BH3-Dependent and Independent Activation of BAX and BAK in Mitochondrial Apoptosis

Seneca Valley Virus 2C and 3Cpro Induce Apoptosis via Mitochondrion-Mediated Intrinsic Pathway

Seneca Valley virus (SVV) is the only member of the genus Senecavirus of the Picornaviridae family. SVV can selectively infect and lyse tumor cells with neuroendocrine features and is used as an oncolytic virus for treating small-cell lung cancers. However, the detailed mechanism underlying SVV-mediated destruction of tumor cells remains unclear. In this study, we found that SVV can increase the proportion of apoptotic 293T cells in a dose- and time-dependent manner. SVV-induced apoptosis was initiated via extrinsic and intrinsic pathways through activation of caspase-3, the activity of which could be attenuated by a pan-caspase inhibitor (Z-VAD-FMK). We confirmed that SVV 2C and 3C^pro play critical roles in SVV-induced apoptosis. The SVV 2C protein was located solely in the mitochondria and activated caspase-3 to induce apoptosis. SVV 3C^pro induced apoptosis through its protease activity, which was accompanied by release of cytochrome C into the cytoplasm, but did not directly cleave PARP1.

Countering TRAIL Resistance in Melanoma

Melanoma of the skin has become a prime example for demonstrating the success of targeted cancer therapy. Nevertheless, high mortality has remained, mainly related to tumor heterogeneity and inducible therapy resistance. But the development of new therapeutic strategies and combinations has raised hope of finally defeating this deadly disease. TNF-related apoptosis-inducing ligand (TRAIL) represents a promising antitumor strategy. The principal sensitivity of melanoma cells for TRAIL was demonstrated in previous studies; however, inducible resistance appeared as a major problem. To address this issue, combination strategies were tested, and survival pathway inhibitors were shown to sensitize melanoma cells for TRAIL-induced apoptosis. Finally, cell cycle inhibition was identified as a common principle of TRAIL sensitization in melanoma cells. Mitochondrial apoptosis pathways, pro- and antiapoptotic Bcl-2 proteins as well as the rheostat consisted of Smac (Second mitochondria-derived activator of caspase) and XIAP (X-linked inhibitor of apoptosis protein) appeared to be of particular importance. Furthermore, the role of reactive oxygen species (ROS) was recognized in this setting. Inducible TRAIL resistance in melanoma can be explained by (i) high levels of antiapoptotic Bcl-2 proteins, (ii) high levels of XIAP, and (iii) suppressed Bax activity. These hurdles have to be overcome to enable the use of TRAIL in melanoma therapy. Several strategies appear as particularly promising, including new TRAIL receptor agonists, Smac and BH3 mimetics, as well as selective kinase inhibitors.

Biosynthesis, characterization, and anticancer effect of plant-mediated silver nanoparticles using Coptis chinensis

Background

Tremendous growth in nanotechnology has opened up new frontiers in fundamental and applied aspects, including the synthesis of nanoscale matter and understanding/utilizing its exotic physicochemical and optoelectronic properties. Green-synthesis methods employing either biological microorganisms or plant extracts have emerged as a simple and alternative to chemical synthesis.

Methods

In our present study, we aimed to synthesize silver nanoparticles (AgNPs) in combination with an aqueous extract of Coptis chinensis (CC) using a suitable ecofriendly green-synthesis way.

Results

In our results, ultraviolet-visible spectroscopy revealed a near-absorbance peak at 450 nm, which confirmed the AgNP synthesis. The crystalline nature of the AgNPs was revealed with X-ray diffraction. Transmission electron-microscopy analysis showed spherically dispersed nanoparticles of 6–45 nm diameter. We analyzed the elementary mechanism across A549 lung carcinoma cells ahead of treatment with doses of CC-AgNPs (10 µg/mL and 25 µg/mL). The antiproliferative effect of CC-AgNPs revealed a significant decline in cell viability. Antibacterial assays with both Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria exhibited a higher zone of inhibition against S. aureus.

Conclusion

Furthermore, CC-AgNPs regulated apoptosis using the intrinsic pathway to inhibit A549-cell proliferation. Proliferation migration and invasion were notably inhibited by CC-AgNPs, which promoted apoptosis in lung adenocarcinoma cells by regulating the apoptotic pathway.