Effect of glutathione reductase knockdown in response to UVB-induced oxidative stress in human lung adenocarcinoma

Unveiling the Synergistic Role of Oxygen Functional Groups in the Graphene-Mediated Oxidation of Glutathione

This is the first report of an atomic-scale direct oxidation mechanism of the thiol group in glutathione (GSH) by epoxides on graphene oxide (GO) at room temperature. The proposed reaction mechanism is determined using a coupled experimental and computational approach; active sites for the reaction are determined through examination of GO surface chemistry changes before and after exposure to GSH, and density functional theory (DFT) calculations determine the reaction barriers for the possible GO-GSH reaction schemes. The findings build on the previously established catalytic mechanism of GSH oxidation by graphenic nanocarbon surfaces and importantly identify the direct reaction mechanism which becomes important in low-oxygen environments. Experimental results suggest epoxides as the active sites for the reaction with GSH, which we confirm using DFT calculations of reaction barriers and further identify a synergism between the adjacent epoxide and hydroxyl groups on the GO surface. The direct oxidation mechanism at specific oxygen sites offers insight into controlling GO chemical reactivity through surface chemistry manipulations. This insight is critical for furthering our understanding of GO oxidative stress pathways in cytotoxicity as well as for providing rational material design for GO applications that can leverage this reaction.

Chemical and Colloidal Dynamics of MnO2 Nanosheets in Biological Media Relevant for Nanosafety Assessment

Many layered crystal phases can be exfoliated or assembled into ultrathin 2D nanosheets with novel properties not achievable by particulate or fibrous nanoforms. Among these 2D materials are manganese dioxide (MnO2 ) nanosheets, which have applications in batteries, catalysts, and biomedical probes. A novel feature of MnO2 is its sensitivity to chemical reduction leading to dissolution and Mn2+ release. Biodissolution is critical for nanosafety assessment of 2D materials, but the timing and location of MnO2 biodissolution in environmental or occupational exposure scenarios are poorly understood. This work investigates the chemical and colloidal dynamics of MnO2 nanosheets in biological media for environmental and human health risk assessment. MnO2 nanosheets are insoluble in most aqueous phases, but react with strong and weak reducing agents in biological fluid environments. In vitro, reductive dissolution can be slow enough in cell culture media for MnO2 internalization by cells in the form of intact nanosheets, which localize in vacuoles, react to deplete intracellular glutathione, and induce cytotoxicity that is likely mediated by intracellular Mn2+ release. The results are used to classify MnO2 nanosheets within a new hazard screening framework for 2D materials, and the implications of MnO2 transformations for nanotoxicity testing and nanosafety assessment are discussed.

Increased levels of the long noncoding RNA, HOXA-AS3, promote proliferation of A549 cells

Many long noncoding RNAs (lncRNAs) have been identified as powerful regulators of lung adenocarcinoma (LAD). However, the role of HOXA-AS3, a novel lncRNA, in LAD is largely unknown. In this study, we showed that HOXA-AS3 was significantly upregulated in LAD tissues and A549 cells. After knockdown of HOXA-AS3, cell proliferation, migration, and invasion were inhibited. Xenografts derived from A549 cells transfected with shRNA/HOXA-AS3 had significantly lower tumor weights and smaller tumor volumes. We also demonstrated that HOXA-AS3 increased HOXA6 mRNA stability by forming an RNA duplex. In addition, HOXA6 promoted cell proliferation, migration, and invasion in vitro. Using a RNA pull-down assay, we found that HOXA-AS3 bonded with NF110, which regulated the cell localization of HOXA-AS3. Moreover, histone acetylation was involved in upregulation of HOXA-AS3. These results demonstrate that HOXA-AS3 was activated in LAD and supported cancer cell progression. Therefore, inhibition of HOXA-AS3 could be an effective targeted therapy for patients with LAD.

Enhanced expression of long non-coding RNA ZXF1 promoted the invasion and metastasis in lung adenocarcinoma

The identification of cancer-associated long non-coding RNAs (LncRNA) and the investigation of their molecular and biological functions are important for understanding the molecular biology and progression of cancer. This study aims to find the key LncRNA associated with lung adenocarcinoma and to evaluate its biological role and clinical significance in tumor progression. Microarray analysis of 32,756 LncRNA was performed to screen the significantly different LncRNA between human lung adenocarcinoma tissues and adjacent non-cancerous lung tissues, which was named as LncRNA ZXF1. Expression of LncRNA ZXF1 was analyzed in 62 lung adenocarcinoma tissues and adjacent non-cancerous lung tissues by quantitative reverse-transcription PCR (qRT-PCR). Correlations between LncRNA ZXF1 expression and the clinicopathological features and prognosis of patients were also analyzed. The inhibition of LncRNA ZXF1 using siRNA treatment was performed in order to explore its role in tumor progression. The effect of LncRNA ZXF1 on proliferation was evaluated by CCK-8 assay using A549 cell lines, and cell migration and invasion were detected by transwell assays. Here we found that LncRNA ZXF1 levels were remarkably increased in lung adenocarcinoma tissues compared with adjacent non-cancerous lung tissues (P<0.05), and up-regulated LncRNA ZXF1 was correlated with lymph node metastasis (P<0.05), tumor pathological stage (P<0.05) and the extent of lymph node metastasis (correlation coefficient=0.366). The 3-year overall survival rate of patients with higher LncRNA ZXF1 levels was remarkably reduced compared with patients with lower LncRNA ZXF1 levels, implying that patients with high levels of LncRNA ZXF1expression had a relatively poor prognosis. Inhibition of LncRNA ZXF1 by siRNA decreased the migration and invasion of A549 cells in vitro, while there was no significant effect in cell proliferation.

Phytoremediation potential of Maná-Cubiu (Solanum sessiliflorum Dunal) for the deleterious effects of methylmercury on the reproductive system of rats

Methylmercury, organic form of mercury, can increase the number of abnormal sperm and decrease sperm concentration and testosterone levels possibly due to the damage caused by reactive species to germ and Leydig cells. Maná-cubiu (Solanum sessiliflorum Dunal) is a native fruit from Amazon rich in iron, zinc, niacin, pectin, and citric acid, used in foods, beverages, and medicinal purposes, since it has been useful for treatment of various diseases caused by oxidative stress or nutritional deficiency. Therefore, this study evaluated the phytoremediation potential of this fruit on damages caused by exposure to MeHg on sperm quantity and quality and the histological aspect of the testis and epididymis. Wistar male rats (n = 20) were randomly allocated into four groups: Control group (received distilled water), MeHg group (140 μg/Kg), Solanum group (1% of fruit Maná-cubiu on chow), and Solanum plus MeHg group (same treatment as MeHg and Solanum group). The organs were weighted, histopathology; sperm morphology and counts were obtained. The results showed reduction in body weight gain, testis weights, reduced sperm production, and increased histopathological abnormalities in the MeHg-treated group. However, treatment with Solanum plus MeHg revealed a protective effect of this fruit on damages caused by MeHg.