Phosphorylation of the ATP-binding loop directs oncogenicity of drug-resistant BCR-ABL mutants

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 103; no. 51; pp. 19466 - 19471
• Main Authors: Skaggs, Brian J, Gorre, Mercedes E, Ryvkin, Ann, Burgess, Michael R, Xie, Yongming, Han, Yun, Komisopoulou, Evangelia, Brown, Lauren M, Loo, Joseph A, Landaw, Elliot M, Sawyers, Charles L, Graeber, Thomas G
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 19.12.2006; National Acad Sciences
• Subjects: Adenosine triphosphatase; Adenosine Triphosphate - metabolism; Alleles; Amino Acid Sequence; Animals; Biological Sciences; Bone marrow; Cancer; Cell Line; Chronic myeloid leukemia; DNA Mutational Analysis; Drug resistance; Drug Resistance, Neoplasm - genetics; Enzymes; Fusion Proteins, bcr-abl - genetics; Fusion Proteins, bcr-abl - metabolism; Kinases; Leukemia; Lung neoplasms; Mass Spectrometry; Mass spectroscopy; Mice; Molecular Sequence Data; Mutation; Mutation, Missense - genetics; Phosphorylation; Protein Binding; Protein Kinase Inhibitors - metabolism; Proteomics; Signatures
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.0609239103

The success of targeting kinases in cancer with small molecule inhibitors has been tempered by the emergence of drug-resistant kinase domain mutations. In patients with chronic myeloid leukemia treated with ABL inhibitors, BCR-ABL kinase domain mutations are the principal mechanism of relapse. Certain mutations are occasionally detected before treatment, suggesting increased fitness relative to wild-type p210 BCR-ABL. We evaluated the oncogenicity of eight kinase inhibitor-resistant BCR-ABL mutants and found a spectrum of potencies greater or less than p210. Although most fitness alterations correlate with changes in kinase activity, this is not the case with the T315I BCR-ABL mutation that confers clinical resistance to all currently approved ABL kinase inhibitors. Through global phosphoproteome analysis, we identified a unique phosphosubstrate signature associated with each drug-resistant allele, including a shift in phosphorylation of two tyrosines (Tyr²⁵³ and Tyr²⁵⁷) in the ATP binding loop (P-loop) of BCR-ABL when Thr³¹⁵ is Ile or Ala. Mutational analysis of these tyrosines in the context of Thr³¹⁵ mutations demonstrates that the identity of the gatekeeper residue impacts oncogenicity by altered P-loop phosphorylation. Therefore, mutations that confer clinical resistance to kinase inhibitors can substantially alter kinase function and confer novel biological properties that may impact disease progression.