Expression Of E-cadherin And β-catenin In Colorectal Carcinoma And The Clinical Significance

PURPOSEWe performed E -cadherin and b -catenin expression investigation with immunohistochemical method on colorectal cancer in order to elucidate whether the expression of E - cadherin and b - catenin correlate with clinicopathological variables and prognosis.Materials and methodsSpecimensThe specimens of cancer tissues were taken from 139 consecutive patients with colorectal adenocarcinoma who had undergone resection from January to June in 1996 at Liaoning Cancer Hospital . And the specimens of normal tissues were taken from the resected colorectal spicemens above 10cm far from cancer.Immunohistochemical stainingFour micrometers thick sections prepared from formalin - fixed and paraffin - embedded tumor tissue or normal tissue on the slides were stained immunohistochemically with the primary antibodies as mouse monoclonal- and - human E - cadherin or (3 - catenin ( Fu Zhou Maxim Biotechnology, ready to use) and the SP kit ( Fu Zhou Maxim Biotechnology).Normal mucosal epithelium served as an internal positive control and adjacent normal mucosal epithelium as an.internal positive control. Negative control was obtained by replacing the primary antibody with PBS.Evaluation of immunohistochemical stainingIn normal mucosa, the membranous staining of cells were positively stained with brown by the antibody. Calculating the percentage of positively stained cells evaluated for each tissue section after counting 100 cells at more than 5 high - power ( x400) fields. The expression of E - cadherin and b - catenin were classified as follows: If more than 90 % of the tumor cells were positively membranous stained, the expression was judged to be normal; If less than 90 % of the tumor cells were positively membranous stained, the expression was judged to be abnormal, as well as elevated cytoplasmic and/or nuclear staining.Statistical analysisAll the statistical analyses were performed using the SPSS 10.0 V for Windows software.RESULTSThe results shown that normal colorectal epithelium showed strong expression of E - cadherin and b - catenin at the membrane of cell and the intercellular junctions. No or weak cytoplasmic staining of E -cadherin and b - catenin were seen in nonnal colorectal epithelium. Reduced homogenous and heterogeneous membranous staining of E -cadherin and b - catenin were found in colorectal carcinoma, as well the abnormal staining of b - catenin in cytoplasm and/or nuclei . Re-duced membranous expression of E - cadherin and b - catenin was found in 69. 8 % (97/139) and 70. 5 % (98/139). And abnormal cytoplasmic and/or nuclear expression of b - catenin were found in 75.5% (105/139). Significant inverse correlation existed between the abnormal expression of E - cadherin and histologic grade, lymph node metastases, and clinical staging. Abnormal expression of b - catenin correlated significantly only with histologic grade. The median survival was 54 months and overall 1 - , 3 - , 5 - year survival rates were 94. 2 % , 61.9 % and 50.4 % , respectively. There obviously existed inverse correlation between abnormal membranous expression of E - cadherin and b - catenin and poor survival. No significant correlation was apparent between abnormal cytoplasmic and/or nuclear expression of b - catenin and overall survival.CONCLUSIONThe cadherin - catenin complex may have a major role in cell -cell adhesion systems, and abnormal membranous expression of E -cadherin and b - catenin correlates with invasion and metastases, as well an unfavorable prognosis.