Previous research has identified that air pollution is associated with various respiratory diseases, but few studies have investigated the function served by particulate matter 2.5 (PM2.5) in these diseases. PM2.5 is known to cause epigenetic and microenvironmental alterations in lung cancer, including tumor-associated signaling pathway activation mediated by microRNA dysregulation, DNA methylation, and increased levels of cytokines and inflammatory cells. Autophagy and apoptosis of tumor cells may also be detected in lung cancer associated with PM2.5 exposure. A number of mechanisms are involved in triggering and aggravating asthma and COPD, including PM2.5-induced cytokine release and oxidative stress. The present review is an overview of the underlying molecular mechanisms of PM2.5-induced pathogenesis in lung cancer and chronic airway inflammatory diseases.
Chalocomoracin (CMR), one of the major secondary metabolites found in fungus-infected mulberry leaves, is a potent anticancer agent. However, its anticancer mechanism remains elusive. Here, we demonstrated the potent anti-tumor activity and molecular mechanism of CMR both in vitro and in vivo. We showed for the first time that CMR treatment markedly promoted paraptosis along with extensive cytoplasmic vacuolation derived from the endoplasmic reticulum, rather than apoptosis, in PC-3 and MDA-MB-231cell lines. Additional studies revealed that ectopic expression of Myc-PINK1 (PTEN-induced kinase 1), a key regulator of mitophagy, rendered LNCap cells susceptible to CMR-induced paraptosis, suggesting that the mitophagy-dependent pathway plays a crucial role in inducing paraptosis by activating PINK1. CMR treatment directly upregulated PINK1 and downregulated Alix genes in MDA-MB-231 and PC-3 cell lines. Furthermore, mitophagy signaling and paraptosis with cytoplasmic vacuolation could be blocked by antioxidant N-acetylcysteine (NAC), indicating the novel pathway was triggered by reactive oxygen species (ROS) production. An in vivo MDA-MB-231 xenograft tumor model revealed that CMR suppressed tumor growth by inducing vacuolation production through the same signal changes as those observed in vitro. These data suggest that CMR is a potential therapeutic entity for cancer treatment through a non-apoptotic pathway.
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