Expression of minichromosome maintenance 2 (MCM2), Ki-67, and cell-cycle-related molecules, and apoptosis in the normal-dysplasia-carcinoma sequence of the oral mucosa

Abstract

Objective: We examined cell cycle and cell death biomarker trends with the normal-dysplasia-carcinoma sequence of the oral epithelia analyzing the pathological significance of a new biomarker, minichromosome maintenance 2 (MCM2).

Methods: This study analyzed 12 patients with normal oral epithelia, 69 with dysplasia, and 35 with squamous cell carcinoma (SCC); in 13 patients, SCCs were preceded by dysplasia. The sections were immunostained for MCM2, Ki-67, P53, P27(Kip1) and P21(CIP1/WAF1), and conducted by TUNEL methods. Western blot analysis of MCM2 was performed in the 4 human cultured oral SCCs, all of which showed the expression.

Results: Significantly higher labeling indices (LI; %) of MCM2, Ki-67, and P53, as well as lower LI of TUNEL indices (TI; %), P27, and P21 were noted in the SCCs than in the dysplasias. The 13 dysplasias developed SCC with significantly higher LI of MCM2 and P53, and lower LI of P21 than the other dysplasias (each p < 0.05). The LI of MCM2, P21 and the TI were not correlated with P53 expression.

Conclusions: Oral dysplasia was characterized by lower cell proliferation and a higher frequency of cell death compared to SCCs. The higher LI of MCM2 and P53 and the lower LI of P21 might predict malignant transformation of oral dysplasia. MCM2 is regulated via a P53-independent pathway, and a useful biomarker of proliferating cells.