Isolation and characterization of glycoconjugates from B16 mouse melanoma tumors

The major glycosaminoglycans isolated from B16 mouse melanoma tumors after Pronase digestion were shown to be a family of chondroitin 4-sulfates with different degrees of sulfation and a wide molecular-weight range. Ultracentrifugation data gave molecular weight values as high as 88 000, in contrast to that of costal cartilage chondroitin 4-sulfate which is about 14 000. A mucin-type sialoglycopeptide, isolated from the tumors by cetylpyridinium chloride precipitation of the Pronase digest, was shown to contain O-glycosylically linked tetra- and tri-saccharides consisting of sialic acid, galactose, and N-acetylgalactosamine. The sialoglycoprotein, which on Pronase digestion gave rise to the glycopeptide, was isolated from the tumor by extraction with lithium diiodosalicylate and affinity chromatography on a wheat-germ agglutinin-Sepharose 4B column. It was homogeneous on the basis of gel filtration on Sepharose 4B and Sephadex G-200 columns, lectin affinity, and ion-exchange chromatography. The compounds isolated from the B16 mouse melanoma tumors are similar to those produced by the cultured melanoma cells, which suggests that the latter compounds are not artifacts of the culture system.