma-ray doses, we measured single-strand breaks (SSBs), DSBs, and OCDL in MCF-7 and HCC1937 malignant cells as well as MCF-10A nonmalignant human breast cells. For the detection and measurement of SSBs, DSBs, and OCDL, we used the alkaline single-cell gel electrophoresis, gamma-H2AX assay, and an adaptation of pulsed-field gel electrophoresis with E. coli repair enzymes as DNA damage probes. Increased levels for most types of DNA damage were detected in MCF-7 cells while the processing of DSBs and OCDL was deficient in these cells compared to MCF-10A cells. Furthermore, the total antioxidant capacity of MCF-7 cells was lower compared to their nonmalignant counterparts. These findings point to the important role of complex DNA damage in breast cancer and its potential association with breast cancer development especially in the case of deficient BRCA1 expression.

Familial breast/ovarian cancer and BRCA1/2 genetic screening: the role of immunohistochemistry as an additional method in the selection of patients

Only 20-25% of families screened for BRCA1/2 mutations are found positive. Because only a positive result is informative, we studied the role of BRCA1/2 immunohistochemistry as an additional method for patient selection. From 53 high-risk-affected probands, 18 (34%) had available paraffin blocks of their tumors and were selected for this study. Mutation screening was done by conformation-sensitive gel electrophoresis and multiplex ligation-dependent probe amplification. For immunohistochemistry, 21 neoplastic specimens (15 breast carcinomas, 5 ovary neoplasms, and 1 rectal adenocarcinoma) were analyzed with BRCA1 (monoclonal antibody, Ab-1, oncogene) and BRCA2 (polyclonal antibody, Ab-2, oncogene) antibodies. Absence of the BRCA1 protein was confirmed in negative tumors by Western blotting. Seven patients were positive for BRCA1/2 mutations: 5 for BRCA1 and 2 for BRCA2. Four out of five positive patients had tumors negative for BRCA1 immunostaining, and the remaining 13 BRCA1-negative patients had positive BRCA1 immunostaining in all tumor samples. Sensitivity to predict for BRCA1 mutation carriers was 80%, and specificity was 100%, with a positive predictive value of 100% and a negative predictive value of 93%. This correlation was statistically significant (p=0.001). No correlation was observed for BRCA2. If larger studies confirm these results, high-risk patients with BRCA1-negative tumors should be screened first for this gene.

Does aneuploidy cause cancer?

Aneuploidy has been recognized as a common characteristic of cancer cells for >100 years. Aneuploidy frequently results from errors of the mitotic checkpoint, the major cell cycle control mechanism that acts to prevent chromosome missegregation. The mitotic checkpoint is often compromised in human tumors, although not as a result of germline mutations in genes encoding checkpoint proteins. Less obviously, aneuploidy of whole chromosomes rapidly results from mutations in genes encoding several tumor suppressors and DNA mismatch repair proteins, suggesting cooperation between mechanisms of tumorigenesis that were previously thought to act independently. Cumulatively, the current evidence suggests that aneuploidy promotes tumorigenesis, at least at low frequency, but a definitive test has not yet been reported.

BRCA1 suppresses osteopontin-mediated breast cancer

BRCA1 is a well described breast cancer susceptibility gene thought to be involved primarily in DNA repair. However, mutation within the BRCA1 transcriptional domain is also implicated in neoplastic transformation of mammary epithelium, but responsible mechanisms are unclear. Here we show in a rat mammary model system that wild type (WT) BRCA1 specifically represses the expression of osteopontin (OPN), a multifunctional estrogen-responsive gene implicated in oncogenic transformation, particularly that of the breast. WT.BRCA1 selectively binds OPN-activating transcription factors estrogen receptor alpha, AP-1, and PEA3, inhibits OPN promoter transactivation, and suppresses OPN mRNA and protein both from an endogenous gene and a relevant model inducible gene. WT.BRCA1 also inhibits OPN-mediated neoplastic transformation characterized by morphology change, anchorage-independent growth, adhesion to fibronectin, and invasion through Matrigel. A mutant BRCA1 allele (Mut.BRCA1) associated with familial breast cancer lacks OPN suppressor effects, binds to WT.BRCA1, and impedes WT.BRCA1 suppression of OPN. Stable transfection of rat breast tumor cell lines with Mut.BRCA1 dramatically up-regulates OPN protein and induces anchorage independent growth. In human primary breast cancer, BRCA1 mutation is significantly associated with OPN overexpression. Taken together, these data suggest that BRCA1 mutation may confer increased tissue-specific cancer risk, in part by disruption of BRCA1 suppression of OPN gene transcription.