Paras B. Singh

SOX9 Elevation in the Prostate Promotes Proliferation and Cooperates with PTEN Loss to Drive Tumor Formation

Dysregulation of tissue development pathways can contribute to cancer initiation and progression. In murine embryonic prostate epithelia, the transcription factor SOX9 is required for proper prostate development. In this study, we examined a role for SOX9 in prostate cancer in mouse and human. In Pten and Nkx3.1 mutant mice, cells with increased levels of SOX9 appeared within prostate epithelia at early stages of neoplasia, and higher expression correlated with progression at all stages of disease. In transgenic mice, SOX9 overexpression in prostate epithelia increased cell proliferation without inducing hyperplasia. In transgenic mice that were also heterozygous for mutant Pten, SOX9 overexpression quickened the induction of high-grade prostate intraepithelial neoplasia. In contrast, Sox9 attenuation led to a decrease proliferating prostate epithelia cells in normal and homozygous Pten mutant mice with prostate neoplasia. Analysis of a cohort of 880 human prostate cancer samples showed that SOX9 expression was associated with increasing Gleason grades and higher Ki67 staining. Our findings identify SOX9 as part of a developmental pathway that is reactivated in prostate neoplasia where it promotes tumor cell proliferation.

A potential paradox in prostate adenocarcinoma progression: Oestrogen as the initiating driver

One in 10 men in the developed world will present with prostate cancer (CaP), and in an ageing population developing strategies for its chemoprevention or treatment is of significance. For decades, androgen ablation has remained the frontline treatment for CaP that is no longer organ-confined and thus deemed surgically inoperable. Orchidectomy or drug-induced reduction of serum testosterone levels with the consequent removal of growth-promoting effects in the prostate is the driving rationale for this regimen. However, resistance often develops within a few months to years and androgen-insensitive tumours develop. In recent years, there has been an increasing focus on chemoprevention with agents such as finasteride being employed to reduce the risk of developing CaP. Significantly, such chemoprevention strategies are also based on 5alpha-reductase inhibition thus reducing intraprostatic dihydrotestosterone levels. Although there may be an overall reduction in CaP incidence in cohorts using such chemoprevention, in a subset of users who do develop this pathology there results a more aggressive, higher-grade disease. There have also been suggestions regarding the protective role of androgens against high-grade CaP. This leads to the intriguing notion that 17beta-oestradiol (E2) may be an initiating driver of CaP; in fact, in old studies in which CaP was induced in rodents, E2 often accelerated the effect of the carcinogen. Might certain chemoprevention strategies or androgen ablation result in a systemic feedback loop in hormone synthesis or metabolism? If so, elevated serum E2 levels could result in its increased conversion to genotoxic catechol oestrogens in target tissues such as the prostate. Paradoxically, if E2 were to be an initiating factor in CaP, anti-oestrogens might be an overlooked treatment or chemoprevention strategy.

Quantification of phase I / II metabolizing enzyme gene expression and polycyclic aromatic hydrocarbon-DNA adduct levels in human prostate

Studies of migrant populations suggest that dietary and/or environmental factors play a crucial role in the etiology of prostatic adenocarcinoma (CaP). The human prostate consists of the peripheral zone (PZ), transition zone (TZ), and central zone (CZ); CaP occurs most often in the PZ.

Constitutive expression of bioactivating enzymes in normal human prostate suggests a capability to activate pro‐carcinogens to DNA‐damaging metabolites

The constitutive bioactivating capacity of human prostate may play a role in determining risk of adenocarcinoma developing in this tissue. Expression of candidate enzymes that convert exogenous and/or endogenous agents into reactive DNA‐damaging species would suggest the potential to generate initiating events in prostate cancer (CaP).

Prostate Cancer Tumour Features on Template Prostate-mapping Biopsies: Implications for Focal Therapy

Background Focal therapy is being offered as a viable alternative for men with localised prostate cancer (PCa), but it is unclear which men may be suitable. Objective To determine the proportion of men with localised PCa who are potentially suitable for focal therapy. Design, setting, and participants Our institutional transperineal template prostate-mapping (TTPM) biopsy registry of 377 men from 2006 to 2010 identified 291 consecutive men with no prior treatment. Intervention TTPM biopsies using a 5-mm sampling frame. Outcome measurements and statistical analysis Suitability for focal therapy required the cancer to be (1) unifocal, (2) unilateral, (3) bilateral/bifocal with at least one neurovascular bundle avoided, or (4) bilateral/multifocal with one dominant index lesion and secondary lesions with Gleason ≤3 + 3 and cancer core involvement ≤3 mm. Binary logistic regression modelling was used to determine variables predictive for focal therapy suitability. Results and limitations The median age was 61 yr, and the median prostate-specific antigen was 6.8 ng/ml. The median total was 29 cores, with a median of 8 positive cores. Of 239 of 291 men with cancer, 29% (70 men), 60% (144 men), and 8% (20 men) had low-, intermediate-, and high-risk PCa, respectively. Ninety-two percent (220 men) were suitable for one form of focal therapy: hemiablation (22%, 53 men), unifocal ablation (31%, 73 men), bilateral/bifocal ablation (14%, 33 men), and index lesion ablation (26%, 61 men). Binary logistic regression modelling incorporating transrectal biopsy parameters showed no statistically significant predictive variable. When incorporating TTPM parameters, only T stage was a significant negative predictor for suitability (p = 0.001) (odds ratio: 0.001 [95% confidence interval, 0.000–0.048]). Limitations of the study include potential selection bias caused by tertiary referral practise and lack of long-term results on focal therapy efficacy. Conclusions Focal therapy requires an accurate tool to localise individual cancer lesions. When such a test, TTPM biopsy, was applied to men with low- and intermediate-risk PCa, most of the men were suitable for a tissue preservation strategy.

The Prevalence of Clinically Significant Prostate Cancer According to Commonly Used Histological Thresholds in Men Undergoing Template Prostate Mapping Biopsies

PURPOSE Transrectal prostate biopsies are inaccurate and, thus, the prevalence of clinically significant prostate cancer in men undergoing biopsy is unknown. We determined the ability of different histological thresholds to denote clinically significant cancer in men undergoing a more accurate biopsy, that of transperineal template prostate mapping. MATERIALS AND METHODS In this multicenter, cross-sectional cohort of men who underwent template prostate mapping biopsies between May 2006 and January 2012, 4 different thresholds of significance combining tumor grade and burden were used to measure the consequent variation with respect to the prevalence of clinically significant disease. RESULTS Of 1,203 men 17% (199) had no previous biopsy, 38% (455) had a prior negative transrectal ultrasound biopsy, 24% (289) were on active surveillance and 21% (260) were seeking risk stratification. Mean patient age was 63.5 years (SD 7.6) and median prostate specific antigen was 7.4 ng/ml (IQR 5.3-10.5). Overall 35% of the patients (424) had no cancer detected. The prevalence of clinically significant cancer varied between 14% and 83% according to the histological threshold used, in particular between 30% and 51% among men who had no previous biopsy, between 14% and 27% among men who had a prior negative biopsy, between 36% and 74% among men on active surveillance, and between 47% and 83% among men seeking risk stratification. CONCLUSIONS According to template prostate mapping biopsy between 1 in 2 and 1 in 3 men have prostate cancer that is histologically defined as clinically significant. This suggests that the commonly used thresholds may be set too low.

Quantified gene expression levels for phase I/II metabolizing enzyme and estrogen receptor levels in benign prostate from cohorts designated as high-risk (UK) versus low-risk (India) for adenocarcinoma at this organ site: a preliminary study.

Risk of clinically significant prostate adenocarcinoma (CaP) varies worldwide, although there is a uniform prevalence of latent disease. A hormone-responsive tissue, the prostate possesses the metabolizing capacity to biotransform a variety of environmental procarcinogens or endogenous hormones. Whether such metabolizing capacity or estrogen receptor (ER) status underlies these demographic differences in susceptibility to CaP remains unclear. With appropriate ethical permission, verified-benign tissues were obtained following transurethral resection of the prostate from a high-risk region (n = 12 UK-resident Caucasians) and a typically low-risk region (n = 14 India-resident Asians). Quantitative gene expression analysis was employed for cytochrome P450 (CYP)1B1, N-acetyltransferase (NAT)1, NAT2, catechol-O-methyl transferase (COMT), sulfotransferase (SULT)1A1, ERalpha, ERbeta and aromatase (CYP19A1). To quantify the presence or absence of CYP1B1, ERalpha or ERbeta, and to identify their in situ localization, immunohistochemistry was carried out. The two cohorts had reasonably well-matched serum levels of prostate-specific antigen or hormones. Expression levels for the candidate genes investigated were similar. However, clear differences in protein levels for CYP1B1 and ERbeta were noted. Staining for CYP1B1 tended to be nuclear-associated in the basal glandular epithelial cells, and in UK-resident Caucasian tissues was present at a higher (P = 0.006) level compared with that from India-resident Asians. In contrast, a higher level of positive ERbeta staining was noted in prostates from India-resident Asians. These study findings point to differences in metabolizing capacity and ER status in benign prostate tissues that might modulate susceptibility to the emergence of clinically significant CaP in demographically distinct populations.

Risk of prostate cancer after detection of isolated high-grade prostatic intraepithelial neoplasia (HGPIN) on extended core needle biopsy: a UK hospital experience

BackgroundHigh-grade prostatic intraepithelial neoplasia (HGPIN) is a precursor lesion to prostate cancer (CaP). UK-based studies examining the occurrence of isolated HGPIN and subsequent risk of CaP are lacking. Our aim was to assess the occurrence of HGPIN in a regional UK population and to determine whether in a retrievable cohort of such patients that had repeat extended core biopsies, there was an elevated risk of CaP.MethodsA retrospective analysis of the pathology database was conducted at our institution (Lancashire Teaching Hospitals NHS Foundation Trust) for prostate biopsies recorded between January 2001 and December 2005 (all extended core biopsies). Those patients with isolated HGPIN on 1st set of biopsies were identified and, their clinical characteristics and pathological findings from subsequent biopsies (if any) were determined. The risk of CaP on subsequent biopsies based on presenting baseline PSA was stratified.ResultsOf 2,192 biopsied patients, there were 88 cases of isolated HGPIN of which 67 patients underwent one or more repeat biopsies. In this repeat-biopsy group, 28 CaP diagnoses were made. Age at first biopsy (P < 0.001), higher mean baseline prostate-specific antigen (PSA) (P < 0.005) and higher mean change in PSA (P < 0.05) were predictive of CaP detection on repeat biopsies. PSA ranges and their associated predictive values for cancer were: 0 to 5 ng/ml – 11%; 5 to 10 ng/ml – 34%; 10 to 20 ng/ml – 50%; and > 20 ng/ml – 87.5%.ConclusionBased on our results, we recommend delaying the 1st repeat biopsy at low PSA range but to have a shorter interval to repeat biopsies at intermediate and higher PSA ranges.

Transperineal template prostate-mapping biopsies: an evaluation of different protocols in the detection of clinically significant prostate cancer

To determine whether modified transperineal template prostate‐mapping (TTPM) biopsy protocols, altering the template or the biopsy density, have sensitivity and negative predictive value (NPV) equal to full 5‐mm TTPM.

Elevated Oestrogen Receptor Splice Variant ERαΔ5 Expression in Tumour-adjacent Hormone-responsive Tissue

Susceptibility to prostate or endometrial cancer is linked with obesity, a state of oestrogen excess. Oestrogen receptor (ER) splice variants may be responsible for the tissue-level of ER activity. Such micro-environmental regulation may modulate cancer initiation and/or progression mechanisms. Real-time reverse transcriptase (RT) polymerase chain reaction (PCR) was used to quantitatively assess the levels of four ER splice variants (ERαΔ3, ERαΔ5, ERβ2 and ERβ5), plus the full-length parent isoforms ERα and ERβ1, in high-risk [tumour-adjacent prostate (n = 10) or endometrial cancer (n = 9)] vs. low-risk [benign prostate (n = 12) or endometrium (n = 9)], as well as a comparison of UK (n = 12) vs. Indian (n = 15) benign prostate. All three tissue groups expressed the ER splice variants at similar levels, apart from ERαΔ5. This splice variant was markedly raised in all of the tumour-adjacent prostate samples compared to benign tissues. Immunofluorescence analysis for ERβ2 in prostate tissue demonstrated that such splice variants are present in comparable, if not greater, amounts as the parent full-length isoform. This small pilot study demonstrates the ubiquitous nature of ER splice variants in these tissue sites and suggests that ERαΔ5 may be involved in progression of prostate adenocarcinoma.