Effects of glycosaminoglycans and extracellular matrix components on metastatic rat rhabdomyosarcoma tumor and myoblast cell proliferation.

Experiments were performed to determine the relative effects of glycosaminoglycans and extracellular matrix components alone or in association with various substrates, including extracellular matrix, on the proliferation of rat rhabdomyosarcoma (RMS) cell lines of different metastatic potential and nontumorigenic rat myoblast L6 cells. The assays used various substrates: tissue culture plastic, type I and IV collagen, fibronectin, laminin and extracellular matrix deposited by corneal endothelial cells. In control experiments, tumor cells grew faster on fibronectin and extracellular matrix than on the other substrates, and their proliferation rate was decreased slightly by laminin. Collagens were growth-inhibitory only for the highly metastatic line. The proliferation rate of L6 myoblasts was not greatly affected by the different substrates. The addition of exogenous glycosaminoglycans to the culture medium modified cell proliferation on the various substrates. Heparin inhibited the growth of all the cell lines tested, independent of the substrate. When cultured on laminin substrate the proliferation rates of the cell lines were depressed by addition of heparan sulfate to the medium, and this effect was more pronounced in the metastatic RMS lines. Chondroitin sulfate and dermatan sulfate enhanced the growth rates of the tumorigenic cells when cultured on collagen type I surfaces. Hydrocortisone, which induces myogenic differentiation, decreased the cell proliferation rates of all the cell lines tested and intensified the inhibitory effects of heparin when added simultaneously to the culture medium. The results showed that glycosaminoglycans and other matrix components can affect the proliferation rates of rhabdomyosarcoma cell lines.