%0 Journal Article
%T Against Lung Cancer Cells: To Be, or Not to Be, That Is the Problem
%A Naoko Okumura
%A Hitomi Yoshida
%A Yasuko Kitagishi
%A Yuri Nishimura
%A Shio Iseki
%A Satoru Matsuda
%J Lung Cancer International
%D 2012
%I Hindawi Publishing Corporation
%R 10.1155/2012/659365
%X Tobacco smoke and radioactive radon gas impose a high risk for lung cancer. The radon-derived ionizing radiation and some components of cigarette smoke induce oxidative stress by generating reactive oxygen species (ROS). Respiratory lung cells are subject to the ROS that causes DNA breaks, which subsequently bring about DNA mutagenesis and are intimately linked with carcinogenesis. The damaged cells by oxidative stress are often destroyed through the active apoptotic pathway. However, the ROS also perform critical signaling functions in stress responses, cell survival, and cell proliferation. Some molecules enhance radiation-induced tumor cell killing via the reduction in DNA repair levels. Hence the DNA repair levels may be a novel therapeutic modality in overcoming drug resistance in lung cancer. Either survival or apoptosis, which is determined by the balance between DNA damage and DNA repair levels, may lender the major problems in cancer therapy. The purpose of this paper is to take a closer look at risk factor and at therapy modulation factor in lung cancer relevant to the ROS. 1. Introduction Lung cancer is the commonest fatal cancer whose risk is dependent on the number of cigarettes smoked per day as well as the duration years of the smoking [1, 2]. Passive smoking also damages health [3]. Cigarette smoke is a complex mixture of more than 5000 chemicals that have been identified in the smoke. Among them, more than 50 are known to cause cancer in humans. A wide variety of the other toxic substances such as asbestos, polycyclic aromatic carbohydrates, arsenic, and diesel emissions also have been identified as potential causes of lung cancer [4, 5]. Some of these carcinogens react covalently with DNA to cause oxidative damage, which can induce DNA breaks [6]. Another recognized lung carcinogen is the chemically nearly inert gas radon [7], a ubiquitous natural air pollutant arising from radioactive decay of the uranium-238, which is present throughout the earth crust. Radon is a naturally occurring radioactive gas with the atomic number 86. It is odorless and colorless. Both radon-induced ionizing radiation and some components of cigarette smoke induce oxidative stress by transmitting or generating reactive oxygen species (ROS). The chronic exposure to ROS contributes to a variety of processes, including aging, degenerative diseases, and cancer [8]. ROS also appear to play an essential role as secondary messengers in the normal regulation of a variety of physiological processes, such as apoptosis, survival, and proliferative signaling pathways [9,
%U http://www.hindawi.com/journals/lci/2012/659365/