Oxidant and Antioxidant Activity Alteration in Anaplastic Astrocytomas Patients Following Radiation Therapy

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Oxidant and Antioxidant Activity Alteration in Anaplastic Astrocytomas Patients Following Radiation Therapy

Journal Title: Journal of Medical Science And clinical Research - Year 2014, Vol 2, Issue 5

Abstract

Radiation therapy has been used in cancer treatment for many decades, although effective in killing tumor cells, ROS produced in radiotherapy threaten the integrity and survival of surrounding normal cells. Radiation damages cell by direct ionization of DNA and and other cellular targets and by indirect effect through ROS. A linkage between an increase in cellular ROS and the pathogenesis of several chronic diseases including cancer has been established. When the antioxidants control Mayank Baranwal et al JMSCR Volume 2 Issue 5 May 2014 Page 1195 JMSCR Volume||2||Issue||5||Page 1194-1203 ||May 2014 2014 INTRODUCTION Cancer is the second leading cause of death worldwide. It is estimated that there are approximately 2-2.5 million cases of cancer in India at any given point of time, with around 700,000 new cases being detected every year [1]. Radiation therapy has been used in cancer treatment for many decades; it is used to eradicate cancer and as a palliative to relieve pain associated with metastases. In the course of treatment, radiation produces numerous biological perturbations in cells; because normal cell toxicity limits the doses used in effective treatment, approaches are designed to strike a balance between eliminating cancer cells and protecting normal tissues [2]. The biological effects they produce are thought mainly to be caused by the production of free radicals from interaction with the cell constituents, especially water [3]. Oxygen, normally present in most biological systems, aggravates the damage done by radiation. Reactive oxygen species (ROS) are produced by living organisms as a result of normal cellular metabolism and environmental factors, such as air pollutants or cigarette smoke. ROS are highly reactive molecules and can damage cell structures such as carbohydrates, nucleic acids, lipids, and proteins and alter their functions. The shift in the balance between oxidants and antioxidants in favor of oxidants is termed “oxidative stress” [4]. Ionizing radiation, in the presence of O2, converts hydroxyl radical, superoxide, and organic radicals to hydrogen peroxide and organic hydroperoxides. mechanisms are exhausted or overrun, the control redox potential shifts towards oxidative stress, in turn increasing the potential for damage to nucleic acids, lipids and proteins. Human cells normally function in a reduced state, but oxidative stress results in imbalance towards a more oxidised state resulting in lower levels of antioxidants. In the present study the damage caused by ROS and the effect of radiation in anaplastic astrocytomas (WHO grade III) patients were assessed by analyzing MDA levels, GPX and GR activities. Blood samples were collected before and after radiation treatment. The MDA levels showed a highly significant elevation both before and after radiotherapy which reflects increased lipid peroxidation. The activity of antioxidant enzymes GPx and GR were found to be decreased highly significantly in same patients before and after radiotherapy when compared to healthy controls which showed the lack of antioxidant defense. Radiation induces lipid peroxidation by inactivating the antioxidant enzymes, thereby rendering the system in management of the free radical attack. Hence the degree of radiation affects the extent of the depression of the antioxidant enzyme activities and increased lipid peroxidation.

Authors and Affiliations

Mayank Baranwal

Keywords

EP ID EP205921
DOI -
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