Immunohistochemical Study of Metallothionein Expression in Colonic Adenocarcinoma: Correlation with p53, Topoisomerase II-alpha Expression and Apoptosis

ABSTRACT

PURPOSE: Although immunohistochemically detectable metallothionein (MT) overexpression has been described in proliferation epithelial tumor cells, the clinical significance of the expression remains to be elucidated. Therefore, the present article is focused on evaluating the possible significance of MT expression in colonic adenocarcinoma and its relationship with p53 overexpression, Topoisomerase II-alpha as new cell proliferating marker and apoptosis. METHODS: The following formalin-fixed paraffin embedded surgical or biopsied samples were immunohistochemically stained for MT, p53 and topoisomerase II-alpha, and performed in situ TUNEL method for evaluation of apoptotic cell ; normal control mucosa (78 cases), tubular adenomas (20 cases) and adenocarcinomas with various degree of differentiation (78 cases). RESULTS: The MT immunohistochmical reactivity was decreased in colonic adenocarcinoma than that of normal glandular epithelial and tubular adenoma, with the frequency of MT expression in colonic adenocarcinoma depending upon tumor differentiation only. But the frequency of p53 expression was correlated with T-stage, lymph node metastasis and clinical staging, while topoisomerase II-alpha expression and apoptosis in colonic adenocarcinoma were correlated with lymph node metastasis and clinical staging. The immunohistochemical expression of MT and p53 expression in colonic adenocarcinoma was inversely correlated. Also, the inverse correlation between MT expression and expression of toposiomerase II-alpha indices and apoptotic indices were noted. CONCLUSION: These data suggest that MT expression may play a role in proliferative activity and apoptosis in colonic adenocarcinoma. Although MT expression is correlated to tumor differentiation, further studies of a possibility of prognostic factor, such as p53, are required for the determination of significant relationships in other clinicinopathologic indices.