Almost all human diseases are strongly associated with inflammation, and a deep understanding of the exact mechanism is helpful for treatment. The NLRP3 inflammasome composed of the NLRP3 protein, procaspase-1, and ASC plays a vital role in regulating inflammation. In this review, NLRP3 regulation and activation, its proinflammatory role in inflammatory diseases, interactions with autophagy, and targeted therapeutic approaches in inflammatory diseases will be summarized.
Ferroptosis is a new form of regulated cell death that is mediated by intracellular iron and ester oxygenase, and glutathione-dependent lipid hydroperoxidase glutathione peroxidase 4 (GPX4) prevents ferroptosis by converting lipid hydroperoxides into nontoxic lipid alcohols. Although thiostrepton (TST) has been reported to exert antitumor effects, its role in pancreatic cancer and the underlying mechanisms remain unclear. In this study, we found that TST reduced the viability and clonogenesis of pancreatic cancer cell lines, along with intracellular iron overload, increasing reactive oxygen species (ROS) accumulation, malondialdehyde (MDA) overexpression, and glutathione peroxidase (GSH-PX) depletion. Mechanistically, chromatin immunoprecipitation (ChIP) and dual luciferase reporter gene assays were used to confirm that signal transducer and activator of transcription 3 (STAT3) binds to the GPX4 promoter region and promotes its transcription, whereas TST blocked GPX4 expression by regulating STAT3. Finally, in vivo experiments revealed that TST inhibited the growth of subcutaneously transplanted tumours and had considerable biosafety. In conclusion, our study identified the mechanism by which TST-induced ferroptosis in pancreatic cancer cells through STAT3/GPX4 signalling.
Background
Perineural invasion (PNI) and autophagy are two common features in the tumor microenvironment of pancreatic cancer (PanCa) and have a negative effect on prognosis. Potential mediator cells and the molecular mechanism underlying their relationships need to be fully elucidated.
Methods
To investigate the autophagy of Schwann cells (SCs) in PNI, we reproduced the microenvironment of PNI by collecting clinical PNI tissue, performing sciatic nerve injection of nude mice with cancer cells and establishing a Dorsal root ganglion (DRG) coculture system with cancer cell lines. Autophagy was detected by IHC, IF, transmission electron microscopy (TEM) and western blotting assays. Apoptosis was detected by IF, TEM and western blotting. NGF targeting molecular RO 08–2750(RO) and the autophagy inhibitor Chloroquine (CQ) were utilized to evaluate the effect on autophagy and apoptosis in SCs and PanCa cells in PNI samples.
Results
SC autophagy is activated in PNI by paracrine NGF from PanCa cells. Autophagy-activated Schwann cells promote PNI through a) enhanced migration and axon guidance toward PanCa cells and b) increased chemoattraction to PanCa cells. The NGF-targeting reagent RO and autophagy inhibitor CQ inhibited Schwann cell autophagic flux and induced Schwann cell apoptosis. Moreover, RO and CQ could induce PanCa cell apoptosis and showed good therapeutic effects in the PNI model.
Conclusions
PanCa cells can induce autophagy in SCs through paracrine pathways such as the NGF/ATG7 pathway. Autophagic SCs exert a “nerve-repair like effect”, induce a high level of autophagy of cancer cells, provide a “beacon” for the invasion of cancer cells to nerve fibers, and induce directional growth of cancer cells. Targeting NGF and autophagy for PNI treatment can block nerve infiltration and is expected to provide new directions and an experimental basis for the research and treatment of nerve infiltration in pancreatic cancer.
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