We investigated the effects of AKIs in combination with the allosteric inhibitor GNF2 in Ph + leukemia. Methods: The efficacy of this approach on the leukemogenic potential of BCR/ABL was studied in Ba/F3 cells, primary murine bone marrow cells, and untransformed Rat-1 fibroblasts expressing BCR/ABL or BCR/ABL-T315I as well as in patient-derived long-term cultures (PDLTC) from Ph + ALL-patients. Results: Here, we show that GNF-2 increased the effects of AKIs on unmutated BCR/ABL. Interestingly, the combination of Dasatinib and GNF-2 overcame resistance of BCR/ABL-T315I in all models used in a synergistic manner. Conclusions: Our observations establish a new approach for the molecular targeting of BCR/ABL and its resistant mutants using a combination of AKIs and allosteric inhibitors. Keywords: Philadelphia chromosome, BCR/ABL, “gatekeeper” mutation T315I, Allosteric inhibition, Abl kinase inhibitors, Molecular therapyBackground Chronic myeloid leukemia (CML) and 30 of adult acute lymphatic leukemia (ALL) are characterized by the Philadelphia chromosome (Ph+), which is the cytogenetic correlate of the (9;22) chromosomal translocation. The t(9;22) leads to the fusion of the breakpoint ICG-001 chemical information cluster region (BCR) gene and the Abelson tyrosine kinase (ABL1). BCR/ABL results in a deregulated and constitutively activated tyrosine kinase, which is responsible for the induction of the phenotype of Ph + leukemia. BCR/* Correspondence: [email protected] 1 Department of Hematology, Goethe University, Frankfurt, Germany 5 Labor f Tumorstammzellbiologie, Med. Klinik II/H atologie, Klinikum der Goethe Universit Frankfurt, Theodor Stern Kai 7, 60590 Frankfurt, Germany Full list of author information is available at the end of the articleABL constitutively activates several signaling pathways leading to uncontrolled proliferation and inhibition of apoptosis. The expression of BCR/ABL is sufficient for the initiation and maintenance of early stage CML and the “CML-like disease” in mice [1,2]. Selective targeting of BCR/ABL by ABL-kinase inhibitors (AKI) such as Imatinib, Nilotinib or Dasatinib, all competitive ATP-analogues, leads to durable cytogenetic and molecular remissions in the majority of CML patients in the early chronic phase of the disease. However, unsatisfactory responses in advanced disease stages, resistance and long-term tolerability of BCR/ABL inhibitors represent major clinical problems. In fact, advanced CML and Ph + ALL respond only transiently to AKIs [3,4]. Secondary resistance is mostly caused by the?2012 Mian et al.; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted PubMed ID:https://www.ncbi.nlm.nih.gov/pubmed/25636517 use, distribution, and reproduction in any medium, provided the original work is properly cited.Mian et al. BMC Cancer 2012, 12:411 http://www.biomedcentral.com/1471-2407/12/Page 2 ofacquisition of point mutations in BCR/ABL that interfere with the affinity for these ATP competitors. The second-generation inhibitors Nilotinib and Dasatinib target most resistant BCR/ABL mutants [5,6] with the exception of the “gatekeeper” mutation T315I. T315I is the most clinically relevant mutation because it confers a global resistance against all available molecular therapy approaches [3,4]. The activation status of wild-type c-ABL is finely regulated by several regulation signals. Myristoylation of the N-terminus of c-ABL.
