| Abstract: | Glycosaminoglycan (GAG) synthesis of B-16 melanoma metastatic variants was examined in vivo and in vitro to begin to assess the relationship between the presence of these polymers and the process of primary invasion and metastasis. The variants that were examined for GAG production included the F-1 line that exhibits low metastatic potential, the F-10 line selected for high metastatic potential, and the BL6 line selected for high invasiveness. The F-1 cell line was routinely less invasive than the F-10 and BL6 lines when injected s.c. into the legs of irradiated Swiss Webster mice. All cell lines formed palpable tumors after s.c. injection, but histological sections revealed early and extensive invasion in only F-10 and BL6 tumors. The F-1 tumors were surrounded by a connective tissue capsule and did not begin to invade into host tissue until this structure disappeared approximately 16 days after injection of tumor cells. Some consistent alterations in GAG synthesis, particularly the release of hyaluronic acid and heparan sulfate, were observed among the cell lines in vivo and in vitro, although differences observed in vitro were small and variable. In vivo all tumors were surrounded by a hyaluronic acid-rich zone that was concentrated at the tumor-stromal interface and was transitory. Hyaluronate occurred as a diffuse band around BL6 and F-10 tumors but was confined to a capsule surrounding the less aggressive F-1 tumor. In vitro the BL6 and F-10 cell lines released larger amounts of heparan sulfate and hyaluronic acid than did the F-1 cell line. Differences in release of chondroitin sulfate by the cell lines were not observed. Differences in trypsin-releasable GAG, presumably associated with the glycocalyx, were also not apparent. These results link the release in vitro and organization in vivo of hyaluronic acid and heparan sulfate to invasion and metastasis. |
