Expression Of APC And β-catenin Gene And Their Clinical Significance In Human Sporadic Colorectal Carcinoma

ObjectiveTo explore the role of APC and β -catenin in the carcinogenesis and progression ofsporadic colorectal adenocarcinoma.MethodsImmunohistochemical methods were used to detect the expression of APC and β -catenin protein in 45 cases of normal colorectal mucosa, 33 cases of sporadic colorectal adenoma, 55 cases of sporadic colorectal carcinoma,and the results were correlated with clinicopathological tumor parameters. Results(1) The percentage of APC protein loss expression in colorectal adenocarcinomas (76.4%) was significantly greater than that in colorectal adenomas (27.3%) and normal colorectal mucosa tissues (13.3%)( P<0.05).(2) The negative rate of APC protein expression in colorectal villous adenomas was significantly greater than that in colorectal tubular adenomas and mixed adenomas.(3) There were no significant difference in the incidence of APC protein expression in sporadic colorectal adenocarcinoma among the different age ,sex groups and the different site ,size, histopathological type , lymph node involvement, differentiated degree, Dukes' stage groups.(4) The percentages of β -catenin nuclear expression in the colorectaladenocarcinomas (88%) and adenomas (69.7%) were significantly greater than that in normal mucosa tissues (0%)(P<0.05).(5) The positive stain rate of β -catenin nuclear expression in moderate ,well differentiated colorectal adenocarcinomas (19/23 13/19 respectively) was less than that in poorly differentiated colorectal adenocarcinomas (13/13)( P<0.05).The percentage of β -catenin nuclear expression in lymphonodi metastases group (92.6%)was greater than that in non-lymphonodi metastases group (71.4%)( P<0.05).Thenuclear positive rate of β -catenin protein expression in the Dukes' A B stage groupwas lower than that in Dukes' C D stage group. There was no significant differences inthe incidence of !-catenin protein expression among different age ,sex groups anddifferent site, size of the colorectal adenocarcinomas groups.(6) There was an inverse correlation between APC and β -catenin protein expressionin colorectal adenocarcinomas and there was no correlation between loss of APC andnuclear accumulation of β -catenin in colorectal adenomas.Conclusion(1) APC and β -catenin protein plays an important role in carcinogenesis of sporadiccolorectal adenocarcinomas. Aberrant expressions(loss of APC expression ,nuclearaccumulation of β -catenin) of APC and β -catenin in sporadic colorectaladenocarcinomas are an early alteration. The major cause of β -catenin nuclearaccumulation in colorectal tumors is dysfunction of APC.(2)Loss of APC protein production expression may be associated with susceptibility of transformation from benign adenoma to adenocarcinoma in large bowel. (3)Abnormal nuclear expression of β -catenin in sporadic colorectal adenocarcinoma is associated with metastasis, de-differentiation and malignant behavior of tumors. (4)The detection of the expression of APC and β -catenin in colorectal carcinomas is valuable for evaluating the biological behavior of colorectal carcinomas and is beneficial to focal follow-up and repeat endoscopic control for diagnostic and clinical purposes.