Immunohistochemical expression of BRCA2 protein and allelic loss at the BRCA2 locus in prostate cancer. CRC/BPG UK Familial Prostate Cancer Study Collaborators

A Case-Based Clinical Approach to the Investigation, Management and Screening of Families with BRCA2 Related Prostate Cancer

BRCA2 is the most commonly implicated DNA damage repair gene associated with inherited prostate cancer. BRCA2 deficient prostate cancer typically presents at a younger age, is more poorly differentiated, and is associated with worse survival outcomes than non-BRCA2 associated prostate cancer. Despite these unfavourable prognostic implications, poly-ADP ribose polymerase inhibitors and platinum-based chemotherapy have been identified as potent targeted therapeutic agents towards BRCA1/2 deficient cancer cells. This review article explores the literature surrounding BRCA2-related prostate cancer through a familial clinical scenario. The investigation, diagnosis and management of BRCA2 deficient prostate cancer will be explored, alongside the implications of the identification of a germline pathogenic BRCA2 variant within a family, cascade screening and prostate cancer surveillance in unaffected male BRCA2 carriers. A greater understanding of the molecular pathogenesis of DNA damage repair gene deficient prostate cancer, coupled with new treatment paradigms and widened access to both somatic and germline genetic analysis for prostate cancer patients and their families will hopefully enable the robust implementation of high quality evidence-based clinical pathways for both the management and identification of BRCA2 deficient prostate cancer and improved screening, early detection and prevention strategies for individuals at increased genetic risk of prostate cancer.

Immunohistochemical expression of BRCA1 and BRCA2 in a cohort of Ugandan men with prostate cancer: an analytical cross-sectional study

Background

Mutation of the tumour suppressor genes BRCA1 and BRCA2 is thought to cause early development of prostate cancer which has poor prognosis. The purpose of this study was to determine the expression of BRCA1/2 and correlate it with clinicopathological factors for patients with prostate cancer in uganda.

Methods

Retrospectively, we used immunohistochemistry to evaluate the expression of BRCA1/2 antibodies in tissue blocks of 188 patients with prostate cancer who were diagnosed between January 2005 and December 2014 in the Department of Pathology, Makerere College of Health Sciences. The Chi-Square test was used to determine the association of the categorical variables, whereas t-test was used to compare groups of mean of the variables in the study.

Results

Expression of BRCA1 and BRCA2 was found in 26.1% and 22.9% cases, respectively. Co-expression of BRCA1 and BRCA2 was found in only 7.4%. Gleason score was associated with expression of BRCA1 and BRCA2 (P = 0.013, P = 0.041, respectively). Age was not associated with BRCA1 and BRCA2 expression; P = 0.543, P = 0.091, respectively. Likewise, PSA was not associated with BRCA1 and BRCA2 expression; P = 0.446, P = 0.399, respectively.

Conclusion

BRCA1 and BRCA2 proteins in this study were expressed more in cases with poorly differentiated prostate cancer than in cases with either well or moderately differentiated prostate cancer. Co-expression of BRCA1 and BRCA2 proteins in the same patient in our study was 3 times less than either BRCA1 or BRCA2 alone.

Downregulation of APRIN expression increases cancer cell proliferation via an interleukin-6/STAT3/cyclin D axis

APRIN is a putative tumor suppressor whose expression is low in a variety of cancer cells. While decreased expression of APRIN leads to increased cell proliferation, unfavorable diagnosis or metastases in various cancer types, there is limited knowledge on the cellular mechanism of APRIN in cellular responses. The effect of APRIN depletion on cancer cell proliferation was examined in the present study, and the IL-6/STAT3/cyclin D axis was identified as a novel regulatory mechanism. Stable depletion of APRIN in cancer cells resulted in increased cell proliferation. Cytokine array analysis of the cells revealed that downregulation of APRIN induced secretion of interleukin-6 (IL-6) with corresponding activation of STAT3, a downstream intracellular mediator. Levels of cyclin D1 were increased in cells with APRIN depletion and cyclin D1 expression was associated with increased STAT3 binding on cyclin D1 promoter sequence; assessed by chromatin immunoprecipitation assay. The addition of an IL-6 neutralizing antibody P620 to the cell culture attenuated STAT3 activation and cyclin D1 expression in APRIN-depleted cells with corresponding decrease in cell proliferation. These experiments suggest that APRIN regulates cancer cell proliferation via an IL-6/STAT3/cyclin D axis and that targeting this axis in APRIN-associated cancer might provide a novel therapeutic approach.

The association of BRCA1 and BRCA2 mutations with prostate cancer risk, frequency, and mortality: A meta-analysis

BACKGROUND

A prior meta-analysis found no association between BRCA1 mutation and prostate cancer (PCa). Subsequent BRCA2 mutation studies have shown an association with PCa risk and mortality. We conducted a meta-analysis of overall BRCA mutation carriers and in subgroups to (1) estimate PCa risk in BRCA mutation carriers, (2) evaluate the frequency of BRCA mutation carriers in patients with PCa, and (3) compare cancer-specific survival (CSS) and overall survival (OS) among BRCA mutation carriers and noncarriers.

METHODS

We searched the PubMed/MEDLINE, Embase, and Cochrane databases. Unadjusted odds ratio (OR), percentage (%), and hazard ratio (HR) were used to calculate pooled estimates for PCa risk, frequency, and survival, respectively. Subgroup analyses by mutation type ( BRCA1 or BRCA2) were conducted for the three objectives. Further subgroup analyses by study design (age-sex-adjusted or crude), ascertainment method (ascertained or inferred genotyping), population (Ashkenazi Jewish or general population), and survival outcomes (CSS or OS) were conducted. The associations were evaluated using random-effects models, in two-sided statistical tests.

RESULTS

A total of 8 cohort, 7 case-control, 4 case-series, 28 frequency, and 11 survival studies were included. Being a BRCA mutation carrier ( BRCA1 and/or BRCA2) was associated with a significant increase in PCa risk (OR = 1.90, 95% CI = 1.58-2.29), with BRCA2 mutation being associated with a greater risk of PCa (OR = 2.64, 95% CI = 2.03-3.47) than BRCA1 (OR = 1.35, 95% CI = 1.03-1.76). The frequency of BRCA1 and BRCA2 carriers in patients with PCa was 0.9% and 2.2%, respectively. OS (HR = 2.21, 95% CI = 1.64-2.30) and CSS (HR = 2.63, 95% CI = 2.00-3.45) were significantly worse among BRCA2 carriers compared to noncarriers, whereas OS (HR = 0.47, 95% CI = 0.11-1.99) and CSS (HR = 1.07, 95% CI = 0.38-2.96) were statistically not significant when comparing BRCA1 carriers and noncarriers.

CONCLUSIONS

There is a 1.90-fold greater risk of PCa in overall BRCA mutation carriers. This elevated PCa risk is attributable mainly to a 2.64-fold greater risk of PCa in BRCA2 carriers compared to a moderate 1.35-fold greater risk in BRCA1 carriers. The frequency of BRCA2 mutations was higher than BRCA1 mutations among patients with PCa. BRCA2 but not BRCA1 mutations were associated with higher PCa mortality. The BRCA mutation may be a clinical factor to stratify high-risk patients and guide clinical strategies for more effective treatments for patients with PCa.

BRCA2 mutations should be screened early and routinely as markers of poor prognosis: evidence from 8,988 patients with prostate cancer

The aim of this study was to focus on clinicopathological characteristics and prognosis in men with prostate cancer (PCa) harboring a breast cancer 2 (BRCA2) gene mutation and to offer convincing evidence to consider BRCA2 mutation as a marker of poor prognosis in the molecular classification of PCa. We searched relevant articles from PubMed, Embase, Web of Science, and the Cochrane Library databases to evaluate the differences in the overall survival (OS) and cancer-specific survival (CSS) between BRCA2 mutation carriers and non-carriers in patients with PCa. We included 525 BRCA2 mutation-carriers and 8,463 non-carriers in total from 10 studies in our meta-analysis. The results showed that carrying a BRCA2 mutation was correlated with a reduced CSS and OS when compared with that of non-carriers, with pooled Hazard Ratios (HRs) of 2.53 (95% confidence interval (CI): 2.10–3.06, P < 0.001) and 2.21 (95% CI: 1.64–2.99, P < 0.001), respectively. The results also demonstrated that BRCA2 mutation-carriers harbored a higher Gleason Score (GS) (> 7), TNM stage (> T3, N1, M1), and risk level than non-carriers. Our meta-analysis showed that a BRCA2 mutation predicted poor survival outcomes in patients with prostate cancer, especially in those undergoing treatments with radiotherapy. Therefore, the use of BRCA2 mutation as a clinical prognostic factor could help stratify the high-risk patients and provide clinical strategies for more effective targeted treatments for patients with prostate cancer.

Mutations in BRCA2 and taxane resistance in prostate cancer

Mutations in BRCA1 or BRCA2 define a subset of prostate cancer patients. Herein, we address the question whether BRCA1/2 mutations have a predictive impact on chemotherapy with docetaxel, a widely used drug in patients with metastatic castration resistant prostate cancer (mCRPC). Fifty-three men treated with docetaxel for mCRPC were tested for somatic BRCA1/2 mutations of the primary tumor. In a subgroup of patients, BRCA1/2 protein expression was tested as a potential surrogate marker for BRCA1/2 inactivation. Eight of 53 patients (15.1%) harbored a deleterious BRCA2 mutation. No BRCA1 mutation was found. Patients with a BRCA2 mutation showed a response rate of 25% to docetaxel in comparison to 71.1% in men with wildtype BRCA2 (p = 0.019). While the time to develop castration resistance was similar in both subgroups, the overall survival was significantly shorter in patients harboring a BRCA2 mutation. No correlation between the BRCA1/2 protein expression and the response to docetaxel was found. While the presence of a BRCA2 mutation does not preclude a response to docetaxel, there is overall a significant correlation between BRCA2 inactivation and a poor response rate. Our results suggest that a close oncological monitoring of patients with BRCA2 mutations for taxane resistance is warranted.

The zebrafish kidney mutant zeppelin reveals that brca2/fancd1 is essential for pronephros development

The zebrafish kidney is conserved with other vertebrates, making it an excellent genetic model to study renal development. The kidney collects metabolic waste using a blood filter with specialized epithelial cells known as podocytes. Podocyte formation is poorly understood but relevant to many kidney diseases, as podocyte injury leads to progressive scarring and organ failure. zeppelin (zep) was isolated in a forward screen for kidney mutants and identified as a homozygous recessive lethal allele that causes reduced podocyte numbers, deficient filtration, and fluid imbalance. Interestingly, zep mutants had a larger interrenal gland, the teleostean counterpart of the mammalian adrenal gland, which suggested a fate switch with the related podocyte lineage since cell proliferation and cell death were unchanged within the shared progenitor field from which these two identities arise. Cloning of zep by whole genome sequencing (WGS) identified a splicing mutation in breast cancer 2, early onset (brca2)/fancd1, which was confirmed by sequencing of individual fish. Several independent brca2 morpholinos (MOs) phenocopied zep, causing edema, reduced podocyte number, and increased interrenal cell number. Complementation analysis between zep and brca2^ZM_00057434 -/- zebrafish, which have an insertional mutation, revealed that the interrenal lineage was expanded. Importantly, overexpression of brca2 rescued podocyte formation in zep mutants, providing critical evidence that the brca2 lesion encoded by zep specifically disrupts the balance of nephrogenesis. Taken together, these data suggest for the first time that brca2/fancd1 is essential for vertebrate kidney ontogeny. Thus, our findings impart novel insights into the genetic components that impact renal development, and because BRCA2/FANCD1 mutations in humans cause Fanconi anemia and several common cancers, this work has identified a new zebrafish model to further study brca2/fancd1 in disease.

Intracellular location of BRCA2 protein expression and prostate cancer progression in the Swedish Watchful Waiting Cohort

Prostate cancer patients with inherited BRCA2 mutations have a survival disadvantage. However, it is unknown whether progression is associated with BRCA2 protein expression in diagnostic prostate cancer tissue, among men without inherited mutations. We conducted a nested case-control study within the Swedish Watchful Waiting cohort. The case group included all 71 patients who died from prostate cancer within 5 years from diagnosis and controls were all patients (n = 165) who lived at least 7 years after diagnosis. Tissue microarrays were stained using antibodies for C- and N-terminal domains of the BRCA2 protein. Location (nuclear, cytoplasmic and membranous) and magnitude (intensity and percentage) of expression were assessed. Logistic regression models produced odds ratios (OR) and 95% confidence intervals (CI) adjusted for age, year of diagnosis and Gleason score. Positive BRCA2 staining at the cell membrane was associated with reduced risk of death within 5 years (N-terminal: OR = 0.47, 95% CI = 0.21-1.04, P = 0.06; C-terminal: OR = 0.41, 95% CI = 0.18-0.91, P = 0.03) and low Gleason scores (P = 0.006). Positive cytoplasmic C-terminal staining was associated with higher Gleason scores and increased lethality (OR = 3.61, 95% CI = 1.61-8.07, P = 0.002). BRCA2 protein expression at the cell membrane and lack of C-terminal expression in the cytoplasm were associated with a reduced risk of rapidly fatal prostate cancer. BRCA2 protein expression in prostate cancer tissue may have independent prognostic value. The potential biological significance of BRCA2 expression at the cell membrane warrants further investigation.

Predicting high risk disease using serum and DNA biomarkers

PURPOSE OF REVIEW

To explore several serum and genetic-based biomarkers that may prove useful in following men being managed with active surveillance for localized prostate cancer by predicting those that either have the potential to develop, or already harbor occult high grade disease.

RECENT FINDINGS

There is increasing evidence that serum biomarkers human Kallikrein 2, early prostate cancer antigen, urokinase-type plasminogen activator/urokinase-type plasminogen activator receptor, transforming growth factor-β1 and interleukin-6/interleukin-6 receptor and genetic biomarkers BRCA1 and BRCA2, Phosphatase and tensin homolog, cellular myelocytomatosis oncogene and NKX3.1 may predict for aggressive high grade disease and are identifiable early in prostate carcinogenesis.

SUMMARY

One of the barriers of widespread adoption of active surveillance for low risk, localized prostate cancer is the concern that some patients may harbor occult high-risk disease at diagnosis, or develop more aggressive/noncurable disease not detected by our current well established prognostic factors. This review examines several serum and genetic-based biomarkers that appear to be of value in localized prostate cancer, unlike the vast majority of more established prostate cancer biomarkers that have been validated in far more advanced disease. Although the biomarkers discussed show exciting promise, their clinical utility is unknown, and their role in the active surveillance scenario needs further study.

APRIN is a cell cycle specific BRCA2-interacting protein required for genome integrity and a predictor of outcome after chemotherapy in breast cancer

Mutations in BRCA2 confer an increased risk of cancer development, at least in part because the BRCA2 protein is required for the maintenance of genomic integrity. Here, we use proteomic profiling to identify APRIN (PDS5B), a cohesion-associated protein, as a BRCA2-associated protein. After exposure of cells to hydroxyurea or aphidicolin, APRIN and other cohesin components associate with BRCA2 in early S-phase. We demonstrate that APRIN expression is required for the normal response to DNA-damaging agents, the nuclear localisation of RAD51 and BRCA2 and efficient homologous recombination. The clinical significance of these findings is indicated by the observation that the BRCA2/APRIN interaction is compromised by BRCA2 missense variants of previously unknown significance and that APRIN expression levels are associated with histological grade in breast cancer and the outcome of breast cancer patients treated with DNA-damaging chemotherapy.

BRCA2 is a moderate penetrance gene contributing to young-onset prostate cancer: implications for genetic testing in prostate cancer patients

BACKGROUND

A family history of prostate cancer (PrCa) is a strong risk factor for the disease, indicating that inherited factors are important in this disease. We previously estimated that about 2% of PrCa cases diagnosed ≤ 55 years harbour a BRCA2 mutation and PrCa among BRCA2 carriers has been shown to be more aggressive, with poorer survival.

METHODS

To further evaluate the role of BRCA2 in PrCa predisposition, we screened 1864 men with PrCa aged between 36 and 88 years. We analysed the BRCA2 gene using a novel high-throughput multiplex fluorescence heteroduplex detection system developed for the ABI3130xl genetic analyzer.

RESULTS

We identified 19 protein-truncating mutations, 3 in-frame deletions and 69 missense variants of uncertain significance (UV) in our sample set. All the carriers of truncating mutations developed PrCa at ≤ 65 years, with a prevalence of BRCA2 mutation of 1.20% for cases in this age group.

CONCLUSION

Based on the estimated frequency of BRCA2 mutations in the United Kingdom we estimate that germline mutations in the BRCA2 gene confer an ∼ 8.6-fold increased risk of PrCa by age 65, corresponding to an absolute risk of ∼ 15% by age 65. These results suggest that routine testing of early onset PrCa cases for germline BRCA2 mutations will further help to refine the prevalence and risk associated with BRCA2 mutations and may be useful for guiding management options.

Skp2 overexpression is associated with loss of BRCA2 protein in human prostate cancer

BRCA2 (breast cancer 2, early onset) is a tumor suppressor gene that confers increased susceptibility for prostate cancer (PCa). Previous in vitro experiments demonstrated that Skp2, an E3 ubiquitin ligase aberrantly overexpressed in PCa, is involved in the proteolytic degradation of BRCA2 in PCa cells, suggesting that the BRCA2-Skp2 interaction may play a role in prostate tumorigenesis. Herein, we investigated BRCA2 and Skp2 expression during PCa development using a prostate TMA. Although luminal and basal benign prostate epithelium exhibited moderate to strong nuclear BRCA2 immunostaining, the intensity and number of positive nuclei decreased significantly in high-grade prostatic intraepithelial neoplasia and PCa. Decreased frequency and intensity of nuclear BRCA2 labeling were inversely correlated with Skp2 expression in high-grade prostatic intraepithelial neoplasia and PCa. To functionally assess the effects of BRCA2 and Skp2 expression on prostate malignant transformation, we overexpressed Skp2 in normal immortalized prostate cells. Skp2 overexpression reduced BRCA2 protein and promoted cell growth and migration. A similar phenotype was observed after reduction of BRCA2 protein levels using specific BRCA2 small-interfering RNA. Forced BRCA2 expression in Skp2-overexpressing stable transfectants inhibited the migratory and growth properties by >60%. These results show that loss of BRCA2 expression during prostate tumor development is strongly correlated with both migratory behavior and cancer growth and include Skp2 as a BRCA2 proteolytic partner in vivo.

Prostate cancer in BRCA2 germline mutation carriers is associated with poorer prognosis

Background:

The germline BRCA2 mutation is associated with increased prostate cancer (PrCa) risk. We have assessed survival in young PrCa cases with a germline mutation in BRCA2 and investigated loss of heterozygosity at BRCA2 in their tumours.

Methods:

Two cohorts were compared: one was a group with young-onset PrCa, tested for germline BRCA2 mutations (6 of 263 cases had a germline BRAC2 mutation), and the second was a validation set consisting of a clinical set from Manchester of known BRCA2 mutuation carriers (15 cases) with PrCa. Survival data were compared with a control series of patients in a single clinic as determined by Kaplan–Meier estimates. Loss of heterozygosity was tested for in the DNA of tumour tissue of the young-onset group by typing four microsatellite markers that flanked the BRCA2 gene, followed by sequencing.

Results:

Median survival of all PrCa cases with a germline BRCA2 mutation was shorter at 4.8 years than was survival in controls at 8.5 years (P=0.002). Loss of heterozygosity was found in the majority of tumours of BRCA2 mutation carriers. Multivariate analysis confirmed that the poorer survival of PrCa in BRCA2 mutation carriers is associated with the germline BRCA2 mutation per se.

Conclusion:

BRCA2 germline mutation is an independent prognostic factor for survival in PrCa. Such patients should not be managed with active surveillance as they have more aggressive disease.

Loss of heterozygosity at the BRCA2 locus detected by multiplex ligation-dependent probe amplification is common in prostate cancers from men with a germline BRCA2 mutation

PURPOSE

Prostate cancer risk is increased for men carrying a pathogenic germline mutation in BRCA2, and perhaps BRCA1. Our primary aim was to test for loss of heterozygosity (LOH) at the locus of the mutation in prostate cancers from men who a carry pathogenic germline mutation in BRCA1 or BRCA2, and to assess clinical and pathologic features of these tumors.

EXPERIMENTAL DESIGN

From 1,243 kConFab families: (a) 215 families carried a pathogenic BRCA1 mutation, whereas 188 families carried a pathogenic BRCA2 mutation; (b) of the 158 men diagnosed with prostate cancer (from 137 families), 8 were confirmed to carry the family-specific BRCA1 mutation, whereas 20 were confirmed to carry the family-specific BRCA2 mutation; and (c) 10 cases were eliminated from analysis because no archival material was available. The final cohort comprised 4 and 14 men with a BRCA1 and BRCA2 mutation, respectively. We examined LOH at the BRCA1 and BRCA2 genes using multiplex ligation-dependent probe amplification of DNA from microdissected tumor.

RESULTS

LOH at BRCA2 was observed in 10 of 14 tumors from BRCA2 mutation carriers (71%), whereas no LOH at BRCA1 was observed in four tumors from BRCA1 mutation carriers (P = 0.02). Under the assumption that LOH occurs only because the cancer was caused by the germline mutation, carriers of BRCA2 mutations are at 3.5-fold (95% confidence interval, 1.8-12) increased risk of prostate cancer. A high Gleason was the only distinct clinical feature.

CONCLUSIONS

These observations are consistent with the idea that BRCA2, but not BRCA1, is a tumor suppressor of prostate cancer.

Prostate cancer in male BRCA1 and BRCA2 mutation carriers has a more aggressive phenotype

There is a high and rising prevalence of prostate cancer (PRCA) within the male population of the United Kingdom. Although the relative risk of PRCA is higher in male BRCA2 and BRCA1 mutation carriers, the histological characteristics of this malignancy in these groups have not been clearly defined. We present the histopathological findings in the first UK series of BRCA1 and BRCA2 mutation carriers with PRCA. The archived histopathological tissue sections of 20 BRCA1/2 mutation carriers with PRCA were collected from histopathology laboratories in England, Ireland and Scotland. The cases were matched to a control group by age, stage and serum PSA level of PRCA cases diagnosed in the general population. Following histopathological evaluation and re-grading according to current conventional criteria, Gleason scores of PRCA developed by BRCA1/2 mutation carriers were identified to be significantly higher (Gleason scores 8, 9 or 10, P=0.012) than those in the control group. Since BRCA1/2 mutation carrier status is associated with more aggressive disease, it is a prognostic factor for PRCA outcome. Targeting screening to this population may detect disease at an earlier clinical stage which may therefore be beneficial.

APRIN is a unique Pds5 paralog with features of a chromatin regulator in hormonal differentiation

Activation of steroid receptors results in global changes of gene expression patterns. Recent studies showed that steroid receptors control only a portion of their target genes directly, by promoter binding. The majority of the changes are indirect, through chromatin rearrangements. The mediators that relay the hormonal signals to large-scale chromatin changes are, however, unknown. We report here that APRIN, a novel hormone-induced nuclear phosphoprotein has the characteristics of a chromatin regulator and may link endocrine pathways to chromatin. We showed earlier that APRIN is involved in the hormonal regulation of proliferative arrest in cancer cells. To investigate its function we cloned and characterized APRIN orthologs and performed homology and expression studies. APRIN is a paralog of the cohesin-associated Pds5 gene lineage and arose by gene-duplication in early vertebrates. The conservation and domain differences we found suggest, however, that APRIN acquired novel chromatin-related functions (e.g. the HMG-like domains in APRIN, the hallmarks of chromatin regulators, are absent in the Pds5 family). Our results suggest that in interphase nuclei APRIN localizes in the euchromatin/heterochromatin interface and we also identified its DNA-binding and nuclear import signal domains. The results indicate that APRIN, in addition to its Pds5 similarity, has the features and localization of a hormone-induced chromatin regulator.

Prostate cancer progression and survival in BRCA2 mutation carriers

BACKGROUND

Mutations in the BRCA2 gene are associated with an increased risk of prostate cancer, but it is not known whether they are associated with progression of the disease. We compared prostate cancer-specific survival, disease stage, and tumor grade between prostate cancer patients carrying the Icelandic BRCA2 999del5 founder mutation and noncarriers.

METHODS

Using population-based registries, we identified all 596 prostate cancer patients who were diagnosed in Iceland during 1955 through 2004 among 29603 male relatives of unselected breast cancer probands. BRCA2 mutation status could be determined for 527 patients (88.4%). Stage and grade were abstracted from original records, blindly with respect to mutation status, for a subgroup of 89 patients that included all mutation carriers and, for each carrier, two control patients without the BRCA2 999del5 mutation who were matched to the carrier on years of diagnosis and birth. Hazard ratios (HRs) and 95% confidence intervals (CIs) for prostate cancer-specific survival were estimated using multivariable regression models. All statistical tests were two-sided.

RESULTS

The mutation was carried by 30 patients (5.7%). Compared with noncarriers, BRCA2 999del5 mutation carriers had a lower mean age at diagnosis (69.0 years versus 74.0 years; P = .002), more advanced tumor stage (stages 3 or 4, 79.3% versus 38.6%; P < .001), higher tumor grade (grades G3-4, 84.0% versus 52.7%, P = .007), and shorter median survival time (2.1 years, 95% CI = 1.4 to 3.6 years, versus 12.4 years, 95% CI = 9.9 to 19.7 years). Carrying the BRCA2 999del5 mutation was also associated with an increased risk of dying from prostate cancer (adjusting for year of diagnosis and birth, HR = 3.42, 95% CI = 2.12 to 5.51); the association remained after adjustment for stage and grade (HR = 2.35, 95% CI = 1.08 to 5.11). The prognosis of BRCA2 999del5 mutation carriers was not associated with period of diagnosis or with relatedness to breast cancer probands.

CONCLUSIONS

The Icelandic BRCA2 999del5 founder mutation was strongly associated with rapidly progressing lethal prostate cancer.

Two percent of men with early-onset prostate cancer harbor germline mutations in the BRCA2 gene

Studies of families with breast cancer have indicated that male carriers of BRCA2 mutations are at increased risk of prostate cancer, particularly at an early age. To evaluate the contribution of BRCA2 mutations to early-onset prostate cancer, we screened the complete coding sequence of BRCA2 for germline mutations, in 263 men with diagnoses of prostate cancer who were Collapse

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MESH Headings

• Adult
• Age of Onset
• Aged
• Base Sequence
• Breast Neoplasms/genetics
• DNA Mutational Analysis
• Female
• Genes, BRCA2
• Genetic Predisposition to Disease/genetics
• Genetic Testing
• Germ-Line Mutation/genetics
• Heterozygote
• Humans
• Male
• Middle Aged
• Ovarian Neoplasms/genetics
• Pedigree
• Polymorphism, Genetic/genetics
• Prostatic Neoplasms/genetics

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Molecular markers for predicting prostate cancer stage and survival

OBJECTIVE

To assess several molecular markers (detected by immunohistochemistry, IHC) to determine whether they can be used to improve the prognostic value of histological grade alone in predicting the behaviour of prostate cancer.

PATIENTS AND METHODS

Tumour tissue was retrieved from 156 men in whom tumour grade, stage and survival were known. The outcome measures were: (i) local stage (T-stage, organ-confined vs extraprostatic); (ii) metastatic status (M-stage, bone metastasis vs no bone metastasis); and (iii) survival. The IHC markers used were chosen to provide a broad representation of various aspects of tumour biology, i.e. the androgen receptor (AR) and oestrogen receptor (ER), adhesion molecules (E-cadherin), proliferation markers (MIB-1), tumour-suppressor genes (TP53 and the retinoblastoma gene product, Rb) and other novel cancer-related proteins (cyclin D1 and the breast cancer susceptibility gene product, BRCA2). All factors were assessed using logistic regression and Cox proportional-hazards survival models for predictive value, after adjusting for effects.

RESULTS

MIB-1, ER, cyclin D1 and E-cadherin all showed close statistically significant univariate associations with histological grade. Univariate analysis also identified close statistically significant associations between T-stage and both MIB-1 and E-cadherin. Likewise, there were close univariate associations for both M-stage and survival, and MIB-1, cyclin D1 and ER. Logistic regression modelling identified MIB-1, cyclin D1 and ER as statistically significant predictors of M-stage and, once MIB-1 was entered into the model, the effects of grade no longer made a significant contribution. MIB-1 was a significant predictor for T-stage, but the effects of grade remained significant in this model. Cox proportional-hazards modelling identified MIB-1, cyclin D1 and ER as being statistically significant predictors of survival, after adjusting for grade. After adjusting for both grade and MIB-1, the effects of cyclin D1 and ER were no longer statistically significant. Excess MIB-1, cyclin D1 or ER expression tended to be present within the most poorly differentiated and advanced-stage lesions; this provides an inherent instability to the models described. TP53, Rb, AR and BRCA2 were of limited prognostic value.

CONCLUSIONS

MIB-1, ER and cyclin D1 provide prognostic information that is clearly independent of grade. However, their true clinical value is probably limited because they are expressed mainly in the most advanced lesions. Nevertheless, MIB-1 expression is of sufficient value to warrant inclusion in future prognostic models. Furthermore, the expression of cyclin D1 and ER may reflect aspects of tumour biology that individually are worthy of further investigation. However, none of the IHC markers used in this study can be recommended for use in routine histological preparations.

Altered expression of BRCA1, BRCA2, and a newly identified BRCA2 exon 12 deletion variant in malignant human ovarian, prostate, and breast cancer cell lines

Germline mutations of BRCA1 and BRCA2 predispose to hereditary breast, ovarian, and possibly prostate cancer, yet structural mutations in these genes are infrequent in sporadic cancer cases. To better define the involvement of these genes in sporadic cancers, we characterized expression levels of BRCA1 and BRCA2 transcripts in cancer cell lines derived from neoplasms of the ovary, prostate, and breast and compared them with those expressed in primary cultures of normal epithelial cells established from these organs. We observed upregulation of BRCA1 and/or BRCA2 expression in six of seven ovarian cancer cell lines (OVCA420, OVCA429, OVCA432, ALST, DOV13, and SKOV3) when compared with levels found in normal ovary surface epithelial cells. Furthermore, five cancerous or immortalized prostatic epithelial cell lines (BPH-1, TSU-Pr1, LNCaP, PC-3, and DU145) also expressed higher levels of BRCA1 and/or BRCA2 mRNA than did primary cultures of normal prostatic epithelial cells. In contrast, only the estrogen receptor-positive MCF-7 cell line overexpressed these messages, whereas the estrogen receptor-negative breast cancer cell lines Hs578T, MDA-MB-231, and MDA-MB-468 showed no change in expression levels when compared with normal breast epithelial cells. In addition, expanding on our recent identification of a novel BRCA2 transcript variant carrying an in-frame exon 12 deletion (BRCA2 delta 12), we report increased expression of this variant in several ovarian, prostate, and mammary cancer cell lines (OVCA420, OVCA433, ALST, DOV13, SKOV3, TSU-Pr1, DU145, and MDA-MB-468). Most notably, high levels of BRCA2 delta 12 mRNA were detected in an estrogen receptor-positive breast cancer cell line, MCF-7, and in an androgen-independent prostate cancer cell line, DU-145. Interestingly, the wild-type BRCA2 transcript was barely detectable in DU145, which could be used as a model system for future investigations on BRCA2 delta 12 function. Taken together, our data suggest disruption of BRCA1 and/or BRCA2 gene expression in certain epithelial cancer cell lines of the ovary, prostate, and breast. Because wild-type BRCA1 and BRCA2 gene products increase during cell-cycle progression and are believed to exert growth-inhibitory action, enhanced expression of these genes in cancer cells may represent a negative feedback mechanism for curbing proliferation in fast-growing cells. At present, the functionality of BRCA2 delta 12 remains elusive.