Effect And Mechanism Of SET7 On The Development Of Colon Cancer By Regulating Deacetylation Of HDAC6

Background and objective: Colorectal cancer(CRC)it is the fourth most deadly cancer worldwide(after lung,liver,and stomach cancers).Histone deacetylase 6(HDAC6)is a unique class IIb histone deacetylase and SET7(also known as SET7/9 and SETD7)is a histone methyltransferase.Previous studies have shown that both HDAC6 and SET7 play an important role in the development of CRC.So far,role of SET7 and HDAC6 in CRC and its underlying mechanism are still unclear.Therefore,this study aims to explore the effect and mechanism of HDAC6 and SET7 on CRC,and provide new strategies for the treatment of CRC.Methods:1.Mining and analyzing SET7 expression in normal and colorectal cancer tissues from public databases HPA,GEO,and GEPIA to evaluate relationship between SET7 expression and clinicopathological characteristics.2.Cell proliferation and migration were detected by cell counting kit8,wound healing and transwell assays in SET7 overexpression and knockdown experiments.3.Overexpression SET7 and HDAC6 in colon cancer cell lines,their interaction effect and SET7 specific domains that interacted with HDAC6 were verified by co-IP and confocal microscopy experiments.Assessing effects of SET7 on colon cancer cell phenotype,deacetylation and ERK/MAPK signal pathway treated with HDAC6.4.SET7 MORN domain reduced ACE2 expression in colon cancer cells.5.Mining and analyzing ACE2 expression in normal and colorectal cancer tissues from HPA,GEO and GEPIA databases.Effects of ACE2 on cell proliferation and apoptosis were detected by CCK8,clone formation,flow cytometry assays.Results:1.Both SET7 m RNA and protein levels were highly expressed in adjacent normal tissues than that cancer tissues.2.Overexpression SET7 reduced cell proliferation and migration in colon cancer cell lines.Knockdown SET7 upregulated cell proliferation and migration in colon cancer cell lines.3.Both full-length of SET7(GFP-SET7-FL),MORN domains(GFPSET7-D1)and intermediate regions(GFP-SET7-D4)of SET7 were involved in HDAC6 interaction.Overexpression SET7 reduced cell proliferation and migration and downregulated deacetylation of a-tubulin and ERK/MAPK signal pathway induced and activated by HDAC6.4.Western bloting results indicated SET7 MORN domain reduced ACE2 expression.5.ACE2 m RNA and protein expression were highly expressed in colon cancer tissues compared with adjacent normal tissues.Knockdown ACE2 redeced cell proliferation and migration in colon cancer cells.Conclusion:1.SET7 is lowly expressed in CRC patients,and related with poor prognosis.2.SET7 MORN domain is the key domain that interacted with HDAC6.3.SET7 regulated deacetylation of HDAC6 and reduced cancerpromoting effects induced by HDAC6.4.SET7 MORN domain reduced ACE2 expression,knockdown ACE2 promoted DNA damage and apoptosis in colon cancer cells.