Mitochondrial pathway of the lysine demethylase 5C inhibitor CPI-455 in the Eca-109 esophageal squamous cell carcinoma cell line

BACKGROUND: Esophageal cancer is a malignant tumor of the digestive tract that is difficult to diagnose early. CPI-455 has been reported to inhibit various cancers, but its role in esophageal squamous cell carcinoma (ESCC) is unknown. AIM: To investigate the effects and mechanism of the lysine demethylase 5C inhibitor, CPI-455, on ESCC cells. METHODS: A methyl tetrazolium assay was used to detect the inhibitory effect of CPI-455 on the proliferation of Eca-109 cells. Apoptosis, reactive oxygen species (ROS), and mitochondrial membrane potential were assessed by flow cytometry. Laser confocal scanning and transmission electron microscopy were used to observe changes in Eca-109 cell morphology. The protein expression of P53, Bax, lysine-specific demethylase 5C (KDM5C), cleaved Caspase-9, and cleaved Caspase-3 were assayed by western blotting. RESULTS: Compared with the control group, CPI-455 significantly inhibited Eca-109 cell proliferation. Gemcitabine inhibited Eca-109 cell proliferation in a concentration- and time-dependent manner. CPI-455 caused extensive alteration of the mitochondria, which appeared to have become atrophied. The cell membrane was weakly stained and the cytoplasmic structures were indistinct and disorganized, with serious cavitation when viewed by transmission electron microscopy. The flow cytometry and western blot results showed that, compared with the control group, the mitochondrial membrane potential was decreased and depolarized in Eca-109 cells treated with CPI-455. CPI-455 significantly upregulated the ROS content, P53, Bax, Caspase-9, and Caspase-3 protein expression in Eca-109 cells, whereas KDM5C expression was downregulated. CONCLUSION: CPI-455 inhibited Eca-109 cell proliferation via mitochondrial apoptosis by regulating the expression of related genes.