title: Characterization of a novel curcumin analog P1 as potent inhibitor of the NF-κB signaling pathway with distinct mechanisms.
abstract: OBJECTIVE
  Curcumin has shown promising anticancer activity, which relies on its inhibition on NF-κB pathway. In this study, we characterized the pharmacological profile of a novel curcumin analog P1 and elucidate the related mechanisms.
  
  
  METHODS
  HEK293/NF-κB cells, stably transfected with an NF-κB-responsive luciferase reporter plasmid, were generated for high-throughput screen (HTS). Eight cancer cell lines, including PC3, COLO 205, HeLa cells etc. were tested. Cell viability was assessed using the sulforhodamine B (SRB) assays. Cell apoptosis was evaluated using FACS, immunocytochemistry, and Western blotting. H2-DCFDA and MitoSOX Red were used to detect cellular and mitochondrial reactive oxygen species (ROS). The mitochondrial function was evaluated using mitochondrial oxygen consumption assay.
  
  
  RESULTS
  P1, a tropinone curcumin, was found in HTS targeting the NF-κB pathway. Its IC50 value in inhibition of TNF-α-induced NF-κB activation was 0.8 μmol/L, whereas its IC50 values in inhibiting the growth of A549 and HeLa cells were 1.24 and 0.69 μmol/L, respectively, which was 20- to 30-fold more potent than curcumin. The inhibition of P1 on the NF-κB pathway was further addressed in HeLa cells. The compound up to 10 μmol/L did not affect the binding of NF-κB to DNA, but markedly inhibited NF-κB nuclear translocation, IκB degradation and IκB kinase phosphorylation. The compound (1 and 3 μmol/L) concentration-dependently induced ROS generation, whereas curcumin up to 20 μmol/L had no effect. P1-induced ROS generation was mainly localized in mitochondria, and reversed by NAC. Moreover, the compound significantly enhanced TNF-α-induced apoptosis.
  
  
  CONCLUSIONS
  P1 is a novel curcumin analog with potent anticancer activities, which exerts a distinct inhibition on the NF-κB pathway.
authors.affiliation: National Center for Drug Screening, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China.
authors.forename: Yan-min
authors.initials: YM
authors.lastname: Peng
authors.forename: Jian-bin
authors.initials: JB
authors.lastname: Zheng
authors.forename: Yu-bo
authors.initials: YB
authors.lastname: Zhou
authors.forename: Jia
authors.initials: J
authors.lastname: Li
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology; D045744:Cell Line, Tumor; D003474:Curcumin / Q000031:analogs & derivatives* / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D016328:NF-kappa B / Q000037:antagonists & inhibitors* / Q000378:metabolism / Q000502:physiology*; D011485:Protein Binding / Q000187:drug effects / Q000502:physiology; D015398:Signal Transduction / Q000187:drug effects* / Q000502:physiology; D014326:Tropanes / Q000494:pharmacology
chemical_list: D000970:Antineoplastic Agents; D016328:NF-kappa B; D014326:Tropanes; C016808:3-tropinone; D003474:Curcumin