Identification of a novel MET mutation in high-grade glioma resulting in an auto-active intracellular protein

Acta Neuropathol. 2015 Jul;130(1):131-44. doi: 10.1007/s00401-015-1420-5. Epub 2015 Apr 11.

Abstract

MET has gained interest as a therapeutic target for a number of malignancies because of its involvement in tumorigenesis, invasion and metastasis. At present, a number of inhibitors, both antibodies against MET or its ligand hepatocyte growth factor, and small molecule MET tyrosine kinase inhibitors are in clinical trials. We here describe a novel variant of MET that is expressed in 6% of high-grade gliomas. Characterization of this mutation in a glioma cell line revealed that it consists of an intronic deletion, resulting in a splice event connecting an intact splice donor site in exon 6 with the next splice acceptor site being that of exon 9. The encoded protein lacks parts of the extracellular IPT domains 1 and 2, encoded by exons 7 and 8, resulting in a novel pseudo-IPT and is named MET(Δ7-8). MET(Δ7-8) is located predominantly in the cytosol and is constitutively active. The auto-activating nature of MET(Δ7-8), in combination with a lack of transmembrane localization, renders MET(Δ7-8) not targetable using antibodies, although the protein is efficiently deactivated by MET-specific tyrosine kinase inhibitors. Testing of MET-expressing tumors for the presence of this variant may be important for treatment decision making.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anilides / pharmacology
  • Animals
  • Antibodies / metabolism
  • Carcinoma / genetics
  • Carcinoma / metabolism
  • Carcinoma / pathology
  • Cell Line, Tumor
  • Female
  • Glioma / drug therapy
  • Glioma / genetics*
  • Glioma / metabolism
  • Glioma / pathology
  • Hepatocyte Growth Factor / metabolism
  • Humans
  • Male
  • Mice
  • Neoplasm Grading
  • Neoplasm Transplantation
  • Prostatic Neoplasms, Castration-Resistant / genetics
  • Prostatic Neoplasms, Castration-Resistant / metabolism
  • Prostatic Neoplasms, Castration-Resistant / pathology
  • Protein Conformation
  • Protein Kinase Inhibitors / pharmacology
  • Proto-Oncogene Proteins c-met / antagonists & inhibitors
  • Proto-Oncogene Proteins c-met / genetics*
  • Proto-Oncogene Proteins c-met / metabolism*
  • Pyridines / pharmacology
  • RNA, Messenger / metabolism
  • Sarcoma / genetics
  • Sarcoma / metabolism
  • Sarcoma / pathology
  • Sequence Deletion*

Substances

  • Anilides
  • Antibodies
  • Protein Kinase Inhibitors
  • Pyridines
  • RNA, Messenger
  • cabozantinib
  • Hepatocyte Growth Factor
  • MET protein, human
  • Proto-Oncogene Proteins c-met