Tenovin-1 Induces Senescence and Decreases Wound-Healing Activity in Cultured Rat Primary Astrocytes

Brain aging induces neuropsychological changes, such as decreased memory capacity, language ability, and attention; and is also associated with neurodegenerative diseases. However, most of the studies on brain aging are focused on neurons, while senescence in astrocytes has received less attention. Astrocytes constitute the majority of cell types in the brain and perform various functions in the brain such as supporting brain structures, regulating blood-brain barrier permeability, transmitter uptake and regulation, and immunity modulation. Recent studies have shown that SIRT1 and SIRT2 play certain roles in cellular senescence in peripheral systems. Both SIRT1 and SIRT2 inhibitors delay tumor growth in vivo without significant general toxicity. In this study, we investigated the role of tenovin-1, an inhibitor of SIRT1 and SIRT2, on rat primary astrocytes where we observed senescence and other functional changes. Cellular senescence usually is characterized by irreversible cell cycle arrest and induces senescence-associated β-galactosidase (SA-β-gal) activity. Tenovin-1-treated astrocytes showed increased SA-β-gal-positive cell number, senescence-associated secretory phenotypes, including IL-6 and IL-1β, and cell cycle-related proteins like phospho-histone H3 and CDK2. Along with the molecular changes, tenovin-1 impaired the wound-healing activity of cultured primary astrocytes. These data suggest that tenovin-1 can induce cellular senescence in astrocytes possibly by inhibiting SIRT1 and SIRT2, which may play particular roles in brain aging and neurodegenerative conditions.

Induction of Nuclear Enlargement and Senescence by Sirtuin Inhibitors in Glioblastoma Cells

Sirtuin family members with lysine deacetylase activity are known to play an important role in anti-aging and longevity. Cellular senescence is one of the hallmarks of aging, and downregulation of sirtuin is reported to induce premature senescence. In this study, we investigated the effects of small-molecule sirtuin inhibitors on cellular senescence. Various small molecules such as tenovin-1 and EX527 were employed for direct sirtuin activity inhibition. U251, SNB-75, and U87MG glioblastoma cells treated with sirtuin inhibitors exhibited phenotypes with nuclear enlargement. Furthermore, treatment of rat primary astrocytes with tenovin-1 also increased the size of the nucleus. The activity of senescence-associated β-galactosidase, a marker of cellular senescence, was induced by tenovin-1 and EX527 treatment in U87MG glioblastoma cells. Consistent with the senescent phenotype, treatment with tenovin-1 increased p53 expression in U87MG cells. This study demonstrated the senescence-inducing effect of sirtuin inhibitors, which are potentially useful tools for senescence research.