Carboxymethylated pachyman induces ferroptosis in ovarian cancer by suppressing NRF1/HO-1 signaling

Carboxymethylated pachyman (CMP) is characterized by immune regulatory, antitumor and antioxidant activities. However, whether CMP contributes to the treatment of ovarian cancer has yet to be explored. The role of CMP in ovarian cancer cell death was analyzed using CCK-8 and flow cytometry assays. The data showed that CMP induced ovarian cancer cell death in a dose-dependent manner. Furthermore, CMP-induced cell death could be largely reversed by preincubation with ferrostatin-1 (Fer-1) but not 3-methyladenine or necrostatin-1. Reverse transcription-quantitative PCR analysis indicated that CMP significantly increased prostaglandin-endoperoxide synthase 2 (PTGS2) and Chac glutathione specific γ-glutamylcyclotransferase 1 (CHAC1) mRNA levels, but preincubation with Fer-1 obviously reduced PTGS2 and CHAC1 mRNA levels in SKOV3 and Hey cells. The intracellular levels of superoxide dismutase (SOD), glutathione (GSH), malondialdehyde (MDA) and Fe(2+) were then quantified The data showed that 100 and 200 µg/ml CMP enhanced the production of SOD, MDA and Fe(2+) but decreased GSH levels in SKOV3 and HEY cells. These data indicated that CMP could induce ferroptosis in ovarian cancer cells. More importantly, in vitro and in vivo studies indicated that CMP significantly suppressed nuclear factor erythroid 2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1), cystine/glutamate antiporter system X(c)(−) (xCT) and glutathione peroxidase 4 (GPX4) expression in ovarian cancer cells and tumors. In conclusion, the present study showed novel data that CMP could induce ferroptotic death in ovarian cancer cells by suppressing Nrf2/HO-1/xCT/GPX4. All these findings indicate that CMP may have great potential in anti-ovarian cancer cell therapy by inducing ferroptosis.