title: Silencing of GLUT-1 inhibits sensitization of oral cancer cells to cisplatin during hypoxia.
abstract: BACKGROUND
  During tumor development, cells are exposed to a hypoxic microenvironment. Tumor hypoxia also has a profound influence on the sensitivity of cancer chemotherapy. The objective of this study was to investigate the mechanism of cisplatin (CDDP) resistance of oral squamous cell carcinoma (OSCC) cells under hypoxia by analyzing gene expression profiles to identify key genes and factors involved.
  
  
  METHODS
  Cell viability was measured following culture of the cells in the presence or absence of CDDP, under normoxic or hypoxic conditions, using a CCK-8 assay. Analysis of the expression of HIF target genes in hypoxia-treated cells was performed using an HIF-regulated cDNA plate array. Changes in the mRNA expression of selected HIF target genes were analyzed using RT-PCR, and changes in the protein levels of these genes were analyzed by Western blotting. Tumor cell apoptosis was assessed by flow cytometry.
  
  
  RESULTS
  The OSCC cell lines responded differently to CDDP under normoxic and hypoxic conditions. The expression of glucose transporter protein-1 (GLUT-1) was up-regulated in human squamous cell carcinoma of mouth (HSC-2) cells under hypoxia. Furthermore, there was little correlation between the cisplatin sensitivity of human squamous cell carcinoma of tongue (SAS) in normoxia and hypoxia. After GLUT-1 knockdown, CDDP treatment resulted in increased rates of apoptosis under hypoxia as compared with normoxia in cell lines HSC-2, Ca9-22, and SAS (P = 0.025).
  
  
  CONCLUSIONS
  The results of this study suggest that knockdown of GLUT-1 inhibits sensitization of oral squamous cells to CDDP during hypoxia in HSC-2, Ca9-22, and SAS cells.
authors.affiliation: Department of Oral Surgery, Sapporo Medical University, School of Medicine, Sapporo, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Shimanishi
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Ogi
authors.forename: Yohei
authors.initials: Y
authors.lastname: Sogabe
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kaneko
authors.forename: Hironari
authors.initials: H
authors.lastname: Dehari
authors.forename: Akihiro
authors.initials: A
authors.lastname: Miyazaki
authors.forename: Hiroyoshi
authors.initials: H
authors.lastname: Hiratsuka
mesh_terms: D000970:Antineoplastic Agents / Q000627:therapeutic use*; D017209:Apoptosis / Q000187:drug effects; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics; D002294:Carcinoma, Squamous Cell / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology; D018929:Cell Culture Techniques; D016923:Cell Death / Q000187:drug effects / Q000235:genetics; D015687:Cell Hypoxia / Q000502:physiology; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D002470:Cell Survival / Q000187:drug effects; D002945:Cisplatin / Q000627:therapeutic use*; D019008:Drug Resistance, Neoplasm / Q000187:drug effects / Q000235:genetics*; D020869:Gene Expression Profiling; D055785:Gene Knockdown Techniques; D020868:Gene Silencing; D051272:Glucose Transporter Type 1 / Q000235:genetics*; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics; D009062:Mouth Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology; D034741:RNA, Small Interfering / Q000235:genetics; D014062:Tongue Neoplasms / Q000188:drug therapy / Q000473:pathology; D059016:Tumor Microenvironment / Q000187:drug effects / Q000235:genetics; D000099162:Endothelial PAS Domain-Containing Protein 1
chemical_list: D000970:Antineoplastic Agents; D051792:Basic Helix-Loop-Helix Proteins; D002945:Cisplatin; D051272:Glucose Transporter Type 1; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D034741:RNA, Small Interfering; D000099162:Endothelial PAS Domain-Containing Protein 1; C497442:HIF1A protein, human; C495677:SLC2A1 protein, human