Synthesis and expression of CDw75 antigen in human colorectal cancer.
BACKGROUND
Increased ST6Gal I activity has been associated with the alpha(2,6)sialylation enhancement of membrane glycoconjugates observed in metastatic colorectal carcinomas (CRC). Siaalpha(2,6)Galbeta(1,4)GlcNAc sequence, known as CDw75, is a sialylated carbohydrate determinant generated by the ST6Gal I. This epitope has been reported to be associated with the progression of gastric and colorectal tumours, hence there are only a few conclusive studies to date.


METHODS
By radioisotopic techniques we evaluated the ST6Gal I activity in healthy, transitional and tumour tissues from 43 patients with CRC. By immunohistochemistry we assessed the CDw75 expression in 25 colorectal adenomas, 43 tumours, 13 transitional and 28 healthy tissues of CRC patients.


RESULTS
ST6Gal I activity was likewise found to be statistically higher in tumour tissue respect to healthy tissue from CRC patients. CDw75 expression was positive in 20% of colorectal adenomas. Furthermore, 70% of tumour specimens and 8.3% of transitional specimens were positive for CDw75 expression, whereas none of the healthy ones showed the presence of the epitope.


CONCLUSIONS
The major contribution of this study is the inclusion of data from transitional tissue and the analysis of CDw75 antigen expression in CRC and in colorectal adenomas, little known so far. ST6Gal I activity and CDw75 antigen expression were increased in CRC. Although their comparison did not reach the statistical significance, a great extent of patients showed both, an enhanced tumour ST6Gal I activity and an increased CDw75 expression in the tumour tissue. So, these two variables may play a role in malignant transformation. The expression of CDw75 in colorectal adenomas suggests that this antigen may be a tumour marker in CRC.
Costa-Nogueira
Clotilde
C
Department of Biochemistry, Genetics and Immunology, Faculty of Biology, University of Vigo, Vigo, Spain. cloticn@yahoo.es
Villar-Portela
Susana
S
Cuevas
Elisa
E
Gil-Martín
Emilio
E
Fernández-Briera
Almudena
A
D000230:Adenocarcinoma / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D000236:Adenoma / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D000368:Aged; D015703:Antigens, CD / Q000096:biosynthesis* / Q000378:metabolism*; D014408:Biomarkers, Tumor / Q000032:analysis*; D015179:Colorectal Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D018450:Disease Progression; D015870:Gene Expression; D006801:Humans; D007150:Immunohistochemistry; D009367:Neoplasm Staging; D012799:Sialyltransferases / Q000096:biosynthesis* / Q000378:metabolism*; D000094802:beta-D-Galactoside alpha 2-6-Sialyltransferase
D015703:Antigens, CD; D014408:Biomarkers, Tumor; D012799:Sialyltransferases; C093493:ST6GAL1 protein, human; D000094802:beta-D-Galactoside alpha 2-6-Sialyltransferase