Microenvironmental protection of CML stem and progenitor cells from tyrosine kinase inhibitors through N-Cadherin and Wnt-β-catenin signaling
Menée à l'aide de xénogreffes de leucémie myéloïde chronique, cette étude met en évidence un mécanisme par lequel les voies de signalisation N-cadhérine et Wnt-β-caténine coopèrent pour protéger les cellules souches leucémiques des effets d'un traitement par inhibiteur de tyrosine kinase
Tyrosine kinase inhibitors (TKI) are highly effective in treatment of chronic myeloid leukemia (CML) but do not eliminate leukemia stem cells (LSC), which remain a potential source of relapse. TKI treatment effectively inhibits BCR-ABL kinase activity in CML LSC, suggesting that additional kinase-independent mechanisms contribute to LSC preservation. We investigated whether signals from the bone marrow (BM) microenvironment protect CML LSC from TKI treatment. Coculture with human BM mesenchymal stromal cells (MSC) significantly inhibited apoptosis and preserved CML stem/progenitor cells following TKI exposure, maintaining colony forming ability and engraftment potential in immunodeficient mice. We found that the N-Cadherin receptor plays an important role in MSC-mediated protection of CML progenitors from TKI. N-Cadherin-mediated adhesion to MSC was associated with increased cytoplasmic N-Cadherin-β-catenin complex formation, as well as enhanced β-catenin nuclear translocation and transcriptional activity. Increased exogenous Wnt-mediated β-catenin signaling played an important role in MSC-mediated protection of CML progenitors from TKI treatment. Our results reveal a close interplay between N-Cadherin and the Wnt-β-catenin pathway in protecting CML LSC during TKI treatment. Importantly, these results reveal novel mechanisms of resistance of CML LSC to TKI treatment, and suggest new targets for treatment designed to eradicate residual LSC in CML patients.
Blood 2013