title: A neurotrophin axis in myeloma: TrkB and BDNF promote tumor-cell survival.
abstract: Multiple myeloma (MM) is a B-cell neoplasm that is characterized by the clonal expansion of malignant plasma cells and is frequently associated with chromosomal translocations placing an oncogene under the control of the immunoglobulin heavy chain enhancer. Despite these pathogenic translocations, MM cells remain dependent on external cues for survival. We present evidence that brain-derived neurotrophic factor (BDNF), a member of the neurotrophin family of growth factors, and its high-affinity receptor, tropomyosin receptor kinase B (TrkB), contribute to these survival cues. MM cells express TrkB, and respond to BDNF by activating mitogen-activated protein kinase (MAPK) and phosphatidylinositol-3 kinase-a PI3K target (PI3K/Akt) signaling cascades. Addition of BDNF protects human MM cell lines (HMCLs) from apoptosis induced by dexamethasone or bortezomib and prolongs the survival of primary MM cells cultured alone or with human bone marrow (BM) stroma. As BDNF and TrkB are expressed by osteoblasts, stromal cells, and endothelial cells within the BM microenvironment, a BDNF-TrkB axis may be critical to the interactions of MM with bone and stroma that contribute to MM tumor progression. Finally, BDNF is expressed by malignant plasma cells isolated from a subset of patients with MM, as well as by most HMCLs, suggesting a potential role for this neurotrophin axis in autocrine as well as paracrine support of MM.
authors.affiliation: Division of Hematology, Cornell University Medical College, Rm C-606, 1300 York Ave, New York, NY 10021, USA. rnp2001@med.cornell.edu
authors.forename: Roger N
authors.initials: RN
authors.lastname: Pearse
authors.forename: Steven L
authors.initials: SL
authors.lastname: Swendeman
authors.forename: Ying
authors.initials: Y
authors.lastname: Li
authors.forename: Dahlia
authors.initials: D
authors.lastname: Rafii
authors.forename: Barbara L
authors.initials: BL
authors.lastname: Hempstead
mesh_terms: D019898:Autocrine Communication; D001897:Boronic Acids / Q000494:pharmacology; D000069286:Bortezomib; D019208:Brain-Derived Neurotrophic Factor / Q000494:pharmacology*; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D018920:Coculture Techniques; D003907:Dexamethasone / Q000494:pharmacology; D006801:Humans; D009101:Multiple Myeloma / Q000737:chemistry / Q000209:etiology / Q000473:pathology*; D009414:Nerve Growth Factors / Q000502:physiology*; D019899:Paracrine Communication; D011719:Pyrazines / Q000494:pharmacology; D020813:Receptor, trkB / Q000502:physiology*; D015398:Signal Transduction; D017154:Stromal Cells / Q000166:cytology
chemical_list: D001897:Boronic Acids; D019208:Brain-Derived Neurotrophic Factor; D009414:Nerve Growth Factors; D011719:Pyrazines; D000069286:Bortezomib; D003907:Dexamethasone; D020813:Receptor, trkB