KDM4A Silencing Reverses Cisplatin Resistance in Ovarian Cancer Cells by Reducing Mitophagy via SNCA Transcriptional Inactivation

Background: Ovarian cancer is one of the deadliest gynecologic cancers, with chemotherapy resistance as the greatest clinical challenge. Autophagy occurrence is associated with cisplatin (DDP)-resistant ovarian cancer cells. Herein, the role and mechanism of alpha-synuclein (SNCA), the autophagy-related gene, in DDP resistance of ovarian cancer cells are explored. Methods: Differentially expressed genes in DDP resistance of ovarian cancer cells were analyzed by GEO2R tools. DDP-resistant ovarian cancer cells (A2780/DDP) were transfected and treated with 2.5 μg/mL DDP for 72 h, followed by the determination of cell viability, proliferation, apoptosis, and expressions of SNCA, lysine demethylase 4A (KDM4A), histone H3 lysine 9 trimethylation (H3K9me3), and mitophagy-related proteins. The H3K9me3 demethylation of SNCA by KDM4A was confirmed by chromatin immunoprecipitation. Results: SNCA and KDM4A were highly expressed in DDP-resistant ovarian cancer cells and their parental cells. KDM4A knockdown diminished expressions of KDM4A and SNCA and elevated H3K9me3 expression and H3K9me3 enrichment on SNCA promoter in A2780/DDP cells. SNCA or KDM4A knockdown inhibited cell viability, proliferation, and levels of LC3-II/LC3-I and Parkin while inducing cell apoptosis and upregulating Cyt-C expression of A2780/DDP cells with/without DDP treatment; however, SNCA overexpression not only did conversely but also reversed the effects of KDM4A knockdown on DDP-treated A2780/DDP cells and vice versa. Conclusion: Silencing of KDM4A-mediated transcription inactivation of SNCA reduces mitophagy, thus inhibiting the resistance of ovarian cancer cells to cisplatin. KDM4A may be a promising drug target for DDP-resistant ovarian cancer cells.