In Silico Identification and In Vitro and In Vivo Validation of Anti-Psychotic Drug Fluspirilene as a Potential CDK2 Inhibitor and a Candidate Anti-Cancer Drug.

Xi-Nan Shi,Hsiang-Fu Kung,Marie Chia-Mi Lin,Di Lu,Hongjian Li,Kwong-Sak Leung,Man-Hon Wong,Xu Liu,Hong Yao,Ling Li,Yu-Jia Chang

doi:10.1371/journal.pone.0132072

Abstract

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.

Highlights

Hepatocellular carcinoma (HCC) is the most common type of liver cancer
We evaluated the effect of fluspirilene on the growth of hepatocellular carcinoma in vivo in BALB/C nude mice subcutaneously injected with Huh7 cells (Fig 8)
The antitumor activity of oral fluspirilene (15 mg/kg) was comparable to that of 5-fluorouracil (10 mg/ kg). Their combined therapy exhibited the highest therapeutic effect. These results suggested for the first time that fluspirilene is a potential Cyclin-dependent kinase 2 (CDK2) inhibitor and a candidate anticancer drug for the treatment of human hepatocellular carcinoma

Summary

Introduction

30% to 40% of the HCC patients are eligible for curative treatments, which include surgical resection as the first option, liver transplantation and percutaneous ablation. There is a high frequency of tumor recurrence after surgical resection, and most HCCs seem resistant to conventional chemotherapy and radiotherapy. The cyclin-dependent kinase (CDK) pathways as important therapeutic targets for cancer treatment have been well established. CDKs are enzymes implicated in cell replication, and their role in tumor growth has long made them into attractive drug targets. Early industrial attempts at inhibiting CDKs to restore cell growth to normal have encountered toxicity issues. First-generation CDK inhibitors were nonspecific, inhibiting many different CDKs (there are more than 20, many of which have been implicated in various tumor types), and resulting in the type of toxicities and muted efficacy seen with older chemotherapies

Methods

Results

Discussion

Conclusion