Polysaccharides of metaplastic mucosa and carcinoma of the gallbladder.

The polysaccharide composition of the human gallbladder well was studied in carcinomas and metaplastic changes of various degrees, and the results obtained were compared with those for the normal material previously presented (Terho, T., and Laitio, M. Biochim. Biophys. Acta 338: 135, 1974). Elevated amounts of acid connective tissue polysaccharides (heparitin and dermatan sulfates as well as chondroitin 4- or 6-sulfate, or both, could be observed in carinomas. In histochemical stainings it was found that in carcinomas and in the two specimens classified as group III (containing the most extensive metaplastic changes at disposal), the intracellular mucin was mainly neutral or nonsulfated acidic. The amounts of sulfated mucin were relatively insignificant. This mucin polysaccharide material was isolated and its composition was determined. It was observed to be large polysaccharide material was isolated and its composition was determined. It was observed to be large molecular (approximate molecular sizes 1 to 2 times 10-6), and to be composed of fucose, galactose, glucosamine, and galactosamine as well as small amounts of sialic acid. The basic structure of these polysaccharides is thus similar to that of normal sulfated mucin. The almost total absence of acid groups, however, causes the polysaccharide material in question to stain in a manner identical with neutral mucin when investigated with histochemical methods. The carcinomas also contained some sulfomucin; its proportion, however, was small as compared with the amounts of nonsulfated acid and neutral mucin in biochemical characterization. A small molecular polysaccharide fraction, assumed to originate in membrane-bound glycoproteins, was isolated from the insoluble gallbladder tissue residue. The proportion of this fraction was larger in carcinomas than in normal material. This rise as well as the rise in the quantity of acid connective tissue polysaccharides is presumably due to the large number of cells in the carcinoma tissue as well as to fibrosis.