Network pharmacology identification and in Vivo validation of key pharmacological pathways of Phyllanthus reticulatus (Euphorbiaceae) leaf extract in liver cancer treatment

Phyllanthus reticulatus (Euphorbiaceae) is a medicinal plant that has been used in Zhuang medicine since ancient times. Traditionally, it has the effect of removing toxins and detumescence and can be used to treat hepatitis in China and India. Our previous studies have proved that the ethyl acetate extract of its leaves (PRPE) has an anti-hepatoma effect.To predict targets of an ethyl acetate extract of Phyllanthus reticulatus leaves (PRPE) in hepatoma treatment via network pharmacology and verify the predictions in a mouse model of liver cancer.Chemical constituents and therapeutic targets of P. reticulatus (PRP) were searched and predicted via public databases. A protein-protein interaction network comprising common targets was constructed, and the key gene targets were identified. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were used for biological function and pathway enrichment analyses. The effects of PRP on BEL-7404 and HepG2 cells were determined by MTT assay, apoptosis was measured by flow cytometry and hoechst44432/PI. And a nude mouse xenograft model was established to verify the anti-tumour effect in vivo. The histopathology of tumours was observed by staining with haematoxylin and eosin (H&E). Reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemistry were used to determine the gene and protein expression levels of phosphoinositide 3-kinase (PI3K), Akt1, p53, caspase-3, Bcl-2 and Bax, respectively.Twenty-seven chemical components and 567 potential therapeutic targets of PRP were identified. GO analysis indicated that these targets are mainly associated with peptidyl-tyrosine phosphorylation and steroid metabolic process. KEGG analysis showed that the targets are mainly located in the PI3K/Akt, apoptosis, mitogen-activated protein kinase (MAPK), Ras and vascular endothelial growth factor (VEGF) signalling pathways. According to the p-adjust value, the PI3K/Akt pathway is the core pathway. In vitro, PRPE could inhibit proliferation and induce apoptosis in hepatoma cells. IC50 values of PRPE were 2.48 and 6.34 mg/mL for BEL-7404 and hepG2 cells, respectively. PRPE significantly reduced tumour volume and weight. H&E results showed that PRPE repaired necrotic areas in hepatoma cells. PRPE reduced the protein expression of PI3K, Akt1 and Bcl-2 and increased the protein expression of p53 and Bax. Meanwhile, PRPE reduced the mRNA expression of PI3K, AKT1 and BCL2 and increased the mRNA expression of TP53, CASP3 and BAX.The targets of PRPE are the PI3K/Akt, apoptosis, MAPK, Ras and VEGF signalling pathways. Passing through the PI3K/Akt pathway to induce apoptosis is the main mechanism of PRPE.