Mechanism Study of Guiqi Baizhu Formula Regulating the let-7a-5p/MDM2/p53 Axis to Promote Apoptosis and Cell Cycle Arrest in Gastric Cancer Cells

OBJECTIVE To investigate the mechanism by which Guiqi Baizhu formula regulates the let-7a-5p/MDM2/p53 axis to promote apoptosis and cell cycle arrest in gastric cancer cells.

METHODS Network pharmacology was used to predict the active components and target molecules of Guiqi Baizhu formula in the treatment of gastric cancer; the human gastric cancer HGC-27 cells with the lowest let-7a-5p expression levels were selected, and Guiqi Baizhu formula freeze-dried powder was administered at different concentration gradients at 24, 48, and 72 h; the CCK-8 assay was used to assess the effect of Guiqi Baizhu formula on the proliferation capacity of HGC-27 cells; flow cytometry was used to assess the effects of the formula on the cell cycle and apoptosis rate of HGC-27 cells; a scratch assay was conducted to evaluate the effects of the formula on the migration capacity of HGC-27 cells; real-time fluorescent quantitative polymerase chain reaction(qRT-PCR) and Western blotting were used to assess the effects of the formula on the expression levels of MDM2, p53, Cyclin D1, c-Myc, Bcl-2, and Bax proteins and their mRNA in HGC-27 cells, as well as on the expression level of let-7a-5p miRNA.

RESULTS Network pharmacology results showed that Guiqi Baizhu formula contained 160 active components, corresponding to 872 target proteins, 1656 gastric cancer-related genes, and 245 common drug-disease targets; there were 37 intersecting targets between the drug-disease common targets and the downstream target genes of let-7a-5p. CCK-8 assay results showed that Guiqi Baizhu formula exhibited concentration-dependent inhibitory effects on HGC-27 cells at various time points; flow cytometry results indicated that Guiqi Baizhu formula promoted cell cycle arrest and apoptosis in HGC-27 cells; scratch assay results demonstrated that Guiqi Baizhu formula inhibited the migratory capacity of HGC-27 cells; qRT-PCR and Western blotting results showed that Guiqi Baizhu formula reduced the protein and gene expression levels of MDM2, Cyclin D1, c-Myc, and Bcl-2, while upregulated the expression of let-7a-5p miRNA as well as the protein and gene expression levels of p53 and Bax.

CONCLUSION Guiqi Baizhu formula promotes apoptosis and cell cycle arrest in gastric cancer cells by regulating the let-7a-5p/MDM2/p53 axis.