Artesunate Represses the Growth and Metastasis of Pancreatic Cancer Cells but Upregulates the Expression Levels of Proangiogenic Genes Through Inhibition of Protein Phosphatase 2A

Background: Artesunate (ART) has been found to exhibit remarkable anti-tumor activity. This study is aimed at investigating the significance and mechanisms of ART against pancreatic cancer cells in vitro and in vivo. Methods: MTT and pancreatic xenografts model were used to evaluate cell proliferation of pancreatic cancers. Transwell invasion and wound healing assay were used for cell invasion and migration. RNA sequencing was used to determine gene expression. PP2A activity assay was performed to confirm the inhibition of PP2A activity by ART. Molecular docking analysis was performed to predict the structure of the enzyme bond to the compound. Findings: ART markedly inhibited cell proliferation and the growth of pancreatic xenografts. ART arrested the cell cycle at G2/M phase, induced autophagy, and triggered extrinsic and intrinsic apoptotic pathways. Furthermore, ART significantly attenuated migration, invasion, and epithelial-mesenchymal transition of pancreatic cancer cells. ART exerted pro-angiogenesis potential in vivo. RNA sequencing analyses revealed that ART upregulates several pro-vascularization genes, and the downregulates a protein phosphatase 2A (PP2A) catalytic subunit (PP2Ac), which inhibition can lead to activating multiple pro-angiogenic kinase pathways. Overexpression of PP2A Y307F (constitutive active form) attenuated the upregulation of pro-vascularization genes upon ART treatment. A PP2A activity assay further confirmed a direct inhibition of PP2A activity by ART.   Interpretation: Our study indicated that PP2A is a direct target of ART, thereby suggesting that ART can be a newly identified PP2A inhibitor.   Funding Statement: This work was supported by the National Natural Science Foundation of China (grant numbers 81873587, 81472296, 81602091, 81874454, 81501970), the National Natural Science Foundation of Jiangsu Province (grant number BK20141162), the Six Major Talent Peak Project of Jiangsu Province (grant number 2015-WSN-022), the Project of Invigorating Health Care through Science, Technology and Education, Jiangsu Provincial Medical Youth Talent (grant number QNRC2016709), the Project of Jiangsu Provincial Commission of Health and Family Planning (grant number H201518), the Special Projects for Diagnosis and Treatment of Clinical Special Diseases in Suzhou (grant number LCZX201713), and the Science and Education for Health Foundation of Suzhou for Youth (grant number kjxw2015003). Declaration of Interests: The authors claim no conflicts of interest regarding the study or the manuscript. Ethics Approval Statement: Mice were purchased from Shanghai SLAC Laboratory Animal Co. Ltd. (Shanghai, China) and received humane care according to the guidelines of Soochow University Institutional Animal Care and Treatment Committee.