title: [Experimental studies on treatment of nasopharyngeal carcinoma with combination regimen of hydroxycamptothecin and etoposide].
abstract: OBJECTIVE
  Many studies showed that there is complementary effect between topoisomerase I inhibitor and topoisomerase II inhibitor. Combination of them showed synergistic action. This study was designed to investigate the experimental therapeutic effect of the combination of topoisomerase I inhibitor hydroxycamptothecin (HCPT) with topoisomerase II inhibitor etoposide (VP-16) on nasopharyngeal carcinoma (NPC), the effect of the combination of HCPT with VP-16 against NPC was studied in vitro and in vivo.
  
  
  METHODS
  Cytotoxicity of HCPT alone, VP-16 alone, and combination of HCPT and VP-16 on NPC cell strain CNE2 were measured by MTT assay. The models of nude mice xenografts were established for investigating the effect of the combination regimen against NPC in vivo.
  
  
  RESULTS
  HCPT alone and VP-16 alone have potent cytotoxicity to CNE2 cells. The IC(50) values were 13.5+/-1.2 micromol/L and 13.5+/-1.0 micromol/L, respectively. The combination of HCPT with VP-16 (1:1) showed synergistic cytotoxicity to CNE2 cells in vitro (CI< 1). In vivo experiment showed that HCPT alone (1.5 mg/kg, i.p., q2d) exhibited 13.6% inhibition growth rate;VP-16 alone (10 mg/kg, i.p., q2d) exhibited 27.3% inhibition growth rate; the combination regimen exhibited 50% inhibition growth rate.
  
  
  CONCLUSIONS
  The combination of HCPT with VP-16 had significant synergistic effect against NPC in vitro and in vivo. These results suggested that the combination of HCPT with VP-16 is a promising regimen to treat NPC in clinic.
authors.affiliation: Cancer Center,Sun Yat-sen University, Guangzhou, Guangdong, PR China.
authors.forename: Yong-Ju
authors.initials: YJ
authors.lastname: Liang
authors.forename: Li-Wu
authors.initials: LW
authors.lastname: Fu
authors.forename: Yan
authors.initials: Y
authors.lastname: Ding
authors.forename: Hui-Yu
authors.initials: HY
authors.lastname: Xiong
authors.forename: Li-Ming
authors.initials: LM
authors.lastname: Chen
authors.forename: Xiao-Ping
authors.initials: XP
authors.lastname: Yang
authors.forename: Qi-Chao
authors.initials: QC
authors.lastname: Pan
mesh_terms: D000818:Animals; D000972:Antineoplastic Agents, Phytogenic / Q000008:administration & dosage; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D002166:Camptothecin / Q000008:administration & dosage / Q000031:analogs & derivatives*; D002470:Cell Survival / Q000187:drug effects; D004195:Disease Models, Animal; D019008:Drug Resistance, Neoplasm; D005047:Etoposide / Q000008:administration & dosage; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D009303:Nasopharyngeal Neoplasms / Q000473:pathology; D009368:Neoplasm Transplantation; D009374:Neoplasms, Experimental / Q000188:drug therapy*; D059004:Topoisomerase I Inhibitors; D014407:Tumor Cells, Cultured; D023041:Xenograft Model Antitumor Assays
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D059004:Topoisomerase I Inhibitors; D005047:Etoposide; C028098:10-hydroxycamptothecin; D002166:Camptothecin