BACKGROUND: Imatinib mesylate, a BCR-ABL tyrosine kinase inhibitor, induces apoptosis in chronic myeloid leukemia cells. Resistance to imatinib is currently the most important concern of this treatment. One of the main mechanisms of this resistance is overexpression of BCR-ABL. METHODS: In the current study, the authors investigated the correlation between BCR-ABL overexpression and apoptosis in BaF/BCR-ABL and LAMA84 cell lines resistant to imatinib suddenly deprived of the inhibitor, and compared with their sensitive counterpart. RESULTS: Removal of imatinib from culture medium led to a decrease in Bcr-Abl protein expression by Day 5, which was sustained for > or = 3 weeks of imatinib deprivation. Apoptosis was observed after 3 days of imatinib deprivation in resistant lines accompanied by caspase activation, loss of membrane asymmetry (annexin V staining), and alteration of mitochondrial potential (dihexyloxacarbocyanine iodide [DiOC6]). Transient activation of the STAT5/Bcl-xL pathway and Akt kinase activity preceded these responses. CONCLUSIONS: Thus, imatinib removal led to apoptosis of BCR-ABL-overexpressing leukemic cells, a phenomenon that could be exploited to sensitize imatinib-resistant cells to the cytotoxic effect of other drugs.
BACKGROUND:Imatinib mesylate, a BCR-ABL tyrosine kinase inhibitor, induces apoptosis in chronic myeloid leukemia cells. Resistance to imatinib is currently the most important concern of this treatment. One of the main mechanisms of this resistance is overexpression of BCR-ABL. METHODS: In the current study, the authors investigated the correlation between BCR-ABL overexpression and apoptosis in BaF/BCR-ABL and LAMA84 cell lines resistant to imatinib suddenly deprived of the inhibitor, and compared with their sensitive counterpart. RESULTS: Removal of imatinib from culture medium led to a decrease in Bcr-Abl protein expression by Day 5, which was sustained for > or = 3 weeks of imatinib deprivation. Apoptosis was observed after 3 days of imatinib deprivation in resistant lines accompanied by caspase activation, loss of membrane asymmetry (annexin V staining), and alteration of mitochondrial potential (dihexyloxacarbocyanine iodide [DiOC6]). Transient activation of the STAT5/Bcl-xL pathway and Akt kinase activity preceded these responses. CONCLUSIONS: Thus, imatinib removal led to apoptosis of BCR-ABL-overexpressing leukemic cells, a phenomenon that could be exploited to sensitize imatinib-resistant cells to the cytotoxic effect of other drugs.
Authors: Michael A Dengler; Annette M Staiger; Matthias Gutekunst; Ute Hofmann; Malgorzata Doszczak; Peter Scheurich; Matthias Schwab; Walter E Aulitzky; Heiko van der Kuip Journal: PLoS One Date: 2011-09-20 Impact factor: 3.240
Authors: Monica Ceccon; Maria Elena Boggio Merlo; Luca Mologni; Teresa Poggio; Lydia M Varesio; Matteo Menotti; Silvia Bombelli; Roberta Rigolio; Andrea D Manazza; Filomena Di Giacomo; Chiara Ambrogio; Giovanni Giudici; Cesare Casati; Cristina Mastini; Mara Compagno; Suzanne D Turner; Carlo Gambacorti-Passerini; Roberto Chiarle; Claudia Voena Journal: Oncogene Date: 2015-12-14 Impact factor: 9.867