Abstract: Objective To investigate the effect of Paeoniflorin in inhibiting the progression of endometrial cancer and its mechanism. Methods  The target gene of Paeoniflorin was predicted by TargetNet and Swiss target prediction online databases, the expression of Paeoniflorin target gene in endometrial cancer was analyzed by UALCAN database, and the expression of Paeoniflorin target gene in patients with different clinicopathological characteristics was analyzed by TCGA database. The endometrial cancer cell lines HEC108 and Ishikawa were cultured in vitro, and were divided into the Control group/Vector group (no treatment), the AURKA group (transfected with AURKA plasmid), the Paeoniflorin group and the Paeoniflorin+AURKA group (treated with Paeoniflorin and transfected with AURKA plasmid). The target gene of Paeoniflorin was predicted by bioinformatics. The cells were treated with Paeoniflorin at different concentrations. The cells activity was detected by CCK⁃8 assay. The cells migration and invasion were detected by Transwell assay. The activity of lactate dehydrogenase (LDH) was detected by the enzyme⁃linked immunosorbent assay. The cells proliferation inhibited by Paeoniflorin in vivo was detected by the transplanted tumor assay in nude mice. The proliferating cell antigen (Ki⁃67) was detected by immunohistochemistry. The expression of AURKA, migration⁃related proteins and epithelial mesenchymal transition (EMT)⁃related proteins were detected by Western Blot. Results Bioinformatics showed that AURKA was the target of Paeoniflorin, which was highly expressed in endometrial cancer tissues and related to clinical adverse phenotypes (P<0.05). The vitro experiment results showed that Paeoniflorin could inhibit cells proliferation, migration and invasion of HEC108 and Ishikawa cells, increase LDH activity, inhibit Ki⁃67 expression (all P<0.05), the levels of migration⁃related proteins (MMP2, MMP9) in cells, and regulate the levels of EMT⁃related proteins (Vimentin, N⁃cadherin, Snail, E⁃cadherin) in cells (all P<0.05).  Paeoniflorin could inhibit the growth of volume and the weight of transplanted tumors in nude mice (all P<0.05), as well as the expression of AURKA protein in concentration⁃ and time⁃dependent manners (all P<0.05). The high expression of AURKA could promote cells proliferation and reduce LDH activity (all P<0.05). Conclusions Paeoniflorin inhibited the expression of Proliferation, migration and invasion of endometrial cancer cells in vitro and the growth of transplanted tumor in nude mice in vivo. The mechanism may be that Paeoniflorin inhibits the development of endometrial cancer by down⁃regulating AURKA expression.

Key words: Endometrial cancer, Paeoniflorin, Proliferation, Migration, Invasion