title: pERK1/2 silencing sensitizes pancreatic cancer BXPC-3 cell to gemcitabine-induced apoptosis via regulating Bax and Bcl-2 expression.
abstract: BACKGROUND
  Our previous study has demonstrated that knockdown of activated ERK1/2(pERK1/2) sensitizes pancreatic cancer cells to chemotherapeutic drug gemcitabine (Gem) treatment. However, the details of this survival mechanism remain undefined. It has also shown that Bcl-2 confers resistance and Bax sensitizes to gemcitabine-induced apoptosis in pancreatic cancer cells. Furthermore, the extracellular signaling-regulated kinase (ERK) signaling pathway regulates Bcl-2/Bax expression ratio. We therefore tested the hypothesis that pancreatic cancer cells are resistant to gemcitabine and this resistance is due to activation of ERK1/2 and subsequent upregulation of Bcl-2 and downregulation of Bax.
  
  
  METHODS
  Pancreatic cancer cell BXPC-3 was used in the study. The effect of pharmacological inhibition of ERK1/2 on resistance of pancreatic cancer cells to apoptosis induced by treatment with gemcitabine was analyzed. The following methods were utilized: TUNEL and ELISA were used to detect apoptosis. Western blot was used to detect the protein expression.
  
  
  RESULTS
  Gemcitabine treatment enhanced the activity of ERK1/2 in the BXPC-3 cells. Inhibition of the ERK1/2 by PD98059 could downregulate Bcl-2 and upregulate Bax and was associated with restoration of sensitivity to gemcitabine in BXPC-3 cells. Depletion of endogenous Bcl-2 expression by specific small interfering RNA transfection significantly increased gemcitabine-induced cell apoptosis. Combined treatment with PD98059 and Bax siRNA transfection could decrease gemcitabine-induced ERK1/2 and Bax activation, which subsequently resulted in decreased apoptosis.
  
  
  CONCLUSIONS
  The upregulation of ERK1/2-dependent Bcl-2 and downregulation of ERK1/2-dependent Bax can protect human pancreatic cancer cells from gemcitabine-induced apoptosis. Targeting the ERK1/2-Bax/Bcl-2 pathway may in part lead to sensitization of pancreatic cancer to gemcitabine.
authors.affiliation: Department of Clinical Laboratory, People's Hospital of Laiwu, Laiwu, Shangdong, China. wangminjyk@126.com.
authors.forename: Min
authors.initials: M
authors.lastname: Wang
authors.affiliation: Department of Internal Neurology, People's Hospital of Zhangqiu, ZhangQiu, Shangdong, China. luxj08@163.com.
authors.forename: Xingjiao
authors.initials: X
authors.lastname: Lu
authors.affiliation: Department of Clinical Laboratory, People's Hospital of Laiwu, Laiwu, Shangdong, China. dongxgwf@yeah.net.
authors.forename: Xueguang
authors.initials: X
authors.lastname: Dong
authors.affiliation: Department of General Surgery, The Affiliated Hospital of Qingdao University, Qingdao, China. cancerhly@163.com.|Department of Clinical Laboratory, People's Hospital of Weifang, Weifang, Shangdong, China. cancerhly@163.com.
authors.forename: Fengyun
authors.initials: F
authors.lastname: Hao
authors.affiliation: Department of Clinical Laboratory, People's Hospital of Laiwu, Laiwu, Shangdong, China. qyfylzm@126.com.|Department of General Surgery, The Affiliated Hospital of Qingdao University, Qingdao, China. qyfylzm@126.com.
authors.forename: Zimin
authors.initials: Z
authors.lastname: Liu
authors.affiliation: Department of Clinical Laboratory, People's Hospital of Weifang, Weifang, Shangdong, China. zhangyong2013226@126.com.
authors.forename: Guangzhen
authors.initials: G
authors.lastname: Ni
authors.affiliation: Department of General Surgery, The Affiliated Hospital of Qingdao University, Qingdao, China. chendd820@126.com.
authors.forename: Dong
authors.initials: D
authors.lastname: Chen
mesh_terms: D000230:Adenocarcinoma / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D049109:Cell Proliferation / Q000187:drug effects; D003841:Deoxycytidine / Q000031:analogs & derivatives* / Q000494:pharmacology; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D006801:Humans; D019950:Mitogen-Activated Protein Kinase 1 / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D010190:Pancreatic Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology*; D010766:Phosphorylation / Q000187:drug effects; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics; D014407:Tumor Cells, Cultured; D051028:bcl-2-Associated X Protein / Q000378:metabolism*; D000093542:Gemcitabine
chemical_list: D000964:Antimetabolites, Antineoplastic; C494826:BAX protein, human; D019253:Proto-Oncogene Proteins c-bcl-2; D034741:RNA, Small Interfering; D051028:bcl-2-Associated X Protein; D003841:Deoxycytidine; C535150:MAPK1 protein, human; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D000093542:Gemcitabine