Synthetic Isoliquiritigenin Inhibits Human Tongue Squamous Carcinoma Cells through Its Antioxidant Mechanism

Isoliquiritigenin (ISL), a natural antioxidant, has antitumor activity in different types of cancer cells. However the antitumor effect of ISL on human tongue squamous carcinoma cells (TSCC) is not clear. Here we aimed to investigate the effects of synthetic isoliquiritigenin (S-ISL) on TSCC and elucidate the underlying mechanisms. S-ISL was synthesized and elucidated from its nuclear magnetic resonance spectrum and examined using high performance liquid chromatography. The effects of S-ISL on TSCC cells (Tca8113) were evaluated in relation to cell proliferation, apoptosis and adhesion, migration, and invasion using sulforhodamine B assay, fluorescence microscopy technique, flow cytometry (FCM) analysis, and Boyden chamber assay. The associated regulatory mechanisms were examined using FCM and fluorescence microscopy for intracellular reactive oxygen species (ROS) generation, Gelatin zymography assay for matrix metalloproteinase (MMP) activities, and Western blot for apoptosis regulatory proteins (Bcl-2 and Bax). Our data indicated that S-ISL inhibited Tca8113 cell proliferation, adhesion, migration, and invasion while promoting the cell apoptosis. Such effects were accompanied by downregulation of Bcl-2 and upregulation of Bax, reduction of MMP-2 and MMP-9 activities, and decreased ROS production. We conclude that S-ISL is a promising agent targeting TSCC through multiple anticancer effects, regulated by its antioxidant mechanism.