Background. Pancreatic cancer has a poor prognosis, and early diagnosis of carcinoma and discrimination between malignant and benign conditions are difficult. Many pancreatic cancer‐associated antigens, such as CA 19‐9, DU‐PAN‐2, YPan‐1, and SPan‐1, have been studied. However, expression of Tn, sialosyl‐Tn, and T antigens in tissues of different types of pancreatic neoplasms has not been investigated systematically. Moreover, little is known about the distribution of different types of apomucins in the pancreas. Methods. The expression of Tn, sialosyl‐Tn, and T antigens and DF3 (mammary type apomucin) and intestinal MRP (intestinal type apomucin) was examined immunohistochemically in 47 pancreatic tumors: 36 invasive ductal carcinomas, 5 intraductal papillary tumors, and 6 adenomas. Results. In normal pancreatic tissues, neither Tn nor sialosyl‐Tn antigen was expressed. In contrast, expression of both Tn and sialosyl‐Tn antigens was observed in all the invasive ductal carcinomas and intraductal papillary tumors. None of the adenomas expressed both Tn and sialosyl‐Tn. DF3 antigen was expressed in all invasive ductal carcinomas but not in intraductal papillary tumors, whereas intestinal MRP was expressed in all the intraductal papillary tumors but not in the invasive ductal carcinomas. Conclusions. The results from this study suggest that the expression of the mucin core protein and mucin carbohydrate antigens is correlated with the biologic behavior of pancreatic tumors. In particular, the expression of mammary type mucin core protein and intestinal type mucin core protein showed a striking contrast between invasive ductal carcinomas with a poor prognosis and intraductal papillary tumors with a favorable prognosis.
Human colon cancer is associated with antigenic and structural changes in mucin-type carbohydrate chains (O-glycans). To elucidate the control of the biosynthesis of these O-glycans is colon cancer, we have studied glycosyltransferase and sulphotransferase activities involved in the assembly of elongated O-glycan structures. We analysed homogenates prepared from cancer tissue, adjacent normal and distal normal tissue from 20 patients. Several transferase activities showed pronounced changes in cancer tissue. The changes correlate with previous findings of a loss of O-glycans in cancer mucins, but did not always correlate with levels of Tn, sialyl-Tn, T and Lex antigens in homogenates or with the differentiation status and Duke's stages of the cancer tissue or the patient's blood type, sex and age. UDP-GlcNAc: Gal NAc-R beta 3-N-acetylglucosaminyltransferase (where GlcNAc is N-acetyl-D-glucosamine and GalNAc is N-acetyl-D-galactosamine) synthesizing O-glycan core 3, GlcNAc beta 1-3GalNAc-, CMP-sialic acid: GalNAc-peptide alpha 6-sialyltransferase synthesizing the sialyl-Tn antigen and sulphotransferase activities towards O-glycan core 1, Gal beta 1-3GalNAc-, were found to be decreased in cancer. UDP-GlcNAc: Gal beta 1-3GalNAc beta 6-N-acetylglucosaminyltransferase was also decreased in cancer concomitant with a loss of the ability to synthesize the I antigen and core 4, GlcNAc beta 1-6(GlcNAc beta 1-3) GalNAc-, CMP-sialic acid: Gal beta 1-3GalNAc-R alpha 3-sialyltransferase and GDP-fucose: Gal beta-R alpha 2-fucosyltransferase, synthesizing the blood group H determinant, were found to be 4- and 3- to 8-fold increased, respectively, in cancer compared to normal tissue. The data suggest that the biosynthesis of antigens and mucin-bound O-glycan structures in colon cancer is subject to complex control mechanisms.
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