Hexosamine-containing macromolecules in human colon carcinomas

Normal, transitional, and carcinoma areas of five colons resected for carcinoma were examined morphologically, histochemically, and biochemically. The transitional area contained a larger amount of non-sulphated acid mucin than the normal mucosa as verified histochemically. Normal mucosa contained mainly sulphated mucin. The hexosamine-containing macromolecules present in different areas were isolated and characterized. They were divided into the following groups: 1) acid glycosaminoglycans, 2) high-molecular-weight glycopeptides, and 3) low-molecular weight glycopeptides. The concentration of the total hexosamine-containing material was in the carcinoma area twice as high as in normal areas. Acid glycosaminoglycans were identified as hyaluronate, heparan sulphate, dermatan sulphate, and chondroitin 4-(6)-sulphate. Their concentraitons were found to increase from normal to transitional and from transitional to carcinoma areas. The high-molecular-weight glycopeptide was composed of fucose, galactose, glucosamine, galactosamine, sialic acid, and variable amounts of sulphate. The sulphation degree of the glycopeptide was higher in normal mucosa than in transitional or carcinoma areas: The low-molecular-weight glycopeptides consisted of about a half of the total hexosamine-containing substances. The concentration of saline-insoluble fraction of the low-molecular-weight glycopeptides was in transitional areas about two times, and in carcinoma areas about four times, higher than in normal mucosa.