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Lv X, Xu G. Regulatory role of the transforming growth factor-β signaling pathway in the drug resistance of gastrointestinal cancers. World J Gastrointest Oncol 2021; 13:1648-1667. [PMID: 34853641 PMCID: PMC8603464 DOI: 10.4251/wjgo.v13.i11.1648] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 06/28/2021] [Accepted: 08/18/2021] [Indexed: 02/06/2023] Open
Abstract
Gastrointestinal (GI) cancer, including esophageal, gastric, and colorectal cancer, is one of the most prevalent types of malignant carcinoma and the leading cause of cancer-related deaths. Despite significant advances in therapeutic strategies for GI cancers in recent decades, drug resistance with various mechanisms remains the prevailing cause of therapy failure in GI cancers. Accumulating evidence has demonstrated that the transforming growth factor (TGF)-β signaling pathway has crucial, complex roles in many cellular functions related to drug resistance. This review summarizes current knowledge regarding the role of the TGF-β signaling pathway in the resistance of GI cancers to conventional chemotherapy, targeted therapy, immunotherapy, and traditional medicine. Various processes, including epithelial-mesenchymal transition, cancer stem cell development, tumor microenvironment alteration, and microRNA biogenesis, are proposed as the main mechanisms of TGF-β-mediated drug resistance in GI cancers. Several studies have already indicated the benefit of combining antitumor drugs with agents that suppress the TGF-β signaling pathway, but this approach needs to be verified in additional clinical studies. Moreover, the identification of potential biological markers that can be used to predict the response to TGF-β signaling pathway inhibitors during anticancer treatments will have important clinical implications in the future.
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Affiliation(s)
- Xiaoqun Lv
- Department of Pharmacy, Jinshan Hospital, Fudan University, Shanghai 201508, China
| | - Guoxiong Xu
- Research Center for Clinical Medicine, Jinshan Hospital, Fudan University, Shanghai 201508, China
- Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, China
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Demicheli V, Moreno DM, Radi R. Human Mn-superoxide dismutase inactivation by peroxynitrite: a paradigm of metal-catalyzed tyrosine nitration in vitro and in vivo. Metallomics 2018; 10:679-695. [DOI: 10.1039/c7mt00348j] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Nitration of human MnSOD at active site Tyr34 represents a biologically-relevant oxidative post-translational modification that causes enzyme inactivation.
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Affiliation(s)
- Verónica Demicheli
- Departmento de Bioquimica
- Facultad de Medicina
- Center for Free Radical and Biomedical Research
- Universidad de la República
- Montevideo
| | - Diego M. Moreno
- Instituto de Química Rosario (IQUIR, CONICET-UNR)
- Área Química General e Inorgánica
- Facultad de Ciencias Bioquímicas y Farmacéuticas
- Universidad Nacional de Rosario
- Argentina
| | - Rafael Radi
- Departmento de Bioquimica
- Facultad de Medicina
- Center for Free Radical and Biomedical Research
- Universidad de la República
- Montevideo
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Wang R, Yin C, Li XX, Yang XZ, Yang Y, Zhang MY, Wang HY, Zheng XFS. Reduced SOD2 expression is associated with mortality of hepatocellular carcinoma patients in a mutant p53-dependent manner. Aging (Albany NY) 2017; 8:1184-200. [PMID: 27221200 PMCID: PMC4931826 DOI: 10.18632/aging.100967] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Accepted: 05/10/2016] [Indexed: 02/07/2023]
Abstract
The development and progression of hepatocellular carcinoma (HCC) is accompanied with persistent oxidative stress, but the molecular basis is not well defined. Superoxide dismutase 2 (SOD2) is an important mitochondrial antioxidant and a key aging factor. Here we investigated the expression and clinical significance of SOD2 in a large cohort of HBV-positive HCC tumors. Both SOD2 mRNA and protein are reduced in human primary HCCs compared with matching liver tissues. Consistently, the SOD2 DNA copy numbers are decreased in HCCs, providing a genetic basis for the decrease in SOD2 mRNA expression. Reduced SOD2 expression in HCCs is correlated with older age, larger tumor size, multiple tumor nodules and tumor emboli, and cancer recurrence. Moreover, low SOD2 expression is strongly associated with poor overall survival (OS) and recurrence-free survival (RFS). Univariate and multivariate Cox regression analyses indicates that SOD2 is an independent prognostic predictor for OS and RFS. Intriguingly, reduced SOD2 mRNA is strongly associated with poor survival in a separate cohort of HCC patients carrying mutant p53. Altogether, our results provide clinical evidence for the importance of SOD2 in tumor progression and mortality, and the close relationship of SOD2 and p53 in HCC.
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Affiliation(s)
- Ren Wang
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-Sen University Cancer Center, Guangzhou, 510060, PR China
| | - Chen Yin
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-Sen University Cancer Center, Guangzhou, 510060, PR China
| | - Xiao-Xing Li
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-Sen University Cancer Center, Guangzhou, 510060, PR China
| | - Xian-Zi Yang
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-Sen University Cancer Center, Guangzhou, 510060, PR China
| | - Yang Yang
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-Sen University Cancer Center, Guangzhou, 510060, PR China
| | - Mei-Yin Zhang
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-Sen University Cancer Center, Guangzhou, 510060, PR China
| | - Hui-Yun Wang
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-Sen University Cancer Center, Guangzhou, 510060, PR China.,Rutgers Cancer Institute of New Jersey, and Department of Pharmacology, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, New Brunswick, NJ 08903, USA
| | - X F Steven Zheng
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-Sen University Cancer Center, Guangzhou, 510060, PR China.,Rutgers Cancer Institute of New Jersey, and Department of Pharmacology, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, New Brunswick, NJ 08903, USA
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Immunohistochemical assessment of mitochondrial superoxide dismutase (MnSOD) in colorectal premalignant and malignant lesions. GASTROENTEROLOGY REVIEW 2016; 11:239-246. [PMID: 28053678 PMCID: PMC5209461 DOI: 10.5114/pg.2016.57943] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/20/2015] [Accepted: 07/20/2015] [Indexed: 01/01/2023]
Abstract
INTRODUCTION It is generally accepted that mitochondria are a primary source of intracellular reactive oxygen species (ROS). Under physiological circumstances they are permanently formed as by-products of aerobic metabolism in the mitochondria. To counter the harmful effect of ROS, cells possess an antioxidant defence system to detoxify ROS and avert them from accumulation at high concentrations. Mitochondria-located manganese superoxide dismutase (MnSOD, SOD2) successfully converts superoxide to the less reactive hydrogen peroxide (H2O2). To the best of our knowledge, there are no available data regarding immunohistochemical expression of MnSOD in colorectal neoplastic tissues. AIM To investigate the immunohistochemical expression status of MnSOD in colorectal premalignant and malignant lesions. MATERIAL AND METHODS This study was performed on resected specimens obtained from 126 patients who had undergone surgical resection for primary sporadic colorectal cancer, and from 114 patients who had undergone colonoscopy at the Municipal Hospital in Jaworzno (Poland). Paraffin-embedded, 4-µm-thick tissue sections were stained for rabbit polyclonal anti SOD2 antibody obtained from GeneTex (clone TF9-10-H10 from America Diagnostica). RESULTS Results of our study demonstrated that the development of colorectal cancer is connected with increased expression of MnSOD both in adenoma and adenocarcinoma stages. Samples of adenocarcinoma with G2 and G3 grade showed significantly higher levels of immunohistochemical expression of this antioxidant enzyme. Moreover, patients with the presence of lymphovascular invasion and higher degree of regional lymph node status have been also characterised by higher levels of MnSOD expression. The samples of adenoma have been characterised by higher levels of MnSOD expression in comparison to normal mucosa as well. Interestingly, there was no significant correlation between expression and histological type of adenoma. CONCLUSIONS Development of colorectal cancer is connected with increased expression of MnSOD both in adenoma and adenocarcinoma stages.
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Abstract
SIGNIFICANCE Cancer is the second leading cause of death in the United States. Considering the quality of life and treatment cost, the best way to fight against cancer is to prevent or suppress cancer development. Cancer is preventable as indicated by human papilloma virus (HPV) vaccination and tamoxifen/raloxifen treatment in breast cancer prevention. The activities of superoxide dismutases (SODs) are often lowered during early cancer development, making it a rational candidate for cancer prevention. RECENT ADVANCES SOD liposome and mimetics have been shown to be effective in cancer prevention animal models. They've also passed safety tests during early phase clinical trials. Dietary supplement-based SOD cancer prevention provides another opportunity for antioxidant-based cancer prevention. New mechanistic studies have revealed that SOD inhibits not only oncogenic activity, but also subsequent metabolic shifts during early tumorigenesis. CRITICAL ISSUES Lack of sufficient animal model studies targeting specific cancers; and lack of clinical trials and support from pharmaceutical industries also hamper efforts in further advancing SOD-based cancer prevention. FUTURE DIRECTIONS To educate and obtain support from our society that cancer is preventable. To combine SOD-based therapeutics with other cancer preventive agents to obtain synergistic effects. To formulate a dietary supplementation-based antioxidant approach for cancer prevention. Lastly, targeting specific populations who are prone to carcinogens, which can trigger oxidative stress as the mechanism of carcinogenesis.
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Affiliation(s)
- Delira Robbins
- 1 Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital , Memphis, Tennessee
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Piotrowska H, Kucinska M, Murias M. Expression of CYP1A1, CYP1B1 and MnSOD in a panel of human cancer cell lines. Mol Cell Biochem 2013; 383:95-102. [PMID: 23873331 PMCID: PMC3788183 DOI: 10.1007/s11010-013-1758-8] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2013] [Accepted: 07/10/2013] [Indexed: 11/30/2022]
Abstract
The expression of P450 enzymes and antioxidative enzymes in tumour tissue can have a major impact on the responsiveness of tumours to cancer chemotherapeutic drugs, therefore such information may be very precious when experiments are designed. The compressive information, concerning the expression of drug metabolism enzymes or antioxidative enzymes is still lacking, therefore in this study the expression of CYP1A1, CYP1B1 and mitochondrial superoxide dismutase MnSOD (both mRNA and protein) in a panel of eight commonly used cancer cell lines, representing four tumour tissues was assayed. In the study two ovarian cancer cell lines A2780 and SKOV-3, two colorectal cancer LOVO and DLD-1, two breast cancer derived MCF-7 and MDA-MB-231 and two cervical cancer cell lines HeLa and C33A were employed. The relatively high expression of all assayed enzymes was shown in MDA-MB-231 breast cancer cells, lack of cancer cell specific CYP1B1 protein was discovered in LOVO colorectal cells. In order to test possible correlation between expression of CYP1A1, CYP1B1 and MnSOD and modulators of their activity, cytotoxicity of resveratrol and its promising hydroxylated analogue 3,3′,4,4′,5,5′-trans-hexahydroxystilbene against cell lines used in experiment was assayed. The relatively high correlation was found between IC50 values calculated for 3,3′,4,4′,5,5′-trans-hexahydroxystilbene and expression of MnSOD (r = 0.6562).
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Affiliation(s)
- Hanna Piotrowska
- Department of Toxicology, Poznan University of Medical Sciences, ul. Dojazd 30, 60-631, Poznan, Poland
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Schiffman SC, Li Y, Xiao D, Li X, Aiyer HS, Martin RCG. The resistance of esophageal adenocarcinoma to bile salt insult is associated with manganese superoxide dismutase expression. J Surg Res 2010; 171:623-30. [PMID: 20638682 DOI: 10.1016/j.jss.2010.04.038] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2010] [Revised: 03/30/2010] [Accepted: 04/17/2010] [Indexed: 11/30/2022]
Abstract
BACKGROUND Bile acids are implicated as etiologic agents in esophageal cancer. We sought to analyze the impact of bile acid exposure on esophageal epithelial cells, Barrett's metaplastic cells (BE), esophageal adenocarcinoma cells (EAC), and esophageal squamous carcinoma cell (ESC). We sought to determine if cellular resistance is related to manganese superoxide dismutase expression. METHODS Cells were exposed to sodium choleate (CA), sodium deoxycholate (DCA), sodium glycocholate (GCA), sodium taurocholate (TCA), or a 1:1 mixture (MIX) of reagents at concentrations in the range 0.2-0.8 mM. Cell viability was evaluated by MTT assay. Manganese superoxide dismutase (MnSOD) expression was analyzed by Western blot. Statistical analysis was performed using SPSS ver. 17.0, SPSS Inc., Chicago, IL. RESULTS Bile salt exposure inhibited cell viability in esophageal squamous cells in time- and growth-dependent manner. There was a 50% decrease in cell viability from 4 to 24 h. BE, EAC, and ESC cell lines were more resistant to bile insult. In untreated cell lines, MnSOD expression was significantly decreased in EAC and ESC cell lines compared with esophageal squamous epithelial cells and BE cells (P=0.002). Exposure of ESC cells to bile salt increased MnSOD expression. CONCLUSION The confirmation of the role of reactive oxygen species (ROS) and bile acids in esophageal carcinogenesis has interesting implications for chemoprevention in patients with reflux esophagitis and Barrett's esophagus. Further studies are necessary to assess the preventative role of antioxidant supplementation.
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Affiliation(s)
- Suzanne C Schiffman
- Department of Surgery, Division of Surgical Oncology, University of Louisville, Louisville, Kentucky 40202, USA
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Up-regulated manganese superoxide dismutase expression increases apoptosis resistance in human esophageal squamous cell carcinomas. Chin Med J (Engl) 2007. [DOI: 10.1097/00029330-200712010-00006] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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Martin RCG, Ahn J, Nowell SA, Hein DW, Doll MA, Martini BD, Ambrosone CB. Association between manganese superoxide dismutase promoter gene polymorphism and breast cancer survival. Breast Cancer Res 2007; 8:R45. [PMID: 16859522 PMCID: PMC1779484 DOI: 10.1186/bcr1532] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2006] [Revised: 06/13/2006] [Accepted: 07/11/2006] [Indexed: 11/25/2022] Open
Abstract
Background Manganese superoxide dismutase (MnSOD) plays a critical role in the detoxification of mitochondrial reactive oxygen species, constituting a major cellular defense mechanism against agents that induce oxidative stress. A genetic polymorphism in the mitochondrial targeting sequence of this gene has been associated with increased cancer risk and survival in breast cancer. This base pair transition (-9 T > C) leads to a valine to alanine amino acid change in the mitochondrial targeting sequence. A polymorphism has also been identified in the proximal region of the promoter (-102 C>T) that alters the recognition sequence of the AP-2 transcription factor, leading to a reduction in transcriptional activity. The aim of our study was to investigate possible associations of the -102 C>T polymorphism with overall and relapse-free breast cancer survival in a hospital-based case-only study. Materials and methods The relationship between the MnSOD -102 C>T polymorphism and survival was examined in a cohort of 291 women who received chemotherapy and/or radiotherapy for incident breast cancer. The MnSOD -102 C>T genotype was determined using a TaqMan allele discrimination assay. Patient survival was evaluated according to the MnSOD genotype using Kaplan–Meier survival functions. Hazard ratios were calculated from adjusted Cox proportional hazards modeling. All statistical tests were two-sided. Results In an evaluation of all women, there was a borderline significant reduction in recurrence-free survival with either one or both variant alleles (CT + TT) when compared with patients with wild-type alleles (CC) (odds ratio, 0.65; 95% confidence interval, 0.42–1.01). When the analysis was restricted to patients receiving radiation therapy, there was a significant reduction in relapse-free survival in women who were heterozygous for the MnSOD -102 genotype (relative risk, 0.40; 95% confidence interval, 0.18–0.86). Similarly, when the homozygous and heterozygous variant genotypes were combined, there remained a significant reduction in relapse-free survival in this group (hazard ratio, 0.42; 95% confidence interval, 0.20–0.87). Conclusion The MnSOD -102 variant allele appears to be associated with an improved recurrence-free survival in all patients, and more dramatically in subjects who received adjuvant radiation therapy.
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Affiliation(s)
- Robert CG Martin
- Division of Surgical Oncology, Department of Surgery, University of Louisville School of Medicine, Louisville, Kentucky, USA
| | - Jiyoung Ahn
- Nutritional Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, NIH, DHHS, Bethesda, Maryland, USA
- Department of Epidemiology, Roswell Park Cancer Institute, Buffalo, New York, USA
| | - Susan A Nowell
- Division of Molecular Epidemiology, National Center for Toxicological Research, Jefferson, Arkansas, USA
| | - David W Hein
- Department of Pharmacology and Toxicology, and the James Graham Brown Cancer Center, University of Louisville School of Medicine, Louisville, Kentucky, USA
| | - Mark A Doll
- Department of Pharmacology and Toxicology, and the James Graham Brown Cancer Center, University of Louisville School of Medicine, Louisville, Kentucky, USA
| | - Benjamin D Martini
- Department of Pharmacology and Toxicology, and the James Graham Brown Cancer Center, University of Louisville School of Medicine, Louisville, Kentucky, USA
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Wang SH, Wang YZ, Zhang KY, Shen JH, Zhou HQ, Qiu XY. Effect of superoxide dismutase and malondialdehyde metabolic changes on carcinogenesis of gastric carcinoma. World J Gastroenterol 2005; 11:4305-10. [PMID: 16038025 PMCID: PMC4434653 DOI: 10.3748/wjg.v11.i28.4305] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To investigate the relationship between the superoxide dismutase (SOD), malondialdehyde (MDA) metabolic changes and the gastric carcinogenesis.
METHODS: The SOD activity and MDA content were measured in the gastric tissues from the focus center, peripheral and far-end areas of gastric carcinoma (n = 52) and gastric ulcer (n = 10). All the tissues were subjected to routine histological examinations and classifications.
RESULTS: The SOD activity was greatly reduced but the MDA content was markedly increased in the center areas of the non-mucous gastric carcinoma (non-MGC); and the poorly differentiated gastric carcinoma varied. The SOD activity was gradually decreased and the MDA content was gradually increased in the tissues from the focus far-end, peripheral to center areas of non-MGC. Both of the SOD activity and the MDA content were significantly declined and were respectively at same low level in the tissues from the focus center, peripheral, and far-end area with the mucous gastric carcinoma (MGC). In contrast to the gastric ulcer and grade I or II of non-MGC, the same level of the SOD activity and the MDA content were found in the focus center areas. Between non-MGC (groups A-D) and gastric ulcer (group F), the differences of SOD activity and MDA content were very noticeable in the gastric tissues from the focus peripheral and far-end areas, in which the SOD activity showed noticeable increase and the MDA content showed noticeable decrease in the gastric ulcer.
CONCLUSION: The active free radical reaction in the gastric tissues can induce the carcinogenesis of non-MGC. The utmost low ability of antioxidation in the gastric tissues can induce the carcinogenesis of MGC. The metabolic change of the free radicals centralized mostly in the center of ulcerated lesions only, which suggested the ability of antioxidation was declined only in these lesions. However, the metabolism of free radicals varied significantly and the ability of antioxidation declined not only in the local focus area but also in the abroad gastric tissues with gastric carcinoma.
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Affiliation(s)
- Shao-Hong Wang
- Department of Pathology, Central Hospital of Shantou City, Shantou 515031, Guangdong Province, China.
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Martin RCG, Lan Q, Hughes K, Doll MA, Martini BD, Lissowska J, Zatonski W, Rothman N, Hein DW. No apparent association between genetic polymorphisms (-102 C>T) and (-9 T>C) in the human manganese superoxide dismutase gene and gastric cancer(1). J Surg Res 2005; 124:92-7. [PMID: 15734485 DOI: 10.1016/j.jss.2004.09.009] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2004] [Indexed: 01/03/2023]
Abstract
BACKGROUND Manganese superoxide dismutase (MnSOD) plays a critical role in the detoxification of mitochondrial reactive oxygen species, constituting a major cellular defense mechanism against agents that induce oxidative stress. A genetic polymorphism in the mitochondrial targeting sequence of this gene has been associated with increased cancer risk. This one base pair transition (-9 T>C) leads to a Val to Ala amino acid change in the mitochondrial targeting sequence. In addition, the MnSOD promoter contains an activator protein-2 (AP-2) binding site that modifies transcription of MnSOD. Mutations have been identified in the proximal region of the promoter in human tumor cell lines. One of these mutations (-102 C>T) has been shown to change the binding pattern of AP-2, leading to a reduction in transcriptional activity. The aim of our study was to investigate possible associations of the (-9 T>C) and (-102 C>T) polymorphisms with gastric cancer in a population-based case-control study conducted in Warsaw, Poland. MATERIALS AND METHODS DNA was obtained from a population based case-control study of stomach cancer conducted in Warsaw, Poland, between 1994 and 1996. The MnSOD -9 T>C genotype was determined by PCR-RFLP assay. The MnSOD -102 C>T genotype was determined using a TaqMan allele discrimination assay. RESULTS The frequency of the -102 C>T polymorphism was 41% (38/91) in gastric cancer cases and 38% (50/130) in the controls (odds ratio [OR] 1.1, 95% confidence interval [CI] 0.6-2.1). The frequency of the -9 T>C polymorphism was 44% (202/464) in cases and 56% (262/464) in controls (OR 1.1; 95% CI 0.9-1.37). The lack of association was observed in both non-smokers (OR 1.5; 95% CI 0.7-2.34) and smokers (OR 1.1; 95% CI 0.7-1.7). Furthermore, the association was not significant when smokers were segregated by extent of smoking history. CONCLUSION The association of the manganese superoxide dismutase polymorphisms at -102 C>T and the -9 T>C were not found to be associated with gastric cancer in a Polish case-control study.
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Affiliation(s)
- Robert C G Martin
- Department of Surgery, James Graham Brown Cancer Center, University of Louisville School of Medicine, Louisville, Kentucky 40202, USA.
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