title: Small interfering RNA against BCR-ABL transcripts sensitize mutated T315I cells to nilotinib.
abstract: BACKGROUND
  Selective inhibition of the BCR-ABL tyrosine kinase by RNA interference has been demonstrated in leukemic cells. We, therefore, evaluated specific BCR-ABL small interfering RNA silencing in BCR-ABL-positive cell lines, including those resistant to imatinib and particularly those with the T315I mutation.
  
  
  METHODS
  The factor-independent 32Dp210 BCR-ABL oligoclonal cell lines and human imatinib-resistant BCR-ABL-positive cells from patients with leukemic disorders were investigated. The effects of BCR-ABL small interfering RNA or the combination of BCR-ABL small interfering RNA with imatinib and nilotinib were compared with those of the ABL inhibitors imatinib and nilotinib.
  
  
  RESULTS
  Co-administration of BCR-ABL small interfering RNA with imatinib or nilotinib dramatically reduced BCR-ABL expression in wild-type and mutated BCR-ABL cells and increased the lethal capacity. BCR-ABL small interfering RNA significantly induced apoptosis and inhibited proliferation in wild-type (P<0.0001) and mutated cells (H396P, T315I, P<0.0001) versus controls. Co-treatment with BCR-ABL small interfering RNA and imatinib or nilotinib resulted in increased inhibition of proliferation and induction of apoptosis in T315I cells as compared to imatinib or nilotinib alone (P<0.0001). Furthermore, the combination of BCR-ABL small interfering RNA with imatinib or nilotinib significantly (P<0.01) reversed multidrug resistance-1 gene-dependent resistance of mutated cells. In T315I cells BCR-ABL small interfering RNA with nilotinib had powerful effects on cell cycle distribution.
  
  
  CONCLUSIONS
  Our data suggest that silencing by BCR-ABL small interfering RNA combined with imatinib or nilotinib may be associated with an additive antileukemic activity against tyrosine kinase inhibitor-sensitive and resistant BCR-ABL cells, and might be an alternative approach to overcome BCR-ABL mutations.
authors.affiliation: Department of Bone Marrow Transplantation, West German Cancer Center, University Hospital of Duisburg-Essen, Hufelandstr. 55 45122 Essen, Germany. michael.koldehoff@uk-essen.de
authors.forename: Michael
authors.initials: M
authors.lastname: Koldehoff
authors.forename: Lambros
authors.initials: L
authors.lastname: Kordelas
authors.forename: Dietrich W
authors.initials: DW
authors.lastname: Beelen
authors.forename: Ahmet H
authors.initials: AH
authors.lastname: Elmaagacli
mesh_terms: D000818:Animals; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D017209:Apoptosis / Q000187:drug effects; D001549:Benzamides; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D003131:Combined Modality Therapy; D019008:Drug Resistance, Neoplasm; D016044:Fusion Proteins, bcr-abl / Q000235:genetics*; D015973:Gene Expression Regulation, Leukemic; D006801:Humans; D000068877:Imatinib Mesylate; D007938:Leukemia / Q000235:genetics* / Q000628:therapy*; D051379:Mice; D009154:Mutation / Q000235:genetics*; D010879:Piperazines / Q000008:administration & dosage; D011743:Pyrimidines / Q000008:administration & dosage; D034741:RNA, Small Interfering / Q000494:pharmacology*
chemical_list: D001549:Benzamides; D010879:Piperazines; D011743:Pyrimidines; D034741:RNA, Small Interfering; D000068877:Imatinib Mesylate; D016044:Fusion Proteins, bcr-abl; C498826:nilotinib