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The present study aimed to determine significance of E-cadherin, a cell adhesion molecule, and sialyl Lewis-X (sLeX), a cell surface antigen, in oral carcinogenesis. Expressions of E-cadherin and sLeX were detected using western blot analysis from oral malignant (n=25), and oral precancerous tissues (OPC, n=20) and their adjacent normal tissues. An altered expression of E-cadherin (E-cad) and sLeX was observed in malignant and precancerous tissues. E-cad western blot revealed presence of two bands, a 120 kDa (native, E-cad120) and a 97 kDa (known as truncated E-cad97). The accumulation of truncated E-cad97 and sLeX in malignant and OPC tissues compared to their adjacent normal tissues was observed. Receiver's Operating Characteristics (ROC) curve analysis showed good discriminatory efficacy of E-cad97, E-cad97:120 ratio and sLeX between the malignant and adjacent. normal tissues. Further, a positive correlation of E-cad97 and sLeX overexpression with advanced stage of the disease and lymphnode metastasis was observed. The data suggest that E-cadherin truncation and sLeX overexpression are early events which may facilitate the tumor cells to metastasize. Also, overexpression E-cad97 and sLeX in OPC tissues may be useful to predict metastatic potentials of tumors at an early stage of oral carcinogenesis. Key words: Oral cancer, oral precancerous conditions, E-cadherin, sialyl Lewis-X, metastasis.

Purpose: To assess the role of biomarker levels in predicting radiotherapy (RT) response in patients with squamous cell carcinoma of buccal mucosa treated with postoperative RT., Materials and Methods: Thirty-one patients with squamous cell carcinoma of buccal mucosa who received postoperative RT were enrolled for the study. Glutathione S-transferase (GST), glutathione reductase (GR), superoxide dismutase (SOD) and catalase activity were analysed from primary tumour and adjacent normal mucosa of the same patients before RT. p53 and p21ras were localized immunohistochemically., Results: Enzyme activation was predicted by comparing the levels of these enzymes in tumour and adjacent normal mucosa. Deactivation of GST, activation of GR, SOD and catalase were associated with poor response to RT. p53 immunoreactivity was associated with failure to respond to RT., Conclusions: These markers may be useful in predicting treatment outcome in patients receiving postoperative RT, although this conclusion requires confirmation in a larger group of patients.