Zerumbone enhances TRAIL-induced apoptosis via USP9x-mediated downregulation of Mcl-1

Zerumbone (ZER), a sesquiterpenoid compound extracted from Zingiber zerumbet Smith, exhibits notable anti-proliferative and anti-inflammatory activities. TRAIL (tumor necrosis factor-related apoptosis-inducing ligand) selectively induces apoptosis in tumor cells with minimal impact on normal cells, positioning it as a promising anticancer agent. However, TRAIL resistance remains a major barrier to its clinical effectiveness. In this study, we investigated the synergistic effects of co-treatment with ZER and TRAIL in cancer cells. Our results demonstrated that combined treatment with ZER and TRAIL markedly enhances apoptosis in renal carcinoma cells. ZER treatment induced a decrease in the expression of anti-apoptotic protein Mcl-1, which affected TRAIL-mediated cell death. However, Mcl-1 overexpression attenuated combined treatment-mediated cell death. Furthermore, ZER downregulated the deubiquitinating enzyme USP9x expression level, which plays a key role in Mcl-1 stabilization. Also, overexpression of USP9x prevented combined treatment-induced apoptosis. These findings suggest that ZER increases TRAIL-induced apoptosis by modulating the USP9x-Mcl-1 axis and ZER may serve as a potential strategy to overcome TRAIL resistance in cancer therapy.