title: Bortezomib-induced apoptosis in cultured pancreatic cancer cells is associated with ceramide production.
abstract: OBJECTIVE
  The proteasome inhibitor bortezomib (PS-341) has displayed significant efficiency against pancreatic cancer cells. However, the underlying mechanisms are not fully understood. Here, we tested if ceramide production was involved in the bortezomib's effect.
  
  
  METHODS
  Two transformed pancreatic cancer cell lines (PANC-1 and Mia) and the primary pancreatic cancer cells were used. Cell death was analyzed by MTT viability assay and trypan blue staining. Cell apoptosis was analyzed by Histone DNA-ELISA assay and Annexin V FACS. Western blots were used to test signal protein changes. The cellular ceramide level after bortezomib treatment was also determined.
  
  
  RESULTS
  In cultured pancreatic cancer cells, bortezomib increased cellular ceramide production to promote cell apoptosis. The ceramide de novo synthase inhibitor fumonisin B1 (F-B1) suppressed bortezomib-induced ceramide production and apoptosis, while exogenously added C6-ceramide facilitated bortezomib-induced pancreatic cancer cell death. Meanwhile, 1-phenyl-2-decanoylamino-3-morpholino-1-propanol (PDMP), the inhibitor of glucosylceramide synthetase as well as the sphingosine kinase 1 inhibitors (SKI-II and SKI-IV), facilitated bortezomib-induced ceramide production and subsequent cell apoptosis. Further, bortezomib-induced pro-apoptotic c-Jun N-terminal kinase (JNK) activation was also associated with ceramide production. JNK activation by bortezomib was suppressed by F-B1, but was enhanced by SKI-II and PDMP in pancreatic cancer cells. Finally, C6-ceramide, SKI-II, and PDMP dramatically enhanced bortezomib-induced cytotoxicity in primary cultured pancreatic cancer cells.
  
  
  CONCLUSIONS
  We found that bortezomib-induced apoptosis was associated with ceramide production in primary and transformed pancreatic cancer cells.
authors.affiliation: Department of Gastroenterology, Wuxi No. 2 People's Hospital, Wuxi, Jiangsu, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Gong
authors.forename: Bo
authors.initials: B
authors.lastname: Yang
authors.forename: Ming
authors.initials: M
authors.lastname: Xu
authors.forename: Bo
authors.initials: B
authors.lastname: Cheng
authors.forename: Xuejun
authors.initials: X
authors.lastname: Tang
authors.forename: Ping
authors.initials: P
authors.lastname: Zheng
authors.forename: Yan
authors.initials: Y
authors.lastname: Jing
authors.forename: Gao-jue
authors.initials: GJ
authors.lastname: Wu
mesh_terms: D000970:Antineoplastic Agents / Q000627:therapeutic use*; D017209:Apoptosis / Q000187:drug effects*; D001897:Boronic Acids / Q000494:pharmacology*; D000069286:Bortezomib; D045744:Cell Line, Tumor; D002518:Ceramides / Q000096:biosynthesis*; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D048848:MAP Kinase Kinase Kinase 5 / Q000502:physiology; D009025:Morpholines / Q000494:pharmacology; D010190:Pancreatic Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000037:antagonists & inhibitors; D011719:Pyrazines / Q000494:pharmacology*; D000099157:Sphingosine Kinase
chemical_list: D000970:Antineoplastic Agents; D001897:Boronic Acids; D000069286:Bortezomib; D002518:Ceramides; D048031:JNK Mitogen-Activated Protein Kinases; D048848:MAP Kinase Kinase Kinase 5; D009025:Morpholines; D017853:Phosphotransferases (Alcohol Group Acceptor); D011719:Pyrazines; D000099157:Sphingosine Kinase; C033110:RV 538; C482858:MAP3K5 protein, human