Quinazolines as novel anti-inflammatory histone deacetylase inhibitors

Histone deacetylase (HDAC) inhibitors regulate many biological responses, including anti-inflammatory and anti-cancer effects. We sought to identify novel classes of HDAC inhibitors from in-house compound libraries. Initially, compounds from 26 different structural classes that showed anti-inflammatory effects in a pre-screen in HEK293T cells were tested in vitro for HDAC inhibition, using a commercial fluorescence assay. The known HDAC inhibitors suberoylanilide hydroxamic acid (SAHA) and trichostatin A (TSA) were used as positive controls. Examples of three different structural classes (anilinoacridines, phenylpyrrolocarbazoles and benzofurylquinazolines) showed significant inhibition in the HDAC assay, and small subsets of these were also evaluated, seeking initial structure-activity relationships (SAR) for each class. Several of the most effective compounds from this HDAC screen were evaluated for their effects on the expression of the pro-inflammatory gene, IL1-alpha, and the cancer-related genes, p53, p21, E-cadherin and C-MYC. While the benzofurylquinazolines increased the expression level of the pro-inflammatory gene IL1-alpha as well as p21 and p53 in the PC3 cell line, a phenylpyrrolocarbazole had the converse effect on p53 expression. Several of the compounds showed in vitro HDAC inhibition ability in PC3, HCT116 and NIH-3T3 cell lines comparable to that of SAHA.