title: Multicolor monitoring of dysregulated protein kinases in chronic myelogenous leukemia.
abstract: The Bcr-Abl and Lyn protein tyrosine kinases have been separately linked to the emergence of imatinib resistance in patients with chronic myelogenous leukemia. We have developed fluorescent sensors for these kinases that are enzymatically and photophysically distinct, allowing us to simultaneously, yet separately, visualize the tyrosine kinase activities of both Abl and Lyn. Multicolor monitoring revealed that an imatinib-resistant cell line (MYL-R) displays a remarkable 13-fold enhancement in Lyn kinase activity relative to its imatinib-sensitive counterpart (MYL). By contrast, both cell lines display nearly identical Abl activities. The upregulation of Lyn kinase phosphotransferase activity in MYL-R cells is linked to an overexpression of the Lyn B isoform. Furthermore, MYL-R cells possess a 4-fold higher level of activated Lyn and 5-fold lower level of autoinhibited Lyn than MYL cells. Finally, studies with an activating SH2 ligand revealed that Lyn from imatinib-resistant MYL-R cells is primed and active, whereas Lyn from imatinib-sensitive cells is dependent upon phosphorylated SH2 ligands for activity.
authors.affiliation: The University of North Carolina at Chapel Hill, 27599, USA.
authors.forename: Qunzhao
authors.initials: Q
authors.lastname: Wang
authors.forename: Eric I
authors.initials: EI
authors.lastname: Zimmerman
authors.forename: Alexei
authors.initials: A
authors.lastname: Toutchkine
authors.forename: Timothy D
authors.initials: TD
authors.lastname: Martin
authors.forename: Lee M
authors.initials: LM
authors.lastname: Graves
authors.forename: David S
authors.initials: DS
authors.lastname: Lawrence
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology; D001549:Benzamides; D015374:Biosensing Techniques / Q000379:methods*; D045744:Cell Line, Tumor; D000069439:Dasatinib; D019008:Drug Resistance, Neoplasm; D005453:Fluorescence; D015973:Gene Expression Regulation, Leukemic / Q000187:drug effects; D006801:Humans; D000068877:Imatinib Mesylate; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000188:drug therapy / Q000201:enzymology*; D010879:Piperazines / Q000494:pharmacology; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011505:Protein-Tyrosine Kinases / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D011743:Pyrimidines / Q000494:pharmacology; D013844:Thiazoles / Q000494:pharmacology; D019061:src-Family Kinases / Q000032:analysis / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*
chemical_list: D000970:Antineoplastic Agents; D001549:Benzamides; D010879:Piperazines; D047428:Protein Kinase Inhibitors; D011743:Pyrimidines; D013844:Thiazoles; D000068877:Imatinib Mesylate; C426236:ARG tyrosine kinase; D011505:Protein-Tyrosine Kinases; C060902:lyn protein-tyrosine kinase; D019061:src-Family Kinases; D000069439:Dasatinib