Int J Biol Sci 2019; 15(7):1523-1532. doi:10.7150/ijbs.32625 This issue
1. Department of the second medical oncology, The 3rd Affiliated Hospital of Kunming Medical University, Yunnan Tumor Hospital, Kunming, China.
2. Department of Urology, the 1st Affiliated Hospital of Kunming Medical University, Kunming, China
3. SDIVF R&D Centre, Hong Kong Science Park, Sha Tin, New Territories, Hong Kong.
4. CUHK-SDU Joint Laboratory on Reproductive Genetics, School of Biomedical Sciences, The Chinese University of Hong Kong, Sha Tin, New Territories, Hong Kong.
5. Department of the radiation oncology, The 3rd Affiliated Hospital of Kunming Medical University, Yunnan Tumor Hospital, Kunming, China.
6. Department of the colorectal surgery, The 3rd Affiliated Hospital of Kunming Medical University, Yunnan Tumor Hospital, Kunming, China.
7. Department of Pathophysiology, School of Basic Medical Sciences, Yunnan University of TCM, Kunming, China.
8. Biomedical Engineering Research Center, Kunming Medical University, Kunming, Yunnan, China
9. Department of Otolaryngology, Head and Neck Surgery, Kunming Children's Hospital, Kunming, China.
10. Key Laboratory of Animal Models and Human Disease Mechanisms of Chinese Academy of Sciences and Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan, China
11. Institute of Medical and Pharmaceutical Sciences, The Academy of Medical Science, Zhengzhou University, Zhengzhou, China.
# These authors contributed equally to this work.
Background: The phosphatidylinositol 3-kinase (PI3K)/AKT signaling pathway is hyperactivated in lung cancer and regulates a broad range of cellular processes, including proliferation, survival, angiogenesis, and metastasis. Thus PI3K is considered a promising target for therapy. To date, PI3K inhibitors have not been approved for lung cancer. Recent studies showed that the antipsychotic agent flupentixol induced apoptosis of lung cancer cell, however the anti-tumor mechanism of flupentixol remains unclear.
Methods: (1) The idock software simulated the molecular docking between the PI3Kα protein and flupentixol. (2) Inhibition of PI3Kα by the flupentixol was examined by in vitro kinase assays. (3) The cytotoxicity of flupentixol on the NSCLC cell lines was tested by MTT assays. (4) We treated A549 and H661 cells with flupentixol and then measured the percentage of apoptotic cells by the Annexin V/PI analysis. (5) We investigated the effect of flupentixol on the expression of critical PI3K/AKT signaling pathway proteins, further analyzed on the cleavage of PARP and caspase-3 by Western blotting. (6) BALB/C nude mice were subcutaneously injected with A549 cells to evaluate the effect of flupentixol on the growth of lung carcinoma.
Results: Structural analysis of the predicted binding conformation suggested that flupentixol docks to the ATP binding pocket of PI3Kα. Kinase assays demonstrate that flupentixol indeed inhibited the PI3Kα kinase activity. Flupentixol exhibited cytotoxicity in lung cancer cell lines A549 and H661 in a dose- and time-dependent manner. Furthermore, flupentixol more strongly inhibited the phosphorylation of AKT (T308 and S473) and the expression of its downstream target gene Bcl-2 than two known PI3K inhibitors (BYL719 and BKM120). Flupentixol induced apoptosis as measured by PARP and caspase-3 cleavage. Finally, flupentixol significantly suppressed A549 xenograft growth in BALB/C nude mice.
Conclusions: Flupentixol could be docked to the PI3Kα protein and specifically inhibit the PI3K/AKT pathway and survival of lung cancer cells in vitro and in vivo. As an old drug, flupentixol is a new PI3K inhibitor that may be used for the treatment of lung cancers.
Keywords: Flupentixol, PI3K inhibitor, PI3Kα, Lung cancer