en Cell, Stem Cell and Cancer Cell, Stem Cell and Cancer Experimental research article Experimental research article <div style="text-align: justify;"><strong>Introduction:</strong> Nowadays, the prevalence of nicotine abuse among women has increased dramatically. In the current study, we aimed to investigate the effect of nicotine exposure on breast MCF-7 and ovarian OVCAR-3 cell lines for assessing the toxicity of nicotine in the cells of these organs. <strong>Methods: </strong>The MCF-7 and OVCAR-3 cells were treated with increasing nicotine concentrations ranging from 0 (control), 10-11, 10-8 and 10-6 M for 24h. Effect of nicotine treatments on major antioxidant enzymes catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), cellular levels of glutathione (GSH) and malondialdehyde (MDA) were monitored. <strong>Results: </strong>We showed that the CAT activity in MCF-7 cells increased only at 10-6 M dose of nicotine. The GPx and GR activity was decreased at 10-8 and 10-6 M of nicotine in MCF-7 cells, but in OVCAR-3 cells, this decrease was significant only at 10-6 M dose of nicotine. Reduced GSH decrease was statistically significant only at 10-8 and 10-6 M of nicotine in MCF-7 cells; otherwise, in OVCAR-3 cells, this decline was significant only at 10-6 M of nicotine. Nicotine at 10-8 and 10-6 M concentration caused a significant increase in MDA levels in MCF-7 cells. <strong>Conclusion: </strong>This study showed that breast MCF-7 cells are more vulnerable than ovarian OVCAR-3 cells against nicotine-induced oxidative toxicity.</div> Nicotine, Antioxidant enzymes, Oxidative stress, MCF-7 cells, OVCAR-3 cells. 279 287 http://ppj.phypha.ir/browse.php?a_code=A-10-1357-1&slc_lang=en&sid=1 Amir Yarahmadi 3200319475328460029311 3200319475328460029311 No Department of Biochemistry, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran Neda Mohammadi 3200319475328460029312 3200319475328460029312 No Department of Biochemistry, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran Fatemeh Zal Fatemehzal@sums.ac.ir 3200319475328460029313 3200319475328460029313 Yes Department of Biochemistry, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran