Clinical Study On The Expression Of E-cadherin And β-catenin In Human Advanced Colorectal Carcinoma And Metastatic Lymph Nodes

Objective: The aim of this study was to investigate the expression of epithelialcadherin (E-cad) andβ-catenin (β-cat) mRNA and protein in human advanced colorectal carcinoma and their metastatic lymph nodes, discuss the correlation between the expression of E-cad,β-cat and the biological behaviour of colorectal carcinoma, and explore a new possible target on molecular level to diagnosis and treat colorectal carcinoma.Methods: Immunohistochemistry was used to respectively detect the expression of E-cad andβ-cat in 57 cases of advanced colorectal carcinoma muscous (32 cases have metastatic lymph nodes) and 25 cases of normal colorectal muscous. The examination of the expression of E-cad andβ-cat in 32 colorectal carcinoma primary foci and metastatic lymph nodes by means of immunohistochemistry, western blot, RT- PCR and flow cytometry was to analyze the mechanism of the re-expression of E-cad andβ-cat in metastatic lymph nodes.Results: Immunohistochemistry showed that the abnormal expression rate ofβ-cat and E-cad were 71.9% (41/57) and 68.4% (39/57) respectively in 57 colorectal cancer muscous, which were different significantly from that in 25 normal colorectal muscous. The abnormal expression of E-cad andβ-cat were significantly correlated with tissues differentiation digree and lymph nodes metastasis states (P<0.05). The abnormal expression rate of E-cad in colorectal cancer was still correlated with histological type (P<0.05). There was correlation between the expression ofβ-cat and the depth of cancer invasion (P<0.05). Besides, the abnormal expression rate ofβ-cat and E-cad were positively related, which were associated with lymph nodes metastasis (P<0.05). The result of respective dectetion of E-cad andβ-cat in 32 colorectal carcinoma primary foci and their corresponding metastatic lymph nodes: (1) Immunohistochemistry showed respectively that the abnormal expression rates of E-cad andβ-cat were 90.6% (29/32) and 84.4% (27/32), and the re-expression rate of E-cad andβ-cat in metastatic lymph nodes were 37.5% (12/32) and 43.8% (14/32). The re-expression rate of E-cad andβ-cat in well-differentiated and moderately-differentiated carcinoma were 55.6% (10/18) and 61.1% (11/18) respectively, in poorly-differentiated colorectal carcinoma were 14.3% (2/14) and 21.4% (3/14). The above differences have statistical significance (P<0.05). The abnormal re-expression rate of E-cad was correlated with histological type of tumor. The re-expression rate of E-cad in metastatic lymph nodes from tubular and papillary adenocarcinoma was 52.4% (11/21), in mucous adenocarcinoma was 0.9% (1/11) (P<0.05). The re-expression rate ofβ-cat was not correlated with tumor histological type (P>0.05). The re-expression rate of E-cad andβ-cat were not correlated with the invasion depth, tumor size, tumor location and patiernt age (P>0.05). The re-expression rate ofβ-cat were positively related to that of E-cad (P<0. 05). (2) Western blot showed that in primary foci, the protein relative strength of E-cad andβ-cat were 6～107(64.25±36.46) and 5～89(33.9±25.44) respectively, and in metastatic lymph nodes, that were 13～149(84.41±36.75) and 9～105(53.61±31.54). The protein relative intensity of E-cad andβ-cat in metastatic lymph nodes were higher than that in primary foci (P<0.05). While, the relative intensity of E-cad andβ-cat protein in the metastatic lymph nodes from well-differentiated and moderately-differentiated adencarcinoma were 28～127(98.56±36.09) and 21～106(63.74±30.69) respectively, in poorly differentiated adencarcinoma were 11～62(66.21±29.74) and 7～49(35.69±25.10). The all of above differences have statistical significance (P<0.05). The relative intensity of E-cad protein in metastatic lymph nodes was still significantly correlated with the tumor histological type. (3) RT-PCR showed that the relative expression value of E-cad mRNA andβ-cat mRNA in primary foci were (0.733±0.009) and (0.709±0.011) respectively, and in metastasis lymph nodes that were (0.739±0.010) and (0.728±0.007), which was significantly higher than that in primarily foci, but lower than that in nomal muscous (P<0.05). The result indicated that the re-expression of E-cad mRNA andβ-cat mRNA in metastatic lymph nodes were associated with differentiation digree (P<0.05). The re-expression of E-cad mRNA was associated with tomor histological type (P<0.05). (4) The result from FCM showed that the relative fluorescence intensity of E-cad andβ-cat in primary foci was lower than that in metastatic lymph nodes (P<0.05). In metastatic lymph nodes, the relative fluorescence intensity of E-cad in tubular and papillary adenocarcinoma was higher than that in mucous adenocarcinoma.Conclusion: The function status of E-cad andβ-cat may be closely associated with the occurrence, invasion and metastasis of colorectal carcinoma. The abnomal expression of E-cad andβ-cat were generally exist in human advanced colorectal carcinoma, and they were significantly correlated with the malignant biology phaenotype of colorectal carcinoma and lymph nodes metastasis. E-cad andβ-cat play a cooperative role in the process of invasion and metastasis of tumor. The high re-expression rate in metastatic lymph nodes indicate: may be the abnomal expression of E-cad andβ-cat result in cancer cells's separating from primary foci, and the re-expression improve cacer cells assemble again in metastatic lymph nodes, This point prove that the protein expression of E-cad andβ-cat exist some certain spatiality and timeliness. The union detection of E-cad andβ-cat on the level of gene and protein by means of western-blot,RT-PCR and FCM indicate that the their re-expression in metastatic lymph nodes may be derived from the gene mutation. The protein and gene of E-cad andβ-cat provide an important possible target for interrupt or control colorectal carcinoma metastasis.