HIF-1α-mediated regulation of ATG7 and KDM5C in ferroptosis.

Abstract

Hypoxia, a hallmark of the solid tumor microenvironment (TME), drives malignant progression and confers therapy resistance. In liver cancer, the hypoxia-inducible factor-1α (HIF-1α) has been implicated in suppressing ferroptosis, a key mechanism of therapy resistance; however, its precise regulatory network remains elusive. To systematically identify novel mediators within the HIF-1α-ferroptosis axis, we integrated bioinformatic analyses of The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) datasets with experimental validation in hypoxic cells. This strategy identified ATG7 and KDM5C as core hypoxia-responsive genes. ATG7, a key autophagy regulator, also maintains iron homeostasis and modulates oxidative stress, while the histone demethylase KDM5C regulates metabolic and antioxidant gene expression. To functionally dissect their roles, we engineered a novel dual-fluorescence reporter system in HepG2 cells. This system utilizes a synthetic HIF-1α responsive promoter, comprising five tandem repeats of the hypoxia response element (HRE), to drive EGFP expression, thereby reporting hypoxic signaling. Concurrently, the activity of the ATG7 or KDM5C promoter is reported by miRFP670. The resulting cell lines (HepG2-ATG7p-miRFP670-5HRE-EGFP and HepG2-KDM5Cp-miRFP670-5HRE-EGFP) thus visually couple promoter activity with the HIF-1α-mediated hypoxic response. Our work provides a powerful visualizable platform to dynamically study the crosstalk between HIF-1α and ferroptosis in liver cancer, facilitating the exploration of hypoxia-ferroptosis interplay in hepatocarcinogenesis and therapeutic response.