title: Hepatoblastoma cells express truncated neurokinin-1 receptor and can be growth inhibited by aprepitant in vitro and in vivo.
abstract: OBJECTIVE
  Multidrug resistance presents a major problem in hepatoblastoma (HB), and new anti-tumor strategies are desperately needed. The substance P (SP)/neurokinin-1 receptor (NK1R) complex has been discovered to be pivotal in the development of a variety of human cancers, and NK1R antagonists, such as the clinical drug aprepitant, are promising future anticancer agents. Yet, the role of the SP/NK1R complex as a potential anticancer target in HB is unknown.
  
  
  METHODS
  Human HB cell lines HepT1, HepG2, and HuH6, human tumor samples from 17 children with HB as well as mice xenografted with human HB cell line HuH6 were analyzed regarding the SP/NK1R complex as a potential new anti-tumor target in HB.
  
  
  RESULTS
  Therapeutic targeting with the NK1R antagonists aprepitant, L-733,060, and L-732,138 led to growth inhibition and apoptosis in HepT1, HepG2, and HuH6 cells in a dose-dependent manner. Intriguingly, HB cells predominantly expressed the truncated splice variant of NK1R. Human fibroblasts showed only dismal NK1R expression and were significantly more resistant. Stimulation of HB cells with SP, NK1R's natural ligand, caused increased growth rates and abrogated the anti-proliferative effect of NK1R antagonists. Expression analysis of 17 human HB samples confirmed the clinical relevance of NK1R. Most importantly, oral treatment of a HuH6 xenograft mouse model with 80mg/kg/day aprepitant for 24days resulted in a striking reduction of tumor growth, as evidenced by reduced tumor volume and weight, lowered tumor-specific alpha-fetoprotein (AFP) serum levels, and decreased number of Ki-67 positive cells. Furthermore, aprepitant treatment inhibited in vivo angiogenesis.
  
  
  CONCLUSIONS
  For the first time, we describe the NK1R in its truncated splice variant as a potent target in human HB and an inhibitory effect in vivo and in vitro by NK1R antagonists. Therefore, NK1R antagonists should be considered promising new candidates for innovative therapeutic strategies against HB.
authors.affiliation: Division of Pediatric Infectious Disease and Immunopathology, Virgen del Rocío Children's Hospital, Institute of Biomedicine, Seville, Spain; Department of Pediatric Surgery, Research Laboratories, Dr. von Hauner Children's Hospital, Ludwig-Maximilians-University Munich, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Berger
authors.affiliation: Division of Pediatric Infectious Disease and Immunopathology, Virgen del Rocío Children's Hospital, Institute of Biomedicine, Seville, Spain.
authors.forename: Olaf
authors.initials: O
authors.lastname: Neth
authors.affiliation: Department of Translational Molecular Pathology, MD Anderson Cancer Center, University of Texas Health Science Center at Houston, TX, USA.
authors.forename: Matthias
authors.initials: M
authors.lastname: Ilmer
authors.affiliation: Department of Pediatric Surgery, Research Laboratories, Dr. von Hauner Children's Hospital, Ludwig-Maximilians-University Munich, Germany.
authors.forename: Agnès
authors.initials: A
authors.lastname: Garnier
authors.affiliation: Department of Pathology, Juan Ramón Jiménez Hospital, Huelva, Spain.
authors.forename: Manuel Vicente
authors.initials: MV
authors.lastname: Salinas-Martín
authors.affiliation: Department of Pediatric Surgery, Virgen del Rocío Children's Hospital, Seville, Spain.
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: de Agustín Asencio
authors.affiliation: Department of Pediatric Surgery, Research Laboratories, Dr. von Hauner Children's Hospital, Ludwig-Maximilians-University Munich, Germany.
authors.forename: Dietrich
authors.initials: D
authors.lastname: von Schweinitz
authors.affiliation: Department of Pediatric Surgery, Research Laboratories, Dr. von Hauner Children's Hospital, Ludwig-Maximilians-University Munich, Germany.
authors.forename: Roland
authors.initials: R
authors.lastname: Kappler
authors.affiliation: Research Laboratory on Neuropeptides, Virgen del Rocío Children's Hospital, Seville, Spain. Electronic address: mmunoz@cica.es.
authors.forename: Miguel
authors.initials: M
authors.lastname: Muñoz
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D000077608:Aprepitant; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002648:Child; D054697:Cytostatic Agents / Q000008:administration & dosage; D004357:Drug Synergism; D005260:Female; D015870:Gene Expression; D056945:Hep G2 Cells; D018197:Hepatoblastoma / Q000188:drug therapy* / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D008113:Liver Neoplasms / Q000188:drug therapy* / Q000378:metabolism* / Q000473:pathology; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D009025:Morpholines / Q000008:administration & dosage / Q000494:pharmacology*; D009389:Neovascularization, Pathologic / Q000517:prevention & control; D064729:Neurokinin-1 Receptor Antagonists / Q000008:administration & dosage / Q000494:pharmacology*; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D018040:Receptors, Neurokinin-1 / Q000235:genetics / Q000378:metabolism*; D013373:Substance P / Q000378:metabolism / Q000494:pharmacology; D023041:Xenograft Model Antitumor Assays
chemical_list: D054697:Cytostatic Agents; D009025:Morpholines; D064729:Neurokinin-1 Receptor Antagonists; D020033:Protein Isoforms; D018040:Receptors, Neurokinin-1; D000077608:Aprepitant; D013373:Substance P
keywords: Anti-tumor target; Apoptosis; Aprepitant; Hepatoblastoma (HB); Neurokinin-1 receptor (NK1R); Substance P (SP); Xenograft