scholarly journals Bardoxolone-Methyl (CDDO-Me) Suppresses Androgen Receptor and Its Splice-Variant AR-V7 and Enhances Efficacy of Enzalutamide in Prostate Cancer Cells

Antioxidants ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 68 ◽  
Author(s):  
Namrata Khurana ◽  
Partha K. Chandra ◽  
Hogyoung Kim ◽  
Asim B. Abdel-Mageed ◽  
Debasis Mondal ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Androgen Receptor ◽  
Splice Variants ◽  
Suppressive Effect ◽  
Castration Resistant Prostate Cancer ◽  
Protein Levels ◽  
Castration Resistant ◽  
Androgen Resistance ◽  
Anti Oxidant

Androgen receptor (AR) signaling is fundamental to prostate cancer (PC) progression, and hence, androgen deprivation therapy (ADT) remains a mainstay of treatment. However, augmented AR signaling via both full length AR (AR-FL) and constitutively active AR splice variants, especially AR-V7, is associated with the recurrence of castration resistant prostate cancer (CRPC). Oxidative stress also plays a crucial role in anti-androgen resistance and CRPC outgrowth. We examined whether a triterpenoid antioxidant drug, Bardoxolone-methyl, known as CDDO-Me or RTA 402, can decrease AR-FL and AR-V7 expression in PC cells. Nanomolar (nM) concentrations of CDDO-Me rapidly downregulated AR-FL in LNCaP and C4-2B cells, and both AR-FL and AR-V7 in CWR22Rv1 (22Rv1) cells. The AR-suppressive effect of CDDO-Me was evident at both the mRNA and protein levels. Mechanistically, acute exposure (2 h) to CDDO-Me increased and long-term exposure (24 h) decreased reactive oxygen species (ROS) levels in cells. This was concomitant with an increase in the anti-oxidant transcription factor, Nrf2. The anti-oxidant N-acetyl cysteine (NAC) could overcome this AR-suppressive effect of CDDO-Me. Co-exposure of PC cells to CDDO-Me enhanced the efficacy of a clinically approved anti-androgen, enzalutamide (ENZ), as evident by decreased cell-viability along with migration and colony forming ability of PC cells. Thus, CDDO-Me which is in several late-stage clinical trials, may be used as an adjunct to ADT in PC patients.

scholarly journals Development of an Androgen Receptor Inhibitor Targeting the N-Terminal Domain of Androgen Receptor for Treatment of Castration Resistant Prostate Cancer

Cancers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 3488
Author(s):  
Fuqiang Ban ◽  
Eric Leblanc ◽  
Ayse Derya Cavga ◽  
Chia-Chi Flora Huang ◽  
Mark R. Flory ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Androgen Receptor ◽  
Splice Variants ◽  
Full Length ◽  
Cancer Resistance ◽  
Castration Resistant Prostate Cancer ◽  
Terminal Domain ◽  
Castration Resistant ◽  
Coregulatory Proteins ◽  
Androgen Binding

Prostate cancer patients undergoing androgen deprivation therapy almost invariably develop castration-resistant prostate cancer. Resistance can occur when mutations in the androgen receptor (AR) render anti-androgen drugs ineffective or through the expression of constitutively active splice variants lacking the androgen binding domain entirely (e.g., ARV7). In this study, we are reporting the discovery of a novel AR-NTD covalent inhibitor 1-chloro-3-[(5-([(2S)-3-chloro-2-hydroxypropyl]amino)naphthalen-1-yl)amino]propan-2-ol (VPC-220010) targeting the AR-N-terminal Domain (AR-NTD). VPC-220010 inhibits AR-mediated transcription of full length and truncated variant ARV7, downregulates AR response genes, and selectively reduces the growth of both full-length AR- and truncated AR-dependent prostate cancer cell lines. We show that VPC-220010 disrupts interactions between AR and known coactivators and coregulatory proteins, such as CHD4, FOXA1, ZMIZ1, and several SWI/SNF complex proteins. Taken together, our data suggest that VPC-220010 is a promising small molecule that can be further optimized into effective AR-NTD inhibitor for the treatment of CRPC.

scholarly journals Data of relative mRNA and protein abundances of androgen receptor splice variants in castration-resistant prostate cancer

Data in Brief ◽  
2021 ◽  
Vol 34 ◽  
pp. 106774
Author(s):  
Tianfang Ma ◽  
Nathan Ungerleider ◽  
Derek Y. Zhang ◽  
Eva Corey ◽  
Erik K. Flemington ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Androgen Receptor ◽  
Splice Variants ◽  
Castration Resistant Prostate Cancer ◽  
Castration Resistant ◽  
Androgen Receptor Splice Variants

scholarly journals Isoform specific activities of androgen receptor and its splice variants in prostate cancer cells

Endocrinology ◽  
2020 ◽  
Author(s):  
Harika Nagandla ◽  
Matthew J Robertson ◽  
Vasanta Putluri ◽  
Nagireddy Putluri ◽  
Cristian Coarfa ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Androgen Receptor ◽  
Target Gene ◽  
Target Genes ◽  
Splice Variants ◽  
Clinical Samples ◽  
Castration Resistant Prostate Cancer ◽  
Castration Resistant ◽  
Specific Activities ◽  
Lncap Prostate Cancer Cell

Abstract Androgen receptor (AR) signaling continues to drive castration resistant prostate cancer (CRPC) in spite of androgen deprivation therapy (ADT). Constitutively active shorter variants of AR, lacking the ligand binding domain, are frequently expressed in CRPC and have emerged as a potential mechanism for prostate cancer to escape ADT. ARv7 and AR v567es are two of the most commonly detected variants of AR in clinical samples of advanced, metastatic prostate cancer. It is not clear if variants of AR merely act as weaker substitutes for AR or can mediate unique isoform specific activities different from AR. In this study, we employed LNCaP prostate cancer cell lines with inducible expression of ARv7 or AR v567es to delineate similarities and differences in transcriptomics, metabolomics and lipidomics resulting from the activation of AR, ARv7 or AR v567es. While the majority of target genes were similarly regulated by the action of all three isoforms, we found a clear difference in transcriptomic activities of AR versus the variants, and a few differences between ARv7 and AR v567es. Some of the target gene regulation by AR isoforms was similar in the VCaP background as well. Differences in downstream activities of AR isoforms were also evident from comparison of the metabolome and lipidome in an LNCaP model. Overall our study implies that shorter variants of AR are capable of mediating unique downstream activities different from AR and some of these are isoform specific.

MicroRNA Regulation of Androgen Receptor in Castration-Resistant Prostate Cancer: Premises, Promises, and Potentials

2020 ◽  
Vol 13 ◽  
Author(s):  
Safieh Ebrahimi ◽  
Seyed Isaac Hashemy ◽  
Amirhossein Sahebkar ◽  
Seyed Hamid AghaeeBakhtiari
Keyword(s):  
Prostate Cancer ◽  
Androgen Receptor ◽  
Signaling Pathways ◽  
Therapeutic Potential ◽  
Splice Variants ◽  
Castration Resistant Prostate Cancer ◽  
Castration Resistance ◽  
Contributing Factors ◽  
Development Of Resistance ◽  
Castration Resistant

: Prostate cancer (PCa) is the second most prevalent cancer and the fifth leading cause of cancer-related deaths among men. Androgen deprivation therapy (ADT) is the most frequently used therapeutic strategy in PCa; however, the development of resistance to ADT, known as castration-resistant prostate cancer (CRPC), continues to be a major obstacle against successful treatment of PCa. The abnormal activation of the androgen receptor (AR) signaling pathway has been found as one of the main contributing factors to the development of resistance in CRPC. Therefore, AR regulatory strategies are urgently required to combat resistance. Recently, microRNAs (miRNAs) have been found as major AR regulatory factors affecting ADT resistance. MiRNAs can target AR itself, AR-related genes, AR splice variants, ARrelated signaling pathways as well as cancer stem cells (CSCs), and play critical roles in regulating ADT resistance. Due to their capability to affect various genes and signaling pathways, miRNAs are now being studied for their potential role as a new therapeutic target in CRPC. It has been recommended that combination therapies including miRNAs and existing drugs can synergistically decrease castration resistance. miRNAs have also prognostic values for ADT, and their expression profiling in CRPC patients before therapeutic scheduling may enable the physician to diagnose patients who are ADT-resistant. Overall, extant evidence obviously supports the predictive and therapeutic potential of miRNAs in CRPC patients. This review summarizes the available information about the microRNA-mediated AR controlling mechanisms involved in ADT resistance.

Combinatorial expression of androgen receptor splice variants: No predictive value in castration-resistant prostate cancer patients treated with enzalutamide (enza) or abiraterone (abi).

2020 ◽  
Vol 38 (15_suppl) ◽  
pp. e17547-e17547
Author(s):  
Katrin Schlack ◽  
Konstantin Seitzer ◽  
Martin Boegemann ◽  
Laura-Maria Krabbe ◽  
Andres Jan Schrader ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Androgen Receptor ◽  
Splice Variant ◽  
Predictive Power ◽  
Splice Variants ◽  
Statistical Significance ◽  
Therapy Response ◽  
Hormonal Treatment ◽  
Castration Resistant Prostate Cancer ◽  
Castration Resistant

e17547 Background: Playing an important role in prostate cancer, androgen receptor (AR) signaling is a common therapeutic target. Novel hormonal treatment (NHT) using enza or abi prolongs overall survival in men with metastatic castration-resistant prostate cancer (mCRPC). However, biomarkers predicting therapy response are limited. AR-V7, as the most abundant AR splice variant, has gained clinical interest. Nonetheless, current discussions on its predictive power are diverse. Given that AR-V7 as a sole biomarker is not efficient in predicting response to NHT, we aimed to increase the predictive potential by analysis of combinatorial AR splice variant (AR-V) expression in mCRPC patients undergoing NHT. Methods: We prospectively enrolled 60 patients who started on either abi or enza. Presence of circulating tumor cells (CTC) as well as expression of AR-V3, -7 and -9 were assessed. Outcomes in CTC-, CTC+/AR-V- and CTC+/AR-V+ patients were analyzed considering PSA reduction, PSA-PFS, PFS and OS. Results: PSA reduction of 50% was predominantly found in CTC- patients (78.5%) compared to CTC+/AR-V- (55.5%) and CTC+/AR-V+ (39.3%) without statistical significance (P = 0.059). When taking co-expression of two or more AR-V into account there was no difference in PSA response either (one AR-V 42.9%, two AR-V 33.3%, three AR-V 41.6%, P = 0.154). Median PSA-PFS was 17 months (95%CI 15.7 – 18.3), 13 months (95%CI 6.8 – 19.2) and 5 months (95%CI 3.6 – 6.4) for CTC- pts, CTC+/AR-V- pts and CTC+/AR-V+ pts, respectively (P = 0.005). However, comparing CTC- and CTC+ pts, differences become even more apparent (P = 0.004), CTC+/AR-V- and AR-V+ pts showed less statistically significant differences (P = 0.029). Median PFS and OS were not reached for CTC- pts. PFS was 10 months (95%CI 6.2 – 13.8) for CTC+/AR-V- pts and 9 months (95%CI 1.1 – 16.9) for CTC+/AR-V+ pts (P = 0.004, only CTC- vs. CTC+ P = 0.002). OS was 28 months (95%CI 16.8 – 39.2) for CTC+/AR-V- pts and 15 months (95%CI 7.9 – 22.1) for CTC+/AR-V+ pts (P = 0.014, only CTC- vs. CTC+ P = 0.006). Regarding PFS and OS, there was no difference comparing only CTC+/AR-V- and AR-V+ pts (P = 0.356 and P = 0.244). Conclusions: AR splice variants have prognostic power in stratifying mCRPC patients suffering from a more advanced stage of disease. Nonetheless, our study clearly demonstrates the lack of predictive power of AR splice variants for response to NHT. Additionally, we prove the importance of CTC analysis rather than AR-V expression being more valuable in mCRPC.

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