Macropinocytosis in Melanoma Cells: The Effects of Amiloride and Hyaluronate

Shane Swink 

Advisor:  Dr. Ralph SorensenShane Swink

Endocytosis is the process by which cells are able to obtain nutrients from their external environment, cleanup cellular debris, down-regulate surface receptors, and uptake pathogens in immune responses.  Metastatic (secondary) cancer cells, in contrast to primary cancer cells, cannibalize brother cancer cells for nutrition. It is unclear what method of endocytosis is employed by cancer cells to engulf brother cells. One possible endocytic process is macropinocytosis, a non-specific, bulk uptake of extracellular fluid and its contents. Amiloride is a specific inhibitor of macropinocytosis. In contrast, hyaluronate has been shown to stimulate macropinocytosis. Experiments were conducted to measuring the kinetics of fluorescent polystyrene bead uptake in B16-F10 murine melanoma cells. This process was inhibited by amiloride and stimulated by hyaluronate in a dose-dependent manner suggesting that polystyrene beads, and, by extension, brother cancer cells, are taken up by melanoma cells using the process of macropinocytosis.