Paris Polyphylla Monomer PP-26 Induces Mitochondrial Pathway-Mediated Cell Apoptosis by Inhibiting the PI3K/Akt Pathway in Human Gastric Cancer Cells

Background: Paris polyphylla is a traditional Chinese medicinal herb that has been used as a haemostatic, antimicrobial and anticancer agent. Gastric cancer (GC) is a global health problem, with more than 1 million people newly diagnosed with gastric cancer worldwide each year.Methods: The MTT and colony formation assay were used to test the anti-proliferative effects of PP-26 on MGC-803 and BGC-823 cells. Flow cytometry assays, Hoechst 33258 staining assay and Caspase inhibitor Z-VAD-FMK were used to test apoptosis. JC-1 staining used to measure changes in mitochondrial membrane potential and western blot analysis were used to test apoptotic and PI3K/Akt pathway related proteins.Results: PP-26 had a dose-dependent inhibitory effect on the proliferation of MGC-803 and BGC-823 cells, but had no obvious anti-proliferative effect on normal liver LO2 cells and normal embryonic kidney HEK-293 cells. Additionally, PP-26 induced typical apoptotic morphological changes, such as nuclear pyknosis, nuclear cracking and apoptotic bodies. Moreover, PP-26 induced a decrease in mitochondrial membrane potential. And PP-26 modulated the expression of Bcl-xL, Mcl-1, Bax, caspase-9/-3 and PARP proteins and induced cell apoptosis through the mitochondrial apoptotic pathway. Next, using an irreversible general caspase inhibitor (Z-VAD-FMK), we confirmed the activation of the mitochondrial apoptotic pathway induced by PP-26. Furthermore, PP-26 inhibited the phosphorylation of Akt and GSK-3β. The inhibition of Akt protein activated the mitochondrial apoptotic pathway.Conclusion: Collectively, these results indicated that PP-26 inhibited the proliferation of MGC-803 and BGC-823 cells by inhibiting the Akt signalling pathway and activating the mitochondrial apoptotic pathway.

Toosendanin Shows Potent Efficacy Against Human Ovarian Cancer through Caspase-Dependent Mitochondrial Apoptotic Pathway

Toosendanin (TSN) is a triterpenoid extracted from the bark or fruits of Melia toosendan Sieb et Zucc, which is a traditional Chinese medicine and mainly grows in China and India. TSN has been verified to possess antitumor activities on various human cancers, whereas the effects of TSN on ovarian cancer (OC) has not been reported yet. Here, TSN was shown to significantly inhibit proliferation of SKOV3 and OVCAR3 cell lines in a dose- and time-dependent manner. Treatment of OC cells with TSN resulted in colony formation reduction, S and G2/M phase arrest, cell apoptosis, and dramatic decrease in mitochondrial membrane potential. Furthermore, TSN suppressed invasion and migration of OC cells. Research on molecular mechanism indicated that the above efficacy of TSN was associated with decreased expression of survivin, PARP-1, Bcl-2, Bcl-xl, caspase-3, caspase-9, MMP-2 and MMP-9 and increased expression of cleaved PARP-1, Bax, cleaved caspase-3 and cleaved caspase-9. Finally, in vivo results showed that TSN suppressed OC xenograft tumor growth by inducing apoptosis and regulating the related protein expression levels of SKOV3 cells in transplanted tumors. Taken together, our data provide new insights into TSN as a potentially effective reagent against human OC through caspase-dependent mitochondrial apoptotic pathway.

Apoptin Causes Apoptosis in HepG-2 Cells by Inducing Stress Injury in the Endoplasmic Reticulum

Apoptin is derived from the chicken anemia virus and exhibits specific cytotoxic effects against tumor cells. In our previous study, we demonstrated that Apoptin induced significant changes in the expression levels of endoplasmic reticulum stress (ERS) related proteins and caused a strong and lasting ERS response. The aim of this study was to explore the effects of ERS injury induced by Apoptin on the endoplasmic reticulum (ER) and the apoptotic pathway in mitochondria. ERS injury induced the intracellular levels of calcium (Ca2+) were determined by electron microscopy, flow cytometry and fluorescence staining. Mitochondrial injury was determined by mitochondrial membrane potential and electron microscopy. The relationship between Ca2+ level and mitochondrial injury on Apoptin-treating cells was analyzed using Ca2+ chelator, flow cytometry and fluorescence staining. Western blotting was used to investigate the levels of key proteins in the ER and the apoptotic pathway in mitochondria. We also investigated the in vivo effects of ERS injury on the ER and the mitochondrial apoptotic pathway via the immunohistochemical analysis of tumor tissues from HepG-2 cells acquired from nude mice undergoing xenografts. In vitro and in vivo experiments showed that Apoptin caused ERS injury and an imbalance in Ca2+, damaged the structure of the mitochondria, and increased the expression levels of Caspase-12, CHOP, AIF, HtrA2, Smac/Diablo, and Cyto-C. In summary, Apoptin induced apoptosis in HepG-2 cells via ERS and the mitochondrial apoptotic pathway. This study showed that Apoptin induced apoptosis in HepG-2 cells via ERS injury.

Triclabendazole Induces Pyroptosis by Activating Caspase-3 to Cleave GSDME in Breast Cancer Cells

Pyroptosis is a form of programmed cell death, in which gasdermin E (GSDME) plays an important role in cancer cells, which can be induced by activated caspase-3 on apoptotic stimulation. Triclabendazole is a new type of imidazole in fluke resistance and has been approved by the FDA for the treatment of fascioliasis and its functions partially acting through apoptosis-related mechanisms. However, it remains unclear whether triclabendazole has obvious anti-cancer effects on breast cancer cells. In this study, to test the function of triclabendazole on breast cancer, we treated breast cancer cells with triclabendazole and found that triclabendazole induced lytic cell death in MCF-7 and MDA-MB-231, and the dying cells became swollen with evident large bubbles, a typical sign of pyroptosis. Triclabendazole activates apoptosis by regulating the apoptoic protein levels including Bax, Bcl-2, and enhanced cleavage of caspase-8/9/3/7 and PARP. In addition, enhanced cleavage of GSDME was also observed, which indicates the secondary necrosis/pyroptosis is further induced by active caspase-3. Consistent with this, triclabendazole-induced GSDME–N-terminal fragment cleavage and pyroptosis were reduced by caspase-3–specific inhibitor (Ac-DEVD-CHO) treatment. Moreover, triclabendazole induced reactive oxygen species (ROS) elevation and increased JNK phosphorylation and lytic cell death, which could be rescued by the ROS scavenger (NAC), suggesting that triclabendazole-induced GSDME-dependent pyroptosis is related to the ROS/JNK/Bax-mitochondrial apoptotic pathway. Besides, we showed that triclabendazole significantly reduced the tumor volume by promoting the cleavage of caspase-3, PARP, and GSDME in the xenograft model. Altogether, our results revealed that triclabendazole induces GSDME-dependent pyroptosis by caspase-3 activation at least partly through augmenting the ROS/JNK/Bax-mitochondrial apoptotic pathway, providing insights into this on-the-market drug in its potential new application in cancer treatment.