Gioia Romain, Trégoat Claire, Dumas Pierre-Yves, Lagarde Valérie, Prouzet-Mauléon Valérie, Desplat Vanessa, Sirvent Audrey, Praloran Vincent, Lippert Eric, Villacreces Arnaud, Leconet Wilhem, Robert Bruno, Vigon Isabelle, Roche Serge, Mahon François-Xavier, Pasquet Jean-Max
Hématopoïèse Leucémique et Cibles Thérapeutiques, INSERM U1035, Université de Bordeaux, France.
CNRS UMR5237, Centre de Recherche de Biochimie Macromoléculaire, Montpellier, France.
J Pathol. 2015 Sep;237(1):14-24. doi: 10.1002/path.4561. Epub 2015 Jun 4.
A tyrosine kinase network composed of the TAM receptor AXL and the cytoplasmic kinases LYN and SYK is involved in nilotinib-resistance of chronic myeloid leukaemia (CML) cells. Here, we show that the E3-ubiquitin ligase CBL down-regulation occurring during prolonged drug treatment plays a critical role in this process. Depletion of CBL in K562 cells increases AXL and LYN protein levels, promoting cell resistance to nilotinib. Conversely, forced expression of CBL in nilotinib-resistant K562 cells (K562-rn) dramatically reduces AXL and LYN expression and resensitizes K562-rn cells to nilotinib. A similar mechanism was found to operate in primary CML CD34(+) cells. Mechanistically, the E3-ligase CBL counteracts AXL/SYK signalling, promoting LYN transcription by controlling AXL protein stability. Surprisingly, the role of AXL in resistance was independent of its ligand GAS6 binding and its TK activity, in accordance with a scaffold activity for this receptor being involved in this cellular process. Collectively, our results demonstrate a pivotal role for CBL in the control of a tyrosine kinase network mediating resistance to nilotinib treatment in CML cells.
由TAM受体AXL以及胞质激酶LYN和SYK组成的酪氨酸激酶网络参与慢性髓性白血病（CML）细胞对尼洛替尼的耐药过程。在此，我们表明在长期药物治疗期间发生的E3泛素连接酶CBL下调在这一过程中起关键作用。K562细胞中CBL的缺失会增加AXL和LYN蛋白水平，促进细胞对尼洛替尼的耐药性。相反，在对尼洛替尼耐药的K562细胞（K562-rn）中强制表达CBL会显著降低AXL和LYN的表达，并使K562-rn细胞对尼洛替尼重新敏感。在原发性CML CD34(+)细胞中也发现了类似的机制。从机制上讲，E3连接酶CBL可对抗AXL/SYK信号传导，通过控制AXL蛋白稳定性来促进LYN转录。令人惊讶的是，AXL在耐药中的作用与其配体GAS6的结合及其TK活性无关，这与该受体在这一细胞过程中参与支架活性一致。总体而言，我们的结果表明CBL在控制介导CML细胞对尼洛替尼治疗耐药的酪氨酸激酶网络中起关键作用。
