The Association Of Polymorphisms In RUNX3 With Ulcerative Coliti

Ulcerative colitis (UC) is a chronic and non-specific inflammatory disease, and it belongs to inflammatory bowel disease (IBD) which comprises Crohn's disease (CD), ulcerative colitis (UC) and indeterminate type of colitis. The pathogenesis of UC is not clear. In western countries, the accidence rate of UC is higher than that in Asian. The accidence rate of UC is increasing gradually in our country. It is commonly presumed to be a multifactor disease caused by the effect of enterobacteria and environmental factors on the hereditary susceptibility cohorts, and presented with excessive immunoreactions in intestinal mucosa. Epidemiological evidence shows a strong hereditary susceptibility contribution to UC including high incidence of UC in certain ethnic groups, family-cluster phenomenon and the concordance in identical twins. Recently, some important progresses have been made on the predisposing genes of IBD by gene linkage analysis. Many chromatosome location of IBD predisposing genes were found, which are respectively called IBD1-7. And several UC predisposing genes were confirmed in different population. For example, SLC22A4 and SLC22A5 gene was identified as the susceptibility locus for UC and CD in Italians, and the result were duplicated in the Caucasian population from England too. But UC belongs to polygenic inheritance disease. It is difficult to make clear the complicated relation between its genotype and clinical phenotype. Because of its genetic heterogeneity, especially the great difference between eastern and western population, many research achievement in western country can't be duplicated in the Asian. So, much still needs to be done to find a widespread UC predisposing gene in the future.Recently, several study from Nature Genetics magazine discover some predisposing genes of autoimmune disease, such as systemic lupus erythematosus (SLA), rheumatoid arthritis(RA) and psoriasis, whose polymorphism disrupted the binding site for seemed to be the RUNX1 transcription factor. These studies indicated that there is a common molecular mechanism in auto-immunologic derangement appearance. Because the three RUNX proteins have identical DNA-binding and heterodimerization domains, three runxs proteins may all play an important role in autoimmune disease. RUNX3 belongs to the runt domain family of transcription factors, which has been mapped to locus 1p36.1. Linkage study and association study suggested that a fragment on chromosome 1p36 which RUNX3 has been mapped was associated with IBD risk. Ori Brenner report that Runx3 knockout mice, at 4 weeks of age, spontaneously develop inflammatory bowel disease (IBD). However, the function of RUNX3 in pathogenesis of UC remains not fully understood. So in the present work, we investigated that whether polymorphisms in RUNX3 and its downstream genes is associated with ulcerative colitis.Objective(1) To investigate whether RUNX3 expression level is associated with pathogenesis of UC; (2) To screen the downstream effectors of RUNX3 and find some new targets associated with ulcerative colitis; (3)To detect the genetic polymorphism of RUNX3 and its downstream genes and its relationship with UC in a large population of independent Chinese Han.Methods(1) Immunohistochemical method was used to detect the expression of RUNX3 in colonic mucosa from 68 patients with UC and 50 normal tissues adjacent colorectal carcinoma as normal controls. (2) To screen the downstream effectors of RUNX3 by Chip-chip technology. (3)The study population comprised 81 patients with UC and 154 healthy controls from Chinese Han people. The genetic polymorphisms of those genes (RUNX3 rs2236851C/T, SLC22A4 rs3792876C/T and PPAR-γrs3892175A/G) were analyzed by PCR–SSP. Data were analyzed byχ2 test by SPSS statistic software.Results(1) Immunohistochemical results showed that the positive rates of RUNX3 were 76.5% (52/68) in the ulcerative colitis tissues and 66.0 %( 33/50) in the normal controls respectively. Statistical analysis suggested that the positive rates of RUNX3 were not significantly different between the ulcerative colitis and normal controls (P >0.05), and the expression of RUNX3 is not associated with age, sex, grade and disease location.(2) By Chromosome immunoprecipitation technology, the total DNA fragments of RUNX3 downstream genes were harvested from SGC7901 cell. Then, the sample was sent to Beijing CapitalBio Corporation. After microarray hybridization, image collection and data normalization, 698 genes were got which may be regulated directly by RUNX3. Among 698 genes, PPAR-γseems to have close relation with UC.(3) RUNX3 gene (rs2236851C/T) has polymorphisms in Chinese Han people, and T allele frequency was 18.49% in UC group, which was higher than control group (7.75%). RUNX3 genotype distribution : TC36.99%,CC63.01% in UC group;TC15.49%,CC84.51% in control group. Date analysis revealed that the individuals carrying more variant A genotype had higher risk of UC. Consistently, the RUNX3 genotypes with variant alleles (rs2236851C/T) were associated with an increased risk of UC. There were SLC22A4 gene(rs3792876C/T) and PPAR-γgene(rs3892175A/G)polymorphisms in Han people, but they were not associated with UC.ConclusionWe provide evidence that RUNX3 expression was not significantly different between the ulcerative colitis and normal controls. But our study revealed that RUNX3 gene (rs2236851C/T) has polymorphisms in Chinese Han people and its polymorphism was associated with UC. SLC22A4 gene(rs3792876C/T) and PPAR-γgene(rs3892175A/G)show genetic polymorphisms in Chinese Han people , which were ,nevertheless, not associated with UC.