shRNA library screening identifies nucleocytoplasmic transport as a mediator of BCR-ABL1 kinase-independent resistance
Menée sur des lignées cellulaires de leucémie myéloïde chronique, cette étude met en évidence le rôle joué par deux composants du complexe de transport nucléo-cytoplasmique, RAN et XPO1, dans la résistance à l'imatinib indépendamment de l'activité tyrosine kinase de BCR-ABL1
The mechanisms underlying tyrosine kinase inhibitor (TKI) resistance in chronic myeloid leukemia (CML) patients lacking explanatory BCR-ABL1 kinase domain mutations are incompletely understood. To identify mechanisms of TKI resistance that are independent of BCR-ABL1 kinase activity, we introduced a lentiviral shRNA library targeting ~5,000 cell signaling genes into K562R, a CML cell line with BCR-ABL1 kinase-independent TKI resistance expressing exclusively native BCR-ABL1. A customized algorithm identified genes whose shRNA-mediated knockdown markedly impaired growth of K562R cells compared to TKI-sensitive controls. Among the top candidates were two components of the nucleocytoplasmic transport complex, RAN and XPO1 (CRM1). shRNA-mediated RAN inhibition or treatment of cells with the XPO1 inhibitor, KPT-330 (SelinexorTM), increased the imatinib sensitivity of CML cell lines with kinase-independent TKI resistance. Inhibition of either RAN or XPO1 impaired colony formation of CD34+ cells from newly diagnosed and TKI-resistant CML patients in the presence of imatinib, without effects on CD34+ cells from normal cord blood or from a patient harboring the BCR-ABL1T315I mutant. These data implicate RAN in BCR-ABL1 kinase-independent imatinib resistance, and show that shRNA library screens are useful to identify alternative pathways critical to drug resistance in CML.