Expression of .ALPHA.-catenin and E-cadherin in oral squamous cell carcinoma and association with metastasis to regional lymph nodes and survival rate.

α-Catenin (α-cat), one of the E-cadherin (E-cad) associated cytoplasmic proteins that forms linkages to the cytoskeleton, regulates the functions of E-cad. Since the expression of E-cad, an intercellular adhesion molecule, has been suggested to contribute to metastasis of the same type of tumor, I hypothesized that the examination of α-cat may also help to evaluate the ability of a tumor to metastasize. In the present study, therefore, the expression of α-cat in oral squamous cell carcinomas (SCCs) obtained by biopsy from 84 patients was examined immunohistochemically with the use of a monoclonal antibody. The relationship between the staining patterns for α-cat and clinicopathological findings was analyzed and compared with that for E-cad.α-Cat showed circumferential staining and/or cytoplasmic staining in SCC cells, while E-cad showed circumferential staining. The expression of α-cat and E-cad was classified as follows: 1) positive, almost all cells were strongly stained and the staining was equivalent to that in normal oral squamous cells; 2) weakly positive, some cells were stained, but the remaning cells were not stained or were weakly stained. 3) negative, almost all cells were not stained. The incidence of metastasis to regional lymph nodes in cases negative for α-cat was significantly higher (66.7%) than that in the combined total of positive and weakly positive cases (23.3%)(p=0.0005). Moreover, the survival rate differed significantly between negative (64.3%) and weakly positive cases (91.3%), as well as between weakly positive and positive cases (100%)(p<0.05). As for E-cad expression, the incidence of metastasis and the survival rate in negative cases were similar to the results obtained for α-cat expression in this study. However, 69%(58/84) of the cases showed weakly positive staining for E-cad, and the incidence of lymph node metastasis in this group was 37.9%(22/58) which was similar to that in all 84 cases (30/84, 35.7%). The results suggests that the rate of lymph node metastasis could not be accurately estimated in more than half of the patients. By additionally performing α-cat staining, α-cat negative cases among weakly positive cases for E-cad were found to have a significantly higher incidence of lymph node metastasis than the combined total of weakly positive and positive cases did (p=0.0423).In conclusion, the combined examination of α-cat and E-cad expression in oral SCC yields useful information concerning regional lymph node metastasis and prognosis.