Study On The Expression And Mechanisms Of MicroRNA-21 In Ulcerative Colitis And Ulcerative Colitis Related Colorectal Cancer

Background and ObjectivesThe incidence of ulcerative colitis(UC)is increasing anually,but the etiology is still unclear.Ulcerative colitis related colorectal cancer(UCRCC)is one of the major complications of UC.Studies have shown that the severity of micro-inflammation in the colon tissue is an independent risk factor for the development of UC carcinogenesis.Multiple studies have confirmed that miR-21 and miR-223 are highly expressed in colon tissues and peripheral blood of patients with UC and UCRCC,but the mechanism of these two kinds of miRNAs in UC inflammation and carcinogenesis remains to be further studied.This study aimed to detect the expression of miR-21,miR-223,corresponding target mRNA and inflammation cytokine in a mouse model,while further explore the effects of miRNA knockdown and overexpression on cell cycle and apoptosis in colon cancer cells,and check the expression change of inflammation cytokine and target mRNA to find the mechanism of miRNA toward UC inflammation and carcinogenesis.MethodsDSS was used to construct acute colitis mouse model,while AOM/DSS was used to construct colitis associated colorectal caner(CAC)mouse model.We used qRT-PCR to screen the expression of miR-21,miR-223,corresponding target mRNA and inflammation cytokine in the colon tissues of the mouse models.After the construction of miR-21 knockdown and overexpression in colon cancer cell lines,we used qRT-PCR to detect the expression of inflammation cytokine and the corresponding target mRNA,and the flow cytometry to detect the apoptosis rate and cells cycle phase.ResultsmiR-21 is significantly upregulated in colon tissues of acute colitis and CAC mouse model(P<0.01).GAS5 is significantly downregulated in colitis and CAC mouse model,and is negatively correlated with miR-21.The expression of IL-1?,IL-6 and TNF-? is significantly increased in colitis mouse model and CAC model,consistent with the miR-21 expression levels(P<0.01,P<0.01,P<0.05).There's no difference of the expression of miR-223 between colitis,CAC mouse model and control group(P?0.5).BL-1?,IL-1? and IL-6,IL-8,IL-10,IL-17A are significantly decreased in miR-21 knockdown cells(P<0.001,P<0.05,P<0.05,P<0.01,P=0.0001,P<0.05).miR-21 knockdown cells increased in the G2/M phase(31.6%?33.5%).Conclusion1.miR-21 may participate in mouse colon inflammation by down-regulating the expression of GAS5.miR-21 may participate in colon inflammation and carcinogenesis in mouse model by up-regulating the expression of inflammation cytokines IL-1?,IL-6 and TNF-a.2.Knockdown of miR-21 in colon cancer cell lines may inhibit the inflammation by down-regulating the expression of the IL-l?,IL-1? and IL-6,IL-8,IL-10,IL-17A.3.Knockdown of miR-21 may inhibit cell cycle in the G2/M phase to reduce cell proliferation.