Molecular aspects of hormone-independent prostate cancer

Serum testosterone as a biomarker for second prostatic biopsy in men with negative first biopsy for prostatic cancer and PSA>4ng/mL, or with PIN biopsy result

INTRODUCTION

Data from animal, clinical and prevention studies support the role of androgens in prostate cancer growth, proliferation and progression. Results of serum based epidemiologic studies in humans, however, have been inconclusive. The present study aims to define whether serum testosterone can be used as a predictor of a posi¬tive second biopsy in males considered for re-biopsy.

MATERIAL AND METHODS

The study included 320 men who underwent a prostatic biopsy in our department from October 2011 until June 2012. Total testosterone, free testos¬terone, bioavailable testosterone and prostate pathology were evaluated in all cases. Patients undergoing a second biopsy were identified and biopsy results were statistically analyzed.

RESULTS

Forty men (12.5%) were assessed with a second biopsy. The diagnosis of the second biopsy was High Grade Intraepithelial Neoplasia in 14 patients (35%) and Prostate Cancer in 12 patients (30%). The comparison of prostatic volume, total testosterone, sex hormone binding globulin, free testosterone, bioavailable testosterone and albumin showed that patients with cancer of the prostate had significantly greater levels of free testosterone (p=0.043) and bioavailable T (p=0.049).

CONCLUSION

In our study, higher free testosterone and bioavailable testosterone levels were associated with a cancer diagnosis at re-biopsy. Our results indicate a possible role for free and bioavailable testosterone in predicting the presence of prostate cancer in patients considered for re-biopsy.

The transcriptional programme of the androgen receptor (AR) in prostate cancer

The androgen receptor (AR) is essential for normal prostate and prostate cancer cell growth. AR transcriptional activity is almost always maintained even in hormone relapsed prostate cancer (HRPC) in the absence of normal levels of circulating testosterone. Current molecular techniques, such as chromatin-immunoprecipitation sequencing (ChIP-seq), have permitted identification of direct AR-binding sites in cell lines and human tissue with a distinct coordinate network evident in HRPC. The effectiveness of novel agents, such as abiraterone acetate (suppresses adrenal androgens) or enzalutamide (MDV3100, potent AR antagonist), in treating advanced prostate cancer underlines the on-going critical role of the AR throughout all stages of the disease. Persistent AR activity in advanced disease regulates cell cycle activity, steroid biosynthesis and anabolic metabolism in conjunction with regulatory co-factors, such as the E2F family, c-Myc and signal transducer and activator of transcription (STAT) transcription factors. Further treatment approaches must target these other factors.

Enzalutamide treatment in patients with metastatic castration-resistant prostate cancer progressing after chemotherapy and abiraterone acetate

OBJECTIVE

The aim of this study was to record prostate-specific antigen (PSA) response and overall survival (OS) for a group of metastatic castration-resistant prostate cancer (mCRPC) patients treated with enzalutamide following progression after abiraterone treatment in the post-chemotherapy setting.

MATERIAL AND METHODS

Twenty-four mCRPC patients with progression after abiraterone treatment following primary docetaxel therapy received enzalutamide 160 mg/day. The percentage PSA response was recorded following first line docetaxel, abiraterone and enzalutamide treatment. Fischer's exact test, Mann-Whitney U test and linear regression model were used to test for differences in PSA response.

RESULTS

All patients had a follow-up of at least 3 months. The median PSA response following 1 month of enzalutamide was -12% (range -56% to 76%), while the median best PSA response was -22% (-76% to 76%). Forty-six percent had a greater than 30% decrease in PSA. The PSA response to enzalutamide did not correlate with the number of prior cancer treatments (p = 0.57), time from diagnosis to mCRPC (p = 0.11) or prior response to docetaxel (p = 0.67). However, patients treated with second line cabazitaxel had an inferior PSA response to enzalutamide (p = 0.03), and there was a trend for the PSA response to abiraterone to correlate with the PSA response to the succeeding enzalutamide (B = 0.22, p = 0.05). The median OS was 4.8 months.

CONCLUSIONS

Previous abiraterone therapy is associated with a less marked fall in PSA following enzalutamide therapy in post-chemotherapy mCRPC patients compared with reported results in randomized trials. Larger prospective studies of sequencing are warranted.

DC-SCRIPT: AR and VDR regulator lost upon transformation of prostate epithelial cells

BACKGROUND

Nuclear receptors (NR), including the Androgen Receptor (AR) and the Vitamin D Receptor (VDR), play an important role in prostate cancer etiology. We recently found that DC-SCRIPT is a prognostic marker in breast cancer and a unique NR coregulator differentially regulating different classes of NRs. Here we investigated the importance of DC-SCRIPT in prostate cancer.

METHODS

DC-SCRIPT mRNA expression was measured by qPCR. Immunohistochemistry was used to detect DC-SCRIPT protein expression. The functional effects of DC-SCRIPT on the transcriptional activity of AR and VDR were assessed by luciferase reporter assays and qPCR assays on well-known AR and VDR target genes.

RESULTS

DC-SCRIPT mRNA was higher in normal than in corresponding malignant prostate tissue but could not be related to disease stage. DC-SCRIPT protein was found in morphologically normal prostate glands and in infiltrating immune cells. Strikingly, DC-SCRIPT protein expression was absent in malignant prostate epithelial tissue and prostate carcinoma cell lines. DC-SCRIPT protein expression appears to be lost prior to the basal cell marker HMW cytokeratin used in prostate carcinoma diagnostics. In addition, our data demonstrated that DC-SCRIPT repressed transcription mediated by wild-type and mutated AR while enhancing VDR mediated transcription. In addition, transient expression of DC-SCRIPT expression in prostate carcinoma cells strongly repressed cell growth.

CONCLUSIONS

DC-SCRIPT is a key regulator of nuclear receptors AR and VDR that play an opposite role in prostate cancer etiology and loss of DC-SCRIPT may be involved in the onset of prostate cancer.

Usefulness of preoperative serum testosterone as a predictor of extraprostatic extension and biochemical recurrence

Purpose

A great variety of studies on preoperative serum testosterone as a predictor of progression of prostate cancer have been reported recently. The purpose of this study was to investigate the relationship of preoperative serum testosterone levels in patients who underwent radical prostatectomy with prognostic factors.

Materials and Methods

Clinical data were collected from 60 patients who underwent radical prostatectomy. The 60 cases were divided into 2 groups according to their preoperative serum testosterone levels: group 1 (n=21), <3 ng/ml; group 2 (n=39), ≥3 ng/ml. The groups were compared according to prog-ression factors. Multivariate logistic regression analysis was performed to determine the correlation between biochemical recurrence and each variable.

Results

The incidence of extraprostatic invasions was significantly higher in group 1 with 13 cases in group 1 (61.9%) and 11 cases in group 2 (28.2%) (p=0.011). The incidence of biochemical recurrence was also significantly higher in group 1 with 5 cases in group 1 (23.8%) and 2 cases in group 2 (5.1%) (p=0.032). A low serum testosterone level (≤3 ng/ml) was associated with an increased risk of biochemical recurrence (odds ratio [OR], 13.64; 95% confidence interval [CI], 1.66 to 2.43; p=0.015) and an increased risk of extraprostatic invasions (OR, 4.96; 95% CI, 1.41 to 17.38; p=0.012).

Conclusions

The incidence rates of extraprostatic invasions and biochemical recurrence were significantly higher in the group with preoperative average serum testosterone of less than 3 ng/ml. Therefore, these results suggest that preoperative average serum testosterone will be useful in predicting postoperative prostate cancer progression.

Significance of Serum Testosterone for Prostate-Specific Antigen (PSA) Elevation and Prediction of Prostate Cancer in Patients with PSA Above 10 ng/ml

Purpose

Testosterone is essential for the prostate gland's normal growth and development and is also a possible risk factor for prostate cancer. This study's aim was to determine the significance of serum testosterone for prostate-specific antigen (PSA) elevation and prostate cancer prediction in high-risk men.

Materials and Methods

The study included 120 patients with PSA >10 ng/ml who underwent a transrectal-prostate biopsy. Serum testosterone, prostate volume, and PSA density (PSAD) were checked in all patients. Patients were divided into two groups, patients with and those without prostate cancer; and testosterone-related factors, prostate volume, PSA, PSAD, age, prostate cancer prediction rate, and cancer aggressiveness were evaluated.

Results

Thirty-five patients (30.2%) were confirmed as having prostate cancer. The average serum testosterone level in patients without and in those with prostate cancer was 452.25±154.62 ng/dl and 458.10±158.84 ng/dl, respectively; average PSA was 17.58±9.02 ng/ml and 18.62±6.53 ng/ml, respectively; and average age was 69.02±7.52 years and 70.69±7.02 years, respectively (p>0.05). Hypogonadal and eugonadal patients showed no significant difference in cancer prevalence (30.3% vs. 32.0%, respectively). The testosterone level did not differ significantly in patients with and those without prostate cancer in either hypogonadal or eugonadal men (p>0.05). Serum testosterone showed no correlation with PSA, PSAD, or age in either group (p>0.05) and was unrelated to prostate cancer risk or aggressiveness (p>0.05).

Conclusions

In our study's results, serum testosterone at the time of diagnosis was unrelated to PSA elevation, prostate cancer risk, and aggressiveness.