JOURNAL OF IRANIAN CLINICAL RESEARCH *Correspondence: Farideh JalaliMashayekhi, Department of Biochemistry and Genetics, Arak University of Medical Sciences, Arak, Iran, e-mail: mashayekhi@arakmu.ac.ir JICR 2016;2(1): 174-180 ORIGINAL ARTICLE The Effect of Resveratrol on mRNA Levels of DNA polymerase Beta and Oxidative DNA Damage In H2O2- Induced Human Colon Cancer HT-29 Cells Farzane Sadat Shahrokhi 1 , Maryam Baazm 2 , Mohammad Taghi Goodarzi 3 , Ebrahim Eftekhar 4 , Farideh Jalali Mashayekhi 1, 5 1 Department of Biochemistry and Genetics, School of Medicine, Arak University of Medical Sciences, Arak, Iran. 2 Department of Anatomy, School of Medicine, Arak University of Medical Sciences, Arak, Iran. 3 Research Center for Molecular Medicine, Hamadan University of Medical Sciences, Hamadan, Iran. 4 Molecular Medicine Research Center, Department of Biochemistry, School of Medicine, Hormozgan University of Medical Sciences, Bandar Abbas, Iran. 5 Molecular and Medicine Research Center, Arak University of Medical Sciences, Arak, Iran. Keywords: DNA repair enzymes, DNA polymerase beta, DNA damage, Hydrogen peroxide, Resveratrol ABSTRACT Introduction: Resveratrol (3,4,5-trihydroxystilbene), a polyphenol found in high levels in grape skin, has recently attracted huge attention because of its anti- carcinogenic properties. Protective effects of resveratrol against oxidative damage in DNA may be due to its ability to stimulate DNA repair pathways such as the base excision repair (BER). Methods: This study aimed to investigate the effect of resveratrol on gene expression of DNA polymerase beta (DNA pol β), the primary polymerase involved in BER, in H2O2-inducedoxidative human colon cancer HT-29 cells. The 8-oxo-7,8-dihydro-2’- deoxyguanosine (8-OHdG) level and mRNA expression level of DNA polymerase beta (pol β) was measured after human colon cancer HT-29 cells were treated with 100 μM H2O2for 30 min followed by exposure with 75 µM of resveratrol for 48 h. Results: The level of 8-OHdG was significantly increased by H2O2 treatment, but resveratrol pretreatment of cells prior to H2O2 treatment led to a significant reduction of 8-OHdG to the levels similar to those observed in controls. Analysis of qRT -PCR data by one way ANOVA revealed that resveratrol pretreatment also caused a measurable increase in the mRNA expression of DNA polymerase beta (DNA pol β) comparing to that of H2O2-treated and control cells. Conclusion: The cancer-preventive effects of resveratrol may be due in part to stimulation of base excision repair processes. Our data confirm that resveratrol exerts its anti-oxidant and scavenging properties through a reduction in 8-OHdG level. JOURNAL OF IRANIAN CLINICAL RESEARCH 2016;2(1):174-180 INTRODUCTION Increased production of reactive oxygen species (ROS) is one of the main forces driving the onset and progression of cancer [1]. ROS are chemically active molecules generated continuously in cell as natural by products of the normal metabolism of oxygen including the respiratory chain, xanthine oxidase, and cytochrome P450 protein [2, 3]. Additionally, environmental sources such as chemicals and radiation can induce ROS production [4]. Increased levels of ROS production can lead to lipid peroxidation of cellular membranes, oxidative modification of proteins and DNA damage [5]. Single strand breaks (SSB) and double strand DNA breaks (DSB) were considered as the most significant DNA damage. Eight-oxoguanine G (8-OHdG), an oxidized form of guanine, is the most common biomarker for the evaluation of oxidative DNA damage by ROS [6]. Mammalian cells possess several mechanisms to repair DNA damage including direct repair, base excision repair (BER), nucleotide excision repair (NER), mismatch repair (MMR), homologous recombination repair (HR) and non-homologous end joining repair (NHEJ) [7]. Defects in DNA Downloaded from jicr.arakmu.ac.ir at 15:45 +0330 on Sunday October 29th 2017