Truncating BRCA1 Mutations Are Uncommon in a Cohort of Hereditary Prostate Cancer Families with Evidence of Linkage to 17q Markers

Association of 17q24 rs1859962 gene polymorphism with prostate cancer risk: A systematic review and meta-analysis

BACKGROUND

Recently, several genome-wide association studies have demonstrated a cumulative association of 17q24 rs1859962 gene variants with prostate cancer (PCa) risk, but conflicting results on this issue have been reported. Hence, we performed a systematic literature review and meta-analysis to assess the association between 17q24 rs1859962 gene and PCa risk.

METHODS

Systematic literature searches were conducted with PubMed, EMBASE, Science Direct/Elsevier, CNKI, and the Cochrane Library up to January 2019 for studies focusing on the association of 17q24 rs1859962 gene polymorphism with PCa risk. Meta-analysis was performed with Review Manager and stata software. Combined OR were identified with 95% confidence intervals (95% CI) in a random or fixed effects model.

RESULTS

Eight studies were identified, including 7863 cases of PCa patients and 17122 normal controls. Our results revealed significant associations between the 17q24 rs1859962 gene polymorphism and PCa in all genetic models (P < 0.05). The combined odds ratios and 95% confidence intervals were as follows: Additive model (odds ratios [ORs] 1.44, 95%, confidence interval [CI] [1.32, 1.57]); Codominant model (ORs 1.22, 95% CI [1.08, 1.39]); Dominant model (ORs 1.25, 95%, CI [1.17, 1.34]); recessive model (ORs 1.27, 95% CI [1.18, 1.36]); allele model (ORs 1.32, 95% CI [1.12, 1.55]).

CONCLUSION

The present study supports the proposed association between the 17q24 gene rs1859962 and PCa progression. Specifically, this polymorphism is suggested to be a risk factor of PCa. However, studies with larger sample sizes are needed to better illuminate the correlation between 17q24 rs1859962 gene polymorphism and PCa.

Whole exome sequencing in 75 high-risk families with validation and replication in independent case-control studies identifies TANGO2, OR5H14, and CHAD as new prostate cancer susceptibility genes

Prostate cancer (PCa) susceptibility is defined by a continuum from rare, high-penetrance to common, low-penetrance alleles. Research to date has concentrated on identification of variants at the ends of that continuum. Taking an alternate approach, we focused on the important but elusive class of low-frequency, moderately penetrant variants by performing disease model-based variant filtering of whole exome sequence data from 75 hereditary PCa families. Analysis of 341 candidate risk variants identified nine variants significantly associated with increased PCa risk in a population-based, case-control study of 2,495 men. In an independent nested case-control study of 7,121 men, there was risk association evidence for TANGO2 p.Ser17Ter and the established HOXB13 p.Gly84Glu variant. Meta-analysis combining the case-control studies identified two additional variants suggestively associated with risk, OR5H14 p.Met59Val and CHAD p.Ala342Asp. The TANGO2 and HOXB13 variants co-occurred in cases more often than expected by chance and never in controls. Finally, TANGO2 p.Ser17Ter was associated with aggressive disease in both case-control studies separately. Our analyses identified three new PCa susceptibility alleles in the TANGO2, OR5H14 and CHAD genes that not only segregate in multiple high-risk families but are also of importance in altering disease risk for men from the general population. This is the first successful study to utilize sequencing in high-risk families for the express purpose of identifying low-frequency, moderately penetrant PCa risk mutations.

The association between BRCA1 gene polymorphism and cancer risk: a meta-analysis

Many studies have reported that BRCA1 polymorphisms are associated with cancer risk, but the results remain controversial. The purpose of this meta-analysis is to evaluate the relationship between BRCA1 polymorphisms (rs799917, rs1799950, rs1799966, or rs16941) and cancer risk. Relevant studies were identified via a systematic search of the PubMed, Embase, and Web of Science databases up to July 31, 2017. Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated to examine the strength of the associations. Thirty-five studies published in 19 publications involving 28,094 cases and 50,657 controls were included in this meta-analysis. There was no obvious association between rs799917, rs1799966, or rs16941 polymorphisms and overall cancer risk in any genetic models. However, subgroup analyses revealed that the rs799917 polymorphism could decrease the risk of cervical cancer, esophageal squamous cell carcinoma (ESCC), gastric cancer, and non-Hodgkin lymphoma (NHL) among Asian populations in one or more genetic models and that rs16941 could increase overall cancer risk among Caucasian populations in the homozygote and recessive models. Our meta-analysis also indicated that rs1799950 could decrease the breast cancer (BC) risk among Caucasian populations in the homozygote and recessive models. In summary, our results suggest that BRCA1 polymorphisms may play an important role in the etiology of cancer. However, due to the limited number of studies, these findings should be confirmed by new studies with larger sample sizes that address various types of cancer.

Prevalence of the HOXB13 G84E mutation among unaffected men with a family history of prostate cancer

HOXB13 (G84E) was reported to significantly increase risk for prostate cancer. The goal of the current analysis was to assess the prevalence of G84E in ethnically-diverse high-risk men undergoing prostate cancer screening and place the carrier frequency within the context of prevalence estimates from reported studies to gain insight into the future role of this mutation in genetic counseling. PRAP is a prostate cancer screening program for unaffected men ages 35-69 with a family history of prostate cancer or African descent. HOXB13 G84E was genotyped by pyrosequencing in 649 PRAP participants with available DNA. Prevalence of the mutation was calculated for PRAP and for reported studies and exact binomial confidence intervals were generated. Prevalence of the G84E mutation in non-African PRAP men was 0.73 %. When placed in context of the literature, this was higher than reported controls. One G84E mutation carrier was notably of Hispanic background. While the HOXB13 G84E mutation may be rare, there may be a future role in genetic testing for this mutation after further studies of clinical utility in assessing prostate cancer risk.

STAT5A/B gene locus undergoes amplification during human prostate cancer progression

The molecular mechanisms underlying progression of prostate cancer (PCa) to castrate-resistant (CR) and metastatic disease are poorly understood. Our previous mechanistic work shows that inhibition of transcription factor Stat5 by multiple alternative methods induces extensive rapid apoptotic death of Stat5-positive PCa cells in vitro and inhibits PCa xenograft tumor growth in nude mice. Furthermore, STAT5A/B induces invasive behavior of PCa cells in vitro and in vivo, suggesting involvement of STAT5A/B in PCa progression. Nuclear STAT5A/B protein levels are increased in high-grade PCas, CR PCas, and distant metastases, and high nuclear STAT5A/B expression predicts early disease recurrence and PCa-specific death in clinical PCas. Based on these findings, STAT5A/B represents a therapeutic target protein for advanced PCa. The mechanisms underlying increased Stat5 protein levels in PCa are unclear. Herein, we demonstrate amplification at the STAT5A/B gene locus in a significant fraction of clinical PCa specimens. STAT5A/B gene amplification was more frequently found in PCas of high histologic grades and in CR distant metastases. Quantitative in situ analysis revealed that STAT5A/B gene amplification was associated with increased STAT5A/B protein expression in PCa. Functional studies showed that increased STAT5A/B copy numbers conferred growth advantage in PCa cells in vitro and as xenograft tumors in vivo. The work presented herein provides the first evidence of somatic STAT5A/B gene amplification in clinical PCas.

Germline mutations in HOXB13 and prostate-cancer risk

BACKGROUND

Family history is a significant risk factor for prostate cancer, although the molecular basis for this association is poorly understood. Linkage studies have implicated chromosome 17q21-22 as a possible location of a prostate-cancer susceptibility gene.

METHODS

We screened more than 200 genes in the 17q21-22 region by sequencing germline DNA from 94 unrelated patients with prostate cancer from families selected for linkage to the candidate region. We tested family members, additional case subjects, and control subjects to characterize the frequency of the identified mutations.

RESULTS

Probands from four families were discovered to have a rare but recurrent mutation (G84E) in HOXB13 (rs138213197), a homeobox transcription factor gene that is important in prostate development. All 18 men with prostate cancer and available DNA in these four families carried the mutation. The carrier rate of the G84E mutation was increased by a factor of approximately 20 in 5083 unrelated subjects of European descent who had prostate cancer, with the mutation found in 72 subjects (1.4%), as compared with 1 in 1401 control subjects (0.1%) (P=8.5x10(-7)). The mutation was significantly more common in men with early-onset, familial prostate cancer (3.1%) than in those with late-onset, nonfamilial prostate cancer (0.6%) (P=2.0x10(-6)).

CONCLUSIONS

The novel HOXB13 G84E variant is associated with a significantly increased risk of hereditary prostate cancer. Although the variant accounts for a small fraction of all prostate cancers, this finding has implications for prostate-cancer risk assessment and may provide new mechanistic insights into this common cancer. (Funded by the National Institutes of Health and others.).

Cancer biomarker discovery: the entropic hallmark

Background

It is a commonly accepted belief that cancer cells modify their transcriptional state during the progression of the disease. We propose that the progression of cancer cells towards malignant phenotypes can be efficiently tracked using high-throughput technologies that follow the gradual changes observed in the gene expression profiles by employing Shannon's mathematical theory of communication. Methods based on Information Theory can then quantify the divergence of cancer cells' transcriptional profiles from those of normally appearing cells of the originating tissues. The relevance of the proposed methods can be evaluated using microarray datasets available in the public domain but the method is in principle applicable to other high-throughput methods.

Methodology/Principal Findings

Using melanoma and prostate cancer datasets we illustrate how it is possible to employ Shannon Entropy and the Jensen-Shannon divergence to trace the transcriptional changes progression of the disease. We establish how the variations of these two measures correlate with established biomarkers of cancer progression. The Information Theory measures allow us to identify novel biomarkers for both progressive and relatively more sudden transcriptional changes leading to malignant phenotypes. At the same time, the methodology was able to validate a large number of genes and processes that seem to be implicated in the progression of melanoma and prostate cancer.

Conclusions/Significance

We thus present a quantitative guiding rule, a new unifying hallmark of cancer: the cancer cell's transcriptome changes lead to measurable observed transitions of Normalized Shannon Entropy values (as measured by high-througput technologies). At the same time, tumor cells increment their divergence from the normal tissue profile increasing their disorder via creation of states that we might not directly measure. This unifying hallmark allows, via the the Jensen-Shannon divergence, to identify the arrow of time of the processes from the gene expression profiles, and helps to map the phenotypical and molecular hallmarks of specific cancer subtypes. The deep mathematical basis of the approach allows us to suggest that this principle is, hopefully, of general applicability for other diseases.

Absence of truncating BRIP1 mutations in chromosome 17q-linked hereditary prostate cancer families

Background:

In a genome-wide scan (GWS) of 175 multiplex prostate cancer (PCa) families from the University of Michigan Prostate Cancer Genetics Project (PCGP), linkage was observed to markers on chromosome 17q21–24, a region that includes two breast cancer susceptibility genes, BRCA1 and BRIP1. BRIP1 is a Fanconi anaemia gene (FANCJ) that interacts with the BRCT domain of BRCA1 and has a role in DNA damage repair. Protein truncating mutations in BRIP1 have been identified in hereditary breast and ovarian cancer families, and a recent report suggested that a recurrent truncating mutation (R798X) may have a role in PCa susceptibility.

Methods:

We examined the role of BRIP1 mutations in hereditary PCa through sequence analysis of 94 individuals from PCGP families showing linkage to 17q.

Results:

A total of 24 single-nucleotide polymorphisms, including 7 missense variants but no protein truncating mutations, were observed.

Conclusion:

The data presented here suggest that BRIP1 truncating mutations are uncommon in PCa cases and do not account for the linkage to chromosome 17q observed in our GWS. Additional investigation is needed to determine the significance, if any, of the observed BRIP1 missense variants in hereditary PCa.

Signal transducer and activator of transcription 5A/B in prostate and breast cancers

Protein kinase signaling pathways, such as Janus kinase 2-Signal transducer and activator of transcription 5A/B (JAK2-STAT5A/B), are of significant interest in the search for new therapeutic strategies in both breast and prostate cancers. In prostate cancer, the components of the JAK2-STAT5A/B signaling pathway provide molecular targets for small-molecule inhibition of survival and growth signals of the cells. At the same time, new evidence suggests that the STAT5A/B signaling pathway is involved in the transition of organ-confined prostate cancer to hormone-refractory disease. This implies that the active JAK2-STAT5A/B signaling pathway potentially provides the means for pharmacological intervention of clinical prostate cancer progression. In addition, active STAT5A/B may serve as a prognostic marker for identification of those primary prostate cancers that are likely to progress to aggressive disease. In breast cancer, the role of STAT5A/B is more complex. STAT5A/B may have a dual role in the regulation of malignant mammary epithelium. Data accumulated from mouse models of breast cancer suggest that in early stages of breast cancer STAT5A/B may promote malignant transformation and enhance growth of the tumor. This is in contrast to established breast cancer, where STAT5A/B may mediate the critical cues for maintaining the differentiation of mammary epithelium. In addition, present data suggest that activation of STAT5A/B in breast cancer predicts favorable clinical outcome. The dual nature of STAT5A/B action in breast cancer makes the therapeutic use of STAT5 A/B more complex.

Selected aspects of inherited susceptibility to prostate cancer and tumours of different site of origin

Epidemiologic research conducted over the last two decades has led us to believe that inherited factors play an important role in the aetiology of prostate cancer, but the genes which underlie the inherited susceptibility are elusive. The most compelling associations to date are with genes involved in DNA damage repair, including BRCA2. In Poland we have initiated a programme to identify DNA variants which confer an increased risk of prostate cancer and other cancers. Here we review our recent results. We found that germline mutations in BRCA1, CHEK2 and NBS1 confer an increased prostate cancer risk in Polish men. We provide evidence that CHEK2 is a multi-organ cancer susceptibility gene. We show that inherited variation in RNASEL and MSR1 genes do not contribute to prostate cancer development in Poland.

Two variants on chromosome 17 confer prostate cancer risk, and the one in TCF2 protects against type 2 diabetes

We performed a genome-wide association scan to search for sequence variants conferring risk of prostate cancer using 1,501 Icelandic men with prostate cancer and 11,290 controls. Follow-up studies involving three additional case-control groups replicated an association of two variants on chromosome 17 with the disease. These two variants, 33 Mb apart, fall within a region previously implicated by family-based linkage studies on prostate cancer. The risks conferred by these variants are moderate individually (allele odds ratio of about 1.20), but because they are common, their joint population attributable risk is substantial. One of the variants is in TCF2 (HNF1beta), a gene known to be mutated in individuals with maturity-onset diabetes of the young type 5. Results from eight case-control groups, including one West African and one Chinese, demonstrate that this variant confers protection against type 2 diabetes.

Common variation in the BRCA1 gene and prostate cancer risk

Rare inactivating mutations in the BRCA1 gene seem to play a limited role in prostate cancer. To our knowledge, however, no study has comprehensively assessed the role of other BRCA1 sequence variations (e.g., missense mutations) in prostate cancer. In a study of 817 men with and without prostate cancer from 323 familial and early-onset prostate cancer families, we used family-based association tests and conditional logistic regression to investigate the association between prostate cancer and single nucleotide polymorphisms (SNPs) tagging common haplotype variation in a 200-kb region surrounding (and including) the BRCA1 gene. We also used the Genotype-Identity-by-Descent Sharing Test to determine whether our most strongly associated SNP could account for prostate cancer linkage to chromosome 17q21 in a sample of 154 families from our previous genome-wide linkage study. The strongest evidence for prostate cancer association was for a glutamine-to-arginine substitution at codon 356 (Gln(356)Arg) in exon 11 of the BRCA1 gene. The minor (Arg) allele was preferentially transmitted to affected men (P = 0.005 for a dominant model), with an estimated odds ratio of 2.25 (95% confidence interval, 1.21-4.20). Notably, BRCA1 Gln(356)Arg is not in strong linkage disequilibrium with other BRCA1 coding SNPs or any known HapMap SNP on chromosome 17. In addition, Genotype-Identity-by-Descent Sharing Test results suggest that Gln(356)Arg accounts (in part) for our prior evidence of prostate cancer linkage to chromosome 17q21 (P = 0.022). Thus, we have identified a common, nonsynonymous substitution in the BRCA1 gene that is associated with and linked to prostate cancer.

Identification of a recurrent t(4;6) chromosomal translocation in prostate cancer

PURPOSE

We developed and describe a practical method by which primary prostate cancer specimens can be screened for recurrent chromosomal translocations, which is a potential source of fusion genes, as well as a process by which identified translocations can be mapped to define the genes involved.

MATERIALS AND METHODS

A series of 7 prostate cancer cell lines and 25 transiently established primary cell cultures, which were sourced from tissue harvested at 16 radical prostatectomies and 9 channel transurethral prostate resections, were screened for chromosomal translocations using multiplex-fluorescence in situ hybridization technology. A series of fluorescence in situ hybridization based breakpoint mapping experiments were performed to identify candidate genes involved in regions associated with recurrent translocation.

RESULTS

Our analysis identified the repetition of 2 translocations in prostate cancer lines, that is t(1;15) and t(4;6), at a frequency of 28% and 57%, respectively. More significantly 4 of the 25 subsequently established primary cultures (16%) also revealed a t(4;6) translocation. Using the LNCaP cell line the breakpoints involved were mapped to the t(4;6)(q22;q15) region and a number of candidate genes were identified.

CONCLUSIONS

We found that the t(4;6) translocation is also a repeat event in primary cell cultures from malignant prostate cancer. Breakpoint mapping showed that the gene UNC5C loses its promoter and first exon as a direct result of the translocation in the 4q22 region. As such, we identified it as a possible contributor to a putative fusion gene in prostate cancer.

Fine-mapping the putative chromosome 17q21-22 prostate cancer susceptibility gene to a 10 cM region based on linkage analysis

Prostate cancer linkage studies have suggested the existence of a prostate cancer susceptibility gene on chromosome 17q21-22. We now report the results of an extended linkage analysis including 95 new multiplex prostate cancer families and 9 additional microsatellite markers resulting in a maximum LOD score of 2.99 at approximately 81-82 cM for all 453 pedigrees. Results from these 95 new pedigrees provide additional support for a chromosome 17q21-22 prostate cancer susceptibility gene. Inclusion of the 9 additional markers significantly reduced the size of the candidate region, as defined using a 1-LOD support interval, especially when focusing analyses on subsets of pedigrees with four or more confirmed affecteds or average age of diagnosis less than or equal to 65 years. A novel subset analysis of only those families (n = 147) that had four or more prostate cancer cases and an average age of prostate cancer diagnosis < or = 65 years results in a maximum LOD score of 5.49 at 78 cM with a 1-LOD support interval of 10 cM. This large set of pedigrees with four more prostate cancer cases characterized by early-onset disease will serve as a useful resource for identifying the putative 17q21-22 prostate cancer susceptibility gene.

Association between family history of prostate and breast cancer among African-American men with prostate cancer

OBJECTIVES

To explore the familial aggregation of prostate and breast cancer using data from a population-based case-control study of African-American men participating in the Flint Men's Health Study.

METHODS

A detailed family history questionnaire was administered to 121 African-American men with prostate cancer and 179 African-American male controls. The family history data of prostate and breast cancer in first-degree relatives were compared between men with and without prostate cancer using standard statistical methods.

RESULTS

In the Flint Men's Health Study, men with prostate cancer were more likely than controls to report having a brother with prostate cancer (age-adjusted odds ratio 4.80, 95% confidence interval 2.01 to 11.44) or a sister with breast cancer (age-adjusted odds ratio 3.80, 95% confidence interval 1.57 to 9.22).

CONCLUSIONS

Although a family history of prostate cancer is a recognized prostate cancer risk factor consistent across different races, few studies have examined the co-clustering of breast and prostate cancer within African-American families. Future studies should focus on racially heterogeneous populations to further explore the observation from the Flint Men's Health Study that having a brother with prostate cancer or a sister with breast cancer may be associated with prostate cancer occurrence. This research may have implications for both gene identification and early detection strategies.

Prohibitin mutations are uncommon in prostate cancer families linked to chromosome 17q

BACKGROUND

Linkage studies have provided evidence for a prostate cancer susceptibility locus on chromosome 17q. The mitochondrial protein prohibitin (PHB) is a plausible candidate gene based on its chromosomal location (17q21) and known function.

METHODS

All coding regions and intron/exon junctions of the PHB gene were sequenced in 32 men from families participating in the University of Michigan Prostate Cancer Genetics Project that demonstrated evidence of linkage to 17q markers.

RESULTS

Although a number of nucleotide variants were identified, no coding region substitutions were identified in any of the 32 men with prostate cancer from 32 unrelated multiplex prostate cancer families.

CONCLUSIONS

PHB mutations do not appear to account for the linkage signal on 17q21-22 detected in PCGP families. Fine mapping of this region is in progress to refine the candidate region and highlight additional candidate prostate cancer susceptibility genes for sequence analysis.