The complexity of the complicity of mast cells in cancer.

Mast cells are evolutionarly ancient cells of the immune cells which can secrete a variety of effector molecules. Animal and pathologic studies suggest that mast cells may promote tumor growth in some cancer types but may act in an opposite manner in others. In several mouse models a critical role of mast cells for tumor promotion was demonstrated. In humans mast cells are dependent upon the tyrosine kinase receptor c-Kit. This receptor is inhibited by many of the new anti-cancer tyrosine kinase inhibitors including Pazopanib, Imatinib and Masitinib. These drugs probably ablate some tumor mast cells, in addition to their other known antitumor effects. Understanding the complex roles of mast cells in cancer should aid in understanding mechanisms of current tyrosine kinase inhibitors, and the development of innovative anti-cancer therapies.