Enzalutamide as a second generation antiandrogen for treatment of advanced prostate cancer

Prostate cancer (PCa) is the most common malignancy, and the third leading cancer-related cause of death among men of the Western world. Upon PCa progression into metastatic disease, androgen deprivation therapy is applied as the first-line treatment, and has been shown to be effective in most patients, leading to a decrease in serum prostate-specific antigen and relief of disease-related symptoms. However, advanced PCa almost inevitably progresses to a castration-resistant state, and is currently regarded as incurable. The large body of evidence indicates that PCa cells remain dependent on androgen receptor (AR) signaling even in an androgen-deprived environment. As such, development of drugs that target AR and AR signaling pathways have become one of the major milestones in treatment of castration-resistant PCa (CRPC). Nevertheless, currently available therapies that target AR signaling are still regarded as palliative and more potent therapies are in great need. Over the past few years, a wide range of novel therapies has entered clinical trial for treatment of CRPC, including androgen synthesis inhibitors (abiraterone acetate), chemotherapeutic agents (docetaxel and cabazitaxel), and immunotherapies (sipuleucel-T). In this context, enzalutamide (previously referred to as MDV3100) is a novel second generation antiandrogen that has been demonstrated to significantly improve survival in men with metastatic CRPC in several clinical trials. In this paper we summarize recently completed and ongoing clinical trials of enzalutamide, and briefly discuss the efficacy of the novel antiandrogen therapy and its limitations for treatment of CRPC

Interaction between c-jun and Androgen Receptor Determines the Outcome of Taxane Therapy in Castration Resistant Prostate Cancer

Taxane based chemotherapy is the standard of care treatment in castration resistant prostate cancer (CRPC). There is convincing evidence that taxane therapy affects androgen receptor (AR) but the exact mechanisms have to be further elucidated. Our studies identified c-jun as a crucial key player which interacts with AR and thus determines the outcome of the taxane therapy given. Docetaxel (Doc) and paclitaxel (Pac) agents showed different effects on LNCaP and LNb4 evidenced by alteration in the protein and mRNA levels of c-jun, AR and PSA. Docetaxel-induced phophorylation of c-jun occurred before JNK phosphorylation which suggests that c-jun phosphorylation is independent of JNK pathways in prostate cancer cells. A xenograft study showed that mice treated with Pac and bicalutamide showed worse outcome supporting our hypothesis that upregulation of c-jun might act as a potent antiapoptotic factor. We observed in our in vitro studies an inverse regulation of PSA- and AR-mRNA levels in Doc treated LNb4 cells. This was also seen for kallikrein 2 (KLK 2) which followed the same pattern. Given the fact that response to taxane therapy is measured by PSA decrease we have to consider that this might not reflect the true activity of AR in CRPC patients

Multiple Cellular Mechanisms Related to Cyclin A1 in Prostate Cancer Invasion and Metastasis

BACKGROUND: Cyclin A1 is a cell cycle regulator that has been implicated in the progression of prostate cancer. Its role in invasion and metastasis of this disease has not been characterized. METHODS: Immunohistochemistry and cDNA microarray analyses were used to assess protein and mRNA expression of cyclin A1 and proteins with roles in metastasis, including vascular endothelial growth factor (VEGF), metalloproteinase 2 (MMP2), and MMP9, in human prostate cancer. Transient transfection and infection with viral vectors expressing cyclin A1 and short hairpin RNA (shRNA) targeting cyclin A1 were used to study the effects of altered cyclin A1 expression in PC3 prostate cancer cells. The BrdU assay, annexin V staining, and invasion chambers were used to examine cyclin A1 effects on proliferation, apoptosis, and invasion, respectively. The role of cyclin A1 and androgen receptor (AR) in transcription of VEGF and MMP2 was assessed by promoter mutation and chromatin immunoprecipitation. The effect of cyclin A1 expression on tumor growth and metastasis was analyzed in a mouse model of metastasis. All statistical tests were two-sided. RESULTS: Cyclin A1 protein and mRNA expression were statistically significantly higher in prostate cancers than in adjacent benign tissues. A statistically significant correlation between expression of cyclin A1 and of MMP2, MMP9, and VEGF was observed in prostate tumors from 482 patients (P values from Spearman rank correlation tests < .001). PC3 cells that overexpressed cyclin A1 showed increased invasiveness, and inhibition of cyclin A1 expression via shRNA expression reduced invasiveness of these cells. Eight of 10 mice (80%) bearing PC3 cells overexpressing cyclin A1 had infiltration of tumor cells in lymph node, liver, and lung, but all 10 mice bearing tumors expressing control vector were free of liver and lung metastases and only one mouse from this group had lymph node metastasis (P values from Fisher exact tests < .001). Cyclin A1, in concert with AR, bound to and increased expression from the VEGF and MMP2 promoters. CONCLUSIONS: Cyclin A1 contributes to prostate cancer invasion by modulating the expression of MMPs and VEGF and by interacting with AR

Expression of Serotonin Receptors 5-HT1A, 5-HT1B, 5-HT2B and 5-HT4 in Ovary and in Ovarian Tumours.

BACKGROUND: Recently we have shown that serotonin receptors may be involved in prostate cancer development. In ovarian carcinogenesis, oestrogen may play a role. As oestrogen seems to mediate at least some of its biological effects through serotonin, we decided to evaluate if serotonin receptors are expressed in ovary and in ovarian tumours and if the expression is correlated to ovarian tumour development. MATERIALS AND METHODS: An immunohistochemical study of the serotonin (5-HT) receptors 5-HTR1A, 5-HTR1B, 5-HTR2B and 5-HTR4 in frozen samples of ovary, and benign, borderline and invasive ovarian tumours was performed. RESULTS: Expression of all four serotonin receptors was strong to intermediate in the ovarian epithelium. In benign and non-invasive cancer cells, strong staining was seen, while in invasive cancer cells, decreased expression was observed. For 5-HTR2B, the decrease was correlated to dissemination of the disease. For none of the serotonin receptors was the expression correlated to survival. In the stromal part, a variable immunoreactivity was observed that was strongest for 5-HTR2B in both ovary and tumours. Staining of blood vessels was observed in ovary and all tumour groups for 5-HTR2B, but only occasionally was a weak expression seen for 5-HTR1A, 5-HTR1B and 5-HTR4. CONCLUSION: The staining pattern of serotonin receptors in ovary indicates their functional role in ovarian physiology. In ovarian tumours, the expression is in harmony with a tumour suppressor role in ovarian carcinogenesis, which is supported by observations in the literature. Further studies are necessary to resolve the connection between serotonin and ovarian tumour development

Functional in vitro characterisation of the androgen receptor GGN polymorphism.

Superior androgen receptor (AR) function in subjects carrying a GGN repeat length of 23 (GGN23) has been indicated in vivo. Therefore, the activity of the AR carrying GGN23 combined with CAG22 was compared to the AR with GGN10, 24 and 27, respectively, in the presence of 0.1-100 nM testosterone or DHT. At 100 nM DHT, GGN24 showed 35% lower transactivating activity (95% [CI]: 20-50%) than GGN23. GGN10 and GGN27 also showed significantly less AR activity than GGN23 (mean differences [95% CI]: 54% [40-68%] and 58% [39-78%], respectively). The same trend was also observed at lower DHT concentrations. In response to R 188 1, GGN23 activity was significantly higher than for other lengths. ARs with other glutamine numbers than 23 have lower transactivating capacity in response to both testosterone and DHT. Congenital malformations and other signs of hypoandrogenism in subjects with AR gene GGN lengths other than 23 could, hence, be related to a lower AR activity

Experimental in vivo model to evaluate the impact of Cernitin™ on pain response on induced chronic bladder inflammation

Objective: Inflammation of the urinary bladder may cause burdensome pain also called bladder pain syndrome (BPS). A limitation in understanding BPS pathophysiology is the lack of appropriate preclinical model. Previously published clinical and preclinical studies revealed positive impact of Cernitin™ on pain relief in chronic prostatitis. The objective of this study was to evaluate the effects of Cernitin™ on induced inflammation of the urinary bladder in rats. We also sought to identify biomarkers which might play a role in the management of BPS. Materials and methods: Cystitis was induced by injection of cyclophosphamide (CYP) in female rats. Thereafter, animals were randomly divided into four treatment groups and two control groups. Evaluation of pain scores was assessed by von Frey assay. Expression of pain- and pro-inflammatory biomarkers was determined by enzyme-linked immunosorbent assay (ELISA) and immunohistochemistry. Results: Treatments with Cernitin™ displayed significant anti-nociceptive effects on CYP-induced visceral pain (p <.01). In contrast, vehicle-treated animals showed high pain score even at the lowest force. Furthermore, results of ELISA showed that Cernitin™-treated animals had significantly reduced levels of COX-2 (T60, p <.01; GBX, p <.05) in bladder tissue homogenate. Immunohistochemical (IHC) staining of bladder tissues showed that Cernitin™-treated animals exhibited less CD45-positive cells, while massive CD45-positive cells infiltration was detected in vehicle-treated animals. IHC also revealed lower SP and PGD2 expression levels in Cernitin™-treated tissues. Conclusions: Cernitin™ components reduced pain score and inflammatory marker COX-2. Our findings suggest a potential therapeutic role for Cernitin™ in the management of BPS

The effect of a novel botanical agent TBS-101 on invasive prostate cancer in animal models.

BACKGROUND: Traditional Botanical Supplement-101 (TBS-101) is a newly developed proprietary botanical agent containing seven standardized botanical extracts, including: Panax ginseng, cranberry, green tea, grape skin, grape seed, Ganoderma lucidum and chamomile. Each of the components has been consumed either in the regular diet or as natural supplement. When used as a single agent, each of these seven botanicals has been implicated in chemoprevention and therapy in various types of cancer. The anticancer effect of TBS-101, with the specific combination of these anti-cancer botanicals for the treatment of prostate cancer (PCa), has not been tested. MATERIALS AND METHODS: The IC(50) and the effect of TBS-101 on the proliferation and apoptosis of PC-3 cells were determined. Tumor xenograft mice were generated by subcutaneously implanting PC-3 cells into mice and tumors were allowed to grow to different sizes before starting the treatment. The effects of TBS-101 on tumor growth were assessed by measuring tumor size and by histological, pathological and immunohistochemical analyses. A basic toxicity study was performed to test the tolerance of the mice to high doses of TBS-101. RESULTS: Treatment of the PC-3 cells with TBS-101 resulted in a dose-dependent inhibition of cell growth, with an IC(50) of 1.4 microg/ml. A concomitant induction of apoptosis in PC-3 cells treated with TBS-101 was also observed. Upon the treatment with TBS-101, all three groups of mice bearing moderate or large tumors showed significant inhibition of tumor growth and invasion. In contrast, control mice treated with vehicle alone had significant tumor growth and lymph node metastasis. In the basic toxicity studies, high doses of TBS-101 exerted no toxicity in healthy or tumor-bearing mice. CONCLUSION: The natural botanical agent TBS-101 has a good safety profile and significant anticancer activities in hormone-refractory PC-3 cells and large aggressive PC-3 tumors in a xenograft mouse model and has great potential for the treatment of aggressive prostate cancer

Neuroendocrine cells and nerves in the prostate of the guinea pig: effects of peripheral denervation and castration

BACKGROUND: Neuroendocrine (NE) cells and nerves in the prostate gland are thought to play a central role in the regulation of growth, cellular differentiation and homeostasis of secretory activity. The objective of this experimental study was to describe the effects of peripheral denervation and castration on NE cells and nerves in the guinea pig prostate. METHODS: Guinea pigs underwent sham-operation, unilateral and bilateral hypogastric nerve resection, extirpation of the right anterior major pelvic ganglion (AMPG), autotransplantation of prostatic tissue and castration. Cryostat sections of prostatic tissue were examined with immunohistochemistry by using serotonin (5-HT) and chromogranin A (CgA) and various neuropeptides. RESULTS: The number of 5-HT-IR NE cells was four-fold higher than CgA-IR NE cells. The innervation pattern was uniform throughout the gland with subepithelial nerves in close proximity to NE cells. Autotransplants of prostatic tissue showed total loss of nerves, but the number and morphology of 5-HT-IR NE cells were unaltered. Extirpation of the right AMPG showed significant reduction in prostate weight, decreased density of nerve terminals in the superior part of the ipsilateral prostate, whereas the number and morphological feature of 5-HT-IR NE cells remained unaffected in the entire prostate. Castration induced atrophy of the gland with a significant reduction in weight (unpaired t-test, P < 0.001), but without effect upon 5-HT-IR NE cells. CONCLUSIONS: The guinea pig seems to be a useful animal model for studies on the role of the NE cells in the prostate. NE cells seem to be independent of innervation and androgens. It seems that other factors influence the NE cell population to a greater extent

Expression of somatostatin receptor subtypes 2 and 4 in human benign prostatic hyperplasia and prostatic cancer.

BACKGROUND: The presence of receptor subtypes for the inhibitory peptide somatostatin in prostatic tissue has been a controversial issue with conflicting reports. To elucidate whether prostatic epithelial cells express mRNA for somatostatin receptor (SSTR) subtype 2 and 4, we have investigated the localization of SSTR2 and SSTR4 transcripts in prostatic tissues by in situ hybridization. METHODS: Nonradioactive in situ hybridization was performed with specific fluorescein-labeled SSTR2 and SSTR4 riboprobes on consecutive sections of benign prostatic hyperplasia (BPH) and prostate cancer tissues. RESULTS: We report, for the first time, tissue localization of SSTR2 and SSTR4 mRNA in BPH and malignant cells of human prostate. Hybridization signals for SSTR4 mRNA transcripts were confined to the prostatic epithelium (12 of 16 BPH cases, and in 12 of 13 carcinoma cases), whereas SSTR2 transcripts were predominantly localized in the stromal compartment but also were detectable in epithelial cells in a significant number of specimens (11 of 17 BPH cases, and in 12 of 14 carcinoma cases). Furthermore, the staining intensity for SSTR2 and SSTR4 transcripts is stronger in malignant cells compared with adjacent BPH epithelium. CONCLUSION: The data presented suggest that the expression of SSTR2 and SSTR4 transcripts is up-regulated in malignant cells and that not only SSTR2 agonists, but also compounds targeting the SSTR4 subtype may have a potential role in the treatment of prostate cancer

Long-term testosterone stimulation induces hyperplasia in the guinea-pig prostate.

The relation between supraphysiologic circulating testosterone levels and prostatic diseases is unclear and difficult to study in men. Animal models may be advantageous. Based on a pilot study, testosterone enantate 50 mg (n=12) or 25 mg (n=12) was administered to guinea-pigs intramuscularly every 3 weeks, for either 7 or 14 months. The histopathology of the prostate was described. Epithelial hyperplasia was found in 14/21 animals receiving testosterone and in 7/12 very old animals, but no such changes were found in the sham or castrated animals. Testosterone stimulation seems to induce epithelial hyperplasia, but not cancer, in the guinea-pig prostate