title: A c-Met inhibitor increases the chemosensitivity of cancer stem cells to the irinotecan in gastric carcinoma.
abstract: BACKGROUND
  Cancer stem cells (CSCs) may be postulated mediators of the chemoresistance. This study aimed to determine an effective signal inhibitor with effects on the proliferation of CSCs in combination with anticancer drugs.
  
  
  METHODS
  We used three gastric cancer cell lines and three side population (SP)-enriched CSC cell lines. We examined the combined effects of inhibitors against stemness signals, including c-Met inhibitor SU11274, and five anticancer drugs on the CSC proliferation and mRNA expression of chemoresistance-associated genes.
  
  
  RESULTS
  The IC50 of irinotecan in SP-enriched CSC was 10.5 times higher than parent OCUM-2M cells, whereas that of oxaliplatin, taxol, gemcitabine, and 5-fluorouracil was 2.0, 2.8, 2.0, and 1.2, respectively. The SP cell lines had higher expression levels of UGT1A1, ABCG2, and ABCB1 than their parent cell lines. There was a synergistic antiproliferative effect with a combination of SU11274 and SN38 in SP cells, but not other inhibitors. The SU11274 significantly decreased the expression of UGT1A1, but not ABCG2 and ABCB1. The SN38 plus SU11274 group more effectively suppressed in vivo tumour growth by OCUM-2M/SP cells than either group alone.
  
  
  CONCLUSIONS
  Cancer stem cells have chemoresistance to irinotecan. The c-Met inhibitor may be a promising target molecule for irinotecan-based chemotherapy of gastric cancer.
authors.affiliation: 1] Department of Surgical Oncology, Osaka City University Graduate School of Medicine, 1-4-3 Asahi-machi, Abeno-ku, Osaka 545-8585, Japan [2] Oncology Institute of Geriatrics and Medical Science, Osaka City University Graduate School of Medicine, 1-4-3 Asahi-machi, Abeno-ku, Osaka 545-8585, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Yashiro
authors.forename: T
authors.initials: T
authors.lastname: Nishii
authors.forename: T
authors.initials: T
authors.lastname: Hasegawa
authors.forename: T
authors.initials: T
authors.lastname: Matsuzaki
authors.forename: T
authors.initials: T
authors.lastname: Morisaki
authors.forename: T
authors.initials: T
authors.lastname: Fukuoka
authors.forename: K
authors.initials: K
authors.lastname: Hirakawa
mesh_terms: D000818:Animals; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology / Q000627:therapeutic use*; D002166:Camptothecin / Q000031:analogs & derivatives* / Q000494:pharmacology / Q000627:therapeutic use; D019008:Drug Resistance, Neoplasm / Q000187:drug effects; D004357:Drug Synergism; D006801:Humans; D000077146:Irinotecan; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D014411:Neoplastic Stem Cells / Q000187:drug effects* / Q000473:pathology; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D019859:Proto-Oncogene Proteins c-met / Q000037:antagonists & inhibitors*; D013274:Stomach Neoplasms / Q000188:drug therapy* / Q000473:pathology; D014407:Tumor Cells, Cultured; D023041:Xenograft Model Antitumor Assays
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D047428:Protein Kinase Inhibitors; D000077146:Irinotecan; D019859:Proto-Oncogene Proteins c-met; D002166:Camptothecin