Genomic Characterization of Prostatic Basal Cell Carcinoma.

Basal cell carcinoma (BCC) of the prostate is a rare tumor. Compared with the more common acinar adenocarcinoma (AAC) of the prostate, BCCs show features of basal cell differentiation and are thought to be biologically distinct from AAC. The spectrum of molecular alterations of BCC has not been comprehensively described, and genomic studies are lacking. Herein, whole genome sequencing was performed on archival formalin-fixed, paraffin-embedded specimens of two cases with BCC. Prostatic BCCs were characterized by an overall low copy number and mutational burden. Recurrent copy number loss of chromosome 16 was observed. In addition, putative driver gene alterations in KIT, DENND3, PTPRU, MGA, and CYLD were identified. Mechanistically, depletion of the CYLD protein resulted in increased proliferation of prostatic basal cells in vitro. Collectively, these studies show that prostatic BCC displays distinct genomic alterations from AAC and highlight a potential role for loss of chromosome 16 in the pathogenesis of this rare tumor type.

Single-cell atlas of epithelial and stromal cell heterogeneity by lobe and strain in the mouse prostate.

BACKGROUND: Evaluating the complex interplay of cell types in the tissue microenvironment is critical to understanding the origin and progression of diseases in the prostate and potential opportunities for intervention. Mouse models are an essential tool to investigate the molecular and cell-type-specific contributions of prostate disease at an organismal level. While there are well-documented differences in the extent, timing, and nature of disease development in various genetically engineered and exposure-based mouse models in different mouse strains and prostate lobes within each mouse strain, the underlying molecular phenotypic differences in cell types across mouse strains and prostate lobes are incompletely understood. METHODS: In this study, we used single-cell RNA-sequencing (scRNA-seq) methods to assess the single-cell transcriptomes of 6-month-old mouse prostates from two commonly used mouse strains, friend virus B/NIH jackson (FVB/NJ) (N = 2) and C57BL/6J (N = 3). For each mouse, the lobes of the prostate were dissected (anterior, dorsal, lateral, and ventral), and individual scRNA-seq libraries were generated. In situ and pathological analyses were used to explore the spatial and anatomical distributions of novel cell types and molecular markers defining these cell types. RESULTS: Data dimensionality reduction and clustering analysis of scRNA-seq data revealed that basal and luminal cells possessed strain-specific transcriptomic differences, with luminal cells also displaying marked lobe-specific differences. Gene set enrichment analysis comparing luminal cells by strain showed enrichment of proto-Oncogene targets in FVB/NJ mice. Additionally, three rare populations of epithelial cells clustered independently of strain and lobe: one population of luminal cells expressing Foxi1 and components of the vacuolar ATPase proton pump (Atp6v0d2 and Atp6v1g3), another population expressing Psca and other stem cell-associated genes (Ly6a/Sca-1, Tacstd2/Trop-2), and a neuroendocrine population expressing Chga, Chgb, and Syp. In contrast, stromal cell clusters, including fibroblasts, smooth muscle cells, endothelial cells, pericytes, and immune cell types, were conserved across strain and lobe, clustering largely by cell type and not by strain or lobe. One notable exception to this was the identification of two distinct fibroblast populations that we term subglandular fibroblasts and interstitial fibroblasts based on their strikingly distinct spatial distribution in the mouse prostate. CONCLUSIONS: Altogether, these data provide a practical reference of the transcriptional profiles of mouse prostate from two commonly used mouse strains and across all four prostate lobes.

Hormonal patterns in men with prediabetes and diabetes in NHANES III: possible links with prostate cancer.

PURPOSE: Pathways involving sex hormones and insulin-like growth factors (IGFs) have been proposed to explain, in part, the lower risk of prostate cancer among men with diabetes. To gain insights into potential biological mechanisms we explored differences in serum concentrations of sex hormones and IGFs across the trajectory from normoglycemia to prediabetes to poorly controlled diabetes. METHODS: Using cross-sectional data from the National Health and Nutrition Examination Survey III we examined differences in levels of circulating sex hormones, sex hormone-binding globulin (SHBG), IGF-1, and IFG-binding protein 3 (IGFBP-3), according to diabetes status: no diabetes [n = 648], prediabetes [n = 578], undiagnosed diabetes [n = 106], well-controlled diabetes [n = 42], and poorly controlled diabetes [n = 56]. Adjusted geometric mean concentrations were derived using multivariable linear regression, adjusted for age, race, and other lifestyle factors. RESULTS: Total testosterone concentrations were lower among prediabetics (4.89 ng/mL, 95% confidence interval (CI) 4.95-5.21) than men without prediabetes/diabetes (5.29 ng/mL, 95% CI 5.06-5.53) but did not reduce further across diabetes groups. Concentrations of estradiol, estimated free testosterone, SHGB, IGF-1, and IGFBP-3 did not differ. While the ratio of IGF-1 to IGFBP-3 was lower among men with prediabetics and undiagnosed diabetes than men without prediabetes/diabetes, there was no trend across groups. A positive trend for the ratio of estradiol-to-testosterone levels was observed across groups (p trend = 0.045). CONCLUSION: Our findings do not provide clear support for either an androgen driven or IGF-driven pathway for the inverse association between diabetes and prostate cancer risk.

Association of Serum Carotenoids and Retinoids with Intraprostatic Inflammation in Men without Prostate Cancer or Clinical Indication for Biopsy in the Placebo Arm of the Prostate Cancer Prevention Trial.

Non-supplemental carotenoids and retinol may potentiate antioxidant and anti-inflammatory mechanisms. Chronic intraprostatic inflammation is linked to prostate carcinogenesis. We investigated the association of circulating carotenoids and retinol with intraprostatic inflammation in benign tissue. We included 235 men from the Prostate Cancer Prevention Trial placebo arm who had a negative end-of-study biopsy, most (92.8%) done without clinical indication. α-carotene, ß-carotene, ß-cryptoxanthin, lycopene, and retinol were assessed by high-performance liquid chromatography using pooled year 1 and 4 serum. Presence and extent of intraprostatic inflammation in benign tissue was assessed in 3 (of 6-10) biopsy cores. Logistic (any core with inflammation vs none) and polytomous logistic (some or all cores with inflammation vs none) regression was used to estimate odds ratios (OR) and 95% confidence intervals (CI) of intraprostatic inflammation by concentration tertile adjusting for age, race, prostate cancer family history, and serum cholesterol. None of the carotenoids or retinol was associated with intraprostatic inflammation, except ß-cryptoxanthin, which appeared to be positively associated with any core with inflammation [vs none, T2: OR (95% CI) = 2.67 (1.19, 5.99); T3: 1.80 (0.84, 3.82), P-trend = 0.12]. These findings suggest that common circulating carotenoids and retinol are not useful dietary intervention targets for preventing prostate cancer via modulating intraprostatic inflammation.

Phenotypic characterization of two novel cell line models of castration-resistant prostate cancer.

BACKGROUND: Resistance to androgen deprivation therapies is a major driver of mortality in advanced prostate cancer. Therefore, there is a need to develop new preclinical models that allow the investigation of resistance mechanisms and the assessment of drugs for the treatment of castration-resistant prostate cancer. METHODS: We generated two novel cell line models (LAPC4-CR and VCaP-CR) which were derived by passaging LAPC4 and VCaP cells in vivo and in vitro under castrate conditions. We performed detailed transcriptomic (RNA-seq) and proteomic analyses (SWATH-MS) to delineate expression differences between castration-sensitive and castration-resistant cell lines. Furthermore, we characterized the in vivo and in vitro growth characteristics of these novel cell line models. RESULTS: The two cell line derivatives LAPC4-CR and VCaP-CR showed castration-resistant growth in vitro and in vivo which was only minimally inhibited by AR antagonists, enzalutamide, and bicalutamide. High-dose androgen treatment resulted in significant growth arrest of VCaP-CR but not in LAPC4-CR cells. Both cell lines maintained AR expression, but exhibited distinct expression changes on the mRNA and protein level. Integrated analyses including data from LNCaP and the previously described castration-resistant LNCaP-abl cells revealed an expression signature of castration resistance. CONCLUSIONS: The two novel cell line models LAPC4-CR and VCaP-CR and their comprehensive characterization on the RNA and protein level represent important resources to study the molecular mechanisms of castration resistance.

The association of sex steroid hormone concentrations with non-alcoholic fatty liver disease and liver enzymes in US men.

BACKGROUND & AIMS: This study aimed to analyse the association of sex hormone levels with liver enzyme levels and non-alcoholic fatty liver disease (NAFLD) in a nationally representative sample of men. METHODS: A total of 919 men from the US National Health and Nutrition Examination Study (NHANES) III were included in this cross-sectional analysis of data from 1988 to 1991. We used existing data on serum total and free testosterone, total and free estradiol, androstanediol glucuronide (AAG) and sex steroid-binding globulin (SHBG), and estimated their associations with aspartate aminotransferase (AST), and alanine aminotransferase (ALT) and NAFLD, as determined using ultrasound, after adjusting for possible confounders including age, race, smoking, alcohol, physical activity, waist circumference and steroid hormones. RESULTS: Lower total testosterone (TT) and higher free estradiol were associated with higher odds of NAFLD after adjusting for confounders including the other sex hormones. Lower TT was associated with higher odds of elevated AST, but not ALT. Free testosterone, total estradiol, SHBG and AAG were not associated with NAFLD or liver enzymes. CONCLUSIONS: This study supports an inverse association between TT concentration and NAFLD in men independent of other sex hormones (SHBG, AAG and estradiol) and known risk factors, such as obesity, age and lifestyle. Exploration of whether TT might be a non-invasive marker for NAFLD diagnosis is warranted.

The association between serum sex steroid hormone concentrations and intraprostatic inflammation in men without prostate cancer and irrespective of clinical indication for biopsy in the placebo arm of the Prostate Cancer Prevention Trial.

BACKGROUND: Intraprostatic inflammation is an emerging prostate cancer risk factor. Estrogens are pro-inflammatory while androgens are anti-inflammatory. Thus, we investigated whether serum sex steroid hormone concentrations are associated with intraprostatic inflammation to inform mechanistic links among hormones, inflammation, and prostate cancer. METHODS: We conducted a cross-sectional study among 247 men in the placebo arm of the Prostate Cancer Prevention Trial who had a negative end-of-study biopsy, most (92.7%) performed without clinical indication per trial protocol. Serum estradiol, estrone, and testosterone were previously measured by immunoassay in pooled baseline and Year 3 serum. Free estradiol and free testosterone were calculated. Inflammation was visually assessed (median of three prostate biopsy cores per man). Polytomous or logistic regression was used to estimate the odds ratio (OR) and 95% confidence interval (CI) of some or all cores inflamed (both vs none) or any core inflamed (vs none) by hormone tertile, adjusting for age, race, and family history. We evaluated effect modification by waist circumference and body mass index (BMI). RESULTS: In all, 51.4% had some and 26.3% had all cores inflamed. Free (P-trend = .11) but not total estradiol was suggestively inversely associated with all cores inflamed. In men with waist circumference greater than or equal to 102 cm (P-trend = .021) and BMI ≥ 27.09 kg/m2 (P-trend = .0037) free estradiol was inversely associated with any core inflamed. Estrone was inversely associated with all cores inflamed (T3: OR = 0.36, 95% CI 0.14-0.95, P-trend = .036). Total (T3: OR = 1.91, 95% CI 0.91-4.02, P-trend = .11) and free (T3: OR = 2.19, 95% CI 1.01-4.74, P-trend = .05) testosterone were positively associated with any core inflamed, especially free testosterone in men with waist circumference less than 102 cm (T3: OR = 3.51, 95% CI 1.03-12.11, P-trend = .05). CONCLUSIONS: In this first study in men without prostate cancer and irrespective of clinical indication for biopsy, contrary to the hypothesis, circulating estrogens appeared to be inversely associated, especially in heavy men, whereas androgens appeared to be positively associated with intraprostatic inflammation.

Bisulfite-converted duplexes for the strand-specific detection and quantification of rare mutations.

The identification of mutations that are present at low frequencies in clinical samples is an essential component of precision medicine. The development of molecular barcoding for next-generation sequencing has greatly enhanced the sensitivity of detecting such mutations by massively parallel sequencing. However, further improvements in specificity would be useful for a variety of applications. We herein describe a technology (BiSeqS) that can increase the specificity of sequencing by at least two orders of magnitude over and above that achieved with molecular barcoding and can be applied to any massively parallel sequencing instrument. BiSeqS employs bisulfite treatment to distinguish the two strands of molecularly barcoded DNA; its specificity arises from the requirement for the same mutation to be identified in both strands. Because no library preparation is required, the technology permits very efficient use of the template DNA as well as sequence reads, which are nearly all confined to the amplicons of interest. Such efficiency is critical for clinical samples, such as plasma, in which only tiny amounts of DNA are often available. We show here that BiSeqS can be applied to evaluate transversions, as well as small insertions or deletions, and can reliably detect one mutation among >10,000 wild-type molecules.

Trichomonas vaginalis infection and prostate-specific antigen concentration: Insights into prostate involvement and prostate disease risk.

BACKGROUND: The protist Trichomonas vaginalis causes a common, sexually transmitted infection and has been proposed to contribute to the development of chronic prostate conditions, including benign prostatic hyperplasia and prostate cancer. However, few studies have investigated the extent to which it involves the prostate in the current antimicrobial era. We addressed this question by investigating the relation between T. vaginalis antibody serostatus and serum prostate-specific antigen (PSA) concentration, a marker of prostate infection, inflammation, and/or cell damage, in young, male, US military members. METHODS: We measured T. vaginalis serum IgG antibodies and serum total PSA concentration in a random sample of 732 young, male US active duty military members. Associations between T. vaginalis serostatus and PSA were investigated by linear regression. RESULTS: Of the 732 participants, 341 (46.6%) had a low T. vaginalis seropositive score and 198 (27.0%) had a high score, with the remainder seronegative. No significant differences were observed in the distribution of PSA by T. vaginalis serostatus. However, slightly greater, nonsignificant differences were observed when men with high T. vaginalis seropositive scores were compared with seronegative men, and when higher PSA concentrations were examined (≥0.70 ng/mL). Specifically, 42.5% of men with high seropositive scores had a PSA concentration greater than or equal to 0.70 ng/mL compared with 33.2% of seronegative men (adjusted P = .125). CONCLUSIONS: Overall, our findings do not provide strong support for prostate involvement during T. vaginalis infection, although our suggestive positive findings for higher PSA concentrations do not rule out this possibility entirely. These suggestive findings may be relevant for prostate condition development because higher early- to mid-life PSA concentrations have been found to predict greater prostate cancer risk later in life.

Comprehensive Evaluation of Programmed Death-Ligand 1 Expression in Primary and Metastatic Prostate Cancer.

Antibodies targeting the programmed cell death protein 1/programmed death-ligand 1 (PD-L1) interaction have shown clinical activity in multiple cancer types. PD-L1 protein expression is a clinically validated predictive biomarker of response for such therapies. Prior studies evaluating the expression of PD-L1 in primary prostate cancers have reported highly variable rates of PD-L1 positivity. In addition, limited data exist on PD-L1 expression in metastatic castrate-resistant prostate cancer (mCRPC). Here, we determined PD-L1 protein expression by immunohistochemistry using a validated PD-L1-specific antibody (SP263) in a large and representative cohort of primary prostate cancers and prostate cancer metastases. The study included 539 primary prostate cancers comprising 508 acinar adenocarcinomas, 24 prostatic duct adenocarcinomas, 7 small-cell carcinomas, and a total of 57 cases of mCRPC. PD-L1 positivity was low in primary acinar adenocarcinoma, with only 7.7% of cases showing detectable PD-L1 staining. Increased levels of PD-L1 expression were noted in 42.9% of small-cell carcinomas. In mCRPC, 31.6% of cases showed PD-L1-specific immunoreactivity. In conclusion, in this comprehensive evaluation of PD-L1 expression in prostate cancer, PD-L1 expression is rare in primary prostate cancers, but increased rates of PD-L1 positivity were observed in mCRPC. These results will be important for the future clinical development of programmed cell death protein 1/PD-L1-targeting therapies in prostate cancer.

Sustained influence of infections on prostate-specific antigen concentration: An analysis of changes over 10 years of follow-up.

BACKGROUND: To extend our previous observation of a short-term rise in prostate-specific antigen (PSA) concentration, a marker of prostate inflammation and cell damage, during and immediately following sexually transmitted and systemic infections, we examined the longer-term influence of these infections, both individually and cumulatively, on PSA over a mean of 10 years of follow-up in young active duty U.S. servicemen. METHODS: We measured PSA in serum specimens collected in 1995-7 (baseline) and 2004-6 (follow-up) from 265 men diagnosed with chlamydia (CT), 72 with gonorrhea (GC), 37 with non-chlamydial, non-gonococcal urethritis (NCNGU), 58 with infectious mononucleosis (IM), 91 with other systemic or non-genitourinary infections such as varicella; and 125-258 men with no infectious disease diagnoses in their medical record during follow-up (controls). We examined the influence of these infections on PSA change between baseline and follow-up. RESULTS: The proportion of men with any increase in PSA (>0 ng/mL) over the 10-year average follow-up was significantly higher in men with histories of sexually transmitted infections (CT, GC, and NCNGU; 67.7% vs 60.8%, P = 0.043), systemic infections (66.7% vs 54.4%, P = 0.047), or any infections (all cases combined; 68.5% vs 54.4%, P = 0.003) in their military medical record compared to controls. CONCLUSIONS: While PSA has been previously shown to rise during acute infection, these findings demonstrate that PSA remains elevated over a longer period. Additionally, the overall infection burden, rather than solely genitourinary-specific infection burden, contributed to these long-term changes, possibly implying a role for the cumulative burden of infections in prostate cancer risk.

Cost implications of PSA screening differ by age.

BACKGROUND: Multiple guidelines seek to alter rates of prostate-specific antigen (PSA)-based prostate cancer screening. The costs borne by payers associated with PSA-based screening for men of different age groups-including the costs of screening and subsequent diagnosis, treatment, and adverse events-remain uncertain. We sought to develop a model of PSA costs that could be used by payers and health care systems to inform cost considerations under a range of different scenarios. METHODS: We determined the prevalence of PSA screening among men aged 50 and higher using 2013-2014 data from a large, multispecialty group, obtained reimbursed costs associated with screening, diagnosis, and treatment from a commercial health plan, and identified transition probabilities for biopsy, diagnosis, treatment, and complications from the literature to generate a cost model. We estimated annual total costs for groups of men ages 50-54, 55-69, and 70+ years, and varied annual prostate cancer screening prevalence in each group from 5 to 50% and tested hypothetical examples of different test characteristics (e.g., true/false positive rate). RESULTS: Under the baseline screening patterns, costs of the PSA screening represented 10.1% of the total costs; costs of biopsies and associated complications were 23.3% of total costs; and, although only 0.3% of all screen eligible patients were treated, they accounted for 66.7% of total costs. For each 5-percentage point decrease in PSA screening among men aged 70 and older for a single calendar year, total costs associated with prostate cancer screening decreased by 13.8%. For each 5-percentage point decrease in PSA screening among men 50-54 and 55-69 years old, costs were 2.3% and 7.3% lower respectively. CONCLUSIONS: With constrained financial resources and with national pressure to decrease use of clinically unnecessary PSA-based prostate cancer screening, there is an opportunity for cost savings, especially by focusing on the downstream costs disproportionately associated with screening men 70 and older.

Insight into infection-mediated prostate damage: Contrasting patterns of C-reactive protein and prostate-specific antigen levels during infection.

BACKGROUND: To investigate mechanisms underlying our previous observation of a large rise in serum prostate-specific antigen, a marker of prostate pathology, during both sexually transmitted and systemic infections, we measured serum high-sensitivity C-reactive protein (hsCRP), a marker of systemic inflammation, in our previous case-control study of young, male US military members and compared our findings to those for PSA. METHODS: We measured hsCRP before and during infection for 299 chlamydia, 112 gonorrhea, and 59 non-chlamydial, non-gonococcal urethritis (NCNGU) cases; before and after infection for 55 infectious mononucleosis (IM) and 90 other systemic/non-genitourinary cases; and for 220-256 controls. RESULTS: Only gonorrhea cases were significantly more likely to have a large hsCRP rise (≥1.40 mg/L or ≥239%) during infection than controls (P < 0.01). However, gonorrhea, IM, and other systemic/non-genitourinary cases were more likely to have a rise of any magnitude up to one year post-diagnosis than controls (p = 0.038-0.077). CONCLUSIONS: These findings, which differ from those for PSA, suggest distinct mechanisms of elevation for hsCRP and PSA, and support both direct (eg, prostate infection) and indirect (eg, systemic inflammation-mediated prostate cell damage) mechanisms for PSA elevation. Future studies should explore our PSA findings further for their relevance to both prostate cancer screening and risk.

Molecular evidence that invasive adenocarcinoma can mimic prostatic intraepithelial neoplasia (PIN) and intraductal carcinoma through retrograde glandular colonization.

Prostate cancer often manifests as morphologically distinct tumour foci and is frequently found adjacent to presumed precursor lesions such as high-grade prostatic intraepithelial neoplasia (HGPIN). While there is some evidence to suggest that these lesions can be related and exist on a pathological and morphological continuum, the precise clonal and temporal relationships between precursor lesions and invasive cancers within individual tumours remain undefined. Here, we used molecular genetic, cytogenetic, and histological analyses to delineate clonal, temporal, and spatial relationships between HGPIN and cancer lesions with distinct morphological and molecular features. First, while confirming the previous finding that a substantial fraction of HGPIN lesions associated with ERG-positive cancers share rearrangements and overexpression of ERG, we found that a significant subset of such HGPIN glands exhibit only partial positivity for ERG. This suggests that such ERG-positive HGPIN cells either rapidly invade to form adenocarcinoma or represent cancer cells that have partially invaded the ductal and acinar space in a retrograde manner. To clarify these possibilities, we used ERG expression status and TMPRSS2-ERG genomic breakpoints as markers of clonality, and PTEN deletion status to track temporal evolution of clonally related lesions. We confirmed that morphologically distinct HGPIN and nearby invasive cancer lesions are clonally related. Further, we found that a significant fraction of ERG-positive, PTEN-negative HGPIN and intraductal carcinoma (IDC-P) lesions are most likely clonally derived from adjacent PTEN-negative adenocarcinomas, indicating that such PTEN-negative HGPIN and IDC-P lesions arise from, rather than give rise to, the nearby invasive adenocarcinoma. These data suggest that invasive adenocarcinoma can morphologically mimic HGPIN through retrograde colonization of benign glands with cancer cells. Similar clonal relationships were also seen for intraductal carcinoma adjacent to invasive adenocarcinoma. These findings represent a potentially undervalued indicator of pre-existing invasive prostate cancer and have significant implications for prostate cancer diagnosis and risk stratification.

Infectious mononucleosis, other infections and prostate-specific antigen concentration as a marker of prostate involvement during infection.

Although Epstein-Barr virus has been detected in prostate tissue, no associations have been observed with prostate cancer in the few studies conducted to date. One possible reason for these null findings may be use of cumulative exposure measures that do not inform the timing of infection, i.e., childhood versus adolescence/early adulthood when infection is more likely to manifest as infectious mononucleosis (IM). We sought to determine the influence of young adult-onset IM on the prostate by measuring prostate-specific antigen (PSA) as a marker of prostate inflammation/damage among U.S. military members. We defined IM cases as men diagnosed with IM from 1998 to 2003 (n = 55) and controls as men without an IM diagnosis (n = 255). We selected two archived serum specimens for each participant, the first collected after diagnosis for cases and one randomly selected from 1998 to 2003 for controls (index), as well as the preceding specimen (preindex). PSA was measured in each specimen. To explore the specificity of our findings for prostate as opposed to systemic inflammation, we performed a post hoc comparison of other infectious disease cases without genitourinary involvement (n = 90) and controls (n = 220). We found that IM cases were more likely to have a large PSA rise than controls (≥ 20 ng/mL: 19.7% versus 8.8%, p = 0.027; ≥ 40% rise: 25.7% versus 9.4%, p = 0.0021), as were other infectious disease cases (25.7% versus 14.0%, p = 0.020; 27.7% versus 18.0%, p = 0.092). These findings suggest that, in addition to rising because of prostate infection, PSA may also rise because of systemic inflammation, which could have implications for PSA interpretation in older men.

GSTP1 Loss results in accumulation of oxidative DNA base damage and promotes prostate cancer cell survival following exposure to protracted oxidative stress.

BACKGROUND: Epigenetic silencing of glutathione S-transferase π (GSTP1) is a hallmark of transformation from normal prostatic epithelium to adenocarcinoma of the prostate. The functional significance of this loss is incompletely understood. The present study explores the effects of restored GSTP1 expression on glutathione levels, accumulation of oxidative DNA damage, and prostate cancer cell survival following oxidative stress induced by protracted, low dose rate ionizing radiation (LDR). METHODS: GSTP1 protein expression was stably restored in LNCaP prostate cancer cells. The effect of GSTP1 restoration on protracted LDR-induced oxidative DNA damage was measured by GC-MS quantitation of modified bases. Reduced and oxidized glutathione levels were measured in control and GSTP1 expressing populations. Clonogenic survival studies of GSTP1- transfected LNCaP cells after exposure to protracted LDR were performed. Global gene expression profiling and pathway analysis were performed. RESULTS: GSTP1 expressing cells accumulated less oxidized DNA base damage and exhibited decreased survival compared to control LNCaP-Neo cells following oxidative injury induced by protracted LDR. Restoration of GSTP1 expression resulted in changes in modified glutathione levels that correlated with GSTP1 protein levels in response to protracted LDR-induced oxidative stress. Survival differences were not attributable to depletion of cellular glutathione stores. Gene expression profiling and pathway analysis following GSTP1 restoration suggests this protein plays a key role in regulating prostate cancer cell survival. CONCLUSIONS: The ubiquitous epigenetic silencing of GSTP1 in prostate cancer results in enhanced survival and accumulation of potentially promutagenic DNA adducts following exposure of cells to protracted oxidative injury suggesting a protective, anti-neoplastic function of GSTP1. The present work provides mechanistic backing to the tumor suppressor function of GSTP1 and its role in prostate carcinogenesis.

Association between serum 25-hydroxyvitamin D and serum sex steroid hormones among men in NHANES.

BACKGROUND: Recent literature suggests that high circulating vitamin D may increase prostate cancer risk. Although the mechanism through which vitamin D may increase risk is unknown, vitamin D concentration could influence circulating sex steroid hormones that may be associated with prostate cancer; an alternate explanation is that it could be associated with prostate-specific antigen (PSA) concentration causing detection bias. OBJECTIVE: We examined whether serum vitamin D concentration was associated with sex steroid hormone and PSA concentrations in a cross-sectional analysis of men in the National Health and Nutrition Examination Surveys (NHANES). DESIGN: Testosterone, oestradiol, sex hormone-binding globulin (SHBG), androstanediol glucuronide, and 25-hydroxyvitamin D (25(OH)D) were measured in serum from men aged 20 and older participating in NHANES III (n = 1315) and NHANES 2001-2004 (n = 318). Hormone concentrations were compared across 25(OH)D quintiles, adjusting for age, race/ethnicity, body fat percentage, and smoking. PSA concentration was estimated by 25(OH)D quintile in 4013 men from NHANES 2001-2006. RESULTS: In NHANES III, higher testosterone (quintile (Q) 1 = 17·2, 95% confidence interval (CI) = 16·1-18·6; Q5 = 19·6, 95% CI = 18·7-20·6 nmol/l, P-trend = 0·0002) and SHBG (Q1 = 33·8, 95% CI = 30·8-37·0; Q5 = 38·4, 95% CI = 35·8-41·2 nmol/l, P-trend = 0·0005) were observed with increasing 25(OH)D. Similar results were observed in NHANES 2001-2004. PSA concentration was not associated with serum 25(OH)D (P-trend = 0·34). CONCLUSION: Results from these nationally representative studies support a positive association between serum 25(OH)D and testosterone and SHBG. The findings support an indirect mechanism through which vitamin D may increase prostate cancer risk, and suggest the link to prostate cancer is not due to PSA-detection bias.

Inflammation in prostate carcinogenesis.

About 20% of all human cancers are caused by chronic infection or chronic inflammatory states. Recently, a new hypothesis has been proposed for prostate carcinogenesis. It proposes that exposure to environmental factors such as infectious agents and dietary carcinogens, and hormonal imbalances lead to injury of the prostate and to the development of chronic inflammation and regenerative 'risk factor' lesions, referred to as proliferative inflammatory atrophy (PIA). By developing new experimental animal models coupled with classical epidemiological studies, genetic epidemiological studies and molecular pathological approaches, we should be able to determine whether prostate cancer is driven by inflammation, and if so, to develop new strategies to prevent the disease.

Circulating total testosterone and PSA concentrations in a nationally representative sample of men without a diagnosis of prostate cancer.

BACKGROUND: The association between serum sex steroid hormones and PSA in a general population has not been described. METHODS: Included were 378 men aged 40-85 years who participated in the National Health and Nutrition Examination Survey in 2001-2004, who did not have a prostate cancer diagnosis, and had not had a recent biopsy, rectal examination, cystoscopy, or prostate infection or inflammation. Serum total PSA, total testosterone, androstanediol glucuronide (3α-diol-G), estradiol, and sex hormone binding globulin (SHBG) concentrations were previously measured. Free testosterone was estimated by mass action. We applied sampling weights and calculated geometric mean PSA concentration by hormone quintiles adjusting for age and race/ethnicity, and also for body mass index, waist circumference, smoking, diabetes, and mutually for hormones. We estimated the OR of PSA ≥2.5 ng/ml per hormone quintile using logistic regression. RESULTS: Geometric mean PSA increased across testosterone quintiles after age and race/ethnicity (Q1: 0.80, Q5: 1.14 ng/ml; P-trend = 0.002) and multivariable (Q1: 0.79, Q5: 1.16 ng/ml; P-trend = 0.02) adjustment; patterns were similar for free testosterone and 3α-diol-G. SHBG was inversely associated with PSA only after multivariable adjustment (Q1: 1.32, Q5: 0.82 nmol/L; P-trend = 0.01). Estradiol and PSA were not associated. The OR of PSA ≥2.5 ng/ml was 1.54 (95% CI 1.18-2.01) per testosterone quintile after age and race/ethnicity adjustment, and 1.78 (95% CI 1.16-2.73) after multivariable adjustment. CONCLUSIONS: In this nationally representative sample, men with higher testosterone had higher PSA even after taking into account other hormones and modifiable factors. Men with higher SHBG had lower PSA, but only after multivariable adjustment.