Clinical Correlations of α2,6-Sialyltransferase Expression in Colorectal Cancer Patients

We have previously demonstrated a link between α2,6-Sialyltransferase (α2,6-ST; E.C. 2.4.99.1) expression and differentiation of colon tumors. So far, information is not available relative to the expression of α2,6-ST in tumors and the survival of patients with colorectal cancer. We have examined the expression of α2,6-ST in a variety of colorectal adenocarcinomas (n = 46) at different stages of differentiation (G₁ to G₃) by immunoperoxidase assay using monoclonal antibody (MAb) 6B9. Clinical outcome of the patients in a 5-year follow-up study has been correlated with the expression of α2,6-ST in tumors surgically removed from the same patients. No significant difference in the α2,6-ST expression was noted when age, sex, and tumor locations (colon, rectum) were included as parameters. However, 52% of the moderate (G₂) and well-differentiated (G₁) adenocarcinomas showed stronger α2,6-ST expression compared with poorly differentiated (G₃) adenocarcinomas. Notably, absence to moderate levels of tumor α2,6-ST expression was correlated with 100% survival in patients with stage I and II tumors compared with 64% survival in patients with strong tumor α2,6-ST expression (p < 0.01). These studies suggest a negative correlation between the expression of α 2,6-ST in tumors and a good clinical outcome in colorectal cancer patients.