1,25-dihydroxyvitamin D3 transcriptionally represses p45Skp2 expression via the Sp1 sites in human prostate cancer cells

J Cell Physiol. 2006 Nov;209(2):363-9. doi: 10.1002/jcp.20741.


Upregulation of p27Kip1 protein in 1,25-dihydroxyvitamin D3-treated cancer cells is mediated via enhancement of gene transcription and reduction of protein degradation. 1,25-dihydroxyvitamin D3 inhibits the expression of p45Skp2, the F-box protein which is implicated in p27Kip1 degradation, to reduce turnover of p27Kip1 protein. In this study, we elucidate the underlying mechanism by which 1,25-dihydroxyvitamin D3 inhibits p45Skp2 in human LNCaP prostate cancer cells. Western blot and RT-PCR analysis suggest that 1,25-dihydroxyvitamin D3 suppresses p45Skp2 via transcriptional repression. Promoter activity assays indicate that 1,25-dihydroxyvitamin D3 directly inhibits p45Skp2 promoter activity. Deletion analysis shows that 1,25-dihydroxyvitamin D3 response element is localized at -447/-291 bp region from the translational start site of the p45Skp2 promoter. Mutation analysis suggests that two Sp1 sites localized at -386/-380 and -309/-294 bp region are required for transcriptional repression. Chromatin immunoprecipitation (CHIP) assay demonstrates that VDR indirectly binds to these Sp1 sites in vivo and this binding is increased after 1,25-dihydroxyvitamin D3 treatment. Re-CHIP assay suggests that VDR and Sp1 form a complex to bind to the Sp1 sites. DNA affinity precipitation assay (DAPA) shows that histone deacetylase 1 (HDAC1) is recruited to the Sp1 sites after 1,25-dihydroxyvitamin D3 stimulation. Re-CHIP assay verifies that binding of Sp1 and HDAC1 to p45Skp2 promoter is enhanced after 1,25-dihydroxyvitamin D3 treatment. HDAC inhibitor trichostatin A (TSA) reverses the inhibition of p45Skp2 promoter activity by 1,25-dihydroxyvitamin D3. Collectively, our results suggest that 1,25-dihydroxyvitamin D3 induces the formation of VDR/Sp1 complex and acts via a Sp1- and HDAC1-depedent pathway to inhibit p45Skp2 transcription.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 5' Untranslated Regions / genetics
  • Base Sequence
  • Binding Sites / drug effects
  • Calcitriol / pharmacology*
  • Dose-Response Relationship, Drug
  • Gene Expression Regulation, Neoplastic / drug effects
  • Histone Deacetylase 1
  • Histone Deacetylases / metabolism
  • Humans
  • Male
  • Molecular Sequence Data
  • Mutation / genetics
  • Promoter Regions, Genetic / drug effects
  • Prostatic Neoplasms / pathology*
  • Protein Binding / drug effects
  • Receptors, Calcitriol / metabolism
  • S-Phase Kinase-Associated Proteins / genetics
  • S-Phase Kinase-Associated Proteins / metabolism*
  • Sp1 Transcription Factor / metabolism*
  • Time Factors
  • Transcription, Genetic / drug effects*
  • Tumor Cells, Cultured


  • 5' Untranslated Regions
  • Receptors, Calcitriol
  • S-Phase Kinase-Associated Proteins
  • Sp1 Transcription Factor
  • HDAC1 protein, human
  • Histone Deacetylase 1
  • Histone Deacetylases
  • Calcitriol