Curcumin derivatives inhibit the formation of Jun-Fos-DNA complex independently of their conserved cysteine residues.
Curcumin, a major active component of turmeric, has been identified as an inhibitor of the transcriptional activity of activator protein-1 (AP-1). Recently, it was also found that curcumin and synthetic curcumin derivatives can inhibit the binding of Jun-Fos, which are the members of the AP-1 family, to DNA. However, the mechanism of this inhibition by curcumin and its derivatives was not disclosed. Since the binding of Jun-Fos dimer to DNA can be modulated by redox control involving conserved cysteine residues, we studied whether curcumin and its derivatives inhibit Jun-Fos DNA binding activity via these residues. However, the inhibitory mechanism of curcumin and its derivatives, unlike that of other Jun-Fos inhibitors, was found to be independent of these conserved cysteine residues. In addition, we investigated whether curcumin derivatives can inhibit AP-1 transcriptional activity in vivo using a luciferase assay. We found that, among the curcumin derivatives examined, only inhibitors shown to inhibit the binding of Jun-Fos to DNA by Electrophoretic Mobility Shift Assay (EMSA) inhibited AP-1 transcriptional activity in vivo. Moreover, RT-PCR revealed that curcumin derivatives, like curcumin, downregulated c-jun mRNA in JB6 cells. These results suggest that the suppression of the formation of DNA-Jun-Fos complex is the main cause of reduced AP-1 transcriptional activity by curcuminoids, and that EMSA is a suitable tool for identifying inhibitors of transcriptional activation.
Park
Chi Hoon
CH
Division of Chemistry and Molecular Engineering, Seoul National University, Seoul 151-742, Korea, chulyang@plaza.snu.ac.kr.
Lee
Ju Hyung
JH
Yang
Chu Hak
CH
D000818:Animals; D000970:Antineoplastic Agents / Q000737:chemistry / Q000494:pharmacology*; D017124:Conserved Sequence; D003474:Curcumin / Q000031:analogs & derivatives / Q000737:chemistry / Q000494:pharmacology*; D003545:Cysteine / Q000737:chemistry* / Q000235:genetics; D024202:Electrophoretic Mobility Shift Assay; D006801:Humans; D051379:Mice; D015394:Molecular Structure; D016760:Proto-Oncogene Proteins c-fos / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D016755:Proto-Oncogene Proteins c-jun / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D012045:Regulatory Sequences, Nucleic Acid; D018808:Transcription Factor AP-1 / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured / Q000187:drug effects
D000970:Antineoplastic Agents; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D018808:Transcription Factor AP-1; D003474:Curcumin; D003545:Cysteine