BackgroundColorectal cancer has become one of the leading cause of cancer morbidity and mortality throughout world. Hederagenin, a derivative of oleanolic acid isolated from the leaves of ivy (Hedera helix L.), has been shown to have potential anti-tumor activity. The study was conducted to evaluate whether hederagenin could induce apoptosis of human colon cancer LoVo cells and explore the possible mechanism.MethodsMTT assay was used for evaluating cell viability while Annexin V-FITC/PI assay and Hoechst 33342 nuclear stainining were used for the determination of apoptosis and mitochondrial membrane potential. DCFH-DA fluorescence staining and flow cytometry were used to measure ROS generation. Real-time PCR and western blot analysis were performed for apoptosis-related protein expressions.ResultsMTT assay showed that hederagenin could significantly inhibit the viability of LoVo cells in a concentration-dependent and time-dependent manner by IC50 of 1.39 μM at 24 h and 1.17 μM at 48 h. The apoptosis ratio was significantly increased to 32.46% and 81.78% by the induction of hederagenin (1 and 2 μM) in Annexin V-FITC/PI assay. Hederagenin could also induce the nuclear changes characteristic of apoptosis by Hoechst 33342 nuclear stainining under fluorescence microscopy. DCFH-DA fluorescence staining and flow cytometry showed that hederagenin could increase significantly ROS generation in LoVo cells. Real-time PCR showed that hederagenin induced the up-regulation of Bax and down-regulation of Bcl-2, Bcl-xL and Survivin. Western blotting analysis showed that hederagenin decreased the expressions of apoptosis-associated proteins Bcl-2, procaspase-9, procaspase-3, and polyADP- ribosepolymerase (PARP) were increased, while the expressions of Bax, caspase-3, caspase-9 were increased. However, there was no significant change on caspase-8.ConclusionsThese results indicated that the disruption of mitochondrial membrane potential might contribute to the apoptosis of hederagenin in LoVo cells. Our findings suggested that hederagenin might be a promising therapeutic candidate for human colon cancer.

P. polyphylla Smith var. chinensis (Franch.) Hara (PPSCFH) has been used as medicinal Paris for the prevention and treatment of cancers in China for thousands of years. Its main components, steroidal saponins (PRS), have been confirmed to inhibit tumor OPEN ACCESSMolecules 2013, 18 12917 growth. In the present study, the immunostimulation of PRS was investigated in Lewis bearing-C57BL/6 mice while the induction of apoptosis in A549 cells was also studied. The treatment with PRS (2.5, 5.0 and 7.5 mg/kg) significantly inhibited tumor, volume, and weight in the C57BL/6 mice. The rates of inhibition of PRS (at 2.5, 5.0 and 7.5 mg/kg) were 26.49 ± 17.30%, 40.32 ± 18.91% and 54.94 ± 16.48%, respectively. The spleen and thymus indexes were increased remarkably, while the levels of inflammatory cytokines including TNF-α, IL-8 and IL-10 in serum were decreased according to ELISA assays. For A549 cells, Hoechst 33342 staining and annexin V/PI by flow cytometry showed that PRS (0.25, 0.50 and 0.75 mg/mL) induced nuclear changes of A549 cells with DNA condensation and fragmentations of chromatin, as well as inducing apoptosis. Furthermore, PRS could also attenuate the over-generation of intracellular ROS. Western blotting analysis showed a significant decrease on the expressions of proinflammatory cytokines MCP-1, IL-6 and TGF-β1, as well as cell adhesion molecule ICAM-1, by treatment with PRS. Our results demonstrated that the inhibition of PRS on tumor growth might be associated with the amelioration of inflammation responses, induction of apoptosis, as well as the decrease of ROS. These results suggested that PRS implied a potential therapeutic effect in the lung cancer treatment.

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