17 β-Estradiol inhibits GSDME-mediated pyroptosis in ERα-positive breast cancer cells by promoting GSDME promoter methylation.

Expression of the critical pyroptosis protein gasdermin E (GSDME) has been reported to be regulated by DNA methylation and negatively correlated with the expression of estrogen receptor (ER) in breast cancer tissues, suggesting that estrogen-induced target gene methylation may be involved in the regulation of GSDME expression in breast cancer cells. To test this hypothesis, we treated MCF-7 and T47D ER-positive breast cancer cells with 17-β-Estradiol (E), either alone or in combination with selective ERα antagonist AZD9496, selective ERβ antagonist PHTPP, DNA methyltransferase (DNMT) inhibitor RG108, and selective ER degrader Fulvestrant (Ful). Then, GSDME protein and mRNA expression were examined with western blot and RT-qPCR. Pyroptosis was induced by short-wave ultraviolet (UV-C) and detected with morphological observation, lactate dehydrogenase (LDH) release assay, and propidium iodide-Annexin V-FITC fluorescence staining. The methylation status of the GSDME promoter was tested with methylation-specific PCR. The results demonstrated that 100 nM E significantly decreased GSDME protein and mRNA expression in MCF-7 and T47D cells, and significantly inhibited UV-C-induced pyroptosis. AZD9496 but not PHTPP significantly attenuated the down-regulatory effect of E on GSDME expression. E induced DNA methylation in the GSDME promoter region and up-regulated DNMT1 expression. RG108 strengthened UV-C-induced pyroptosis, and Ful reversed the inhibitory effects of E on UV-C-induced pyroptosis of MCF-7 and T47D cells Taken together, our study suggests that E down-regulated GSDME expression in ERα-positive breast cancer by promoting GSDME promoter methylation, and inhibited UV-C-induced pyroptosis.