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Docetaxel has been the standard first-line chemotherapy for lethal metastatic prostate cancer (mPCa) since 2004, but the resistance to docetaxel treatment is common. The molecular mechanisms of docetaxel resistance remain largely unknown and could be amenable to interventions that mitigate resistance. We have recently discovered that several docetaxel resistant mPCa cell lines exhibit less uptake of cellular copper and express markedly higher levels of ATP7B protein without significant changes in the protein expression levels of other copper transporters, such as ATPase copper transporting alpha (ATP7A) and high affinity copper uptake protein 1 (CTR1). Knock-down of ATP7B by silencing RNAs sensitized docetaxel resistant-mPCa cells to the growth inhibitory and apoptotic effects of docetaxel. Importantly, deletions of ATP7B in mPCa tissues predict significantly better survival of patients after their first chemotherapy than those with wild-type ATP7B (P = 0.0006). In addition, Disulfiram (DSF), an FDA approved drug for treatment of alcohol dependence, in combination with copper, significantly enhanced the in vivo antitumor effects of docetaxel in a docetaxel resistant xenograft tumor model. Our analyses also revealed that DSF and copper engaged with ATP7B to decrease protein levels of COMM domain-containing protein 1 (COMMD1), S-phase kinase associated protein 2 (Skp2) and clusterin and markedly increase protein expression of cyclin-dependent kinase inhibitor 1 (p21/WAF1). Taken together, our results suggest that ATP7B is a clinically relevant and key target for improving the efficacy of docetaxel for treatment of mPCa. Citation Format: Liankun Song, Vyvyan Nguyen, Jun Xie, Matthew Tippin, Le TP Truong, Christopher A. Blair, Beverly Wang, Edward Uchio, Xiaolin Zi. ATPase copper transporting beta (ATP7B) contributes to acquired docetaxel resistance in human 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 1687. |
