The resurgence of estrogens in the treatment of castration-resistant prostate cancer

Maintaining bone health by estrogen therapy in patients with advanced prostate cancer: a narrative review

The purpose of androgen deprivation therapy (ADT) in prostate cancer (PCa), using luteinizing hormone-releasing hormone agonists (LHRHa) or gonadotrophin-releasing hormone antagonists, is to suppress the levels of testosterone. Since testosterone is the precursor of estradiol (E2), one of the major undesired effects of ADT is the concomitant loss of E2, causing among others an increased bone turnover and bone loss and an increased risk of osteoporosis and fractures. Therefore, the guidelines for ADT indicate to combine ADT routinely with bone-sparing agents such as bisphosphonates, denosumab or selective estrogen receptor modulators. However, these compounds may have side effects and some require inconvenient parenteral administration. Co-treatment with estrogens is an alternative approach to prevent bone loss and at the same time, to avoid other side effects caused by the loss of estrogens, which is the topic explored in the present narrative review. Estrogens investigated in PCa patients include parenteral or transdermal E2, diethylstilbestrol (DES), and ethinylestradiol (EE) as monotherapy, or high-dose estetrol (HDE4) combined with ADT. Cardiovascular adverse events have been reported with parenteral E2, DES and EE. Encouraging effects on bone parameters have been obtained with transdermal E2 (tE2) and HDE4, in the tE2 development program (PATCH study), and in the LHRHa/HDE4 co-treatment study (PCombi), respectively. Confirmation of the beneficial effects of estrogen therapy with tE2 or HDE4 on bone health in patients with advanced PCa is needed, with special emphasis on bone mass and fracture rate.

Resveratrol inhibits TRAF6/PTCH/SMO signal and regulates prostate cancer progression

Prostate cancer (PC) is one of the most common types of cancers among men, referring to the uncontrolled growth of the prostate gland. It is increasingly recognized that the interaction of the glioma-associated oncogene (GLI) pathway and androgen receptor affects PC progression. Nevertheless, the effects of resveratrol on PC progression via Hedgehog (HH) signaling remain unexplored. In this study, the castration-sensitive and castration-resistant xenograft models in mice are systematically established using two different PC cell lines (LNCaP and PC-3). Further, the Western blotting, immunohistochemistry, MTT, Transwell, and RT-qPCR analyses are performed to verify the mechanistic views of resveratrol on PC and HH signals in vitro and in vivo. Resveratrol showed epithelial-mesenchymal transition (EMT) progression, inhibiting the tumor size and expression levels of vimentin, vascular endothelial growth factor (VEGF), and matrix metalloproteinases (MMP) 7, as well as upregulating the expression profiles the E-cadherin and Annexin 2. Moreover, resveratrol inhibited the hedgehog (HH) signals and tumor necrosis factor receptor (TNFR)-associated factor 6 (TRAF6) levels exhibiting the therapeutic action on castration-sensitive and castration-resistant PC cell lines. In summary, the overexpression of TRAF6 enhanced the viability and EMT progression of cancer cells. The resveratrol could alleviate the TRAF6 effect and regulate the HH signal to affect PC progression.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10616-022-00544-0.

The androgen receptor inhibits transcription of GPER1 by preventing Sp1 and Sp3 from binding to the promoters in prostate cancer cells

G-1, a GPER1 agonist, was shown to inhibit the growth of castration-resistant mouse xenografts but not their parental androgen-dependent tumors. It is currently unknown how the androgen receptor (AR) represses GPER1 expression. Here, we found that two GPER1 mRNA variants (GPER1v2 and GPER1v4) were transcriptionally repressed, not via transcript destabilization, by the androgen-activated AR. Although no AR binding was found in all active promoters near GPER1, data from promoter assays suggested that both variants' promoters were inhibited by androgen treatment. Site-directed mutagenesis on Sp1/Sp3 binding sites revealed their role in supporting the basal expression of GPER1. Knockdown of Sp1 and Sp3 together but not separately repressed GPER1 expression whereas overexpression of both Sp1 and Sp3 together was required to alleviate AR repression of GPER1. Based on the chromatin immunoprecipitation data, Sp3 was found to bind to the promoters prior to the binding of Sp1 and RNA polymerase II. However, the binding of all three transcription factors was inhibited by DHT treatment. Concordantly, DHT treatment induced nuclear interactions between AR and Sp1 or Sp3. Taken together, these results indicate that AR represses transcription of GPER1 by binding to Sp1 and Sp3 independently to prevent their transactivation of the GPER1 promoters.

Phytoestrogens as Potential Antiandrogenic Agents Against Prostate Cancer: An In Silico Analysis

Background:

Prostate cancer is the second most common cancer worldwide. The androgen deprivation therapy or castration leads to the recurrence of castration-resistant prostate cancer after some time. Androgen receptor is one of the most promising targets for the treatment of prostate cancer. The health benefits of phytoestrogens led us to explore them for their androgen receptor inhibition potential that may lead to inhibition of initiation and progression of prostate cancer.

Methods:

Protein-ligand interaction plays a central role in structure-based drug design, so we screened 23 phytoestrogens for their binding affinity to the androgen receptor using the molecular docking approach. These phytoestrogens were also tested for their ADME and toxicity profiles using the software.

Results:

Based on binding affinity, interacting amino acid residues, pharmacokinetics and toxicity profile, four phytoestrogens, namely naringenin, luteolin, hesperetin, and biochanin A were shortlisted as lead molecules.

Conclusion:

Therefore, our study has shown that these four phytoestrogens could be promising candidates for further evaluation for prostate cancer treatment or management.

miRNAs and androgen deprivation therapy for prostate cancer

Androgen deprivation therapy (ADT) is mainly used for the treatment of advanced, metastatic or recurrent prostate cancer (PCa). However, patients progress to ADT resistance and castration-resistant prostate cancer (CRPC) with a poor prognosis. Reliable validated markers of ADT resistance with proven clinical utility are necessary for timely correction of the therapy as well as for improvement of patient quality of life. MiRNAs involved in the ADT response and CRPC development via multiple mechanisms may act as biomarkers for patient outcomes. Available data on miRNAs associated with the ADT response (resistance and sensitivity) are summarized and analyzed in the manuscript, including analyses using bioinformatics resources. Molecular targets of miRNAs, as well as reciprocal relations between miRNAs and their targets, were studied using different databases. Special attention was dedicated to the mechanisms of ADT resistance and CRPC development, including testosterone, PI3K-AKT, VEGF pathways and associated genes. Several different approaches can be used to search for miRNAs associated with the ADT response, each of which focuses on the associated set of miRNAs - potential markers of ADT. The intersection of these approaches and combined analysis allowed us to select the most promising miRNA markers of the ADT response. Meta-analysis of the current data indicated that the selected 5 miRNAs (miRNAs - 125b, miR-21, miR-23b, miR-27b and miR-221) and 14 genes are involved in the regulation of key processes of CRPC development and represent the most promising predictors of the ADT response, further demonstrating their potential in combination therapy for advanced PCa.

Bioelectrochemical systems for environmental remediation of estrogens: A review and way forward

Globally estrogenic pollutants are a cause of concern in wastewaters and water bodies because of their high endocrine disrupting activity leading to extremely negative impacts on humans and other organisms even at very low environmental concentrations. Bioremediation of estrogens has been studied extensively and one technology that has emerged with its promising capabilities is Bioelectrochemical Systems (BESs). Several studies in the past have investigated BESs applications for treatment of wastewaters containing toxic recalcitrant pollutants with a primary focus on improvement of performance of these systems for their deployment in real field applications. But the information is scattered and further the improvements are difficult to achieve for standalone BESs. This review critically examines the various existing treatment technologies for the effective estrogen degradation. The major focus of this paper is on the technological advancements for scaling up of these BESs for the real field applications along with their integration with the existing and conventional wastewater treatment systems. A detailed discussion on few selected microbial species having the unusual properties of heterotrophic nitrification and extraordinary stress response ability to toxic compounds and their degradation has been highlighted. Based on the in-depth study and analysis of BESs, microbes and possible benefits of various treatment methods for estrogen removal, we have proposed a sustainable Hybrid BES-centered treatment system for this purpose as a choice for wastewater treatment. We have also identified three pipeline tasks that reflect the vital parts of the life cycle of drugs and integrated treatment unit, as a way forward to foster bioeconomy along with an approach for sustainable wastewater treatment.