Hepatocellular carcinoma (HCC) is one of the leading causes of
cancer-related deaths worldwide. Surgical resection and conventional
chemotherapy and
radiotherapy ultimately fail due to
tumor recurrence and HCC's resistance. The development of novel
therapies against HCC is thus urgently required. The
cyclin-dependent kinase (CDK) pathways are important and well-established targets for
cancer treatment. In particular, CDK2 is a key factor regulating the cell cycle G1 to S transition and a hallmark for
cancers. In this study, we utilized our free and open-source
protein-
ligand docking software, idock, prospectively to identify potential CDK2 inhibitors from 4,311 FDA-approved small molecule drugs using a repurposing strategy and an ensemble docking methodology. Sorted by average idock score, nine compounds were purchased and tested in vitro. Among them, the anti-psychotic
drug fluspirilene exhibited the highest anti-proliferative effect in human
hepatocellular carcinoma HepG2 and Huh7 cells. We demonstrated for the first time that
fluspirilene treatment significantly increased the percentage of cells in G1 phase, and decreased the expressions of CDK2,
cyclin E and Rb, as well as the phosphorylations of CDK2 on Thr160 and Rb on Ser795. We also examined the anti-
cancer effect of
fluspirilene in vivo in BALB/C nude mice subcutaneously xenografted with human
hepatocellular carcinoma Huh7 cells. Our results showed that oral
fluspirilene treatment significantly inhibited
tumor growth.
Fluspirilene (15 mg/kg) exhibited strong anti-
tumor activity, comparable to that of the leading
cancer drug 5-fluorouracil (10 mg/kg). Moreover, the cocktail treatment with
fluspirilene and
5-fluorouracil exhibited the highest
therapeutic effect. These results suggested for the first time that
fluspirilene is a potential CDK2 inhibitor and a candidate anti-
cancer drug for the treatment of human
hepatocellular carcinoma. In view of the fact that
fluspirilene has a long history of safe human use, our discovery of
fluspirilene as a potential anti-HCC
drug may present an immediately applicable clinical
therapy.