Abstract 5508: Artesunate increases enzalutamide efficacy in advanced prostate cancer

Abstract

Prostate cancer (PCa) is the most diagnosed worldwide. PCa development and progression require androgen receptor (AR) signaling, which stimulates its downstream gene expressions and cancer progression. While second-generation anti-androgen drugs plus androgen deprivation therapy (ADT) remains the first-line treatment for advanced prostate cancer patients, around one-third of patients will relapse in a short period. Advanced prostate cancer results in more mortalities than primary PCa patients. Evidence shows that the recurrence is caused by AR overexpression, AR variants, AR mutations, and signaling crosstalk. Thus, it is urgently needed to discover a novel therapeutic strategy for treating advanced prostate cancer. The heat shock protein family (HSP), including HSP90 and HSP70, play important roles in refolding aggregated protein for cancer cell proteomic equilibrium. HSP is induced primarily by heat shock factor (HSF1). As AR’s chaperone protein, HSP70 and HSP90 increase AR transcription activity. Inhibiting HSP70 and HSP90 promotes STUB1, an E3 ligase, binding to AR and AR - V7, and ubiquitination. Artesunate (ART) is a semi-synthetic ingredient from Artemisia annua and is the most common treatment for malaria throughout the world. It was approved for medical use by the FDA (Food and Drug Administration) (Food and Drug Administration). Recently ART has been unveiled for its anticancer properties. However, the efficacy of ART treatment in advanced prostate cancer and the direct target of ART have not been investigated yet. Herein, we have examined the efficacy of combining Enzalutamide (Enza) and ART in advanced prostate cancer cell lines. We also performed unbiased bioinformatics analysis using RNA seq results in enzalutamide-resistant cell line C4-2R cells and 22RV1 cells to investigate the cell response toward ART treatment. We identified ART could downregulate of AR signaling pathway. Moreover, we determined that ART treatment induces AR degradation in proteasome dependent manner. Interestingly, we found HSP70 and HSP90 are also decreased in RNA seq results. Taking these together suggests that ART may target HSF1 directly. Our results suggest ART induced AR degradation could be a promising clinical strategy for advanced prostate cancer. Citation Format: Xinyi Wang, Fengyi Mao, Jinghui Liu, Yifan Kong, Dang he, Chi Wang, Zhiguo Li, Xiaoqi Liu. Artesunate increases enzalutamide efficacy in advanced prostate cancer. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5508.