title: Evidence that resistance to nilotinib may be due to BCR-ABL, Pgp, or Src kinase overexpression.
abstract: Targeting the tyrosine kinase activity of Bcr-Abl is an attractive therapeutic strategy in chronic myeloid leukemia (CML) and in Bcr-Abl-positive acute lymphoblastic leukemia. Whereas imatinib, a selective inhibitor of Bcr-Abl tyrosine kinase, is now used in frontline therapy for CML, second-generation inhibitors of Bcr-Abl tyrosine kinase such as nilotinib or dasatinib have been developed for the treatment of imatinib-resistant or imatinib-intolerant disease. In the current study, we generated nilotinib-resistant cell lines and investigated their mechanism of resistance. Overexpression of BCR-ABL and multidrug resistance gene (MDR-1) were found among the investigated mechanisms. We showed that nilotinib is a substrate of the multidrug resistance gene product, P-glycoprotein, using verapamil or PSC833 to block binding. Up-regulated expression of p53/56 Lyn kinase, both at the mRNA and protein level, was found in one of the resistant cell lines and Lyn silencing by small interfering RNA restored sensitivity to nilotinib. Moreover, failure of nilotinib treatment was accompanied by an increase of Lyn mRNA expression in patients with resistant CML. Two Src kinase inhibitors (PP1 and PP2) partially removed resistance but did not significantly inhibit Bcr-Abl tyrosine kinase activity. In contrast, dasatinib, a dual Bcr-Abl and Src kinase inhibitor, inhibited the phosphorylation of both BCR-ABL and Lyn, and induced apoptosis of the Bcr-Abl cell line overexpressing p53/56 Lyn. Such mechanisms of resistance are close to those observed in imatinib-resistant cell lines and emphasize the critical role of Lyn in nilotinib resistance.
authors.affiliation: Hématopoïèse Leucémique et Cible Thérapeutique, INSERM U876, Université Victor Ségalen, Laboratoire d'hématologie CHU de Bordeaux, Bordeaux cedex, France.
authors.forename: François-Xavier
authors.initials: FX
authors.lastname: Mahon
authors.forename: Sandrine
authors.initials: S
authors.lastname: Hayette
authors.forename: Valérie
authors.initials: V
authors.lastname: Lagarde
authors.forename: Francis
authors.initials: F
authors.lastname: Belloc
authors.forename: Béatrice
authors.initials: B
authors.lastname: Turcq
authors.forename: Franck
authors.initials: F
authors.lastname: Nicolini
authors.forename: Coralie
authors.initials: C
authors.lastname: Belanger
authors.forename: Paul W
authors.initials: PW
authors.lastname: Manley
authors.forename: Cédric
authors.initials: C
authors.lastname: Leroy
authors.forename: Gabriel
authors.initials: G
authors.lastname: Etienne
authors.forename: Serge
authors.initials: S
authors.lastname: Roche
authors.forename: Jean-Max
authors.initials: JM
authors.lastname: Pasquet
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000096:biosynthesis* / Q000378:metabolism; D000970:Antineoplastic Agents; D000069439:Dasatinib; D019008:Drug Resistance, Neoplasm; D016044:Fusion Proteins, bcr-abl / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D020014:K562 Cells; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000188:drug therapy* / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D011743:Pyrimidines / Q000494:pharmacology*; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics; D013844:Thiazoles / Q000494:pharmacology; D014162:Transfection; D019061:src-Family Kinases / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000970:Antineoplastic Agents; D011743:Pyrimidines; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D013844:Thiazoles; D016044:Fusion Proteins, bcr-abl; C060902:lyn protein-tyrosine kinase; D019061:src-Family Kinases; C498826:nilotinib; D000069439:Dasatinib