Expression of hTERT in Oral Submucous Fibrosis and Oral Squamous Cell Carcinoma - an Immunohistochemical Analysis

Human telomerase reverse transcriptase enzyme, the catalytic subunit of telomerase are seen to be frequently reactivated in cancers including Oral squamous cell carcinoma (OSCC). Increased hTERT expression have been seen in potentially malignant conditions including Oral submucous fibrosis (OSMF). The aim of the study was to evaluate the expression levels in OSMF, OSCC in the background of OSMF and OSCC using immunohistochemistry and also to correlate hTERT expression with clinicopathologic parameters. A total of 50 histopathologically diagnosed cases of 20 OSMF, 20 OSCC wherein 5 were OSCC in the background of OSMF and 10 Normal oral mucosae were retrieved from the departmental archives and subjected to immunohistochemical analysis of hTERT. The expression of hTERT increased from normal, OSMF, to OSCC with statistically significant differences in mean labelling score (LS). We also found a shift in cellular localization of stain where, normal mucosal tissues showed a nuclear stain unlike OSMF, where combined nuclear and cytoplasmic staining as noted. The tumor cells in OSCC showed predominant cytoplasmic staining. There was no correlation between hTERT expression and clinicopathological parameters of OSMF. However, a significant increase of hTERT expression was seen with increasing histological grading of OSCC. These results suggest the role of hTERT in the early event of malignant transformation of OSMF. Telomerase could be used as a potent diagnostic marker to identify high-risk group of OSMF.