title: Met receptor contributes to trastuzumab resistance of Her2-overexpressing breast cancer cells.
abstract: Her2 is overexpressed in 20% to 30% of breast tumors and correlates with reduced disease-free and overall patient survival. Trastuzumab, a humanized monoclonal antibody directed against Her2, represents the first Her2-targeted therapy, which decreases the risk of relapse and prolongs patient survival. Resistance to trastuzumab, both inherent and treatment-acquired, represents a significant barrier to the effective treatment of Her2 (+) breast cancer. The Met receptor tyrosine kinase is aberrantly expressed in breast cancer and predicts poor patient prognosis. In this study, we find that Met is frequently expressed in Her2-overexpressing breast cancer cells, as well as Her2 (+) breast cancer. Importantly, Met contributes to trastuzumab resistance, as inhibition of Met sensitizes cells to trastuzumab-mediated growth inhibition, whereas Met activation protects cells against trastuzumab by abrogating p27 induction. Remarkably, Her2-overexpressing breast cancer cells rapidly up-regulate Met expression after trastuzumab treatment, promoting their own resistance. Our study suggests that a subset of Her2 (+) patients may benefit from combined inhibition of Her2 and Met.
authors.affiliation: University of California Davis Cancer Center, Sacramento, CA 95817, USA.
authors.forename: David L
authors.initials: DL
authors.lastname: Shattuck
authors.forename: Jamie K
authors.initials: JK
authors.lastname: Miller
authors.forename: Kermit L
authors.initials: KL
authors.lastname: Carraway
authors.forename: Colleen
authors.initials: C
authors.lastname: Sweeney
mesh_terms: D000911:Antibodies, Monoclonal / Q000494:pharmacology*; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents / Q000494:pharmacology; D001940:Breast / Q000473:pathology; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000473:pathology*; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D019008:Drug Resistance, Neoplasm; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic; D018734:Genes, erbB-2; D006801:Humans; D008954:Models, Biological; D010766:Phosphorylation; D019859:Proto-Oncogene Proteins c-met / Q000378:metabolism*; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000235:genetics* / Q000502:physiology*; D000068878:Trastuzumab
chemical_list: D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents; D048049:Extracellular Signal-Regulated MAP Kinases; D019859:Proto-Oncogene Proteins c-met; D018719:Erb-b2 Receptor Tyrosine Kinases; D000068878:Trastuzumab; C508053:ERBB2 protein, human