Oligomerization inhibition, combined with allosteric inhibition, abrogates the transformation potential of T315I-positive BCR/ABL

Leukemia. 2009 Dec;23(12):2242-7. doi: 10.1038/leu.2009.194. Epub 2009 Oct 1.

Abstract

The t(9;22) translocation leads to the formation of the chimeric bcr/abl fusion gene, which encodes the BCR/ABL fusion protein. In contrast to its physiological counterpart c-ABL, the BCR/ABL kinase is constitutively activated, inducing the leukemic phenotype. The N-terminus of c-ABL (Cap region) contributes to the regulation of its kinase function. It is myristoylated, and the myristate residue binds to a hydrophobic pocket in the kinase domain known as the myristoyl-binding pocket in a process called 'capping', which results in an auto-inhibited conformation. Because the cap region is replaced by the N-terminus of BCR, the BCR/ABL 'escapes' this auto-inhibition. Allosteric inhibition by myristate 'mimics', such as GNF-2, is able to inhibit unmutated BCR/ABL, but not the BCR/ABL that harbors the 'gatekeeper' mutation T315I. In this study, we analyzed the possibility of increasing the efficacy of allosteric inhibition by blocking BCR/ABL oligomerization. We showed that inhibition of oligomerization was able to not only increase the efficacy of GNF-2 on unmutated BCR/ABL, but also overcome the resistance of BCR/ABL-T315I to allosteric inhibition. These results strongly suggest that the response to allosteric inhibition by GNF-2 is inversely related to the degree of oligomerization of BCR/ABL. In summary, our observations establish a new approach for the molecular targeting of BCR/ABL and its resistant mutants represented by the combination of oligomerization and allosteric inhibitors.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Allosteric Regulation / drug effects*
  • Animals
  • Cell Line
  • Cell Proliferation / drug effects
  • Cell Transformation, Neoplastic / chemistry
  • Cell Transformation, Neoplastic / drug effects*
  • Cell Transformation, Neoplastic / genetics*
  • Cell Transformation, Neoplastic / metabolism
  • Fusion Proteins, bcr-abl / drug effects
  • Fusion Proteins, bcr-abl / genetics*
  • Fusion Proteins, bcr-abl / metabolism
  • Mice
  • Mutation, Missense*
  • Phosphorylation / drug effects
  • Protein Multimerization / drug effects*
  • Pyrimidines / pharmacology
  • Pyrimidines / therapeutic use
  • Rats

Substances

  • GNF-2 compound
  • Pyrimidines
  • Fusion Proteins, bcr-abl