Abstract
Lung tissue is directly exposed to high oxygen pressure, as well as increased endogenous and exogenous oxidative stress. Reactive oxygen species (ROS) generated in these conditions play an important role in the initiation and promotion of neoplastic growth. In response to oxidative stress, the antioxidant activity increases and minimizes ROS-induced injury in experimental systems. The aim of the present study was to evaluate the activity of antioxidant enzymes, such as superoxide dismutase (SOD; isoforms: Cu/ZnSOD and MnSOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), and glutathione S-transferase (GST), along with the concentration of malondialdehyde (MDA) in tumor and adjacent noncancerous tissues of two histological types of NSCLC, i.e., adenocarcinoma and squamous cell carcinoma, collected from 53 individuals with surgically resectable NSCLC. MDA concentration was similar in tumors compared with adjacent noncancerous tissues. Tumor cells had low MnSOD activity, usually low Cu/ZnSOD activity, and almost always low catalase activity compared with those of the corresponding tumor-free lung tissues. Activities of GSH-related enzymes were significantly higher in tumor tissues, irrespective of the histological type of cancer. This pattern of antioxidant enzymes activity could possibly be the way by which tumor cells protect themselves against increased oxidative stress.
Highlights
During the last ten decades, lung cancer has become one of the most frequently occurring cancers and it is the leading cause of cancer-related death worldwide [1, 2]
The present study aims at evaluating the activity of antioxidant enzymes, such as superoxide dismutase (SOD) (Cu/ZnSOD, and MnSOD), CAT, glutathione peroxidase (GPx), glutathione reductase (GR), and glutathione S-transferase (GST) along with the concentration of MDA in tumor and adjacent noncancerous tissues of two histological types of non-small-cell lung cancer (NSCLC)
No significant differences were observed in the concentrations of MDA and activities of MnSOD and Cu/ZnSOD, while the activities of CAT, GPx, GR, and GST were found to be significantly altered in tumor tissues compared with those in the adjacent noncancerous tissues
Summary
During the last ten decades, lung cancer has become one of the most frequently occurring cancers and it is the leading cause of cancer-related death worldwide [1, 2]. Lung cancer usually originates from the basal epithelial cells and is classified into two types, namely, non-small-cell lung cancer (NSCLC), accounting for approximately 85% of all the cases, and small-cell lung cancer (SCLC), accounting for the remaining 15% of the cases with NSCLC. The lung is directly exposed to high oxygen pressure, environmental irritants, and pollutants including oxidants, Oxidative Medicine and Cellular Longevity such as oxidant gases, ultrafine particulate materials, nanoparticles from industrial pollution, and car exhaust fumes, and smoking, all of which generate free radicals. This results in oxidative stress in the lungs and other organs of the body. The inflammatory response mediated by the inhalation of microbes, mainly viruses and bacteria, is known to be an additional endogenous source of oxidative stress [5, 6]
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