Clinical Significance of MCM-2 and MCM-5 Expression in Colon Cancer: Association with Clinicopathological Parameters and Tumor Proliferative Capacity

Minichromosome maintenance (MCM) proteins are essential components of DNA replication, being related to cell proliferation, and serve as useful markers for cancer screening, surveillance, and prognosis. Our aim was to examine the clinical significance of MCM-2 and MCM-5 protein expression in colon cancer and to evaluate the association with various clinicopathological characteristics and tumor proliferative capacity. Immunohistochemical expression of MCM-2 and MCM-5 was performed on paraffin-embedded malignant tissue sections obtained from 96 patients with colon cancer. MCM-2 and MCM-5 expression was correlated with different clinicopathological characteristics, proliferative capacity (Ki-67 labeling index), and p53 cell-cycle regulator expression. MCM-2 and Ki-67 expression was significantly associated with the tumors' histological grade (P = 0.003), existence of nodular metastases (N) (P = 0.003 and P = 0.030, respectively), malignancy on adenoma (P = 0.029 and P = 0.024, respectively), and vascular invasion (P = 0.010 and P = 0.011, respectively). MCM-2 expression was additionally associated with Dukes' stage (P = 0.005). Significant positive relationships were found between the expression of MCM-2 or MCM-5 proteins and that of Ki-67 protein (r = 0.963, P-value < 0.001, and r = 0.738, P-value < 0.001, respectively), as well as between MCM-2 and MCM-5 proteins (r = 0.745, P-value < 0.001). Significant positive relationships were also observed between the expression of MCM-2 or MCM-5 proteins and that of p53 protein; however, they were consistently lower than the corresponding with Ki-67 protein. No significant association was observed between MCM-5 protein expression and the clinicopathological characteristics examined. The current data suggest that MCM-2 protein expression is significantly associated with important clinicopathological characteristics for patients' management, being correlated with the cell proliferation state in colon cancer.