Minichromosome maintenance 2 (MCM2) immunoreactivity in stage III human gastric carcinoma: clinicopathological significance

Background. The origin licensing factor minichromosome maintenance 2 (MCM2) has recently been identified as a critical regulator of proliferation in both normal and neoplastic cells. This study examined whether MCM2 expression was of prognostic relevance in patients with stage III gastric carcinoma and whether the expression of this marker showed any correlation with clinicopathological characteristics. In addition, we evaluated whether the expression of this proliferation marker was correlated with that of another marker, Ki-67, in gastric carcinoma. Methods. We examined the immunohistochemical expression of MCM2, Ki-67, and p53 in 103 surgically removed stage III gastric carcinomas, which consisted of 60 intestinal-type and 43 diffuse-type carcinomas. The labeling indices (LIs) of MCM2 and Ki-67 in cancer cells were compared with clinicopathological characteristics, p53 expression, and overall survival rates. Results. The mean MCM2 and Ki-67 LIs were 69.1 +/- 11.8% and 48.2 +/- 14.5%, respectively, in the intestinal carcinomas, and 43.7 +/- 9.9% and 24.9 +/- 11.0%, respectively, in the diffuse carcinomas. The LIs of these proteins revealed no significant association with clinicopathological characteristics or with p53 expression in the carcinomas. Kaplan-Meier survival curves showed that, in the patients with diffuse carcinoma, those with higher MCM2 LIs had a poorer prognosis (P < 0.05), but the MCM2 LI was not correlated with prognosis for those with intestinal carcinoma (P = 0.25). Ki-67 expression had no significant correlation with prognosis in either intestinal-type or diffuse-type carcinomas. Multivariate Cox regression analysis confirmed that MCM2 was an independent prognostic factor in patients with diffuse carcinoma. Conclusion. Our data suggest that MCM2 is a useful prognostic marker in patients stage III diffuse-type gastric carcinoma.