Expression Data form parental vs. TAE684 resistant SH-SY5Y neuroblastoma cells

The crizotinib–resistant ALKF1174L mutation arises de novo in neuroblastoma (NB) and is acquired in ALK translocation-driven cancers, lending impetus to the development of novel ALK inhibitors with different modes of action. The diaminopyrimidine TAE684 and its derivative ceritinib (LDK378), which are structurally distinct from crizotinib, are active against NB cells expressing ALKF1174L. Here we demonstrate acquired resistance to TAE684 and LDK378 in ALKF1174L-driven human NB cells that is linked to overexpression and activation of the AXL tyrosine kinase and epithelial-to-mesenchymal transition (EMT). AXL phosphorylation conferred TAE684 resistance to NB cells through upregulated ERK signaling. Inhibition of AXL partly rescued TAE684 resistance, resensitizing these cells to this compound. AXL activation in resistant cells was mediated through increased expression of the active form of its ligand, GAS6, which also served to stabilize the AXL protein. Although ectopic expression of AXL and TWIST2 individually in TAE684-sensitive parental cells led to the elevated expression of mesenchymal markers and invasive capacity, only AXL overexpression induced resistance to TAE684 as well. TAE684-resistant cells showed greater sensitivity to HSP90 inhibition than did their parental counterparts, with downregulation of AXL and AXL-mediated ERK signaling. Our studies indicate that aberrant AXL signaling and development of an EMT phenotype underlie resistance of ALKF1174L-driven NB cells to TAE684 and its derivatives. We suggest that the combination of ALK and AXL or HSP90 inhibitors be considered to delay the emergence of such resistance. In order to understand the molecular mechanisms driving resistance to ALK inhibition in ALK-mutated neuroblatoma, we established cell line models of resistance to TAE684, an ALK inhibitor, by treating SH-SY5Y cells (bearing the ALKF1174L mutation) with increasing concentration of this compound over time. We then performed an analysis of gene expression changes genome wide using Affymetrix U133 Plus 2 arrays, by comparing the TAE684-sensitive parental SH-SY5Y cells to the TAE684-resistant SH-SY5Y cells (named SY5Y-TR1). For that experiment, we analyzed gene expression variations by comparing the parental SH-SY5Y (control sample) to the resistant SY5Y-TR1 cells. So 2 samples were analyzed, with 3 replicates run for each.