In silico and in vitro determination of potential RSK inhibitors for colon cancer therapy

Abstract

The Ribosomal S6 kinase (RSK) family comprises four isoforms (RSK1/2/3/4), functioning as serine/threonine kinases. RSK plays a crucial role in various physiological processes like cell growth, proliferation, and migration. RSKs play an important role due to their two catalytic regions, thus, they are proposed as cancer drug targets. To date, several small molecule inhibitors (SL0101 and BID1870) have been reported to be used in the treatment of breast and colon cancers. However, more research should be designed for novel specific inhibitors of RSKs. The aim of this study is to perform the determine of potential RSK inhibitors with in silico virtual screening and molecular modeling studies and then, evaluate cytotoxic effect and inhibitor potential of the selected compound in in vitro studies on colon cancer cell lines. For this purpose, we screened the databases and performed molecular docking study via Glide/SP method of Maestro (Schrödinger). For cytotoxicity assay, the cells were treated with five different doses of inhibitor (150, 75, 39, 18 and 9µM). The cell viability values were obtained at 550 nm spectrophotometrically. Also, the inhibitory activity of potential inhibitor was searched with western blotting method using p­RSK antibody. As a result, the potential inhibitor demonstrated a pronounced cytotoxic effect on HT29 cells. Additionally, it led to approximately a 2­fold downregulation of the RSK protein compared to the control group (non­treated cells). The expression of apoptosis­related proteins was assessed through western blotting, revealing an upregulation of Bax and a downregulation of Bcl­2 in the presence of the potential inhibitor compared to the control group. According to our findings, substituted­benzofuro compound have a promising candidate as RSK inhibitor against colon cancer cell lines.