Vitamin K3, also known as menadione, is a synthetic lipid-soluble 2-methyl-1,4- naphthoquinone analogs of vitamin K. The vitamin K derivatives exhibit potent cytotoxicity against several cancer cell lines through ROS induction and mitochondrial dysfunction. We investigated vitamin K3-inspired derivatives as potential apoptotic inducers and analyzed their mechanisms beyond apoptosis. The cytotoxicity of a panel of vitamin K3 analogs was screened against 10 doxorubicin-sensitive and -resistant cancer cell lines overexpressing ATP-binding cassette transporters (P-glycoprotein, ABCB5, BCRP) or oncogenes (ΔEGFR) or with knockout of tumor suppressors (p53), Cell cycle arrest, apoptosis, cell migration, and microtubule formation were further investigated. The online tool SwissTargetPrediction was utilized for target prediction. Among the screened compounds, one vitamin K3 thio-derivative (No. 45, VKT-1) exhibited the most potent cytotoxicity specifically against both drug-sensitive and -resistant cancer cell lines. In addition, VKT-1 arrested the cells at the G2/M phase and induced apoptosis as detected by flow cytometry. As predicted by SwissTargetPrediction, VKT-1 targeted microtubule-associated tau protein. Indeed, VKT-1 dramatically inhibited cell migration and microtubule formation in vitro. In conclusion, the synthetic vitamin K3 thio-derivative (VKT-1) inhibited doxorubicin-sensitive and -resistant tumor cells by cell arrest, apoptosis induction, as well as, migration inhibition, and microtubule deterioration of U2OS-GFP-α-tubulin cells.
Keywords: Apoptosis; Cell cycle; Cell migration; Cytotoxicity; Leukemia; Microtubules; Vitamin K3 derivatives.