Tiron protects against UVB-induced senescence-like characteristics in human dermal fibroblasts by the inhibition of superoxide anion production and glutathione depletion.
OBJECTIVE
Free radicals and reactive oxygen species (ROS), which are generated by UV irradiation, may induce an irreversible growth arrest similar to senescence. Tiron, 4,5-dihydroxy-1,3-benzene disulfonic acid, is a widely used antioxidant to rescue ROS-evoked cell death. The aim of the article was to explore the effects of tiron on skin photoaging and associated mechanisms.


METHODS
The effects of tiron on cell proliferation were determined using 3-(4,5-dimethylthiazol-2-Yl)-2,5-diphenyltetrazolium bromide. Senescent cells were determined by morphology and senescence-associated β-galactosidase activity analysis. Intracellular hydrogen peroxide, superoxide anion and glutathione concentration were analysed by a fluorescent probe. The concomitant changes of protein expression were analysed with Western blot.


RESULTS
Human dermal fibroblasts were induced to premature senescence by sub-cytotoxic doses of irradiated UVB. Strong senescence-associated β-galactosidase activity and increased intracellular superoxide anion were observed in human dermal fibroblasts irradiated by UVB. Tiron blocks UVB-induced glutathione depletion and increase of superoxide anion and protects against UVB-induced senescence-like characteristics in human dermal fibroblasts. Compared with normal fibroblasts, UVB-irradiated human dermal fibroblasts showed a higher ratio of active (hypophosphorylated) to inactive (phosphorylated) forms of Rb and p38, upregulation of p53 or p16 and c-Myc and insulin-like growth factor 1 (IGF-1) downregulation. After treatment with tiron, p53, p16 c-Myc and IGF-1 as well as phosphorylation Rb and p38 could partially recover.


CONCLUSIONS
These results indicate that tiron protects against UVB-induced senescence-like characteristics in human dermal fibroblasts via the inhibition of production of superoxide anion and glutathione depletion, and modulation of related senescence proteins.
No.3 People's Hospital/Shanghai Jiao-Tong University School of Medicine (SJTU-SM), Shanghai, China.
Yong
Y
Fang
Xiao-Hui
XH
Hu
Zhi-Gang
ZG
Jia
Mang-Hua
MH
Xu
Zhu-Ying
ZY
Guo
Feng-Hou
FH
Gao
D014013:1,2-Dihydroxybenzene-3,5-Disulfonic Acid Disodium Salt / Q000494:pharmacology*; D000975:Antioxidants / Q000494:pharmacology*; D017209:Apoptosis; D049109:Cell Proliferation; D002470:Cell Survival; D002478:Cells, Cultured; D016922:Cellular Senescence / Q000187:drug effects*; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000378:metabolism; D005347:Fibroblasts / Q000378:metabolism / Q000473:pathology; D005978:Glutathione / Q000378:metabolism; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D016271:Proto-Oncogene Proteins c-myc / Q000378:metabolism; D016160:Retinoblastoma Protein / Q000378:metabolism; D013482:Superoxide Dismutase / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D014466:Ultraviolet Rays / Q000009:adverse effects; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
D000975:Antioxidants; D019941:Cyclin-Dependent Kinase Inhibitor p16; D016271:Proto-Oncogene Proteins c-myc; D016160:Retinoblastoma Protein; D016159:Tumor Suppressor Protein p53; D013481:Superoxides; D014013:1,2-Dihydroxybenzene-3,5-Disulfonic Acid Disodium Salt; D007334:Insulin-Like Growth Factor I; D013482:Superoxide Dismutase; D048051:p38 Mitogen-Activated Protein Kinases; D005978:Glutathione