ABSTRACT
Pyroptosis is an inflammatory form of programmed cell death that plays an important role in regulating tumor progression. Reniformin A (RA) is a natural compound isolated from the medicinal herb Isodon excisoides that has been applied as folk medicine in the treatment of esophageal cancer. However, whether RA has an individual function in cancer and the molecular mechanisms remain unclear. Here, we show that in non-small-cell lung cancer (NSCLC), RA inhibits tumor growth by functioning as a pyroptosis inducer to promote TLR4/NLRP3/caspase-1/GSDMD axis. Specially, RA treatment increased Toll-like receptor 4 (TLR4) protein expression level by enhancing the TLR4 stability. Based on the molecular docking, we identified that RA directly bound to TLR4 to activate the NLRP3 inflammasome and promote pyroptosis in A549 cells. Moreover, TLR4 is essential for RA-induced pyroptosis, and loss of TLR4 abolished RA-induced pyroptosis and further reduced the inhibitory effect of RA on NSCLC. In vivo experiments confirmed that RA inhibited the growth of lung tumors in mice by affecting pyroptosis in a dose-dependent manner. Furthermore, TLR4 knockdown abolished RA-induced pyroptosis and inhibited the effect of RA chemotherapy in vivo. In conclusion, we propose that RA has a significant anticancer effect in NSCLC by inducing TLR4/NLRP3/caspase-1/GSDMD-mediated pyroptosis, which may provide a potential strategy for the treatment of NSCLC.
Subject(s)
Carcinoma, Non-Small-Cell Lung , Lung Neoplasms , Pyroptosis , Animals , Humans , Mice , A549 Cells , Carcinoma, Non-Small-Cell Lung/drug therapy , Carcinoma, Non-Small-Cell Lung/metabolism , Carcinoma, Non-Small-Cell Lung/pathology , Caspase 1/metabolism , Disease Progression , Gasdermins , Intracellular Signaling Peptides and Proteins/metabolism , Intracellular Signaling Peptides and Proteins/genetics , Lung Neoplasms/drug therapy , Lung Neoplasms/pathology , Lung Neoplasms/metabolism , Mice, Inbred C57BL , NLR Family, Pyrin Domain-Containing 3 Protein/metabolism , Phosphate-Binding Proteins/metabolism , Phosphate-Binding Proteins/genetics , Pyroptosis/drug effects , Signal Transduction/drug effects , Toll-Like Receptor 4/metabolismABSTRACT
Eucommia ulmoides leaves are widely developed as food and medicines in China and Japan. Its main components have anti-inflammatory properties against gastric ulcers. The purpose of this study was to assess the protective role of an extract derived from the active components of Eucommia ulmoides leaves (EUL 50) against a gastric ulcer and analyze the underlying antiulcer mechanism. The main components of EUL 50 were identified using an ultra-performance liquid chromatography (UPLC) method. Network pharmacology and molecular docking were performed to predict the possible mechanism of action of EUL 50 in the treatment of gastric ulcers. The rats received EUL 50 intragastric administration twice a day for 3 days. Hydrochloric acid/ethanol (HCl/EtOH) was utilized to induce gastric ulcers, followed by histopathological and histochemical evaluation of the ulcer tissues and determination of the main oxidative stress parameters and inflammatory cytokines. The expression of PI3K/Akt/NF-κB pathway-related proteins was measured. Neochlorogenic acid, chlorogenic acid, rutin, and so on were identified as the major components of EUL 50 by UPLC. The prediction results identified the PI3K/Akt/NF-κB signaling pathway as the main possible protective mechanism against gastric ulcers. Furthermore, in a dose-dependent manner, EUL 50 reduced gastric tissue damage. In addition, the high dose of EUL 50 administration resulted in remarkable reductions in the levels of malondialdehyde (MDA), tumor necrosis factor α (TNF-α), interleukin 6 (IL-6), and interleukin-1ß (IL-1ß) by 22.64%, 42.61%, 57.78%, and 56.51%, respectively, and suppression of the phosphorylation of Akt, p65, IKKα, and IκBα by 60.87%, 67.65, 74.58%, and 59.57%, respectively, and increased the antioxidant enzyme activity. EUL 50 is rich in flavonoids and organic acids that can act on the PI3K/Akt/NF-κB signaling pathway; as a result, oxidative stress and inflammation are considerably reduced, and gastric ulcers caused by HCl/EtOH are reduced. PRACTICAL APPLICATION: As a medicinal and food substance, Eucommia ulmoides leaves are widely used in the development of health products. EUL 50, a moderately polar part of E. ulmoides leaves, was obtained by extraction and enrichment and was found to have a better protective effect against HCl/EtOH-induced gastric ulcers. This finding can enrich the traditional application of E. ulmoides leaves and provide a basis for their health product development.