Heparanases and tumor metastasis

Area of Science:

• Biochemistry
• Oncology
• Cell Biology

Background:

• Hematogenous tumor metastasis involves penetrating endothelial basement membranes.
• Heparan sulfate (HS) proteoglycan is a key component of these membranes.
• HS-degradative activities in metastatic melanoma correlate with lung colonization potential.

Purpose of the Study:

• To investigate the role of HS-degrading enzymes, specifically heparanase, in melanoma metastasis.
• To determine if heparanase activity is a viable target for metastasis inhibition.
• To assess heparanase as a potential marker for tumor metastasis.

Main Methods:

• Analyzing HS-degradative activities of B16 melanoma sublines.
• Identifying and characterizing the melanoma HS-degrading enzyme as heparanase (endo-beta-D-glucuronidase).
• Treating B16 melanoma cells with heparanase inhibitors (e.g., N-acetylated N-desulfated heparin) and assessing lung metastasis in mice.
• Measuring serum heparanase levels in tumor-bearing animals and melanoma patients.

Main Results:

• Melanoma heparanase is a unique endo-beta-D-glucuronidase cleaving HS at specific sites.
• Heparanase inhibitors significantly reduced experimental lung metastases in mice.
• Elevated serum heparanase levels correlate with the extent of metastasis in animals and humans.
• Heparanase is distinct from platelet and mastocytoma endoglucuronidases.

Conclusions:

• Heparanase plays a significant role in melanoma metastasis.
• Targeting heparanase with inhibitors shows promise for reducing tumor spread.
• Serum heparanase activity may serve as a useful biomarker for tumor metastasis.