Association of Prostate Cancer Risk Variants with TMPRSS2:ERG Status: Evidence for Distinct Molecular Subtypes

Acquired copy number variation in prostate tumours: a review of common somatic copy number alterations, how they are formed and their clinical utility

Prostate cancer is one of the most commonly diagnosed cancers in men and unfortunately, disease will progress in up to a third of patients despite primary treatment. Currently, there is a significant lack of prognostic tests that accurately predict disease course; however, the acquisition of somatic chromosomal variation in the form of DNA copy number variants may help understand disease progression. Notably, studies have found that a higher burden of somatic copy number alterations (SCNA) correlates with more aggressive disease, recurrence after surgery and metastasis. Here we will review the literature surrounding SCNA formation, including the roles of key tumour suppressors and oncogenes (PTEN, BRCA2, NKX3.1, ERG and AR), and their potential to inform diagnostic and prognostic clinical testing to improve predictive value. Ultimately, SCNAs, or inherited germline alterations that predispose to SCNAs, could have significant clinical utility in diagnostic and prognostic tests, in addition to guiding therapeutic selection.

Unravelling the Role of Iroquois Homeobox 4 and its Interplay with Androgen Receptor in Prostate Cancer

Genome-wide association studies have linked Iroquois-Homeobox 4 (IRX4) as a robust expression quantitative-trait locus associated with prostate cancer (PCa) risk. However, the intricate mechanism and regulatory factors governing IRX4 expression in PCa remain poorly understood. Here, we unveil enrichment of androgen-responsive gene signatures in metastatic prostate tumors exhibiting heightened IRX4 expression. Furthermore, we uncover a novel interaction between IRX4 and the androgen receptor (AR) co-factor, FOXA1, suggesting that IRX4 modulates PCa cell behavior through AR cistrome alteration. Remarkably, we identified a distinctive short insertion-deletion polymorphism (INDEL), upstream of the IRX4 gene that differentially regulates IRX4 expression through the disruption of AR binding. This INDEL emerges as the most significant PCa risk-associated variant within the 5p15 locus, in a genetic analysis involving 82,591 PCa cases and 61,213 controls and was associated with PCa survival in patients undergoing androgen-deprivation therapy. These studies suggest the potential of this INDEL as a prognostic biomarker for androgen therapy in PCa and IRX4 as a potential therapeutic target in combination with current clinical management.

Germline Genetic Variants Associated with Somatic TMPRSS2:ERG Fusion Status in Prostate Cancer: A Genome-Wide Association Study

BACKGROUND

The prostate cancer subtype defined by the presence of TMPRSS2:ERG has been shown to be molecularly and epidemiologically distinct. However, few studies have investigated germline genetic variants associating with TMPRSS2:ERG fusion status.

METHODS

We performed a genome-wide association study with 396 TMPRSS2:ERG(+) cases, 390 TMPRSS2:ERG(-) cases, and 2,386 cancer-free controls from the Physicians' Health Study (PHS), the Health Professionals Follow-up Study (HPFS), and a Seattle-based Fred Hutchinson (FH) Cancer Center Prostate Cancer Study. We applied logistic regression models to test the associations between ∼5 million SNPs with TMPRSS2:ERG fusion status accounting for population stratification.

RESULTS

We did not identify genome-wide significant variants comparing the TMPRSS2:ERG(+) to the TMPRSS2:ERG(-) prostate cancer cases in the meta-analysis. When comparing TMPRSS2:ERG(+) prostate cancer cases with controls without prostate cancer, 10 genome-wide significant SNPs on chromosome 17q24.3 were observed in the meta-analysis. When comparing TMPRSS2:ERG(-) prostate cancer cases with controls without prostate cancer, two SNPs on chromosome 8q24.21 in the meta-analysis reached genome-wide significance.

CONCLUSIONS

We observed SNPs at several known prostate cancer risk loci (17q24.3, 1q32.1, and 8q24.21) that were differentially and exclusively associated with the risk of developing prostate tumors either with or without the gene fusion.

IMPACT

Our findings suggest that tumors with the TMPRSS2:ERG fusion exhibit a different germline genetic etiology compared with fusion negative cases.

Identification of F-Box/SPRY Domain-Containing Protein 1 (FBXO45) as a Prognostic Biomarker for TMPRSS2-ERG-Positive Primary Prostate Cancers

BACKGROUND

F-box/SPRY domain-containing protein 1 (FBXO45) plays a crucial role in the regulation of apoptosis via the ubiquitylation and degradation of specific targets. Recent studies indicate the prognostic potential of FBXO45 in several cancers. However, its specific role in prostate carcinoma remains unclear.

METHODS

A systematic analysis of FBXO45 mRNA expression in PCA was performed using The Cancer Genome Atlas database and a publicly available Gene Expression Omnibus progression PCA cohort. Subsequently, FBXO45 protein expression was assessed via immunohistochemical analysis of a comprehensive tissue microarray cohort. The expression data were correlated with the clinicopathological parameters and biochemical-free survival. The immunohistochemical analyses were stratified according to the TMPRSS2-ERG rearrangement status. To assess the impact of FBXO45 knockdown on the tumour proliferation capacity of cells and metastatic potential, transfection with antisense-oligonucleotides was conducted within a cell culture model.

RESULTS

FBXO45 mRNA expression was associated with adverse clinicopathological parameters in the TCGA cohort and was enhanced throughout progression to distant metastasis. FBXO45 was associated with shortened biochemical-free survival, which was pronounced for the TMPRSS2-ERG-positive tumours. In vitro, FBXO45 knockdown led to a significant reduction in migration capacity in the PC3, DU145 and LNCaP cell cultures.

CONCLUSIONS

Comprehensive expression analysis and functional data suggest FBXO45 as a prognostic biomarker in PCA.

Transcriptomes of Prostate Cancer with TMPRSS2:ERG and Other ETS Fusions

The most common somatic event in primary prostate cancer is a fusion between the androgen-related TMPRSS2 gene and the ERG oncogene. Tumors with these fusions, which occur early in carcinogenesis, have a distinctive etiology. A smaller subset of other tumors harbor fusions between TMPRSS2 and members of the ETS transcription factor family other than ERG. To assess the genomic similarity of tumors with non-ERG ETS fusions and those with fusions involving ERG, this study derived a transcriptomic signature of non-ERG ETS fusions and assessed this signature and ERG-related gene expression in 1,050 men with primary prostate cancer from three independent population-based and hospital-based studies. Although non-ERG ETS fusions involving ETV1, ETV4, ETV5, or FLI1 were individually rare, they jointly accounted for one in seven prostate tumors. Genes differentially regulated between non-ERG ETS tumors and tumors without ETS fusions showed similar differential expression when ERG tumors and tumors without ETS fusions were compared (differences explained: R2 = 69-77%), including ETS-related androgen receptor (AR) target genes. Differences appeared to result from similarities among ETS tumors rather than similarities among non-ETS tumors. Gene sets associated with ERG fusions were consistent with gene sets associated with non-ERG ETS fusions, including fatty acid and amino acid metabolism, an observation that was robust across cohorts.

IMPLICATIONS

Considering ETS fusions jointly may be useful for etiologic studies on prostate cancer, given that the transcriptome is profoundly impacted by ERG and non-ERG ETS fusions in a largely similar fashion, most notably genes regulating metabolic pathways.

Analysis of a large prostate cancer family identifies novel and recurrent gene fusion events providing evidence for inherited predisposition

There is strong interest in the characterisation of gene fusions and their use to enhance clinical practices in prostate cancer (PrCa). Significantly, ~50% of prostate tumours harbour a gene fusion. Inherited factors are thought to predispose to these events but, to date, only one study has investigated gene fusions in a familial context. Here, we examined the prevalence and diversity of gene fusions in 14 tumours from a single large PrCa family, PcTas9, using the TruSight® RNA Fusion Panel and Sanger sequencing validation. These fusions were then explored in The Cancer Genome Atlas (TCGA) PrCa data set (n = 494). Overall, 64.3% of PcTas9 tumours harboured a gene fusion, including known erythroblast transformation-specific (ETS) fusions involving ERG and ETV1, and two novel gene fusions, C19orf48:ETV4 and RYBP:FOXP1. Although 3' ETS genes were overexpressed in PcTas9 and TCGA tumour samples, 3' fusion of FOXP1 did not appear to alter its expression. In addition, PcTas9 fusion carriers were more likely to have lower-grade disease than noncarriers (p = 0.02). Likewise, TCGA tumours with high-grade disease were less likely to harbour fusions (p = 0.03). Our study further implicates an inherited predisposition to PrCa gene fusion events, which are associated with less aggressive tumours. This knowledge could lead to clinical strategies to predict men at risk for fusion-positive PrCa and, thus, identify patients who are more or less at risk of aggressive disease and/or responsive to particular therapies.

Association of Prediagnostic Blood Metabolomics with Prostate Cancer Defined by ERG or PTEN Molecular Subtypes

BACKGROUND

The TMPRSS2:ERG gene fusion and PTEN loss are two of the most common somatic molecular alterations in prostate cancer. Here, we investigated the association of prediagnostic-circulating metabolomics and prostate cancer defined by ERG or PTEN status to improve understanding of these etiologically distinct molecular prostate cancer subtypes.

METHODS

The study was performed among 277 prostate cancer cases with ERG status, 211 with PTEN status, and 294 controls nested in the Health Professionals Follow-up Study (HPFS) and the Physicians' Health Study (PHS). We profiled 223 polar and non-polar metabolites using LC-MS in prediagnostic plasma specimens. We applied enrichment analysis and multinomial logistic regression models to identify biological metabolite classes and individual metabolites associated with prostate cancer defined by ERG or PTEN status.

RESULTS

Compared with noncancer controls, sphingomyelin (P: 0.01), ceramide (P: 0.04), and phosphatidylethanolamine (P: 0.03) circulating levels were enriched among ERG-positive prostate cancer cases. Sphingomyelins (P: 0.02), ceramides (P: 0.005), and amino acids (P: 0.02) were enriched among tumors exhibiting PTEN-loss; unsaturated diacylglycerols (P: 0.003) were enriched among PTEN-intact cases; and unsaturated triacylglycerols were enriched among both PTEN-loss (P: 0.001) and PTEN-intact (P: 0.0001) cases. Although several individual metabolites identified in the above categories were nominally associated with ERG or PTEN-defined prostate cancer, none remained significant after accounting for multiple testing.

CONCLUSIONS

The molecular process of prostate carcinogenesis may be distinct for men with different metabolomic profiles.

IMPACT

These novel findings provide insights into the metabolic environment for the development of prostate cancer.

TMPRSS2-ERG fusion impacts anterior tumor location in men with prostate cancer

BACKGROUND

In prostate cancer (PCa), lack of androgen receptor (AR) regulated TMPRSS2-ETS-related gene (ERG) gene fusion (ERG^negative ) status has been associated with African American race; however, the implications of ERG status for the location of dominant tumors within the prostate remains understudied.

METHODS

An African American-enriched multiinstitutional cohort of 726 PCa patients consisting of both African American men (AAM; n = 254) and European American men (EAM; n = 472) was used in the analyses. Methods of categorical analysis were used. Messenger RNA (mRNA) expression differences between anterior and posterior tumor lesions were analyzed using Wilcoxon rank-sum tests with multiple comparison corrections.

RESULTS

Anti-ERG immunohistochemistry staining showed that the association between ERG status and anterior tumors is independent of race and is consistently robust for both AAM (ERG^negative 81.4% vs. ERG^positive 18.6%; p = .005) and EAM (ERG^negative 60.4% vs. ERG^positive 39.6%; p < .001). In a multivariable model, anterior tumors were more likely to be IHC-ERG^negative (odds ratio [OR]: 3.20; 95% confidence interval [CI]: 2.14-4.78; p < .001). IHC-ERG^negative were also more likely to have high-grade tumors (OR: 1.73; 95% CI: 1.06-2.82; p = .02). In the exploratory genomic analysis, mRNA expression of location-dependent genes is highly influenced by ERG status and African American race. However, tumor location did not impact the expression of AR or the major canonical AR-target genes (KLK3, AMACR, and MYC).

CONCLUSIONS

ERG^negative tumor status is the strongest predictor of anterior prostate tumors, regardless of race. Furthermore, AR expression and canonical AR signaling do not impact tumor location.

Family history of prostate cancer and the incidence of ERG- and phosphatase and tensin homolog-defined prostate cancer

Family history is among the strongest known risk factors for prostate cancer (PCa). Emerging data suggest molecular subtypes of PCa, including two somatic genetic aberrations: fusions of androgen-regulated promoters with ERG and, separately, phosphatase and tensin homolog (PTEN) loss. We examined associations between family history and incidence of these subtypes in 44,126 men from the prospective Health Professionals Follow-up Study. ERG and PTEN status were assessed by immunohistochemistry. Multivariable competing risks models were used to estimate hazard ratios (HR) and 95% confidence intervals (CI) for associations between self-reported family history of PCa and molecular subtypes of disease. Thirteen percent of men had a positive family history of PCa at baseline. During a median follow-up of 18.5 years, 5,511 PCa cases were diagnosed. Among them, 888 were assayed for ERG status (47% ERG-positive) and 715 were assayed for PTEN loss (14% PTEN null). Family history was more strongly associated with risk of ERG-negative (HR: 2.15; 95% CI: 1.71-2.70) than ERG-positive (HR: 1.49; 95% CI: 1.13-1.95) disease (p_{heterogeneity} : 0.04). The strongest difference was among men with an affected father (HR_ERG-negative : 2.09; 95% CI: 1.64-2.66; HR_ERG-positive : 1.30; 95% CI: 0.96-1.76; p_{heterogeneity} : 0.01). Family history of PCa was positively associated with both PTEN null (HR: 2.10; 95% CI: 1.26-3.49) and PTEN intact (HR: 1.72; 95% CI: 1.39-2.13) PCa (p_{heterogeneity} : 0.47). Our results indicate that PCa family history may be positively associated with PCa in all ERG and PTEN subtypes, suggesting a role of genetic susceptibility in their development. It is possible that ERG-negative disease could be especially associated with positive family history.

Association of germline genetic variants with TMPRSS2-ERG fusion status in prostate cancer

Introduction: Oncogenic activation of ERG resulting from TMPRSS2-ERG gene fusion is a key molecular genetic alteration in prostate cancer (CaP). The frequency of ERG fusion is variable by race; however, there are limited data available on germline polymorphisms associating with ERG fusion status. The goal of this study is to identify the inherited risk variants associating with ERG status of CaP.

Materials and Methods: SNP genotyping was performed on the Illumina platform using Infinium Oncoarray SNP chip on blood derived genomic DNA samples from 400 patients treated by radical prostatectomy at a single military institution. ERG status was determined in whole mounted prostate specimens by immuno-histochemistry (IHC) for ERG protein expression. Data analysis approaches included association analyses based on EMMAX and imputation by IMPUTE2. Imputed SNPs were validated by ddPCR.

Results: SNP genotyping analysis using imputation identified rs34349373 (p 4.68 × 10^-8) and rs2055272 (p 5.62 × 10^-8) in TBC1D22B to be significantly associated with ERG fusion status in index tumor and non-index tumor foci. Imputed SNP rs2055272 was further experimentally validated by ddPCR with 98.04% (100/102) concordance. Initial discovery analysis based on SNPs on Oncoarray SNP chip, showed significant (p 10^-5) association for SNPs (rs6698333, rs1889877, rs3798999, rs10215144, rs3818136, rs9380660 and rs1792695) with ERG fusion status. The study also replicated two previously known ERG fusion associated SNPs (rs11704416 in chromsome 22; rs16901979 in chromosome 8).

Conclusions: This study identified SNPs associated with ERG status of CaP.

Impact: The findings may contribute towards defining the underlying genetics of ERG positive and ERG negative CaP patients.

TMPRSS2 and COVID-19: Serendipity or Opportunity for Intervention?

TMPRSS2 is both the most frequently altered gene in primary prostate cancer and a critical factor enabling cellular infection by coronaviruses, including SARS-CoV-2. The modulation of its expression by sex steroids could contribute to the male predominance of severe infections, and given that TMPRSS2 has no known indispensable functions, and inhibitors are available, it is an appealing target for prevention or treatment of respiratory viral infections.

Proceedings of the fourth international molecular pathological epidemiology (MPE) meeting

An important premise of epidemiology is that individuals with the same disease share similar underlying etiologies and clinical outcomes. In the past few decades, our knowledge of disease pathogenesis has improved, and disease classification systems have evolved to the point where no complex disease processes are considered homogenous. As a result, pathology and epidemiology have been integrated into the single, unified field of molecular pathological epidemiology (MPE). Advancing integrative molecular and population-level health sciences and addressing the unique research challenges specific to the field of MPE necessitates assembling experts in diverse fields, including epidemiology, pathology, biostatistics, computational biology, bioinformatics, genomics, immunology, and nutritional and environmental sciences. Integrating these seemingly divergent fields can lead to a greater understanding of pathogenic processes. The International MPE Meeting Series fosters discussion that addresses the specific research questions and challenges in this emerging field. The purpose of the meeting series is to: discuss novel methods to integrate pathology and epidemiology; discuss studies that provide pathogenic insights into population impact; and educate next-generation scientists. Herein, we share the proceedings of the Fourth International MPE Meeting, held in Boston, MA, USA, on 30 May-1 June, 2018. Major themes of this meeting included 'integrated genetic and molecular pathologic epidemiology', 'immunology-MPE', and 'novel disease phenotyping'. The key priority areas for future research identified by meeting attendees included integration of tumor immunology and cancer disparities into epidemiologic studies, further collaboration between computational and population-level scientists to gain new insight on exposure-disease associations, and future pooling projects of studies with comparable data.

Aneuploidy drives lethal progression in prostate cancer

Aneuploidy, defined as chromosome gains and losses, is a hallmark of cancer. However, compared with other tumor types, extensive aneuploidy is relatively rare in prostate cancer. Thus, whether numerical chromosome aberrations dictate disease progression in prostate cancer patients is not known. Here, we report the development of a method based on whole-transcriptome profiling that allowed us to identify chromosome-arm gains and losses in 333 primary prostate tumors. In two independent cohorts (n = 404) followed prospectively for metastases and prostate cancer-specific death for a median of 15 years, increasing extent of tumor aneuploidy as predicted from the tumor transcriptome was strongly associated with higher risk of lethal disease. The 23% of patients whose tumors had five or more predicted chromosome-arm alterations had 5.3 times higher odds of lethal cancer (95% confidence interval, 2.2 to 13.1) than those with the same Gleason score and no predicted aneuploidy. Aneuploidy was associated with lethality even among men with high-risk Gleason score 8-to-10 tumors. These results point to a key role of aneuploidy in driving aggressive disease in primary prostate cancer.

Intratumoral Sterol-27-Hydroxylase (CYP27A1) Expression in Relation to Cholesterol Synthesis and Vitamin D Signaling and Its Association with Lethal Prostate Cancer

BACKGROUND

Higher intratumoral cholesterol synthesis is associated with a worse prognosis in prostate cancer. The vitamin D-regulated enzyme sterol-27-hydroxylase (CYP27A1) converts cholesterol to 27-hydroxycholesterol, potentially lowering intracellular cholesterol levels. We hypothesized that low CYP27A1 expression is associated with high cholesterol synthesis, low vitamin D signaling, and higher risk of lethal prostate cancer.

METHODS

In 404 patients from the prospective prostate cancer cohorts within the Health Professionals Follow-up Study (HPFS) and the Physicians' Health Study (PHS), we assessed intratumoral CYP27A1 expression and proxies of cholesterol synthesis using transcriptome profiling, prediagnostic plasma 25-hydroxyvitamin D [25(OH)D; n = 132], and intratumoral vitamin D receptor protein expression (VDR; n = 300). Patients were followed for metastases and prostate cancer mortality (lethal cancer; median follow-up, 15.3 years).

RESULTS

CYP27A1 expression was lower in tumors with higher Gleason grade and higher expression of cholesterol synthesis enzymes, including the second rate-limiting enzyme, SQLE. We did not detect consistent associations between CYP27A1 and 25(OH)D, VDR, or CYP24A1 mRNA expression. Lower CYP27A1 was associated with higher risk of lethal cancer in both cohorts, independent of SQLE [adjusted OR for lowest vs. highest quartile of CYP27A1, 2.64; 95% confidence interval (CI), 1.24-5.62]. This association was attenuated when additionally adjusting for Gleason grade (OR, 1.76; 95% CI, 0.75-4.17).

CONCLUSIONS

Low CYP27A1 expression was associated with higher cholesterol synthesis and a higher risk of lethal disease.

IMPACT

These observations further support the hypothesis that intratumoral cholesterol accumulation through higher synthesis and decreased catabolism is a feature of lethal prostate cancer.

Association between TMPRSS2:ERG fusion gene and the prostate cancer: systematic review and meta-analysis

Introduction

To identify the association between the TMPRSS2:ERG fusion gene, their variants and the onset of localized prostate cancer.

Material and methods

A systematic search strategy was carried out through MEDLINE, EMBASE, LILACS, CENTRAL and unpublished literature. We included randomized control trials, cohort, case-control and cross-sectional studies that involved patients >18 years-old assessing the association between TMPRSS2 fusion gene, its single nucleotide polymorphisms and prostate cancer. The primary outcome was prostate cancer defined by histology of the tumor coming from transrectal ultrasound guided biopsy, transurethral resection of the prostate or radical prostatectomy. We assessed the risk of bias with QUADAS2 and performed a meta-analysis with Stata 14.

Results

We found 241 records with the search strategies. After duplicates were removed, 18 studies were included in qualitative analysis and 15 studies in meta-analysis. All included studies that had no applicability concerns and low risk of bias for flow and timing. Nine studies had an unclear risk of bias for index and reference tests, since they did not describe the blinding assessment appropriately. Regarding the association between TMPRSS2:ERG and prostate cancer, we found an odds ratio (OR) 2.24 and a 95% confidence interval (CI) (1.29 to 3.91). Regarding the kind of sample, urine showed an OR 2.79 and a 95% CI (1.12 to 6.98) and when using a DNA molecular template, the OR was 3.55 with a 95% CI (1.08 to 11.65).

Conclusions

There was an association between TMPRSS2:ERG fusion gene with the diagnosis of prostate cancer, mainly in urine samples and DNA-based molecular templates. TMPRSS2:ERG might be used as the gold standard biomarker for diagnosis and stratification of PCa.

A Prospective Study of Aspirin Use and Prostate Cancer Risk by TMPRSS2:ERG Status

Background: In a case-control study, aspirin use was associated with a lower risk of a common prostate cancer molecular subtype, the TMPRSS2:ERG gene fusion. We sought to validate this finding in a prospective cohort.Methods: In the Health Professionals Follow-up Study, 49,395 men reported on aspirin use on biennial questionnaires and were followed for prostate cancer incidence over 23 years. TMPRSS2:ERG status was assessed by IHC for presence of ERG on archival tumor specimens for 912 patients with prostate cancer, of whom 48% were ERG-positive.Results: In multivariable models, we found no association between regular use of aspirin and risk of ERG-positive prostate cancer (HR, 1.02; 95% confidence interval, 0.85-1.23), nor any association with duration or frequency of aspirin use. In restricting to cases with either high Gleason grade or advanced stage disease, there remained no association with aspirin use.Conclusions: Data from this prospective study with repeated assessments of aspirin use do not support the hypothesis that aspirin use is associated with a lower risk of ERG-positive prostate cancer.Impact: Aspirin use is unlikely to lower the risk of this common molecular subtype of prostate cancer. However, there is emerging data supporting the role of other lifestyle and genetic factors underlying the development of the TMPRSS2:ERG fusion. Cancer Epidemiol Biomarkers Prev; 27(10); 1231-3. ©2018 AACR.

PRL‑3 increases the aggressive phenotype of prostate cancer cells in vitro and its expression correlates with high-grade prostate tumors in patients

The increased expression of phosphatase of regenerating liver-3 (PRL-3) has been shown to be associated with the aggressive and metastatic phenotype of different solid tumors. However, it is not known whether PRL-3 plays a similar role in the progression of prostate cancer (PCa). In this study, immunoblot analysis of androgen receptor (AR)-positive PCa lines (LNCaP and LNCaP-SF) revealed the constitutive cytoplasmic expression of PRL-3, and stimulation with R1881 (AR agonist) rapidly increased the nuclear translocation of PRL-3. The AR-negative cell lines exhibited negligible PRL-3 expression, and the ectopic overexpression of PRL-3 increased both the proliferative and invasive potential of PC3 and DU145 cells. In addition, we measured PRL-3 protein expression in human prostate tumor sections. A high-density prostate tumor microarray (TMA) was immunostained to assess whether PRL-3 expression and its subcellular localization (cytoplasmic and nuclear levels) is associated with the Gleason score (GS), Gleason grade (GG) and tumor stage (T-stage). Digital image analysis (DIA) revealed that PRL-3 expression was significantly higher in the malignant cores, as compared to the non-malignant areas. Increases in both total and nuclear PRL-3 levels were also associated with a higher GS and GG. Metastatic tumors (T4-stage) had lower cytoplasmic, but higher nuclear PRL-3 levels. Furthermore, the nuclear/cytoplasmic ratio for PRL-3 in the tumors graded as GS7 could effectively distinguish between indolent (3+4) and aggressive (4+3) disease. Thus, our experiments using PCa lines suggested that PRL-3 is an AR-regulated gene and its androgen-induced nuclear localization may increase the aggressive behavior of PCa cells. Furthermore, the digital analysis of immunostained tumor sections suggested that PRL-3 may be an effective biomarker of high-grade PCa, and its nuclear/cytoplasmic ratio may be used to distinguish between indolent vs. aggressive tumors.

Height, Obesity, and the Risk of TMPRSS2:ERG-Defined Prostate Cancer

Background: The largest molecular subtype of primary prostate cancer is defined by the TMPRSS2:ERG gene fusion. Few studies, however, have investigated etiologic differences by TMPRSS2:ERG status. Because the fusion is hormone-regulated and a man's hormonal milieu varies by height and obesity status, we hypothesized that both may be differentially associated with risk of TMPRSS2:ERG-defined disease.Methods: Our study included 49,372 men from the prospective Health Professionals Follow-up Study. Participants reported height and weight at baseline in 1986 and updated weight biennially thereafter through 2009. Tumor ERG protein expression (a TMPRSS2:ERG marker) was immunohistochemically assessed. We used multivariable competing risks models to calculate HRs and 95% confidence intervals (CIs) for the risk of ERG-positive and ERG-negative prostate cancer.Results: During 23 years of follow-up, we identified 5,847 incident prostate cancers, among which 913 were ERG-assayed. Taller height was associated with an increased risk of ERG-positive disease only [per 5 inches HR 1.24; 95% confidence interval (CI), 1.03-1.50; P_{heterogeneity} = 0.07]. Higher body mass index (BMI) at baseline (per 5 kg/m² HR 0.75; 95% CI, 0.61-0.91; P_{heterogeneity} = 0.02) and updated BMI over time (per 5 kg/m² HR 0.86; 95% CI, 0.74-1.00; P_{heterogeneity} = 0.07) were associated with a reduced risk of ERG-positive disease only.Conclusions: Our results indicate that anthropometrics may be uniquely associated with TMPRSS2:ERG-positive prostate cancer; taller height may be associated with greater risk, whereas obesity may be associated with lower risk.Impact: Our study provides strong rationale for further investigations of other prostate cancer risk factors that may be distinctly associated with subtypes. Cancer Epidemiol Biomarkers Prev; 27(2); 193-200. ©2017 AACR.

Prostate cancer risk regions at 8q24 and 17q24 are differentially associated with somatic TMPRSS2:ERG fusion status

Molecular and epidemiological differences have been described between TMPRSS2:ERG fusion-positive and fusion-negative prostate cancer (PrCa). Assuming two molecularly distinct subtypes, we have examined 27 common PrCa risk variants, previously identified in genome-wide association studies, for subtype specific associations in a total of 1221 TMPRSS2:ERG phenotyped PrCa cases. In meta-analyses of a discovery set of 552 cases with TMPRSS2:ERG data and 7650 unaffected men from five centers we have found support for the hypothesis that several common risk variants are associated with one particular subtype rather than with PrCa in general. Risk variants were analyzed in case-case comparisons (296 TMPRSS2:ERG fusion-positive versus 256 fusion-negative cases) and an independent set of 669 cases with TMPRSS2:ERG data was established to replicate the top five candidates. Significant differences (P < 0.00185) between the two subtypes were observed for rs16901979 (8q24) and rs1859962 (17q24), which were enriched in TMPRSS2:ERG fusion-negative (OR = 0.53, P = 0.0007) and TMPRSS2:ERG fusion-positive PrCa (OR = 1.30, P = 0.0016), respectively. Expression quantitative trait locus analysis was performed to investigate mechanistic links between risk variants, fusion status and target gene mRNA levels. For rs1859962 at 17q24, genotype dependent expression was observed for the candidate target gene SOX9 in TMPRSS2:ERG fusion-positive PrCa, which was not evident in TMPRSS2:ERG negative tumors. The present study established evidence for the first two common PrCa risk variants differentially associated with TMPRSS2:ERG fusion status. TMPRSS2:ERG phenotyping of larger studies is required to determine comprehensive sets of variants with subtype-specific roles in PrCa.