| Summary |
One of the main objective of this study is to characterize Imatinib induced MSCs-mediated resistance evolution in BCR-ABL+ ALL. Tyrosine kinase inhibitor (TKI) Imatinib (IM) is used as a frontline therapy for BCR-ABL–positive (BCR-ABL+) acute lymphoblastic leukemia (ALL). However, resistance to IM therapy develops rapidly in a substantial proportion of treated patients, and the molecular mechanisms underlying the resistance are poorly understood. In this study, we identified a novel cascade of consequential events that are initiated by IM, which traverse through mesenchymal stem/stromal cells (MSCs) to leukemic cells, and lead to IM resistance. Our data showed that MSCs exposed to IM were decreased in their stemness and acquired a new functional status that enabled the formation of leukemic cell niches. These MSCs had increased expression of genes encoding chemo-attractants, adhesion molecules, and pro-survival stimulant growth factors. We found that BCR-ABL+ leukemic cells persistently exposed to IM were able to switch from BCR-ABL–driven signaling to growth factor–driven signaling for survival, and this switch was reversible. Blocking both the BCR-ABL–driven pathway and the growth factor–driven JAK pathway effectively eradicated the leukemic cell niches. Our findings illustrate TKI-induced, MSC-mediated drug resistance, suggesting an effective way to eliminate this type of drug resistance in patients with BCR-ABL+ ALL. |
