Structural changes and anti-hepatocellular carcinoma activity of interferon- after interaction with sinensetin

Exploring the interaction of small molecules with therapeutic proteins can provide useful information about development of ligand-protein complexes as synergistically therapeutic platforms. In this study, the interaction of sinensetin with human interferon gamma (IFN gamma) was evaluated experimentally and theoretically. Also, the synergistic effects of IFN gamma-sinensetin complex on the inhibition of hepatocellular carcinoma HepG2 cell pro-liferation were assessed by cell viability and quantitative real time PCR assays. It was realized that sinensetin interacts with IFN gamma through a static quenching mechanism and hydrophobic forces mediated by presence of Lys55 and Lys58 amino acid residues in the binding site were the main contributing forces in the spontaneous formation of IFN gamma-sinensetin complex. Also, the interaction of sinensetin with IFN gamma did not induce a significant change in the secondary and tertiary structure of the protein. Cellular assays revealed a synergistic effect of sinensetin on IFN gamma -triggered anticancer action in HepG2 cells through overexpression of caspase-3 mRNA and protein. In conclusion, this study may hold great promise for the development of potential ligand-protein complexes for therapeutic purposes.