Expression of UDP-N-Acetyl-α-d-Galactosamine-Polypeptide N-Acetylgalactosaminyltransferase Isozyme 3 in the Subserosal Layer Correlates with Postsurgical Survival of Pathological Tumor Stage 2 Carcinoma of the Gallbladder

Purpose and Experimental Design: Little is known about the molecular events leading to the development and progression of pathological tumor stage 2 (pT 2 ) gallbladder carcinoma. An alteration in the site of O -glycosylation may be associated with malignant behavior of carcinoma cells by modulation of the biological properties of the target mucin. The UDP- N -acetyl-α- d -galactosamine-polypeptide N -acetylgalactosaminyltransferase isozyme 3 (GalNAc-T3) has the epithelial gland-specific expression and catalyzes mucin-type O -glycosylation. In this study, immunohistochemistry was performed to determine the expression level of GalNAc-T3 in 34 cases of pT 2 gallbladder carcinoma to determine the correlation of the GalNAc-T3 expression level with mode of recurrence and postsurgical survival. Results: The expression levels of GalNAc-T3 protein and mRNA were increased in gallbladder carcinomas compared with the levels in adjacent noncancerous tissues and in intact gallbladders. Immunostaining of GalNAc-T3 was recognized in the cancerous epithelia, and the subcellular localization was classified into granular and diffuse types. In the 34 cases of pT 2 carcinoma, the localization of GalNAc-T3 was granular type in 50% and diffuse type in 50% of the cases at the deepest invading sites in the subserosal layer. Postsurgical recurrence was significantly more frequent in cases showing diffuse-type localization of GalNAc-T3 at the deepest invading sites (65%) than in those showing granular-type localization (23%; P < 0.05). Postsurgical survival was significantly poorer in cases showing diffuse-type localization than in those showing granular-type localization ( P = 0.033) Conclusions: In pT 2 gallbladder carcinoma, the presence of diffuse-type localization of GalNAc-T3 in the subserosal layer is correlated with aggressiveness of the disease. This phenotype may serve as a unique biological feature associated with the malignant behavior.