Modulation of the lung colonization of B16-F1 melanoma cells by citrus pectin.
BACKGROUND
Studies have shown that the galactoside-containing simple sugars and anti-galactoside-binding lectin antibodies may affect experimental tumor cell metastasis. However, the limited number of reagents used thus far necessitate further observations.


OBJECTIVE
Natural citrus pectin (CP) and pH-modified CP (MCP), rich in galactose residues, were used to study the involvement of carbohydrates containing galactoside residues in cellular interaction in vitro and in lung colonization in vivo of B16-F1 melanoma cells.


METHODS
B16-F1 melanoma cells were incubated with various concentrations of CP and MCP. Their ability to form homotypic aggregation in vitro and tumor lung colonization in vivo in 8-week-old female C57BL/6 mice was then analyzed.


RESULTS
The CP binds to the surface of B16-F1 melanoma cells; this binding can be inhibited by lactose at a concentration of 0.15 M. Intravenous injection of the murine B16-F1 melanoma cells with the natural CP resulted in a significant increase (up to threefold) in the appearance of tumor colonies in the lung and in increased homotypic aggregation properties of the cells, while injection of MCP significantly decreased B16-F1 experimental metastasis (greater than 90%).


CONCLUSIONS
Tumor galactoside-binding proteins mediate cellular recognition by linking oligosaccharides with terminal D-galactoside residues on adjacent cells. Successful interference with such a process with MCP may lead to a reduced ability to form tumor cell emboli and metastasis.


CONCLUSIONS
These findings imply that the galactose-containing carbohydrate side chains of CP might mimic or compete with the natural ligand(s) of the tumor galactoside-binding protein (gal-lectin) and thus affect cellular interactions relevant for metastasis.
Platt
D
D
Cancer Metastasis Program, Michigan Cancer Foundation, Detroit 48201-1379.
Raz
A
A
D000818:Animals; D002449:Cell Aggregation / Q000187:drug effects; D005260:Female; D008175:Lung Neoplasms / Q000556:secondary*; D008546:Melanoma, Experimental / Q000556:secondary*; D051379:Mice; D008810:Mice, Inbred C57BL; D009368:Neoplasm Transplantation; D010368:Pectins / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
D010368:Pectins