sLea and sLex expression in colorectal cancer: implications for tumourigenesis and disease prognosis

Abstract

The glycoconjugates expressed by cancer cells frequently contain sialylated oligosaccharide chains. Among these oligosaccharides the sialyl Lewis a (sLea) and sialyl Lewis x (sLex) antigens are found to be overexpressed in tumours of different origin. The current study assesses sLea and sLex expression in different colorectal specimens in order to establish the correlation of these biomarkers with both malignant transformation of colorectal mucosa and the progression of colorectal cancer (CRC). Healthy disease-free and inflammatory mucosa specimens showed no presence of the antigens. sLea was expressed in 6.7% of the healthy tissue from CRC patients, in 20.8% of the adenomas, and in 33.3% and 42.6% of the transitional tissue and tumour tissue, respectively. sLex expression was observed in 6.7% of the healthy tissue from CRC patients, in 27.0% of the adenomas, and in 25.6% and 74.8% of the transitional and the tumour tissue, respectively. The expression of the sLea and sLex antigens was correlated in adenomas, as well as in healthy and tumour tissue from CRC. Moreover, the high expression of sLex in adenomas was correlated with a high degree of dysplasia (p=0.042). Finally, the survival analysis suggested that sLea expression may be a prognostic factor for predicting disease-free survival in colorectal cancer (p=0.012).