Androgen deprivation induces bladder histological abnormalities and dysfunction via TGF-β in orchiectomized mature rats

Prediction of recurrence of non-muscle invasive bladder cancer: The role of androgen receptor and miRNA-2909

AIM

The exact role of androgen receptor (AR) and miR-2909 in non-muscle invasive bladder cancer (NMIBC) remains controversial. Our aim is to assess the relationship between NMIBC recurrences with AR expression and miRNA-2909.

PATIENTS AND METHODS

This prospective controlled cohort study included 99 male patients with NMIBC (Ta-T1) who were treated by transurethral resection and 50 male patients as healthy control. We quantified blood AR messenger RNA variants 1 and 2 (AR1, AR2) and plasma miRNA-2909 with real-time quantitative polymerase chain reaction and the full length AR (AR-FL) using enzyme-linked immunosorbent assay in serum samples. In addition, AR1 and AR2 expression in tumor as well as normal tissues were analyzed. Kaplan-Meier survival curves and multivariate Cox analysis were used to identify independent predictors of recurrence-free survival.

RESULTS

In comparison to control group, blood AR1, AR2, and serum AR-FL expression were significantly lower in the NMIBC group compared to plasma miRNA-2909 expression that was significantly higher in the control group. Blood AR1, AR2, and serum AR-FL were significantly correlated with higher tumor stage (pT1) while plasma miRNA-2909 was not. The median survival time (months) was significantly better for higher blood AR1 (34 vs. 21; P = 0.03), lower plasma miRNA-2909 (29 vs. 8; P <0.001), lower AR2 in normal tissues (32 vs. 22; P = 0.007). On multivariate analysis, serum free testosterone (hazards ratio [HR]: 8.9; 95% CI: 1.8-45.1; P = 0.008), serum AR1 (HR: 0.5; 95% CI: 0.3-0.9; P = 0.02), and plasma miRNA-2909 (HR: 5.8; 95% CI: 2.3-14.7; P = 0.0002), and tissue AR2 (HR: 2.6; 95% CI: 1.4-4.7; P = 0.002) were independent predictor for NMIBC recurrence.

CONCLUSIONS

Blood and tissue levels of AR expression have a potential significant effect on NMIBC recurrence. Further studies are recommended to establish its exact role.

Androgen receptor in bladder cancer: A promising therapeutic target

There has been a significant progress in the treatment of metastatic urothelial carcinoma in the last few years with the advent of immunotherapy after a long gap of no drug approvals for over 4 decades. While immunotherapy with checkpoint inhibitors has revolutionized the treatment of urothelial carcinoma, unfortunately, only a minority of patients respond to immunotherapy. Treatment options for patients who do not respond and/or progress on immunotherapy are very limited and overall prognosis remains dismal in metastatic urothelial carcinoma. The first targeted therapy targeting the fibroblast growth factor receptor (FGFR) was recently approved for bladder cancer, but it is effective only in select patients harboring the FGFR2 and FGFR 3 mutations. Antibody drug conjugates like enfortumab vedotin have shown promising activity in clinical trials. Development of novel targeted therapies remains an area of investigation and an unmet need in bladder cancer. Exploitation of androgen receptor (AR) is a potential strategy for targeted drug development in bladder cancer. A significant proportion of urothelial carcinoma patients express AR irrespective of gender. AR signaling in urothelial carcinoma has been linked to progression through multiple mechanisms, including activation of human epidermal growth factor receptor-2 (EGFR or HER-2) signaling and epithelial to mesenchymal transition (EMT). Furthermore, AR is enriched in the luminal papillary mRNA subtype of urothelial carcinoma and also mediates resistance to cisplatin-based chemotherapy. Preclinical evidence suggests that AR inhibition can successfully inhibit urothelial carcinoma growth as monotherapy and is synergistic with cisplatin-based chemotherapy. We review the preclinical and clinical evidence supporting the putative role of AR signaling in urothelial carcinoma pathogenesis, progression and its role as a novel therapeutic target and future directions.

Impact of Testosterone Deficiency and Testosterone Therapy on Lower Urinary Tract Symptoms in Men with Metabolic Syndrome

Lower urinary tract function is modulated by neural, vascular and urethral and bladder structural elements. The pathophysiological mechanisms of lower urinary tract symptoms (LUTS) encompass prostate enlargement, alterations in urethra histological structure bladder fibrosis and alterations in pelvic neuronal and vascular networks, The complex pathophysiological relationship between testosterone (T) deficiency (TD) and the constellations LUTS, and metabolic dysfunction manifested in the metabolic syndrome (Met S) remains poorly understood. TD has emerged as one the potential targets by which Met S may contribute to the onset and development as well as worsening of LUTS. Because it has been recognized that treatment of men with Met S with T therapy ameliorates Met S components, it is postulated that T therapy may represent a therapeutic target in improving LUTS. Furthermore, the effect of TD on the prostate remains unclear, and often debatable. It is believed that T exclusively promotes prostate growth, however recent evidence has strongly contradicted this belief. The true relationship between benign prostatic hyperplasia, TD, and LUTS remains elusive and further research will be required to clarify the role of T in both benign prostatic hypertrophy (BPH) and LUTS as a whole. Although there is conflicting evidence about the benefits of T therapy in men with BPH and LUTS, the current body of literature supports the safety of using this therapy in men with enlarged prostate. As the population afflicted with obesity epidemic continues to age, the number of men suffering from Met S and LUTS together is expected to increase.

Role of the androgen receptor in urothelial cancer

Men have had a substantially higher risk of developing bladder cancer than women. This has prompted research on androgen-mediated androgen receptor (AR) signaling in urothelial cancer. Indeed, increasing preclinical evidence indicates that AR activation correlates with the promotion of urothelial carcinogenesis and tumor outgrowth. In this article, we summarize and discuss available data suggesting the involvement of androgens and the AR pathway in the development and progression of urothelial cancer. Although precise mechanisms for the functions of AR and related signals in urothelial cells remain far from being fully understood, current observations may offer effective chemopreventive and therapeutic approaches for urothelial cancer. Clinical application of various anti-AR therapies available for AR-dependent prostate cancer to urothelial cancer patients is thus anticipated.

Androgen Receptor Signaling in Bladder Cancer

Emerging preclinical findings have indicated that steroid hormone receptor signaling plays an important role in bladder cancer outgrowth. In particular, androgen-mediated androgen receptor signals have been shown to correlate with the promotion of tumor development and progression, which may clearly explain some sex-specific differences in bladder cancer. This review summarizes and discusses the available data, suggesting the involvement of androgens and/or the androgen receptor pathways in urothelial carcinogenesis as well as tumor growth. While the precise mechanisms of the functions of the androgen receptor in urothelial cells remain far from being fully understood, current evidence may offer chemopreventive or therapeutic options, using androgen deprivation therapy, in patients with bladder cancer.

Effect of testosterone therapy on the urinary bladder in experimental hypogonadism of rats

Testosterone (T) deficiency is prevalent particularly in elderly men and lead to physical and sexual morbidities. Although low levels of T are associated with low urinary tract symptoms, the correlation between T deficiency and bladder dysfunction is not clearly identified. The aim of this study was to investigate the effect of high dose testosterone replacement therapy (TRT) on the histological structure of the UB in castrated rats. Twenty-five adult male rats were divided into three groups: control, castrated and castrated + TRT. T was administrated in high dose (100 mg/kg) two intramuscular injections/week for 60 days. UB sections were prepared and stained with H&E, Masson's trichrome and immunohistochemical detection of Cytokeratin 20 (Ck20). All data were morphometrically and statistically analyzed. In castrated group, significant atrophy of the urothelium (P < 0.001) accompanied with widening of the corium were observed. The smooth muscle appeared thin with marked increase in the collagen fibers. On treating the castrated group with TRT, atypical Ck20 expression as well as significant increase in urothelial thickness (P < 0.05) and smooth muscle/collagen ratio (P < 0.001) were detected. In castrated rat model, high dose TRT has a positive effect on the UB smooth muscle rather than the urothelium which acquired atypical patterns.

Testosterone replacement therapy and prostate health

There is an emerging evolution in the understanding of the relationship between the prostate and testosterone. It has long been generally believed that with testosterone replacement therapy (TRT), increasing serum testosterone levels led to prostatic growth and worsening of voiding dysfunction and associated complications. A new theory, the Saturation Model of Testosterone and its effect on the Prostate has gained attention. This theory suggests that the prostate's response to increasing levels of serum testosterone reaches a limit beyond which there is minimal effect. This model predicts that testosterone replacement therapy occurs above this saturation point, and replacing testosterone to eugonadal levels should not worsen prostate related benign disease. We evaluated the recent published data, with an emphasis on clinical studies done within the last 3 years, for the effects of testosterone supplementation on benign prostatic disease.

The role of the androgen receptor in the development and progression of bladder cancer

Men are at a higher risk of developing bladder cancer than women. Since bladder cancer cell lines and tissues were found to express the androgen receptor, efforts have been made to inspect whether androgen-mediated androgen receptor signals are implicated in bladder carcinogenesis as well as cancer progression. Mounting evidence supports the view that bladder cancer is a member of the endocrine-related tumors and may clearly explain the gender-specific difference in the incidence. However, the underlying mechanisms of how androgen receptor signals regulate bladder cancer growth are still far from fully characterized. Moreover, it remains controversial whether the androgen receptor pathway always plays a dominant role in bladder cancer progression. In this review, we summarize the available data on the involvement of androgen receptor signaling in bladder cancer. In particular, current evidence demonstrating the stimulatory effects of androgens on tumor progression or, more convincingly, tumorigenesis via the androgen receptor pathway may offer great potential for androgen deprivation as a therapeutic or chemopreventive option in patients with bladder cancer.