The role of testosterone in the pathogenesis of prostate cancer

AR imposes different effects on ZFHX3 transcription depending on androgen status in prostate cancer cells

Both androgen receptor (AR) and the ZFHX3 transcription factor modulate prostate development. While AR drives prostatic carcinogenesis, ZFHX3 is a tumour suppressor whose loss activates the PI3K/AKT signalling in advanced prostate cancer (PCa). However, it is unknown whether ZFHX3 and AR are functionally related in PCa cells and, if so, how. Here, we report that in AR-positive LNCaP and C4-2B PCa cells, androgen upregulates ZFHX3 transcription via androgen-induced AR binding to the androgen-responsive elements (AREs) of the ZFHX3 promoter. Androgen also upregulated ZFHX3 transcription in vivo, as castration dramatically reduced Zfhx3 mRNA and protein levels in mouse prostates, and ZFHX3 mRNA levels correlated with AR activities in human PCa. Interestingly, the binding of AR to one ARE occurred in the absence of androgen, and the binding repressed ZFHX3 transcription as this repressive binding was interrupted by androgen treatment. The enzalutamide antiandrogen prevented androgen from inducing ZFHX3 transcription and caused excess ZFHX3 protein degradation. In human PCa, ZFHX3 was downregulated and the downregulation correlated with worse patient survival. These findings establish a regulatory relationship between AR and ZFHX3, suggest a role of ZFHX3 in AR function and implicate ZFHX3 loss in the antiandrogen therapies of PCa.

Differential but Concerted Expression of HSD17B2, HSD17B3, SHBG and SRD5A1 Testosterone Tetrad Modulate Therapy Response and Susceptibility to Disease Relapse in Patients with Prostate Cancer

Simple Summary

Over the last two decades, our improved understanding of the pathobiology of androgen-addicted prostate cancer (PCa), and documented therapeutic advances/breakthroughs have not translated into any substantial or sustained curative benefit for patients treated with traditional ADT or novel immune checkpoint blockade therapeutics. This is invariably connected with the peculiar biology and intratumoral heterogeneity of PCa. Castration-resistant PCa, constituting ~30% of all PCa, remains a clinically enigmatic and therapeutically challenging disease sub-type, that is therapy-refractory and characterized by high risk for recurrence after initial response. Our findings highlight the role and exploitability of testosterone metabolic reprogramming in prostate TME for patient stratification and personalized/precision medicine based on the differential but concerted expression of molecular components of the proposed testosterone tetrad in patients with therapy-refractory, locally advanced, or recurrent PCa. The therapeutic exploitability and clinical feasibility of our proposed approach is suggested by our preclinical findings.

Abstract

Background: Testosterone plays a critical role in prostate development and pathology. However, the impact of the molecular interplay between testosterone-associated genes on therapy response and susceptibility to disease relapse in PCa patients remains underexplored. Objective: This study investigated the role of dysregulated or aberrantly expressed testosterone-associated genes in the enhanced dissemination, phenoconversion, and therapy response of treatment-resistant advanced or recurrent PCa. Methods: Employing a combination of multi-omics big data analyses, in vitro, ex vivo, and in vivo assays, we assessed the probable roles of HSD17B2, HSD17B3, SHBG, and SRD5A1-mediated testosterone metabolism in the progression, therapy response, and prognosis of advanced or castration-resistant PCa (CRPC). Results: Our bioinformatics-aided gene expression profiling and immunohistochemical staining showed that the aberrant expression of the HSD17B2, HSD17B3, SHBG, and SRD5A1 testosterone metabolic tetrad characterize androgen-driven PCa and is associated with disease progression. Reanalysis of the TCGA PRAD cohort (n = 497) showed that patients with SRD5A1-dominant high expression of the tetrad exhibited worse mid-term to long-term (≥5 years) overall survival, with a profoundly shorter time to recurrence, compared to those with low expression. More so, we observed a strong association between enhanced HSD17B2/SRD5A1 signaling and metastasis to distant lymph nodes (M1a) and bones (M1b), while upregulated HSD17B3/SHBG signaling correlated more with negative metastasis (M0) status. Interestingly, increased SHBG/SRD5A1 ratio was associated with metastasis to distant organs (M1c), while elevated SRD5A1/SHBG ratio was associated with positive biochemical recurrence (BCR) status, and shorter time to BCR. Molecular enrichment and protein–protein connectivity network analyses showed that the androgenic tetrad regulates testosterone metabolism and cross-talks with modulators of drug response, effectors of cell cycle progression, proliferation or cell motility, and activators/mediators of cancer stemness. Moreover, of clinical relevance, SHBG ectopic expression (SHBG_OE) or SRD5A1 knockout (sgSRD5A1) induced the acquisition of spindle fibroblastoid morphology by the round/polygonal metastatic PC-3 and LNCaP cells, attenuated their migration and invasion capability, and significantly suppressed their ability to form primary or secondary tumorspheres, with concomitant downregulation of stemness KLF4, OCT3/4, and drug resistance ABCC1, ABCB1 proteins expression levels. We also showed that metronomic dutasteride synergistically enhanced the anticancer effect of low-dose docetaxel, in vitro, and in vivo. Conclusion: These data provide proof of concept that re-reprogramming of testosterone metabolism through “SRD5A1 withdrawal” or “SHBG induction” is a workable therapeutic strategy for shutting down androgen-driven oncogenic signals, reversing treatment resistance, and repressing the metastatic/recurrent phenotypes of patients with PCa.

The use of zebrafish model in prostate cancer therapeutic development and discovery

Zebrafish is now among the leading in vivo model for cancer research, including prostate cancer. They are an alternative economic model being used to study cancer development, proliferation, and metastasis. They can also be effectively utilized for the development of cancer drugs at all levels, including target validation, and high-throughput screening for possible lead molecules. In this review, we provide a comprehensive overview of the role of zebrafish as an in vivo model in prostate cancer research. Globally, prostate cancer is a leading cause of death in men. Although many molecular mechanisms have been identified as playing a role in the pathogenesis of prostate cancer, there is still a significant need to understand the initial events of the disease. Furthermore, current treatments are limited by the emergence of severe toxicities and multidrug resistance. There is an essential need for economical and relevant research tools to improve our understanding and overcome these problems. This review provides a comprehensive summary of studies that utilized zebrafish for different aims in prostate cancer research. We discuss the use of zebrafish in prostate cancer cell proliferation and metastasis, defining signaling pathways, drug discovery and therapeutic development against prostate cancer, and toxicity studies. Finally, this review highlights limitations in this field and future directions to efficiently use zebrafish as a robust model for prostate cancer therapeutics development.

Molecular MR Imaging of Prostate Cancer

This review summarizes recent developments regarding molecular imaging markers for magnetic resonance imaging (MRI) of prostate cancer (PCa). Currently, the clinical standard includes MR imaging using unspecific gadolinium-based contrast agents. Specific molecular probes for the diagnosis of PCa could improve the molecular characterization of the tumor in a non-invasive examination. Furthermore, molecular probes could enable targeted therapies to suppress tumor growth or reduce the tumor size.

Urological second malignant neoplasms in testicular nonseminoma survivors: a population-based analysis

PURPOSE

Patients with testicular non-seminomatous germ cell tumors in the modern cisplatin-based chemotherapy era show favorable outcomes, yielding survivors exposed to increased risk of second malignant neoplasms. The carcinogenic effects of cisplatin were well established, and its side effects had shown close connections with the urinary system. The study aimed to evaluate how the characteristics of the primary testicular nonseminoma are associated with urological second malignant neoplasms and survival outcomes.

METHODS

Using the Surveillance, Epidemiology and End Results database, standardized incidence ratios (SIR) for three major urological tumors including kidney, bladder, and prostate cancer were calculated for 10,734 patients with testicular nonseminoma from 1975 to 2016. The survival analyses were performed using the Kaplan-Meier method and log-rank test, risk factors for overall survival were determined by Cox regression.

RESULTS

We identified a total of 197 patients with secondary urological neoplasms. Patients with previous testicular nonseminoma had elevated risk of kidney cancer (SIR 2.13, 95% CI 1.59-2.79), bladder cancer (SIR 1.47, 95% CI 1.07-1.59), and decreased risks of prostate cancer (SIR 0.75, 95% CI 0.61-0.91) compared with the general population. Patients diagnosed with testicular nonseminoma had favorable prognosis with 10-year overall survival reaching 91.8%, and patients with urological second malignant neoplasms showed better prognoses than patients with other second malignant neoplasms (log-rank P < 0.001).

CONCLUSION

Testicular nonseminoma survivors showed higher risks of kidney and bladder cancer associated with chemotherapy and decreased risk of prostate cancer. The prognosis of urological second neoplasms was better than other tumor origins.

COVID-19 and androgen-targeted therapy for prostate cancer patients

The current pandemic (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a global health challenge with active development of antiviral drugs and vaccines seeking to reduce its significant disease burden. Early reports have confirmed that transmembrane serine protease 2 (TMPRSS2) and angiotensin converting enzyme 2 (ACE2) are critical targets of SARS-CoV-2 that facilitate viral entry into host cells. TMPRSS2 and ACE2 are expressed in multiple human tissues beyond the lung including the testes where predisposition to SARS-CoV-2 infection may exist. TMPRSS2 is an androgen-responsive gene and its fusion represents one of the most frequent alterations in prostate cancer. Androgen suppression by androgen deprivation therapy and androgen receptor signaling inhibitors form the foundation of prostate cancer treatment. In this review, we highlight the growing evidence in support of androgen regulation of TMPRSS2 and ACE2 and the potential clinical implications of using androgen suppression to downregulate TMPRSS2 to target SARS-CoV-2. We also discuss the future directions and controversies that need to be addressed in order to establish the viability of targeting TMPRSS2 and/or ACE2 through androgen signaling regulation for COVID-19 treatment, particularly its relevance in the context of prostate cancer management.

Differentially Expressed Genes Associated With Prognosis in Locally Advanced Lymph Node-Negative Prostate Cancer

Older age is one of the main risk factors for cancer development. The incidence of prostate cancer, as a multifactorial disease, also depends upon demographic factors, race, and genetic predisposition. Prostate cancer most frequently occurs in men over 60 years of age, indicating a clear association between older age and disease onset. Carcinogenesis is followed by the deregulation of many genes, and some of these changes could serve as biomarkers for diagnosis, prognosis, prediction of drug therapy efficacy, as well as possible therapeutic targets. We have performed a bioinformatic analysis of a The Cancer Genome Atlas (TCGA) data and RNA-Seq profiling of a Russian patient cohort to reveal prognostic markers of locally advanced lymph node-negative prostate cancer (lymph node-negative LAPC). We also aimed to identify markers of the most common molecular subtype of prostate cancer carrying a fusion transcript TMPRSS2-ERG. We have found several genes that were differently expressed between the favorable and unfavorable prognosis groups and involved in the enriched KEGG pathways based on the TCGA (B4GALNT4, PTK6, and CHAT) and Russian patient cohort data (AKR1C1 and AKR1C3). Additionally, we revealed such genes for the TMPRSS2-ERG prostate cancer molecular subtype (B4GALNT4, ASRGL1, MYBPC1, RGS11, SLC6A14, GALNT13, and ST6GALNAC1). Obtained results contribute to a better understanding of the molecular mechanisms behind prostate cancer progression and could be used for further development of the LAPC prognosis marker panel.

Profiling Prostate Cancer Therapeutic Resistance

The major challenge in the treatment of patients with advanced lethal prostate cancer is therapeutic resistance to androgen-deprivation therapy (ADT) and chemotherapy. Overriding this resistance requires understanding of the driving mechanisms of the tumor microenvironment, not just the androgen receptor (AR)-signaling cascade, that facilitate therapeutic resistance in order to identify new drug targets. The tumor microenvironment enables key signaling pathways promoting cancer cell survival and invasion via resistance to anoikis. In particular, the process of epithelial-mesenchymal-transition (EMT), directed by transforming growth factor-β (TGF-β), confers stem cell properties and acquisition of a migratory and invasive phenotype via resistance to anoikis. Our lead agent DZ-50 may have a potentially high efficacy in advanced metastatic castration resistant prostate cancer (mCRPC) by eliciting an anoikis-driven therapeutic response. The plasticity of differentiated prostate tumor gland epithelium allows cells to de-differentiate into mesenchymal cells via EMT and re-differentiate via reversal to mesenchymal epithelial transition (MET) during tumor progression. A characteristic feature of EMT landscape is loss of E-cadherin, causing adherens junction breakdown, which circumvents anoikis, promoting metastasis and chemoresistance. The targetable interactions between androgens/AR and TGF-β signaling are being pursued towards optimized therapeutic regimens for the treatment of mCRPC. In this review, we discuss the recent evidence on targeting the EMT-MET dynamic interconversions to overcome therapeutic resistance in patients with recurrent therapeutically resistant prostate cancer. Exploitation of the phenotypic landscape and metabolic changes that characterize the prostate tumor microenvironment in advanced prostate cancer and consequential impact in conferring treatment resistance are also considered in the context of biomarker discovery.

Impact of visceral fat volume and fat density on biochemical outcome after radical prostatectomy and postoperative radiotherapy

BACKGROUND

To assess the predictive value of visceral adipose tissue (VAT) and adipose tissue density after both radical prostatectomy (RP) and adjuvant or salvage external beam radiotherapy (EBRT).

MATERIALS AND METHODS

We randomly selected 201 patients treated with RP and EBRT between 2005 and 2015. Visceral adipose tissue and subcutaneous adipose tissue volumes were manually contoured and corresponding tissue densities in Hounsfield units (HU) calculated. Time to biochemical recurrence (BCR) was calculated using the Kaplan-Meier method and comparisons were made using the log-rank test. Cox regression analysis was done for multivariate analysis.

RESULTS

Median time to BCR or last follow-up was 32 months. In univariate analysis for BCR, VAT volume and fat density were both associated with a better outcome (p=0.025 and p=0.024, respectively) as well as seminal vesicle involvement (p=0.024). Body mass index (BMI) was not predictive of BCR (p=0.32). In a multivariate model including seminal vesicle involvement, both a VAT volume above the median (HR2.5, 95%CI 1.1-5.7, p=0.03) and a VAT density (HR 2.4, 95%CI 1.1-5.1, p=0.028) above the median remained predictive for a better biochemical outcome. Adjusting for BMI did not significantly change the model.

CONCLUSIONS

In both univariate and multivariate analysis, patients with both a larger VAT volume and density had a better biochemical outcome. The interaction between prostate cancer aggressiveness and visceral fat volume and density needs to be further evaluated to provide a better understanding of this disease.

Low serum dehydroepiandrosterone examined by liquid chromatography-tandem mass spectrometry correlates with poor prognosis in hormone-naïve prostate cancer

BACKGROUND

There is no consensus on blood adrenal androgen concentrations in men with different stages and pathological grades of prostate cancer. In this study, dehydroepiandrosterone (DHEA) concentrations in blood were examined by ultrasensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS). We analyzed the correlation between DHEA concentrations in blood and clinicopathological findings of prostate cancer.

METHODS

We analyzed 196 men (mean age 70 years) with prostate cancer. The patients underwent systematic needle biopsy, and peripheral blood sampling was conducted for measurement of DHEA. DHEA concentrations in blood were determined using LC-MS/MS method. Patient age, serum prostate-specific antigen, prostate volume measured by ultrasound, and DHEA levels in blood were compared with Gleason score and clinical stage by multivariate analyses.

RESULTS

Median value of PSA and prostate volume were 11.5 ng/ml and 27.7 ml, respectively. Median concentration of DHEA in blood was 1,506.4 pg/ml. There was no correlation between serum DHEA and clinical variables such as age, serum PSA, and prostate volume. In multivariate analysis, low serum DHEA levels in prostate cancer patients were significantly related to high Gleason score and advanced clinical stage. Serum PSA levels in prostate cancer patients were also significantly associated with high Gleason score and advanced clinical stage. High serum PSA and low serum DHEA levels were significantly associated with poor prognosis factors in men with hormone-naïve prostate cancer.

CONCLUSIONS

DHEA concentrations in blood were examined by newly developed ultrasensitive LC-MS/MS. We confirmed that low serum DHEA levels in prostate cancer patients were related to high Gleason score and advanced clinical stage. These results suggest that serum DHEA level may be a useful prognostic factor in prostate cancer patients.

Preoperative low serum testosterone is associated with high-grade prostate cancer and an increased Gleason score upgrading

BACKGROUND

To compare histological feature of prostate cancer (PCa) according androgenic status in patients who underwent radical prostatectomy (RP).

METHODS

Between March 2007 and September 2013, we prospectively analysed 937 patients who were referred to our centre for RP. Clinical, pathological and biological data have been prospectively collected. Preoperative total testosterone (TT) and bioavailable testosterone (BT) serum determinations were carried out. The threshold for low serum testosterone was set at TT<3 ng/ml. Preoperative PSA value was registered. Gleason score (GS) and predominant Gleason pattern were determined in prostate biopsies and in prostate tissue specimens, crosschecked by two uro-pathologists.

RESULTS

Nine hundred and thirty-seven consecutive patients were included. In all, 14.9% patients had low TT in the population. An exact match between biopsy and prostate specimens in GS grading was observed for 50.6% patients (n=474). Also, 40.9% of all patients were upgraded (n=383): 45.3% (n=63) in low serum testosterone patients and 40.1% (n=320) in normal serum testosterone patients. For prostate specimens, the proportion of patients with predominant Gleason pattern 4 was higher in patients with low TT compared with normal TT (41.7% vs 29.1%, P=0.0029). In all, 20.1% were upgraded from predominant Gleason pattern 3 on biopsies specimen to predominant Gleason 4 pattern on the prostate specimen in patients with low TT, whereas 11.6% were upgraded for normal TT patients (P=0.002).

CONCLUSIONS

Low serum testosterone is an independent risk factor for predominant Gleason pattern 4 on prostate specimen after RP and for upgrading from low- to high-grade cancer between prostate needle biopsies and RP specimen. This observation should be taken into account in localised PCa management, especially for active surveillance or when a nerve-sparing approach is considered.

Identifying New Candidate Genes and Chemicals Related to Prostate Cancer Using a Hybrid Network and Shortest Path Approach

Prostate cancer is a type of cancer that occurs in the male prostate, a gland in the male reproductive system. Because prostate cancer cells may spread to other parts of the body and can influence human reproduction, understanding the mechanisms underlying this disease is critical for designing effective treatments. The identification of as many genes and chemicals related to prostate cancer as possible will enhance our understanding of this disease. In this study, we proposed a computational method to identify new candidate genes and chemicals based on currently known genes and chemicals related to prostate cancer by applying a shortest path approach in a hybrid network. The hybrid network was constructed according to information concerning chemical-chemical interactions, chemical-protein interactions, and protein-protein interactions. Many of the obtained genes and chemicals are associated with prostate cancer.

Preoperative Serum Sex Hormone-Binding Globulin Level Is an Independent Predictor of Biochemical Outcome After Radical Prostatectomy

To investigate the significance of preoperative serum sex hormone-binding globulin (SHBG) level regarding the postoperative biochemical outcome in patients who were followed up for relative longer periods after undergoing radical prostatectomy (RP). Preoperative serum levels of testosterone (T), free T, and SHBG level were prospectively analyzed in 307 consecutive patients who underwent RP at our institution between January 2006 and July 2007. We analyzed potential associations of sex hormones with postoperative biochemical recurrence (BCR)-free survival via multivariate Cox proportional regression analysis. Mean postoperative follow-up duration for 307 total patients was 72.1 ± 19.6 months. Kaplan-Meier curve demonstrated that BCR-free survival was significantly worse in patients with higher (≥ 40  ng/mL) SHBG level than others (P < 0.001). Serum T (P = 0.280) and free T (P = 0.606) levels showed no significant association with biochemical outcome. In multivariate analysis encompassing postoperative variables along with PSA, T, and free T, SHBG level (HR 1.825, 1.061-3.138; P = 0.030) was observed to be independently associated with BCR-free survival. Addition of SHBG level to the multivariate model for prediction of BCR-free survival resulted in increased accuracy (83.5% vs. 82.2%; P = 0.164). Our study of patients who were followed up for relative longer periods after RP shows that preoperative serum SHBG level, but not T, is an independent predictor of postoperative BCR-free survival. According to our findings, SHBG measurement may be useful in the selection of candidates for adjuvant treatment following RP.

Racial Differences in Age-Related Variations of Testosterone Levels Among US Males: Potential Implications for Prostate Cancer and Personalized Medication

AIM

The magnitude of the age-related declines in testosterone rather than levels measured at single point in time may be related to the genesis of prostate cancer (PCa). We examined age-related variations of testosterone levels among black and white males, which may provide important insights into racial disparities in PCa incidence and mortality.

METHOD

We analyzed data from the 1999-2004 National Health and Nutritional Examination Survey to compare age-related variations in the testosterone levels of 355 black and 631 white males.

RESULT

Overall, between the ages of 12 and 15, black males had lower testosterone levels than white males. Testosterone levels increased rapidly with age and reached higher and earlier peak levels in black males compared to white males at 20-30 years of age. After reaching a peak level, testosterone levels declined earlier in blacks than in whites. Further analyses showed that black males had considerably higher levels of testosterone compared to white males aged 20-39 years after adjusting for covariates, including age, body mass index, cigarette smoking, physical activity, and waist circumference; however, no statistically significant differences were observed between the groups at any other age.

CONCLUSION

Our study revealed that testosterone levels in black males decrease substantially with increasing age compared to those in white males. This rapid drop in testosterone levels may contribute to racial disparities in PCa. Our findings also suggest that personalized medication for hormone replacement therapy may be necessary to avoid sudden drops in testosterone levels, particularly for black males.

Intratumoral steroidogenesis in castration-resistant prostate cancer: a target for therapy

Development of castration-resistant prostate cancer (CRPC) in a low androgen environment, arising from androgen deprivation therapy (ADT), is a major problem in patients with advanced prostate cancer (PCa). Several mechanisms have been hypothesized to explain the progression of PCa to CRPC during ADT, one of them is so called persistent intratumoral steroidogenesis. The existence of intratumoral steroidogenesis was hinted based on the residual levels of intraprostatic testosterone (T) and dihydrotestosterone (DHT) after ADT. Accumulating evidence has shown that the intraprostatic androgen levels after ADT are sufficient to induce cancer progression. Several studies now have demonstrated that PCa cells are able to produce T and DHT from different androgen precursors, such as cholesterol and the adrenal androgen, dehydroepiandrosterone (DHEA). Furthermore, up-regulation of genes encoding key steroidogenic enzymes in PCa cells seems to be an indicator for active intratumoral steroidogenesis in CRPC cells. Currently, several drugs are being developed targeting those steroidogenic enzymes, some of which are now in clinical trials or are being used as standard care for CRPC patients. In the future, novel agents that target steroidogenesis may add to the arsenal of drugs for CRPC therapy.

DNA damage response and prostate cancer: defects, regulation and therapeutic implications

DNA damage response (DDR) includes the activation of numerous cellular activities that prevent duplication of DNA lesions and maintain genomic integrity, which is critical for the survival of normal and cancer cells. Specific genes involved in the DDR such as BRCA1/2 and P53 are mutated during prostate cancer progression, while various oncogenic signaling such as Akt and c-Myc are activated, enhancing the replication stress and increasing the genomic instability of cancer cells. These events may render prostate cancer cells particularly sensitive to inhibition of specific DDR pathways, such as PARP in homologous recombination (HR) DNA repair and Chk1 in cell cycle checkpoint and DNA repair, creating opportunities for synthetic lethality or synergistic cytotoxicity. Recent reports highlight the critical role of androgen receptor (AR) as a regulator of DDR genes, providing a rationale for combining DNA-damaging agents or targeted DDR inhibitors with hormonal manipulation or AR inhibition as treatment for aggressive disease. The aims of this review are to discuss specific DDR defects in prostate cancer that occur during disease progression, to summarize recent advances in understanding the regulation of DDR in prostate cancer, and to present potential therapeutic opportunities through combinational targeting of the intact components of DDR signaling pathways.

CYP17 inhibitors--abiraterone, C17,20-lyase inhibitors and multi-targeting agents

As the first in class steroid 17α-hydroxylase/C17,20-lyase (CYP17) inhibitor, abiraterone acetate (of which the active metabolite is abiraterone) has been shown to improve overall survival in patients with castration-resistant prostate cancer (CRPC)--in those who are chemotherapy-naive and those previously treated with docetaxel. Furthermore, the clinical success of abiraterone demonstrated that CRPC, which has previously been regarded as an androgen-independent disease, is still driven, at least in part, by androgens. More importantly, abiraterone is a 'promiscuous' drug that interacts with a number of targets, which dictate its clinical benefits and adverse effects profile. Besides CYP17 inhibition, abiraterone acts as an antagonist to the androgen receptor and inhibits 3β-hydroxysteroid dehydrogenase--two effects that potentially contribute to its antitumour effects. However, the inhibition of the 17α-hydroxylase activity of CYP17, CYP11B1 and a panel of hepatic CYP enzymes leads to adverse effects and toxicities that include secondary mineralocorticoid excess. Abiraterone is also associated with increased incidence of cardiac disorders. Under such circumstances, development of new CYP17 inhibitors as an additional line of defence is urgently needed. To achieve enhanced clinical benefits, new strategies are being explored that include selective inhibition of the C17,20-lyase activity of CYP17 and multi-targeting strategies that affect androgen synthesis and signalling at different points. Some of these strategies-including the drugs orteronel, VT-464 and galeterone--are supported by preclinical data and are being explored in the clinic.

The hypothalamic-pituitary-gonadal axis and prostate cancer: implications for androgen deprivation therapy

Luteinizing hormone (LH) and follicle-stimulating hormone (FSH) may play important roles in prostate cancer (PCa) progression. Specifically, LH expression in PCa tissues has been associated with metastatic disease with a poor prognosis, while FSH has been shown to stimulate prostate cell growth in hormone-refractory PCa cell lines. Gonadotropin-realizing hormone (GnRH) analogues are common agents used for achieving androgen deprivation in the treatment for PCa. GnRH analogues include LH-releasing hormone (LHRH) agonists and GnRH antagonists, both of which exhibit distinct mechanisms of action that may be crucial in terms of their overall clinical efficacy. LHRH agonists are typically used as the primary therapy for most patients and function via a negative-feedback mechanism. This mechanism involves an initial surge in testosterone levels, which may worsen clinical symptoms of PCa. GnRH antagonists provide rapid and consistent hormonal suppression without the initial surge in testosterone levels associated with LHRH agonists, thus representing an important therapeutic alternative for patients with PCa. The concentrations of testosterone and dihydrotestosterone are significantly reduced after treatment with both LHRH agonists and GnRH antagonists. This reduction in testosterone concentrations to castrate levels results in significant, rapid, and consistent reductions in prostatic-specific antigen, a key biomarker for PCa. Evidence suggests that careful maintenance of testosterone levels during androgen deprivation therapy provides a clinical benefit to patients with PCa, emphasizing the need for constant monitoring of testosterone concentrations throughout the course of therapy.

Prediagnostic circulating sex hormones are not associated with mortality for men with prostate cancer

BACKGROUND

Sex hormones play an important role in the growth and development of the prostate, and low androgen levels have been suggested to carry an adverse prognosis for men with prostate cancer (PCa).

OBJECTIVE

To examine the association between prediagnostic circulating sex hormones and lethal PCa in two prospective cohort studies, the Physicians' Health Study (PHS) and the Health Professionals Follow-up Study (HPFS).

DESIGN, SETTING, AND PARTICIPANTS

We included 963 PCa cases (700 HPFS; 263 PHS) that provided prediagnostic blood samples, in 1982 for PHS and in 1993-1995 for HPFS, in which circulating sex hormone levels were assayed.

OUTCOME MEASURES AND STATISTICAL ANALYSIS

The primary end point was lethal PCa (defined as cancer-specific mortality or development of metastases), and we also assessed total mortality through March 2011. We used Cox proportional hazards models to evaluate the association of prediagnostic sex hormone levels with time from diagnosis to development of lethal PCa or total mortality.

RESULTS AND LIMITATIONS

PCa cases were followed for a mean of 12.0±4.9 yr after diagnosis. We confirmed 148 cases of lethal PCa and 421 deaths overall. Using Cox proportional hazard models, we found no significant association between quartile of total testosterone, sex hormone binding globulin (SHBG), SHBG-adjusted testosterone, free testosterone, dihydrotestosterone, androstanediol glucuronide, or estradiol and lethal PCa or total mortality. In subset analyses stratified by Gleason score, TNM stage, age, and interval between blood draw and diagnosis, there was also no consistent association between lethal PCa and sex hormone quartile.

CONCLUSIONS

We found no overall association between prediagnostic circulating sex hormones and lethal PCa or total mortality. Our null results suggest that reverse causation may be responsible in prior studies that noted adverse outcomes for men with low circulating androgens.

Circulating sex steroids and prostate cancer: introducing the time-dependency theory

PURPOSE

We sought whether serum total testosterone (tT), estradiol (E2), tT/E2 ratio, and sex hormone-binding globulin (SHBG) significantly fluctuate throughout time in men with prostate cancer (PCa).

METHODS

Circulating hormones were measured in a cohort of 631 candidates for radical prostatectomy. Hormone levels were analyzed according to either patient age, stratified into quartiles, or body mass index (BMI). Linear regression analyses tested the association between sex steroids and continuously coded patient age and BMI values.

RESULTS

No significant differences were found among age quartiles regarding serum tT levels and tT/E2 ratio. Conversely, E2 and SHBG levels significantly increased throughout time (all, p ≤ 0.001). Total T did not linearly change according to continuously coded patient age; in contrast, E2 and SHBG linearly increased (all, p ≤ 0.001), whereas tT/E2 decreased (p = 0.016) with aging. Rate of hypogonadism significantly increased with aging (p = 0.04). Total T, T/E2 ratio, and SHBG linearly decreased along with BMI increases (all p ≤ 0.02), whereas serum E2 did not significantly change. Rate of hypogonadism significantly increased with BMI increases (p < 0.001).

CONCLUSIONS

In contrast with longitudinal studies in the general male population, these data indirectly suggest that serum tT levels could be stable over time in PCa patients. This finding led to formulation of a "time-dependency theory", which postulates that the endocrine biology of prostate tissue is dependent on the exposure time at a given concentration of sex steroid, which, in turn, fluctuates throughout the lifespan of the individual.

The cardiovascular risk of gonadotropin releasing hormone agonists in men with prostate cancer: an unresolved controversy

Gonadotropin-releasing hormone agonists (GnRH) play an important role in the treatment of prostate cancer, improving significantly overall survival. GnRH agonists belong to androgen deprivation therapy (ADT) together with surgical castration and, recently, GnRH antagonists. ADT has several side effects, such as sexual dysfunction and osteoporosis. Recently, changes in body composition, obesity, insulin resistance, hyperglycemia, dyslipidemia, and hypertension have emerged as complications of ADT, perhaps responsible for cardiovascular events, but discussion is still open. Since the majority of men with prostate cancer die of conditions other than their malignancy, recognition of these adverse effects is important. This review serves to focus attention on the pathogenetic mechanisms of ADT-related cardiovascular toxicity with also reference to the possible direct role of GnRH agonist on the cardiac receptors. Furthermore, this paper would generate recommendations for the management of patients treated with GnRH agonists balancing the potential benefits against the possible risks in prostate cancer men.

The effect of baseline testosterone on the efficacy of degarelix and leuprolide: further insights from a 12-month, comparative, phase III study in prostate cancer patients

OBJECTIVE

To investigate the effects of baseline testosterone on testosterone control and prostate-specific antigen (PSA) suppression using data from a phase III trial (CS21) comparing degarelix and leuprolide in prostate cancer.

METHODS

In CS21, patients with histologically confirmed prostate cancer (all stages) were randomized to degarelix 240 mg for 1 month followed by monthly maintenance doses of 80 or 160 mg, or leuprolide 7.5 mg/month. Patients receiving leuprolide could receive antiandrogens for flare protection. Treatment effects on testosterone and PSA reduction, testosterone surge, and microsurges were investigated in 3 baseline testosterone subgroups: <3.5, 3.5-5.0, and >5.0 ng/mL. Data are presented for the groups receiving degarelix 240/80 mg (the approved dose) and leuprolide 7.5 mg.

RESULTS

Higher baseline testosterone delayed castration with both treatments. However, castrate testosterone levels and PSA suppression occurred more rapidly with degarelix irrespective of baseline testosterone. With leuprolide, the magnitude of testosterone surge and microsurges increased with increasing baseline testosterone. There was no overall correlation between baseline testosterone and initial PSA decrease in either treatment group, although PSA suppression tended to be slowest with leuprolide and fastest with degarelix in the high baseline testosterone subgroup.

CONCLUSION

Patients with high baseline testosterone may have greater risk of tumor stimulation (clinical flare) and mini-flares during gonadotrophin-releasing hormone agonist treatment and so the need for flare protection with antiandrogens in these patients is obvious, especially in metastatic disease. Although higher baseline testosterone delays castration, castrate testosterone and PSA suppression occur more rapidly with degarelix, irrespective of baseline testosterone, without the need for flare protection.

Testosterone promotes DNA damage response under oxidative stress in prostate cancer cell lines

BACKGROUND

Sustained chronic inflammation and oxidative stress in the prostate promote prostate carcinogenesis. The process of oncogenic transformation leads to enhanced DNA damage and activates the checkpoint network that functions as an inducible barrier against cancer progression. Here, we analyzed the effects of testosterone on the DNA damage response in prostate cancer cells to assess whether testosterone functions a barrier to cancer progression under the oxidative stress.

METHODS

We examined the effects of testosterone on components of the DNA damage response pathway, including ATM (ataxia-telangiectasia-mutated kinase), H2AX (histone H2AX variant), and Chk2 (checkpoint kinase2) in prostate cancer cell lines, treated with various concentration of hydrogen peroxide (H(2) O(2) ). Cellular apoptosis was quantified by poly (ADP-ribose) polymerase (PARP) cleavage and flow cytometry.

RESULTS

H(2) O(2) induced apoptosis and phosphorylation of ATM, Chk2, and H2AX in LNCaP cells. An ATM inhibitor, Ku55933, reduced H(2) O(2) -induced apoptosis in LNCaP and 22Rv1 cells. Androgen treatments increased H(2) O(2) -induced activation of the DNA damage response and PARP cleavage, but not when the H(2) O(2) -treated cells were also treated with the anti-androgen flutamide. The ATM inhibitor Ku55933 inhibited androgen-induced phosphorylation of ATM and PARP cleavage.

CONCLUSIONS

DNA damage responses play important roles in the maintenance of the cell homeostasis in response to oxidative stress. Our results indicated that under oxidative stress androgen signaling may induce apoptosis by activating the DNA damage response.

Red wine and component flavonoids inhibit UGT2B17 in vitro

Background

The metabolism and excretion of the anabolic steroid testosterone occurs by glucuronidation to the conjugate testosterone glucuronide which is then excreted in urine. Alterations in UGT glucuronidation enzyme activity could alter the rate of testosterone excretion and thus its bioavailability. The aim of this study is to investigate if red wine, a common dietary substance, has an inhibitory effect on UGT2B17.

Methods

Testosterone glucuronidation was assayed using human UGT2B17 supersomes with quantification of unglucuronidated testosterone over time using HPLC with DAD detection. The selected red wine was analyzed using HPLC; and the inhibitory effects of the wine and phenolic components were tested independently in a screening assay. Further analyses were conducted for the strongest inhibitors at physiologically relevant concentrations. Control experiments were conducted to determine the effects of the ethanol on UGT2B17.

Results

Over the concentration range of 2 to 8%, the red wine sample inhibited the glucuronidation of testosterone by up to 70% over 2 hours. The ethanol content had no significant effect. Three red wine phenolics, identified by HPLC analyses, also inhibited the enzyme by varying amounts in the order of quercetin (72%), caffeic acid (22%) and gallic acid (9%); using a ratio of phenolic:testosterone of 1:2.5. In contrast p-coumaric acid and chlorogenic acid had no effect on the UGT2B17. The most active phenolic was selected for a detailed study at physiologically relevant concentrations, and quercetin maintained inhibitory activity of 20% at 2 μM despite a ten-fold excess of testosterone.

Conclusion

This study reports that in an in vitro supersome-based assay, the key steroid-metabolizing enzyme UGT2B17 is inhibited by a number of phenolic dietary substances and therefore may reduce the rate of testosterone glucuronidation in vivo. These results highlight the potential interactions of a number of common dietary compounds on testosterone metabolism. Considering the variety of foodstuffs that contain flavonoids, it is feasible that diet can elevate levels of circulating testosterone through reduction in urinary excretion. These results warrant further investigation and extension to a human trial to delineate the health implications.

Genome-wide association study identifies a new locus JMJD1C at 10q21 that may influence serum androgen levels in men

Circulating androgen levels are often used as indicators of physiological or pathological conditions. More than half of the variance for circulating androgen levels is thought to be genetically influenced. A genome-wide association study (GWAS) has identified two loci, SHBG at 17p13 and FAM9B at Xp22, for serum testosterone (T) levels; however, these explain only a small fraction of inter-individual variability. To identify additional genetic determinants of androgen levels, a GWAS of baseline serum T and dihydrotestosterone (DHT) levels was conducted in 3225 men of European ancestry from the REduction by DUtasteride of Prostate Cancer Events (REDUCE) study. Cross-validation was used to confirm the observed associations between the drug (n = 1581) and placebo (n = 1644) groups of REDUCE. In addition to confirming the associations of two known loci with serum T levels (rs727428 in SHBG: P = 1.26 × 10(-12); rs5934505 in FAM9B: P = 1.61 × 10(-8)), we identified a new locus, JMJD1C at 10q21 that was associated with serum T levels at a genome-wide significance level (rs10822184: P = 1.12 × 10(-8)). We also observed that the SHBG locus was associated with serum DHT levels (rs727428: P = 1.47 × 10(-11)). Moreover, two additional variants in SHBG [rs72829446, in strong linkage equilibrium with the missense variant D356N (rs6259), and rs1799941] were also independently associated with circulating androgen levels in a statistical scale. These three loci (JMJD1C, SHBG and FAM9B) were estimated to account for ~5.3 and 4.1% of the variance of serum T and DHT levels. Our findings may provide new insights into the regulation of circulating androgens and potential targets for androgen-based therapy.

Development and External Validation of a Nomogram Predicting the Probability of Significant Gleason Sum Upgrading among Japanese Patients with Localized Prostate Cancer

Objective. The aim of this study is to develop a prognostic model capable of predicting the probability of significant upgrading among Japanese patients. Methods. The study cohort comprised 508 men treated with RP, with available prostate-specific antigen levels, biopsy, and RP Gleason sum values. Clinical and pathological data from 258 patients were obtained from another Japanese institution for validation. Results. Significant Gleason sum upgrading was recorded in 92 patients (18.1%) at RP. The accuracy of the nomogram predicting the probability of significant Gleason sum upgrading between biopsy and RP specimens was 88.9%. Overall AUC was 0.872 when applied to the validation data set. Nomogram predictions of significant upgrading were within 7.5% of an ideal nomogram. Conclusions. Nearly one-fifth of Japanese patients with prostate cancer will be significantly upgraded. Our nomogram seems to provide considerably accurate predictions regardless of minor variations in pathological assessment when applied to Japanese patient populations.

The role of 5-alpha reductase inhibitors in prostate pathophysiology: Is there an additional advantage to inhibition of type 1 isoenzyme?

Normal growth and function of the prostate are contingent on the reduction of testosterone to dihydrotestosterone (DHT) by 5-alpha reductase (5-AR) enzymes types 1 and 2. It has been theorized that an overabundance of DHT may be implicated in the pathogenesis of both benign prostatic hyperplasia (BPH) and prostate cancer. Inhibitors of 5-AR such as dutasteride and finasteride may therefore have an important role in the prevention and treatment of BPH and prostate cancer. Dutasteride provides greater suppression of DHT than finasteride, thereby underlying the hypothesis that inhibition of both type 1 and type 2 would provide correspondingly greater protection than inhibition of type 2 alone. We review the potential significance of the 5-AR inhibitors in reducing the risk of prostate cancer according to the basic biology of prostate disease.

Targeting 5α-reductase for prostate cancer prevention and treatment

Testosterone is the most abundant circulating androgen, and can be converted to dihydrotestosterone (DHT), a more potent androgen, by the 5α-reductase enzymes in target tissues. Current treatments for prostate cancer consist of reducing androgen levels by chemical or surgical castration or pure antiandrogen therapy that directly targets the androgen receptor (AR). Although these therapies reduce tumor burden and AR activity, the cancer inevitably recurs within 18-30 months. An approach targeting the androgen-AR axis at different levels could, therefore, improve the efficacy of prostate cancer therapy. Inhibition of 5α-reductase is one such approach; however, the two largest trials to investigate the use of the 5α-reductase inhibitors (5ARIs) finasteride and dutasteride in patients with prostate cancer have shown that, although the incidence of cancer was reduced by 5ARI treatment, those cancers that were detected were more aggressive than in patients treated with placebo. Thus, the best practice for using these drugs to prevent and treat prostate cancer remains unclear.

Role of bacteria in oncogenesis

Although scientific knowledge in viral oncology has exploded in the 20th century, the role of bacteria as mediators of oncogenesis has been less well elucidated. Understanding bacterial carcinogenesis has become increasingly important as a possible means of cancer prevention. This review summarizes clinical, epidemiological, and experimental evidence as well as possible mechanisms of bacterial induction of or protection from malignancy.

Male infertility and prostate cancer risk: a nested case-control study

The pathogenesis of prostate cancer is unclear, although experimental evidence implicates androgens as playing an important role. Infertile men frequently suffer from some degree of hypogonadism and may hence be hypothesized to be at lower risk of developing prostate cancer than fertile men. To test this hypothesis, we conducted a case-control study nested within "the Malmö Diet and Cancer Study" cohort in Sweden, inviting 661 prostate cancer cases and 661 age-matched controls to participate. Of the 975 (74%) respondents, we excluded 84 childless men with unknown fertility status. Thus, 891 men were included, providing 445 prostate cancer cases and 446 controls. Of these, 841 (94%) men were biological fathers and 50 (6%) men were infertile. Logistic regression showed that the infertile men were at significantly lower risk of being diagnosed with prostate cancer than the fertile men (odds ratio, 0.45; 95% confidence interval, 0.25-0.83). Conditional and unconditional multivariate models, adjusting for socioeconomic, anthropometric, and health-status-related factors, provided similar estimates. We conclude that enduring male infertility is associated with a reduced prostate cancer risk, thus corroborating the theory that normal testicular function, and hence most probably sufficient steroidogenesis, is an important contributing factor to the later development of this malignancy.

Plant-derived alternative treatments for the aging male: facts and myths

Soy- or red clover- derived products containing isoflavones have been amply studied in climacteric and postmenopausal women, and confusing contradicting results have been published. The beneficial effects on climacteric complaints, cholesterol and the development of osteoporosis are marginally at best and there are no uterine and mammary safety studies. In males, however, isoflavones may protect the prostate to make them less prone to develop cancer. Cell biological and animal experimental data support this notion. Clinical data about possible beneficial effects on cholesterol or in the bone are largely missing. Hence, soy or red clover products containing the mild estrogenic isoflavones with a slightly higher affinity to the estrogen receptor of the beta in comparison to the alpha subtype may prove to have some beneficial effects in males.

Androgen-Deprivation Therapy in Prostate Cancer: Clinical Evidence and Future Perspectives

Androgens are involved in the development and progression of prostate cancer even if the mechanism is not well-recognized. For this reason androgen-deprivation therapy remains a milestone for the treatment of patients with advanced and metastatic disease and, in the last years, in conjunction with radiotherapy and surgery in locally advanced tumors. Alternative options, such as intermittent deprivation suppression, seem to be promising in terms of clinical benefits and toxicity profile. However, current therapies present side effects, such as testosterone surge with consequent clinical flare-up, metabolic syndrome and hormone-resistance, which develops after a variable number of years. Novel therapies such as LH-RH antagonists and prolonged depot LH-RH analogues have been developed in order to avoid clinical flare-up and testosterone microsurges. Novel androgen synthesis inhibitors, such as abiraterone acetate and MDV3100, have been recently discovered and tested as promising hormonal second-line agents in patients with castration-resistant prostate cancer. Finally, long-term side effects from androgen deprivation, such as osteoporosis, sarcopenic obesity and cardiovascular morbidity should be carefully monitored and properly treated.

Preoperative low serum testosterone levels are associated with tumor aggressiveness in radical prostatectomy treated cancer patients

: The aim of this study was to characterize the aggressiveness of prostate cancer as assessed by the Gleason score (GS), the predominant Gleason pattern (pGP), and testosterone (T) serum concentration.

: A total of 247 patients, referred to our Department (from January 2007 to December 2009) for a radical prostatectomy, underwent preoperative T and bioavailable testosterone (samplings between 07:00 and 10:00 h). Serum determinations (radioimmunoassayed in a central laboratory). GS and pGP were determined in prostate biopsies and prostate tissue specimens.

: In biopsy specimens, a GS7 was observed in 105 (43%) patients; 25 (10%) had pGP4. In prostate specimens, 163 (66%) had a GS7; 60 (24%) had pGP4. For prostate specimens, comparing the 75 patients with pGP4 (GS 4+3, 4+4 and 4+5) to the 172 with pGP3 (GS 3+3 and 3+4), T was lower (4.03 vs. 4.75 ng/mL, p=0.003) and prostrate-specific antigen (PSA) higher (11.1 vs. 7.3 ng/mL, p<0.00001). Extra prostatic extension and positive margins were observed more frequently (52% vs. 18%, p<0.000001 and 29% vs. 15%, p=0.009, respectively). The 40 patients with T <3.0 ng/mL were larger (+5 kg, body mass index: +1.7 kg/m

: Aggressiveness of the tumor cannot be properly estimated by the GS and pGP found in biopsies. The pGP in prostate specimens is of paramount importance, particularly in the case of a Gleason 7, to appreciate the outcomes and to choose the treatment. Preoperative testosterone should be added to PSA determination to improve prediction of treatment outcomes.

External validation of a nomogram predicting the probability of prostate cancer Gleason sum upgrading between biopsy and radical prostatectomy pathology among Japanese patients

OBJECTIVES

To explore the rate of upgrading in a contemporary cohort from 2 Japanese institutions, and evaluating the predictive accuracy of the nomogram when applied to patients, regardless of race. Previous reports have indicated that a maximum of 43% of men with prostate cancer will show an upgraded Gleason score from biopsy to radical prostatectomy (RP). A preparative nomogram was developed at the University of Hamburg to predict the probability of upgrading from biopsy to RP specimen.

METHODS

Clinical and pathologic data of 503 patients from 2 Japanese institutions were supplied for validation. Nomogram-predicted probabilities of upgrading from biopsy to RP specimen were compared with actual rate of upgrading. The area under the receiver operating characteristic curve (AUC) was calculated for all patients. Calibration of the nomogram was achieved by comparing the predicted upgrading rate with that of an ideal nomogram.

RESULTS

Gleason sum upgrading was recorded in 29.8% of patients at RP. Accuracy of the nomogram was 79.2% (confidence interval, 75.1%-83.2%). Overall AUC was 0.79 when applied to the validation dataset, with individual institutional AUCs ranging from 0.79-0.80. Nomogram predictions of upgrading were not within 10% of an ideal nomogram.

CONCLUSIONS

Gleason sum upgrading between biopsy and final pathology represents an important consideration in treatment decision-making, and nearly one third of patients with prostate cancer will be upgraded. The Hamburg nomogram seems to provide reasonably accurate predictions regardless of minor variations in pathologic assessment, but is not necessarily so accurate when applied to Japanese patient population.

Can the Mediterranean diet prevent prostate cancer?

Prostate cancer is the second most common cancer in men worldwide. Despite the global importance of this cancer, until recently little was known about risk factors apart from the well-established factors: age, family history and country of birth. The large worldwide variation in prostate cancer risk and increased risk in migrants moving from low to high risk countries provides strong support for modifiable environmental factors. We have based our review on the findings of a systematic review undertaken by an expert panel on behalf of the World Cancer Research Fund and the American Institute for Cancer Research, and new data since then, linking identified foods and nutrients with prostate cancer. Evidence indicates that foods containing lycopene, as well as selenium and foods containing it, probably protect against prostate cancer, and excess consumption of foods or supplements containing calcium are a probable cause of this cancer. The expert panel also concluded that it is unlikely that beta-carotene (whether from foods or supplements) has a substantial effect on the risk of this cancer. A recent review on environmental factors in human prostate cancer also found that there were protective effects of vitamin E, pulses, soy foods and high plasma 1,25-dihydroxyvitamin D levels. The Mediterranean diet is abundant in foods that may protect against prostate cancer and is associated with longevity and reduced cardiovascular and cancer mortality. Compared with many Western countries Greece has lower prostate cancer mortality and Greek migrant men in Australia have retained their low risk for prostate cancer. Consumption of a traditional Mediterranean diet, rich in bioactive nutrients, may confer protection to Greek migrant men, and this dietary pattern offers a palatable alternative for prevention of this disease.

Androgen deprivation therapy: progress in understanding mechanisms of resistance and optimizing androgen depletion

Androgen deprivation therapy remains a critical component of treatment for men with advanced prostate cancer, and data support its use in metastatic disease and in conjunction with surgery or radiation in specific settings. Alternatives to standard androgen deprivation therapy, such as intermittent androgen suppression and estrogen therapy, hold the potential to improve toxicity profiles while maintaining clinical benefit. Current androgen deprivation strategies seem to incompletely suppress androgen levels and androgen-receptor-mediated effects at the tissue level. Advances in the understanding of mechanisms that contribute to castration-resistant prostate cancer are leading to rationally designed therapies targeting androgen metabolism and the androgen receptor. The results of large trials investigating the optimization of primary androgen deprivation therapy, including evaluation of intermittent androgen suppression and phase III studies of novel androgen synthesis inhibitors, such as abiraterone acetate, are eagerly awaited.

Implications of insulin-like growth factor-I for prostate cancer therapies

In the last decade, abundant evidence has suggested that the insulin-like growth factor (IGF) family comprises a multi-component network of molecules involved in the regulation of both physiological and pathological growth processes in the prostate. The IGF axis plays an important role in the tumorigenesis and neoplastic growth of prostate cancer. Epidemiological observations indicate that circulating IGF-I levels are positively associated with increased risk of prostate cancer. Activation of IGF-I receptor (IGF-IR) by IGF-I has mitogenic and anti-apoptotic effects on normal and malignant prostate cells. Therapeutic alternatives in men with progressive prostate cancer after androgen ablation are very limited and more effective therapies are needed for such patients. Inactivation of the IGF-I axis represents a potential target to treat androgen-independent prostate cancer. This review addresses epidemiological studies of IGF-I and therapeutic strategies including reduction of IGF-I levels, inhibition of IGF-IR and the signaling mechanisms involved.

Current topics and perspectives relating to hormone therapy for prostate cancer

Prostate cancer is androgen-dependent, and hormone therapy, mainly achieved by androgen deprivation, has been one of the main treatment modalities in the clinical management of prostate cancer patients for more than six decades. In the 1980s, luteinizing hormone-releasing hormone agonists, which reduce testosterone to castration levels, were introduced Also, after the 1980s, nonsteroidal antiandrogens were developed in addition to steroidal antiandrogens. Since then, so-called maximum androgen blockade (MAB)/combined androgen blockade (CAB), which is a combination of surgical or medical castration and oral antiandrogens, has been developed. More recently, novel treatment modalities have been developed, such as intermittent androgen suppression, nonsteroidal antiandrogen monotherapy, and alternative antiandrogen therapy after relapse from initial MAB/CAB, The present article focuses on these treatment modalities to review current topics and perspectives with respect to hormone therapy for prostate cancer.