Cross-talks between c-Kit and PKC isoforms in HMC-1560 and HMC-1560,816 cells. Different role of PKCδ in each cellular line

The c-kit inhibitor STI571 represents one of the most important treatments for patients with mastocytosis. However, intracellular pathways modulated by this compound are not completely defined. Here, STI571 effect on Protein Kinase C (PKC) regulation is determined in HMC-1 mast cell lines. STI571 activates PKCδ isoform resulting in HMC-1560 apoptosis. The apoptosis observed is PKCδ-dependent, since PKCδ-silencing avoids STI571 effect. c-kit inhibition implies nuclear PKCδ translocation characterized by a clear dependence on actin cytoskeleton integrity in HMC-1560 cell line, but not in HMC-1560,816. Therefore, PKCδ modulations can lead to a serious decrease in STI571 treatment-effectiveness.