title: RNA interference reveals that ligand-independent met activity is required for tumor cell signaling and survival.
abstract: Hepatocyte growth factor/scatter factor-Met signaling has been implicated in tumor growth, invasion, and metastasis. Suppression of this signaling pathway by targeting the Met protein tyrosine kinase may be an ideal strategy for suppressing malignant tumor growth. Using RNA interference technology and adenovirus vectors carrying small-interfering RNA constructs (Ad Met small-interfering RNA) directed against mouse, canine, and human Met, we can knock down c-met mRNA. We show a dramatic dependence on Met in both ligand-dependent and ligand-independent mouse, canine, and human tumor cell lines. Mouse mammary tumor (DA3) cells and Met-transformed NIH3T3 (M114) cells, as well as both human and canine prostate cancer (PC-3 and TR6LM, human sarcoma (SK-LMS-1), glioblastoma (DBTRG), and gastric cancer (MKN45) cells, all display a dramatic reduction of Met expression after infection with Ad Met small-interfering RNA. In these cells, we observe suppression of tumor cell growth and viability in vitro as well as inhibition of hepatocyte growth factor/scatter factor-mediated scattering and invasion in vitro, whether Met activation was ligand dependent or not. Importantly, Ad Met small-interfering RNA led to apoptotic cell death in many of the tumor cell lines, especially DA3 and MKN45, but did not adversely affect MDCK canine kidney cells. Met small-interfering RNA also abrogated downstream Met signaling to molecules such as Akt and p44/42 mitogen-activated protein kinase. We further show that intratumoral infection with c-met small-interfering RNA adenovirus results in a substantial reduction in tumor growth. Thus, Met small-interfering RNA adenoviruses are reliable tools for studying Met function and raise the possibility of their application for cancer therapy.
authors.affiliation: Laboratory of Molecular Oncology, Van Andel Research Institute, Grand Rapids, Michigan 49503, USA.
authors.forename: Nariyoshi
authors.initials: N
authors.lastname: Shinomiya
authors.forename: Chong Feng
authors.initials: CF
authors.lastname: Gao
authors.forename: Qian
authors.initials: Q
authors.lastname: Xie
authors.forename: Margaret
authors.initials: M
authors.lastname: Gustafson
authors.forename: David J
authors.initials: DJ
authors.lastname: Waters
authors.forename: Yu-Wen
authors.initials: YW
authors.lastname: Zhang
authors.forename: George F
authors.initials: GF
authors.lastname: Vande Woude
mesh_terms: D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D017209:Apoptosis; D045744:Cell Line, Tumor; D004285:Dogs; D006801:Humans; D008024:Ligands; D051379:Mice; D008807:Mice, Inbred BALB C; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009369:Neoplasms / Q000401:mortality / Q000473:pathology* / Q000628:therapy; D010766:Phosphorylation; D011518:Proto-Oncogene Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000502:physiology; D019859:Proto-Oncogene Proteins c-met; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000494:pharmacology; D017978:Receptors, Growth Factor / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000502:physiology; D015398:Signal Transduction
chemical_list: D008024:Ligands; D011518:Proto-Oncogene Proteins; D034741:RNA, Small Interfering; D017978:Receptors, Growth Factor; C491743:MET protein, human; D019859:Proto-Oncogene Proteins c-met; D020928:Mitogen-Activated Protein Kinases