In silico and in vitro Studies of the (+)-2,3,9-Trimethoxypterocarpan and Vorinostat Association as an Epigenetic Strategy to Inhibit Human Cancer Cells

Abstract

Recent years have highlighted the potential of flavonoids to enhance the efficacy and/or sensitivity of chemotherapeutics. The combination of histone deacetylase (HDAC) inhibitors with natural compounds has shown positive results. Thus, this study evaluates the association of pterocarpan and vorinostat, a potential epigenetic strategy against cancer cells, using in silico and in vitro approaches. The methodology involved using computational tools to map molecular targets and construct protein-protein interaction networks, followed by in vitro assays to evaluate cytotoxicity in cancer cell lines. The antiproliferative effects of the combination ((+)-2,3,9-trimethoxypterocarpan ((+)-PTC) + vorinostat) were assessed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays. The combination index (CI) was calculated to determine synergistic effects between the compounds. Molecular target prediction followed by evaluation of up-or downregulated expression in PC-3 (prostate carcinoma), DU-145 (prostate carcinoma), KG-1 (acute myeloid leukemia), and MOLM-13 (acute myeloid leukemia) cell lines identified 36 targets, including interleukin 1 beta (IL1B), tumor necrosis factor (TNF), amyloid beta precursor protein (APP), MYC proto-oncogene, bHLH transcription factor (MYC) and Heat Shock Protein 90 (HSP90). Additionally, all vorinostat targets (HDACs 1-10) were evaluated. Docking experiments indicated stable complexes between (+)-PTC and HDAC1 (PDB: 4BKX), HDAC2 (PDB: 4LXZ), HDAC6 (PDB: 5B8D), and HDAC8 (PDB: 1T64). Minimum inhibitory concentrations varied among cell lines, with in vitro associations showing inhibitory concentrations ranging from 1.5 to 2.9 µM. The combination of (+)-PTC and vorinostat shows greater inhibition of cell proliferation than either compound alone.

Keywords:
vorinostat; (+)-2,3,9-trimethoxypterocarpan; IC₅₀; combination index; inhibition of cell growth