Y-box Binding Protein 1 as a Target Molecule of a Novel Coumarin-based Anti-metastatic Agent

We previously demonstrated that a novel coumarin-based compound, 7,8-dihydroxy-3-(4'-hydroxyphenyl)coumarin (DHC), suppresses metastasis of LM8 osteosarcoma cells both in vitro and in vivo. However, the molecular target of DHC remains unclear. The aim of this study was to develop novel DHC-derived compounds and to identify their target molecule.

Novel coumarin-based compounds were designed and evaluated for their effects on LM8 osteosarcoma cell invasion and migration. To identify a candidate target molecule of the newly synthesized compound SSKP-0076, liquid chromatography-mass spectrometry analysis was performed. The identified candidate molecule was further validated using RNA interference.

Three novel coumarin-based compounds, SSKP-0076, SSKP-0081, and SSKP-0082, were synthesized. All compounds significantly inhibited invasion and migration of LM8 cells. Liquid chromatography-mass spectrometry combined with Mascot database searching identified Y-box binding protein 1 (Ybx1) as a candidate target molecule of SSKP-0076. Knockdown of Ybx1 by specific siRNAs significantly suppressed invasion and migration of LM8 cells and reduced the protein expression of the small GTP-binding proteins RhoA and Rac1, without affecting their mRNA expression levels. These effects were consistent with those observed following DHC treatment.

Ybx1 is a potential target molecule of the novel anti-metastatic coumarin-based compound SSKP-0076.