Androgen receptor negatively regulates mitotic checkpoint signaling to induce docetaxel resistance in castration‐resistant prostate cancer

Abstract

Background Despite multiple treatment advances for castration‐resistant prostate cancer (CRPC), there are currently no curative therapies and patients ultimately to succumb to the disease. Docetaxel (DTX) is the standard first‐line chemotherapy for patients with metastatic CRPC; however, drug resistance is inevitable and often develops rapidly, leading to disease progression in nearly all patients. In contrast, when DTX is deployed with androgen deprivation therapy in castration‐sensitive disease, more durable responses and improved outcomes are observed, suggesting that aberrant androgen receptor (AR) signaling accelerates DTX resistance in CRPC. In this study, we demonstrate that AR dysregulates the mitotic checkpoint, a critical pathway involved in the anticancer action of DTX. Methods Androgen‐dependent and independent cell lines were used to evaluate the role of AR in DTX resistance. Impact of drug treatment on cell viability, survival, and cell‐cycle distribution were determined by plate‐based viability assay, clonogenic assay, and cell‐cycle analysis by flow cytometry, respectively. Mitotic checkpoint kinase signal transduction and apoptosis activation was evaluated by Western blotting. Pathway gene expression analysis was evaluated by RT‐PCR. A Bliss independence model was used to calculate synergy scores for drug combination studies. Results Activation of AR in hormone‐sensitive cells induces a rescue phenotype by increasing cell viability and survival and attenuating G2/M arrest in response to DTX. Analysis of mitotic checkpoint signaling shows that AR negatively regulates spindle checkpoint signaling, resulting in premature mitotic progression and evasion of apoptosis. This phenotype is characteristic of mitotic slippage and is also observed in CRPC cell lines where we demonstrate involvement of AR splice variant AR‐v7 in dysregulation of checkpoint signaling. Our findings suggest that DTX resistance is mediated through mechanisms that drive premature mitotic exit. Using pharmacologic inhibitors of anaphase‐promoting complex/cyclosome and polo‐like kinase 1, we show that blocking mitotic exit induces mitotic arrest, apoptosis, and synergistically inhibits cell survival in combination with DTX. Conclusion Our results suggest that targeting the mechanisms of dysregulated mitotic checkpoint signaling in AR‐reactivated tumors has significant clinical potential to extend treatment benefit with DTX and improve outcomes in patients with lethal prostate cancer.

Systematic pan-cancer analysis on the expression and role of regulator of chromatin condensation 1/small nucleolar RNA host gene 3/small nucleolar RNA host gene 12

“…In Philling et al study, activation of AR increased cell viability and survival and attenuated G2/M arrest. AR negatively regulated spindle checkpoint signaling, leading to premature mitotic progression and apoptotic cell death evasion ( Pilling et al, 2022 ). Estrogen receptors (ER) belong to protein molecules, including nuclear and membranous receptors ( Eyster, 2016 ).…”

Systematic Pan-cancer Analysis on the Expression and Role of RCC1/SNHG3/SNHG12

“…In Philling et al study, activation of AR increased cell viability and survival and attenuated G2/M arrest. AR negatively regulated spindle checkpoint signaling, leading to premature mitotic progression and apoptotic cell death evasion [55]. Estrogen receptors (ER) belong to protein molecules, including nuclear and membranous receptors [56].…”

Development of a dual targeting scaffold of SET7/MLL inhibitor for castration-resistant prostate cancer treatment

“…S7 ), which is consistent with the G2/M arrest effect of MDV3100 and AR inhibitor in previous reports. 4 …”