The Effect And Mechanism Of Triptolide On Human Liver Cancer Cell Line HepG2

BackgroundTriptolide is a diterpenoid isolated from a traditional Chinese medicinal plant Tripterygium wilfordii Hook F, which has been widely used as traditional Chinese medicine to treat inflammatory and autoimmune diseases such as rheumatoid arthritis,systemic lupus and psoriatic arthritis.TPL is also the primary element of Tripterygium wilfordii Hook F,which has potent activity in not only anti-inflammation and immune modulation, but also antiproliferative and proapoptotic activity in many different types of cancer cells. The mechanism of TPL may be related to caspase pathway. Hepatocellular carcinoma is the fifth most common malignance worldwide and the second leading cause of cancer-related death in China. Only a few reports about the effect and mechanism of TPL on hepatocellular carcinoma were published.The mechanisms underlying triptolide-induced apoptosis in hepatocellular carcinoma are not clarified.PurposesTo investigate the effect of the proliferation and apoptosis, and the expression of actived caspase-3.8.9 and PARP of Hep G2 cells treated by TPL, and explore the effect and mechanism of TPL on Hep G2 cells.MethodsTPL was added into HepG2 cells with the working concentration of 10,20,40,80nmol/L as the TPL treated groups, and the culture medium was added as the control groups. HepG2 cells were harvested which had cultured for 24,48 and 72 houres and the inhibitory rates in the HepG2 cells were assessed by MTT assay. In the HepG2 cells which had cultured for 24 hours, the morphological characters were observed by hoechst staining, the apoptosis rates were determined by AnnexinV/PI flow cytometry, and the expression of actived caspase-3.8.9 and PARP proteins was examined by western blot.ResultsThe inhibitory rates of HepG2 had cultured for 24 hours with 10.20.40.80nmol/L concentration respectively were 15.2,22.5,34.9,40.7%, for 48 hours were 21.5,34.8,44.1,44.8%, for 72 hours were 31.6,47.2,51.6,56.0%. The inhibitory rates were in a dose-and time-dependent.IC50 of TPL on HepG2 was 38nmol/L. In the HepG2 cells treated by TPL had cultured for 24 hours, typical apoptotic cells were observed via hoechst staining. The apoptosis rates of the HepG2 cells treated by TPL with 10,20,40,80nmol/L concentration were 8.89%,9.81%,14.69%,22.04%respectively via FITC-Annexin V/PI flow cytometry. The expression of actived caspase-3,9 and PARP proteins in the cells that treated with TPL were higher compared to the control groups, and the expression increased with the concentration of TPL.ConclusionsOur results suggest that TPL could inhibit the proliferation and induce the apoptosis of HepG2. The apoptosis mechanism of TPL on HepG2 cells was related with the expression of actived caspase-3.9 and PARP proteins and the mitochondrial pathway, not related with caspase-8 and the death receptor pathway.