MBD3 Regulates The Role Of HIF2? In Tumor Cells Through Demethylation And Transcription

Hypoxia inducible factor 2a(HIF2a)plays critical roles in cancer progression.Although the mechanisms of HIF2a translation and degradation have been well studied,the mechanism of HIF2a regulation at transcriptional level is still not fully understood.Here we present evidence that DNA methylation in promoter contributes to the transcription of EPAS1 coding HIF2a.Methylated CpG binding protein 3(MBD3)is usually involved in DNA methylation,which occurs at CpG harbored in promoter of DNA,and then contributes to the intricate regulatory mechanism.In this study,we detected much rich methylated CpG located in the promoter of EPAS1 in MDA-MB-468 breast cancer cells.We showed that MBD3 bound to the EPAS1 promoter in MDA-MB-468 breast cancer cells,and amplified EPAS1 transcription through demethylating CpG located around tanscriptional start site.This enables cancer cells to activate HIF2a mediated cell angiogenesis.However,in 7860 renal cells,because of the poor methylated-CpG promoter existence,the demethylation function of MBD3 on EPAS1 was not observed.However,depletion of MBD3 induced by shRNA plasmid transfection decreased EPAS1 transcription and therefore decreased HIF2a-mediated cellular response in both MDA-MB-468 and 7860 cancer cells.These results suggested that the endogenous MBD3 was involved in regulating EPAS1 transcription and therefore the transcriptional activities of HIF2a.Our study suggests that MBD3 may be a potential therapeutic target of tumor.