Caspase-3 expression in normal oral epithelium, oral submucous fibrosis and oral squamous cell carcinoma

CONTEXT The epithelium atrophy, as the oral submucous fibrosis (OSMF) progresses, is believed to be an after effect of stromal fibrosis, hyalinization, decrease in vascularity and cellularity and is considered as "ischemic atrophy." Due to hypoxia, caspase-3 get activation and subsequent decrease in viable cell count can occur. AIMS AND OBJECTIVES To determine caspase-3 expression in various grades of OSMF and oral squamous cell carcinoma (OSCC) to find out whether upregulation of apoptosis is responsible for the epithelial changes in OSMF. SUBJECTS AND METHODS The control tissue (15 samples from normal oral mucosa) and study group comprising 97 cases of OSMF of different grades and OSCC associated with OSMF were stained with caspase-3 antibody, and the percentage of positive cells was calculated using ImageJ software. STATISTICAL ANALYSIS The results obtained were statistically analyzed using ANOVA and Tukey's honest significance difference test and Mann-Whitney U-test. RESULTS There was a nuclear expression of caspase-3 in basal and parabasal layers of normal epithelium. There was cytoplasmic expression of caspase-3 in OSMF without dysplasia, total absence of caspase-3 expression in dysplastic epithelium and in majority cases of OSCC. The caspase-3 percentage was increased in OSMF (0%-53%) when compared with OSCC (0%-8%). The statistical comparison of caspase-3 among normal, OSMF and OSCC patients revealed significant correlation (P < 0.00010). The comparison within different grades of OSMF and between dysplastic and nondysplastic epithelium OSMF also showed significance (P < 0.019). CONCLUSIONS The decreased expression of caspase-3 in disease progression reflects its role in the malignant transformation.