Identification of novel SIRT1 up-regulators using a cell-based high-throughput screening assay

Sirtuin 1 (SIRT1) has emerged as a promising therapeutic target for many diseases such as neurodegenerative disorders. Resveratrol, a plant polyphenol, is known to induce SIRT1 expression and activity. To excavate active compounds that can increase SIRT1 transcription from FDA-approved drugs, a cell-based SIRT1 up-regulator screening assay was developed. 293A cells were transfected with a SIRT1-promoter-luciferase reporter gene construct, and the stably transfected cell line was selected to establish a specific SIRT1 expression assay in 96-well microplate format using resveratrol as a positive control. The evaluating parameter Z' value of 0.67 supported the stability and reliability of this cell-based high-throughput screening (HTS) assay. Screening of 1523 drugs identified 17 compounds up-regulating SIRT1 transcriptional activity by over 200 %. The 17 compounds could elevate SIRT1 transcription in a dose-dependent character, and their EC₅₀ values were lower than that of resveratrol. The top three active compounds including belinostat, panobinostat and vorinostat belonging to pan-histone deacetylase inhibitor (HDACi) were furtherly observed to enhance the SIRT1 mRNA level and the H3 acetylated protein level in 293A cells, and interact with SIRT1 revealed by molecular docking. Moreover, belinostat, a potential candidate for the treatment of the severe neurodegenerative disease multiple sclerosis (MS), could also up-regulate the SIRT1 mRNA and protein levels in the spinal cords of experimental autoimmune encephalomyelitis (EAE) mice. These findings suggest that SIRT1 up-regulators originated from this HTS assay might become new drug candidates for the treatment of neurodegenerative disease, which provides an approach to repositioning approved drugs through HTS assay.