Abstract: Objective To investigate the effects of pristimerin on the proliferation and apoptosis of human bladder cancer HT⁃1376 cells and the related mechanisms. Methods The target protein of pristimerin was predicted by TCMSP, SwissTargetPrediction database and PharmMapper database, and the target of bladder cancer was obtained from GeneCards database. The potential targets of pristimerin in the treatment of bladder cancer were integrated through the Venny 2.1.0 platform; the String database and Cytoscape 3.9.1 software were used to construct a protein⁃protein interaction (PPI) network. GO function and KEGG pathway enrichment analyses were performed by DAVID database. The normal human bladder epithelial cells SV⁃HUC⁃1 and human bladder cancer cell line HT⁃1376 cells were cultured in vitro, and treated with 0-0.8 μmol/L pristimerin. The effects of pristimerin on the proliferation and apoptosis of HT⁃1376 cells were detected by CCK⁃8 assay, colony formation assay, Hoechst⁃PI staining assay. Western blot was used to detect the expression levels of apoptosis⁃related proteins Bcl⁃2, Bax, Cleaved PARP, PARP, and MEK/ERK signaling pathway⁃related proteins p⁃MEK, p⁃ERK1/2. Results  There were 292 targets of pristimerin, among which 114 potential targets were related to bladder cancer treatment, involving 434 biological processes, 54 cellular components and 114 molecular functions, mainly enriched in 132 signaling pathways such as MAPK signaling pathway, lipid and atherosclerosis, etc. The results of in vitro experimental verification showed that pristimerin could significantly inhibit the viability and colony formation ability of HT⁃1376 cells and induce cell apoptosis(all P<0.05). Western blot showed that compared with untreated control group, the expression levels of apoptosis⁃related proteins Bax and Cleaved PARP were increased, Bcl⁃2 and PARP were decreased, and MEK/ERK signaling pathway⁃related proteins p⁃MEK and p⁃ERK1/2 were decreased after treated with 0.65 μmol/L pristimerin (all P<0.05). Conclusions Pristimerin may inhibit the proliferation and induce apoptosis of bladder cancer cells by regulating the phosphorylation level of MEK/ERK signaling pathway⁃related proteins.

Key words: Bladder Cancer, Pristimerin, Network pharmacology, Proliferation, Apoptosis, MEK/ERK