Expression and significance of APC and β-catenin proteins in colorectal carcinoma

Objective To investigate the role of APC and β-catenin in the carcinogenesis and progression of colorectal carcinoma.Methods Expression of APC and β-catenin proteins was detected by immunohistochemistry in 30 cases of normal colorectal mucosa,30 cases of colorectal adenoma,10 cases of colorectal adenoma carcinogenesis and 50 cases of colorectal carcinoma.Results The positive expression rates of APC were 44.0% and 40.0% respectively in colorectal carcinoma and colorectal adenoma carcinogenesis,and both of the rates were significantly lower than that of colorectal adenoma(86.7%) and normal colorectal mucosa(100.0%)(P0.01).The cytoplasmic and nuclear β-catenin expression rates were 62.0%,50.0% and 30.0% respectively in colorectal carcinoma,colorectal adenoma carcinogenesis and colorectal adenoma,and all of the rates were significantly higher than that of normal colorectal mucosa(0%)(P0.01).The cytoplasmic and nuclear β-catenin expression rate in colorectal carcinoma was significantly higher than that of colorectal adenoma(P0.01).The reduced membranous β-catenin expression rate in colorectal carcinoma was significantly higher than that of colorectal adenoma and normal colorectal mucosa(P0.01).The reduced membranous β-catenin expression was closely related with the tissue defferentiation degree,the depth of invasion,lymph node metastasis and Dukes stage in colorectal carcinoma.The cytoplasmic and nuclear β-catenin expression was in negative correlation with the expression of APC(r=-0.39,P0.05).Conclusion The reduced cytoplasmic APC expression,the cytoplasmic and nuclear β-catenin expression may play a pivotal role in carcinogenesis and progression of colorectal carcinoma,and may be an early event.The reduced membranous β-catenin expression may be related to the invasion and metastasis of colorectal carcinoma.