• Molecules and Cells
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• v.25 no.4
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• pp.457-461
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• 2008

DNA damage checkpoint is an important self-defense mechanism for the maintenance of genome stability. Defects in DNA damage signaling and repair lead to various disorders and increase tumor incidence in humans. In the past 10 years, we have identified many components involved in the DNA damage-signaling pathway, including the product of breast cancer susceptibility gene 1 (BRCA1). Mutations in BRCA1 are associated with increased risk of breast and ovarian cancers, highlighting the importance of this DNA damage-signaling pathway in tumor suppression. While it becomes clear that BRCA1 plays a crucial role in the DNA damage responsive pathway, exactly how BRCA1 receives DNA damage signals and exerts its checkpoint function has not been fully addressed. A series of recent studies reported the discovery of many novel components involved in DNA damage-signaling pathway. These newly identified checkpoint proteins, including RNF8, RAP80 and CCDC98, work in concern in recruiting BRCA1 to DNA damage sites and thus regulate BRCA1 function in G2/M checkpoint control. This review will summarize these recent findings and provide an updated view of the regulation of BRCA1 in response to DNA damage.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.4
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• pp.1987-1991
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• 2016

Breast cancer has emerged as the most prevalent cancer among women worldwide, including in Indonesia. The contribution of genes associated with high-risk breast-ovarian cancers, BRCA1 and BRCA2, in the Indonesian population is relatively unknown. We have characterized family history of patients with moderate- to high-risk of breast cancer predisposition in 26 unrelated cases from Indonesia for BRCA1/2 mutation analyses using direct sequencing. Known deleterious mutations were not found in either BRCA1 or BRCA2 genes. Seven variants in BRCA2 were documented in 10 of 26 patients (38%). All variants were categorized as unclassified (VUSs). Two synonymous variants, c.3623A>G and c.4035T>C, were found in 5 patients. One variant, c4600T>C, was found in a 38 year old woman with a family history of breast cancer. We have found 4 novel variants in BRCA2 gene including c.6718C>G, c.3281A>G, c.10176C>G, and c4490T>C in 4 unrelated patients, all of them having a positive family history of breast cancer. In accordance to other studies in Asian population, our study showed more frequent variants in BRCA2 compared to BRCA1. Further studies involving larger numbers of hereditary breast cancer patients are required to reveal contribution of BRCA1/2 mutations and/or other predisposing genes among familial breast cancer patients in Indonesia.

• BMB Reports
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• v.40 no.1
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• pp.15-21
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• 2007

Breast cancer is the most common malignancy among women, and mutations in the BRCA1 gene produce increased susceptibility to these malignancies in certain families. In this study, the forward 1-13 exons of breast cancer associated gene BRCA1 were cloned from breast cancer cell line ZR-75-30 by RT-PCR method. Sequence analysis showed that nine BRCA1 splice forms were isolated and characterized, compared with wild-type BRCA1 gene, five splice forms of which were novel. These splice isoforms were produced from the molecular mechanism of 5' and 3' alternative splicing. All these splice forms deleting exon 11b and the locations of alternative splicing were focused on two parts:one was exons 2 and 3, and the other was exons 9 and 10. These splice forms accorded with GT-AG rule. Most these BRCA1 splice variants still kept the original reading frame. Western blot analysis indicated that some BRCA1 splice variants were expressed in ZR-75-30 cell line at the protein level. In addition, we confirmed the presence of these new transcripts of BRCA1 gene in MDA-MB-435S, K562, Hela, HLA, HIC, H9, Jurkat and human fetus samples by RT-PCR analysis. These results suggested that breast cancer associated gene BRCA1 may have unexpectedly a large number of splice variants. We hypothesized that alternative splicing of BRCA1 possibly plays a major role in the tumorigenesis of breast and/or ovarian cancer. Thus, the identification of cancer-specific splice forms will provide a novel source for the discovery of diagnostic or prognostic biomarkers and tumor antigens suitable as targets for therapeutic intervention.

• Genomics & Informatics
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• v.3 no.4
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• pp.154-158
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• 2005

Germ-line mutations of the BRCA1 gene confer an increased risk for breast and ovarian cancers. BRCA1 in female cells is directly related with the maintenance of the inactive X chromosome (Xi). The effect by the loss of the BRCA1 function on the X chromosome gene expression remains unclear in cancer cells. We attempted to investigate the expression pattern of the X-linked genes by performing BRCA1 knockdown via RNA interference in the MCF7 breast cancer cell line. The transcriptional and translational levels of BRCA1 were decreased over 95% in the MCF7 cells after BRCA1 knockdown. The expression patterns of one hundred ninety X-linked genes were profiled by the X chromosome-specific cDNA arrays. A total of seven percent of the X-linked genes (14/190) were aberrantly expressed by over 2-fold in the MCF7-BRCA1 knockdown cells, which contained two up-regulated genes (2/190, 1 %) and 12 down-regulated genes (12/190, 6.3%). It is interesting that 72% of the aberrantly expressed X-linked genes were located on the Xq (10/14,) region. Our data suggests that BRCA1 may not be important to maintain X chromosome inactivation in cancer because the BRCA1 knockdown did increase the expression of the only one percent of X-linked genes in the human breast cancer cells.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.10
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• pp.4275-4279
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• 2014

Background: The aim of this work is to assess the frequency of BRCA1 protein immunohistochemical (IHC) expression in epithelial ovarian cancer (EOC) and to evaluate the association of BRCA1 expression with clinical and pathological characteristics and the overall survival (OS) of patients treated with postoperative platinum-based chemotherapeutic agents. Materials and Methods: This retrospective study was conducted on 35 cases of epithelial ovarian cancer selected from the files of the Pathology Department, Faculty of Medicine, Mansoura University, Egypt. Immunohistochemistry (IHC) was performed for BRCA1 gene protein. BRCA1 expression was compared to patient's age, tumor histology, grade, stage and OS time. Statistical analysis was carried out with the SPSS version 16.0 to assess significant associations. Results: BRCA1 nuclear expression was detected in 40% of EOC, in which a mild increase in the percentage of positive cases was observed with serous histology, stage IV, and grade 3 carcinomas. There was a significant statistical difference in BRCA1 expression with regard to histological subtypes of EOC (p=0.048), but not grade or stage. Mean OS and survival rate were slightly better for BRCA1 expressing group, but there was no statistically significant difference (p=0.528). Conclusions: No association between BRCA1 immunohistochemical expression and tumor grade, stage or overall survival was noted in platinum-treated epithelial ovarian cancer patients.

• Radiation Oncology Journal
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• v.21 no.2
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• pp.149-157
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• 2003

Purpose: The purpose of this study was to determine if there were prognostic differences between BRCA related and BRCA non-related Korean patients with early-onset breast carcinomas. Materials and Methods: Sixty women who had developed breast cancers before the age of 40, and who were treated at the Soonchunhyang University Hospital, were studied independently of their family histories. The age range was 18 to 40 with a median of 34.5 years. Lymphocyte specimens from peripheral blood were studied for the heterozygous mutations of BRCA1 and BRCA2 using direct sequencing methods. Immunohistochemistry was peformed on the paraffin-embedded tissue blocks that were available. Results: Eleven deleterious mutations (18.3%, 6 in BRCA1 and 5 in BRCA2) and 7 missense mutations of unknown significance (11.7%), were found among the 60 patients. More than half of the mutation were novel, and were not reported in the database. Most of the BRCA-associated patients had no history of breast cancer. No treatment related failures were observed in the BRCA carriers, with the exception of one patient that had experienced a new primary tumor of the contralateral breast. The seven year relapse free survival rate were 50 and 79% In the BRCA carrier and BRCA negative patients, respectively. Although the expression of estrogen and progesterone receptors were less common, and histological features more aggressive, in the BRCA associated tumors, the outcome of the patients with BRCA mutations was not poorer than that on the patients without deleterious mutations. Conclusion.: Despite the BRCA mutation carriers having adverse prognostic features, the recurrence rate was relatively lower than that in the BRCA non-carrying Korean patients wi4h early-onset breast carcinomas. In addition, although the prevalence of the BRCA mutation in Korean patients was higher than that in white patients, the penetrance of the cancer seemed to be relatively low in Korean women carrying BRCA mutations. A large population based study of the BRCA mutation, with a long-term follow-up of the study patients will be required to confirm these results.

• Journal of Genetic Medicine
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• v.9 no.1
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• pp.1-10
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• 2012

About 7% of all breast cancer (BC) cases result from a genetic predisposition, and approximately 1,000 patients develop hereditary BC (HBC) every year in Korea. BRCA1 and BRCA2 are the primary genes underlying HBC. The average cumulative risks in BRCA1 mutation carriers at 70 years of age are 65% (95% confidence interval 44-78%) for BC and 39% (18-54%) for ovarian cancer (OC). The corresponding estimates for BRCA2 are 45% (31-56%) and 11% (2.4-19%), respectively. The penetrance of BRCA mutations is not the same between patients and can depend on factors such as race and birth-cohort. The Korean Hereditary Breast Cancer (KOHBRA) study is a large prospective nationwide study that includes 39 participating centers. Between May 2007 and May 2010, the first phase of the KOHBRA study was planned and fulfilled successfully. The primary aim of phase I was to estimate the prevalence of BRCA1/2 mutations and OC among a high-risk group of patients with HBC and their families. According to data collected during phase I of the study, the prevalence and penetrance of BRCA mutations were comparable to corresponding data from Western countries. For the second phase of the KOHBRA study, we are currently investigating a Korean BRCA mutation prediction model, prognostic factors in BRCA-related BC, environmental/genetic modifiers, and implementing a genetic counseling network. The final goal of the KOHBRA study is to create clinical practice guidelines for HBC in Korea. In this article, I review the genetics of HBC, summarize the characteristics of Korean HBC, and discuss current and future HBC research in Korea.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.5
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• pp.2987-2990
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• 2013

Background: To explore mRNA expression and clinical significance of ERCC1, BRCA1, RRM1, TYMS and TUBB3 genes in tumor tissue of postoperative patients with non-small cell lung cancer (NSCLC). Materials and Methods: Sixty NSCLC patients undergoing radical operation in our hospital from Nov., 2011 to Jun., 2012 were selected. Plasmid standards of ERCC1, BRCA1, RRM1, TYMS and TUBB3 were established and standard curves were prepared by SYBR fluorescent real-time quantitative PCR analysis. Samples from tumor centers were taken to detect mRNA expression of ERCC1, BRCA1, RRM1, TYMS and TUBB3 genes in cancerous tissue during operation. The total mRNA expression quantities were compared according to different clinical characteristics. Results: The total expression quantities of 5 genotypes from high to low were ERCC1>RRM1>TUBB3>TYMS>BRCA1 in turn. By pairwise comparisons, other differences showed statistical significance (p<0.05 or p<0.01) except for TYMS and TUBB3 (p>0.05); the low expression rates from high to low were ERCC1>TYMS>TUBB3>TUBB3>RRM1>BRCA1 in turn. The expression quantities of BRCA1, RRM1 and TYMS in males, smokers and patients without adenocarcinoma were all significantly higher than that in females, non-smokers and patients with adenocarcinoma, and significant differences were present (p<0.05 or p<0.01). In terms of pathological staging, the expression quantities of BRCA1, RRM1 and TYMS in phases IIa~IIb and IIIa~IIIb had a tendency to be greater than in phases I and IV. Conclusions: Resistance to chemotherapy and sensitivity to targeted therapy differ among patients with NSCLC. Differences in gene expression in different individuals were also revealed. Only according to personalized detection results can individualized therapeutic regimens be worked out, which is a new direction for oncotherapy.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.6
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• pp.2973-2978
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• 2012

Background: Cancer stem cells (CSC) have been described in a variety of malignancies, including breast carcinomas. Among several markers, aldehyde dehydrogenase 1 (ALDH1) has been identified as reliable for breast cancer stem cells. Knockdown of BRCA1 in primary breast epithelial cells leads to an increase in cells expressing ALDH1. Methods: We examined 127 breast carcinomas for expression of ALDH1, using immunohistochemistry and correlated with clinicopathological parameters as well as the BRAC1 status. Results: Comparing the results for both ALDH1 and BRCA1 expression showed a significant inverse association between the two, indicating that reduced BRCA1 was more often seen in breast cancer cells expressing ALDH1 (p-value = 0.044). A total of 24/110 (22%) of tumours displayed the ALDH1 + / BRCA1 -/low phenotype, which showed a trend for a relation with a high grade (p-value= 0.056). Cytoplasmic expression of ALDH1 was not correlated with tumour characteristics. Conclusion: Taken together, our findings suggest that increased ALDH1 is inversely correlated with decreased BRCA1 in a series of unselected breast carcinomas. Therefore, ALDH1 positive (cancer stem) cells with reduced BRCA1 phenotype may indicate a subset of patients for whom specific targeting of the CSC marker ALDH1 and more aggressive adjuvant treatment is appropriate.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.10
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• pp.5671-5674
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• 2013

Incidence of breast cancer shows geographical variation, even within areas of ethnic homogeneity. Saudi Arabia has witnessed an increase in occurrence of breast cancer in its unexplored ethnic populations over the past few years. We aimed at determining whether any association exists between single nucleotide polymorphisms in breast cancer associated gene 1 (BRCA1) and breast cancer associated gene 2 (BRCA2) and the risk of breast cancer. TaqMan based Real Time Polymerase chain reaction genotyping assays were used to determine the frequency of single nucleotide polymorphisms in BRCA1 (rs799917) and BRCA2 (rs144848) in a group of 100 breast cancer patients and unaffected age matched controls of Saudi Arabian origin. The present data revealed that neither BRCA1 nor the BRCA2 studied variant show any significant association with the disease. This study failed to find any role of the concerned variants in breast cancer either as risk or as prognostic factors. The small number of patients registered was one of the limitations of this study. In summary, comparison of mutation profile with other ethnic populations and regions reflected both differences and similarities indicating co-exposure to a unique set of risk factors. The differences could be due to exposure to particular environmental carcinogens; different lifestyle, reproductive pattern; dietary or cultural practices of Saudi Arabian women that need further investigations.