Prognostic value of human telomerase reverse transcriptase gene expression in oral carcinogenesis.

Human telomerase reverse transcriptase (hTERT) gene expression in resected specimens of oral squamous cell carcinoma (OSCC) and their surrounding tissue, either apparently normal or clearly histologically dysplastic, was evaluated by both real-time RT-PCR and immunohisto-chemical protein analyses. The expression level of hTERT in oral dysplasia and in OSCC was markedly higher than in normal tissues. The correlation between hTERT expression in OSCC and clinico-pathological parameters or survival of OSCC patients was statistically analyzed. Our study demonstrates that there is no significant relationship between hTERT expression and classical clinico-pathological parameters. Interestingly, survival analysis showed both overexpressing cases and lower survival rate in the early stage of OSCC (p=0.03 for immunohistochemistry; p=0.04 for RT real-time PCR). The histological location of hTERT in these tumors has been discussed in the context of the cancer stem cell theory.

Survivin phosphorylation and M-phase promoting factor in oral carcinogenesis.

Survivin is a recently described inhibitor of apoptosis and mitotic regulator which is selectively over-expressed in human tumors. Its expression rate is predictive of disease progression, early recurrences and resistance to therapy. Up-regulation of survivin in oral pre-malignant lesions (OPL) and in oral squamous cell carcinoma (OSCC) has already been demonstrated in previous studies. A critical step for activation of survivin has been identified in the phosphorylation on Thr34 by the main mitotic kinase p34cdc2-cyclin B1. The aim of this work was to investigate the relationship between survivin, its phosphorylated active form (p-survivin) and M-phase promoting factor (MPF), p34cdc2-cyclin B1 in oral carcinogenesis. 32 OSCCs and 17 OPLs from surgical specimens were studied for cyclin B1, p-survivin, survivin, and p34cdc2 expression by immunohistochemistry. All cases of OSCC expressed survivin and its expression rate was correlated to p-survivin levels (P<0.05). Cyclin B1 was positive in 80% of cases, while p-34cdc2 was over-expressed in all OSCCs. All OPLs associated with OSCC expressed survivin and its levels were correlated to p-survivin levels (P<0.05). Cyclin B1 was positive in 70% of cases, while p-34cdc2 was positive in all OPLs. In conclusion, this study demonstrated that MPF, survivin and p-survivin are expressed during early and late phase of oral carcinogenesis. MPF proteins, which are co-expressed on mitotic apparatus, could represent a potential target for therapies based on manipulation of survivin phosphorylation, which would induce apoptosis in cancer cells.