Hypoxia Enhances HIF1α Transcription Activity by Upregulating KDM4A and Mediating H3K9me3, Thus Inducing Ferroptosis Resistance in Cervical Cancer Cells

Abstract

Objective. Cervical cancer (CC) is a prevalent cancer in women. Hypoxia plays a critical role in CC cell ferroptosis resistance. This study explored the mechanism of hypoxia in CC cell ferroptosis resistance by regulating HIF1α/KDM4A/H3K9me3. Methods. Cultured SiHa and Hela cells were exposed to CoCl2 and treated with Erastin. Cell viability was detected by MTT assay, and concentrations of iron ion, MDA and GSH were determined using corresponding kits. Expressions of KDM4A, HIF1α, TfR1, DMT1, and H3k9me3 were detected by RT-qPCR, Western blot, and ChIP assay. The correlation of KDM4A and HIF1α was analyzed on Oncomine, UALCAN, and Starbase. CC cells were co-transfected with shKDM4A or/and pcDNA3.1-HIF1α. Iron uptake and release were assessed using the isotopic tracer method. The binding relationship between HIF1α and HRE sequence was verified by dual-luciferase assay. Results. Cell viability and GSH were decreased while iron concentration, MDA, KDM4A, and HIF1α levels were increased in hypoxia conditions. The 2-h hypoxia induced ferroptosis resistance. KDM4A and HIF1α were highly-expressed in CC tissues and positively correlated with each other. KDM4A knockdown attenuated cell resistance to Erastin, increased H3K9me3 level in the HIF1α promoter region, and downregulated HIF1α transcription and translation. H3K9me3 level was increased in the HIF1α promoter after hypoxia. HIF1α overexpression abrogated the function of KDM4A knockdown on ferroptosis in hypoxia conditions. Iron uptake/release and TfR1/DMT1 levels were increased after hypoxia. Hypoxia activated HRE sequence in TfR1 and DMT1 promoters. Conclusion. Hypoxia upregulated KDM4A, enhanced HIF1α transcription, and activated HRE sequence in TfR1 and DMT1 promoters via H3K9me3, thus inducing ferroptosis resistance in CC cells.

Cantharidin Inhibits Proliferation of Liver Cancer by Inducing DNA Damage via KDM4A-Dependent Histone H3K36 Demethylation

“…Studies have found that KDM4A is involved in the regulation of cell proliferation, differentiation, development, metabolism, and other important biological processes [ 10 , 11 ]. Its abnormal function is also closely related to the occurrence and development of tumors and other diseases, becoming an important target for tumor therapy [ 12 ]. Histone methylation is one of the important epigenetic modifications, which plays an important role in many biological processes such as transcription activation and suppression, sex chromosome silencing, and DDR.…”

Ferroptosis Regulated by Hypoxia in Cells

“…Consistently, the abovementioned studies showed that HIF-2α inhibits ferroptosis through its direct targets involved in iron metabolism, such as FTMT , in both tumor and normal cells [ 102 , 112 ]. However, it is also reported that HIF-1α regulates iron metabolism directly through transcriptionally regulation of its targets, such as TFRC and DMT1 [ 120 ], as well as indirectly through some other targets, such as CA9 [ 103 ]. Fe 2+ is a cofactor for PHDs and FIH-1, which regulates HIFs under normoxia.…”

“…Another report showed that HIF-2α upregulated genes involved in lipid and iron metabolism in both colorectal cancer (CRC) cells and colon tumors in mice, which result in the cells being susceptible to ferroptosis induced by dimethyl fumarate [ 119 ]. It was also reported that lysine (K)-specific demethylase 4A (KDM4A), which was highly expressed in cervical cancer tissue and could be induced under cobalt chloride mimicking hypoxia conditions, reduces the H3K9me3 level in the HIF-1α promoter region to elevate HIF-1α transcription, leading to the increased expression of TFRC and DMT1 via activating the HRE sequence in their promoters, and finally resulting in the increase in erastin-induced ferroptosis of cervical cancer cells [ 120 ]. In addition to HIFs, hypoxia also induced E2F transcription factor 7(E2F7) to increase the transcription of splicing factor quaking ( QKI ), which promotes the biogenesis of circBCAR3 , a circular RNA highly expressed in the esophageal cancer cells [ 121 ].…”

Integrative analysis identifies potential ferroptosis-related genes of hypoxia adaptation in yak

“…In previous studies, hypoxia can activate the PINK1/Parkin-mediated mitophagy pathway ( 19 ), selective activation of mitophagy might promote cell survival under hypoxic conditions ( 20 ), breast cancer ( 21 ), and pulmonary fibrosis ( 22 ). Tumor cells were exposed to hypoxia, the yak was in the hypoxic environment, the down-regulated DE-FRGs in the oviduct is also enriched in HIF-1 signaling pathway, HIF-1 is a central regulator of cellular adaptation to hypoxia ( 23 ), positively selected hypoxia-related genes in the buff-throated partridge were distributed in the HIF-1 signaling pathway ( 24 ), Hypoxia Enhances HIF-1α Transcription Activity by Upregulating KDM4A and Mediating H3K9me3 ( 25 ), suppression of the HIF-1 signaling pathway by microRNA regulation may play a key role in the pathogenesis of un-acclimatization with high altitude hypoxia ( 26 ), HIF-1 signaling pathway is an important topic in high-altitude medicine ( 27 ), the previous hypoxia research were consistent with this study. Therefore, HIF-1 signaling pathway may play an important role in the regulation of ferroptosis by hypoxia-induced.…”