Abstract 2446: Low dose dimethyl sulfoxide (DMSO) downregulates the expression of androgen receptor (AR) and AR-variant 7 (AR-v7) in castration resistant prostate cancer (CRPC) cells

Abstract The highly aggressive prostate cancer (PC) cells utilize androgen receptor (AR) signaling to facilitate their growth and metastasis. Despite androgen deprivation therapy (ADT), recurrence of castration-resistant prostate cancer (CRPC) often occur due to constitutive AR signaling via both full-length AR (AR-FL) and AR splice variants, primarily AR-V7. Therefore, safe strategies to suppress both AR-FL & AR-V7 expression in CRPC cells will be of significant benefit. Several plant-derived organosulfur compounds, e.g. sulforaphane and diallyl-trisulfide, can potently suppress AR expression in CRPC cells, but are yet to be clinically approved. We investigated whether dimethyl sulfoxide (DMSO) an approved organosulfur compound often used as a solvent for pharmaceutical agents, can similarly suppress AR levels in the CRPC cell lines, C4-2B and 22Rv1. Exposure to low dose DMSO (0.1-1%) was not cytotoxic to these CRPC cells, and less than 20% cytotoxicity was seen with 2.5% DMSO even at 96 h post-exposure. Interestingly however, DMSO dose-dependently suppressed AR-FL in C4-2B cells and both AR-FL and AR-V7 in 22Rv1 cells within 24 h post-exposure. Exposure to DMSO also downregulated the expression of hetero-nuclear ribonucleoprotein H1 (hnRNPH1), which is known to regulate AR expression and splicing. Although DMSO exposure showed a dose- and time-dependent effect on reactive oxygen species (ROS) production by PC cells, the AR-suppressive effect of DMSO was not altered by the antioxidant n-acetyl cysteine (NAC). Furthermore, although DMSO did not affect cell viability at these clinically-achievable concentrations, a significant (p<0.01) decrease in the migratory ability of both CRPC cell lines was clearly evident. Our novel findings indicate that safe doses of DMSO may be used to decrease AR expression and metastatic ability in CRPC cells. Citation Format: Namrata Khurana, Hogyoung Kim, Talal Khan, Shohreh Kahhal, Amar Bukvic, Asim B. Abdel-Mageed, Suresh C. Sikka, Debasis Mondal. Low dose dimethyl sulfoxide (DMSO) downregulates the expression of androgen receptor (AR) and AR-variant 7 (AR-v7) in castration resistant prostate cancer (CRPC) cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2446.