Abstract
Glutathione peroxidase (GPX), one of the antioxidant enzymes, exerts a vital role in reducing oxidative damage. GPX1 Pro198Leu (rs1050450) polymorphism has been reported in the development of several cancers, while the results were inconsistent. We thus conducted this meta-analysis to identify the association between GPX1 (rs1050450) polymorphism and cancer risk. 52 eligible publications with 60 case-control studies were included, with 21,296 cancer patients and 30,346 controls. The results in total population suggested there was a significant association between GPX1 (rs1050450) polymorphism and cancer susceptibility in part genetic models (TT vs CT+CC: OR = 1.15, 95% CI = 1.01-1.32, P = 0.042; TT vs CC: OR = 1.15, 95% CI = 1.00-1.31, P = 0.044; T vs C: OR = 1.09, 95% CI = 1.01-1.17, P = 0.02). The stratified analysis by cancer types suggested a positive correlation between GPX1 (rs1050450) polymorphism and the development of bladder cancer (TT+CT vs CC: OR = 1.72, 95% CI = 1.09-2.70, P = 0.019; TT vs CT+CC: OR = 3.56, 95% CI = 1.42-8.94, P = 0.007; TT vs CC: OR = 3.75, 95% CI = 1.41-9.94, P = 0.008; T vs C: OR = 1.941, 95% CI = 1.17-3.22, P = 0.01) as well as head and neck cancer (TT vs CT+CC: OR = 2.19, 95% CI = 1.39-3.46, P = 0.001) and brain cancer (TT+CT vs CC: OR = 1.19, 95% CI = 1.03-1.37, P = 0.018). These results support that GPX1 (rs1050450) polymorphism might be a candidate marker for cancer risk with type-specific effects.
Keywords: Glutathione peroxidase-1, rs1050450, polymorphism, cancer, susceptibility
Introduction
Cancer is an increasingly leading cause of death and is considered as a severe health burden in both developing and developed countries [1]. A variety of underlying mechanisms have been confirmed to demonstrate the carcinogenesis process and imbalance of oxidative stress [2]. Oxidation has been proved to participate in quite a few pathogenic processes, including anti-infection process, aging, carcinogenesis, metastasis and angiogenesis [3].
During these processes, previous evidence has demonstrated that reactive oxygen species (ROS)-mediated oxidative damage played a critical role, which initiated a storm of free radical cascade and subsequently caused indirect damage to cellular component, leading to denaturing and dysfunction of proteins [4], saturation and structural modification of certain lipids and DNA strains breaking [5]. Because most of these damages were irreversible and fatal, oxidative stress might decrease the genome stability and thus increase the possibility of tumorgenesis.
Anti-oxidative system plays a key role in preventing catastrophic oxidative storm in our body and it works as a balanced cycle. With the consumption of reductive species, certain enzyme families recycle to restore these reductive active molecules. Glutathione peroxidase (GPX) family is one of those anti-oxidative enzyme families, among which GPX1, encoded by GPX1 gene in humans and locating on chromosome 3, is the most abundant one functioning in the detoxification of hydrogen peroxide [6].
Multiple single nucleotide polymorphisms (SNPs) have been identified in the DNA sequences of GPX1 gene, however, only the Pro198Leu (also known as rs1050450, noted in NCBI database as position 200 and it has also been recorded to at position 197) polymorphism has been extensively investigated. Previous studies have demonstrated the association between low level of circulating GPX1 and increased risk of cancer, which was found in several types of cancers including breast cancer [7,8], lung cancer [9], prostate cancer [10], and colorectal cancer [11]. As with the presumption, GPX1 Pro198Leu (C>T) polymorphism affected GPX1 activity, which might further play an important role in cancer development. However, possible relationships between GPX1 polymorphism and cancer have been studied only in separate types of cancer with conflicting results. Thus, we conducted a comprehensive meta-analysis to explore the association of GPX1 Pro198Leu (rs1050450) polymorphism with risk for cancer and investigated each individual tumor in subgroup analysis.
Methods
Study selection
PubMed, Embase, Science Direct, and Cochrane Library were searched on October 17, 2016 using the mesh terms: “glutathione peroxidase1 or GPX1”, “polymorphism or variant or mutation” and “cancer or carcinoma or malignancy”. There was no language restriction. All searched results underwent abstract review and potentially eligible studies were reviewed through whole text. Additional potential eligible studies regarding this topic were identified through the references in retrieved articles.
Inclusion and exclusion criteria
In our meta-analysis, we used the following inclusion criteria: (1) case-control studies or cohort studies, (2) studies investigating the relationship between GPX1 (rs1050450) polymorphism and cancer risk, and (3) Odds ratio (OR) with 95% confidence interval (CI) being applied to assess the strength of association. Studies were excluded if they met the following criteria: (1) in vitro studies or review articles, (2) duplicated publications, and (3) reports with incomplete data. If studies used overlapped cases, only the study with the largest sample size was enrolled.
Data extraction
Two investigators extracted all data independently, and a consensus was reached prior to further process. For one publication with several cancer types, each type was treated separately. From each study, the following basic characteristics were extracted: first author’s name, year of publication, country of origin, ethnicity of the study population, source of control groups (population-based or hospital-based controls), genotyping methods, total number of cancer cases and controls, and genotype distributions of cases and controls.
Statistical analysis
The following genotype contrasts were evaluated: dominate genetic model (CT+TT vs CC), recessive genetic model (TT vs CT+CC), homozygote comparison (TT vs CC), heterozygote comparison (CT vs CC), and allele comparison (T vs C). The association between GPX1 Pro198Leu polymorphism and cancer risk was measured using the odds ratio (OR) with 95% confidence interval (95% CI). The significance of the pooled OR was determined by the Z test and P value less than 0.05 indicated that the result was of statistical significance. In addition, subgroup analysis according to cancer types and ethnicity were performed. In terms of heterogeneity, P<0.10 or I2>50% represented that heterogeneity existed in pooled ORs. When homogeneity was acceptable (P≥0.10, I2≤50%), a fixed-effects model was applied to secondary analysis; otherwise, a random-effects model was used [12,13]. Publication bias was assessed by Begg’s funnel plot and Egger’s linear regression test. We also further performed sensitivity analysis to evaluate the stability of our results. All P values were two-sided. All analyses were performed using STATA 12.0 (STATA Corporation, College Station, TX).
Results
Characteristics of eligible studies
According to our searching strategy, a total of 52 publications with 60 case-control studies were included in this meta-analysis, with 21,296 cancer patients and 30,346 controls. The study selection process was shown in (Figure 1). The baseline characteristics of included studies and genotype distributions were summarized in Tables 1 and 2. These 60 case-control studies were published from 2000 to 2016, among which there were 11 studies regarding prostate cancer, 10 studies on breast cancer, 6 studies about brain tumors (including acoustic neuroma, glioma, glioblastoma, multiforme, and meningioma), 6 studies on lung cancer, 5 studies regarding bladder cancer, 5 studies on colorectal cancer, 4 studies regarding skin cancer (including basal cell carcinoma, squamous cell carcinoma, and melanoma), 4 studies on non-Hodgkin lymphoma (NHL), 2 studies about hepatocellular carcinoma, 1 study on gastric cancer, 2 studies on myeloid leukemia, 3 studies regarding head and neck cancer (including laryngeal cancer and oral cavity cancer), and 1 study on pancreatic cancer. In all 52 included publications, 40 reports were analyzing Caucasian, 6 reports from Asian, 2 reports of African-Americans, and 12 reports of mixed ethnicity. Diverse genotyping methods were used in the included studies, various from polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), TaqMan, general PCR, and Matrix-Assisted Laser Desorption/Ionization Time of Flight Mass Spectrometry (MALDI/TOF).
Figure 1.

Flow chart of study selection in this meta-analysis.
Table 1.
Baseline characteristics of eligible studies
| First Author | No.# | Year | Country | Ethnicity | Source of Controls | Sample | Quality Control | Control Health | Cancer Type | Case/Control | Genotyping method | HWE |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Abe [14] | 2011 | USA | Caucasian | PB | Blood | NA | NA | Prostate cancer | 356/745 | PCR | Yes | |
| Ahn [15] | 2005 | USA | Caucasian | PB | Blood | Yes | NA | Breast cancer | 1038/1088 | MALDI-TOF | Yes | |
| Arsova-Sarafinovska [10] | 2009 | Macedonia | Caucasian | HB | Blood | NA | NA | Prostate cancer | 82/123 | PCR | Yes | |
| Aynali [16] | 2013 | Turkey | Caucasian | HB | Blood | NA | Health | Laryngeal cancer | 25/23 | PCR | No | |
| Banescu [17] | 2014 | Romania | Caucasian | HB | Blood | NA | Health | CML | 168/321 | PCR-RFLP | Yes | |
| Banescu [18] | 2016 | Romania | Caucasian | HB | Blood | NA | Health | AML | 102/303 | PCR-RFLP | No | |
| Bhatti [19] | 1 | 2009 | USA | Caucasian | HB | Blood | Yes | Unhealth | Glioma | 327/457 | TaqMan | NA |
| Bhatti [19] | 2 | 2009 | USA | Caucasian | HB | Blood | Yes | Unhealth | Glioblastoma multiforme | 157/457 | TaqMan | NA |
| Bhatti [19] | 3 | 2009 | USA | Caucasian | HB | Blood | Yes | Unhealth | Meningioma | 121/457 | TaqMan | NA |
| Cebrian [20] | 2006 | UK | Caucasian | PB | Blood | Yes | NA | Breast cancer | 2293/2278 | TaqMan | Yes | |
| Cheng [21] | 2011 | USA | Mixed | PB | Blood | NA | NA | Prostate cancer | 150/761 | PCR | NA | |
| Choi [22] | 1 | 2007 | USA | Caucasian | PB | Blood | Yes | Health | Prostate cancer | 452/1221 | MALDI-TOF | Yes |
| Choi [22] | 2 | 2007 | USA | African American | PB | Blood | Yes | Health | Prostate cancer | 29/119 | MALDI-TOF | Yes |
| Cox [23] | 2004 | USA | Caucasian | PB | Blood | NA | NA | Breast cancer | 1323/1910 | TaqMan | Yes | |
| Erdem [24] | 2012 | Turkey | Caucasian | HB | Blood | NA | NA | Prostate cancer | 33/91 | PCR | Yes | |
| Ermolenko [25] | 2010 | Russia | Caucasian | HB | Blood | NA | NA | Breast cancer | 927/474 | PCR TaqMan | Yes | |
| Ezzikouri [26] | 2010 | France | Caucasian | HB | Blood | Yes | Health (163) HCV(59) | Hepatocellular carcinoma | 96/222 | PCR-RFLP | Yes | |
| Goerlitz [27] | 2011 | Egypt | Caucasian | PB | NA | Yes | NA | Bladder Cancer | 625/626 | TaqMan | Yes | |
| Hansen [28] | 2005 | Norway | Caucasian | PB | Blood | NA | NA | Colorectal cancer | 166/397 | PCR | Yes | |
| Hansen [11] | 2009 | Denmark | Caucasian | PB | Blood | Yes | NA | Colorectal cancer | 375/779 | PCR | Yes | |
| He [29] | 1 | 2010 | USA | Caucasian | PB | NA | NA | NA | Melanoma | 207/809 | TaqMan | Yes |
| He [29] | 2 | 2010 | USA | Caucasian | PB | NA | NA | NA | SCC | 257/809 | TaqMan | Yes |
| He [29] | 3 | 2010 | USA | Caucasian | PB | NA | NA | NA | BCC | 281/809 | TaqMan | Yes |
| Hu [8] | 2003 | Canada | African American | PB | Blood | Yes | NA | Breast cancer | 79/517 | PCR | Yes | |
| Hu [30] | 2004 | USA | Mixed | HB | Blood | NA | NA | Head and neck cancer | 133/517 | PCR | Yes | |
| Hu [31] | 2005 | USA | Mixed | HB | Blood | Yes | NA | Colon cancer | 53/53 | PCR | Yes | |
| Ichimura [32] | 2004 | Japan | Asian | HB | Blood | Yes | Health | Bladder cancer | 213/209 | PCR-RFLP | Yes | |
| Jablonska [33] | 2015 | Poland | Caucasian | HB | Blood | Yes | Health | Breast cancer | 136/183 | PCR | Yes | |
| Karunasinghe [34] | 2013 | New Zealand | Mixed | HB | Blood | NA | Health | Prostate cancer | 410/441 | PCR | Yes | |
| Knight [35] | 2004 | Canada | Caucasian | PB | Blood | NA | NA | Breast cancer | 399/372 | TaqMan | Yes | |
| Kucukgergin [36] | 1 | 2011 | Turkey | Caucasian | HB | Blood | NA | Health | Prostate cancer | 134/159 | PCR-RFLP | Yes |
| Kucukgergin [37] | 2 | 2012 | Turkey | Caucasian | HB | Blood | NA | Health | Bladder cancer | 157/224 | PCR-RFLP | Yes |
| Lan [38] | 2007 | USA | Caucasian | PB | Blood | Yes | NA | NHL | 449/520 | PCR | No | |
| Lee [39] | 2006 | Korea | Asian | HB | Blood | NA | NA | Lung cancer | 200/200 | PCR | Yes | |
| Lightfoot [40] | 1 | 2006 | UK | Caucasian | PB | Blood | NA | NA | NHL-UK | 620/762 | TaqMan | Yes |
| Lightfoot [40] | 2 | 2006 | USA | Caucasian | PB | Blood | NA | NA | NHL-USA | 308/684 | TaqMan | Yes |
| Meplan [41] | 2013 | Denmark | Caucasian | PB | Blood | NA | NA | Breast cancer | 933/959 | PCR | Yes | |
| Meplan [42] | 2010 | Czech | Caucasian | HB | Blood | Yes | Health | Colorectal cancer | 681/637 | PCR | No | |
| Oskina NA [43] | 2014 | Russia | Caucasian | HB | Blood | NA | NA | Prostate cancer | 361/326 | TaqMan | Yes | |
| Parlaktas [44] | 2015 | Turkey | Caucasian | HB | Blood | NA | Health | Prostate cancer | 49/49 | PCR | Yes | |
| Paz-y-Miño [45] | 2010 | Ecuador | Mixed | PB | Blood | NA | NA | Bladder cancer | 97/120 | PCR-RFLP | Yes | |
| Peters [46] | 2008 | USA | Mixed | PB | Blood | Yes | NA | Colorectal cancer | 772/777 | TaqMan | Yes | |
| Raaschou-Nielsen [9] | 2007 | Denmark | Caucasian | PB | Blood | NA | NA | Lung cancer | 432/798 | PCR | Yes | |
| Rajaraman [47] | 1 | 2008 | USA | Mixed | HB | Blood | Yes | Unhealth | Acoustic neuroma | 69/494 | TaqMan | Yes |
| Rajaraman [47] | 2 | 2008 | USA | Mixed | HB | Blood | Yes | Unhealth | Meningioma | 134/494 | TaqMan | Yes |
| Rajaraman [47] | 3 | 2008 | USA | Mixed | HB | Blood | Yes | Unhealth | Glioma | 362/494 | TaqMan | Yes |
| Ratnasinghe [48] | 2000 | Finland | Caucasian | PB | Blood | Yes | NA | Lung cancer | 315/313 | TaqMan | Yes | |
| Ravn-Haren [7] | 2006 | Denmark | Caucasian | PB | Blood | Yes | NA | Breast cancer | 377/377 | PCR | Yes | |
| Reszka [49] | 2009 | Poland | Caucasian | HB | Blood | NA | Health | Bladder cancer | 33/47 | PCR | Yes | |
| Rosenberger [50] | 2008 | Germany | Caucasian | PB | Blood | Yes | NA | Lung cancer | 186/207 | MALDI-TOF | Yes | |
| Skuladottir [51] | 2005 | Denmark | Caucasian | PB | Blood | NA | NA | Lung cancer | 320/618 | PCR | NA | |
| Steinbrecher [52] | 2010 | Germany | Caucasian | PB | Blood | NA | Health | Prostate cancer | 248/492 | MALDI-TOF | Yes | |
| Su [53] | 2015 | China | Asian | HB | Blood | Yes | NA | Hepatocellular carcinoma | 434/480 | PCR-RFLP | Yes | |
| Tang [54] | 2010 | USA | Mixed | HB | Blood | NA | Health | Pancreatic cancer | 575/648 | PCR | Yes | |
| Tsai [55] | 2012 | China | Asian | HB | Blood | Yes | Health | Breast cancer | 260/224 | PCR | No | |
| Vogel [56] | 2004 | Denmark | Caucasian | PB | Blood | NA | NA | Basal Cell Carcinoma | 317/317 | PCR | Yes | |
| Wang [57] | 2008 | China | Asian | HB | Blood | NA | NA | Gastric cancer | 361/363 | PCR-RFLP | Yes | |
| Wang [58] | 2006 | USA | Mixed | PB | Blood | Yes | NA | NHL | 740/636 | TaqMan | Yes | |
| Wu [59] | 2010 | China | Asian | HB | Blood | NA | Health | Oral cavity cancer | 122/122 | PCR | Yes | |
| Yang [4] | 2004 | USA | Mixed | HB | Blood | Yes | NA | Lung cancer | 237/234 | PCR | No |
number of data separately reported by articles.
HWE, Hardy-Weinberg equilibrium; MALDI-TOF, Matrix-Assisted Laser Desorption/Ionization Time of Flight Mass Spectrometry; PCR, polymerase chain reaction; PCR-RFLP, polymerase chain reaction-restriction fragment length polymorphism; PB, population-based; HB, hospital-based; NA, not available; CML, Chronic myeloid leukemia; NHL, non-Hodgkin lymphoma; BCC, Basal cell carcinoma; SCC, Squamous cell carcinoma.
Table 2.
Genotype frequency distribution of GPX1 gene polymorphism
| First Author | No.# | Ethnicity | Cancer Type | System | Case | Control | HWE | ||||
|---|---|---|---|---|---|---|---|---|---|---|---|
|
|
|
||||||||||
| TT | CC | CT | TT | CC | CT | ||||||
| Abe [14] | Caucasian | Prostate cancer | Prostate cancer | 169 | 137 | 50 | 340 | 314 | 91 | Yes | |
| Ahn [15] | Caucasian | Breast cancer | Breast cancer | 472 | 456 | 110 | 523 | 453 | 112 | Yes | |
| Arsova-Sarafinovska [10] | Caucasian | Prostate cancer | Prostate cancer | 54 | 17 | 11 | 57 | 47 | 19 | Yes | |
| Aynali [16] | Caucasian | Laryngeal cancer | Head and neck cancer | 0 | 23 | 2 | 0 | 20 | 3 | No | |
| Banescu [17] | Caucasian | CML | Hematological malignancies | 16 | 118 | 34 | 34 | 203 | 84 | Yes | |
| Banescu [18] | Caucasian | AML | Hematological malignancies | 3 | 28 | 71 | 34 | 190 | 79 | No | |
| Bhatti [19] | 1 | Caucasian | Glioma | Brain cancer | 158 | 169 | 236 | 221 | NA | ||
| Bhatti [19] | 2 | Caucasian | Glioblastoma multiforme | Brain cancer | 74 | 83 | 236 | 221 | NA | ||
| Bhatti [19] | 3 | Caucasian | Meningioma | Brain cancer | 55 | 66 | 236 | 221 | NA | ||
| Cebrian [20] | Caucasian | Breast cancer | Breast cancer | 1109 | 964 | 220 | 1066 | 993 | 219 | Yes | |
| Cheng [21] | Mixed | Prostate cancer | Prostate cancer | 49 | 53 | 371 | 342 | NA | |||
| Choi [22] | 1 | Caucasian | Prostate cancer | Prostate cancer | 227 | 190 | 35 | 616 | 515 | 90 | Yes |
| Choi [22] | 2 | African American | Prostate cancer | Prostate cancer | 12 | 15 | 2 | 51 | 53 | 15 | Yes |
| Cox [23] | Caucasian | Breast cancer | Breast cancer | 581 | 515 | 133 | 774 | 694 | 161 | Yes | |
| Erdem [24] | Caucasian | Prostate cancer | Prostate cancer | 11 | 17 | 5 | 40 | 41 | 10 | Yes | |
| Ermolenko [25] | Caucasian | Breast cancer | Breast cancer | 452 | 375 | 100 | 192 | 230 | 52 | Yes | |
| Ezzikouri [26] | Caucasian | Hepatocellular carcinoma | Digestive system cancer | 50 | 32 | 14 | 108 | 88 | 26 | Yes | |
| Goerlitz [27] | Caucasian | Bladder Cancer | Bladder Cancer | 330 | 236 | 46 | 326 | 254 | 38 | Yes | |
| Hansen [28] | 1 | Caucasian | Colorectal cancer | Digestive system cancer | 82 | 68 | 16 | 196 | 163 | 38 | Yes |
| Hansen [11] | 2 | Caucasian | Colorectal cancer | Digestive system cancer | 173 | 164 | 38 | 342 | 348 | 89 | Yes |
| He [29] | 1 | Caucasian | Melanoma | Skin cancer | 94 | 86 | 27 | 419 | 327 | 63 | Yes |
| He [29] | 2 | Caucasian | SCC | Skin cancer | 128 | 107 | 22 | 419 | 327 | 63 | Yes |
| He [29] | 3 | Caucasian | BCC | Skin cancer | 141 | 124 | 16 | 419 | 327 | 63 | Yes |
| Hu [30] | African American | Breast cancer | Breast cancer | 36 | 25 | 18 | 244 | 209 | 64 | Yes | |
| Hu [30] | Mixed | Head and neck cancer | Head and neck cancer | 69 | 30 | 34 | 244 | 209 | 64 | Yes | |
| Hu [31] | Mixes | Colon cancer | Digestive system cancer | 33 | 15 | 5 | 24 | 26 | 3 | Yes | |
| Ichimura [32] | Asian | Bladder cancer | Bladder cancer | 166 | 47 | 0 | 187 | 22 | 0 | Yes | |
| Jablonska [33] | Caucasian | Breast cancer | Breast cancer | 73 | 51 | 12 | 75 | 85 | 23 | Yes | |
| Karunasinghe [34] | Mixed | Prostate cancer | Prostate cancer | 122 | 110 | 30 | 216 | 186 | 33 | Yes | |
| Knight [35] | Caucasian | Breast cancer | Breast cancer | 192 | 171 | 34 | 169 | 164 | 39 | Yes | |
| Kucukgergin [36] | 1 | Caucasian | Prostate cancer | Prostate cancer | 32 | 62 | 40 | 78 | 61 | 20 | Yes |
| Kucukgergin [37] | 2 | Caucasian | Bladder cancer | Bladder cancer | 63 | 64 | 30 | 117 | 87 | 20 | Yes |
| Lan [38] | Caucasian | NHL | Hematological malignancies | 215 | 191 | 43 | 261 | 200 | 59 | No | |
| Lee [39] | Asian | Lung cancer | Lung cancer | 116 | 84 | 0 | 154 | 46 | 0 | Yes | |
| Lightfoot [40] | 1 | Caucasian | NHL-UK | Hematological malignancies | 311 | 259 | 43 | 438 | 268 | 55 | Yes |
| Lightfoot [40] | 2 | Caucasian | NHL-USA | Hematological malignancies | 142 | 128 | 38 | 335 | 283 | 65 | Yes |
| Meplan [41] | Caucasian | Breast cancer | Breast cancer | 465 | 396 | 72 | 503 | 370 | 86 | Yes | |
| Meplan [42] | Caucasian | Colorectal cancer | Digestive system cancer | 354 | 306 | 21 | 355 | 259 | 23 | No | |
| Oskina NA [43] | Caucasian | Prostate cancer | Prostate cancer | 183 | 146 | 32 | 153 | 132 | 41 | Yes | |
| Parlaktas [44] | Caucasian | Prostate cancer | Prostate cancer | 27 | 16 | 6 | 24 | 17 | 8 | Yes | |
| Paz-y-Miño [45] | Mixed | Bladder cancer | Bladder cancer | 28 | 19 | 50 | 73 | 42 | 5 | Yes | |
| Peters [46] | Mixed | Colorectal cancer | Digestive system cancer | 351 | 288 | 77 | 355 | 331 | 57 | Yes | |
| Raaschou-Nielsen [9] | Caucasian | Lung cancer | Lung cancer | 209 | 184 | 39 | 348 | 358 | 92 | Yes | |
| Rajaraman [47] | 1 | Mixed | Acoustic neuroma | Brain cancer | 28 | 30 | 7 | 236 | 178 | 46 | Yes |
| Rajaraman [47] | 2 | Mixed | Meningioma | Brain cancer | 57 | 56 | 10 | 236 | 178 | 46 | Yes |
| Rajaraman [47] | 3 | Mixed | Glioma | Brain cancer | 165 | 140 | 35 | 236 | 178 | 46 | Yes |
| Ratnasinghe [48] | Caucasian | Lung cancer | Lung cancer | 91 | 157 | 67 | 132 | 135 | 46 | Yes | |
| Ravn-Haren [7] | Caucasian | Breast cancer | Breast cancer | 176 | 168 | 33 | 205 | 136 | 36 | Yes | |
| Reszka [49] | Caucasian | Bladder cancer | Bladder cancer | 13 | 15 | 5 | 27 | 18 | 1 | Yes | |
| Rosenberger [50] | Caucasian | Lung cancer | Lung cancer | 114 | 63 | 9 | 97 | 89 | 21 | Yes | |
| Skuladottir [51] | Caucasian | Lung cancer | Lung cancer | 50 | 69 | 172 | 185 | NA | |||
| Steinbrecher [52] | Caucasian | Prostate cancer | Prostate cancer | 123 | 108 | 16 | 264 | 181 | 42 | Yes | |
| Su [53] | Asian | Hepatocellular carcinoma | Digestive system cancer | 371 | 19 | 0 | 454 | 27 | 0 | Yes | |
| Tang [54] | Mixed | Pancreatic cancer | Digestive system cancer | 263 | 240 | 49 | 316 | 242 | 58 | Yes | |
| Tsai [55] | Asian | Breast cancer | Breast cancer | 247 | 13 | 0 | 166 | 58 | 0 | No | |
| Vogel [56] | Caucasian | Basal Cell Carcinoma | Skin cancer | 150 | 136 | 31 | 151 | 139 | 27 | Yes | |
| Wang [57] | Asian | Gastric cancer | Digestive system cancer | 315 | 44 | 2 | 326 | 35 | 2 | Yes | |
| Wang [58] | Mixed | NHL | Hematological malignancies | 360 | 310 | 70 | 291 | 284 | 61 | Yes | |
| Wu [59] | Asian | Oral cavity cancer | Head and neck cancer | 108 | 12 | 0 | 112 | 10 | 0 | Yes | |
| Yang [4] | Mixed | Lung cancer | Lung cancer | 111 | 98 | 20 | 114 | 85 | 29 | No | |
number of data separately reported by articles.
HWE, Hardy-Weinberg equilibrium; CML, Chronic myeloid leukemia; AML, Acute myeloid leukemia; NHL, non-Hodgkin lymphoma; BCC, Basal cell carcinoma; SCC, Squamous cell carcinoma.
Pooled analysis
When all collected data were pooled into the meta-analysis, results showed that significant associations were found regarding to the following three genetic models (TT vs CT+CC: OR = 1.15, 95% CI = 1.01-1.32, P = 0.042; TT vs CC: OR = 1.15, 95% CI = 1.00-1.31, P = 0.044; T vs C: OR = 1.09, 95% CI = 1.01-1.17, P = 0.02), respectively (Figure 2). As for stratified analyses by cancer types, HWE and ethnicity, the pooled ORs for additive model and recessive model comparison suggested GPX1 (rs1050450) polymorphism was significantly associated with an increased risk of bladder cancer (TT+CT vs CC: OR = 1.72, 95% CI = 1.09-2.70, P = 0.019; TT vs CT+CC: OR = 3.56, 95% CI = 1.42-8.94, P = 0.007; TT vs CC: OR = 3.75, 95% CI = 1.41-9.94, P = 0.008; T vs C: OR = 1.94, 95% CI = 1.17-3.22, P = 0.01), and a relative association was found in head and neck cancer (TT vs CT+CC: OR = 2.19, 95% CI = 1.39-3.46, P = 0.001) and brain cancer (TT+CT vs CC: OR = 1.19, 95% CI = 1.03-1.37, P = 0.018). However, in prostate cancer, breast cancer, NHL, lung cancer and digestive system cancer, significant association was not found in any genetic model (all P>0.05). The association between GPX1 rs1050450 polymorphism and susceptibility to cancer was further proved in subgroup with controls consistent with Hardy-Weinberg equilibrium (TT+CT vs CC: OR = 1.07, 95% CI = 1.00-1.15, P = 0.041; T vs C: OR = 1.08, 95% CI = 1.01-1.15, P = 0.025). In subgroup analysis stratified by ethnicity, no associations were appreciated in Caucasian population (OR = 1.06, 95% CI = 0.98-1.15, P = 0.132), Asians (OR = 1.04, 95% CI = 0.47-2.30, P = 0.915), African-Americans (OR = 1.066, 95% CI = 0.71-1.61, P = 0.76), or mixed ethnicity population (OR = 1.11, 95% CI = 0.94-1.30, P = 0.216). The main results of the meta-analysis were summarized in Table 3.
Figure 2.

Forest plot for the association between the GPX1 rs1050450 polymorphism and cancer risk (T vs C). We detected significant association between the GPX1 rs1050450 polymorphism and cancer susceptibility.
Table 3.
The results of evidence synthesis in this meta-analysis
| Variables | Dominant model (TT+CT vs CC) | Recessive model (TT vs CT+CC) | Homozygote model (TT vs CC) | Heterozygote model (CT vs CC) | Allel contrast model (T vs C) | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
|
|
|
|
|
|||||||||||
| OR (95% CI) | P | I2 (%) | OR (95% CI) | P | I2 (%) | OR (95% CI) | P | I2 (%) | OR (95% CI) | P | I2 (%) | OR (95% CI) | P | I2 (%) | |
| All | 1.08 (1.00-1.17) | 0.051 | 70.50 | 1.15 (1.01-1.32) | 0.042 | 72.00 | 1.15 (1.00-1.31) | 0.044 | 66.60 | 1.03 (0.95-1.12) | 0.42 | 67.80 | 1.09 (1.01-1.17) | 0.02 | 79.90 |
| By cancer type | |||||||||||||||
| Prostate cancer | 1.07 (0.87-1.32) | 0.512 | 67.80 | 1.10 (0.81-1.48) | 0.546 | 55.50 | 1.12 (0.77-1.64) | 0.556 | 69.30 | 1.04 (0.84-1.29) | 0.694 | 61.20 | 1.06 (0.87-1.28) | 0.573 | 75.70 |
| Breast cancer | 0.87 (0.72-1.05) | 0.132 | 85.60 | 0.98 (0.88-1.09) | 0.711 | 0.00 | 0.97 (0.86-1.09) | 0.57 | 0.00 | 0.87 (0.71-1.06) | 0.163 | 86.10 | 0.91 (0.80-1.04) | 0.148 | 82.40 |
| Head and neck cancer | 0.88 (0.62-1.25) | 0.491 | 0.00 | 2.19 (1.39-3.46) | 0.001 | 52.30 | NA | NA | NA | 0.73 (0.31-1.74) | 0.482 | 67.90 | 1.17 (0.91-1.51) | 0.215 | 0.00 |
| Hematological malignancies | 1.13 (0.94-1.37) | 0.203 | 55.70 | 1.29 (0.73-2.30) | 0.383 | 91.00 | 1.20 (0.82-1.76) | 0.341 | 69.10 | 1.11 (0.99-1.25) | 0.082 | 37.00 | 1.22 (0.95-1.57) | 0.125 | 88.30 |
| Brain cancer | 1.19 (1.03-1.37) | 0.018 | 0.00 | 0.98 (0.69-1.39) | 0.886 | 0.00 | 1.07 (0.74-1.54) | 0.735 | 0.00 | 1.22 (0.98-1.52) | 0.082 | 0.00 | 1.1 (0.94-1.29) | 0.244 | 0.00 |
| Digestive system cancer | 1.02 (0.93-1.13) | 0.65 | 7.90 | 1.07 (0.89-1.29) | 0.464 | 0.00 | 1.06 (0.87-1.29) | 0.559 | 0.00 | 1.01 (0.91-1.12) | 0.803 | 35.10 | 1.03 (0.95-1.11) | 0.507 | 0.00 |
| Bladder cancer | 1.72 (1.09-2.70) | 0.019 | 82.70 | 3.56 (1.42-8.94) | 0.007 | 87.40 | 3.75 (1.41-9.94) | 0.008 | 87.80 | 1.24 (0.89-1.74) | 0.203 | 62.10 | 1.94 (1.17-3.22) | 0.01 | 91.90 |
| Skin cancer | 1.11 (0.96-1.28) | 0.175 | 0.00 | 1.15 (0.89-1.49) | 0.293 | 49.10 | 1.19 (0.91-1.56) | 0.202 | 48.20 | 1.09 (0.94-1.27) | 0.275 | 0.00 | 1.09 (0.97-1.22) | 0.132 | 14.70 |
| Lung cancer | 1.17 (0.79-1.75) | 0.431 | 87.00 | 0.82 (0.49-1.37) | 0.445 | 73.90 | 0.82 (0.41-1.66) | 0.588 | 84.70 | 1.19 (0.77-1.86) | 0.433 | 86.80 | 1.07 (0.74-1.55) | 0.709 | 89.60 |
| By ethnicity | |||||||||||||||
| Caucasian | 1.06 (0.98-1.15) | 0.132 | 63.80 | 1.08 (0.94-1.25) | 0.276 | 68.20 | 1.08 (0.94-1.24) | 0.304 | 62.30 | 1.04 (0.96-1.12) | 0.362 | 57.60 | 1.06 (0.98-1.14) | 0.139 | 75.60 |
| Mixed | 1.11 (0.94-1.30) | 0.216 | 64.30 | 1.44 (0.98-2.11) | 0.067 | 82.00 | 1.41 (0.98-2.04) | 0.065 | 78.20 | 0.99 (0.85-1.16) | 0.943 | 53.80 | 1.19 (0.98-1.45) | 0.077 | 85.20 |
| AfricanAmerican | 1.07 (0.71-1.61) | 0.76 | 0.00 | 1.24 (0.32-4.76) | 0.751 | 65.10 | 1.56 (0.88-2.77) | 0.133 | 48.00 | 0.91 (0.58-1.43) | 0.679 | 0.00 | 1.19 (0.88-1.61) | 0.258 | 0.00 |
| Asian | 1.04 (0.47-2.30) | 0.915 | 91.60 | NA | NA | NA | NA | NA | NA | 1.05 (0.47-2.32) | 0.912 | 91.60 | 1.02 (0.50-2.07) | 0.954 | 90.50 |
| By HWE | |||||||||||||||
| Yes | 1.07 (1.00-1.15) | 0.041 | 62.20 | 1.11 (0.99-1.25) | 0.081 | 61.60 | 1.13 (0.99-1.29) | 0.059 | 64.30 | 1.04 (0.97-1.11) | 0.336 | 56.60 | 1.08 (1.01-1.15) | 0.025 | 73.10 |
| No | 0.82 (0.17-4.09) | 0.809 | 94.40 | 2.08 (0.22-19.66) | 0.523 | 97.00 | 2.55 (0.17-37.87) | 0.496 | 93.50 | 0.64 (0.14-3.01) | 0.575 | 93.70 | 0.86 (0.21-3.54) | 0.836 | 97.20 |
P, P-value of Z-test to evaluate the significance of the ORs; NA, not available.
Publication bias and sensitivity analysis
Begg’s (Pr>|z| = 0.245) and Egger’s (P>|t| = 0.132) test was performed to assess the publication bias of pooled literatures, which was shown in the (Figure 3). The shapes of the funnel plots were symmetrical in the dominant genetic models, which indicated that the publication bias did not emerge in the cohort. When dropping each study in sensitivity analysis, the results of the meta-analysis didn’t change, which suggested the reliability of the results.
Figure 3.

Begg’s funnel plot and Egger’s on publication bias for included studies on the association of the GPX1 rs1050450 polymorphism and cancer susceptibility (TT vs CT+CC). The funnel plot seemed symmetrical, suggesting absence of publication bias.
Discussion
The current meta-analysis, including 21,296 cancer patients and 30,346 controls from 60 case-control studies, investigated the relationship between the GPX1 (rs1050450) polymorphism and cancer risk. To the best of our knowledge, this was the first meta-analysis in such a large sample size with comprehensive evaluation of the association between the polymorphism of GPX1 and the tumor risk. We found that individuals with TT/CT genotypes harbored increased risk of cancer, especially in patients with bladder cancer as shown in the subgroup analysis.
Oxidative stress is an inevitable result of aerobic life. Previous studies have suggested that reactive oxygen species (ROS)-related oxidative damage plays a vital role in carcinogenesis [1]. ROS are modulated by regular metabolic process in vivo and can initiate a series of free radical formation. ROS can result in the breakage of DNA, oxidization of proteins and lipid [2]. DNA damages may inactivate cancer suppressor genes and further reduce the integrity of genome [37]. GPX1 plays a crucial role in the detoxification of mitochondrial ROS. High level expression of GPX1 could increase the antioxidant capacity in one cell, thus reducing intracellular oxidative stress. The appropriate adjustment of GPX1 levels has been considered as a significant factor in different stages of carcinogenesis both in vitro and vivo experiments [60]. Accumulating evidences have demonstrated that the GPX1 (rs1050450 C>T) polymorphism may increase carcinogenesis risk. According to our study, the result indicated that individuals with the CT/TT (ProLeu/LeuLeu) genotypes were associated with a higher risk of cancer than subjects carrying the wild ProPro genotype.
Since cancer origins could influence the outcomes as shown in previous studies, we conducted subgroup analysis according to cancer types. Except for bladder cancer and brain tumor, we did not find any positive association regarding to prostate cancer, breast cancer, lung cancer, colorectal cancer, NHL, skin cancer, digestive system cancer and head and neck cancer. Prostate cancer and bladder cancer are two of the most common urological malignancies. Previous studies suggested that the association of GPX1 (rs1050450) polymorphism with prostate cancer and bladder cancer was inconclusive [22,27,34,37]. Therefore, current meta-analysis was designed to determine a more accurate role of GPX (rs1050450 C>T) polymorphism since this meta-analysis investigated a large number of individuals and could also estimate the effect of genetic factors [8]. In addition, we previously put forward that only two studies reported African-Americans and only five studies reported Asian population. Hence, larger-sample studies and combined analysis are warranted to further verify the role of ethnic discrepancy in the relationship of the GPX1 polymorphism and cancer risks, especially for African-Americans and Asians.
In interpreting current results, several limitations of the meta-analysis should be addressed. First, as only publications indexed by selected databases were included in the current study, some relevant published studies with null results were missing and ongoing studies with unpublished data were unavailable, which may have influenced our results. Second, part of the studies investigated comparing several different sets of cases with the same set of control, which might reduce the statistical power for identifying those possible associations. Third, the lack of the original data of the reviewed studies limited our further evaluation of the potential interactions. In the meantime, current study also had some merits. For one thing, over 60 studies were pooled from 52 publications, which significantly increased statistical power of the analysis. For another, on the basis of our studies, we found a novel way to predict the association between GPX (rs1050450 C>T) polymorphism and cancer risk, especially in bladder cancer.
To summarize, the results from the meta-analysis provided some evidence that the GPX1 Pro198Leu (rs1050450 C>T) polymorphism might contribute to genetic susceptibility to cancer especially in bladder cancer, supporting the hypothesis that the polymorphism could serve as a potential tumor predicting biomarker. However, the conclusion should be interpreted with caution. The detailed analysis of genetic models and inclusion of large-scale studies regarding African-Americans and Asians, and comprehensive study design with respect to gene-gene and gene-environment interaction are warranted.
Acknowledgements
This work was funded by the National Natural Science Foundation of China (Grant No. 81171320).
Disclosure of conflict of interest
None.
References
- 1.Chen W, Zheng R, Baade PD, Zhang S, Zeng H, Bray F, Jemal A, Yu XQ, He J. Cancer statistics in China, 2015. CA Cancer J Clin. 2016;66:115–132. doi: 10.3322/caac.21338. [DOI] [PubMed] [Google Scholar]
- 2.Hanahan D, Weinberg RA. Hallmarks of cancer: the next generation. Cell. 2011;144:646–674. doi: 10.1016/j.cell.2011.02.013. [DOI] [PubMed] [Google Scholar]
- 3.Kamarajugadda S, Cai Q, Chen H, Nayak S, Zhu J, He M, Jin Y, Zhang Y, Ai L, Martin SS, Tan M, Lu J. Manganese superoxide dismutase promotes anoikis resistance and tumor metastasis. Cell Death Dis. 2013;4:e504. doi: 10.1038/cddis.2013.20. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 4.Yang P, Bamlet WR, Ebbert JO, Taylor WR, de Andrade M. Glutathione pathway genes and lung cancer risk in young and old populations. Carcinogenesis. 2004;25:1935–1944. doi: 10.1093/carcin/bgh203. [DOI] [PubMed] [Google Scholar]
- 5.Glebova K, Veiko N, Kostyuk S, Izhevskaya V, Baranova A. Oxidized extracellular DNA as a stress signal that may modify response to anticancer therapy. Cancer Lett. 2015;356:22–33. doi: 10.1016/j.canlet.2013.09.005. [DOI] [PubMed] [Google Scholar]
- 6.Spanier G, Xu H, Xia N, Tobias S, Deng S, Wojnowski L, Forstermann U, Li H. Resveratrol reduces endothelial oxidative stress by modulating the gene expression of superoxide dismutase 1 (SOD1), glutathione peroxidase 1 (GPx1) and NADPH oxidase subunit (Nox4) J Physiol Pharmacol. 2009;60(Suppl 4):111–116. [PubMed] [Google Scholar]
- 7.Ravn-Haren G, Olsen A, Tjonneland A, Dragsted LO, Nexo BA, Wallin H, Overvad K, Raaschou-Nielsen O, Vogel U. Associations between GPX1 Pro198Leu polymorphism, erythrocyte GPX activity, alcohol consumption and breast cancer risk in a prospective cohort study. Carcinogenesis. 2006;27:820–825. doi: 10.1093/carcin/bgi267. [DOI] [PubMed] [Google Scholar]
- 8.Hu YJ, Diamond AM. Role of glutathione peroxidase 1 in breast cancer: loss of heterozygosity and allelic differences in the response to selenium. Cancer Res. 2003;63:3347–3351. [PubMed] [Google Scholar]
- 9.Raaschou-Nielsen O, Sorensen M, Hansen RD, Frederiksen K, Tjonneland A, Overvad K, Vogel U. GPX1 Pro198Leu polymorphism, interactions with smoking and alcohol consumption, and risk for lung cancer. Cancer Lett. 2007;247:293–300. doi: 10.1016/j.canlet.2006.05.006. [DOI] [PubMed] [Google Scholar]
- 10.Arsova-Sarafinovska Z, Matevska N, Eken A, Petrovski D, Banev S, Dzikova S, Georgiev V, Sikole A, Erdem O, Sayal A, Aydin A, Dimovski AJ. 10 glutathione peroxidase 1 (GPX1) genetic polymorphism, erythrocyte GPX activity, and prostate cancer risk. Int Urol Nephrol. 2009;41:63–70. doi: 10.1007/s11255-008-9407-y. [DOI] [PubMed] [Google Scholar]
- 11.Hansen RD, Krath BN, Frederiksen K, Tjonneland A, Overvad K, Roswall N, Loft S, Dragsted LO, Vogel U, Raaschou-Nielsen O. GPX1 Pro(198)Leu polymorphism, erythrocyte GPX activity, interaction with alcohol consumption and smoking, and risk of colorectal cancer. Mutat Res. 2009;664:13–19. doi: 10.1016/j.mrfmmm.2009.01.009. [DOI] [PubMed] [Google Scholar]
- 12.DerSimonian R, Kacker R. Random-effects model for meta-analysis of clinical trials: an update. Contemp Clin Trials. 2007;28:105–114. doi: 10.1016/j.cct.2006.04.004. [DOI] [PubMed] [Google Scholar]
- 13.Mantel N, Haenszel W. Statistical aspects of the analysis of data from retrospective studies of disease. J Natl Cancer Inst. 1959;22:719–748. [PubMed] [Google Scholar]
- 14.Abe M, Xie W, Regan MM, King IB, Stampfer MJ, Kantoff PW, Oh WK, Chan JM. Singlenucleotide polymorphisms within the antioxidant defence system and associations with aggressive prostate cancer. BJU Int. 2011;107:126–134. doi: 10.1111/j.1464-410X.2010.09344.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 15.Ahn J, Gammon MD, Santella RM, Gaudet MM, Britton JA, Teitelbaum SL, Terry MB, Neugut AI, Ambrosone CB. No association between glutathione peroxidase Pro198Leu polymorphism and breast cancer risk. Cancer Epidemiol Biomarkers Prev. 2005;14:2459–2461. doi: 10.1158/1055-9965.EPI-05-0459. [DOI] [PubMed] [Google Scholar]
- 16.Aynali G, Dogan M, Sutcu R, Yuksel O, Yariktas M, Unal F, Yasan H, Ceyhan B, Tuz M. Polymorphic variants of MnSOD Val16Ala, CAT-262 C < T and GPx1 Pro198Leu genotypes and the risk of laryngeal cancer in a smoking population. J Laryngol Otol. 2013;127:997–1000. doi: 10.1017/S0022215113002028. [DOI] [PubMed] [Google Scholar]
- 17.Banescu C, Trifa AP, Voidazan S, Moldovan VG, Macarie I, Benedek Lazar E, Dima D, Duicu C, Dobreanu M. CAT, GPX1, MnSOD, GSTM1, GSTT1, and GSTP1 genetic polymorphisms in chronic myeloid leukemia: a case-control study. Oxid Med Cell Longev. 2014;2014:875861. doi: 10.1155/2014/875861. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 18.Banescu C, Iancu M, Trifa AP, Candea M, Benedek Lazar E, Moldovan VG, Duicu C, Tripon F, Crauciuc A, Dobreanu M. From six gene polymorphisms of the antioxidant system, only GPX Pro198Leu and GSTP1 Ile105Val modulate the risk of acute myeloid leukemia. Oxid Med Cell Longev. 2016;2016:2536705. doi: 10.1155/2016/2536705. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 19.Bhatti P, Stewart PA, Hutchinson A, Rothman N, Linet MS, Inskip PD, Rajaraman P. Lead exposure, polymorphisms in genes related to oxidative stress, and risk of adult brain tumors. Cancer Epidemiol Biomarkers Prev. 2009;18:1841–1848. doi: 10.1158/1055-9965.EPI-09-0197. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 20.Cebrian A, Pharoah PD, Ahmed S, Smith PL, Luccarini C, Luben R, Redman K, Munday H, Easton DF, Dunning AM, Ponder BA. Tagging single-nucleotide polymorphisms in antioxidant defense enzymes and susceptibility to breast cancer. Cancer Res. 2006;66:1225–1233. doi: 10.1158/0008-5472.CAN-05-1857. [DOI] [PubMed] [Google Scholar]
- 21.Cheng TY, Barnett MJ, Kristal AR, Ambrosone CB, King IB, Thornquist MD, Goodman GE, Neuhouser ML. Genetic variation in myeloperoxidase modifies the association of serum alpha-tocopherol with aggressive prostate cancer among current smokers. J Nutr. 2011;141:1731–1737. doi: 10.3945/jn.111.141713. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 22.Choi JY, Neuhouser ML, Barnett M, Hudson M, Kristal AR, Thornquist M, King IB, Goodman GE, Ambrosone CB. Polymorphisms in oxidative stress-related genes are not associated with prostate cancer risk in heavy smokers. Cancer Epidemiol Biomarkers Prev. 2007;16:1115–1120. doi: 10.1158/1055-9965.EPI-07-0040. [DOI] [PubMed] [Google Scholar]
- 23.Cox DG, Hankinson SE, Kraft P, Hunter DJ. No association between GPX1 Pro198Leu and breast cancer risk. Cancer Epidemiol Biomarkers Prev. 2004;13:1821–1822. [PubMed] [Google Scholar]
- 24.Erdem O, Eken A, Akay C, Arsova-Sarafinovska Z, Matevska N, Suturkova L, Erten K, Ozgok Y, Dimovski A, Sayal A, Aydin A. Association of GPX1 polymorphism, GPX activity and prostate cancer risk. Hum Exp Toxicol. 2012;31:24–31. doi: 10.1177/0960327111411499. [DOI] [PubMed] [Google Scholar]
- 25.Ermolenko NA, Boiarskikh UA, Sushko AG, Voronina EN, Selezneva IA, Sinkina TV, Lazarev AF, Petrova VD, Filipenko ML. [Effect of point substitutions in the MnSOD, GPX1, and GSTP1 genes on the risk of familial and sporadic breast cancers in residents of the altai region of the russian federation] . Genetika. 2010;46:1685–1691. [PubMed] [Google Scholar]
- 26.Ezzikouri S, El Feydi AE, Afifi R, Benazzouz M, Hassar M, Pineau P, Benjelloun S. Polymorphisms in antioxidant defence genes and susceptibility to hepatocellular carcinoma in a Moroccan population. Free Radic Res. 2010;44:208–216. doi: 10.3109/10715760903402906. [DOI] [PubMed] [Google Scholar]
- 27.Goerlitz D, El Daly M, Abdel-Hamid M, Saleh DA, Goldman L, El Kafrawy S, Hifnawy T, Ezzat S, Abdel-Aziz MA, Zaghloul MS, Ali SR, Khaled H, Amr S, Zheng YL, Mikhail N, Loffredo C. GSTM1, GSTT1 null variants, and GPX1 single nucleotide polymorphism are not associated with bladder cancer risk in Egypt. Cancer Epidemiol Biomarkers Prev. 2011;20:1552–1554. doi: 10.1158/1055-9965.EPI-10-1306. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 28.Hansen R, Saebo M, Skjelbred CF, Nexo BA, Hagen PC, Bock G, Bowitz Lothe IM, Johnson E, Aase S, Hansteen IL, Vogel U, Kure EH. GPX Pro198Leu and OGG1 Ser326Cys polymorphisms and risk of development of colorectal adenomas and colorectal cancer. Cancer Lett. 2005;229:85–91. doi: 10.1016/j.canlet.2005.04.019. [DOI] [PubMed] [Google Scholar]
- 29.He C, Qureshi AA, Han J. Polymorphisms in genes involved in oxidative stress and their interactions with lifestyle factors on skin cancer risk. J Dermatol Sci. 2010;60:54–56. doi: 10.1016/j.jdermsci.2010.07.003. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 30.Hu YJ, Dolan ME, Bae R, Yee H, Roy M, Glickman R, Kiremidjian-Schumacher L, Diamond AM. Allelic loss at the GPx-1 locus in cancer of the head and neck. Biol Trace Elem Res. 2004;101:97–106. doi: 10.1385/BTER:101:2:097. [DOI] [PubMed] [Google Scholar]
- 31.Hu Y, Benya RV, Carroll RE, Diamond AM. Allelic loss of the gene for the GPX1 seleniumcontaining protein is a common event in cancer. J Nutr. 2005;135:3021S–3024S. doi: 10.1093/jn/135.12.3021S. [DOI] [PubMed] [Google Scholar]
- 32.Ichimura Y, Habuchi T, Tsuchiya N, Wang L, Oyama C, Sato K, Nishiyama H, Ogawa O, Kato T. Increased risk of bladder cancer associated with a glutathione peroxidase 1 codon 198 variant. J Urol. 2004;172:728–732. doi: 10.1097/01.ju.0000130942.40597.9d. [DOI] [PubMed] [Google Scholar]
- 33.Jablonska E, Gromadzinska J, Peplonska B, Fendler W, Reszka E, Krol MB, Wieczorek E, Bukowska A, Gresner P, Galicki M, Zambrano Quispe O, Morawiec Z, Wasowicz W. Lipid peroxidation and glutathione peroxidase activity relationship in breast cancer depends on functional polymorphism of GPX1. BMC Cancer. 2015;15:657. doi: 10.1186/s12885-015-1680-4. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 34.Karunasinghe N, Han DY, Goudie M, Zhu S, Bishop K, Wang A, Duan H, Lange K, Ko S, Medhora R, Kan ST, Masters J, Ferguson LR. Prostate disease risk factors among a New Zealand cohort. J Nutrigenet Nutrigenomics. 2012;5:339–351. doi: 10.1159/000346279. [DOI] [PubMed] [Google Scholar]
- 35.Knight JA, Onay UV, Wells S, Li H, Shi EJ, Andrulis IL, Ozcelik H. Genetic variants of GPX1 and SOD2 and breast cancer risk at the ontario site of the breast cancer family registry. Cancer Epidemiol Biomarkers Prev. 2004;13:146–149. doi: 10.1158/1055-9965.epi-03-0164. [DOI] [PubMed] [Google Scholar]
- 36.Kucukgergin C, Gokpinar M, Sanli O, Tefik T, Oktar T, Seckin S. Association between genetic variants in glutathione peroxidase 1 (GPx1) gene, GPx activity and the risk of prostate cancer. Minerva Urol Nefrol. 2011;63:183–190. [PubMed] [Google Scholar]
- 37.Kucukgergin C, Sanli O, Amasyali AS, Tefik T, Seckin S. Genetic variants of MnSOD and GPX1 and susceptibility to bladder cancer in a Turkish population. Med Oncol. 2012;29:1928–1934. doi: 10.1007/s12032-011-0057-z. [DOI] [PubMed] [Google Scholar]
- 38.Lan Q, Zheng T, Shen M, Zhang Y, Wang SS, Zahm SH, Holford TR, Leaderer B, Boyle P, Chanock S. Genetic polymorphisms in the oxidative stress pathway and susceptibility to non-Hodgkin lymphoma. Hum Genet. 2007;121:161–168. doi: 10.1007/s00439-006-0288-9. [DOI] [PubMed] [Google Scholar]
- 39.Lee CH, Lee KY, Choe KH, Hong YC, Noh SI, Eom SY, Ko YJ, Zhang YW, Yim DH, Kang JW, Kim H, Kim YD. [Effects of oxidative DNA damage and genetic polymorphism of the glutathione peroxidase 1 (GPX1) and 8-oxoguanine glycosylase 1 (hOGG1) on lung cancer] . J Prev Med Public Health. 2006;39:130–134. [PubMed] [Google Scholar]
- 40.Lightfoot TJ, Skibola CF, Smith AG, Forrest MS, Adamson PJ, Morgan GJ, Bracci PM, Roman E, Smith MT, Holly EA. Polymorphisms in the oxidative stress genes, superoxide dismutase, glutathione peroxidase and catalase and risk of non-Hodgkin’s lymphoma. Haematologica. 2006;91:1222–1227. [PubMed] [Google Scholar]
- 41.Meplan C, Dragsted LO, Ravn-Haren G, Tjonneland A, Vogel U, Hesketh J. Association between polymorphisms in glutathione peroxidase and selenoprotein P genes, glutathione peroxidase activity, HRT use and breast cancer risk. PLoS One. 2013;8:e73316. doi: 10.1371/journal.pone.0073316. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 42.Meplan C, Hughes DJ, Pardini B, Naccarati A, Soucek P, Vodickova L, Hlavata I, Vrana D, Vodicka P, Hesketh JE. Genetic variants in selenoprotein genes increase risk of colorectal cancer. Carcinogenesis. 2010;31:1074–1079. doi: 10.1093/carcin/bgq076. [DOI] [PubMed] [Google Scholar]
- 43.Oskina NA, capital Ie CNA, Boyarskih UA, Lazarev A, Petrova VD, Ganov DI, Tonacheva OG, Lifschitz GI, Filipenko ML. Associations between SNPs within antioxidant genes and the risk of prostate cancer in the Siberian region of Russia. Pathol Oncol Res. 2014;20:635–640. doi: 10.1007/s12253-014-9742-5. [DOI] [PubMed] [Google Scholar]
- 44.Parlaktas BS, Atilgan D, Gencten Y, Benli I, Ozyurt H, Uluocak N, Erdemir F. A pilot study of the association of manganese superoxide dismutase and glutathione peroxidase 1 single gene polymorphisms with prostate cancer and serum prostate specific antigen levels. Arch Med Sci. 2015;11:994–1000. doi: 10.5114/aoms.2015.54853. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 45.Paz-y-Mino C, Munoz MJ, Lopez-Cortes A, Cabrera A, Palacios A, Castro B, Paz-y-Mino N, Sanchez ME. Frequency of polymorphisms pro198leu in GPX-1 gene and ile58thr in MnSOD gene in the altitude Ecuadorian population with bladder cancer. Oncol Res. 2010;18:395–400. doi: 10.3727/096504010x12644422320780. [DOI] [PubMed] [Google Scholar]
- 46.Peters U, Chatterjee N, Hayes RB, Schoen RE, Wang Y, Chanock SJ, Foster CB. Variation in the selenoenzyme genes and risk of advanced distal colorectal adenoma. Cancer Epidemiol Biomarkers Prev. 2008;17:1144–1154. doi: 10.1158/1055-9965.EPI-07-2947. [DOI] [PubMed] [Google Scholar]
- 47.Rajaraman P, Hutchinson A, Rothman N, Black PM, Fine HA, Loeffler JS, Selker RG, Shapiro WR, Linet MS, Inskip PD. Oxidative response gene polymorphisms and risk of adult brain tumors. Neuro Oncol. 2008;10:709–715. doi: 10.1215/15228517-2008-037. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 48.Ratnasinghe D, Tangrea JA, Andersen MR, Barrett MJ, Virtamo J, Taylor PR, Albanes D. Glutathione peroxidase codon 198 polymorphism variant increases lung cancer risk. Cancer Res. 2000;60:6381–6383. [PubMed] [Google Scholar]
- 49.Reszka E, Gromadzinska J, Jablonska E, Wasowicz W, Jablonowski Z, Sosnowski M. Level of selenoprotein transcripts in peripheral leukocytes of patients with bladder cancer and healthy individuals. Clin Chem Lab Med. 2009;47:1125–1132. doi: 10.1515/CCLM.2009.261. [DOI] [PubMed] [Google Scholar]
- 50.Rosenberger A, Illig T, Korb K, Klopp N, Zietemann V, Wolke G, Meese E, Sybrecht G, Kronenberg F, Cebulla M, Degen M, Drings P, Groschel A, Konietzko N, Kreymborg KG, Haussinger K, Hoffken G, Jilge B, Ko YD, Morr H, Schmidt C, Schmidt EW, Tauscher D, Bickeboller H, Wichmann HE. Do genetic factors protect for early onset lung cancer? A case control study before the age of 50 years. BMC Cancer. 2008;8:60. doi: 10.1186/1471-2407-8-60. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 51.Skuladottir H, Autrup H, Autrup J, Tjoenneland A, Overvad K, Ryberg D, Haugen A, Olsen JH. Polymorphisms in genes involved in xenobiotic metabolism and lung cancer risk under the age of 60 years. A pooled study of lung cancer patients in Denmark and Norway. Lung Cancer. 2005;48:187–199. doi: 10.1016/j.lungcan.2004.10.013. [DOI] [PubMed] [Google Scholar]
- 52.Steinbrecher A, Meplan C, Hesketh J, Schomburg L, Endermann T, Jansen E, Akesson B, Rohrmann S, Linseisen J. Effects of selenium status and polymorphisms in selenoprotein genes on prostate cancer risk in a prospective study of European men. Cancer Epidemiol Biomarkers Prev. 2010;19:2958–2968. doi: 10.1158/1055-9965.EPI-10-0364. [DOI] [PubMed] [Google Scholar]
- 53.Su S, He K, Li J, Wu J, Zhang M, Feng C, Xia X, Li B. Genetic polymorphisms in antioxidant enzyme genes and susceptibility to hepatocellular carcinoma in Chinese population: a case-control study. Tumour Biol. 2015;36:4627–4632. doi: 10.1007/s13277-015-3110-2. [DOI] [PubMed] [Google Scholar]
- 54.Tang H, Dong X, Day RS, Hassan MM, Li D. Antioxidant genes, diabetes and dietary antioxidants in association with risk of pancreatic cancer. Carcinogenesis. 2010;31:607–613. doi: 10.1093/carcin/bgp310. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 55.Tsai SM, Wu SH, Hou MF, Chen YL, Ma H, Tsai LY. Oxidative stress-related enzyme gene polymorphisms and susceptibility to breast cancer in non-smoking, non-alcohol-consuming Taiwanese women: a case-control study. Ann Clin Biochem. 2012;49:152–158. doi: 10.1258/acb.2011.011098. [DOI] [PubMed] [Google Scholar]
- 56.Vogel U, Olsen A, Wallin H, Overvad K, Tjonneland A, Nexo BA. No association between GPX Pro198Leu and risk of basal cell carcinoma. Cancer Epidemiol Biomarkers Prev. 2004;13:1412–1413. [PubMed] [Google Scholar]
- 57.Wang J, Sun T, Yang M, Lin DX, Tan W, Li KJ, Xiao Y. [Association of genetic polymorphisms in selenoprotein GPX1 and TXNRD2 with genetic susceptibility of gastric cancer] . Zhonghua Yu Fang Yi Xue Za Zhi. 2008;42:511–514. [PubMed] [Google Scholar]
- 58.Wang SS, Davis S, Cerhan JR, Hartge P, Severson RK, Cozen W, Lan Q, Welch R, Chanock SJ, Rothman N. Polymorphisms in oxidative stress genes and risk for non-Hodgkin lymphoma. Carcinogenesis. 2006;27:1828–1834. doi: 10.1093/carcin/bgl013. [DOI] [PubMed] [Google Scholar]
- 59.Wu SH, Lee KW, Chen CH, Lin CC, Tseng YM, Ma H, Tsai SM, Tsai LY. Epistasis of oxidative stress-related enzyme genes on modulating the risks in oral cavity cancer. Clin Chim Acta. 2010;411:1705–1710. doi: 10.1016/j.cca.2010.07.007. [DOI] [PubMed] [Google Scholar]
- 60.Brigelius-Flohe R, Kipp A. Glutathione peroxidases in different stages of carcinogenesis. Biochim Biophys Acta. 2009;1790:1555–1568. doi: 10.1016/j.bbagen.2009.03.006. [DOI] [PubMed] [Google Scholar]
