Understanding Redox Homeostasis and Its Role in Cancer

Abstract

When a cell is damaged or altered without repair to its system, it usually dies. But if such damaged or unrepaired cells do not die and proliferate with uncontrolled growth; a mass of cancer cells develop. Cancer has a complex aetiology with multiple risk factors that involve the interplay between genetic and environmental influences. The redox dysregulation originates from metabolic alterations and it is dependent on mitogenic and survival signalling through reactive oxygen species. There is a delicate balance between the production and the destruction of reactive species; for this, we need to understand the role of redox homeostasis in cancer. So, the specific vulnerability of the malignant cells can be selectively targeted. This article will outline the redox homeostasis and the relationship between the disturbances in it and cancer. InTRoduCTIonRedox (reduction and oxidation) reactions are a family of reactions that are concerned with the transfer of electrons between molecules. Normally, the redox reactions ensure that the cells respond properly to endogenous and exogenous stimuli. During the cellular redox process, Reactive Species -Oxygen (ROS) and nitrogen (RNS)-are liberated as by-products. Lot of research has been directed to understand the beneficial and the deleterious effects of the reactive oxidizing molecules on the human body. An excess of these molecules is commonly referred to as 'Oxidative stress', which can lead to cell damage [1]. This may be one of the factors in the occurrence of many diseases like atherosclerosis, cataract, cardiovascular diseases, Alzheimer's, etc [2][3][4][5][6]. Efforts are also on to design strategies to overcome oxidative stress by using antioxidants.Reactive oxidizing molecules are the molecules with a strong oxidizing property. Free radicals, also called as radicals, are atoms which have unpaired electrons in their outer orbits. Because of this property, they are highly reactive. There are other molecules which lack free electrons in their outer orbits but are highly reactive. These molecules are called as non free radicals.Because of their high reactivities, the free and the non free radicals are collectively called as Reactive Species.Under the normal physiologic conditions, moderate levels of these reactive molecules allow their incorporation into the structure of the macromolecules in a reversible fashion. Such reversible oxidative modifications of lipids, proteins, or DNA play a crucial role in the physiologic processes such as the differentiation, maturation, and trafficking of the intracellular vesicles.ROS and RNS are formed under normal physiological conditions as the products of the cellular metabolism [7]. ROS can be (i) generated during UV light irradiation and by X-rays and gamma rays (ii) produced during metal catalyzed reactions (iii) present in Though many reactive molecules are formed in the body, the Reactive Oxygen Species (ROS) and the Reactive Nitrogen Species (RNS) are the Important ones [Table/ Fig-1]. A delicate balance between the...

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