NO center dot and Pancreatic Cancer: A Complex Interaction with Therapeutic Potential
ANTIOXIDANTS & REDOX SIGNALING
Authors: Wang, Jian; Hussain, S. Perwez
Abstract
Significance: Pancreatic tumors express high level of nitric oxide synthases (NOSs) in particular inducible (iNOS/NOS2) and endothelial (eNOS/NOS3) forms. However, the role of nitric oxide (NO center dot) in the development and progression of pancreatic cancer is not clearly defined. Delineating the NO center dot- induced signaling in pancreatic cancer and its potential contribution in disease aggressiveness may provide therapeutic targets to improve survival in this lethal malignancy. Recent Advances: An increased expression of NOS2/iNOS in tumors is associated with poorer survival in early stage resected patients with pancreatic ductal adenocarcinoma (PDAC). Furthermore, genetic deletion of NOS2 enhanced survival in mice with autochthonous PDAC. Additionally, targeting NOS3/eNOS reduced the abundance of precursor lesions in mice, which trended toward improved survival. Critical Issues: The extremely poor prognosis in pancreatic cancer is due to the late diagnosis and lack of effective therapy in advanced disease. One of the most critical issues is to decipher the underlying mechanism of disease aggressiveness and therapeutic resistance for identifying potential therapeutic target and effective treatment. Given the evidence of a strong association between inflammation and pancreatic cancer and clinical evidence, which suggests an association between NOS2 and disease aggressiveness, it is critical to define the role of NO center dot signaling in this lethal malignancy. Future Directions: Recent preclinical and clinical evidences indicate a potential therapeutic significance of targeting NO center dot signaling in pancreatic cancer. With the emergence of new preclinical models, including the patient-derived organoids, further preclinical evaluation using clinically tested NOS inhibitors is needed for designing future clinical investigation.
Metal rich particulate matter impairs acetylcholine-mediated vasorelaxation of microvessels in mice
PARTICLE AND FIBRE TOXICOLOGY
Authors: Cuevas, Azita K.; Niu, Jingping; Zhong, Mianhua; Liberda, Eric N.; Ghio, Andrew; Qu, Qingshan; Chen, Lung Chi
Abstract
Background: Exposure to PM2.5 (particulate matter <2.5 mu m) has been associated with changes in endothelial function. PM2.5 was collected from two Chinese cities, Jinchang (JC) and Zhangye (ZH), both with similar PM2.5 concentrations. However, JC had levels of nickel (Ni), selenium (Se), copper (Cu), and arsenic (As) that were 76, 25, 17, and 7 fold higher than that measured in ZH, respectively. We used this unique PM sample to delineate the chemical components that drive pulmonary and systemic effects and explore the mechanism(s) by which vascular dysfunction is caused. Methods: Male FVB/N mice received oropharyngeal aspiration of water or PM2.5 from JC, ZH or ZH spiked with one of the following elements at the same concentrations found in the JC PM (Ni = 4.76; As = 2.36; Se = 0.24; Cu = 2.43 mu g/mg) followed by evaluation of markers of pulmonary and systemic inflammation. Mesenteric arteries were isolated for gene expression or functional response to various agonists (Phenylephrine, Acetylcholine, and Sodium Nitroprusside) and inhibitors (L-NAME, Apocynin, and VAS2870) ex vivo. Results: Protein and total cell counts from lung lavage revealed significant pulmonary inflammation from ZH (p < 0.01) and JC and ZH + NiSO4 (p < 0.001) as compared to control and a significant decrease in mesenteric artery relaxation (p < 0.001) and this decrease is blunted in the presence of NADPH oxidase inhibitors. Significant increases in gene expression (TNF-alpha, IL-6, Nos3; p < 0.01; NOX4; p < 0.05) were observed in JC and ZH + NiSO4, as well as significantly higher concentrations of VEGF and IL-10 (p < 0.01, p < 0.001; respectively). Conclusions: Our results indicate that the specific toxicity observed in PM from JC is likely due to the nickel component in the PM. Further, since VAS2870 was the most successful inhibitor to return vessels to baseline relaxation values, NADPH Oxidase is implicated as the primary source of PM-induced O-2(center dot-).