A study on the anti-tumor mechanism of total flavonoids from Radix Tetrastigmae against additional cell line based on COX-2-mediated Wnt/β-catenin signaling pathway

Abstract

This study is to explore the effect of total flavonoids from Radix Tetrastigmae (TF) against hepatic cancer and discuss the acting mechanism. Proliferation of HepG2 cells was promoted by PGE2 and Butaprost. Using AH6809 as the positive control, the inhibitory effect of TF on additional cell line was detected through a CCK-8 assay, the apoptosis rate was detected by flow cytometry, and the nuclear morphology of cells were observed by Hochest33258 staining. Then PCR was applied to determine the mRNA expression. The corresponding Protein expression were determined by Western Blot. The effects of TF on the body weight, tumor growth volume and tumor inhibition rate were observed in nude mice model of human hepatocellular carcinoma by vivo experiments. The results showed TF had an obvious inhibitory effect on HepG2 cells with a significant dose-dependent manner (P<0.01). Pyknosis was found under the fluorescence microscope after TF treatment for 24h by Hochest33258 staining. Typical features of apoptosis were observed in HepG2 cells treated with TF and the apoptosis rate increased with increase of concentration of the TF. mRNA expression levels of GSK-3β, Akt, VEGF, COX-2 and β-catenin were down regulated greatly by the TF in HepG2 cells. Moderate and high concentrations of TF led to an obvious down regulation of GSK-3β, p-GSK-3β, Akt, p-Akt, VEGF, COX-2 and β-catenin in HepG2 cells, while p-β-catenin was up regulated. The tumor inhibition rates with high, medium and low dose of TF were 64.07%, 53.64%, 46.69%, respectively. The inhibitory effect of total flavonoids on tumor growth in mice was better than that of CTX, and the inhibitory effect of TF on tumor growth was less than CTX. TF exhibited a significant inhibitory effect on HepG2 cells, promoting the apoptosis of HepG2 cells in a dose-dependent manner. TF was also regulatory of the COX-2-Wnt/β-catenin signaling pathway, which was presumed to be the working mechanism of Tetrastigmae.