Correlation analysis between tumorous associated antigen Sialyl-Tn expression and ST6GalNAc I activity in human colon adenocarcinoma

Objectives: Sialyl-Tn (sTn) is a mucin carbohydrate-associated antigen that is strongly expressed in a large number of colorectal carcinomas. In this study, we combined immunohistochemical and enzymatic techniques in order to find the correlation between sTn tissue expression and the sialyltransferase activity (ST6GalNAc I) responsible for its synthesis in colorectal cancer (CRC) patients. Methods: We compared sTn expression in healthy (n = 46), tumorous (n = 60) and transitional tissue (n = 46) from CRC patients, and correlated sTn altered expression with clinicopathologic variables of the patient. Furthermore, we determined ST6GalNAc I tissue activity employing asialo-ovine submaxillary mucin (asialo-OSM) as glycoprotein acceptor (n = 27). Results: The rates of sTn positive expression obtained for healthy, tumorous and transitional tissues were 15, 67 and 63%, respectively. These rates led to statistically significant differences between healthy and tumorous or transitional tissue (p = 0.001); sTn expression was related to the first stages of the tumor invasion in transitional tissue. As regards ST6GalNAc I activity, we found an enhancement in transitional tissue. Statistical correlation analysis did not reveal association between sTn expression and ST6GalNAc I activity. Conclusions: Our findings indicated that sTn antigen tissue expression and ST6GalNAc I activity levels were not correlated in CRC, in spite of the overexpression of the antigen in tumorous and transitional tissue. Copyright (C) 2004 S. Karger AG, Basel.