title: Increased p38-MAPK is responsible for chemotherapy resistance in human gastric cancer cells.
abstract: BACKGROUND
  Chemoresistance is one of the main obstacles to successful cancer therapy and is frequently associated with Multidrug resistance (MDR). Many different mechanisms have been suggested to explain the development of an MDR phenotype in cancer cells. One of the most studied mechanisms is the overexpression of P-glycoprotein (P-gp), which is a product of the MDR1 gene. Tumor cells often acquire the drug-resistance phenotype due to upregulation of the MDR1 gene. Overexpression of MDR1 gene has often been reported in primary gastric adenocarcinoma.
  
  
  METHODS
  This study investigated the role of p38-MAPK signal pathway in vincristine-resistant SGC7901/VCR cells. P-gp and MDR1 RNA were detected by Western blot analysis and RT-PCR amplification. Mitgen-activated protein kinases and function of P-gp were demonstrated by Western blot and FACS Aria cytometer analysis. Ap-1 activity and cell apoptosis were detected by Dual-Luciferase Reporter Assay and annexin V-PI dual staining.
  
  
  RESULTS
  The vincristine-resistant SGC7901/VCR cells with increased expression of the multidrug-resistance 1 (MDR1) gene were resistant to P-gp-related drug and P-gp-unrelated drugs. Constitutive increases of phosphorylated p38-MAPK and AP-1 activities were also found in the drug-resistant cells. Inhibition of p38-MAPK by SB202190 reduced activator protein-1 (AP-1) activity and MDR1 expression levels and increased the sensitivity of SGC7901/VCR cells to chemotherapy.
  
  
  CONCLUSIONS
  Activation of the p38-MAPK pathway might be responsible for the modulation of P-glycoprotein-mediated and P-glycoprotein-unmediated multidrug resistance in the SGC7901/VCR cell line.
authors.affiliation: Tumor Immunology and Gene Therapy Center, Eastern Hepatobiliary Surgery Hospital, the Second Military Medical University, Shanghai, PR China. guoguo1188@gmail.com
authors.forename: Xianling
authors.initials: X
authors.lastname: Guo
authors.forename: Nannan
authors.initials: N
authors.lastname: Ma
authors.forename: Jin
authors.initials: J
authors.lastname: Wang
authors.forename: Jianrui
authors.initials: J
authors.lastname: Song
authors.forename: Xinxin
authors.initials: X
authors.lastname: Bu
authors.forename: Yue
authors.initials: Y
authors.lastname: Cheng
authors.forename: Kai
authors.initials: K
authors.lastname: Sun
authors.forename: Haiyan
authors.initials: H
authors.lastname: Xiong
authors.forename: Guocheng
authors.initials: G
authors.lastname: Jiang
authors.forename: Baihe
authors.initials: B
authors.lastname: Zhang
authors.forename: Mengchao
authors.initials: M
authors.lastname: Wu
authors.forename: Lixin
authors.initials: L
authors.lastname: Wei
mesh_terms: D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000378:metabolism; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology; D017209:Apoptosis; D015153:Blotting, Western; D045744:Cell Line, Tumor; D019008:Drug Resistance, Neoplasm / Q000502:physiology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005434:Flow Cytometry; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D020128:Inhibitory Concentration 50; D020935:MAP Kinase Signaling System / Q000502:physiology; D010766:Phosphorylation; D011725:Pyridines / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013274:Stomach Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D018808:Transcription Factor AP-1 / Q000378:metabolism; D014750:Vincristine / Q000494:pharmacology*; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: C513055:ABCB1 protein, human; D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000972:Antineoplastic Agents, Phytogenic; D004791:Enzyme Inhibitors; D007093:Imidazoles; D011725:Pyridines; D012333:RNA, Messenger; D018808:Transcription Factor AP-1; D014750:Vincristine; D048051:p38 Mitogen-Activated Protein Kinases; C090942:4-(4-fluorophenyl)-2-(4-hydroxyphenyl)-5-(4-pyridyl)imidazole