An anti-cell migration compound that binds to hnRNP U and suppresses nuclear deformation

Metastasis is the major cause of death in patients with solid cancers. However, the detailed mechanisms of metastasis remain unclear, with no specific drugs against metastasis approved to date. In this study, we aimed to identify the target protein of the previously reported low-molecular-weight compound, HPH-15, which inhibits lung cancer cell migration. We synthesized biotinylated HPH-15 (Biotin-HPH-15) and successfully identified heterogeneous nuclear ribonucleoprotein U (hnRNP U) as an HPH-15-binding protein using the avidin-biotin technique. hnRNP U knockdown experiments revealed that HPH-15 inhibited cell migration by binding to hnRNP U. Although HPH-15 also inhibited epithelial to mesenchymal transition (EMT), no association was observed between its anti-EMT activity and hnRNP U-binding. Moreover, hnRNP U inhibited cell migration induced by the transforming growth factor-β (TGF-β). We also examined nuclear deformation, which is known to enhance cell migration. Microscopic observation and analysis of nuclear circularity revealed that hnRNP U suppressed the transforming growth factor-β-induced decrease in nuclear circularity. HPH-15 bound to hnRNP U and enhanced its functions to increase nuclear circularity. Additionally, HPH-15 derivatization study was performed using six derivatives. Similar to HPH-15, two derivatives bound to hnRNP U, suppressed nuclear deformation, and inhibited cell migration. However, unlike HPH-15, these derivatives did not show anti-EMT activity, indicating that the anti-cell migration and anti-EMT activities of HPH-15 and its derivatives are independent functions. In conclusion, this study demonstrated the relationship between hnRNP U and nuclear deformation/cell migration and showed the roles of cell migration inhibitor HPH-15 in binding to hnRNP U and nuclear deformation. Our findings can contribute to further cancer biology studies and aid in the development of new drugs.