title: Thymoquinone Pretreatment Overcomes the Insensitivity and Potentiates the Antitumor Effect of Gemcitabine Through Abrogation of Notch1, PI3K/Akt/mTOR Regulated Signaling Pathways in Pancreatic Cancer.
abstract: BACKGROUND
  The gemcitabine-insensitivity remains the main challenge for pancreatic cancer treatment. Thymoquinone, the predominant bioactive ingredient of Nigella sativa, has been shown to possess promising anti-cancer and chemo-sensitizing effects on pancreatic cancer, however, its meticulous mechanism is still indistinct.
  
  
  OBJECTIVE
  The objective of the present study was to investigate the potency of thymoquinone in combination with gemcitabine in inducing apoptosis and preventing the development of gemcitabine-insensitivity in pancreatic cancer cells.
  
  
  METHODS
  The anti-tumor effects of thymoquinone and gemcitabine were analyzed via evaluation of alterations of cell viability, tumor weight, apoptosis-related proteins, caspase-3, -9 activities and NF-κB DNA binding activity in pancreatic cancer cells in vitro and PANC-1 cells orthotopic xenograft in vivo.
  
  
  RESULTS
  Thymoquinone pretreatment following gemcitabine treatment synergistically caused an increase in pancreatic cancer cells apoptosis and tumor growth inhibition both in vitro and in vivo. The novel combinational regimen also contributes to alterations of multiple molecular signaling targets, such as the suppression of Notch1, NICD accompanying with up-regulation of PTEN, the inactivation of Akt/mTOR/S6 signaling pathways, and the suppression of phosphorylation and nuclear translocation of p65 induced by TNF-α. Thymoquinone pretreatment and gemcitabine also induced down-regulation of anti-apoptotic Bcl-2, Bcl-xL, XIAP and up-regulation and activation of pro-apoptotic molecules including Caspase-3, Caspase-9, Bax and increased release of cytochrome c.
  
  
  CONCLUSIONS
  This novel modality of thymoquinone pretreatment can enhance the anti-cancer activity of gemcitabine and may be a promising option in the treatment of pancreatic cancer.
authors.affiliation: Department of Gastroenterology, Renmin Hospital of Wuhan University, Wuhan, 430060, Hubei Province, People's Republic of China, muganggang@yahoo.com.
authors.forename: Gang-Gang
authors.initials: GG
authors.lastname: Mu
authors.forename: Ling-Li
authors.initials: LL
authors.lastname: Zhang
authors.forename: Hong-Yan
authors.initials: HY
authors.lastname: Li
authors.forename: Yan
authors.initials: Y
authors.lastname: Liao
authors.forename: Hong-Gang
authors.initials: HG
authors.lastname: Yu
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology / Q000627:therapeutic use*; D016227:Benzoquinones / Q000494:pharmacology / Q000627:therapeutic use*; D045744:Cell Line, Tumor; D003841:Deoxycytidine / Q000031:analogs & derivatives* / Q000627:therapeutic use; D019008:Drug Resistance, Neoplasm / Q000187:drug effects*; D004357:Drug Synergism; D005260:Female; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D031881:Nigella sativa; D010190:Pancreatic Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D008517:Phytotherapy; D010936:Plant Extracts / Q000494:pharmacology / Q000627:therapeutic use; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D051881:Receptor, Notch1 / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism; D023041:Xenograft Model Antitumor Assays; D000093542:Gemcitabine
chemical_list: D000970:Antineoplastic Agents; D016227:Benzoquinones; D003841:Deoxycytidine; D019869:Phosphatidylinositol 3-Kinases; D010936:Plant Extracts; D051057:Proto-Oncogene Proteins c-akt; D051881:Receptor, Notch1; D058570:TOR Serine-Threonine Kinases; D000093542:Gemcitabine; C497761:NOTCH1 protein, human; C546842:MTOR protein, human; C003466:thymoquinone