The Function And Mechanism Study Of OVOL2 In Glycolysis

Normal cells mainly rely on mitochondrial oxidative phosphorylation for energy supply.However,unlike normal cells,most cancer cells prioritize to glycolysis even under aerobic conditions.This phenomenon is called the "Warburg effect"(also called aerobic glycolysis).As a hallmark of cancer,aerobic glycolysis plays a vital role in the growth and metastasis of cancer cells,and drugs targeting aerobic glycolysis show promising anticancer activity in vivo and in vitro.Aerobic glycolysis is directly regulated by transcription factors,such as hypoxia inducible factor-1α(HIF-1α),oncogene c-Myc,homeobox 1(SIX1),Forkhead box K(FOXK)1 and FOXK2,and tumor suppressor p53.HIF-1α,c-Myc,SIX1 and FOXK1/2can directly activate the expression of glycolytic genes and promote aerobic glycolysis by binding the promoters of glycolytic-related genes.In contrast,p53,a transcription factor with tumor suppressive function,can directly inhibit the transcription of glycolytic genes by binding the promoters of glycolytic genes,thus reducing aerobic glycolysis.The transcriptional activation mechanism of Warburg effect has been extensively studied,but the molecular mechanism of direct transcriptional inhibition of Warburg effect is still largely unclear.Ovo like zinc finger 2(OVOL2)is a member of the OVO family of zinc finger conserved transcription factors.Studies have shown that OVOL2 plays an important role in spermatogenesis,epithelial cell growth and embryo development.In addition,OVOL2 can inhibit the migration,invasion and metastasis of cancer cells,and the decrease of OVOL2 expression indicates a poor clinical prognosis.However,it is unclear whether OVOL2 regulates cancer metabolism.In this study,the transcription factor OVOL2 was screened by RNA-Seq under hypoxic conditions.RNA-Seq,RT-PCR and Western bloting experiments showed that OVOL2 inhibited the expressions of glycolysis genes both in vivo and in vitro and was a key factor in inhibiting glycolysis and glycolysis genes.Double luciferase activity and Ch IP assays showed that OVOL2 directly inhibited the promoter activity of several glycolysis genes and thus inhibited the expressions of glycolysis genes.IP and mass spectrometry analyses demonstrated that OVOL2 interacted with Nuclear receptor corepressor(NCoR),but not SMRT,a member of NCoR family,and OVOL2 formed a complex with NCoR/HDAC3.OVOL2 inhibited glycolysis through NCoR and Histone deacetylase 3(HDAC3).In addition,similar with OVOL2,NCoR also inhibited the transcriptions of several glycolysis genes,and OVOL2 was required to recruit NCoR to the promoters of glycolysis genes.Cell proliferation,invasion,in situ tumorigenesis and metastasis experiments indicated that OVOL2 inhibited glycolysis as well as proliferation,invasion and metastasis of breast cancer cells mainly through NCoR.OVOL2 blocked Warburg effect and the growth and metastasis of breast tumors.IP and Western blotting experiments showed that the E3 ubiquitin ligase MDM2(mouse double minute 2)degraded OVOL2 protein by ubiquitinating it.Tumor suppressor p53 could weaken the interaction between MDM2 and OVOL2 by binding MDM2,thus inhibiting OVOL2 ubiquitination and thereby increasing OVOL2 levels.Immunohistochemical analysis of clinical samples indicated that OVOL2 expression was negatively correlated with the expressions of glycolysis genes,which could be used as a good prognostic indicator for patients with breast cancer.In conclusion,targeting the p53/MDM2/OVOL2 axis provides a potential pathway for the treatment of cancers,especially breast cancer.