title: Novel levamisole derivative induces extrinsic pathway of apoptosis in cancer cells and inhibits tumor progression in mice.
abstract: BACKGROUND
  Levamisole, an imidazo(2,1-b)thiazole derivative, has been reported to be a potential antitumor agent. In the present study, we have investigated the mechanism of action of one of the recently identified analogues, 4a (2-benzyl-6-(4'-fluorophenyl)-5-thiocyanato-imidazo[2,1-b][1], [3], [4]thiadiazole).
  
  
  METHODS
  ROS production and expression of various apoptotic proteins were measured following 4a treatment in leukemia cell lines. Tumor animal models were used to evaluate the effect of 4a in comparison with Levamisole on progression of breast adenocarcinoma and survival. Immunohistochemistry and western blotting studies were performed to understand the mechanism of 4a action both ex vivo and in vivo.
  
  
  RESULTS
  We have determined the IC(50) value of 4a in many leukemic and breast cancer cell lines and found CEM cells most sensitive (IC(50) 5 µM). Results showed that 4a treatment leads to the accumulation of ROS. Western blot analysis showed upregulation of pro-apoptotic proteins t-BID and BAX, upon treatment with 4a. Besides, dose-dependent activation of p53 along with FAS, FAS-L, and cleavage of CASPASE-8 suggest that it induces death receptor mediated apoptotic pathway in CEM cells. More importantly, we observed a reduction in tumor growth and significant increase in survival upon oral administration of 4a (20 mg/kg, six doses) in mice. In comparison, 4a was found to be more potent than its parental analogue Levamisole based on both ex vivo and in vivo studies. Further, immunohistochemistry and western blotting studies indicate that 4a treatment led to abrogation of tumor cell proliferation and activation of apoptosis by the extrinsic pathway even in animal models.
  
  
  CONCLUSIONS
  Thus, our results suggest that 4a could be used as a potent chemotherapeutic agent.
authors.affiliation: Department of Biochemistry, Indian Institute of Science, Bangalore, Karnataka, India.
authors.forename: Mahesh
authors.initials: M
authors.lastname: Hegde
authors.forename: Subhas S
authors.initials: SS
authors.lastname: Karki
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Thomas
authors.forename: Sujeet
authors.initials: S
authors.lastname: Kumar
authors.forename: Kuppusamy
authors.initials: K
authors.lastname: Panjamurthy
authors.forename: Somasagara R
authors.initials: SR
authors.lastname: Ranganatha
authors.forename: Kanchugarakoppal S
authors.initials: KS
authors.lastname: Rangappa
authors.forename: Bibha
authors.initials: B
authors.lastname: Choudhary
authors.forename: Sathees C
authors.initials: SC
authors.lastname: Raghavan
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D014408:Biomarkers, Tumor / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D004249:DNA Damage; D018450:Disease Progression; D004305:Dose-Response Relationship, Drug; D004354:Drug Screening Assays, Antitumor; D006801:Humans; D007938:Leukemia / Q000188:drug therapy / Q000473:pathology; D007978:Levamisole / Q000009:adverse effects / Q000031:analogs & derivatives* / Q000494:pharmacology* / Q000627:therapeutic use; D051379:Mice; D008954:Models, Biological; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*
chemical_list: D014408:Biomarkers, Tumor; D017382:Reactive Oxygen Species; D007978:Levamisole