The Underlying Mechanism Of Susceptibility Locus 16q22.1 And Its Downstream Gene ZFP90 Involving In The Initiation And Progression Of Colorectal Cancer

Objective: 16q22.1 locus is one of susceptibility loci of colorectal cancer(CRC)found through genome-wide association study(GWAS).However,the specific molecular mechanism by which it promotes initiation and progression of CRC is poorly understood.This study aimed to explore the regulatory relationship between the susceptibility locus 16q22.1 and the remote downstream gene ZFP90 and their biological function in the initiation and progression of colorectal cancer.Content and methods: We detected the genotypes of single Nucleotide Polymorphism rs9929218(SNP-rs9929218)and surrounding genes in 16q22.1 region in 60 colorectal cancerous tissues and paired normal colorectal epithelial tissues.The relationship between these two was analyzed by linear correlation analysis.Downstream genes regulated by the 16q22.1region were further identified using chromatin conformation capture technology in colorectal cancer cell lines carrying different genotypes.The biological function of downstream gene ZFP90 was further clarified by gene-knockout animal models,cellular functional experiments and chromatin immunoprecipitation assay.Combined with clinicopathological information,the relationship between ZFP90 expression and the clinical phenotype including prognosis of patients with colorectal cancer was clarified.Results: In the colorectal epithelium,there was a significant correlation between the genotypes of 16q22.1(SNP-rs9929218 G/ A)and the expression level of ZFP90.The region on the left side of SNP-rs9929218 has a long-range interaction with the promoter region of ZFP90.Moreover,The strength of the interaction between these two depends to a large extent on the genotype.In the AOM-induced mouse CRC model,the number and volume of tumors in ZFP90-knockout group were significantly less than those in wild-type group.After knocking out ZFP90 in various colorectal cancer cell lines,their stemness and proliferation ability obviously decreased.Using gene-set enrichment analysis and chromatin immunoprecipitation assay,we found that ZFP90 can regulate BMP-SMAD pathway and Hedgehog pathway.In particular,ZFP90 can transcriptsionally inhibit the key ligand genes BMP4 and IHH.Moreover,The expression level of ZFP90 is correlated with tumor stage,histological grade and prognosis in patients with colorectal cancer.Conclusions: The CRC susceptibility locus 16q22.1(Region on the left side of SNP-rs9929218)can be act as an enhancer to remotely control the expression of ZFP90.ZFP90 can promote the initiation and progression of colorectal cancer by negatively regulating the key genes BMP4 and IHH in colorectal cancer to enhance the stemness of colorectal epithelial cells.