ABSTRACT
Because oncogene MET and EGF receptor (EGFR) inhibitors are in clinical development against several types of cancer, including glioblastoma, it is important to identify predictive markers that indicate patient subgroups suitable for such therapies. We investigated in vivo glioblastoma models characterized by hepatocyte growth factor (HGF) autocrine or paracrine activation, or by MET or EGFR amplification, for their susceptibility to MET inhibitors. HGF autocrine expression correlated with high phospho-MET levels in HGF autocrine cell lines, and these lines showed high sensitivity to MET inhibition in vivo. An HGF paracrine environment may enhance glioblastoma growth in vivo but did not indicate sensitivity to MET inhibition. EGFRvIII amplification predicted sensitivity to EGFR inhibition, but in the same tumor, increased copies of MET from gains of chromosome 7 did not result in increased MET activity and did not predict sensitivity to MET inhibitors. Thus, HGF autocrine glioblastoma bears an activated MET signaling pathway that may predict sensitivity to MET inhibitors. Moreover, serum HGF levels may serve as a biomarker for the presence of autocrine tumors and their responsiveness to MET therapeutics.
Subject(s)
Autocrine Communication/physiology , Biomarkers/metabolism , ErbB Receptors/metabolism , Glioblastoma/metabolism , Hepatocyte Growth Factor/metabolism , Proto-Oncogene Proteins c-met/metabolism , Biomarkers/blood , Blotting, Western , Cell Line, Tumor , Cluster Analysis , Comparative Genomic Hybridization , DNA Primers/genetics , Enzyme-Linked Immunosorbent Assay , Gene Expression Regulation, Neoplastic/drug effects , Glioblastoma/blood , Hepatocyte Growth Factor/blood , Humans , In Situ Hybridization, Fluorescence , Microarray Analysis , Proto-Oncogene Proteins c-met/antagonists & inhibitors , Pyridazines/pharmacology , Reverse Transcriptase Polymerase Chain Reaction , Triazoles/pharmacologyABSTRACT
The hepatocyte growth factor (HGF)-MET pathway supports several hallmark cancer traits, and it is frequently activated in a broad spectrum of human cancers (http://www.vai.org/met/). With the development of many cancer drugs targeting this pathway, there is a need for relevant in vivo model systems for preclinical evaluation of drug efficacy. Here, we show that production of the human HGF ligand in transgenic severe combined immunodeficient mice (hHGF(tg)-SCID mice) enhances the growth of many MET-expressing human carcinoma xenografts, including those derived from lung, breast, kidney, colon, stomach, and pancreas. In this model, the MET-specific small-molecule kinase inhibitor SGX523 partially inhibits the HGF-dependent growth of lung, breast, and pancreatic tumors. However, much greater growth suppression is achieved by combinatorial inhibition with the epidermal growth factor receptor (EGFR) kinase inhibitor erlotinib. Together, these results validate the hHGF(tg)-SCID mouse model for in vivo determination of MET sensitivity to drug inhibition. Our findings also indicate that simultaneously targeting the MET and EGFR pathways can provide synergistic inhibitory effects for the treatment of cancers in which both pathways are activated.