Assessment of Proliferative Index Between the Tumor Margin, Center of Tumor, and the Invasive Tumor Front of Oral Squamous Cell Carcinoma With the Help of Mcm-2: An Immunohistochemical Study.

Abstract

The knowledge of cellular proteins that involves cell cycle and its control system is essential for understanding tumor biology. Minichromosome maintenance protein (Mcm-2), a component of prereplicative complex, essential for initiating DNA replication, is deregulated in different malignant lesions, and is expressed throughout the whole cell cycle including the G0 and G1 phases. This characteristic cell cycle event is not found in other proliferative markers such as geminin, AgNOR, Ki-67, and proliferating cell nuclear antigen. The aim of the present study was to analyze and compare the expression of Mcm-2 in normal oral mucosa (NM) and oral squamous cell carcinomas at tumor margins (TM), the tumor center (TC), and the invasive tumor front (ITF), with correlation of clinicopathologic features. Tissues from 50 oral squamous cell carcinomas and 10 NM were archived retrospectively and stained with an antibody directed against the Mcm-2 antigen. A quantitative method was used to score the Mcm-2 expression in NM, TM, TC, and ITF. Nuclei labeling index for each case was estimated as the percentage of immunoreactive nuclei among 500 cells separately for NM, TM, TC, and ITF. Nuclei labeling index increases progressively from NM (49.08%), TM (67.79%), and TC (76.87%) to ITF (87.77%). Cell proliferation by Mcm-2 at the ITF had a strong positive relationship with TC, TM. Mcm-2, a pan-cell cycle marker, is more sensitive in comparison with other conventional proliferative markers, which can be a better prognostic indicator.