title: Overcoming Bcr-Abl T315I mutation by combination of GNF-2 and ATP competitors in an Abl-independent mechanism.
abstract: BACKGROUND
  Philadelphia positive leukemias are characterized by the presence of Bcr-Abl fusion protein which exhibits an abnormal kinase activity. Selective Abl kinase inhibitors have been successfully established for the treatment of Ph (+) leukemias. Despite high rates of clinical response, Ph (+) patients can develop resistance against these kinase inhibitors mainly due to point mutations within the Abl protein. Of special interest is the 'gatekeeper' T315I mutation, which confers complete resistance to Abl kinase inhibitors. Recently, GNF-2, Abl allosteric kinase inhibitor, was demonstrated to possess cellular activity against Bcr-Abl transformed cells. Similarly to Abl kinase inhibitors (AKIs), GNF-2 failed to inhibit activity of mutated Bcr-Abl carrying the T315I mutation.
  
  
  METHODS
  Ba/F3 cells harboring native or T315I mutated Bcr-Abl constructs were treated with GNF-2 and AKIs. We monitored the effect of GNF-2 with AKIs on the proliferation and clonigenicity of the different Ba/F3 cells. In addition, we monitored the auto-phosphorylation activity of Bcr-Abl and JAK2 in cells treated with GNF-2 and AKIs.
  
  
  RESULTS
  In this study, we report a cooperation between AKIs and GNF-2 in inhibiting proliferation and clonigenicity of Ba/F3 cells carrying T315I mutated Bcr-Abl. Interestingly, cooperation was most evident between Dasatinib and GNF-2. Furthermore, we showed that GNF-2 was moderately active in inhibiting the activity of JAK2 kinase, and presence of AKIs augmented GNF-2 activity.
  
  
  CONCLUSIONS
  Our data illustrated the ability of allosteric inhibitors such as GNF-2 to cooperate with AKIs to overcome T315I mutation by Bcr-Abl-independent mechanisms, providing a possibility of enhancing AKIs efficacy and overcoming resistance in Ph+ leukemia cells.
authors.affiliation: Cancer Drug Discovery Program, Galilee Technology Center, Migal, P.O.Box 831, Kiryat Shmona 11016, Israel.
authors.forename: Mamduh
authors.initials: M
authors.lastname: Khateb
authors.forename: Nili
authors.initials: N
authors.lastname: Ruimi
authors.forename: Hazem
authors.initials: H
authors.lastname: Khamisie
authors.forename: Yousef
authors.initials: Y
authors.lastname: Najajreh
authors.forename: Afsar
authors.initials: A
authors.lastname: Mian
authors.forename: Anna
authors.initials: A
authors.lastname: Metodieva
authors.forename: Martin
authors.initials: M
authors.lastname: Ruthardt
authors.forename: Jamal
authors.initials: J
authors.lastname: Mahajna
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology* / Q000627:therapeutic use; D045744:Cell Line, Tumor; D004354:Drug Screening Assays, Antitumor / Q000379:methods; D004359:Drug Therapy, Combination / Q000379:methods; D016044:Fusion Proteins, bcr-abl / Q000235:genetics*; D016313:Genes, abl; D006801:Humans; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000188:drug therapy* / Q000235:genetics; D009154:Mutation / Q000187:drug effects; D047428:Protein Kinase Inhibitors / Q000494:pharmacology* / Q000627:therapeutic use; D011743:Pyrimidines / Q000494:pharmacology* / Q000627:therapeutic use
chemical_list: D000970:Antineoplastic Agents; C508526:GNF-2 compound; D047428:Protein Kinase Inhibitors; D011743:Pyrimidines; D016044:Fusion Proteins, bcr-abl