O-glycosylation in Echinococcus granulosus: identification and characterization of the carcinoma-associated Tn antigen.
In the present work we demonstrate that the cancer-associated O-glycosylated Tn antigen (GalNAc-O-Ser/Thr) is expressed by the cestode Echinococcus granulosus. This antigen was detected in both larval and adult worm extracts, with the highest specific activity observed in the adult excretion/secretion preparation. Histochemical analysis showed that Tn is preferentially expressed in the parenchyma in both parasite stages and the external part of tegument in adult worms. A similar pattern was observed for sialyl-Tn, a related O-linked antigen. Tn glycoproteins from protoscoleces were resolved by SDS-PAGE in two main components of 43 and 49 kDa. After purification, this material was reactive with lectins which bind GlcNAc/sialic acid, GalNAc, and T antigen. In a preliminary evaluation, high levels of Tn antigen were detected in serum samples from patients with hydatid cyst, suggesting that the measure of Tn in serum could be a biomarker of this disease, although extensive work is necessary in order to determine the clinical usefulness of this assay. The results reported here, the first evidence of O-glycosylation pathways in E. granulosus and the presence of Tn antigen in cestodes, suggest that the evaluation of O-glycosylated antigens might give new insights in the host-parasite relationship.
Alvarez Errico
D
D
Depto. de Bioquímica, Facultad de Medicina, Montevideo, Uruguay.
Medeiros
A
A
Míguez
M
M
Casaravilla
C
C
Malgor
R
R
Carmona
C
C
Nieto
A
A
Osinaga
E
E
D000328:Adult; D000818:Animals; D015295:Antigens, Tumor-Associated, Carbohydrate / Q000097:blood / Q000302:isolation & purification* / Q000378:metabolism; D015153:Blotting, Western; D001943:Breast Neoplasms / Q000097:blood / Q000276:immunology; D002846:Chromatography, Affinity; D004285:Dogs; D004443:Echinococcosis / Q000097:blood / Q000276:immunology*; D004446:Echinococcus / Q000276:immunology* / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005455:Fluorescent Antibody Technique; D006031:Glycosylation; D006801:Humans; D037102:Lectins / Q000378:metabolism; D008297:Male
D015295:Antigens, Tumor-Associated, Carbohydrate; D037102:Lectins; C040286:Tn antigen