A novel germline mutation in HOXB13 is associated with prostate cancer risk in Chinese men

Clinical and Functional Analyses of an African-ancestry Gain-of-function HOXB13 Variant Implicated in Aggressive Prostate Cancer

BACKGROUND

Recent reports have uncovered a HOXB13 variant (X285K) predisposing to prostate cancer in men of West African ancestry. The clinical relevance and protein function associated with this inherited variant are unknown.

OBJECTIVE

To determine the clinical relevance of HOXB13 (X285K) in comparison with HOXB13 (G84E) and BRCA2 pathogenic/likely pathogenic (P/LP) variants, and to elucidate the oncogenic mechanisms of the X285K protein.

DESIGN, SETTING, AND PARTICIPANTS

Real-world data were collected from 21,393 men with prostate cancer undergoing genetic testing from 2019 to 2022, and in vitro cell-line models were established for the evaluation of oncogenic functions associated with the X285K protein.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Genetic testing results were compared among patient groups according to self-reported race/ethnicity, Gleason scores, and American Joint Committee on Cancer stages using the exact test. Oncogenic functions of X285K were evaluated by RNA sequencing, chromatin immunoprecipitation sequencing, and Western blot analyses.

RESULTS AND LIMITATIONS

HOXB13 (X285K) was significantly enriched in self-reported Black (1.01%) versus White (0.01%) patients. We observed a trend of more aggressive disease in the HOXB13 (X285K) and BRCA2 P/LP carriers than in the HOXB13 (G84E) carriers. Replacement of the wild-type HOXB13 protein with the X285K protein resulted in a gain of an E2F/MYC signature, validated by the elevated expression of cyclin B1 and c-Myc, without affecting the androgen response signature. Elevated expression of cyclin B1 and c-Myc was explained by enhanced binding of the X285K protein to the promoters and enhancers of these genes. The limitations of the study are the lack of complete clinical outcome data for all patients studied and the use of a single cell line in the functional analysis.

CONCLUSIONS

HOXB13 (X285K) is significantly enriched in self-reported Black patients, and X285K carriers detected in the real-world clinical setting have aggressive prostate cancer features similar to the BRCA2 carriers. Functional studies revealed a unique gain-of-function oncogenic mechanism of X285K protein in regulating E2F/MYC signatures.

PATIENT SUMMARY

The HOXB13 (X285K) variant is clinically and functionally linked to aggressive prostate cancer, supporting genetic testing for X285K in Black men and early disease screening of carriers of this variant.

Disrupting prostate cancer research: Challenge accepted; report from the 2023 Coffey-Holden Prostate Cancer Academy Meeting

INTRODUCTION

The 2023 Coffey-Holden Prostate Cancer Academy (CHPCA) Meeting, themed "Disrupting Prostate Cancer Research: Challenge Accepted," was convened at the University of California, Los Angeles, Luskin Conference Center, in Los Angeles, CA, from June 22 to 25, 2023.

METHODS

The 2023 marked the 10th Annual CHPCA Meeting, a discussion-oriented scientific think-tank conference convened annually by the Prostate Cancer Foundation, which centers on innovative and emerging research topics deemed pivotal for advancing critical unmet needs in prostate cancer research and clinical care. The 2023 CHPCA Meeting was attended by 81 academic investigators and included 40 talks across 8 sessions.

RESULTS

The central topic areas covered at the meeting included: targeting transcription factor neo-enhancesomes in cancer, AR as a pro-differentiation and oncogenic transcription factor, why few are cured with androgen deprivation therapy and how to change dogma to cure metastatic prostate cancer without castration, reducing prostate cancer morbidity and mortality with genetics, opportunities for radiation to enhance therapeutic benefit in oligometastatic prostate cancer, novel immunotherapeutic approaches, and the new era of artificial intelligence-driven precision medicine.

DISCUSSION

This article provides an overview of the scientific presentations delivered at the 2023 CHPCA Meeting, such that this knowledge can help in facilitating the advancement of prostate cancer research worldwide.

Clinicopathological Characteristics and Mutational Landscape of APC, HOXB13, and KRAS among Rwandan Patients with Colorectal Cancer

Cancer research in Rwanda is estimated to be less than 1% of the total African cancer research output with limited research on colorectal cancer (CRC). Rwandan patients with CRC are young, with more females being affected than males, and most patients present with advanced disease. Considering the paucity of oncological genetic studies in this population, we investigated the mutational status of CRC tissues, focusing on the Adenomatous polyposis coli (APC), Kirsten rat sarcoma (KRAS), and Homeobox B13 (HOXB13) genes. Our aim was to determine whether there were any differences between Rwandan patients and other populations. To do so, we performed Sanger sequencing of the DNA extracted from formalin-fixed paraffin-embedded adenocarcinoma samples from 54 patients (mean age: 60 years). Most tumors were located in the rectum (83.3%), and 92.6% of the tumors were low-grade. Most patients (70.4%) reported never smoking, and 61.1% of patients had consumed alcohol. We identified 27 variants of APC, including 3 novel mutations (c.4310_4319delAAACACCTCC, c.4463_4470delinsA, and c.4506_4507delT). All three novel mutations are classified as deleterious by MutationTaster2021. We found four synonymous variants (c.330C>A, c.366C>T, c.513T>C, and c.735G>A) of HOXB13. For KRAS, we found six variants (Asp173, Gly13Asp, Gly12Ala, Gly12Asp, Gly12Val, and Gln61His), the last four of which are pathogenic. In conclusion, here we contribute new genetic variation data and provide clinicopathological information pertinent to CRC in Rwanda.

Exome sequencing of affected duos and trios uncovers PRUNE2 as a novel prostate cancer predisposition gene

BACKGROUND

Prostate cancer (PrCa) is one of the most hereditable human cancers, however, only a small fraction of patients has been shown to carry deleterious variants in known cancer predisposition genes.

METHODS

Whole-exome sequencing was performed in multiple affected members of 45 PrCa families to select the best candidate genes behind part of the PrCa missing hereditability. Recurrently mutated genes were prioritised, and further investigated by targeted next-generation sequencing in the whole early-onset and/or familial PrCa series of 462 patients.

RESULTS

PRUNE2 stood out from our analysis when also considering the available data on its association with PrCa development. Ten germline pathogenic/likely pathogenic variants in the PRUNE2 gene were identified in 13 patients. The most frequent variant was found in three unrelated patients and identical-by-descent analysis revealed that the haplotype associated with the variant is shared by all the variant carriers, supporting the existence of a common ancestor.

DISCUSSION

This is the first report of pathogenic/likely pathogenic germline variants in PRUNE2 in PrCa patients, namely in those with early-onset/familial disease. Importantly, PRUNE2 was the most frequently mutated gene in the whole series, with a deleterious germline variant identified in 2.8% of the patients, representing a novel prostate cancer predisposition gene.

Prognostic significance of pathogenic variants in BRCA1, BRCA2, ATM and PALB2 genes in men undergoing hormonal therapy for advanced prostate cancer

BACKGROUND

The prognostic significance of germline variants in homologous recombination repair genes in advanced prostate cancer (PCa), especially with regard to hormonal therapy, remains controversial.

METHODS

Germline DNA from 549 Japanese men with metastatic and/or castration-resistant PCa was sequenced for 27 cancer-predisposing genes. The associations between pathogenic variants and clinical outcomes were examined. Further, for comparison, DNA from prostate biopsy tissue samples from 80 independent patients with metastatic PCa were analysed.

RESULTS

Forty-four (8%) patients carried germline pathogenic variants in one of the analysed genes. BRCA2 was most frequently altered (n = 19), followed by HOXB13 (n = 9), PALB2 (n = 5) and ATM (n = 5). Further, the BRCA1, BRCA2, PALB2 and ATM variants showed significant association with a short time to castration resistance and overall survival (hazard ratio = 1.99 and 2.36; 95% CI, 1.15-3.44 and 1.23-4.51, respectively), independent of other clinical variables. Based on log-rank tests, the time to castration resistance was also significantly short in patients with BRCA1, BRCA2, PALB2 or ATM somatic mutations and TP53 mutations.

CONCLUSIONS

Germline variants in BRCA1, BRCA2, PALB2 or ATM are independent prognostic factors of the short duration of response to hormonal therapy in advanced PCa.

Variants in HOXB13, G132E and F127C, Are Associated With Prostate Cancer Risk in Japanese Men

BACKGROUND/AIM

Several studies have reported on the relationship between HOXB13 variants and an increased prostate cancer (PC) risk. To our knowledge there are not many studies on HOXB13 mutations in Japanese patients with prostate cancer, and there many issues remain uninvestigated. We herein clarified the association between HOXB13 genetic variants and PC risk in a Japanese population.

PATIENTS AND METHODS

PC patients were diagnosed at the Gunma University Hospital and affiliated hospitals from 1994 to 2016. Sanger sequencing was performed on the coding regions of the HOXB13 gene in 152 familial PC (FPC) patients. Genotyping was performed on single nucleotide variants (SNVs) found in Sanger sequencing in 230 FPC patients from 152 pedigrees and 197 sporadic PC (SPC) patients and 144 controls. Allelic frequency and clinical data for each variant were studied in cases and controls.

RESULTS

G132E and F127C were identified in FPC patients. The frequencies of G132E and F127C were significantly higher compared to the control group (p=0.039). In three families, seven PC patients shared the G132E variant, within second-to-third-degree relatives. It was not possible to clarify to pathogenicity of each SNV alone.

CONCLUSION

We found two significant variants of the HOXB13 gene, G132E, F127C by analyzing and comparing gene samples from PC and non-PC patients. Furthermore, the HOXB13 G132E variant was found significantly increased in the FPC group.

Germline Mutations in Patients With Early-Onset Prostate Cancer

Objective

To investigate the inherited mutations and their association with clinical features and treatment response in young-onset prostate cancer patients.

Method

Targeted gene sequencing on 139 tumor susceptibility genes was conducted with a total of 24 patients diagnosed with PCa under the age of 63 years old. Meanwhile, the related clinical information of those patients is collected and analyzed.

Results

Sixty-two germline mutations in 45 genes were verified in 22 patients. BRCA2 (20.8%) and GJB2 (20.8%) were found to be the most frequently mutated, followed by CHEK2, BRCA1, PALB2, CDKN2A, HOXB13, PPM1D, and RECQL (8.3% of each, 2/24). Of note, 58.3% (14/24) patients carry germline mutations in DNA repair genes (DRGs). Four families with HRR (homologous recombination repair)-related gene mutations were described and analyzed in detail. Two patients with BRCA2 mutation responded well to the combined treatment of androgen deprivation therapy (ADT) and radiotherapy/chemotherapy.

Conclusion

Mutations in DRGs are more prevalent in early-onset PCa with advanced clinical stages, and these patients had shorter progression-free survival. ADT Combined with either radiotherapy or chemotherapy may be effective in treating PCa caused by HRR-related gene mutations.

Health inequity drives disease biology to create disparities in prostate cancer outcomes

Prostate cancer exerts a greater toll on African American men than on White men of European descent (hereafter referred to as European American men): the disparity in incidence and mortality is greater than that of any other common cancer. The disproportionate impact of prostate cancer on Black men has been attributed to the genetics of African ancestry, to diet and lifestyle risk factors, and to unequal access to quality health care. In this Review, all of these influences are considered in the context of the evolving understanding that chronic or recurrent inflammatory processes drive prostatic carcinogenesis. Studies of inherited susceptibility highlight the contributions of genes involved in prostate cell and tissue repair (BRCA1/2, ATM) and regeneration (HOXB13 and MYC). Social determinants of health appear to accentuate these genetic influences by fueling prostate inflammation and associated cell and genome damage. Molecular characterization of the prostate cancers that arise in Black versus White men further implicates this inflammatory microenvironment in disease behavior. Yet, when Black and White men with similar grade and stage of prostate cancer are treated equally, they exhibit equivalent outcomes. The central role of prostate inflammation in prostate cancer development and progression augments the impact of the social determinants of health on disease pathogenesis. And, when coupled with poorer access to high-quality treatment, these inequities result in a disparate burden of prostate cancer on African American men.

A Rare Germline HOXB13 Variant Contributes to Risk of Prostate Cancer in Men of African Ancestry

A rare African ancestry-specific germline deletion variant in HOXB13 (X285K, rs77179853) was recently reported in Martinican men with early-onset prostate cancer. Given the role of HOXB13 germline variation in prostate cancer, we investigated the association between HOXB13 X285K and prostate cancer risk in a large sample of 22 361 African ancestry men, including 11 688 prostate cancer cases. The risk allele was present only in men of West African ancestry, with an allele frequency in men that ranged from 0.40% in Ghana and 0.31% in Nigeria to 0% in Uganda and South Africa, with a range of frequencies in men with admixed African ancestry from North America and Europe (0-0.26%). HOXB13 X285K was associated with 2.4-fold increased odds of prostate cancer (95% confidence interval [CI] = 1.5-3.9, p = 2 × 10^-4), with greater risk observed for more aggressive and advanced disease (Gleason ≥8: odds ratio [OR] = 4.7, 95% CI = 2.3-9.5, p = 2 × 10^-5; stage T3/T4: OR = 4.5, 95% CI = 2.0-10.0, p = 2 × 10^-4; metastatic disease: OR = 5.1, 95% CI = 1.9-13.7, p = 0.001). We estimated that the allele arose in West Africa 1500-4600 yr ago. Further analysis is needed to understand how the HOXB13 X285K variant impacts the HOXB13 protein and function in the prostate. Understanding who carries this mutation may inform prostate cancer screening in men of West African ancestry. PATIENT SUMMARY: A rare African ancestry-specific germline deletion in HOXB13, found only in men of West African ancestry, was reported to be associated with an increased risk of overall and advanced prostate cancer. Understanding who carries this mutation may help inform screening for prostate cancer in men of West African ancestry.

Clinical Utility of Germline Genetic Testing in Japanese Men Undergoing Prostate Biopsy

Background

Multiple common variants and also rare variants in monogenic risk genes such as BRCA2 and HOXB13 have been reported to be associated with risk of prostate cancer (PCa); however, the clinical setting in which germline genetic testing could be used for PCa diagnosis remains obscure. Herein, we tested the clinical utility of a 16 common variant–based polygenic risk score (PRS) that has been developed previously for Japanese men and also evaluated the frequency of PCa-associated rare variants in a prospective cohort of Japanese men undergoing prostate biopsy.

Methods

A total of 1336 patients undergoing first prostate biopsy were included. PRS was calculated based on the genotype of 16 common variants, and sequencing of 8 prostate cancer–associated genes was performed by multiplex polymerase chain reaction based target sequencing. PRS was combined with clinical factors in logistic regression models to assess whether addition of PRS improves the prediction of biopsy positivity.

Results

The top PRS decile was associated with an odds ratio of 4.10 (95% confidence interval = 2.46 to 6.86) with reference to the patients at average risk, and the estimated lifetime absolute risk approached 20%. Among the patients with prostate specific antigen 2-10 ng/mL who had prebiopsy magnetic resonance imaging, high PRS had an equivalent impact on biopsy positivity as a positive magnetic resonance imaging finding. Rare variants were detected in 19 (2.37%) and 7 (1.31%) patients with positive and negative biopsies, respectively, with BRCA2 variants being the most prevalent. There was no association between PRS and high-risk rare variants.

Conclusions

Germline genetic testing could be clinically useful in both pre- and post-PSA screening settings.

Racial Differences in Prostate Cancer Characteristics and Cancer-Specific Mortality: An Overview

Racial differences of prostate cancer incidence and mortality among Asian, Black, and Caucasian men have been known, however, comprehensive update of this topic is not yet reported. In the present review, an overview of the racial differences in prostate cancer characteristics and cancer-specific mortality is collected and reviewed. Regarding racial differences of incidence and mortality, surprising differences in the incidence of prostate cancer are seen among different populations around the world, with some countries having rates that are 60 to 100 times higher than others. African-American men have a higher incidence of prostate cancer, higher prostate cancer mortality, and are diagnosed with prostate cancer at a younger age than Caucasian American men. Furthermore, race is gaining attention as an important factor to consider for planning active surveillance for localized prostate cancer, especially among African-Americans. In addition, the causes of these differences are being elucidated by genomic profiling. Determinants of racial disparities are multifactorial, including socioeconomic and biologic factors. Although race-specific differences in prostate cancer survival estimates appear to be narrowing over time, there is an ongoing need to continue to understand and mitigate racial factors associated with disparities in health care outcomes.

Clinical Significance of Gene Mutations and Polymorphic Variants and their Association with Prostate Cancer Risk in Polish Men

Objectives: We tested the association of germline variants in BRCA1, BRCA2, CHEK2, CDKN2A, CYP1B1, HOXB13, MLH1, NBS1, NOD2 andPALB2 genes, as well as in 8q24 region, with prostate cancer (PC) risk and estimated their impact on disease clinical course, including overall survival time in Polish men with localized PC qualified for radical treatment.Materials and Methods: DNA of 110 patients with localized prostate cancer treated with radical prostatectomy (RP), from each age group and with different stages of the disease. DNA samples of the control group consisted of 111 men, volunteers, without PC (age-matched to study group). Sanger sequencing, AS-PCR, RFLP-PCR, and multiplex-PCR were used for  variants detection.Results: The percentage of men with ≥1 germline variant was higher in PC group (52.7%) than in healthy men (37.8%) (P = .03). The presence of ≥2 variants was associated with shorter survival than the presence of one or no variant in the PC group (P = .14, trend). The HOXB13 G84E was detected in 2.9% of PC men and in no healthy men (P = .19, trend, OR = 7.21). A CHEK2 truncating mutation (1100delC or IVS2+1G>A) was detected in 2/110 (1.8%) PC patients and in no healthy men (P = .29, OR=5.14). The NBS1 I171V was detected in 2/110 (1.8%) PC patients and in no men from the control group (OR=5.14, P = .29, NS).Conclusions: We conclude that the presence of more than 2 germline variants was probably associated with shorter survival of patients with localized prostate cancer qualified for radical treatment. The HOXB13 (G84E), CHEK2 (1100delC or IVS2+1G>A) truncating variants and NBS1 (I171V) are associated with PC and hereditary form of the disease. The HOXB13 (G84E) and NOD2 (3020insC) single variants are associated with shorter and CYP1B1 (48CC, 119GG) single genotypes with longer overall survival.

The HOXB13 variant X285K is associated with clinical significance and early age at diagnosis in African American prostate cancer patients

BACKGROUND

Recently, a novel HOXB13 variant (X285K) was observed in men of African descent with prostate cancer (PCa) in Martinique. Little is known about this or other variants in HOXB13 which may play a role in PCa susceptibility in African-American (AA) men.

METHODS

We sequenced HOXB13 in an AA population of 1048 men undergoing surgical treatment for PCa at Johns Hopkins Hospital.

RESULTS

Seven non-synonymous germline variants were observed in the patient population. While six of these variants were seen only once, X285K was found in eight patients. In a case-case analysis, we find that carriers of this latter variant are at increased risk of clinically significant PCa (1.2% carrier rate in Gleason Score ≥7 PCa vs. 0% in Gleason Score <7 PCa, odds ratio, OR = inf; 95% Confidence Interval, 95%CI:1.05-inf, P = 0.028), as well as PCa with early age at diagnosis (2.4% carrier rate in patients <50 year vs. 0.5% carrier rate in patients ≥50 year, OR = 5.25, 95% CI:1.00-28.52, P = 0.03).

CONCLUSIONS

While this variant is rare in the AA population (~0.2% MAF), its ancestry-specific occurrence and apparent preferential association with risk for the more aggressive disease at an early age emphasizes its translational potential as an important, novel PCa susceptibility marker in the high-risk AA population.

Inherited Mutations in Chinese Men With Prostate Cancer

BACKGROUND

Although China accounts for 7.8% of worldwide new prostate cancer (PCa) cases and 14.5% of new deaths according to GLOBOCAN 2020, the risk of PCa associated with germline mutations is poorly defined, hampered in part by lack of nationwide evidence. Here, we sequenced 19 PCa predisposition genes in 1,836 Chinese patients with PCa and estimated disease risk associated with inherited mutations.

PATIENTS AND METHODS

Patients were recruited from 4 tertiary cancer centers (n=1,160) and a commercial laboratory (n=676). Germline DNA was sequenced using a multigene panel, and pathogenic/likely pathogenic (P/LP) mutation frequencies in patients with PCa were compared with populations from the gnomAD (Genome Aggregation Database) and ChinaMAP (China Metabolic Analytics Project) databases. Clinical characteristics and progression-free survival were assessed by mutation status.

RESULTS

Of 1,160 patients from hospitals, 89.7% had Gleason scores ≥8, and 65.6% had metastases. P/LP mutations were identified in 8.49% of Chinese patients with PCa. Association with PCa risk was significant for mutations in ATM (odds ratio [OR], 5.9; 95% CI, 3.1-11.1), BRCA2 (OR, 15.3; 95% CI, 10.0-23.2), MSH2 (OR, 15.8; 95% CI, 4.2-59.6), and PALB2 (OR, 5.9; 95% CI, 2.7-13.2). Compared with those without mutations, patients with mutations in ATM, BRCA2, MSH2, or PALB2 showed a poor outcome with treatment using androgen deprivation therapy and abiraterone (hazard ratio, 2.19 [95% CI, 1.34-3.58] and 2.47 [95% CI, 1.23-4.96], respectively) but similar benefit from docetaxel.

CONCLUSIONS

The present multicenter study confirmed that a significant proportion of Chinese patients with PCa had inherited mutations and identified predisposition genes in this underreported ethnicity. These data provide empirical evidence for precision prevention and prognostic estimation in Chinese patients with PCa.

Germline Predisposition to Prostate Cancer in Diverse Populations

There remains a paucity of data related to germline genetic alterations predisposing patients to prostate cancer. Recent data suggest that African American, Hispanic, and Asian and Pacific Islander men exhibit genetic alterations in both highly penetrant germline genes, including BRCA1/2, ATM, and CHEK2, and the mismatch repair genes associated with Lynch syndrome, as well as low-penetrant single-nucleotide polymorphisms. However, cohort sizes remain small in many studies limiting the ability to determine clinical significance, appropriate risk stratification, and treatment implications in these diverse populations.

Epidemiology and genomics of prostate cancer in Asian men

Prostate cancer is a global health problem, but incidence varies considerably across different continents. Asia is traditionally considered a low-incidence area, but the incidence and mortality of prostate cancer have rapidly increased across the continent. Substantial differences in epidemiological features have been observed among different Asian regions, and incidence, as well as mortality-to-incidence ratio, is associated with the human development index. Prostate cancer mortality decreased in Japan and Israel from 2007 to 2016, but mortality has increased in Thailand, Kyrgyzstan and Uzbekistan over the same period. Genomic analyses have shown a low prevalence of ERG oncoprotein in the East Asian population, alongside a low rate of PTEN loss, high CHD1 enrichments and high FOXA1 alterations. Contributions from single-nucleotide polymorphisms to prostate cancer risk vary with ethnicity, but germline mutation rates of DNA damage repair genes in metastatic prostate cancer are comparable in Chinese and white patients from the USA and UK. Pharmacogenomic features of testosterone metabolism might contribute to disparities seen in the response to androgen deprivation between East Asian men and white American and European men. Overall, considerable diversity in epidemiology and genomics of prostate cancer across Asia defines disease characteristics in these populations, but studies in this area are under-represented in the literature. Taking into account this intracontinental and intercontinental heterogeneity, translational studies are required in order to develop ethnicity-specific treatment strategies.

[Familial prostate cancer and genetic predisposition]

BACKGROUND

Twenty percent of all prostate cancer patients have a positive family history (at least 1 first-degree relative with prostate cancer) and a part of these patients have a genetic predisposition.

OBJECTIVES

A literature search and analysis of studies investigating incidence, diagnosis, and clinical course of familial compared to sporadic prostate cancer as well as genetic predisposition was performed using PubMed and Embase.

RESULTS

Risk of prostate cancer depends on number, degree of relationship, and age of onset of affected men in the family. The incidence of familial prostate cancer is higher and the age of diagnosis lower compared to sporadic cases. The clinical course of the disease is comparable, but in individuals with a germline mutation, more intensive therapy is needed due to a more aggressive disease.

CONCLUSIONS

Crucial for risk assessment is a detailed family history, including creation of a pedigree with cancer family history if necessary. In high-risk families, genetic counselling and annual prostate-specific antigen (PSA) screening beginning at the age of 40 should be performed. Verification of a germline mutation requires more intensive therapy due to more aggressive disease.

Identification of Germline Genetic Variants that Increase Prostate Cancer Risk and Influence Development of Aggressive Disease

Prostate cancer (PrCa) is a heterogeneous disease, which presents in individual patients across a diverse phenotypic spectrum ranging from indolent to fatal forms. No robust biomarkers are currently available to enable routine screening for PrCa or to distinguish clinically significant forms, therefore late stage identification of advanced disease and overdiagnosis plus overtreatment of insignificant disease both remain areas of concern in healthcare provision. PrCa has a substantial heritable component, and technological advances since the completion of the Human Genome Project have facilitated improved identification of inherited genetic factors influencing susceptibility to development of the disease within families and populations. These genetic markers hold promise to enable improved understanding of the biological mechanisms underpinning PrCa development, facilitate genetically informed PrCa screening programmes and guide appropriate treatment provision. However, insight remains largely lacking regarding many aspects of their manifestation; especially in relation to genes associated with aggressive phenotypes, risk factors in non-European populations and appropriate approaches to enable accurate stratification of higher and lower risk individuals. This review discusses the methodology used in the elucidation of genetic loci, genes and individual causal variants responsible for modulating PrCa susceptibility; the current state of understanding of the allelic spectrum contributing to PrCa risk; and prospective future translational applications of these discoveries in the developing eras of genomics and personalised medicine.

HOXB13 and TFF3 can contribute to the prognostic stratification of prostate adenocarcinoma

Homeobox B13 (HOXB13) and trefoil factor 3 (TFF3) are novel candidates for the classification of prostate cancer (PC) in molecular subtypes that could predict the clinical evolution of patients. The aim of our study was to analyze the possible associations between HOXB13 and TFF3 immunohistochemical (IHC) expression in sporadic prostate adenocarcinoma (PAC), the potential prognostic value in relation to the classical clinico-pathological parameters, as well as their role in defining distinct molecular subtypes of this malignancy. The study group comprised 105 patients diagnosed with PAC who underwent radical prostatectomy. IHC exam was performed using anti-HOXB13 and anti-TFF3 antibodies and a scoring system that permit the separation of the cases into two subgroups, with low and high immunoexpression, respectively. The statistical analysis evaluated the relationship between the two immunomarkers and clinico-pathological parameters. The Kaplan-Meier curves and log-rank Mantel-Cox test were used for assessing the prostate-specific antigen (PSA)-progression free survival. Four subgroups of PAC were defined based on the IHC overexpression and low immunoexpression of HOXB13 and TFF3. High HOXB13 and TFF3 immunoexpression was commonly identified in cases characterized by a Gleason score over 7, a G4 or G5 dominant pattern, a grade group of 3 or 4 and a preoperatory PSA serum level over 20 ng/mL. HOXB13 overexpression was also associated with pathological tumor-node-metastasis (pTNM) stage. The subgroup with both low HOXB13 and TFF3 immunoexpression had the highest PSA-progression free interval, whereas the subgroup with high HOXB13 immunoexpression and low TFF3 immunoexpression presented the lowest rate, but no statistically significant differences were registered. Our results sustain the role of HOXB13 and TFF3 in the stratification of PAC. Further investigations in larger cohorts are imposed to validate the clinical significance of these subgroups in the diagnostic and prognostic of PAC.

Germline Pathogenic Variants in 7636 Japanese Patients With Prostate Cancer and 12 366 Controls

Background

Genetic testing has been conducted in patients with prostate cancer (PCa) using multigene panels, but no centralized guidelines for genetic testing exist. To overcome this limitation, we investigated the demographic and clinical characteristics of patients with pathogenic variants.

Methods

We sequenced eight genes associated with hereditary PCa in 7636 unselected Japanese patients with PCa and 12 366 male, cancer-free control individuals. We assigned clinical significance for all 1456 variants using the American College of Medical Genetics and Genomics guidelines and ClinVar. We compared the frequency of carriers bearing pathogenic variants between cases and control participants with calculated PCa risk in each gene and documented the demographic and clinical characteristics of patients bearing pathogenic variants. All statistical tests were two-sided.

Results

We identified 136 pathogenic variants, and 2.9% of patients and 0.8% of control individuals had a pathogenic variant. Association with PCa risk was statistically significant for variants in BRCA2 (P < .001, odds ratio [OR] = 5.65, 95% confidence interval [CI] = 3.55 to 9.32), HOXB13 (P < .001, OR = 4.73, 95% CI = 2.84 to 8.19), and ATM (P < .001, OR = 2.86, 95% CI = 1.63 to 5.15). We detected recurrent new pathogenic variants such as p.Gly132Glu of HOXB13. Patients with pathogenic variants were 2.0 years younger at diagnosis and more often had smoking and alcohol drinking histories as well as family histories of breast, pancreatic, lung, and liver cancers.

Conclusions

This largest sequencing study of PCa heredity provides additional evidence supporting the latest consensus among clinicians for developing genetic testing guidelines for PCa.

Hereditary Predisposition to Prostate Cancer: From Genetics to Clinical Implications

Prostate cancer (PrCa) ranks among the top five cancers for both incidence and mortality worldwide. A significant proportion of PrCa susceptibility has been attributed to inherited predisposition, with 10-20% of cases expected to occur in a hereditary/familial context. Advances in DNA sequencing technologies have uncovered several moderate- to high-penetrance PrCa susceptibility genes, most of which have previously been related to known hereditary cancer syndromes, namely the hereditary breast and ovarian cancer (BRCA1, BRCA2, ATM, CHEK2, and PALB2) and Lynch syndrome (MLH1, MSH2, MSH6, and PMS2) genes. Additional candidate genes have also been suggested, but further evidence is needed to include them in routine genetic testing. Recommendations based on clinical features, family history, and ethnicity have been established for more cost-efficient genetic testing of patients and families who may be at an increased risk of developing PrCa. The identification of alterations in PrCa predisposing genes may help to inform screening strategies, as well as treatment options, in the metastatic setting. This review provides an overview of the genetic basis underlying hereditary predisposition to PrCa, the current genetic screening recommendations, and the implications for clinical management of the disease.

Identification of genetic biomarkers in urine for early detection of prostate cancer

Prostate cancer screening is a challenging and vital issue in the aspects of the current tests and risk assessments. Prostate cancer risk assessments are currently carried out by using blood, urine and tissue biomarkers with radiological imaging methods. Here, we introduce a novel noninvasive screening tool for a further in-depth selection of eligible cases for prostate biopsies which is based on sequencing somatic and hereditary HOXB13 mutations in urine samples. This approach provides diagnostic information to the physician about the presence of prostate cancer while aiming to screen for specific prostate biopsies and save biopsies potentially when there are no mutations related to prostate cancer. Findings suggest that this method is reliable, cost-effective, and has a promising potential in prostate cancer screening.

MEIS-mediated suppression of human prostate cancer growth and metastasis through HOXB13-dependent regulation of proteoglycans

The molecular roles of HOX transcriptional activity in human prostate epithelial cells remain unclear, impeding the implementation of new treatment strategies for cancer prevention and therapy. MEIS proteins are transcription factors that bind and direct HOX protein activity. MEIS proteins are putative tumor suppressors that are frequently silenced in aggressive forms of prostate cancer. Here we show that MEIS1 expression is sufficient to decrease proliferation and metastasis of prostate cancer cells in vitro and in vivo murine xenograft models. HOXB13 deletion demonstrates that the tumor-suppressive activity of MEIS1 is dependent on HOXB13. Integration of ChIP-seq and RNA-seq data revealed direct and HOXB13-dependent regulation of proteoglycans including decorin (DCN) as a mechanism of MEIS1-driven tumor suppression. These results define and underscore the importance of MEIS1-HOXB13 transcriptional regulation in suppressing prostate cancer progression and provide a mechanistic framework for the investigation of HOXB13 mutants and oncogenic cofactors when MEIS1/2 are silenced.

Shaping Chromatin States in Prostate Cancer by Pioneer Transcription Factors

The androgen receptor (AR) is a critical therapeutic target in prostate cancer that responds to antagonists in primary disease, but inevitably becomes reactivated, signaling onset of the lethal castration-resistant prostate cancer (CRPC) stage. Epigenomic investigation of the chromatin environment and interacting partners required for AR transcriptional activity has uncovered three pioneer factors that open up chromatin and facilitate AR-driven transcriptional programs. FOXA1, HOXB13, and GATA2 are required for normal AR transcription in prostate epithelial development and for oncogenic AR transcription during prostate carcinogenesis. AR signaling is dependent upon these three pioneer factors both before and after the clinical transition from treatable androgen-dependent disease to untreatable CRPC. Agents targeting their respective DNA binding or downstream chromatin-remodeling events have shown promise in preclinical studies of CRPC. AR-independent functions of FOXA1, HOXB13, and GATA2 are emerging as well. While all three pioneer factors exert effects that promote carcinogenesis, some of their functions may inhibit certain stages of prostate cancer progression. In all, these pioneer factors represent some of the most promising potential therapeutic targets to emerge thus far from the study of the prostate cancer epigenome.

Mutation HOXB13 c.853delT in Martinican prostate cancer patients

BACKGROUND

In Martinique, prostate cancer (Pca) incidence rates are nowadays among the highest worldwide with a high incidence of early-onset and familial forms. Despite the demonstration of a strong familial component, identification of the genetic basis for hereditary Pca is challenging. The HOXB13 germline variant G84E (rs138213197) was described in men of European descent with Pca risk.

METHODS

To investigate the potential involvement of HOXB13 mutations in Martinique, we performed sequencing of the HOXB13 coding regions of 46 index cases with early-onset Pca (before the age of 51). Additional breast cancers and controls were performed. All cancer cases analyzed in this study have been observed in the context of genetic counseling.

RESULTS

We identified a rare heterozygous germline variant c.853delT (p.Ter285Lysfs) rs77179853, reported only among patients of African ancestry with a minor allele frequency of 3.2%. This variant is a stop loss reported only among patients of African ancestry with a frequency of 0.2%.

CONCLUSION

In conclusion, we think that this study provides supplementary arguments that HOXB13 variants are involved in Pca.

HOX genes function in Breast Cancer development

Breast cancer develops in the mammary glands during mammalian adulthood and is considered the second most common type of human carcinoma and the most incident and mortal in the female population. In contrast to other human structures, the female mammary glands continue to develop after birth, undergoing various modifications during pregnancy, lactation and involution under the regulation of hormones and transcription factors, including those encoded by the HOX clusters (A, B, C, and D). Interestingly, HOX gene deregulation is often associated to breast cancer development. Within the HOXB cluster, 8 out of the 10 genes present altered expression levels in breast cancer with an impact in its aggressiveness and resistance to hormone therapy, which highlights the importance of HOXB genes as potential therapeutic targets used to overcome the limitations of tamoxifen-resistant cancer treatments. Here, we review the current state of knowledge on the role of HOX genes in breast cancer, specially focus on HOXB, discussing the causes and consequences of HOXB gene deregulation and their relevance as prognostic factors and therapeutic targets.

Paralogous HOX13 Genes in Human Cancers

Hox genes (HOX in humans), an evolutionary preserved gene family, are key determinants of embryonic development and cell memory gene program. Hox genes are organized in four clusters on four chromosomal loci aligned in 13 paralogous groups based on sequence homology (Hox gene network). During development Hox genes are transcribed, according to the rule of “spatio-temporal collinearity”, with early regulators of anterior body regions located at the 3’ end of each Hox cluster and the later regulators of posterior body regions placed at the distal 5’ end. The onset of 3’ Hox gene activation is determined by Wingless-type MMTV integration site family (Wnt) signaling, whereas 5’ Hox activation is due to paralogous group 13 genes, which act as posterior-inhibitors of more anterior Hox proteins (posterior prevalence). Deregulation of HOX genes is associated with developmental abnormalities and different human diseases. Paralogous HOX13 genes (HOX A13, HOX B13, HOX C13 and HOX D13) also play a relevant role in tumor development and progression. In this review, we will discuss the role of paralogous HOX13 genes regarding their regulatory mechanisms during carcinogenesis and tumor progression and their use as biomarkers for cancer diagnosis and treatment.

The Role of HOX Transcription Factors in Cancer Predisposition and Progression

Homeobox (HOX) transcription factors, encoded by a subset of homeodomain superfamily genes, play pivotal roles in many aspects of cellular physiology, embryonic development, and tissue homeostasis. Findings over the past decade have revealed that mutations in HOX genes can lead to increased cancer predisposition, and HOX genes might mediate the effect of many other cancer susceptibility factors by recognizing or executing altered genetic information. Remarkably, several lines of evidence highlight the interplays between HOX transcription factors and cancer risk loci discovered by genome-wide association studies, thereby gaining molecular and biological insight into cancer etiology. In addition, deregulated HOX gene expression impacts various aspects of cancer progression, including tumor angiogenesis, cell autophagy, proliferation, apoptosis, tumor cell migration, and metabolism. In this review, we will discuss the fundamental roles of HOX genes in cancer susceptibility and progression, highlighting multiple molecular mechanisms of HOX involved gene misregulation, as well as their potential implications in clinical practice.

HOXB13 interaction with MEIS1 modifies proliferation and gene expression in prostate cancer

BACKGROUND

The recurrent p.Gly84Glu germline mutation (G84E) in HOXB13 is consistently associated with prostate cancer (PCa), although the mechanisms underlying such linkage remain elusive. The majority of the PCa-associated HOXB13 mutations identified are localized to two conserved domains in HOXB13 that have been shown to mediate the interaction with MEIS cofactors belonging to the TALE family of homeodomain transcription factors. In this study, we sought to interrogate the biochemical and functional interactions between HOXB13 and MEIS in prostatic cells with a goal of defining how the HOXB13-MEIS complex impacts PCa pathobiology and define the extent to which the oncogenic activity of G84E is related to its effect on HOXB13-MEIS interaction/function.

METHODS

HOXB13 and MEIS paralog expression in prostate epithelial cells and PCa cell lines was characterized by qPCR and immunoblot analyses. HOXB13 and MEIS1 co-expression in human prostate tissue was confirmed by IHC, followed by co-IP mapping of HOXB13-MEIS1 interactions. Proliferation of the PCa cell line LAPC4 following shRNA-mediated knockdown of each gene or both genes was assessed using DNA- and metabolic-based assays. Transcriptional targets of HOXB13 and MEIS1 were identified by gene expression profiling and qPCR. Finally, protein stability of HOXB13 in the context of MEIS1 was determined using pulse-chase assays.

RESULTS

HOXB13 and MEIS1 are co-expressed and interact in prostate cells. Both of the putative MEIS interacting domains (MID) within HOXB13 were shown to be capable of mediating the interaction between HOXB13 and MEIS1 independently and such interactions were not influenced by the G84E mutation. The inhibitory effect of either HOXB13 or MEIS1 knockdown on cellular proliferation was augmented by knockdown of both genes, and MEIS1 knockdown abolished HOXB13-driven regulation of BCHE and TNFSF10 mRNA expression. Notably, we demonstrated that MEIS1 stabilized the HOXB13 protein in LAPC4 cells.

CONCLUSIONS

Our study provides evidence for functional HOXB13-MEIS1 interactions in PCa. MEIS1 may contribute to the cancer-promoting actions of HOXB13 in cellular proliferation and gene regulation by prolonging HOXB13 half-life. Our data demonstrates that G84E is not a loss-of-function mutation that interferes with HOXB13 stability or ability to interact with MEIS1.

Association of homeobox B13 (HOXB13) gene variants with prostate cancer risk in an Iranian population

Background: Prostate cancer is a complex condition in which both genetic and environmental factors concomitantly contribute to the tumor initiation and progression. Recently, HOXB13 has been proposed as a susceptibility gene for prostate cancer.

Objective: The present study was conducted to determine the existence of potential variations in HOXB13 gene in Iranian men with prostate cancer (PCa) compared to benign prostatic hyperplasia (BPH) cases.

Methods: HOXB13 genetic status was screened in 51 samples, including 21 blood and tissue of PCa cases, and compared to 30 cases affected by BPH using PCR/sequencing. Then, the existence of potential association was investigated between genomic DNA alterations in blood and tissue PCa specimens.

Results: Analysis of BPH tissues showed single nucleotide variations c.366C > T (rs) or c.513T > C (rs9900627) in exon 1, but not in exon 2. Evaluation of PCa tissues revealed 2 cases with both synonymous c.366C > T and c.513T > C variants and 2 cases with the synonymous c.366C > T variant in exon 1. The variants c.366C > T and c.513T > C, simultaneously or separately, were found in blood samples of PCa patients. The novel variant c.127A > G in exon 2 was detected in 1 PCa blood sample. Our analysis indicated a significant reciprocal correlation between HOXB13 mutation in the tissue and blood samples of PCa cases (p= 0.02).

Conclusion: The variants in exon 2 of HOXB13 may influence the risk of prostate cancer. Also, evaluation of HOXB13 mutation may be considered as a novel marker for screening PCa. Further investigations are warranted to evaluate the clinical significance of HOXB13 in Iranian population.

Epidemiology of prostate cancer in Asian countries

The incidence of prostate cancer has been increasing worldwide in recent years. The GLOBOCAN project showed that prostate cancer was the second most frequently diagnosed cancer and the fifth leading cause of cancer mortality among men worldwide in 2012. This trend has been growing even in Asian countries, where the incidence had previously been low. However, the accuracy of data about incidence and mortality as a result of prostate cancer in some Asian countries is limited. The cause of this increasing trend is multifactorial. One possible explanation is changes in lifestyles due to more Westernized diets. The incidence is also statistically biased by the wide implementation of early detection systems and the accuracy of national cancer registration systems, which are still immature in most Asian countries. Mortality rate decreases in Australia, New Zealand and Japan since the 1990s are possibly due to the improvements in treatment and/or early detection efforts employed. However, this rate is increasing in the majority of other Asian countries. Studies of latent and incidental prostate cancer provide less biased information. The prevalence of latent and incidental prostate cancer in contemporary Japan and Korea is similar to those in Western countries, suggesting the influence of lifestyle changes on carcinogenesis. Many studies reported evidence of both congenital and acquired risk factors for carcinogenesis of prostate cancer. Recent changes in the acquired risk factors might be associated with the increasing occurrence of prostate cancer in Asian countries. This trend could continue, especially in developing Asian countries.

Prostate Cancer Genomics: Recent Advances and the Prevailing Underrepresentation from Racial and Ethnic Minorities

Prostate cancer (CaP) is the most commonly diagnosed non-cutaneous cancer and the second leading cause of male cancer deaths in the United States. Among African American (AA) men, CaP is the most prevalent malignancy, with disproportionately higher incidence and mortality rates. Even after discounting the influence of socioeconomic factors, the effect of molecular and genetic factors on racial disparity of CaP is evident. Earlier studies on the molecular basis for CaP disparity have focused on the influence of heritable mutations and single-nucleotide polymorphisms (SNPs). Most CaP susceptibility alleles identified based on genome-wide association studies (GWAS) were common, low-penetrance variants. Germline CaP-associated mutations that are highly penetrant, such as those found in HOXB13 and BRCA2, are usually rare. More recently, genomic studies enabled by Next-Gen Sequencing (NGS) technologies have focused on the identification of somatic mutations that contribute to CaP tumorigenesis. These studies confirmed the high prevalence of ERG gene fusions and PTEN deletions among Caucasian Americans and identified novel somatic alterations in SPOP and FOXA1 genes in early stages of CaP. Individuals with African ancestry and other minorities are often underrepresented in these large-scale genomic studies, which are performed primarily using tumors from men of European ancestry. The insufficient number of specimens from AA men and other minority populations, together with the heterogeneity in the molecular etiology of CaP across populations, challenge the generalizability of findings from these projects. Efforts to close this gap by sequencing larger numbers of tumor specimens from more diverse populations, although still at an early stage, have discovered distinct genomic alterations. These research findings can have a direct impact on the diagnosis of CaP, the stratification of patients for treatment, and can help to address the disparity in incidence and mortality of CaP. This review examines the progress of understanding in CaP genetics and genomics and highlight the need to increase the representation from minority populations.

Targeted next generation sequencing identifies functionally deleterious germline mutations in novel genes in early-onset/familial prostate cancer

Considering that mutations in known prostate cancer (PrCa) predisposition genes, including those responsible for hereditary breast/ovarian cancer and Lynch syndromes, explain less than 5% of early-onset/familial PrCa, we have sequenced 94 genes associated with cancer predisposition using next generation sequencing (NGS) in a series of 121 PrCa patients. We found monoallelic truncating/functionally deleterious mutations in seven genes, including ATM and CHEK2, which have previously been associated with PrCa predisposition, and five new candidate PrCa associated genes involved in cancer predisposing recessive disorders, namely RAD51C, FANCD2, FANCI, CEP57 and RECQL4. Furthermore, using in silico pathogenicity prediction of missense variants among 18 genes associated with breast/ovarian cancer and/or Lynch syndrome, followed by KASP genotyping in 710 healthy controls, we identified "likely pathogenic" missense variants in ATM, BRIP1, CHEK2 and TP53. In conclusion, this study has identified putative PrCa predisposing germline mutations in 14.9% of early-onset/familial PrCa patients. Further data will be necessary to confirm the genetic heterogeneity of inherited PrCa predisposition hinted in this study.

Genetic factors influencing prostate cancer risk in Norwegian men

Norway has one of the highest rates of death due to prostate cancer (PCa) in the world. To assess the contribution of both common and rare single nucleotide variants (SNPs) to the prostate cancer burden in Norway, we assessed the frequency of the established prostate cancer susceptibility allele, HOXB13 G84E, as well as a series of validated, common PCa risk SNPs in a Norwegian PCa population of 779 patients. The G84E allele was observed in 2.3% of patients compared to 0.7% of control individuals, OR = 3.8, P = 1 × 10-4. While there was a trend toward an earlier age at diagnosis, overall the clinicopathologic features of PCa were not significantly different in G84E carriers and non-carriers. Evaluation of 32 established common risk alleles revealed significant associations of risk alleles at 13 loci, including SNPs at 8q24, and near TET2, SLC22A3, NKX3-1, CASC8, MYC, DAP2IP, MSMB, HNF1B, PPP1R14A, and KLK2/3. When the data for each SNP are combined into a genetic risk score (GRS), Norwegian men within the top decile of GRS have over 5-fold greater risk to be diagnosed with PCa than men with GRS in the lowest decile. These results indicate that risk alleles of HOXB13 and common variant SNPs are important components of inherited PCa risk in the Norwegian population, although these factors appear to contribute little to the malignancy's aggressiveness.

Computational Modeling of complete HOXB13 protein for predicting the functional effect of SNPs and the associated role in hereditary prostate cancer

The human HOXB13 gene encodes a 284 amino acid transcription factor belonging to the homeobox gene family containing a homeobox and a HoxA13 N-terminal domain. It is highly linked to hereditary prostate cancer, the majority of which is manifested as a result of a Single Nucleotide Polymorphism (SNP). In silico analysis of 95 missense SNP's corresponding to the non-homeobox region of HOXB13 predicted 21 nsSNP's to be potentially deleterious. Among 123 UTR SNPs analysed by UTRScan, rs543028086, rs550968159, rs563065128 were found to affect the UNR_BS, GY-BOX and MBE UTR signals, respectively. Subsequent analysis by PolymiRTS revealed 23 UTR SNPs altering the miRNA binding site. The complete HOXB13_M26 protein structure was modelled using MODELLER v9.17. Computational analysis of the 21 nsSNP's mapped into the HOXB13_M26 protein revealed seven nsSNP's (rs761914407, rs8556, rs138213197, rs772962401, rs778843798, rs770620686 and rs587780165) seriously resulting in a damaging and deleterious effect on the protein. G84E, G135E, and A128V resulted in increased, while, R215C, C66R, Y80C and S122R resulted in decreased protein stability, ultimately predicted to result in the altered binding patterns of HOXB13. While the genotype-phenotype based effects of nsSNP's were assessed, the exact biological and biochemical mechanism driven by the above predicted SNPs still needs to be extensively evaluated by in vivo and GWAS studies.

HOXB13 mutations and binding partners in prostate development and cancer: Function, clinical significance, and future directions

The recent and exciting discovery of germline HOXB13 mutations in familial prostate cancer has brought HOX signaling to the forefront of prostate cancer research. An enhanced understanding of HOX signaling, and the co-factors regulating HOX protein specificity and transcriptional regulation, has the high potential to elucidate novel approaches to prevent, diagnose, stage, and treat prostate cancer. Toward our understanding of HOX biology in prostate development and prostate cancer, basic research in developmental model systems as well as other tumor sites provides a mechanistic framework to inform future studies in prostate biology. Here we describe our current understanding of HOX signaling in genitourinary development and cancer, current clinical data of HOXB13 mutations in multiple cancers including prostate cancer, and the role of HOX protein co-factors in development and cancer. These data highlight numerous gaps in our understanding of HOX function in the prostate, and present numerous potentially impactful mechanistic and clinical opportunities for future investigation.

Inherited Predisposition to Prostate Cancer: From Gene Discovery to Clinical Impact

Family history of prostate cancer is one of the three most important risk factors for the disease in addition to age and race. Yet despite the recognition of this significant heritable component, it has been challenging to identify the genes associated with prostate cancer predisposition. Initial approaches focused on the collection of multiplex prostate cancer families. However, despite more than 20 years of linkage studies, few genes have been identified that account for a significant number of hereditary prostate cancer families. Our research team studied a large number of families with linkage evidence to chromosome 17q21-22 and ultimately identified a recurrent mutation in the HOXB13 gene. The HOXB13 G84E mutation occurs on a common haplotype consistent with a founder allele and worldwide, this allele accounts for ~5% of hereditary prostate cancer families. Current research from us and others focuses on the use of whole exome sequencing to identify rare cancer-causing alleles in early-onset and/or metastatic prostate cancer cases. The recent recognition of both germline and somatic alterations in DNA repair genes is important because mutation carriers appear to have a significant likelihood of developing aggressive/metastatic cancer.

Oncogenic mechanisms of HOXB13 missense mutations in prostate carcinogenesis

The recurrent germline mutation HOXB13 p.(Gly84Glu) (G84E) has recently been identified as a risk factor for prostate cancer. In a recent study, we have performed full sequencing of the HOXB13 gene in 462 Portuguese prostate cancer patients with early-onset and/or familial/hereditary disease, and identified two novel missense mutations, p.(Ala128Asp) (A128D) and p.(Phe240Leu) (F240L), that were predicted to be damaging to protein function. In the present work we aimed to investigate the potential oncogenic role of these mutations, comparing to that of the recurrent G84E mutation and wild-type HOXB13. We induced site-directed mutagenesis in a HOXB13 expression vector and established in vitro cell models of prostate carcinogenesis with stable overexpression of either the wild-type or the mutated HOXB13 variants. By performing in vitro assays we observed that, while the wild-type promotes proliferation, also observed with the F240L variant along with a decrease in apoptosis, the A128D mutation decreases apoptosis and promotes anchorage independent growth. No phenotypic impact was observed for the G84E mutation in the cell line model used. Our data show that specific HOXB13 mutations are involved in the acquisition of different cancer-associated capabilities and further support an oncogenic role for HOXB13 in prostate carcinogenesis.

Germline Variants of Prostate Cancer in Japanese Families

Prostate cancer (PC) is the second most common cancer in men. Family history is the major risk factor for PC. Only two susceptibility genes were identified in PC, BRCA2 and HOXB13. A comprehensive search of germline variants for patients with PC has not been reported in Japanese families. In this study, we conducted exome sequencing followed by Sanger sequencing to explore responsible germline variants in 140 Japanese patients with PC from 66 families. In addition to known susceptibility genes, BRCA2 and HOXB13, we identified TRRAP variants in a mutually exclusive manner in seven large PC families (three or four patients per family). We also found shared variants of BRCA2, HOXB13, and TRRAP from 59 additional small PC families (two patients per family). We identified two deleterious HOXB13 variants (F127C and G132E). Further exploration of the shared variants in rest of the families revealed deleterious variants of the so-called cancer genes (ATP1A1, BRIP1, FANCA, FGFR3, FLT3, HOXD11, MUTYH, PDGFRA, SMARCA4, and TCF3). The germline variant profile provides a new insight to clarify the genetic etiology and heterogeneity of PC among Japanese men.

Genetic variants in insulin-like growth factor binding protein-3 are associated with prostate cancer susceptibility in Eastern Chinese Han men

Background

Growing evidence has indicated that insulin-like growth factor binding protein-3 (IGFBP-3) polymorphisms are associated with altered risk of prostate cancer (PCa). However, few studies have been conducted in Chinese population to validate this association.

Materials and methods

Herein, we examined the association between genetic variants in the IGFBP-3 gene and PCa risk in the Chinese Han population based on a genome-wide association study (1,417 cases and 1,008 controls), and replicated three genetic variants loci in an independent case-control study (1,755 cases and 1,523 controls) using Sequenom platform. Logistic regression analyses were performed to estimate odds ratios (ORs) and 95% confidence intervals (95% CIs).

Results

We found that in the discovery stage, rs9691259 (OR =0.691, 95% CI: 0.587–0.814, P<0.001) and rs6950179 (OR =1.420, 95% CI: 1.201–1.677, P<0.001) were significantly associated with PCa risk, whereas rs2854744 showed a marginal association with PCa risk. In the replication stage, the association between rs9691259 and rs6950179 and PCa risk was not replicated, whereas rs2854744 conferred a significant association with PCa risk (OR =1.399, 95% CI: 1.010–1.937, P=0.043). After combining the two stages, we found that rs9691259, rs6950179, and rs2854744 were all significantly associated with PCa risk.

Conclusion

This study suggests that IGFBP-3 genetic variants are significantly associated with PCa risk in the Chinese population.

Prevalence and management of prostate cancer among East Asian men: Current trends and future perspectives

OBJECTIVES

Previously East Asian men had been considered less likely to develop or die of prostate cancer. Emerging research and the onset of prostate-specific antigen screening in East Asian countries suggests that this may not be the case. We sought to analyze epidemiology and molecular genetic data and recent trends in the management of prostate cancer among East Asian men.

METHODS AND MATERIALS

We performed literature searches using PubMed, Embase, and Google Scholar to examine current literature on prostate cancer in East Asian men. Additionally, articles were searched for further references related to the topic.

RESULTS

Recent studies have reported increasing incidence of prostate cancer identified in East Asian men. Prostate cancer mortality has increased and is currently the fourth leading cause of death among men in Shanghai, China. Although prostate cancer was considered less aggressive among East Asian men, studies suggest that it is similarly aggressive to prostate cancer in Western populations. Molecular markers such as the TEMPRESS:ERG fusion gene and PTEN loss may provide novel methods of screening East Asian men for prostate cancer. National-level guidelines for prostate cancer screening and management are only available in Japan.

CONCLUSIONS

The prevalence of prostate cancer in East Asian men is likely similar to that in Western male populations. East Asian men present at higher stages of prostate cancer, likely because of a lack of standardized screening protocols. Urologists in Western countries should screen East Asian men for prostate cancer using the same standards as used for Western men.

Large-scale association analysis in Asians identifies new susceptibility loci for prostate cancer

Genome-wide association studies (GWAS) have identified ∼100 genetic loci associated with prostate cancer risk. Less than a dozen of these loci were initially identified from GWAS in two Asian populations, likely because of smaller sample sizes of these individual GWAS in Asians. Here, we conduct a large-scale meta-analysis of two GWAS from the Japanese population (1,583 cases and 3,386 controls) and the Chinese population (1,417 cases and 1,008 controls), followed by replication in three independent sample sets. We identify two independent susceptibility loci for prostate cancer at 11p15.4 (rs12791447, P=3.59 × 10(-8); PPFIBP2) and 14q23.2 (rs58262369, P=6.05 × 10(-10); ESR2). The mRNA levels of PPFIBP2 and ESR2 are differentially expressed in prostate tumours and paired normal tissues. Our study adds two new loci to the limited number of prostate cancer risk-associated variants in Asians and provides important insight into potential biological mechanisms of prostate cancer.

Systematic enrichment analysis of potentially functional regions for 103 prostate cancer risk-associated loci

BACKGROUND

More than 100 prostate cancer (PCa) risk-associated single nucleotide polymorphisms (SNPs) have been identified by genome wide association studies (GWAS). However, the molecular mechanisms are unclear for most of these SNPs.

METHODS

All reported PCa risk-associated SNPs reaching the genome-wide significance level of P < 1 × 10(-7) (index SNPs), as well as SNPs in linkage disequilibrium (LD, r(2) ≥ 0.5) with them were cataloged. Genomic regions with potentially functional impact were also identified, including UCSC annotated coding regions (exon and snoRNA/miRNA) and regulatory regions, as well as binding regions for transcription factors (TFs), histone modifications (HMs), DNase I hypersensitivity (DHSs), and RNA Polymerase IIA (POLR2A) defined by ChIP-Seq in prostate cell lines and tissues. Enrichment analysis was performed to test whether PCa risk-associated SNPs are located in these functional regions more than expected.

RESULTS

A total of 103 PCa risk-associated index SNPs and 7,244 SNPs in LD with these index SNPs were cataloged. Genomic regions with potentially functional impact, grouped in 30 different categories of functionalities, were identified. Enrichment analysis indicated that genomic regions in the following 15 categories were enriched for the PCa risk-associated SNPs: exons, CpG regions, 6 TFs (AR, ERG, FOXA1, HOXB13, CTCF, and NR3C1), 5 HMs (H3K4me1, H3K4me2, H3K4me3, H3K27AC, and H3T11P), DHSs and POLR2A. In contrast, significantly fewer PCa risk SNPs were mapped to binding regions for H3K27me3, a repressive chromatin marker.

CONCLUSIONS

The PCa risk-associated SNPs discovered to date may affect PCa risk through multiple different mechanisms, especially by affecting binding regions of TFs/HMs.

Oxidative stress measured by thioredoxin reductase level as potential biomarker for prostate cancer

The aims of this study were to determine if Thioredoxin reductase (TR) is detected in the serum, and to establish the sensitivity and specificity of serum TR for diagnosing prostate cancer (PC). We assessed serum TR in 380 participants in the training cohort: 160 patients with PC, 120 with benign prostatic hyperplasia and 100 healthy individuals. The validation cohort comprised 320 participants: 120 with PC, 100 with BPH and 100 healthy individuals. TR was measured in serum by ELISA by independent researchers. The patients with PC were graded using the Gleason system. Receiver operating characteristic (ROC) curves were utilized to evaluate the accuracy of biomarkers to diagnose PC. The influence of serum levels of TR on tumor grade and metastasis was performed by binary logistic regression analysis. The median levels of serum TR in PC were significantly higher than that of healthy subjects and patients with BPH (P < 0.0001). Based on the ROC curve, the optimal cutoff value of serum TR levels as an indicator for auxiliary diagnosis of PC from BPH was projected to be 8.2 U/ml, which yielded a sensitivity of 81.8% and a specificity of 68.9%, with the area under the curve at 0.862 (95% CI, 0.821-0.903). Combined model (TR and PSA) showed a significantly greater discriminatory ability as compared with those markers alone. In regression analysis, after adjusting for other significant predictors, TR remained an independent metastasis predictor with an adjusted OR of 4.99 (95% CI, 2.64-8.09). Similarly, TR also was an independent High-grade tumors (HGT) predictor with an adjusted OR of 5.15 (95% CI, 2.52-9.14). Our study has demonstrated the additional benefit of TR measurement in the diagnosis of PC in the Chinese population. Further studies of the application of TR in this region may be beneficial.