SirtinolS2804

Sirtinol potently inhibits recombinant yeast Sir2p activity in vitro with IC50 of 68 μM. Unlike TSA, Sirtinol has shown no effect on human HDAC1, indicating that it is a selective sirtuin inhibitor. Unlike TSA, treatment of human primary fibroblasts with Sirtinol does not cause global changes in acetylation of histones and tubulin, nor does it induce a morphological change in the HeLa tumor cell line. ^[1] Sirtinol treatment at 100 μM for 24 hours causes a sustained growth arrest in MCF-7 and H1299 cells for up to 9 days after Sirtinol withdrawal. Sirtinol treatment induces increased SA-β-gal activity and expression of PAI-1 in both MCF-7 and H1299 cells, more potently than Splitomicin. Sirtinol inhibits colony formation at concentrations of 33 μM and higher in MCF-7 and H1299 cells, more effectively compared with Splitomicin. Sirtinol treatment (100 μM) significantly attenuates both basal and EGF- or IGF-I-stimulated phosphorylation of ERK, JNK/SAPK and p38 MAPK in MCF-7 and H1299 cells. Sirtinol blocks the basal and EGF-stimulated activation of Ras. Consistent, basal and EGF- or IGF-I-stimulated phosphorylation of Raf-1, MEK, SEK1/MKK4 and MKK7 is attenuated in Sirtinol-treated cells. ^[3] Inhibition of Sirt1 by Sirtinol enhances UV- and H₂O₂-induced p53 acetylation to enhance cell death in cultured skin keratinocytes. ^[6] Blocking of Sirt1 by Sirtinol treatment results in a significant inhibition in the growth and viability of human PCa cells while having no effect on normal prostate epithelial cells. ^[7]