Gamma-tocotrienol Modulation of Senescence-Associated Gene Expression Prevents Cellular Aging in Human Diploid Fibroblasts

Clinics (Sao Paulo). 2012;67(2):135-43. doi: 10.6061/clinics/2012(02)08.

Abstract

Objective: Human diploid fibroblasts undergo a limited number of cellular divisions in culture and progressively reach a state of irreversible growth arrest, a process termed cellular aging. The beneficial effects of vitamin E in aging have been established, but studies to determine the mechanisms of these effects are ongoing. This study determined the molecular mechanism of γ-tocotrienol, a vitamin E homolog, in the prevention of cellular aging in human diploid fibroblasts using the expression of senescence-associated genes.

Methods: Primary cultures of young, pre-senescent, and senescent fibroblast cells were incubated with γ-tocotrienol for 24 h. The expression levels of ELN, COL1A1, MMP1, CCND1, RB1, and IL6 genes were determined using the quantitative real-time polymerase chain reaction. Cell cycle profiles were determined using a FACSCalibur Flow Cytometer.

Results: The cell cycle was arrested in the G(0)/G(1) phase, and the percentage of cells in S phase decreased with senescence. CCND1, RB1, MMP1, and IL6 were upregulated in senescent fibroblasts. A similar upregulation was not observed in young cells. Incubation with γ-tocotrienol decreased CCND1 and RB1 expression in senescent fibroblasts, decreased cell populations in the G(0)/G(1) phase and increased cell populations in the G(2)/M phase. γ-Tocotrienol treatment also upregulated ELN and COL1A1 and downregulated MMP1 and IL6 expression in young and senescent fibroblasts.

Conclusion: γ-Tocotrienol prevented cellular aging in human diploid fibroblasts, which was indicated by the modulation of the cell cycle profile and senescence-associated gene expression.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Analysis of Variance
  • Antioxidants / pharmacology*
  • Biomarkers / analysis
  • Cell Cycle / drug effects*
  • Cell Cycle / genetics
  • Cells, Cultured
  • Cellular Senescence / drug effects*
  • Cellular Senescence / genetics
  • Chromans / pharmacology*
  • Collagen Type I / genetics
  • Collagen Type I / metabolism
  • Cyclin D1 / genetics
  • Cyclin D1 / metabolism
  • Diploidy
  • Fibroblasts / cytology
  • Fibroblasts / drug effects*
  • Fibroblasts / metabolism
  • Humans
  • Interleukin-6 / genetics
  • Interleukin-6 / metabolism
  • Matrix Metalloproteinase 1 / genetics
  • Matrix Metalloproteinase 1 / metabolism
  • RNA, Messenger / metabolism
  • Retinoblastoma Protein / genetics
  • Retinoblastoma Protein / metabolism
  • Up-Regulation / drug effects
  • Vitamin E / analogs & derivatives*
  • Vitamin E / pharmacology
  • beta-Galactosidase / analysis*
  • beta-Galactosidase / metabolism

Substances

  • Antioxidants
  • Biomarkers
  • CCND1 protein, human
  • Chromans
  • Collagen Type I
  • Interleukin-6
  • RNA, Messenger
  • Retinoblastoma Protein
  • collagen type I, alpha 1 chain
  • Cyclin D1
  • Vitamin E
  • plastochromanol 8
  • beta-Galactosidase
  • MMP1 protein, human
  • Matrix Metalloproteinase 1