Targeting Mitochondrial Cholesterol Efflux via TCF21/ABCA10 Pathway to Enhance Cisplatin Efficacy in Ovarian Cancer.

Abstract

Cisplatin (DDP) resistance is one of the causes of treatment failure for ovarian cancer (OV). Mitochondrial cholesterol level was reported to be associated with OV chemoresistance. We found that ABCA10, a potential cholesterol transport protein, was highly expressed in ovarian tissues and downregulated in OV tissues. Our study aimed to explore TCF21/ABCA10 axis resistance to DDP therapy in ovarian cancer based on regulating mitochondrial cholesterol efflux. Thirty epithelial ovarian cancer tumors and thirty ovarian tissues from non-cancer patients were collected. Western blot and RT-qPCR were used to measure ABCA10 and TCF21 expression levels in these tissues, as well as in a human ovarian epithelial cell line (IOSE-80), OV cells (A2780 and SKOV3), and DDP-resistant OV cell lines (A2780/DDP and SKOV3/DDP). IOSE-80 cells were also infected with ABCA10 knockdown lentivirus to identify the most effective ABCA10 knockdown plasmid. Lentiviral infection was used to create ABCA10 knockdown, ABCA10 overexpression, and TCF21 overexpression anti-DDP OV cell lines. Cell proliferation was detected by CCK-8 and EDU staining, flow cytometry for apoptosis, MTT for metabolic activity, calcium-induced Cytochrome C release, and mitochondrial matrix swelling for mitochondrial function and Oil Red O staining for lipid accumulation. Cholesterol metabolism was evaluated by measuring mitochondrial cholesterol and cholesterol efflux. Protein concentration was determined using the BCA method. A dual-luciferase reporter assay confirmed TCF21's interaction with ABCA10. ChIP also verified this interaction. The mRNA level (P < 0.01) and protein level (P < 0.001) of ABCA10 were downregulated in cancer tissues of OV patients relative to normal ovarian tissues. Relative to human ovarian epithelial cells, ABCA10 expression was significantly downregulated in OV cells (P < 0.01) and even more significantly downregulated in DDP-resistant OV cells (P < 0.001). Compared to the group treated solely with DDP, the overexpression of ABCA10 significantly inhibited the proliferation of DDP-resistant OV cells (P < 0.01), markedly reduced the staining intensity of EDU in these cells (P < 0.05), and substantially accelerated apoptosis in DDP-resistant OV cells (P < 0.01).Overexpression of ABCA10 further accelerated Cytochrome C expression and mitochondrial matrix swelling in DDP-resistant OV cells compared to the DDP-alone group (P < 0.01). The addition of cholesterol reversed the decrease in lipid accumulation, the decrease in mitochondrial cholesterol levels (P < 0.05), and the increase in cholesterol efflux (P < 0.01) in DDP-resistant OV cells caused by overexpression of ABCA10. The transcription factor TCF21 was bound to the promoter of ABCA10. Overexpression of TCF21 significantly increased ABCA10 expression in DDP-resistant OV cells (P < 0.01) and increased cytochrome C expression in A2780/DDP (P < 0.05) and SKOV3/DDP (P < 0.01) cells, with accelerated mitochondrial matrix swelling in A2780/DDP (P < 0.01) and SKOV3/DDP (P < 0.001) cells, while knockdown of ABCA10 reversed these effects. Our study found that TCF21 boosts ABCA10 expression, which in turn reduces DDP resistance in OV cells by enhancing mitochondrial cholesterol efflux. This mechanism increases the sensitivity of DDP-resistant OV cells to DDP. Our findings will provide new therapeutic targets for the treatment of ovarian cancer.