title: COX-2-independent induction of apoptosis by celecoxib and polyamine naphthalimide conjugate mediated by polyamine depression in colorectal cancer cell lines.
abstract: BACKGROUND
  Polyamine metabolism is an intriguing tumor therapeutic target. The present study was designed to assess the synergistic antitumor effects of NPC-16, a novel polyamine naphthalimide conjugate, with celecoxib and to elucidate the mechanism of these effects on human colorectal cancer cells.
  
  
  METHODS
  Cell proliferation was assessed by the MTT assay. Cell apoptosis and mitochondria membrane potential were evaluated by high content screening analysis. Intracellular polyamine content was detected by HPLC. Protein expression was detected by western blot analysis.
  
  
  RESULTS
  The co-treatment with celecoxib enhanced NPC-16-induced apoptosis in HCT116 (COX-2 no expression), HT29 (COX-2 higher expression) and Caco-2 (COX-2 higher expression) colorectal cancer cells, which was mediated by the elevated NPC-16 uptake via the effect of celecoxib on polyamine metabolism, including the up-regulated spermidine/spermine N(1)-acetyltransferase (SSAT) activity and reduced intracellular polyamine levels. The presence of celecoxib does not result in obviously different effect on the NPC-16-triggered apoptosis in diverse COX-2 expressed colorectal cell lines, suggesting that COX-2 was not one vital factor in the apoptotic mechanism. Furthermore, this synergistic apoptosis was involved in the PKB/AKT signal pathway, Bcl-2 and caspase family members. Z-VAD-FMK, a cell permeable pan caspase inhibitor, almost completely inhibited celecoxib and NPC-16 co-induced apoptosis, indicating that this apoptosis was caspase dependent.
  
  
  CONCLUSIONS
  Co-treatment of celecoxib and NPC-16 could induce colorectal cancer cell apoptosis via COX-2-independent and caspase-dependent mechanisms. The combination therapy with these agents might provide a novel therapeutic model for colorectal cancer.
authors.affiliation: Institute of Chemical Biology, Henan University, Kaifeng, China. wcjsxq@henu.edu.cn
authors.forename: Song-qiang
authors.initials: SQ
authors.lastname: Xie
authors.forename: Ya-hong
authors.initials: YH
authors.lastname: Zhang
authors.forename: Qian
authors.initials: Q
authors.lastname: Li
authors.forename: Jian-hong
authors.initials: JH
authors.lastname: Wang
authors.forename: Jing-hua
authors.initials: JH
authors.lastname: Li
authors.forename: Jin
authors.initials: J
authors.lastname: Zhao
authors.forename: Chao-jie
authors.initials: CJ
authors.lastname: Wang
mesh_terms: D000123:Acetyltransferases / Q000378:metabolism; D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D020169:Caspases / Q000378:metabolism; D000068579:Celecoxib; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D015179:Colorectal Neoplasms / Q000188:drug therapy / Q000201:enzymology* / Q000473:pathology*; D051546:Cyclooxygenase 2 / Q000378:metabolism*; D045304:Cytochromes c / Q000378:metabolism; D004357:Drug Synergism; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D053644:Naphthalimides / Q000737:chemistry / Q000494:pharmacology* / Q000627:therapeutic use; D011073:Polyamines / Q000378:metabolism* / Q000494:pharmacology / Q000627:therapeutic use; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D011720:Pyrazoles / Q000494:pharmacology* / Q000627:therapeutic use; D013449:Sulfonamides / Q000494:pharmacology* / Q000627:therapeutic use; D015854:Up-Regulation / Q000187:drug effects; D000099228:Diamine N-Acetyltransferase
chemical_list: D000123:Acetyltransferases; D000590:Amino Acid Chloromethyl Ketones; D020169:Caspases; D000068579:Celecoxib; D051546:Cyclooxygenase 2; D045304:Cytochromes c; D053644:Naphthalimides; D011073:Polyamines; D051057:Proto-Oncogene Proteins c-akt; D019253:Proto-Oncogene Proteins c-bcl-2; D011720:Pyrazoles; D013449:Sulfonamides; D000099228:Diamine N-Acetyltransferase; C559142:NPC 16; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; C496540:PTGS2 protein, human