Shikonin Mediates Apoptosis through G Protein-Coupled Estrogen Receptor of Ovarian Cancer Cells

This study was intended to establish the predictive target of Shikonin (SK) against ovarian cancer using network pharmacology and to clarify the potential mechanism of SK in promoting apoptosis in ovarian cancer. Cell Counting Kit-8 assay, plate clone assays, LDH assay, flow cytometric analysis of Annexin V-fluorescein isothiocyanate/propidium iodide staining, and western blotting were used to assess the effect of SK on apoptosis of ovarian cancer cell lines (SKOV3 and A2780). Pharmacodynamic targets were used to predict the targets of SK and ovarian cancer. Gene Ontology (GO) enrichment analysis and Kyoto Encyclopedia of Gene and Genome (KEGG) pathway enrichment analyses were used to analyze the biological functions and signal pathways of these targets. SK promoted apoptosis in ovarian epithelioid adenocarcinoma cells. SK-ovarian cancer pharmacodynamic target analysis screened 17 related genes. GO and KEGG analyses showed that SK affected the estrogen signaling pathway. SK inhibited the expression of GPER in SKOV3 and A2780 cells and downregulated the expression of EGFR, p-EGFR, PI3K, and p-AKT in a concentration-dependent manner. The apoptosis-promoting effect of SK was enhanced by GPER-specific agonist G1 and inhibited by the specific inhibitor G15. The expression of EGFR, p-EGFR, PI3K, and p-AKT was decreased by G1 and reversed by G15. SK also inhibited tumor growth in the SKOV3 xenograft model, and it acted synergistically with G1. However, the effect can be attenuated by G15 in vivo. In summary, SK may affect the apoptosis of ovarian cancer cells through GPER/EGFR/PI3K/AKT, and GPER may be a key target of SK in ovarian cancer cell apoptosis.