Estrogen-induced epigenetic silencing ofFTH1andTFRCgenes reduces liver cancer cell growth and survival

Estrogen (E2) regulates hundreds of genes involved in cell metabolism and disrupts iron homoeostasis in various cell types. Herein, we addressed whether E2-induced epigenetic modifications are involved in modulating the expression of iron-regulatory genes. Epigenetic status ofFTH1andTFRCgenes was assessed in E2-treated cancer cells. E2-induced DNA methylation was associated with decreasedFTH1andTFRCexpression in Hep-G2 and Huh7 cells, but not in AGS or MCF7 cells. Demethylation with 5-Aza-2-deoxycytidine upregulated the expression of both these genes in Hep-G2 cells. The expression of DNMT3B, PRMT5, and H4R3me2s increased in E2-treated cells. Chromatin immunoprecipitation showed that E2 treatment recruited PRMT5 and H4R3me2s onFTH1but not onTFRC. Knockdown of PRMT5, DNMT3B, and Estrogen-receptor alpha rescuedFTH1from E2-induced silencing. However, knockdown of DNMT3B alone blocked the inhibitory effects of E2 onTFRC. Analysis of human liver tissues in publicly available datasets showed thatFTH1andTFRCare highly expressed in primary liver tumours, but a lower expression is associated with better survival. Interestingly, we showed that the silencing ofFTH1and/orTFRCinhibited carcinogenesis in Hep-G2 cells. For the first time, our findings uncovered the novel signalling pathway involved in the protective effects of E2 against liver cancer.