New Agents for the Management of Castration-Resistant Prostate Cancer

Structure-based discovery of selective CYP17A1 inhibitors for Castration-resistant prostate cancer treatment

Prostate cancer (PCa) is the most common malignancy found in men and the second leading cause of cancer-related death worldwide. Castration-resistant PCa (CRPC) is defined by PCa cells that stop responding to hormone therapy. Cytochrome P450 17α-hydroxylase/17,20-lyase (CYP17A1) plays a critical role in the biosynthesis of androgens in humans. Androgen signaling cascade is a principal survival pathway for PCa cells and androgen-deprivation therapy (ADT) remains the key treatment for patients marked with locally advanced and metastatic PCa cells. Available synthetic drugs have been reported for toxicity, drug resistance, and decreasing efficacy. Thus, the design of novel selective inhibitors of CYP17A1 lyase would help circumvent associated side effects and improve pharmacological activities. Therefore, we employed structural bioinformatics techniques via molecular docking; molecular mechanics generalized born surface area (MM-GBSA), molecular dynamics (MD) simulation, and pharmacokinetic study to identify putative CYP17A1 lyase inhibitors. The results of the computational investigation showed that the Prunus dulcis compounds exhibited higher binding energy than the clinically approved abiraterone acetate. The stability of the ligand with the highest binding affinity (quercetin-3-o-rutinoside) was observed during MD simulation for 10 ns. Quercetin-3-o-rutinoside was observed to be stable within the active site of CYP17A1Lyase throughout the simulation period. The result of the pharmacokinetic study revealed that these compounds are promising therapeutic agents. Collectively, this study proposed that bioactive compounds from P. dulcis may be potential selective inhibitors of CYP17A1Lyase in CRPC treatments.

A New Old Target: Androgen Receptor Signaling and Advanced Prostate Cancer

Owing to the development of multiple novel therapies, there has been major progress in the treatment of advanced prostate cancer over the last two decades; however, the disease remains invariably fatal. Androgens and the androgen receptor (AR) play a critical role in prostate carcinogenesis, and targeting the AR signaling axis with abiraterone, enzalutamide, darolutamide, and apalutamide has improved outcomes for men with this lethal disease. Targeting the AR and elucidating mechanisms of resistance to these agents remains central to drug development efforts. This review provides an overview of the evolution and current approaches for targeting the AR in advanced prostate cancer. It describes the biology of AR signaling, explores AR-targeting resistance mechanisms, and discusses future perspectives and promising novel therapeutic strategies. Expected final online publication date for the Annual Review of Pharmacology and Toxicology, Volume 62 is January 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Integrated analysis of the prostate cancer small-nucleolar transcriptome reveals SNORA55 as a driver of prostate cancer progression

Metastasis is the primary cause of death in prostate cancer (PCa) patients. Small nucleolar RNAs (snoRNAs) have long been considered "housekeeping" genes with no relevance for cancer biology. Emerging evidence has challenged this assumption, suggesting that snoRNA expression is frequently modulated during cancer progression. Despite this, no study has systematically addressed the prognostic and functional significance of snoRNAs in PCa. We performed RNA Sequencing on paired metastatic/non-metastatic PCa xenografts derived from clinical specimens. The clinical significance of differentially expressed snoRNAs was further investigated in two independent primary PCa cohorts (131 and 43 patients, respectively). The snoRNA demonstrating the strongest association with clinical outcome was quantified in PCa patient-derived serum samples and its functional relevance was investigated in PCa cells via gene expression profiling, pathway analysis and gene silencing. Our comparison revealed 21 differentially expressed snoRNAs in the metastatic vs. non-metastatic xenografts. Of those, 12 were represented in clinical databases and were further analyzed. SNORA55 emerged as a predictor of shorter relapse-free survival (results confirmed in two independent databases). SNORA55 was reproducibly detectable in serum samples from PCa patients. SNORA55 silencing in PCa cell lines significantly inhibited cell proliferation and migration. Pathway analysis revealed that SNORA55 expression is significantly associated with growth factor signaling and pro-inflammatory cytokine expression in PCa. Our results demonstrate that SNORA55 up-regulation predicts PCa progression and that silencing this non-coding gene affects PCa cell proliferation and metastatic potential, thus positioning it as both a novel biomarker and therapeutic target.

Discovery of the Selective CYP17A1 Lyase Inhibitor BMS-351 for the Treatment of Prostate Cancer

Efforts to identify a potent, reversible, nonsteroidal CYP17A1 lyase inhibitor with good selectivity over CYP17A1 hydroxylase and CYPs 11B1 and 21A2 for the treatment of castration-resistant prostate cancer (CRPC) culminated in the discovery of BMS-351 (compound 18), a pyridyl biaryl benzimidazole with an excellent in vivo profile. Biological evaluation of BMS-351 at a dose of 1.5 mg in castrated cynomolgus monkeys revealed a remarkable reduction in testosterone levels with minimal glucocorticoid and mineralcorticoid perturbation. Based on a favorable profile, BMS-351 was selected as a candidate for further preclinical evaluation.

Enhanced Sensitivity to Sunitinib by Inhibition of Akt1 Expression in Human Castration-resistant Prostate Cancer PC3 Cells Both In Vitro and In Vivo

OBJECTIVE

To investigate whether antitumor activity of sunitinib is enhanced by silencing Akt1 in a human castration-resistant prostate cancer PC3 model.

MATERIALS AND METHODS

We initially established PC3 in which the expression vector containing a short hairpin ribonucleic acid targeting Akt1 was introduced (PC3/sh-Akt1). Changes in various phenotypes of PC3/sh-Akt1 after treatment with sunitinib were compared with those of PC3 transfected with control vector alone (PC3/C) both in vitro and in vivo.

RESULTS

When cultured in the standard medium, in vitro growth of PC3/sh-Akt1 was almost similar to that of PC3/C. However, compared with PC3/C, PC3/sh-Akt1 showed a significantly higher sensitivity to sunitinib, accompanying impaired phosphorylation of p44/42 mitogen-activated protein kinase, downregulation of Bcl-2, and upregulation of Bax. In addition, treatment with sunitinib significantly suppressed the migration ability of PC3/sh-Akt1 compared with that of PC3/C. In vivo, administration of sunitinib induced the significantly marked growth inhibition of PC3/sh-Akt1 compared with that of PC3/C, and apoptotic index in PC3/sh-Akt1 tumor in mice treated with sunitinib was significantly greater than that in PC3/C tumor.

CONCLUSION

Combined treatment with Akt1 inhibitor and sunitinib could be a promising therapeutic approach for men with castration-resistant prostate cancer.

CK2-NCoR signaling cascade promotes prostate tumorigenesis

The aberrant expressions of casein kinase 2 (CK2) was found in prostate cancer patient and cell lines, but little is known of the detailed mechanisms implicated in prostate tumorigenesis. In this study, we report that both CK2 activity and CK2-mediated NCoR phosphorylation are significantly elevated in the androgen-independent prostate cancer cell line DU145 and PC-3 compared with RWPE1 and LNCaP cells. Increased phosphorylation inversely correlates with the mRNA level of the NCoR-regulated gene, interferon-γ-inducible protein 10 (IP-10). CK2 inhibition abrogated NCoR phosphorylation, IP-10 transcriptional repression, and the invasion activity of PC-3 cells. Inhibition of the CK2-NCoR network significantly reduced in vivo PC-3 cell tumorigenicity, likely due to transcriptional derepression of IP-10. Clinicopathological analyses revealed that increased CK2-mediated NCoR phosphorylation significantly correlates with poor survival among prostate cancer patients. These findings elucidate a CK2-modulated oncogenic cascade in prostate tumorigenesis.

Characterization and sub-cellular localization of SS1R, SS2R, and SS5R in human late-stage prostate cancer cells: effect of mono- and bi-specific somatostatin analogs on cell growth

Somatostatin (SST) and SST receptors (SS1R, SS2R, SS3R, SS4R and SS5R) appear to play a significant role in the progression of human prostate cancer (PCa), which is associated with heterogeneity of SSRs expression and specific cell localization as we already demonstrated in the LNCaP cell line, an in vitro model of human androgen-dependent PCa. In this study, PC-3 and DU-145 human castration-resistant PCa cells were found to express all SSRs, while LNCaP expressed all but SS4R. A 48-h treatment with BIM-23244 (SS2R/SS5R) or BIM-23926 (SS1R) SST analogs was more effective in inhibiting cell proliferation, compared to BIM-23120 (SS2R), BIM-23206 (SS5R) and BIM-23704 (SS1R/SS2R). BIM-23926 (SS1R) treatment increased the amount of p21 and decreased phosphorylated (p) ERK1/2. BIM-23244 (SS2R/SS5R) led to p21 increment only in PC-3 cells, and to pERK1/2 reduction in both cell lines. SS1R/SS2R and SS2R/SS5R receptor dimers were natively present on cell membrane and their amount was increased by BIM-23704 (SS1R/SS2R) or BIM-23244 (SS2R/SS5R) treatment, respectively. SS1R, SS2R and SS5R were differently distributed among nuclear, lysosomal and microsomal compartment, according to their different recycling dynamics. These results show that, in PC-3, DU-145 and LNCaP cells, activation of SS1R and SS2R/SS5R leads to relevant antiproliferative effects.

Chemokines and chemokine receptors as promoters of prostate cancer growth and progression

Prostate cancer (CaP) is estimated to be first in incidence among cancers, with more than 240,000 new cases in 2012 in the United States. Chemokines and their receptors provide survival, proliferation, and invasion characteristics to CaP cells in both primary sites of cancer and metastatic locations. The emerging data demonstrate that many chemokines and their receptors are involved in the multistep process of CaP, leading to metastasis, and, further, that these factors act cooperatively to enhance other mechanisms of tumor cell survival, growth, and metastasis. Changes of chemokine receptor cohorts may be necessary to activate tumor-promoting signals. Chemokine receptors can activate downstream effectors, such as mitogen-activated protein kinases, by complex mechanisms of ligand-dependent activation of cryptic growth factors; guanosine triphosphate-binding, protein-coupled activation of survival kinases; or transactivation of other receptors such as ErbB family members. We describe vanguard research in which more than the classic view of chemokine receptor biology was clarified. Control of chemokines and inhibition of their receptor activation may add critical tools to reduce tumor growth, especially in chemo-hormonal refractory CaP that is both currently incurable and the most aggressive form of the disease, accounting for most of the more than 28,000 annual deaths.