Modulation of intracellular heme metabolism enhances artesunate-induced cytotoxicity in CD44v-positive cervical cancer cells.

In this study, we investigated the role of intracellular heme metabolism in regulating artesunate (ATS)-induced cytotoxicity to overcome therapeutic resistance in refractory cervical cancer. CD44v-positive CaSki cells exhibited resistance to both cisplatin and the ferroptosis inducer erastin, associated with elevated antioxidant capacity and impaired iron mobilization. Although ATS cytotoxicity was enhanced by exogenous heme, stimulation of endogenous heme biosynthesis with 5-aminolevulinic acid (ALA) increased intracellular heme levels and lipid peroxidation but failed to significantly enhance cell death. Targeting canonical antioxidant pathways, including reduction of glutathione (GSH) availability and inhibition of nuclear factor erythroid 2-related factor 2 (NRF2) or glutathione peroxidase 4 (GPX4), produced variable but incomplete sensitization to ATS in CaSki cells. In contrast, simultaneous stimulation of heme biosynthesis with ALA and inhibition of heme degradation with zinc protoporphyrin IX markedly increased intracellular labile heme levels and produced the strongest sensitization to ATS among the treatment conditions examined in CaSki cells. These findings support a role for intracellular heme availability in modulating the heme-dependent bioactivation and cytotoxic efficacy of ATS and suggest that the extent of labile heme accumulation may influence ATS responsiveness in CaSki cells. Collectively, our results suggest that coordinated modulation of heme biosynthesis and degradation can enhance ATS cytotoxicity and may provide a strategy for sensitizing therapy-resistant cervical cancer cells to ATS.