• Ya-jun Lin, Yong-zhan Zhen, Jie Wei, Bo Liu, Zong-yuan Yu, and Gang Hu.
• The Key Laboratory of Geriatrics, Beijing Hospital & Beijing Institute of Geriatrics, Ministry of Health, Beijing, China.
• Acta Pharmacol. Sin. 2011 Oct 1; 32 (10): 1246-52.

AimTo observe the effect of Rhein lysinate (RHL) on cellular senescence of human umbilical vascular endothelial cells (HUVECs) and elucidate its action mechanism.MethodsCell viability was determined using MTT assay. The expression levels of Sirt1 mRNA and protein were measured by RT-PCR and Western blot, respectively. Senescence associated (SA)-β-galactosidase activity was detected to evaluate cell senescence. Apoptosis and cell cycle progression were determined using flow cytometry.ResultsTreatment with RHL (10 μmol/L) for 48 h significantly increased the proliferation of HUVECs. In contrast, treatment with H2O2 (25, 50 and 100 μmol/L) for 6 d dose-dependently increased β-galactosidase positive cells. Spontaneous cell senescence appeared as the cell passage increased. Pre-treatment with RHL (10 μmol/L) reversed H2O2 or increased cell passage-induced cell senescence. H2O2(100 μmol/L) significantly arrested HUVECs at G(1) phase (73.8% vs 64.6% in the vehicle group), which was blocked by RHL (10 μmol/L). RHL (5 and 10 μmol/L) enhanced both mRNA transcription and protein expression of Sirt1. H2O2 (100 μmol/L) significantly decreased Sirt1 expression, and induced up-regulation of p53 acetylation and p16(INK4a), which were blocked by pre-treatment with RHL (10 μmol/L). Interference with siRNA for Sirt1 abolished the effect of RHL. H2O2 (100 μmol/L) did not induce HUVEC apoptosis. The expression of apoptosis-associated proteins, such as p53, p21, Bcl-2, and Bax, did not significantly change in the presence of H(2)O(2) (100 μmol/L) or RHL (10 μmol/L).ConclusionRHL protected HUVECs against cellular senescence induced by H2O2, via up-regulation of Sirt1 expression and down-regulation of the expression of acetyl-p53 and p16(INK4a).

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