Minichromosome maintenance-7 and geminin are reliable prognostic markers in patients with oral squamous cell carcinoma: immunohistochemical study

Background: Minichromosome maintenance (MCM) proteins act as the origin licensing machinery that regulates initiation of DNA replication. Geminin is a licensing repressor and prevents reinitiation of DNA replication by blocking reloading of MCM proteins at replication origins. Recent studies have proposed that MCM7 and geminin may be sensitive proliferative and prognostic markers of various malignant tumors. This study aimed to analyze the expression of MCM7 and geminin to clarify pathobiological significance in human oral squamous cell carcinomas (OSCCs). Methods: We performed immunohistochemical analysis on 10 specimens of normal oral epithelia, 50 lesions with dysplasia and 113 OSCCs. Labeling indices (LIs) for MCM7, geminin and Ki-67 were evaluated, comparing with clinicopathological profiles. Results: The mean LIs for MCM7 were 29.2% for normal epithelia, 32.2% for dysplasias, and 51.1% for OSCCs; the value was significantly higher in the last than in the former two (P < 0.01). The mean LIs for geminin were 6.8% for normal epithelia, 9.2% for dysplasias, and 21.3% for OSCCs; the value was significantly higher in the OSCCs (P < 0.01). The MCM7 LIs were correlated with the histological grade of OSCCs, in which the highest LIs were noted in the poorly differentiated type (P < 0.01). The survival rate was significantly lower in patients with a higher MCM7 LI (> 49.5%) than in those with a lower LI (P < 0.05) at stage III-IV. However, the survival rate in the patients with a higher geminin LI (> 19.5%) was significantly higher than in those with a lower LI (P < 0.05) at stage IV.