Glycosaminoglycan production by murine melanoma variants in vivo and in vitro
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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.
Insights
Investigating glycosaminoglycan (GAG) synthesis in B-16 melanoma variants reveals that hyaluronic acid and heparan sulfate release are linked to tumor invasion and metastasis. Higher levels correlate with increased metastatic potential.
Area of Science:
- Oncology
- Biochemistry
- Cell Biology
Background:
- Metastasis is a complex process involving primary tumor invasion and spread.
- Glycosaminoglycans (GAGs) are crucial components of the extracellular matrix and cell surface, potentially influencing tumor behavior.
- B-16 melanoma variants with differing metastatic potentials provide a model to study GAG involvement in cancer progression.
Purpose of the Study:
- To investigate the relationship between glycosaminoglycan (GAG) synthesis and the invasive and metastatic capabilities of B-16 melanoma variants.
- To compare GAG production in vitro and in vivo among low (F-1) and high (F-10, BL6) metastatic/invasive B-16 melanoma cell lines.
- To determine if specific GAG alterations correlate with primary invasion and metastasis.
Main Methods:
- In vivo studies involved subcutaneous injection of B-16 melanoma variants into mice and histological analysis of tumor invasion.
- In vitro studies assessed GAG release by different melanoma cell lines.
- Quantification of released GAGs, including hyaluronic acid, heparan sulfate, and chondroitin sulfate, was performed.
Main Results:
- High metastatic variants (F-10, BL6) exhibited early and extensive invasion compared to low metastatic variant (F-1) in vivo.
- A hyaluronic acid-rich zone was observed around tumors in vivo, with a diffuse distribution in highly invasive tumors and a capsule in less invasive ones.
- In vitro, high metastatic/invasive cell lines released significantly more heparan sulfate and hyaluronic acid than the low metastatic cell line.
Conclusions:
- The synthesis and release of hyaluronic acid and heparan sulfate are linked to the invasive and metastatic potential of B-16 melanoma cells.
- The organization of hyaluronic acid in vivo, specifically its distribution at the tumor-stromal interface, correlates with metastatic behavior.
- These findings highlight the role of specific GAGs in mediating tumor invasion and metastasis.