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Autophagy induction by Bcr‐Abl‐expressing cells facilitates their recovery from a targeted or nontargeted treatment
Author(s) -
Crowley Lisa C.,
Elzinga Baukje M.,
O'Sullivan Gerald C.,
McKenna Sharon L.
Publication year - 2011
Publication title -
american journal of hematology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.456
H-Index - 105
eISSN - 1096-8652
pISSN - 0361-8609
DOI - 10.1002/ajh.21914
Subject(s) - autophagy , imatinib , cancer research , k562 cells , etoposide , apoptosis , myeloid leukemia , programmed cell death , biology , microbiology and biotechnology , chemotherapy , genetics
Abstract Although Imatinib has transformed the treatment of chronic myeloid leukemia (CML), it is not curative due to the persistence of resistant cells that can regenerate the disease. We have examined how Bcr‐Abl‐expressing cells respond to two mechanistically different therapeutic agents, etoposide and Imatinib. We also examined Bcr‐Abl expression at low and high levels as elevated expression has been associated with treatment failure. Cells expressing low levels of Bcr‐Abl undergo apoptosis in response to the DNA‐targeting agent (etoposide), whereas high‐Bcr‐Abl‐expressing cells primarily induce autophagy. Autophagic populations engage a delayed nonapoptotic death; however, sufficient cells evade this and repopulate following the withdrawal of the drug. Non‐Bcr‐Abl‐expressing 32D or Ba/F3 cells induce both apoptosis and autophagy in response to etoposide and can recover. Imatinib treatment induces both apoptosis and autophagy in all Bcr‐Abl‐expressing cells and populations rapidly recover. Inhibition of autophagy with ATG7 and Beclin1 siRNA significantly reduced the recovery of Imatinib‐treated K562 cells, indicating the importance of autophagy for the recovery of treated cells. Combination regimes incorporating agents that disrupt Imatinib‐induced autophagy would remain primarily targeted and may improve response to the treatment in CML. Am. J. Hematol., 2011. © 2010 Wiley‐Liss, Inc.