Gene expression profiling of imatinib and PD166326-resistant CML cell lines identifies Fyn as a gene associated with resistance to BCR-ABL inhibitors

Abstract

Imatinib is used to treat chronic myelogenous leukemia (CML), but resistance develops in all phases of this disease. The purpose of the present study was to identify the mode of resistance of newly derived imatinib-resistant (IM-R) and PD166326-resistant (PD-R) CML cells. IM-R and PD-R clones exhibited an increase in viability and a decrease in caspase activation in response to various doses of imatinib and PD166326, respectively, as compared with parental K562 cells. Resistance involved neither mutations in BCR-ABL nor increased BCR-ABL, MDR1 or Lyn expression, all known modes of resistance. To gain insight into the resistance mechanisms, we used pangenomic microarrays and identified 281 genes modulated in parental versus IM-R and PD-R cells. The gene signature was similar for IM-R and PD-R cells, accordingly with the crosssensitivity observed for both inhibitors. These genes were functionally associated with pathways linked to development, cell adhesion, cell growth, and the JAK-STAT cascade. Especially relevant were the increased expression of the tyrosine kinases AXL and Fyn as well as CD44 and HMGA2. Small interfering RNA experiments and pharmacologic approaches identified FYN as a candidate for resistance to imatinib. Our findings provide a comprehensive picture of the transcriptional events associated with imatinib and PD166326 resistance and identify Fyn as a new potential target for therapeutic intervention in CML.

Mechanism of action of the multikinase inhibitor Foretinib

“…We investigated here the effect of Foretinib on IM-S and IM-R K562 CML cells, because we previously reported that IM-R cells overexpressed AXL as a potential mechanism of resistance to this drug. 8 Foretinib inhibited the growth of both IM-S and IM-R cells in the 30-1000 nM range. The effect of the drug on cell number was found to be maximal at 72 h but significant decrease in cell count was already detected at 24 h (Fig.…”

“…[12][13][14]16 We recently generated Imatinib-resistant CML cell lines that display increased expression of AXL at the mRNA and protein levels. 8 To investigate the potential role of Axl in the resistance of IM-R cells to Imatinib we used Foretinib in an attempt to inhibit Axlmediated signaling. However, Foretinib was found to inhibit to the same extent the proliferation and clonogenic potential of IM-R cells and those of its Imatinib-sensitive counterparts.…”

“…Importantly, activation of tyrosine kinases, including LYN, FYN and AXL, has been reported in IM-resistant cell lines and also in CML patients treated with such inhibitors. 8,9 Therefore, targeting TK whose expression is increased in resistant patients may represent a promising strategy to cure the significant proportion of patients refractory to the TKI currently used in clinic.…”

CD44 in hematological neoplasias

“…Instead CD44 and Fyn are upregulated in these cells and knock down or inhibition of Fyn results in re-sensitization to Imatinib [151]. Because of known CD44/Fyn association [53], the role of CD44 in this process has to be elucidated further.…”

Screen and analysis of key disease genes for precancerous lesions of oral buccal mucosa induced by DMBA in golden hamsters

“…Lyn, Btk, Hck and Fes are members of the non-receptor-type PTK family. A high expression of Lyn, Btk, Hck and Fes results in cell proliferation, anti-apoptosis and the promotion of angiogenesis (34)(35)(36). Up-regulation of Vav1 and IL5ra is correlated to tyrosine phosphorylation and the activation of signal transduction.…”