title: Antitumor activity of novel indirubin derivatives in rat tumor model.
abstract: OBJECTIVE
  The novel indirubin derivatives 5'-nitro-indirubinoxime, 5'-fluoro-indirubinoxime, and 5'-trimethylacetamino-indirubinoxime were designed and tested for antitumor activity both in vitro and in vivo using rat tumor model.
  
  
  METHODS
  Three-week-old male Sprague-Dawley rats were inoculated s.c. on the left flank with 10(7) RK3E-ras rat kidney epithelial cells harboring k-ras gene. Alternatively, 5 x 10(6) RK3E-ras cells were injected into the oral mucosa. Indirubin derivative treatment began on the 3rd or 6th day after oral or s.c. cell injection, respectively. Indirubin derivatives were directly injected into the tumor every other day for a total of five times. Animals were monitored daily and tumor volume was measured by caliper.
  
  
  RESULTS
  Indirubin derivatives showed potent antiproliferative activity on various human cancer cells and oncogenic RK3E-ras rat kidney cells, with IC(50) ranging from 1 to 12 mumol/L. Treatment with indirubin derivatives induced the activation of caspase-7 followed by apoptosis in RK3E-ras cells. Indirubin derivatives showed strong antitumor activity in rat solid and oral tumor models. Direct injection of indirubin derivatives every other day for 10 days induced significant inhibition of tumor growth in Sprague-Dawley rats bearing RK3E-ras-induced tumors. Histologically, treatment with indirubin derivatives caused significant inhibition of tumor formation with increased apoptosis and decreased tumor cell proliferation.
  
  
  CONCLUSIONS
  Our data showed that novel indirubin derivatives 5'-nitro-indirubinoxime, 5'-fluoro-indirubinoxime, and 5'-trimethylacetamino-indirubinoxime effectively arrested the tumor growth by inhibiting cell proliferation and inducing apoptosis. These findings provide the potential value of indirubin derivatives as novel candidates for antitumor agents.
authors.affiliation: Department of Biochemistry, Dongguk University College of Oriental Medicine, Kyungju, South Korea.
authors.forename: Soo-A
authors.initials: SA
authors.lastname: Kim
authors.forename: Yong-Chul
authors.initials: YC
authors.lastname: Kim
authors.forename: Si-Wouk
authors.initials: SW
authors.lastname: Kim
authors.forename: Sang-Ho
authors.initials: SH
authors.lastname: Lee
authors.forename: Jung-Joon
authors.initials: JJ
authors.lastname: Min
authors.forename: Sang-Gun
authors.initials: SG
authors.lastname: Ahn
authors.forename: Jung-Hoon
authors.initials: JH
authors.lastname: Yoon
mesh_terms: D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000494:pharmacology*; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis; D053148:Caspase 3 / Q000378:metabolism; D045744:Cell Line, Tumor; D004195:Disease Models, Animal; D004354:Drug Screening Assays, Antitumor; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D020128:Inhibitory Concentration 50; D008297:Male; D009368:Neoplasm Transplantation; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D000903:Antibiotics, Antineoplastic; D000970:Antineoplastic Agents; D007211:Indoles; D053148:Caspase 3; C027185:indirubin