TGF-beta is not involved in early phase growth inhibition of keratinocytes by 1alpha,25(OH)2vitamin D3

J Dermatol Sci. 2004 Oct;36(1):41-50. doi: 10.1016/j.jdermsci.2004.07.002.

Abstract

Background: It has been proposed that transforming growth factor-beta (TGF-beta) is involved in the growth inhibition of normal human epidermal keratinocytes (NHEK) by 1alpha,25-dihydoxyvitamin D(3) (1alpha,25(OH)(2)D(3)), although this is still controversial because of the difficulty in blocking TGF-beta activity completely.

Objective: To determine whether TGF-beta is involved in early phase growth inhibition by 1alpha,25(OH)(2)D(3).

Methods: TGF-beta mRNA was detected by ribonuclease protection assay (RPA), and biological active TGF-beta was determined by a luciferase reporter assay. To block intrinsic TGF-beta activity completely, we constructed an adenovirus vector expressing a truncated TGF-beta type II receptor with a dominant negative effect (AdexTbetaTR) that blocks TGF-beta signal transduction.

Results: 1alpha,25(OH)(2)D(3) slightly upregulated TGF-beta1 and TGF-beta2 after 24 h according to an RPA and a luciferase reporter assay, however growth inhibition by 1alpha,25(OH)(2)D(3) occurred at 6 h. The addition of 10(-6) M of 1alpha,25(OH)(2)D(3) to NHEK infected with AdexTbetaTR or AdexLacZ (control vector) reduced DNA synthesis to 59.3 and 62.2% at 6 h, respectively. There was no significant difference in cell number after a 3-day incubation with AdexTbetaTR or AdexLacZ-infected cells treated with 1alpha,25(OH)(2)D(3).

Conclusion: Since 1alpha,25(OH)(2)D(3) rapidly inhibits NHEK growth regardless of the prevention of TGF-beta signal transduction, TGF-beta is not involved in early phase growth inhibition by 1alpha,25(OH)(2)D(3).

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenoviridae / genetics
  • Blotting, Western
  • Bromodeoxyuridine / pharmacology
  • Calcitriol / pharmacology*
  • Cell Cycle
  • Cell Proliferation
  • Cells, Cultured
  • Genes, Dominant
  • Humans
  • Keratinocytes / cytology
  • Keratinocytes / metabolism*
  • Luciferases / metabolism
  • Protein Serine-Threonine Kinases
  • RNA, Messenger / metabolism
  • Receptor, Transforming Growth Factor-beta Type II
  • Receptors, Transforming Growth Factor beta / chemistry
  • Ribonucleases / metabolism
  • Time Factors
  • Transforming Growth Factor beta / biosynthesis*
  • Transforming Growth Factor beta / metabolism
  • Transforming Growth Factor beta / physiology*
  • Transforming Growth Factor beta1
  • Transforming Growth Factor beta2
  • Up-Regulation

Substances

  • RNA, Messenger
  • Receptors, Transforming Growth Factor beta
  • TGFB1 protein, human
  • TGFB2 protein, human
  • Transforming Growth Factor beta
  • Transforming Growth Factor beta1
  • Transforming Growth Factor beta2
  • Luciferases
  • Protein Serine-Threonine Kinases
  • Receptor, Transforming Growth Factor-beta Type II
  • Ribonucleases
  • Calcitriol
  • Bromodeoxyuridine