title: TrkB induces EMT and has a key role in invasion of head and neck squamous cell carcinoma.
abstract: Head and neck squamous cell carcinoma (HNSCC) remains a significant public health problem, accounting for over 5% of all cancer-related deaths, and these deaths primarily result from metastatic disease. The molecular processes involved in HNSCC pathogenesis and progression are poorly understood, and here we present experimental evidence for a direct role of the cell surface receptor tyrosine kinase, TrkB, in HNSCC tumor progression. Using immunohistochemical analysis and transcriptional profiling of archival HNSCC tumor specimens, we found that TrkB and its secreted ligand, brain-derived neurotrophic factor (BDNF), are expresses in greater than 50% of human HNSCC tumors, but not in normal upper aerodigestive tract (UADT) epithelia. Studies with HNSCC cell lines reveal that in vitro stimulation with BDNF, the ligand for TrkB, upregulates the migration and invasion of HNSCC cells, and both transient and stable suppressions of TrkB result in significant abrogation of constitutive and ligand-mediated migration and invasion. Furthermore, enforced overexpression of TrkB results in altered expression of molecular mediators of epithelial-to-mesenchymal transition (EMT), including downregulation of E-cadherin and upregulation of Twist. Using an in vivo mouse model of HNSCC, we were able to show that downregulation of TrkB suppresses tumor growth. These results directly implicate TrkB in EMT and the invasive behavior of HNSCC, and correlate with the in vivo overexpression of TrkB in human HNSCC. Taken together, these data suggest that the TrkB receptor may be a critical component in the multi-step tumor progression of HNSCC, and may be an attractive target for much needed new therapies for this disease.
authors.affiliation: Department of Head and Neck Surgery, Houston TX, USA. mekupfer@mdanderson.org
authors.forename: M E
authors.initials: ME
authors.lastname: Kupferman
authors.forename: T
authors.initials: T
authors.lastname: Jiffar
authors.forename: A
authors.initials: A
authors.lastname: El-Naggar
authors.forename: T
authors.initials: T
authors.lastname: Yilmaz
authors.forename: G
authors.initials: G
authors.lastname: Zhou
authors.forename: T
authors.initials: T
authors.lastname: Xie
authors.forename: L
authors.initials: L
authors.lastname: Feng
authors.forename: J
authors.initials: J
authors.lastname: Wang
authors.forename: F C
authors.initials: FC
authors.lastname: Holsinger
authors.forename: D
authors.initials: D
authors.lastname: Yu
authors.forename: J N
authors.initials: JN
authors.lastname: Myers
mesh_terms: D000818:Animals; D019208:Brain-Derived Neurotrophic Factor / Q000378:metabolism; D002294:Carcinoma, Squamous Cell / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D002454:Cell Differentiation; D045744:Cell Line, Tumor; D002471:Cell Transformation, Neoplastic; D002633:Chemotaxis; D018450:Disease Progression; D015536:Down-Regulation; D004789:Enzyme Activation; D004847:Epithelial Cells / Q000473:pathology*; D015972:Gene Expression Regulation, Neoplastic; D055785:Gene Knockdown Techniques; D006258:Head and Neck Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D008024:Ligands; D008297:Male; D008648:Mesoderm / Q000473:pathology*; D051379:Mice; D009361:Neoplasm Invasiveness; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D020813:Receptor, trkB / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D015854:Up-Regulation
chemical_list: D019208:Brain-Derived Neurotrophic Factor; D008024:Ligands; D020813:Receptor, trkB; D051057:Proto-Oncogene Proteins c-akt