SELECTIVE REDUCTION OF 6-O-SULFATION IN HEPARAN-SULFATE FROM TRANSFORMED MAMMARY EPITHELIAL-CELLS

Heparan sulfate at cell surfaces and in the extracellular matrix regul ates cell proliferation and adhesion by binding to growth factors and matrix proteins via structurally specific oligosaccharide domains. We have used the hormonally regulated mouse mammary carcinoma cell line S 115 as a model to elucidate the effect of malignant transformation on the structure of heparan sulfate. When cultured in the presence of tes tosterone, S115 cells form tumor cell colonies in soft agar and exhibi t fibroblast-like morphology; withdrawal of testosterone results in a loss of the tumorigenic capacity and a switch towards epithelial morph ology. Metabolically (SO4)-S-35-labeled heparan sulfate was isolated f rom testosterone-treated and nontreated S115 cells and subjected to st ructural analysis. We found that the testosterone-dependent malignant transformation was associated with reduced sulfation of heparan sulfat e due to a approximately 40% decrease in the amount of GlcN6S units. B y contrast, no significant differences were observed in the amounts of 2-O-sulfate or N-sulfate groups. The reduced 6-O-sulfation of GlcN un its in heparan sulfate from transformed S115 cells led to a marked dec rease in the amount of trisulfated IdoA2S-GlcNS6S units (IdoA, L-iduro nic acid), implicated in many heparan sulfate-protein interactions.