title: Activation of p38 mitogen-activated protein kinase is necessary for gemcitabine-induced cytotoxicity in human pancreatic cancer cells.
abstract: BACKGROUND
  Gemcitabine is a pyrimidine nucleoside analog that is clinically active against pancreatic cancer. We have recently demonstrated that p38 MAPK is specifically activated by gemcitabine and that pharmacological blockade of p38 MAPK signaling prevented gemcitabine-induced apoptosis in human pancreatic cancer cells. In this study, we further investigated the implication of p38 MAPK in the cytotoxic action of gemcitabine.
  
  
  METHODS
  Cells expressing a dominant-negative mutant of p38 MAPK were generated. Clonogenic assays were used to assess the long-term effect on cancer cell viability in the human pancreatic cancer cells, PK1 and PCI43. The p38 MAPK activation level was assessed using an antibody specific to the phosphorylated form.
  
  
  RESULTS
  Gemcitabine increased the activation level of p38 MAPK in a dose-dependent manner and induced apoptosis in the two tested human pancreatic cancer cell lines. The selective p38 MAPK inhibitors, SB203580 and SB202190, reduced gemcitabine-induced activation of p38 MAPK, prevented the gemcitabine-induced apoptosis and increased long-term clonogenic survival. Overexpression of a dominant-negative p38 mutant in cells resulted in the reduction of gemcitabine-induced p38 MAPK activation and apoptosis, and increases in clonogenic survival.
  
  
  CONCLUSIONS
  These results strongly suggest that the activation of p38 MAPK signaling is necessary for gemcitabine-induced cell death in human pancreatic cancer cells. Based upon these results, we suggest that molecules of p38 MAPK signaling pathways should be listed as novel targets for gemcitabine-based therapy.
authors.affiliation: Third Department of Internal Medicine, Asahikawa Medical College, Asahikawa, Hokkaido, Japan.
authors.forename: Kazuya
authors.initials: K
authors.lastname: Koizumi
authors.forename: Satoshi
authors.initials: S
authors.lastname: Tanno
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Nakano
authors.forename: Atsuya
authors.initials: A
authors.lastname: Habiro
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Izawa
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Mizukami
authors.forename: Toshikatsu
authors.initials: T
authors.lastname: Okumura
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Kohgo
mesh_terms: D000230:Adenocarcinoma / Q000188:drug therapy* / Q000201:enzymology*; D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology*; D045744:Cell Line, Tumor; D003841:Deoxycytidine / Q000031:analogs & derivatives* / Q000037:antagonists & inhibitors / Q000494:pharmacology; D004347:Drug Interactions; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D010190:Pancreatic Neoplasms / Q000188:drug therapy* / Q000201:enzymology*; D011725:Pyridines / Q000494:pharmacology; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000093542:Gemcitabine
chemical_list: D000964:Antimetabolites, Antineoplastic; D004791:Enzyme Inhibitors; D007093:Imidazoles; D011725:Pyridines; D003841:Deoxycytidine; D048051:p38 Mitogen-Activated Protein Kinases; C093642:SB 203580; C090942:4-(4-fluorophenyl)-2-(4-hydroxyphenyl)-5-(4-pyridyl)imidazole; D000093542:Gemcitabine