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GSTM1 and GSTT1 genes null polymorphisms in kidney cancer susceptibility: evidence based on a meta-analysis

Abstract

Introduction:

Renal cancer is a complex and multifactorial oncourologic disease.

Objective:

To conduct a meta-analysis in order to investigate the association of GSTM1 and GSTT1 genes null polymorphisms in renal cancer.

Method:

Case-control studies in humans, published from 1999 to 2013, that investigated the association of GSTM1 and GSTT1 genes null polymorphisms in renal cancer were grouped in order to make of this meta-analysis.

Results:

Ten articles were selected on the subject proposed. No associations were found between polymorphisms of GSTM1-null (OR = 1.015, 95% CI = 0.897 to 1.147) and GSTT1-null (OR = 1.081, 95% CI = 0.791 to 1.479) and renal cancer.

Conclusions:

Based on the results obtained, we conclude that the GSTM1 and GSTT1 null polymorphisms are not associated with the risk of developing renal cancer, since they have limited role, if there is any on effective contribution in the development of renal tumors.

Keywords:
kidney neoplasms; metaanalysis; polymorphism, genetic

Resumo

Introdução

O câncer renal é uma doença oncourológica complexa e multifatorial.

Objetivo:

Realizar uma meta-análise para investigar a associação do polimorfismo nulo dos genes GSTM1 e GSTT1 no contexto do câncer renal.

Método:

Estudos em seres humanos, do tipo caso-controle, publicados no período de 1999 a 2013, que investigavam a associação do polimorfismo nulo dos genes GSTM1 e GSTT1 no câncer renal, foram agrupados para a confecção da presente meta-análise.

Resultados:

Foram selecionados 10 artigos sobre o tema proposto. Não foram encontradas associações entre o polimorfismo nulo dos genes GSTM1 (OR = 1,015; IC95% = 0,897-1,147) e GSTT1 (OR = 1,081; IC95% = 0,791- 1,479) e o câncer renal.

Conclusões:

Conclui-se que os polimorfismos nulos de GSTM1 e GSTT1 não estão associados ao risco do desenvolvimento de câncer renal, pois apresentam papel limitado, se é que existe alguma contribuição efetiva, no desenvolvimento dos tumores renais.

Palavras-chave:
meta-análise; neoplasias renais; polimorfismo genético

Introduction

Renal cancer is a complex multifactorial urologic disease.11 Banyra O, Tarchynets M, Shulyak A. Renal cell carcinoma: how to hit the targets? Cent European J Urol 2014;66:394-404. It encompasses a series of malignant tumors with genetic polymorphisms affecting the kidneys.22 Linehan WM. Genetic basis of kidney cancer: role of genomics for the development of disease-based therapeutics. Genome Res 2012;22:2089-100. DOI: http://dx.doi.org/10.1101/gr.131110.111
http://dx.doi.org/10.1101/gr.131110.111...
In this context, different types of kidney tumor produce significantly diverse histopathology findings and genetic alterations involving various molecular pathways, in addition to yielding multiple clinical manifestations and treatment options.33 Linehan WM, Ricketts CJ. The metabolic basis of kidney cancer. Semin Cancer Biol 2013;23:46-55. DOI: http://dx.doi.org/10.1016/j.semcancer.2012.06.002
http://dx.doi.org/10.1016/j.semcancer.20...

The incidence of renal cell carcinoma - the most common form of renal cancer - is increasing globally,44 Choueiri TK, Je Y, Cho E. Analgesic use and the risk of kidney cancer: a meta-analysis of epidemiologic studies. Int J Cancer 2014;134:384-96. DOI: http://dx.doi.org/10.1002/ijc.28093
http://dx.doi.org/10.1002/ijc.28093...
and currently ranks third among genitourinary tract tumors.55 Dantas ELR, Lima-Sá FH, Carvalho SMF, Arruda AP, Ribeiro EM, Ribeiro EM. Genética do câncer hereditário. Rev Bras Cancerol 2009;55:263-9. Renal cell carcinoma accounts for approximately three percent of all cases of malignant tumors in adults, with over 270,000 new cases and more than 100,000 deaths a year.66 Zhang J, Guo Z, Bai Y, Cui L, Zhang S, Xu J. Identification of sequence polymorphisms in the displacement loop region of mitochondrial DNA as a risk factor for renal cell carcinoma. Biomed Rep 2013;1:563-6.

7 Behrens G, Leitzmann MF. The association between physical activity and renal cancer: systematic review and meta-analysis. Br J Cancer 2013;108:798-811. PMID: 23412105 DOI: http://dx.doi.org/10.1038/bjc.2013.37
http://dx.doi.org/10.1038/bjc.2013.37...
-88 Ferlay J, Shin HR, Bray F, Forman D, Mathers C, Parkin DM. Estimates of worldwide burden of cancer in 2008: GLOBOCAN 2008. Int J Cancer 2010;127:2893-917. PMID: 21351269 DOI: http://dx.doi.org/10.1002/ijc.25516
http://dx.doi.org/10.1002/ijc.25516...

The risk factors for the development of renal cancer include smoking, obesity, hypertension, diabetes mellitus type 277 Behrens G, Leitzmann MF. The association between physical activity and renal cancer: systematic review and meta-analysis. Br J Cancer 2013;108:798-811. PMID: 23412105 DOI: http://dx.doi.org/10.1038/bjc.2013.37
http://dx.doi.org/10.1038/bjc.2013.37...
and genetic factors.99 Audenet F, Yates DR, Cancel-Tassin G, Cussenot O, Rouprêt M. Genetic pathways involved in carcinogenesis of clear cell renal cell carcinoma: genomics towards personalized medicine. BJU Int 2012;109:1864-70. PMID: 22035299 DOI: http://dx.doi.org/10.1111/j.1464-410X.2011.10661.x
http://dx.doi.org/10.1111/j.1464-410X.20...
In the last decades, the genes in charge of coding hepatic xenobiotic metabolizing enzymes such as glutathione S-transferases (GST) have gained prominence in oncogenetics. Genetic polymorphisms in GST have also earned a special place in cancer research, including renal cell carcinoma.1010 Yang X, Long S, Deng J, Deng T, Gong Z, Hao P. Glutathione S-transferase polymorphisms (GSTM1, GSTT1 and GSTP1) and their susceptibility to renal cell carcinoma: an evidence-based meta-analysis. PLoS One 2013;8:e63827. DOI: http://dx.doi.org/10.1371/journal.pone.0063827
http://dx.doi.org/10.1371/journal.pone.0...

Human GST can be divided into two distinct superfamilies, linked to microsomal and cytosolic proteins. Cytosolic GSTs are subject to genetic polymorphisms in human populations. Human genes are divided into six classes, two of which are the Mu class, present in the GSTM1 gene on chromosome 1p13.3, and the Theta class, found in the GSTT1 gene in chromosome 22q11.23.1111 Tew KD, Manevich Y, Grek C, Xiong Y, Uys J, Townsend DM. The role of glutathione S-transferase P in signaling pathways and S-glutathionylation in cancer. Free Radic Biol Med 2011;51:299-313. PMID: 21558000 DOI: http://dx.doi.org/10.1016/j.freeradbiomed.2011.04.013
http://dx.doi.org/10.1016/j.freeradbiome...

Genetic polymorphisms categorized as null result from genetic deletions. In this context, the following allelic possibilities may be observed: (1) homozygous dominant subjects with two functional alleles (GST+/GST+), (2) heterozygous individuals with only one functional allele (GST+/GST-), or (3) homozygous recessive individuals without functional alleles (GST-/GST-).1212 Luo W, Kinsey M, Schiff JD, Lessnick SL. Gluthatione S-transferases in pediatric cancer. Front Oncol 2011;1:39. DOI: http://dx.doi.org/10.3389/fonc.2011.00039
http://dx.doi.org/10.3389/fonc.2011.0003...
Thus, homozygous recessive individuals with a GST null genotype are not capable of producing the GST protein variant affected by the deletion, which usually places them at risk for the development of many types of cancer, particularly when exposed to carcinogenic substances.1010 Yang X, Long S, Deng J, Deng T, Gong Z, Hao P. Glutathione S-transferase polymorphisms (GSTM1, GSTT1 and GSTP1) and their susceptibility to renal cell carcinoma: an evidence-based meta-analysis. PLoS One 2013;8:e63827. DOI: http://dx.doi.org/10.1371/journal.pone.0063827
http://dx.doi.org/10.1371/journal.pone.0...

GSTM1 and GSTT1 null polymorphisms have been the subject of several case-control studies on renal cell carcinoma.1010 Yang X, Long S, Deng J, Deng T, Gong Z, Hao P. Glutathione S-transferase polymorphisms (GSTM1, GSTT1 and GSTP1) and their susceptibility to renal cell carcinoma: an evidence-based meta-analysis. PLoS One 2013;8:e63827. DOI: http://dx.doi.org/10.1371/journal.pone.0063827
http://dx.doi.org/10.1371/journal.pone.0...
Interestingly, the conclusions reported in these studies varied significantly, with some authors describing absence and others presence of associations between GSTM1 and GSTT1 null polymorphisms and kidney cancer. This generalized lack of agreement motivated the organization of the present study, a meta-analysis designed to investigate the association between GSTM1 and GSTT1 null polymorphisms and kidney cancer.

Method

This study is a meta-analysis. The purpose of a meta-analysis is to examine the combined outcomes of several studies on the same topic.1313 Conn VS, Ruppar TM, Phillips LJ, Chase JA. Using meta-analyses for comparative effectiveness research. Nurs Outlook 2012;60:182-90. DOI: http://dx.doi.org/10.1016/j.outlook.2012.04.004
http://dx.doi.org/10.1016/j.outlook.2012...
This type of study is widely used in medical sciences, once the aggregation of the data derived from numerous studies on the same subject increases the level of confidence of the ensuing statistical inferences.1414 Langfelder P, Mischel PS, Horvath S. When is hub gene selection better than standard meta-analysis? PLoS One 2013;8:e61505. DOI: http://dx.doi.org/10.1371/journal.pone.0061505
http://dx.doi.org/10.1371/journal.pone.0...
A meta-analysis may be carried out to underline the agreement existing between studies on a particular topic, or to stress disagreements between studies, thus indicating the need for further joint analysis to strengthen the existing conclusions on the matter at hand.1515 Jackson D, Riley R, White IR. Multivariate meta-analysis: potential and promise. Stat Med 2011;30:2481-98. DOI: http://dx.doi.org/10.1002/sim.4247
http://dx.doi.org/10.1002/sim.4247...
The main steps of a meta-analysis are: (1) bibliographic search, (2) processing the outcomes of each selected study into a common indicator, (3) assessing the homogeneity of the outcomes, (4) modeling the variation between studies, and (5) assessing sensitivity.1616 Greco T, Zangrillo A, Biondi-Zoccai G, Landoni G. Meta-analysis: pitfalls and hints. Heart Lung Vessel 2013;5:219-25.

Relevant human studies published between 1999 and 2013 were identified in the SciELO database (Scientific Electronic Library Online) and on the NCBI (National Center for Biotechnology Information, USA) PubMed. The search for papers included combinations of keywords "polymorphism," "GSTM1 and GSTT1 genes," and "kidney or renal cancer." Ten papers on GSTM1 and GSTT1 null polymorphisms and kidney cancer were included in the meta-analysis.

In a meta-analysis, it is important to assess the heterogeneity of the included studies. Design and method differences may pose significant challenges to the aggregation of study results.1717 Gasparrini A, Armstrong B, Kenwarda MG. Multivariate meta-analysis for non-linear and other multi-parameter associations. Stat Med 2012;31:3821-39. DOI: http://dx.doi.org/10.1002/sim.5471
http://dx.doi.org/10.1002/sim.5471...
Heterogeneity may be typified into three categories: clinical, methodological, and statistical. In order to minimize the impact of these parameters, inclusion and exclusion criteria are broadly defined.1818 Berwanger O, Suzumura EA, Buehler AM, Oliveira JB. Como avaliar criticamente revisões sistemáticas e metanálises? Rev Bras Ter Intensiva 2007;19:475-80. The papers included in the present study had to meet the following inclusion/exclusion criteria: case-control studies enrolling humans published between 1999 and 2013 on the association between GSTM1 and GSTT1 null polymorphisms and kidney cancer. The following data were collected: site of the study; first author's name; year of publication of the paper; total number of cases and controls; and genotypic frequency of GSTM1 and GSTT1 null polymorphisms. The studies included in this meta-analysis looked into patients with histologically confirmed renal cell carcinoma and polymorphisms detected with PCR.

Heterogeneity - defined as the diversity between studies - may significantly affect the results. Diversity can be assessed using the χ22 Linehan WM. Genetic basis of kidney cancer: role of genomics for the development of disease-based therapeutics. Genome Res 2012;22:2089-100. DOI: http://dx.doi.org/10.1101/gr.131110.111
http://dx.doi.org/10.1101/gr.131110.111...
test for heterogeneity.1313 Conn VS, Ruppar TM, Phillips LJ, Chase JA. Using meta-analyses for comparative effectiveness research. Nurs Outlook 2012;60:182-90. DOI: http://dx.doi.org/10.1016/j.outlook.2012.04.004
http://dx.doi.org/10.1016/j.outlook.2012...
The genotype frequencies reported in the papers included in this meta-analysis were grouped in a single table and diversity was assessed with the χ22 Linehan WM. Genetic basis of kidney cancer: role of genomics for the development of disease-based therapeutics. Genome Res 2012;22:2089-100. DOI: http://dx.doi.org/10.1101/gr.131110.111
http://dx.doi.org/10.1101/gr.131110.111...
test for heterogeneity in 2x2 contingency tables, to compare between the different odds ratios (OR) with a 95% confidence interval described in each study.1616 Greco T, Zangrillo A, Biondi-Zoccai G, Landoni G. Meta-analysis: pitfalls and hints. Heart Lung Vessel 2013;5:219-25.

The null hypothesis was confirmed for p-values > 0.05, i.e., the compared studies were homogeneous. In such case, a fixed-effect model is used, in which the studies are assumed to point in the same direction.1919 Higgins JP, White IR, Wood AM. Imputation methods for missing outcome data in meta-analysis of clinical trials. Clin Trials 2008;5:225-39. DOI: http://dx.doi.org/10.1177/1740774508091600
http://dx.doi.org/10.1177/17407745080916...
In this context, the Mantel-Haenszel test is the most commonly used method.2020 Ayres M, Ayres Jr. M, Ayres DL, Santos AAS. BioEstat: aplicações estatísticas nas áreas das Ciências Biomédicas. Belém: Sociedade Civil Mamirauá; 2007. p.132-214. On the other hand, if the χ22 Linehan WM. Genetic basis of kidney cancer: role of genomics for the development of disease-based therapeutics. Genome Res 2012;22:2089-100. DOI: http://dx.doi.org/10.1101/gr.131110.111
http://dx.doi.org/10.1101/gr.131110.111...
test for heterogeneity yields a p-value < 0.05, the compared studies are diverse and heterogeneous. In this scenario, random effect methods2121 Zhang Y, Liu T, Meyer CA, Eeckhoute J, Johnson DS, Bernstein BE, Nusbaum C, et al. Model-based analysis of ChIP-Seq (MACS). Genome Biol 2008;9:R137. DOI: http://dx.doi.org/10.1186/gb-2008-9-9-r137
http://dx.doi.org/10.1186/gb-2008-9-9-r1...
such as the DerSimonian Laird estimator 1515 Jackson D, Riley R, White IR. Multivariate meta-analysis: potential and promise. Stat Med 2011;30:2481-98. DOI: http://dx.doi.org/10.1002/sim.4247
http://dx.doi.org/10.1002/sim.4247...
,2222 Higgins JP, Whitehead A, Simmonds M. Sequential methods for random-effects meta-analysis. Stat Med 2011;30:903-21. DOI: http://dx.doi.org/10.1002/sim.4088
http://dx.doi.org/10.1002/sim.4088...
are recommended.

Global association tests were then used to assess the significance of the correlation between GSTM1 and GSTT1 null polymorphisms and kidney cancer in the included studies combined. The impact these polymorphisms in the development of renal cell carcinoma was assessed using a fixed-effect model for gene GSTM1 (p = 0.678) and a random-effect model for gene GSTT1 (p = 0.0002) using software package BioEstat® 5.0.2020 Ayres M, Ayres Jr. M, Ayres DL, Santos AAS. BioEstat: aplicações estatísticas nas áreas das Ciências Biomédicas. Belém: Sociedade Civil Mamirauá; 2007. p.132-214.

Odds ratios, 95% confidence intervals, and the weights attributed to each study individually and combined for both fixed-effect and random-effect models were calculated to estimate the global impact of the polymorphisms. Studies with greater statistical power, i.e., with larger enrolled populations and greater intervention effects, were given greater weights.1818 Berwanger O, Suzumura EA, Buehler AM, Oliveira JB. Como avaliar criticamente revisões sistemáticas e metanálises? Rev Bras Ter Intensiva 2007;19:475-80. These tests yield forest plots, which allow the summarization of all the information on the effect and contribution of each study to the analysis.1313 Conn VS, Ruppar TM, Phillips LJ, Chase JA. Using meta-analyses for comparative effectiveness research. Nurs Outlook 2012;60:182-90. DOI: http://dx.doi.org/10.1016/j.outlook.2012.04.004
http://dx.doi.org/10.1016/j.outlook.2012...

Results

This meta-analysis included ten papers on the association between GSTM1 and GSTT1 null polymorphisms and kidney cancer, published between 1999 and 2013. Five papers were excluded for not containing control groups.2323 Gattás GJ, Kato M, Soares-Vieira JA, Siraque MS, Kohler P, Gomes L, et al. Ethnicity and glutathione S-transferase (GSTM1/GSTT1) polymorphisms in a Brazilian population. Braz J Med Biol Res 2004;37:451-8. DOI: http://dx.doi.org/10.1590/S0100-879X2004000400002
http://dx.doi.org/10.1590/S0100-879X2004...

24 Chow WH, Dong LM, Devesa SS. Epidemiology and risk factors for kidney cancer. Nat Rev Urol 2010;7:245-57. DOI: http://dx.doi.org/10.1038/nrurol.2010.46
http://dx.doi.org/10.1038/nrurol.2010.46...

25 Moore LE, Boffetta P, Karami S, Brennan P, Stewart PS, Hung R, et al. Occupational trichloroethylene exposure and renal carcinoma risk: evidence of genetic susceptibility by reductive metabolism gene variants. Cancer Res 2010;70:6527-36. PMID: 20663906 DOI: http://dx.doi.org/10.1158/0008-5472.CAN-09-4167
http://dx.doi.org/10.1158/0008-5472.CAN-...
-2626 Deenen MJ, Cats A, Beijnen JH, Schelles JH. Part 3: Pharmacogenetic variability in phase II anticancer drug metabolism. Oncologist 2011;16:992-1005. DOI: http://dx.doi.org/10.1634/theoncologist.2010-0260
http://dx.doi.org/10.1634/theoncologist....
Only studies meeting the inclusion and exclusion criteria were considered (Figure 1).2727 Longuemaux S, Deloménie C, Gallou C, Méjean A, Vincent-Viry M, Bouvier R, et al. Candidate genetic modifiers of individual susceptibility to renal cell carcinoma: a study of polymorphic human xenobiotic-metabolizing enzymes. Cancer Res 1999;59:2903-8.

28 Sweeney C, Farrow DC, Schwartz SM, Eaton DL, Checkoway H, Vaughan TL. Glutathione S-transferase M1, T1, and P1 polymorphisms as risk factors for renal cell carcinoma: a case-control study. Cancer Epidemiol Biomarkers Prev 2000;9:449-54.

29 Buzio L, De Palma G, Mozzoni P, Tondel M, Buzio C, Franchini I, et al. Glutathione S-transferases M1-1 and T1-1 as risk modifiers for renal cell cancer associated with occupational exposure to chemicals. Occup Environ Med 2003;60:789-93. PMID: 14504370 DOI: http://dx.doi.org/10.1136/oem.60.10.789
http://dx.doi.org/10.1136/oem.60.10.789...

30 Wiesenhütter B, Selinski S, Golka K, Brüning T, Bolt HM. Re-assessment of the influence of polymorphisms of phase-II metabolic enzymes on renal cell cancer risk of trichloroethylene-exposed workers. Int Arch Occup Environ Health 2007;81:247-51. PMID: 17479278 DOI: http://dx.doi.org/10.1007/s00420-007-0200-5
http://dx.doi.org/10.1007/s00420-007-020...

31 Karami S, Boffetta P, Rothman N, Hung RJ, Stewart T, Zaridze D, et al. Renal cell carcinoma, occupational pesticide exposure and modification by glutathione S-transferase polymorphisms. Carcinogenesis 2008;29:1567-71. DOI: http://dx.doi.org/10.1093/carcin/bgn153
http://dx.doi.org/10.1093/carcin/bgn153...

32 Ćorić V, Plješa-Ercegovac M, Matić M, Krivić B, Šuvakov S, Tulić C, et al. The role of GSTM1 and GSTT1 polymorphism in patients with renal cell carcinoma. J Med Biochem 2010;29:204-10.

33 De Martino M, Klatte T, Schatzl G, Remzi M, Waldert M, Haitel A, et al. Renal cell carcinoma Fuhrman grade and histological subtype correlate with complete polymorphic deletion of glutathione S-transferase M1 gene. J Urol 2010;183:878-83. DOI: http://dx.doi.org/10.1016/j.juro.2009.11.032
http://dx.doi.org/10.1016/j.juro.2009.11...

34 Salinas-Sánchez AS, Sánchez-Sánchez F, Donate-Moreno MJ, Rubio-del-Campo A, Serrano-Oviedo L, Gimenez-Bachs JM, et al. GSTT1, GSTM1, and CYP1B1 gene polymorphisms and susceptibility to sporadic renal cell cancer. Urol Oncol 2012;30:864-70. DOI: http://dx.doi.org/10.1016/j.urolonc.2010.10.001
http://dx.doi.org/10.1016/j.urolonc.2010...

35 Ahmad ST, Arjumand W, Seth A, Kumar Saini A, Sultana S. Impact of glutathione transferase M1, T1, and P1 gene polymorphisms in the genetic susceptibility of North Indian population to renal cell carcinoma. DNA Cell Biol 2012;31:636-43. DOI: http://dx.doi.org/10.1089/dna.2011.1392
http://dx.doi.org/10.1089/dna.2011.1392...
-3636 Farouk H, Kandil D, Kamel S, Elghoroury EA, Elshamaa MF, Sabry S, et al. Effect of GSTM1 and GSTT1 deletions in the development of oxidative stress in children with chronic kidney disease. J Clin Basic Cardiol 2013;16:1-5.

Figure 1
Criteria for the identification, inclusion, and exclusion of studies in the meta-analysis.

A total of 9,188 genotyping tests for GSTM1 and GSTT1 null polymorphisms were carried out. Tests for GSTM1 polymorphisms were performed in 4,595 individuals, 1,717 (37.4%) diagnosed with kidney cancer (cases) and 2,878 (62.6%) healthy subjects (controls).

Tests for GSTT1 polymorphisms were performed in 4,593 individuals, 1,720 (37.4%) with kidney cancer and 2,873 (62.6%) healthy subjects. Gene GSTM1 was found in 857 (49.9%) and not found in 860 (50.1%) individuals diagnosed with cancer; 1,279 (74.4%) patients were positive and 441 (25.6%) were negative for gene GSTT1.

Among controls, 1,442 (50.1%) individuals were positive and 1,436 (49.9%) negative for gene GSTM1, while 2,031 (70.7%) were positive and 842 (29.3%) were negative for gene GSTT1. Data on GSTM1 and GSTT1 genotyping tests are shown in Tables 1 and 2, respectively.

Table 1
Analysis of GST M1 null polymorphism in cases and controls, papers published between 1999 and 2013
Table 2
Analysis of GSTT1 null polymorphism in cases and controls, papers published between 1999 and 2013

The group of patients with renal cancer ranged from 44 with both genes3636 Farouk H, Kandil D, Kamel S, Elghoroury EA, Elshamaa MF, Sabry S, et al. Effect of GSTM1 and GSTT1 deletions in the development of oxidative stress in children with chronic kidney disease. J Clin Basic Cardiol 2013;16:1-5. to 624 individuals with gene GSTM1 and 628 with gene GSTT1.3131 Karami S, Boffetta P, Rothman N, Hung RJ, Stewart T, Zaridze D, et al. Renal cell carcinoma, occupational pesticide exposure and modification by glutathione S-transferase polymorphisms. Carcinogenesis 2008;29:1567-71. DOI: http://dx.doi.org/10.1093/carcin/bgn153
http://dx.doi.org/10.1093/carcin/bgn153...

The control group ranged from 14 individuals with both genes3636 Farouk H, Kandil D, Kamel S, Elghoroury EA, Elshamaa MF, Sabry S, et al. Effect of GSTM1 and GSTT1 deletions in the development of oxidative stress in children with chronic kidney disease. J Clin Basic Cardiol 2013;16:1-5. to 887 with gene GSTM1 and 913 with gene GSTT1.3131 Karami S, Boffetta P, Rothman N, Hung RJ, Stewart T, Zaridze D, et al. Renal cell carcinoma, occupational pesticide exposure and modification by glutathione S-transferase polymorphisms. Carcinogenesis 2008;29:1567-71. DOI: http://dx.doi.org/10.1093/carcin/bgn153
http://dx.doi.org/10.1093/carcin/bgn153...

No associations were found between GSTM1 (OR = 1.015; 95% CI 0.897-1.147) and GSTT1 (OR = 1.081; 95% CI 0.791-1.479) null polymorphisms and kidney cancer.

In the forest plots generated in the meta-analysis, each line represented a different study. The rhombus at the bottom of the diagram represented the combination of results of the studies included in the metaanalysis. The result of each study is given in graphic and numerical form. In the graphic representations, the central squares account for relative risk (RR) or hazard ratios, while the lines account for confidence intervals (CI). When the CI does not cross the null line (position 1.0 in the graph), the study is deemed statistically significant, either separately or combined. The larger the sample considered in the study, the narrower the confidence intervals and the greater the areas of the squares, denoting more accurate results and greater contribution to the meta-analysis.1818 Berwanger O, Suzumura EA, Buehler AM, Oliveira JB. Como avaliar criticamente revisões sistemáticas e metanálises? Rev Bras Ter Intensiva 2007;19:475-80. Two graphs were generated, one for gene GSTM1 (Figure 2) and another for gene GSTT1 (Figure 3).

Figure 2
Odds ratios (OR) and 95% confidence interval (95% CI) with lower and upper limits, for GSTM1 null polymorphism in all studies with non-significant chi-square test for heterogeneity (Mantel- Haenszel test).
Figure 3
Odds ratios (OR) and 95% confidence interval (95% CI) with lower and upper limits, for GSTT1 null polymorphism in all studies with significant chi-square test for heterogeneity (DerSimonian-Laird estimator).

Discussion

Mixed results were reported in the studies on GSTM1 and GSTT1 null polymorphisms in patients with various tumor types. Lack of a correlation with polymorphisms was reported in cases of lung cancer3737 López-Cima MF, Alvarez-Avellón SM, Pascual T, Fernández-Somoano A, Tardón A. Genetic polymorphisms in CYP1A1, GSTM1, GSTP1 and GSTT1 metabolic genes and risk of lung cancer in Asturias. BMC Cancer 2012;12:433. DOI: http://dx.doi.org/10.1186/1471-2407-12-433
http://dx.doi.org/10.1186/1471-2407-12-4...
and renal cell carcinoma.2424 Chow WH, Dong LM, Devesa SS. Epidemiology and risk factors for kidney cancer. Nat Rev Urol 2010;7:245-57. DOI: http://dx.doi.org/10.1038/nrurol.2010.46
http://dx.doi.org/10.1038/nrurol.2010.46...

25 Moore LE, Boffetta P, Karami S, Brennan P, Stewart PS, Hung R, et al. Occupational trichloroethylene exposure and renal carcinoma risk: evidence of genetic susceptibility by reductive metabolism gene variants. Cancer Res 2010;70:6527-36. PMID: 20663906 DOI: http://dx.doi.org/10.1158/0008-5472.CAN-09-4167
http://dx.doi.org/10.1158/0008-5472.CAN-...
-2626 Deenen MJ, Cats A, Beijnen JH, Schelles JH. Part 3: Pharmacogenetic variability in phase II anticancer drug metabolism. Oncologist 2011;16:992-1005. DOI: http://dx.doi.org/10.1634/theoncologist.2010-0260
http://dx.doi.org/10.1634/theoncologist....
,2929 Buzio L, De Palma G, Mozzoni P, Tondel M, Buzio C, Franchini I, et al. Glutathione S-transferases M1-1 and T1-1 as risk modifiers for renal cell cancer associated with occupational exposure to chemicals. Occup Environ Med 2003;60:789-93. PMID: 14504370 DOI: http://dx.doi.org/10.1136/oem.60.10.789
http://dx.doi.org/10.1136/oem.60.10.789...
,3838 Huang JX, Li FY, Xiao W, Song ZX, Qian RY, Chen P, et al. Expression of thymidylate synthase and glutathione-s-transferase pi in patients with esophageal squamous cell carcinoma. World J Gastroenterol 2009;15:4316-21. DOI: http://dx.doi.org/10.3748/wjg.15.4316
http://dx.doi.org/10.3748/wjg.15.4316...
Other authors suggested the existence of associations with one or both polymorphisms in cases of head and neck tumors,3939 Zhang Y, Ni Y, Zhang H, Pan Y, Ma J, Wang L. Association between GSTM1 and GSTT1 allelic variants and head and neck squamous cell cancinoma. PLoS One 2012;7:e47579. DOI: http://dx.doi.org/10.1371/journal.pone.0047579
http://dx.doi.org/10.1371/journal.pone.0...
prostate cancer,4040 Gong M, Dong W, Shi Z, Xu Y, Ni W, An R. Genetic polymorphisms of GSTM1, GSTT1, and GSTP1 with prostate cancer risk: a meta-analysis of 57 studies. PLoS One 2012;7:e50587. DOI: http://dx.doi.org/10.1371/journal.pone.0050587
http://dx.doi.org/10.1371/journal.pone.0...
breast cancer,4141 Duggan C, Ballard-Barbash R, Baumgartner RN, Baumgartner KB, Bernstein L, McTiernan A. Associations between null mutations in GSTT1 and GSTM1, the GSTP1 Ile(105)Val polymorphism, and mortality in breast cancer survivors. Springerplus 2013;2:450. DOI: http://dx.doi.org/10.1186/2193-1801-2-450
http://dx.doi.org/10.1186/2193-1801-2-45...
cervical cancer,4242 Gao LB, Pan XM, Li LJ, Liang WB, Bai P, Rao L, et al. Null genotypes of GSTM1 and GSTT1 contribute to risk of cervical neoplasia: an evidence-based meta-analysis. PLoS One 2011;6:e20157. DOI: http://dx.doi.org/10.1371/journal.pone.0020157
http://dx.doi.org/10.1371/journal.pone.0...
and hepatocellular carcinoma.4343 Liu K, Zhang L, Lin X, Chen L, Shi H, Magaye R, et al. Association of GST genetic polymorphisms with the susceptibility to hepatocellular carcinoma (HCC) in Chinese population evaluated by an updated systematic meta-analysis. PLoS One 2013;8:e57043. DOI: http://dx.doi.org/10.1371/journal.pone.0057043
http://dx.doi.org/10.1371/journal.pone.0...

Several meta-analyses have looked into the involvement of GSTM1 and GSTT1 null polymorphisms in various tumor types.

Gong et al.4040 Gong M, Dong W, Shi Z, Xu Y, Ni W, An R. Genetic polymorphisms of GSTM1, GSTT1, and GSTP1 with prostate cancer risk: a meta-analysis of 57 studies. PLoS One 2012;7:e50587. DOI: http://dx.doi.org/10.1371/journal.pone.0050587
http://dx.doi.org/10.1371/journal.pone.0...
published a meta-analysis investigating the association between GSTM1 and GSTT1 null polymorphisms and prostate cancer and concluded that individuals with a GSTM1-null genotype or null genotypes for both genes were at higher risk of developing prostate cancer. On the other hand, the GSTT1-null genotype alone was not significantly associated with onset of prostate cancer. Liu et al.,4444 Liu D, Liu Y, Ran L, Shang H, Li D. GSTT1 and GSTM1 polymorphisms and prostate cancer risk in Asians: a systematic review and meta-analysis. Tumour Biol 2013;34:2539-44. DOI: http://dx.doi.org/10.1007/s13277-013-0778-z
http://dx.doi.org/10.1007/s13277-013-077...
in another metaanalysis, reached similar conclusions.

The authors of another meta-analysis4242 Gao LB, Pan XM, Li LJ, Liang WB, Bai P, Rao L, et al. Null genotypes of GSTM1 and GSTT1 contribute to risk of cervical neoplasia: an evidence-based meta-analysis. PLoS One 2011;6:e20157. DOI: http://dx.doi.org/10.1371/journal.pone.0020157
http://dx.doi.org/10.1371/journal.pone.0...
assessed GSTM1 and GSTT1 null polymorphisms in cases of cervical cancer and concluded that null genotypes alone or together were associated with significantly increased risk of developing the disease. The same study also evaluated two interactions between the genes and environmental factors such as smoking and HPV infection, but the authors did not find associations between the analyzed polymorphisms and environmental factors.

A more recent meta-analysis4343 Liu K, Zhang L, Lin X, Chen L, Shi H, Magaye R, et al. Association of GST genetic polymorphisms with the susceptibility to hepatocellular carcinoma (HCC) in Chinese population evaluated by an updated systematic meta-analysis. PLoS One 2013;8:e57043. DOI: http://dx.doi.org/10.1371/journal.pone.0057043
http://dx.doi.org/10.1371/journal.pone.0...
including studies performed with Chinese populations investigated the association between susceptibility to hepatocellular carcinoma and GST null polymorphisms. The authors suggested that Chinese populations with GSTM1 and GSTT1 null polymorphisms were at higher risk of developing hepatocellular carcinoma.

A meta-analysis by Tang et al.4545 Tang Q, Li J, Zhang S, Yuan B, Sun H, Wu D, et al. GSTM1 and GSTT1 null polymorphisms and childhood acute leukemia risk: evidence from 26 case-control studies. PLoS One 2013;8:e78810. DOI: http://dx.doi.org/10.1371/journal.pone.0078810
http://dx.doi.org/10.1371/journal.pone.0...
looked into the impact of null polymorphisms of the main GSTs in the development of acute leukemia in children. The authors associated GSTM1 null polymorphism with increased risk of developing pediatric acute leukemia, although an equal association was not reported for GSTT1-null genotypes.

In a meta-analysis similar to ours, Yang et al.1010 Yang X, Long S, Deng J, Deng T, Gong Z, Hao P. Glutathione S-transferase polymorphisms (GSTM1, GSTT1 and GSTP1) and their susceptibility to renal cell carcinoma: an evidence-based meta-analysis. PLoS One 2013;8:e63827. DOI: http://dx.doi.org/10.1371/journal.pone.0063827
http://dx.doi.org/10.1371/journal.pone.0...
reviewed cases of null polymorphism in three GST genes: GSTM1, GSTT1, and GSTP1. The conclusions the authors reported were similar to the ones described in this metaanalysis, i.e., no association was found between null polymorphisms in these three genes and risk of developing renal cell carcinoma. Another meta-analysis on the same topic failed to find associations with isolated polymorphisms, but the analysis of the interaction between GSTM1 and GSTT1 revealed significant associations between the double-null genotype and renal cancer.4646 Jia CY, Liu YJ, Cong XL, Ma YS, Sun R, Fu D, et al. Association of glutathione S-transferase M1, T1, and P1 polymorphisms with renal cell carcinoma: evidence from 11 studies. Tumour Biol 2014;35:3867-73. DOI: http://dx.doi.org/10.1007/s13277-013-1513-5
http://dx.doi.org/10.1007/s13277-013-151...
A meta-analysis by Liu et al.4747 Liu R, Wang H, Liu L, Zhou Q. No association between the GSTM1 null genotype and risk of renal cell carcinoma: a meta-analysis. Asian Pac J Cancer Prev. 2013;13:3109-12. DOI: http://dx.doi.org/10.7314/APJCP.2012.13.7.3109
http://dx.doi.org/10.7314/APJCP.2012.13....
found no associations between GSTM1 null polymorphism and renal cancer.

In general terms, meta-analyses face important limitations as they attempt to group studies carried out in different places, at different times, using different methods. The number of studies pooled for the purposes of a meta-analysis may also be a relevant limitation. A meta-analysis with a greater number of studies is likely to yield more reliable results and conclusions. In contrast, when few studies are compiled for analysis, a roster of issues such as poor ethnic representation and lack of relevant oncologic variables - environmental exposure, patient habits etc. - may also arise.

Conclusion

The results of this meta-analysis suggest that GSTM1 and GSTT1 null polymorphisms are not associated with risk of developing kidney cancer. The polymorphisms analyzed in this study appear to have a limited role, if any, in the development of renal tumors. Considering the significant increase in the number of studies on the topic and the growing knowledge on variables relevant to renal cancer care, other meta-analyses should be organized to strengthen the pool of statistical data and address discordant findings.

Acknowledgement

The authors would like to thank the Department of Medicine of the Pontifical Catholic University of Goiás (PUC-Goiás), Professor Fábia Maria Oliveira Pinho, PhD, coordinator of program completion studies, and Professor Marcus Vinícius Paiva de Oliveira for their invaluable help.

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Publication Dates

  • Publication in this collection
    Apr-Jun 2015

History

  • Received
    26 June 2014
  • Accepted
    12 Nov 2014
Sociedade Brasileira de Nefrologia Rua Machado Bittencourt, 205 - 5ºandar - conj. 53 - Vila Clementino - CEP:04044-000 - São Paulo SP, Telefones: (11) 5579-1242/5579-6937, Fax (11) 5573-6000 - São Paulo - SP - Brazil
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