Inhibition of Mer and Axl receptor tyrosine kinases leads to increased apoptosis and improved chemosensitivity in human neuroblastoma

Ectopic expression of Mer and Axl receptor tyrosine kinases (RTKs) are frequently found in various cancers as known to promote oncogenesis by activating antiapoptotic signaling pathways. However, the roles of these receptors in neuroblastoma remain unclear. We found Mer and Axl was co-expressed in neuroblastoma patient samples and cell lines. Ligand-dependent Mer or Axl activation led to an increase in phosphorylated ERK1/2, AKT and FAK indicating roles for these RTKs in multiple oncogenic processes. Furthermore, Mer and Axl knockdown led to apoptosis and inhibition of migration as well as a significant increase in chemosensitivity in response to cisplatin and vincristine treatment. Taken together, our results demonstrated that inhibition of Mer and Axl improved apoptotic response and chemosensitivity in neuroblastoma, providing new insights into development of novel therapeutic strategies by targeting these oncogenes.