A Study On The Expression Of SH2-B In Colon Cancer And The Molecular Mechanism

Objective:To investigate the expression profile of SH2-B in colon carcinogenesis and its abnormal activation in the colon cancer,and explore the mechanism of SH2-B involving in colon carcinogenesis.Methods:Using immunohistochemistry assay,SH2-B expression was detected in 29 cases of colon cancers,27 cases of colonic adenomas, 29 cases of colonic polyps and 38 cases of nasopharyngeal carcinoma, then we gained the expression profile of SH2-B in colon carcinogenesis. HEK293 cells were transfected with the plasmids of pcDNA3.1-SH2-B using LipofecTAMINE 2000,and then SH2-B expression was determined by using Western-blotting assay after being transfected.To observe the promote effect of SH2-B on cell proliferation,the cell proliferation was measured using MTr assay.Results:(1) The results of immunohistochemistry assay showed that the positive rate of SH2-B in colon polyps tissues was 31%(9/29),the positive rate of SH2-B in colonic adenoma tissues was 52%(14/27),and the positive rate of SH2-B in colon cancer tissues was 93%(27/29),while the positive rate of SH2-B in nasopharyngeal carcinoma tissues was 87% (33/38).SH2-B expressed in cytoplast and cytoplasm of colonic polyps, colonic adenoma,colon cancer and nasopharyngeal carcinoma tissues,mainly located in cytoplasm.Image analysis revealed that the positive cell rate of SH2-B in colon cancer tissues(0.64±0.26) was significantly higher than that in colon polyps(0.12±0.21) and colon adenoma tissues(0.26±0.27)(P＜0.001),the positive cell rate of SH2-B in colonic adenomas tissues was significantly higher than colon polyps(P＜0.05),the positive cell rate of SH2-B in colon cancer tissues(0.64±0.26) was lightly higher than that in nasopharyngeal carcinoma tissues(0.49±0.28,P＜0.05).The score of staining intensity of SH2-B in colon cancer tissues(2.76±1.18) was significantly higher than that in colon polyps(0.72±1.16) and colon adenoma tissues(0.77±0.85,P＜0.0001),but there was no significant between colonic adenomas tissues and colon polyps tissues(P＞0.05).There was also no significant between colon cancer tissues(2.76±1.18) and nasopharyngeal carcinoma tissues (3.03±1.30,P＞0.05),it showed that SH2-B may involve in colon carcinogenesis.(2) In cell proliferation experiments,we transfected the plasmids of pcDNA3.1-SH2-B to HEK293 cells and used Western-blotting assay to analyze the SH2-B expression,the results showed that pcDNA3.1-SH2-B expression dramatically increased in HEK293 after gene tansfection.Using MTT assay to detected the cell proliferation after gene transfection,the cell proliferation was significantly strong(P＜0.05).The results suggested that the significantly high expression of SH2-B in the process of colon carcinogenesis may promote abnormal proliferation of epithelial cells.Conclusions:(1) Colon cancer is a multi-stage complex process, which a lot of factors and genes involved in.SH2-B expression in the colonic polyps,colonic adenoma and colon cancer tissues gradually increases.We speculate that SH2-B may be an early event in colon carcinogenesis,and it may play an important role in the early stage of colon carcinogenesis;(2) SH2-B promotes cell to proliferate abnormally, and this may be one of the important mechanisms in colon carcinogenesis.