Hormonal therapy of prostate cancer

Hormone sensitive protocol for metastatic prostate cancer, an update

To review and update last protocols in hormone sensitive metastatic prostate cancer for improving clinical management in routine. Evidence analysis available about recent updates protocols in hormone sensitive metastatic prostate cancer according to expert panel of clinicians about this field. A nominal consensus group for unify and improve the recommendations to the management of sensitive metastatic prostate cancer patients is currently needed. This document unifies and improve the management of patients with hormone sensitive metastatic prostate cancer, with a methodology that combines data quantitative and qualitative and based on the participation of a broad scientific committee appointed by the Spanish Association of Urology.

Synthesis, Characterization, and Preclinical Evaluation of a Small-Molecule Prostate-Specific Membrane Antigen-Targeted Monomethyl Auristatin E Conjugate

Prostate cancer is the second most common type of cancer among men. Its main method of treatment is chemotherapy, which has a wide range of side effects. One of the solutions to this challenge is targeted delivery to prostate cancer cells. Here we synthesized a novel small-molecule PSMA-targeted conjugate based on the monomethyl auristatin E. Its structure and conformational properties were investigated by NMR spectroscopy. Cytotoxicity, intracellular reactive oxygen species induction, and stability under liver microsomes and P450-cytochrome species were investigated for this conjugate. The conjugate demonstrated 77-85% tumor growth inhibition levels on 22Rv1 (PSMA (+)) xenografts, compared with a 37% inhibition level on PC-3 (PSMA (-)) xenografts, in a single dose of 0.3 mg/kg and a sufficiently high therapeutic index of 21. Acute, chronic, and subchronic toxicities and pharmacokinetics have shown that the synthesized conjugate is a promising potential agent for the chemotherapy of prostate cancer.

Treatment strategy for metastatic prostate cancer with extremely high PSA level: reconsidering the value of vintage therapy

The prognostic significance of initial prostate-specific antigen (PSA) level for metastatic prostate cancer remains uncertain. We investigated the differences in prognosis and response to hormonal therapies of metastatic prostate cancer patients according to initial PSA levels. We analyzed 184 patients diagnosed with metastatic prostate cancer and divided them into three PSA level groups as follows: low (<100 ng ml⁻¹), intermediate (100–999 ng ml⁻¹), and high (≥1000 ng ml⁻¹). All patients received androgen deprivation therapy (ADT) immediately. We investigated PSA progression-free survival (PFS) for first-line ADT and overall survival (OS) within each of the three groups. Furthermore, we analyzed response to antiandrogen withdrawal (AW) and alternative antiandrogen (AA) therapies after development of castration-resistant prostate cancer (CRPC). No significant differences in OS were observed among the three groups (P = 0.654). Patients with high PSA levels had significantly short PFS for first-line ADT (P = 0.037). Conversely, patients in the high PSA level group had significantly longer PFS when treated with AW than those in the low PSA level group (P = 0.047). Furthermore, patients with high PSA levels had significantly longer PFS when provided with AA therapy (P = 0.049). PSA responders to AW and AA therapies had significantly longer survival after CRPC development than nonresponders (P = 0.011 and P < 0.001, respectively). Thus, extremely high PSA level predicted favorable response to vintage sequential ADT and AW. The current data suggest a novel aspect of extremely high PSA value as a favorable prognostic marker after development of CRPC.

Regulation of HMGB3 by antitumor miR-205-5p inhibits cancer cell aggressiveness and is involved in prostate cancer pathogenesis

Our recent determination of a microRNA (miRNA) expression signature in prostate cancer (PCa) revealed that miR-205-5p was significantly reduced in PCa tissues and that it acted as an antitumor miRNA. The aim of this study was to identify oncogenic genes and pathways in PCa cells that were regulated by antitumor miR-205-5p. Genome-wide gene expression analyses and in silico miRNA database searches showed that 37 genes were putative targets of miR-205-5p regulation. Among those genes, elevated expression levels of seven in particular (HMGB3, SPARC, MKI67, CENPF, CDK1, RHOU, and POLR2D) were associated with a shorter disease-free survival in a large number of patients in the The Cancer Genome Atlas (TCGA) database. We focused on high-mobility group box 3 (HMGB3) because it was the most downregulated by ectopic expression of miR-205-5p in PC3 cells and its expression was involved in PCa pathogenesis. Luciferase reporter assays showed that HMGB3 was directly regulated by miR-205-5p in PCa cells. Knockdown studies using si-HMGB3 showed that expression of HMGB3 enhanced PCa cell aggressiveness. Overexpression of HMGB3/HMGB3 was confirmed in naive PCa and castration-resistant PCa (CRPC) clinical specimens. Novel approaches to analysis of antitumor miRNA-regulated RNA networks in PCa cells may provide new insights into the pathogenic mechanisms of the disease.

Binding of a type 1 RIP and of its chimeric variant to phospholipid bilayers: evidence for a link between cytotoxicity and protein/membrane interactions

Ribosome-inactivating proteins (RIPs) are enzymes, almost all identified in plants, able to kill cells by depurination of rRNAs. Recently, in order to improve resistance to proteolysis of a type 1 RIP (PD-L4), we produced a recombinant chimera combining it with a wheat protease inhibitor (WSCI). Resulting chimeric construct, named PD-L4UWSCI, in addition to present the functions of the two domains, shows also an enhanced cytotoxic action on murine cancer cells when compared to PD-L4. Since different ways of interaction of proteins with membranes imply different resulting effects on cells, in this study we investigate conformational stability of PD-L4 and PD-L4UWSCI and their interaction with membrane models (liposomes). Circular dichroism analysis and differential scanning calorimetry measurements indicate that PD-L4 and PD-L4UWSCI present high and similar conformational stability, whereas analysis of their binding to liposomes, obtained by isothermal titration calorimetry and differential scanning calorimetry, clearly indicate that chimera is able to interact with biomembranes more effectively. Overall, our data point out that WSCI domain, probably because of its flexibility in solution, enhances the chimeric protein interaction with membrane lipid surfaces without however destabilizing the overall protein structure. Analysis of interactions between RIPs or RIP based conjugates and lipid surfaces could provide novel insights in the search of more effective selective membrane therapeutics.

Gonadotropin‑releasing hormone inhibits the proliferation and motility of nasopharyngeal carcinoma cells

Gonadotropin-releasing hormone (GnRH), or its analogues have been demonstrated to exhibit anti-proliferative effects on tumour cells in ovarian, endometrial and breast cancer through GnRH-receptors (GnRH-R). However, the role of GnRH in nasopharyngeal carcinoma (NPC) remains to be elucidated. In order to investigate the effects of GnRH in NPC, the present study examined the expression of the GnRH-R transcript in NPC and investigated the phenotypic changes in HK1 cells, a recurrent NPC-derived cell line, upon receiving GnRH treatment. Firstly, the GnRH-R transcript was demonstrated in the NPC cell lines and four snap frozen biopsies using reverse transcription-quantitative polymerase chain reaction. In addition, immunohistochemistry revealed the expression of GnRH-R in two of the eight (25%) NPC specimens. Treatment with GnRH induced a rapid increase in intracellular ionised calcium concentration in the NPC cells. GnRH and its agonists, triptorelin and leuprolide, exerted anti-proliferative effects on the NPC cells, as determined using an MTS assay. GnRH did not induce any cell cycle arrest in the HK1 cells under the conditions assessed in the present study. Time-lapse imaging demonstrated a reduction in cell motility in the GnRH-treated cells. In conclusion, GnRH, or its analogues may have antitumour effects on NPC cells. The consequences of alterations in the levels of GnRH on the progression of NPC require further examination.

Regulation of local steroidogenesis in the brain and in prostate cancer: lessons learned from interdisciplinary collaboration

Sex steroids play critical roles in the regulation of the brain and many other organs. Traditionally, researchers have focused on sex steroid signaling that involves travel from the gonads via the circulation to intracellular receptors in target tissues. This classic concept has been challenged, however, by the growing number of cases in which steroids are synthesized locally and act locally within diverse tissues. For example, the brain and prostate carcinoma were previously considered targets of gonadal sex steroids, but under certain circumstances, these tissues can upregulate their steroidogenic potential, particularly when circulating sex steroid concentrations are low. We review some of the similarities and differences between local sex steroid synthesis in the brain and prostate cancer. We also share five lessons that we have learned during the course of our interdisciplinary collaboration, which brought together neuroendocrinologists and cancer biologists. These lessons have important implications for future research in both fields.

Role of YY1 in the pathogenesis of prostate cancer and correlation with bioinformatic data sets of gene expression

Current treatments of various cancers include chemotherapy, radiation, surgery, immunotherapy, and combinations. However, there is a need to develop novel diagnostic and therapeutic treatments for unresponsive patients. These may be achieved by the identification of novel diagnostic and prognostic biomarkers which will help in the stratification of patients' initial responses to particular treatments and circumvent resistance, relapses, metastasis, and death. We have been investigating human prostate cancer as a model tumor. We have identified Yin Yang 1 (YY1), a dysregulated transcription factor, whose overexpression correlated with tumor progression as well as in the regulation of drug resistance and the development of EMT. YY1 expression is upregulated in human prostate cancer cell lines and tissues. We postulated that YY1 may be a potential biomarker in prostate cancer for patients' stratification as well as a novel target for therapeutic intervention. We used Bioinformatic gene RNA array datasets for the expression of YY1 in prostate tumor tissues as compared to normal tissues. Interestingly, variations on the expression levels of YY1 mRNA in prostate cancer were reported by different investigators. This mini review summarizes the current reported studies and Bioinformatic analyses on the role of YY1 in the pathogenesis of prostate cancer.

The type of patients who would benefit from anti-androgen withdrawal therapy: could it be performed safely for aggressive prostate cancer?

This study was designed to detect the factors that were significantly associated with the results of anti-androgen withdrawal (AAWD) therapy, and to examine whether patients with aggressive prostate cancer demonstrating a short prostate-specific antigen (PSA)-doubling time (DT) could benefit from it without even greater exacerbation of the disease. We conducted a retrospective chart review study of 121 patients who received AAWD therapy due to failed combined androgen blockade (CAB) therapy. A reduction in the serum PSA level after AAWD was observed in 35 patients (28.9 %), and a greater than 50 % decrease from the baseline serum PSA level was observed in 16 patients (13.2 %). Shortening of PSA-DT after AAWD was observed in 48 patients (39.7 %). Univariate and multivariate analyses demonstrated that only a long duration of prior anti-androgen treatment was selected as a significant predictor for a good response to AAWD therapy. With respect to exacerbation after AAWD, we found that patients with a short baseline PSA-DT conversely had a low risk of subsequent shortening of PSA-DT. Using these two factors, we could stratify the patients into four groups, and patients with prior duration of anti-androgen >18 months and PSA-DT ≤3 months demonstrated the best results with a good response rate (67.9 %) and a low risk for a worsening of the disease (14.3 %). We conclude that AAWD would be effective especially for patients whose cancer progressed rapidly (short PSA-DT) after a long stable period under CAB and should be recommended before embarking on the next therapeutic maneuver.

Pharmacokinetic/pharmacodynamic model of the testosterone effects of triptorelin administered in sustained release formulations in patients with prostate cancer

The objectives of the current work were to develop a predictive population pharmacokinetic (PK)/pharmacodynamic (PD) model for the testosterone (TST) effects of triptorelin (TRP) administered in sustained-release (SR) formulations to patients with prostate cancer and determine the minimal required triptorelin serum concentration (C(TRP_min)) to keep the testosterone levels of the patients below or equal to the level of castration (TST ≤ 0.5 ng/ml). A total of eight healthy male volunteers and 74 patients with prostate cancer received one or two doses of triptorelin injected subcutaneously or intramuscularly. Five different triptorelin formulations were tested. Pharmacokinetic (serum concentration of triptorelin) and pharmacodynamic (TST levels in serum) data were analyzed by using the population approach with NONMEM software (http://www.iconplc.com/technology/products/nonmem/). The PK/PD model was constructed by assembling the agonist nature of triptorelin with the competitive reversible receptor binding interaction with the endogenous agonist, a process responsible for the initial and transient TST flare-up, and triggering down-regulation mechanisms described as a decrease in receptor synthesis. The typical population values of K(D), the receptor equilibrium dissociation constant of triptorelin, and C(TRP_min) to keep 95% of the patients castrated were 0.931 and 0.0609 ng/ml, respectively. The semimechanistic nature of the model renders the predictions of the effect of triptorelin on TST possible regardless the type of SR formulation administered, while exploring different designs during the development of new delivery systems.

Comparison of serum testosterone levels in prostate cancer patients receiving LHRH agonist therapy with or without the removal of the prostate

INTRODUCTION

: The prostate secretes enzymes and nutrients to promote sperm motility. Recent reports suggest that the prostate may also secrete testosterone, which is believed to be a fuel for prostate tumour growth. The aim of this study was to determine if a difference in serum testosterone levels exists between men on luteinizing hormone releasing-hormone (LHRH) agonists who have undergone radical prostatectomy, radiation or hormone therapy as primary prostate cancer treatment.

METHODS

: Serum testosterone levels were evaluated in 165 consecutive prostate cancer patients using LHRH analogues for >3 months. We excluded patients receiving either radiation or chemotherapy at time of time of testosterone measurement. Patients were classified based on primary treatment: (1) radical prostatectomy; (2) radiation; or (3) primary hormone therapy. We used one-way ANOVA to compare testosterone levels. Pearson correlation was used to correlate testosterone with prostate-specific antigen (PSA) and time on LHRH agonists. Multivariable linear regression was used to predict serum testosterone levels.

RESULTS

: The median (interquartile range) serum testosterone levels were 1.4 (1-1.9), 1.3 (1-1.625) and 1.25 (0.9-1.525) nmol/L for radical prostatectomy, radiation and primary hormone therapy groups, respectively. There was no statistically significant difference in testosterone levels between the groups (p = 0.3). No correlation was found between testosterone and PSA levels or time on LHRH (r = 0.02 and r = 0.01), respectively. Multivariable linear regression showed that none of the clinical variables were predictors of serum testosterone levels.

CONCLUSION

: Our study suggests that primary treatment does not affect serum testosterone levels among men using LHRH analogues.

Conformational analysis of steroid hormone molecules in the lipid environment--a solid-state NMR approach

Solid-state (1)H/(13)C cross-polarization/magic angle spinning (CP/MAS) NMR spectroscopy has been applied to two steroid compounds: dehydroepiandrosterone (DHEA) and spironolactone (SPI), to analyze their conformations at the atomic level. In the absence of lipid, the high-resolution (13)C CP/MAS NMR signals of DHEA and SPI in a powder form reveal multiple patterns, with splittings of 30-160 Hz, indicating the existence of multiple conformations. In the mimic lipid environment formed by mixing 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and 1,2-diheptanoyl-sn-glycero-3-phosphocholine (DHPC) in a molar ratio 3:1, the resulting DHEA and SPI spectra revealed mostly singlet patterns, suggesting that these steroids undergo a conformational change leading to a specific conformation in the lipid environment. Evidence from chemical shift isotropy and anisotropy analysis indicates that DHEA might adopt conformations subtly different from that seen in solution and in the powder form. In conclusion, we demonstrate by solid-state NMR that the structures of DHEA and SPI may adopt slightly different conformations in different chemical environments.

Steroid hormone receptors in cancer development: a target for cancer therapeutics

The steroid hormone receptors (SHRs) are ligand-dependent intracellular transcription factors that are known to influence the development and growth of many human cancers. SHRs pass signals from a steroid/hormone to the target genes by interacting with specific response element DNA sequences and various coregulatory proteins that consists of activators and/or corepressors. Disruptions in physiological functions of SHRs leads to several types of malignancies such as breast cancer, leukemia and lymphoma, prostate cancer, ovarian cancer, and lung cancer among others. Steroids/hormones/SHRs and their coregulators have opened up a unique window for novel steroid-based targeted therapies for cancer. Thus, dysregulation of SHR signaling in cancers compared with normal tissues can be exploited to target drugs that prevent and treat human cancers. In recent years, hormonal therapy has made a major contribution to the treatment of several cancers including reduced recurrence rates and longer survival rates. Development of various steroid receptor modulators and their potential therapeutic efficacies has provided us a great opportunity to effectively manage diseases like cancer in future. In this review article, we have summarized up-to-date knowledge of the role of SHRs in the development and progression of cancers, and potential endocrine-based therapeutic approaches to tackle these diseases.