Abstract: Objective To investigate the role and underlying mechanism of glucose-6-phosphate dehydrogenase (G6PD) in cisplatin resistance of ovarian cancer cells. Methods The cisplatin-resistant ovarian cancer cell line A2780/CDDP was established by continuous induction with low concentration. The differential expressed protein G6PD in A2780 and A2780/CDDP cells were analyzed by a Label-free protein quantification method. The expression levels of G6PD was detected by Western blot and RT-qPCR. siRNA-G6PD and its negative control (siRNA-NC) were transfected into A2780/CDDP cells by siRNA technique and then the effect of G6PD gene silencing was verified by Western blot. MTT experiment was used to detect cell proliferation ability and flow cytometry was used to detect the apoptosis rate. The expression levels of reactive oxygen species (ROS), malondialdehyde (MDA), reduced glutathione (GSH) and lipid peroxides related to ferroptosis were detected by flow cytometry and microplate reader. Results Compared with A2780 cells, there were 95 up-regulated proteins and 102 down-regulated proteins in A2780/CDDP cells, among which G6PD had the most significant difference in expression. Most of these proteins were enriched in metabolic pathways, and their functions were mainly related to cellular oxidative stress response and ribose phosphoric acid metabolism pathways. Compared with A2780 cells, the expression levels of G6PD mRNA and protein in A2780/CDDP cells were significantly increased (all P<0.05), the levels of ROS, MDA and the lipid peroxides related to ferroptosis were decreased (all P<0.05), while the GSH level was increased (P=0.001). After silencing G6PD, the IC₅₀ value of cisplatin in A2780/CDDP cells was decreased ( P=0.012), the apoptosis rate was increased (P=0.006), and the levels of ROS, MDA and the lipid peroxides related to ferroptosis were increased (all P<0.05), while the GSH level was decreased (P=0.007). Conclusions Silencing G6PD may enhance cisplatin sensitivity by inducing the ferroptosis levels in cisplatin-resistant ovarian cancer cells A2780/CDDP.

Key words: Ovarian cancer, Cisplatin resistance, Proteomics, Glucose-6-phosphate dehydrogenase, Apoptosis, Ferroptosis