Familial non-BRCA1/BRCA2-associated breast cancer

Breast cancer risk factors and mammographic density among 12518 average-risk women in rural China

BACKGROUND

Mammographic density (MD) is a strong risk factor for breast cancer. We aimed to evaluate the association between MD and breast cancer related risk factors among average-risk women in rural China.

METHODS

This is a population-based screening study. 12518 women aged 45-64 years with complete MD data from three maternal and childcare hospitals in China were included in the final analysis. ORs and 95%CIs were estimated using generalized logit model by comparing each higher MD (BI-RADS b, c, d) to the lowest group (BI-RADS a). The cumulative logistic regression model was used to estimate the ORtrend (95%CI) and Ptrend by treating MD as an ordinal variable.

RESULTS

Older age (ORtrend = 0.81, 95%CI: 0.79-0.81, per 2-year increase), higher BMI (ORtrend = 0.73, 95%CI: 0.71-0.75, per 2 kg/m2), more births (ORtrend = 0.47, 95%CI: 0.41-0.54, 3 + vs. 0-1), postmenopausal status (ORtrend = 0.42, 95%CI: 0.38-0.46) were associated with lower MD. For parous women, longer duration of breastfeeding was found to be associated with higher MD when adjusting for study site, age, BMI, and age of first full-term birth (ORtrend = 1.53, 95%CI: 1.27-1.85, 25 + months vs. no breastfeeding; ORtrend = 1.45, 95%CI: 1.20-1.75, 19-24 months vs. no breastfeeding), however, the association became non-significant when adjusting all covariates. Associations between examined risk factors and MD were similar in premenopausal and postmenopausal women except for level of education and oral hormone drug usage. Higher education was only found to be associated with an increased proportion of dense breasts in postmenopausal women (ORtrend = 1.08, 95%CI: 1.02-1.15). Premenopausal women who ever used oral hormone drug were less likely to have dense breasts, though the difference was marginally significant (OR = 0.54, P = 0.045). In postmenopausal women, we also found the proportion of dense breasts increased with age at menopause (ORtrend = 1.31, 95%CI: 1.21-1.43).

CONCLUSIONS

In Chinese women with average risk for breast cancer, we found MD was associated with age, BMI, menopausal status, lactation, and age at menopausal. This finding may help to understand the etiology of breast cancer and have implications for breast cancer prevention in China.

Factors for the Primary Prevention of Breast Cancer: A Meta-Analysis of Prospective Cohort Studies

Background: This report provided the effect of 15 preventable factors on the risk of breast cancer incidence.

Study design: A systematic review and meta-analysis.

Methods: A detailed research was conducted on PubMed, Web of Science, and Scopus databases in January 2020. Reference lists were also screened. Prospective cohort studies addressing the associations between breast cancer and 15 factors were analyzed. Between-study heterogeneity was investigated using the χ², τ², and I² statistics. The probability of publication bias was explored using the Begg and Egger tests and trim-and-fill analysis. Effect sizes were expressed as risk ratios (RRs) with 95% confidence intervals (CIs) using a random-effects model.

Results: Based on the results, out of 147,083 identified studies, 197 were eligible, including 19,413,702 participants. The RRs (95% CI) of factors associated with breast cancer were as follows: cigarette smoking 1.07 (1.05, 1.09); alcohol drinking 1.10 (1.07, 1.12); sufficient physical activity 0.90 (0.86, 0.95); overweight/obesity in premenopausal 0.92 (0.82, 1.03) and postmenopausal 1.18 (1.13, 1.24); nulliparity 1.16 (1.03, 1.31); late pregnancy 1.37 (1.25, 1.50); breastfeeding 0.87 (0.81, 0.93); ever using oral contraceptive 1.00 (0.96, 1.05); ever using estrogen 1.13 (1.04, 1.23); ever using progesterone 1.02 (0.84, 1.24); ever using estrogen/progesterone 1.60 (1.42, 1.80); ever taking hormone replacement therapy 1.26 (1.20, 1.32); red meat consumption 1.05 (1.00, 1.11); fruit/vegetable consumption 0.87 (0.83, 0.90); and history of radiation therapy, based on single study 1.31 (0.87, 1.98).

Conclusions: This meta-analysis provided a clear picture of several factors associated with the development of breast cancer. Moreover, the useful information in this study may be utilized for ranking and prioritizing preventable risk factors to implement effective prevention programs.

Changing practice: moving to a specialist nurse-led service for BRCA gene testing

Some 5–10% of all breast cancers are associated with a pathogenic variant in a breast cancer-associated gene (BRCA1/BRCA2). Historically, with referral to the Nottingham University Hospitals NHS Trust's clinical genetics department for genetic testing, waiting times were on average 12–14 weeks for an initial appointment and 4–6 months to obtain results from the date of testing. A specialist, nurse-led mainstreaming cancer genetics (MCG) service was set up in the trust's Nottingham Breast Institute (NBI) to: reduce waiting times for the initial consultation, counselling, consent and obtaining results for BRCA1/BRCA2 gene testing; and to ensure appropriate patients with breast cancer were offered genetic testing. Two breast clinical nurse specialists were trained so they could counsel, consent and give results for the BRCA1/BRCA2 gene testing directly to patients. Average waiting times for results from the time of testing were reduced to 35.8 days under the nurse-led service, which enabled oncologists and patients to consider individual treatment options at an earlier time. The MCG service reduced waiting times, resulting in an improved, more streamlined service for patients undergoing genetic testing. The MCG service extended the scope of practice of the breast nurse clinical specialists, embedded an expert advanced nursing role in the breast multidisciplinary team and developed nurse mentoring opportunities.

BRCA1 represses DNA replication initiation through antagonizing estrogen signaling and maintains genome stability in parallel with WEE1-MCM2 signaling during pregnancy

The mammary gland undergoes fast cell proliferation during early pregnancy, yet the mechanism to ensure genome integrity during this highly proliferative stage is largely unknown. We show that pregnancy triggers replicative stresses leading to genetic instability in mice carrying a mammary specific disruption of breast cancer associated gene-1 (BRCA1). The fast cell proliferation was correlated with enhanced expression of most genes encoding replisomes, which are positively regulated by estrogen/ERα signaling but negatively regulated by BRCA1. Our further analysis revealed two parallel signaling pathways, which are mediated by ATR-CHK1 and WEE1-MCM2 and are responsible for regulating DNA replication checkpoint. Upon DNA damage, BRCA1 deficiency markedly enhances DNA replication initiation and preferably impairs DNA replication checkpoint mediated by ATR and CHK1. Meanwhile, DNA damage also activates WEE1-MCM2 signaling, which inhibits DNA replication initiation and enables BRCA1-deficient cells to avoid further genomic instability. Finally, we demonstrated that overriding this defense by WEE1 inhibition in combination with cisplatin, which causes DNA damage, serves as a promising therapeutic approach for killing BRCA1-deficient cancer cells.

Comparison of clinical features and oncologic outcomes between familial non-hereditary and hereditary breast cancer in Korean female patients

BACKGROUND

The authors compared the clinical features between familial (non-hereditary) and hereditary breast cancer. And we also analyzed their oncologic outcomes to establish appropriate surveillance protocol for familial (non-hereditary) and hereditary breast cancer.

METHODS

Among 232 patients with breast cancer who were performed BRCA gene evaluation, twenty-eight patients were diagnosed as hereditary breast cancer with BRCA gene mutation and one-hundred and seventy-six patients were familial (non-hereditary) breast cancer. The clinical characteristics and oncologic outcomes were compared between two groups.

RESULTS

While the incidence of multifocality was higher in familial (non-hereditary) breast cancer group (p < 0.001), the bilaterality was higher in hereditary breast cancer group (p < 0.001). And the rate of pathologic complete remission was also significantly higher in hereditary breast cancer group (p = 0.030). The characteristics of tumor were different between familial (non-hereditary) breast cancer and hereditary breast cancer. The oncologic outcome was better in familial (non-hereditary) breast cancer group than hereditary breast cancer group except death.

CONCLUSION

The clinical characteristics of familial (non-hereditary) breast cancer were different from those of hereditary breast cancer but similar to those of sporadic breast cancer. The prognosis of the familial (non-hereditary) breast cancer was significantly better than hereditary breast cancer.

Transcriptome mining of non-BRCA1/A2 and BRCA1/A2 familial breast cancer

About 10% of all breast cancer cases are the familial type. Mutations in two highly penetrance breast cancer susceptibility genes, BRCA1 and BRCA2, can only explain 20% to 25% of genetic susceptibility to breast cancer, and most familial breast cancer cases have intact BRCA1 and BRCA2 genes that refer to non-BRCA1/A2 or BRCAX familial breast cancer. Despite extensive studies, more than 50% of genetic susceptibility to breast cancer remained to be disclosed. Finding the differences between these two types of breast cancer (non-BRCA1/A2 and BRCA1/A2) at genomic, transcriptomic, and proteomic levels can help us to elucidate fundamental molecular processes and develope more promising therapeutic targets. Here, we used expression data of 391 patients with familial breast cancer including 195 non-BRCA1/A2 and 196 BRCA1 and/or BRCA2 cases from four independent studies by means of meta-analysis to find differences in gene expression signature between these two types of familial breast cancer. As well as, we applied comprehensive network analysis to find crucial protein complexes and regulators for each condition. Our results revealed significant overexpression of cell cycle processes in BRCA1/A2 patients and significant overexpression of estrogen axis in non-BRCA1/A2 patients. Moreover, we found FOXM1 as the central regulator of cell cycle processes and GATA3, FOXA1, and ESR1 as the main regulators of estrogen axis.

Association between CYP17 T-34C rs743572 and breast cancer risk

Association between CYP17 T-34C (rs743572) polymorphism and breast cancer (BC) risk was controversial. In order to derive a more definitive conclusion, we performed this meta-analysis. We searched in the databases of PubMed, EMBASE and Cochrane for eligible publications. Pooled odds ratios (ORs) with 95% confidence intervals (95% CIs) were used to assess the strength of association between CYP17 T-34C polymorphism and breast cancer risk. Forty-nine studies involving 2,7104 cases and 3,4218 control subjects were included in this meta-analysis. In overall, no significant association between CYP17 T-34C polymorphism and breast cancer susceptibility was found among general populations. In the stratified analysis by ethnicity and source, significant associations were still not detected in all genetic models; besides, limiting the analysis to studies with controls in agreement with HWE, we also observed no association between CYP17 T-34C polymorphism and breast cancer risk. For premenopausal women, we didn't detect an association between rs743572 and breast cancer risk; however, among postmenopausal women, we observed that the association was statistically significant under the allele contrast genetic model (OR = 1.10, 95% CI = 1.03-1.17, P = 0.003), but not in other four models. In conclusion, rs743572 may increase breast cancer risk in postmenopausal individuals, but not in premenopausal folks and general populations.

Risk-benefit assessment of the combined oral contraceptive pill in women with a family history of female cancer

INTRODUCTION

Oral contraceptive pills (OCPs) are the most frequently used form of effective, reversible contraception among women of childbearing potential. In the average risk population, OCPs may offer a protective benefit against ovarian, endometrial and colorectal malignancies. In women at high risk for breast, ovarian, endometrial or colorectal malignancies, the risk-benefit profile is less well studied.

AREAS COVERED

In this article, we review pertinent literature on the use of OCPs in patients with genetic susceptibilities due to mutations in BRCA1, BRCA2 or mismatch repair genes implicated in hereditary nonpolyposis colorectal cancer as well as those with a strong family history of malignancies associated with these syndromes.

EXPERT OPINION

For women at high risk for ovarian, endometrial and/or colorectal malignancies due to genetic susceptibilities or a strong family history, the possibility of chemoprevention with OCPs may be an attractive option; however, the potential increase in breast cancer, although small, must be considered in clinical decision-making. The ultimate decision to use OCPs in a high-risk woman should be based on a consideration of her specific genetic risk, her age, her reproductive plans and her willingness to consider surgical prophylaxis options.

Drug repurposing screen identifies lestaurtinib amplifies the ability of the poly (ADP-ribose) polymerase 1 inhibitor AG14361 to kill breast cancer associated gene-1 mutant and wild type breast cancer cells

Introduction

Breast cancer is a devastating disease that results in approximately 40,000 deaths each year in the USA. Current drug screening and chemopreventatitive methods are suboptimal, due in part to the poor specificity of compounds for cancer cells. Poly (ADP-ribose) polymerase 1 (PARP1) inhibitor (PARPi)-mediated therapy is a promising approach for familial breast cancers caused by mutations of breast cancer-associated gene-1 and -2 (BRCA1/2), yet drug resistance frequently occurs during the treatment. Moreover, PARPis exhibit very little effect on cancers that are proficient for DNA repair and clinical efficacy for PARPis as single-agent therapies has yet to be illustrated.

Methods

Using a quantitative high-throughput screening approach, we screened a library containing 2,816 drugs, most of which are approved for human or animal use by the Food and Drug Administration (FDA) or other countries, to identify compounds that sensitize breast cancer cells to PARPi. After initial screening, we performed further cellular and molecular analysis on lestaurtinib, which is an orally bioavailable multikinase inhibitor and has been used in clinical trials for myeloproliferative disorders and acute myelogenous leukemia.

Results

Our study indicated that lestaurtinib is highly potent against breast cancers as a mono-treatment agent. It also strongly enhanced the activity of the potent PARPi AG14361 on breast cancer cell growth both in vitro and in vivo conditions. The inhibition of cancer growth is measured by increased apoptosis and reduced cell proliferation. Consistent with this, the treatment results in activation of caspase 3/7, and accumulation of cells in the G2 phase of the cell cycle, irrespective of their BRCA1 status. Finally, we demonstrated that AG14361 inhibits NF-κB signaling, which is further enhanced by lestaurtinib treatment.

Conclusions

Lestaurtinib amplifies the ability of the PARP1 inhibitor AG14361 to kill BRCA1 mutant and wild-type breast cancer cells, at least in part, by inhibiting NF-κB signaling. Each of these drugs has been approved for clinical trials for several different cancers, thus, their combination treatment should be applicable for a breast cancer trial in the future.

Prospective study of high-risk, BRCA1/2-mutation negative women: the 'negative study'

Background

We previously reported that women from high-risk families who tested negative for a BRCA1 or BRCA2 (BRCA1/2) mutation were four times more likely to develop breast cancer compared to women in the general population. Preventive measures and risk factors for breast cancer development in these high-risk women have not been evaluated to the same extent as BRCA1/2 positive women. Further, there is virtually no scientific evidence about best practices in their management and care. The proposed study will examine a role of genetic and non-genetic factors and develop the systems and parameters for the monitoring and surveillance necessary to help establish guidelines for the care of this high-risk population.

Methods/Design

To achieve our goals, we will assemble and follow a Canadian cohort of 1,000 cancer-free women with a strong family history breast cancer (defined as two or more relatives affected by breast cancer under the age of 50, or three or more relatives diagnosed with breast cancer at any age from one side of the family and with no BRCA1/2 mutation in the family). All eligible participants will be mailed a study package including invitation to participate, consent form, a research questionnaire to collect data regarding family history, reproductive and lifestyle factors, as well as screening and surgery. Usual dietary intake will be assessed by a diet history questionnaire. Biological samples including toenail clippings, urine and blood samples will be collected. These women will be followed every two years by questionnaire to update exposure information, screening practices, surgical and chemoprevention, and disease development.

Discussion

Findings from this study will serve to help establish clinical guidelines for the implementation of prevention, counseling, and treatment practices for women who face an elevated risk of breast cancer due to family history, but who do not carry a BRCA1/2 mutation.

Mouse models of BRCA1 and their application to breast cancer research

Germline mutations of human breast cancer-associated gene 1 (BRCA1) predispose women to breast and ovarian cancers. In mice, over 20 distinct mutations, including null, hypomorphic, isoform, conditional, and point mutations, have been created to study functions of Brca1 in mammary development and tumorigenesis. Analyses using these mutant mice have yielded an enormous amount of information that greatly facilitates our understanding of the gender- and tissue-specific tumor suppressor functions of BRCA1, as well as enriches our insights into applying these preclinical models of disease to breast cancer research. Here, we review features of these mutant mice and their applications to cancer prevention and therapeutic treatment.

A critical role of CD29 and CD49f in mediating metastasis for cancer-initiating cells isolated from a Brca1-associated mouse model of breast cancer

Cancer metastasis is a lethal problem that claims the lives of over 90% of cancer patients. In this study, we have investigated metastatic potential of cancer stem cells (CSCs) isolated from mammary tumors of a Brca1-mutant mouse model. Our data indicated that CSCs, which are enriched in CD24(+)CD29(+)/CD49f(+) cell population, displayed much higher migration ability than CD24(-)CD29(-)/CD49f(-) cells in tissue culture and enhanced metastatic potential in allograft-nude mice. CD24(+)CD29(+) cells maintained the ability to differentiate and reconstitute heterogeneity in the metastatic tumors whereas CD24(-)CD29(-) cells could not. Corresponding to their enhanced metastatic ability, CD24(+)CD29(+) cells exhibited features of the epithelial to mesenchymal transition. Finally, using short hairpin RNA to knock down CD29 and/or CD49f in metastatic cancer cells, we demonstrated that while acute knockdown of CD29 or CD49f alone slightly decreased cell migration ability, knockdown of both genes generated a profound effect to block their migration, revealing an overlapping, yet critical function of both genes in the migration of CSCs. Our findings indicate that in addition to serving as markers of CSCs, CD29 and CD49f may also serve as potential therapeutic targets for cancer metastasis.

Longer-term influence of breast cancer genetic counseling on cognitions and distress: smaller benefits for affected versus unaffected women

OBJECTIVE

To evaluate outcomes of breast cancer genetic counseling in women with and without breast cancer.

METHODS

Seventy-seven first-time attendees (n=44 affected) completed questionnaires assessing cognitions (risk accuracy, knowledge, perceived personal control [PPC]) and distress (state anxiety [STAI], cancer-related stress reactions [IES]) from immediately before to immediately and six months after completing counseling. Data were analyzed using multilevel repeated measures and trend analyses.

RESULTS

In affected counselees, mean cognitions did not significantly differ over time, anxiety significantly decreased, and IES levels were increased immediately post-counseling. In unaffected counselees, cognitions significantly improved over time except for knowledge. Distress levels showed similar patterns as in affected women. Improvements in cognitions and distress were significantly smaller in affected versus unaffected women.

CONCLUSION

Overall, counseling educates women about breast cancer risk and alleviates their anxiety. Importantly, benefits gained at immediate follow-up seem maintained over time.

PRACTICE IMPLICATION

Affected women seem to benefit less from counseling. Counselors may need to devote more effort into educating these women and addressing their anxieties. Future studies should confirm the unexpected finding that cancer-related distress increased immediately post-counseling.

Yin Yang 1 positively regulates BRCA1 and inhibits mammary cancer formation

Expression of the breast cancer-associated gene 1 (BRCA1) in sporadic breast cancers is usually reduced, yet the underlying mechanisms remains elusive. To identify factors that are responsible for reduced BRCA1 expression, we screened 92 known transcription factors for their ability to regulate expression of BRCA1. Among several potential regulators, the Gli-Krueppel-related transcription factor Yin Yang 1 (YY1) showed the most dramatic transactivation of the BRCA1 promoter. YY1 binds to the promoter of BRCA1, and its overexpression resulted in increased expression of BRCA1 and a number of BRCA1 downstream genes. We further showed that overexpression of YY1 in cancer cells inhibited cell proliferation, foci formation and tumor growth in nude mice. To assess the clinical relevance between YY1 and BRCA1, we studied expression of YY1 and BRCA1 from human breast cancer samples and tissue arrays, and detected a significant positive correlation between the level of YY1 and BRCA1 expression in these cancers. Taken together, these findings suggest that YY1 is a key regulator of BRCA1 expression and may be causally linked to the molecular etiology of human breast cancer.

Genetic risk, perceived risk, and cancer worry in daughters of breast cancer patients

This study explored relationships between worry, perceived risk for breast cancer, consulting a genetic counselor, having genetic testing, and genetic risk for women whose mothers had breast cancer. Analyses involved data from a community-based phone survey of women whose mothers had breast cancer. Participants were categorized as having low, intermediate, or high genetic risk based on their reported family history, in accordance with an accepted classification scheme. The Lerman Breast Cancer Worry Scale measured worry, and participants reported their perceived lifetime likelihood of breast cancer, risk compared to others, and chance from 1 to 100. ANOVA, chi-square, and multiple regression analyses were conducted as appropriate. One hundred-fifty women participated. Mean age was 38 years, and 81% were Caucasian. Fifty-two women had low, 74 had intermediate, and 24 had high genetic risk for breast cancer. There were no significant differences in worry or perceived risk by hereditary risk category. Most high-risk women (91%) had not spoken with a genetic counselor, and no one had previous genetic testing. These findings suggest perceived risk, worry about breast cancer, and use of expert consultation do not match the genetic contribution to risk. There is a need for effectively stratifying and communicating risk in the community and providing tailored reassurance or referral for high-risk assessment.

Interplay among BRCA1, SIRT1, and Survivin during BRCA1-associated tumorigenesis

Germline mutations of BRCA1 predispose women to breast and ovarian cancers. However, the downstream mediators of BRCA1 function in tumor suppression remain elusive. We found that human BRCA1-associated breast cancers have lower levels of SIRT1 than their normal controls. We further demonstrated that mammary tumors from Brca1 mutant mice have low levels of Sirt1 and high levels of Survivin, which is reversed by induced expression of Brca1. BRCA1 binds to the SIRT1 promoter and increases SIRT1 expression, which in turn inhibits Survivin by changing the epigenetic modification of histone H3. Absence of SIRT1 blocks the regulation of Survivin by BRCA1. Furthermore, we demonstrated that activation of Sirt1 and inhibition of Survivin expression by resveratrol elicit a more profound inhibitory effect on Brca1 mutant cancer cells than on Brca1-wild-type cancer cells both in vitro and in vivo. These findings suggest that resveratrol treatment serves as an excellent strategy for targeted therapy for BRCA1-associated breast cancer.

Identification and characterization of cancer initiating cells from BRCA1 related mammary tumors using markers for normal mammary stem cells

It is hypothesized that cancer stem cells arise either from normal stem cells or from progenitor cells that have gained the ability to self-renew. Here we determine whether mammary cancer stem cells can be isolated by using antibodies that have been used for the isolation of normal mammary stem cells. We show that BRCA1 mutant cancer cell lines contained a subpopulation of CD24+CD29+ or CD24+CD49f+ cells that exhibited increased proliferation and colony forming ability in vitro, and enhanced tumor-forming ability in vivo. The purified CD24+CD29+ cells could differentiate and reconstitute the heterogeneity found in parental cells when plated as a monolayer. Under low-attachment conditions, we detected "tumorspheres" only in the presence of double positive cells, which maintained their ability to self-renew. Furthermore, CD24+CD29+ cells could form tubular structures reminiscent of the mammary ductal tree when grown in three-dimensional cultures, implying that these cancer cells maintain some of the characteristics of the normal stem cells. Nevertheless, they could still drive tumor formation since as low as 500 double positive cells immediately after sorting from BRCA1 mutant primary tumors were able to form tumors with the same heterogeneity found in the original tumors. These data provide evidence that breast cancer stem cells originate from normal stem cells and advance our understanding of BRCA1-associated tumorigenesis with possible implications for future cancer treatment.

Prospective study of Outcomes in Sporadic versus Hereditary breast cancer (POSH): study protocol

Background

Young women presenting with breast cancer are more likely to have a genetic predisposition to the disease than breast cancer patients in general. A genetic predisposition is known to increase the risk of new primary breast (and other) cancers. It is unclear from the literature whether genetic status should be taken into consideration when planning adjuvant treatment in a young woman presenting with a first primary breast cancer. The primary aim of the POSH study is to establish whether genetic status influences the prognosis of primary breast cancer independently of known prognostic factors.

Methods/design

The study is a prospective cohort study recruiting 3,000 women aged 40 years or younger at breast cancer diagnosis; the recruiting period covers 1^st June 2001 to 31^st December 2007. Written informed consent is obtained at study entry. Family history and known epidemiological risk data are collected by questionnaire. Clinical information about diagnosis, treatment and clinical course is collected and blood is stored. Follow up data are collected annually after the first year. An additional recruitment category includes women aged 41 to 50 years who are found to be BRCA1 or BRCA2 gene carriers and were diagnosed with their first breast cancer during the study recruiting period.

Discussion

Power estimates were based on 10% of the cohort carrying a BRCA1 gene mutation. Preliminary BRCA1 and BRCA2 mutation analysis in a pilot set of study participants confirms we should have 97% power to detect a difference of 10% in event rates between gene carriers and sporadic young onset cases. Most of the recruited patients (>80%) receive an anthracycline containing adjuvant chemotherapy regimen making planned analyses more straightforward.

Genistein inhibits Brca1 mutant tumor growth through activation of DNA damage checkpoints, cell cycle arrest, and mitotic catastrophe

Epidemiological studies revealed that amount of consumption of soy was inversely related to incidence of breast cancer. Genistein, the predominant isoflavone in soy, has been reported to reduce the incidence of breast cancer in animal models. To investigate whether genistein has a therapeutic effect on BRCA1-associated breast cancer, we treated Brca1 mutant mammary tumor cells with genistein. We showed that genistein treatment depleted the G1 population of cells, which was accompanied by an accumulation of cells at G2. Some genistein-treated cells entered mitosis; however, they exhibited chromosome abnormalities and maintained tetraploidy owing to abortive mitotic exit. A fraction of G2 cells underwent endoreduplication and became polyploid, which was accompanied by increased cell death through activating DNA damage response. Furthermore, our data indicated that Brca1 mutant cells were more sensitive to genistein than some other types of cancer cells, highlighting a good therapeutic potential of genistein for BRCA1-associated breast cancer.

Contralateral recurrence and prognostic factors in familial non-BRCA1/2-associated breast cancer

BACKGROUND

A higher incidence of contralateral breast cancer and ipsilateral recurrence has been reported in familial breast cancer than in sporadic cancer. This study investigated the influence of contralateral cancer and tumour stage on survival in patients with familial non-BRCA1/BRCA2-associated breast cancer.

METHODS

The incidences of contralateral breast cancer, ipsilateral recurrence, distant disease-free and overall survival were assessed in 327 patients from families with three or more breast and/or ovarian cancers, but no BRCA1 or BRCA2 gene mutation (familial non-BRCA1/2), and in 327 control subjects with sporadic breast cancer, matched for year and age at detection.

RESULTS

Mean follow-up was 7.3 years for patients with familial-non-BRCA1/2 cancers and 6.5 years for patients with sporadic breast cancer. Tumours were stage T1 or lower in 62.1 per cent of familial non-BRCA1/2 cancers versus 49.9 per cent in sporadic breast cancers (P = 0.003), and node negative in 55.8 versus 52.1 per cent, respectively (P = 0.477). After 10 years the incidence of metachronous contralateral breast cancer was 6.4 per cent for familial non-BRCA1/2 tumours versus 5.4 per cent for sporadic cancers. The rate of ipsilateral recurrence was not significantly increased (17.0 versus 14.2 per cent, respectively, at 10 years; P = 0.132). Tumour size (hazard ratio (HR) 1.02 per mm increase, P = 0.016) and node status (HR 2.6 for three or more involved nodes versus node negative, P = 0.017) were independent predictors of overall survival in the familial non-BRCA1/2 group, and in the whole group, whereas contralateral breast cancer (HR 0.7, P = 0.503) and risk-reducing contralateral mastectomy (HR 0.4, P = 0.163) were not.

CONCLUSION

Stage at detection was a key determinant of prognosis in familial non-BRCA1/2 breast cancer, whereas contralateral cancer was not. Risk-reducing contralateral mastectomy did not significantly improve survival, but early detection can. Decisions on breast-conserving treatment can be made on the same grounds in patients with familial and sporadic breast cancer.

Familial and inherited breast cancers in Lower Silesia (Poland)

The purpose of this study was to determine the frequencies of hereditary and familial breast cancers among Lower Silesian women. The questionnaires, dealing with cancer episodes in first-and second-degree relatives, were sent to 5,000 females, who were diagnosed with breast cancer between 1984 and 2005. Twenty-five percent of the questionnaires were completed and returned. Their analysis and further counseling revealed that 24.9% of the responders met the criteria for familial breast cancer (FBC), including 10.5% definitive cases. Mutations in BRCA1 were detected in 32.5% and 1.9% of patients with definitive and suspected FBC, respectively. They all represented three of the abnormalities of the BRCA1 gene: 300T/G, 4153delA and 5382insC. No mutations of BRCA2 were found in material studied. Although a fraction of FBCs identified in our study was similar to those described in other European countries and in the United States, the percentages of genetic mutations seen on routine tests were relatively low. Consequently, the standardized analysis of oncological pedigree seems to be a more valuable diagnostic tool if patients with familial aggregations of breast cancer are targeted in a prophylactic context only.

PARP-1 inhibitors: are they the long-sought genetically specific drugs for BRCA1/2-associated breast cancers?

Recent studies demonstrated that PARP-1 [poly(ADP-ribose) polymerase-1] inhibitors kill breast cancer associated gene-1 and -2 (BRCA1/2) deficient cells with extremely high efficiency while BRCA+/- and BRCA+/+ cells are relatively non-responsive to the treatment. It was therefore proposed that PARP-1 inhibitors might be the long-sought genetically specific drugs that are both safe and effective for treating BRCA1/2-associated breast cancers. However, a report published in a recent issue of the International Journal of Biological Sciences revealed that PARP-1 inhibitors, although able to kill naïve BRCA1 mutant cells with high specificity both in vitro and in vivo, exhibit minimal specificity in inhibiting the growth of mouse mammary tumor cells irrespective of their BRCA1 status in allograft nude mice. Non-specific inhibition in human BRCA1+/+, BRCA1+/-, and BRCA1-/- breast cancer cells by PARP-1 inhibitors was also observed. Additional mutations occurring during cancer progression may be a culprit, although the exact cause for the resistance of BRCA1-/- breast cancer cells to PARP-1 inhibitors remains elusive. These findings suggest that PARP inhibition may serve as an approach for the prevention of BRCA related breast cancer and may be useful in combination with other chemotherapeutic agents in the treatment of breast cancer.

BRCA1: cell cycle checkpoint, genetic instability, DNA damage response and cancer evolution

Germline mutations of the breast cancer associated gene 1 (BRCA1) predispose women to breast and ovarian cancers. BRCA1 is a large protein with multiple functional domains and interacts with numerous proteins that are involved in many important biological processes/pathways. Mounting evidence indicates that BRCA1 is involved in all phases of the cell cycle and regulates orderly events during cell cycle progression. BRCA1 deficiency, consequently causes abnormalities in the S-phase checkpoint, the G(2)/M checkpoint, the spindle checkpoint and centrosome duplication. The genetic instability caused by BRCA1 deficiency, however, also triggers cellular responses to DNA damage that blocks cell proliferation and induces apoptosis. Thus BRCA1 mutant cells cannot develop further into full-grown tumors unless this cellular defense is broken. Functional analysis of BRCA1 in cell cycle checkpoints, genome integrity, DNA damage response (DDR) and tumor evolution should benefit our understanding of the mechanisms underlying BRCA1 associated tumorigenesis, as well as the development of therapeutic approaches for this lethal disease.