An updated meta-analysis on the association of MDM2 SNP309 polymorphism with colorectal cancer risk

Association between DPP6 gene rs10260404 polymorphism and increased risk of sporadic amyotrophic lateral sclerosis (sALS): a meta-analysis

BACKGROUND

Sporadic amyotrophic lateral sclerosis (sALS) is a severe neurodegenerative disease characterized by continuous diminution of motor neurons in the brain and spinal cord. Earlier studies indicated that the DPP6 gene variant has a role in the development of sALS. This meta-analysis was designed to uncover the role of rs10260404 polymorphism of the DPP6 gene and its association with sALS.

METHODS

All case-control articles published prior to October 2022 on the association between DPP6 (rs10260404) polymorphism and sALS risk were systematically extracted from different databases which include PubMed, PubMed Central, and Google Scholar. Overall odds ratios (ORs) and "95% confidence intervals (CIs)" were summarized for various genetic models. Subgroup and heterogeneity assessments were performed. Egger's and "Begg's tests were applied to evaluate publication bias. Trial sequential analysis (TSA) and false-positive report probability (FPRP) were performed.

RESULTS

Nine case-control studies containing 4202 sALS cases and 4444 healthy controls were included in the meta-analysis. A significant association of the DPP6 (rs10260404) variant with an increased sALS risk in overall pooled subjects under allelic model [C allele vs. T allele, OR = 1.149, 95% CI (1.010-1.307), p-value = 0.035], dominant model [CC + CT vs. TT, OR = 1.165, 95% CI (1.067-1.273), p-value = 0.001], and homozygote comparison [CC vs. TT, OR = 1.421, 95% CI (1.003-2.011), p-value = 0.048] were observed. Moreover, in subgroup analysis by nationality, remarkable associations were detected in Dutch, Irish, American, and Swedish under allelic, dominant, and homozygote models. Additionally, stratification analysis by ethnicity exhibited an association with sALS risk among Caucasians and Americans under different genetic models. Interestingly, none of the models found any significant association with Asians.

CONCLUSION

The present meta-analysis indicates that DPP6 (rs10260404) polymorphism could be a candidate risk factor for sALS predisposition.

Association of Murine Double Minute 2 polymorphisms with gastric cancer: A systematic review with meta-analysis

Gastric cancer (GC) is the 5th most common type of cancer, with the 3rd highest mortality rate worldwide in both sexes. Murine double minute 2 (MDM2) protein is the major negative regulator of p53, and genetic polymorphisms in this gene have shown to be associated with several types of cancer. In the present study, a literature search was performed using PubMed and Scopus with the following key word combinations 'gastric cancer AND polymorphism AND MDM2'. Studies were carefully revised according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines to identify eligible studies that matched the inclusion criteria. Statistical analysis was performed to assess the association between the different genetic polymorphisms and GC risk, by calculating the odds ratios (OR) and the confidence intervals (CI), with a 5% level of significance. A total of 11 manuscripts studied MDM2 polymorphisms in GC: rs937283 (n=1), rs3730485 (n=1) and rs2279744 (n=9). Both the rs937283 and rs3730485 reports showed an association with GC; however, there was only one study on each of these polymorphisms in the literature. A meta-analysis was performed for the rs2279744 polymorphism, of which studies showed a positive association between the G allele and risk of GC, either in the dominant model (OR=1.46; 95% CI 1.21-1.75; P<0.001) or recessive model (OR 1.65; 95% CI 1.45-1.87; P<0.001). In conclusion, genetic polymorphisms in MDM2 seemed to be associated with an increased risk of GC development, nevertheless, the number of studies were relatively low and the studied populations were primarily Chinese. The present meta-analysis emphasizes the need for additional studies in other populations to corroborate the association of these polymorphisms with GC.

The cell cycle regulatory gene polymorphisms TP53 (rs1042522) and MDM2 (rs2279744) in lung cancer: a meta-analysis

Lung cancer is one of the most common types of cancer in the world. Although the mechanism of lung cancer is still unknown, a large number of studies have found a link between gene polymorphisms and the risk of lung cancer. The tumor suppressor p53 plays a crucial role in maintaining genomic stability and tumor prevention. MDM2 is a critical regulator of the p53 protein. Despite the importance of p53 pathway in cancer, data on the contribution of SNPs of TP53 (rs1042522) and MDM2 (rs2279744) to the development of lung cancer are very contradictory. A metaanalysis that collects quantitative data from individual studies and combines their results has the advantage of improving accuracy, providing reliable estimates, and resolving those issues in which studies on individual associations are not effective enough. The aim of this study was to determine whether the TP53 (rs1042522) and MDM2 (rs2279744) polymorphisms confer susceptibility to lung cancer. A meta-analysis was conducted on the associations between the TP53 (rs1042522) and MDM2 (rs2279744) polymorphisms and lung cancer. A total of 51 comparison studies including 25,366 patients and 25,239 controls were considered in this meta-analysis. The meta-analysis showed no association between lung cancer and MDM2 (rs2279744) under any model. A noteworthy association of TP53 (rs1042522) with susceptibility to lung cancer in overall pooled subjects was observed under three different models (allele contrast, homozygote contrast (additive) and dominant). Stratification by ethnicity indicated an association between the TP53 (rs1042522) and lung cancer in Asians and Caucasians. This meta-analysis demonstrates that the TP53 (rs1042522), but not MDM2 (rs2279744) polymorphism may confer susceptibility to lung cancer.

Genetic polymorphisms of TP53 (rs1042522) and MDM2 (rs2279744) and colorectal cancer risk: An updated meta-analysis based on 59 case-control studies

OBJECTIVE

Several earlier reports implicated TP53 (rs1042522) and MDM2 (rs2279744) variants in outcome of colorectal cancer (CRC), but with inconclusive findings. This current meta-analysis designed to uncover the role of these variants in CRC risk.

METHODOLOGY

Two independent investigators extracted 59 eligible case-control studies from different electronic databases involving Scopus, Web of Science and PubMed prior to June 2019. Pooled odds ratios (ORs) and "95% confidence intervals (CIs)" were computed for different hereditary models. Stratification and heterogeneity analyses, and "Begg's funnel plots" were conducted. In silico data analyses of the functional and structural properties of the study variants were applied.

RESULTS

In general, 47 and 16 case-control reports for TP53 (11,589 patients and 13,622 controls) and MDM2 (6841 CRC patients and 8792 healthy controls), respectively were enrolled in this meta-analysis. A significant association of TP53 (rs1042522) variant with increased CRC risk in overall pooled subjects under recessive model [(CC vs. GC + GG, OR = 1.134, 95% CI = 1.006-1.278, P = 0.039)] was observed. Moreover, an evidence of MDM2 (rs2279744) association with increased CRC risk in overall pooled subjects under dominant and heterozygote models [(TG + GG vs. TT, OR = 1.120, 95% CI = 1.003-1.250, P = 0.044) and (TG vs. TT, OR = 1.189, 95% CI = 1.076-1.313, P = 0.001), respectively] was reported. Additionally, TP53 (rs1042522) and MDM2 (rs2279744) showed an association with CRC risk among Asians and Africans under a recessive model, and among Asians under different genetic models, respectively, by stratification analysis.

CONCLUSION

TP53 (rs1042522) and MDM2 (rs2279744) variants might represent candidate risk factors for CRC susceptibility.

Role of screening colonoscopy for colorectal tumors in Helicobacter pylori-related chronic gastritis with MDM2 SNP309 G/G homozygous: A prospective cross-sectional study in Thailand

BACKGROUND/AIMS

Helicobacter pylori infection is a risk factor for gastric cancer and colorectal cancer (CRC). MDM2 SNP309 G/G homozygosity is known to be the genetic background that influences the severity of inflammation in the gastric mucosa, and it corresponds to CRC development. We examined the role of screening colonoscopy in H. pylori-related chronic gastritis and the association of patients who have MDM2 SNP309 G/G homozygosity and advanced colorectal neoplasia (CRN) susceptibility.

MATERIALS AND METHODS

A prospective cross-sectional study was used to investigate H. pylori-related gastritis in 331 consecutive asymptomatic patients who had MDM2 SNP309 G/G homozygosity and who were enrolled from November 2014 to July 2017. The MDM2 SNP309 polymorphism was genotyped by real-time PCR hybridization probe assay.

RESULTS

Totally, there were 331 patients with H. pylori-related gastritis, of whom 39 (8.76%) had advanced CRN. The H. pylori-positive group comprised 180 patients (54.36%). H. pylori infection was associated with advanced CRN (OR: 2.09, 95% CI: 1.56-2.80; p=0.01) and had an increased risk of advanced CRN (OR: 4.24, 95% CI: 1.76-5.21; p=0.01) after adjusting for confounding factors. Patients with H. pylori infection had a significantly increased risk of high-grade dysplasia or invasive adenocarcinoma (OR: 2.96, 95% CI: 1.48-4.17; p=0.03).

CONCLUSION

Chronic gastritis patients infected with H. pylori and who had MDM2 SNP309 G/G homozygosity had an increased risk of advanced CRN, particularly high-grade dysplasia including invasive adenocarcinoma. Screening colonoscopy in these patients might benefit colorectal polyp diagnosis and prevention and early CRC treatment in the Thai population.

Genetic polymorphisms of IL-17A rs2275913, rs3748067 and IL-17F rs763780 in gastric cancer risk: evidence from 8124 cases and 9873 controls

Interleukin-17 (IL-17) is a critical cytokine involved in inflammation-associated cancers. Single nucleotide polymorphisms (SNPs) might promote carcinogenesis. In this current meta-analysis, we investigated the association of IL-17A and IL-17F gene polymorphisms with gastric cancer (GC) risk. Eligible genetic association studies were retrieved from PubMed, Web of Science and Scopus database sources. Two reviewers independently assessed methodological quality and extracted data from eligible articles. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were calculated. Quantitative data synthesis was conducted using comprehensive meta-analysis v2. Subgroup analysis and heterogeneity analysis were performed. Begg's funnel plot and Egger's regression tests were used to judge publication bias. In silico data analysis was executed to analyze the functional and structural impact of the SNPs. A total of 21 case-control studies for rs2275913 c.-197G > A (7660 patients and 9409 controls), 9 studies for rs3748067 c.*1249C > T (3378 patients and 4120 controls), and 14 studies for rs763780 c.482A > G (4481 patients and 5354 controls) were included. The pooled estimate revealed an association between IL-17A rs2275913 polymorphism and the risk of GC under all genetic models (A vs. G, OR 1.187, 95% CI 1.086-1.297, P < 0.001; GA vs. GG, OR 1.108, 95% CI 1.008-1.218, P = 0.033; AA vs. GG, OR 1.484, 95% CI 1.236-1.781, P < 0.001), while no evidence of association was found with IL-17A rs3748067 or IL-17F rs763780 polymorphisms. Our results showed that IL-17A promoter rs2275913 variant might represent a potential risk factor for gastric cancer susceptibility.

Genetic polymorphism in the asporin gene is not a key risk factor for osteoarthritis: Evidence based on an updated cumulative meta-analysis

To provide an evidence-based medical basis for the treatment of osteoarthritis, a meta-analysis was performed to assess the association between asporin (ASPN) gene polymorphism and susceptibility to osteoarthritis (OA). The current study searched the literature from January 1st, 1915 through February 1st, 2017 using the Cochrane Library, PubMed, the Excerpta Medica database (EMBASE) and three main Chinese databases (VIP, CNKI and Wan Fang). Cohort and case-control studies that explored the association between different types of ASPN alleles and OA susceptibility were evaluated. The K/L grading system, clinical and radiological diagnoses were used for OA diagnosis. A random-effects model was used in a pooled analysis to adjust for heterogeneity of the included studies, and the differences between treatment groups were reported as odds ratio (OR), 95% confidence intervals (CIs) and P-values. Begg's funnel plots and Egger's tests were used to assess publication bias in the present meta-analysis. Following document retrieval and screening, a total of 10 studies were deemed eligible, including 4,842 patients and 3,661 healthy subjects. Results of the multivariate meta-regression analysis revealed that the study sample size was a source of heterogeneity between studies. The D17 allele was a risk factor for the development of OA (OR=1.33, 95% CI: 1.02–1.73, P<0.05). The other alleles were not considered as risk factors for development of OA (P>0.05). The results of the meta-analysis verified that ASPN polymorphisms were not significantly relevant to an increased OA risk. However, the mechanisms contributing to the association between ASPN polymorphisms and OA risk still require further study.

Low penetrance genetic polymorphisms as potential biomarkers for colorectal cancer predisposition

Colorectal cancer is a leading form of cancer in both males and females. Early detection of individuals at risk of colorectal cancer allows proper treatment and management of the disease to be implemented, which can potentially reduce the burden of colorectal cancer incidence, morbidity and mortality. In recent years, the role of genetic susceptibility factors in mediating predisposition to colorectal cancer has become more and more apparent. Identification of high-frequency, low-penetrance genetic polymorphisms associated with the cancer has therefore emerged as an important approach which can potentially aid prediction of colorectal cancer risk. However, the overwhelming amount of genetic epidemiology data generated over the past decades has made it difficult for one to assimilate the information and determine the exact genetic polymorphisms that can potentially be used as biomarkers for colorectal cancer. This review comprehensively consolidates, based primarily on results from meta-analyses, the recent progresses in the search of colorectal cancer-associated genetic polymorphisms, and discusses the possible mechanisms involved.

Genetic Modifiers of the p53 Pathway

The tumor suppressor gene TP53 is the most frequently mutated gene in human cancer; this gene is subject to inactivation by mutation or deletion in >50% of sporadic cancers. Genes that encode proteins that regulate p53 function, such as MDM2, MDM4, and CDKN2A (p14(ARF)) are also frequently altered in tumors, and it is generally believed that the p53 pathway is likely to be inactivated by mutation in close to 100% of human tumors. Unlike most other cancer-relevant signaling pathways, some of the genes in the p53 pathway contain functionally significant single nucleotide polymorphisms (SNPs) that alter the amplitude of signaling by this protein. These variants, thus, have the potential to impact cancer risk, progression, and the efficacy of radiation and chemotherapy. In addition, the p53 pathway plays a role in other biological processes, including metabolism and reproductive fitness, so these variants have the potential to modify other diseases as well. Here we have chosen five polymorphisms in three genes in the p53 pathway for review, two in TP53, two in MDM2, and one in MDM4. These five variants were selected based on the quality and reproducibility of functional data associated with them, as well as the convincingness of epidemiological data in support of their association with disease. We also highlight two other polymorphisms that may affect p53 signaling, but for which functional or association data are still forthcoming (KITLG and ANRIL). Finally, we touch on three questions regarding genetic modifiers of the p53 pathway: Why did these variants arise? Were they under selection pressure? And, is there compelling evidence to support genotyping these variants to better predict disease risk and prognosis?

Association between MDM2 SNP309 T>G polymorphism and the risk of bladder cancer: new data in a Chinese population and an updated meta-analysis

Objective

Human murine double minute 2 protein (MDM2) is mainly a negative regulator of p53 tumor suppressor pathway. We aimed to investigate the association between MDM2 SNP309 polymorphism and bladder cancer risk.

Methods

A total of 535 bladder cancer patients and 649 health controls were recruited for our study. MDM2 SNP309 T>G polymorphism was genotyped by polymerase chain reaction-ligase detection reaction method. Logistic regression was used to analyze the relationship between the genotype and susceptibility of bladder cancer. Kaplan–Meier estimates and log-rank test were obtained to analyze the association between the genotype and risk of recrudesce in nonmuscle-invasive bladder cancer patients. A multivariable Cox proportional hazards model was fitted to identify independent prognostic factors. To further investigate the association, we conducted a meta-analysis including six studies.

Results

The frequency of the MDM2 SNP309 T>G polymorphism showed no significant difference between cases and controls (all P>0.05). In the stratification analysis, the results showed that G allele carriers were prone to have a significant decrease in risk of low-grade bladder cancer (adjusted odds ratio: 0.613, 95% confidence interval: 0.427–0.881), and G variant was associated with a significantly reduced risk of recurrence in nonmuscle-invasive bladder cancer patients with or without chemotherapy (P<0.05). The results of the meta-analysis showed that G allele and GG genotype of MDM2 SNP309 polymorphism were significantly associated with increased risk of bladder cancer in Caucasians (both P<0.05), and no association was observed in total populations and Asians (P>0.05).

Conclusion

MDM2 SNP309 T>G polymorphism has no influence on bladder cancer risk in Asians, but this single nucleotide polymorphism may be associated with genetic susceptibility of bladder cancer among Caucasians.

Association of the recurrence of vocal leukoplakia with MDM2-309 variants over a 2-year period: a prospective study

CONCLUSION

MDM2-309 polymorphism variant genotypes decrease the risk of recurrence in vocal leukoplakia.

OBJECTIVE

The results of a previous study 2 years ago showed the effect of mouse double minute 2 homolog (MDM2) SNP309 polymorphisms in people with laryngeal carcinoma and vocal leukoplakia (a pre-cancerous laryngeal carcinoma lesion). This prospective, clinical trial was performed to assess the relationship between MDM2-309 polymorphism variants and recurrence/cancerization rates in people with vocal leukoplakia over a 2-year period.

PARTICIPANTS AND METHOD

A total of 61 post-operative patients with vocal leukoplakia participated in this prospective, observational, 2-year, follow-up study, and were genotyped for the MDM2-309 gene using pyrosequencing. Recurrence and cancerization rates were used to assess the relationship between the clinical outcome and the genotype variants.

RESULTS

The recurrence rate in the GT genotypes group was lower than that in the normal TT genotype group (17.2% vs 50%, p = 0.05) and there was a significantly lower recurrence rate in the GG genotype group than in the normal TT genotype group (10% vs 50%, p = 0.03). However, there was no statistically significant difference in the cancerization rate between the MDM2-309 variant (GT + GG) genotypes group and the normal TT genotype group (12.2% vs 8.3%, p > 0.05) over the 2-year follow-up period.

The RTEL1 rs6010620 polymorphism and glioma risk: a meta-analysis based on 12 case-control studies

BACKGROUND

The association between the RTEL1 rs6010620 single nucleotide polymorphism (SNP) and glioma risk has been extensively studied. However, the results remain inconclusive. To further examine this association, we performed a meta-analysis.

MATERIALS AND METHODS

A computerized search of the PubMed and Embase databases for publications regarding the RTEL1 rs6010620 polymorphism and glioma cancer risk was performed. Genotype data were analyzed in a meta-analysis. Odds ratios (ORs) with 95% confidence intervals (CIs) were estimated to assess the association. Sensitivity analyses, tests of heterogeneity, cumulative meta-analyses, and assessments of bias were performed in our meta-analysis.

RESULTS

Our meta-analysis confirmed that risk with allele A is lower than with allele G for glioma. The A allele of rs6010620 in RTEL1 decreased the risk of developing glioma in the 12 case-control studies for all genetic models: the allele model (OR=0.752, 95%CI: 0.715-0.792), the dominant model (OR=0.729, 95%CI: 0.685-0.776), the recessive model (OR=0.647, 95%CI: 0.569-0.734), the homozygote comparison (OR=0.528, 95%CI: 0.456-0.612), and the heterozygote comparison (OR=0.761, 95%CI: 0.713-0.812).

CONCLUSIONS

In all genetic models, the association between the RTEL1 rs6010620 polymorphism and glioma risk was significant. This meta-analysis suggests that the RTEL1 rs6010620 polymorphism may be a risk factor for glioma. Further functional studies evaluating this polymorphism and glioma risk are warranted.

MDM2 SNP309 variation confers the susceptibility to hepatocellular cancer: a meta-analysis based on 4271 subjects

Previous reports have indicated that MDM2 T309G polymorphism might be a risk factor for various cancers. Increasing studies have been conducted on the association of MDM2 T309G polymorphism with hepatocellular carcinoma (HCC) risk. However, the results remain inconclusive. Thus, the present study aimed to address this controversy by meta-analysis. Relevant literature up to Oct 2014 was searched and screened. Necessary information was rigorously extracted for data pooling and analyzing. Separate analyses on ethnicity, source of controls, sample size and P53 polymorphism status were also performed. As a result, eleven case-control studies were selected and the overall data indicated a significant association of MDM2 T309G polymorphism with HCC risk (GG vs. TT: OR=2.31; 95% CI=1.66-3.20; dominant model: OR=1.83; 95% CI=1.36-2.47; recessive model: OR=1.73; 95% CI=1.49-2.00). Similar results could be shown in the subgroups regarding ethnicity, source of controls and sample size. Interestingly, in the subgroup analysis regarding P53 codon 72 polymorphism, increased HCC risk could be observed in the Pro/Pro+Pro/Arg subgroup under a recessive model (OR=1.78; 95% CI=1.29-2.44). In conclusion, the results of the present study suggest that MDM2 T309G polymorphism might be a low-penetrant risk factor for HCC. Homozygous GG alleles might interact with Pro of P53 and thus confer the susceptibility to HCC.

Impact of the Mdm2(SNP309-G) allele on a murine model of colorectal cancer

A single-nucleotide polymorphism (SNP) in the promoter of the Mdm2 gene (Mdm2(SNP309-G)) results in an increased Mdm2 expression, partial attenuation of the p53 pathway and accelerated tumor development. Clinical case-control studies indicate the Mdm2(SNP309-)(G) allele associates with a significant increase in colorectal cancer (CRC) risk that is heightened in women, but the biological significance of this polymorphism has never been directly evaluated. To examine whether the Mdm2(SNP309-)(G) allele contributes to colorectal cancer, we generated cohorts of mice harboring either the G (minor allelic variant) or T (major allelic variant) allele and treated them with azoxymethane (AOM), a carcinogen that induces sporadic colorectal cancer. Mdm2(SNP309-G/G) mice displayed a significant reduction in survival following AOM treatment with more colonic lesions in a wider distribution throughout the lower and upper colon and an attenuated apoptotic response following exposure. AOM did not significantly induce stabilization of wild-type p53 or activate p53 downstream targets following AOM treatment, regardless of the genotype. Instead, Mdm2(SNP309-G/G) colons had significant changes in the expression of genes that regulate Mdm2 transcription (ERα and Sp1) as well as downstream targets of Mdm2. Together these results suggest the Mdm2(SNP309-)(G) allele significantly impacts CRC through mechanisms outside the p53 pathway.

The T309G murine double minute 2 gene polymorphism is an independent prognostic factor for patients with renal cell carcinoma

The purpose of this study was to evaluate the association of the T309G MDM2 gene polymorphism with renal cell carcinoma (RCC) risk, pathology, and cancer-specific survival (CSS). T309G MDM2 was genotyped in 449 Caucasians, including 240 with RCC and 209 cancer-free controls. The T309G MDM2 genotype was TT in 174 (38.8%), GT in 214 (47.7%), and GG in 61 (13.6%) subjects, without any significant differences between cases and controls on both univariable (p=0.58) and multivariable logistic regression (each p>0.25). Furthermore, T309G MDM2 was not linked with T stage (p=0.75), N stage (p=0.37), M stage (p=0.94), grade (p=0.21), and subtype (p=0.55). There was, however, a statistically significant association of T309G MDM2 with CSS (p=0.022): patients with TT had significantly worse survival than GG/GT (p=0.009), while those with GT and GG had similar outcomes (p=0.92). The 5-year survival rate for patients with TT, GT, and GG was 69.5%, 84.5%, and 89.7%, respectively. On the multivariable analysis, T309G was identified as an independent prognostic factor. The T309G MDM2 polymorphism is an independent prognostic factor for patients with RCC, with the TT genotype being associated with worse prognosis. In this study, there were no significant associations with RCC risk and pathology.

Association between the MDM2 T309G polymorphism and leukemia risk: a meta-analysis

Several studies have suggested associations between MDM2 (mouse double minute 2 homolog) polymorphisms and leukemia risk, but they reported contradictory results. For better understanding of the effect of MDM2 T309G polymorphism on leukemia risk, we performed a meta-analysis. All eligible studies were identified through a search of PubMed, Web of Science, EMBASE, and Chinese Biomedical Literature (CBM) databases before May 2014. Assessment of associations between the MDM2 T309G polymorphism and leukemia risk was conducted by odds ratios (ORs) and 95% confidence intervals (95% CIs). Finally, a total of 11 publications covering 12 case-control studies with 2, 362 cases and 5, 562 controls concerning MDM2 T309G polymorphism with respect to leukemia were included in the meta-analysis. Significant associations were found between MDM2 T309G polymorphism and leukemia risk in four models in overall populations (G vs T: OR=1.29, 95% CI=1.11- 1.49, p=0.001; GG vs TT: OR=1.67, 95% CI=1.21-2.30, p=0.002; GG vs TG/TT: OR=1.56, 95% CI=1.21-2.00, p=0.001; GG/TG vs TT: OR=1.28, 95% CI=1.05-1.57, p=0.015). In the sub-group analysis according to ethnicity, increased leukemia risks were observed in three genetic models among Asians but not Caucasians. In conclusion, the results of our meta-analysis suggest that the MDM2 T309G polymorphism can increase the risk of leukemia, especially among Asian populations.

Current evidence on the relationship between murine double minute 2 T309G polymorphism and esophageal cancer susceptibility

The relationship between murine double minute 2 (MDM2) T309G polymorphism and esophageal cancer risk has been discussed with discrepant results. The aim of our study is to investigate the systematic association between the potentially functional MDM2 T309G polymorphism and esophageal cancer risk. Eligible studies were included through searching the databases of PubMed, EMBASE, and Chinese National Knowledge Infrastructure (up to April 2014). The crude odds ratio (OR) and 95% confidence interval (CI) were used to estimate the strength of the association. Six published case-control studies, including 1899 cases and 3016 controls, were identified. Overall, our study suggested that MDM2 T309G polymorphism was significantly associated with increased risk of esophageal cancer (TT vs. GG: OR = 0.77, 95% CI = 0.65-0.90, P = 0.002; T vs. G: OR = 0.88, 95% CI = 0.81-0.96, P = 0.002). In subgroup analyses stratified by source of controls, ethnicity, and quality score assessment, respectively, similar results were obtained (TT vs. GG: OR = 0.65, 95% CI = 0.48-0.89, P = 0.007 for hospital-based studies; T vs. G: OR = 0.90, 95% CI = 0.81-0.99, P = 0.04 for population-based studies; and T vs. G: OR = 0.85, 95% CI = 0.78-0.93, P = 0.004 for Asians). The results of Begg's test and Egger's test did not suggest publication bias in the studies. Therefore, the MDM2 T309G polymorphism may be significantly associated with increased esophageal cancer risk, especially among Asians.

MDM2 SNP309T>G polymorphism and hepatocellular carcinoma risk: a meta-analysis

Case-control studies on the association between mouse double-minute 2 homolog (MDM2) SNP309T>G polymorphism and hepatocellular carcinoma have provided either controversial or inconclusive results. To clarify the effect of MDM2 SNP309T>G polymorphism on the risk of hepatocellular carcinoma, a meta-analysis of all case-control observational studies was performed. Pooled odds ratios (ORs) for various polymorphisms were estimated using random and fixed effects models. The Q-statistic was used to evaluate the homogeneity, and Egger and Begg tests were used to assess publication bias. Overall, the MDM2 SNP309T>G polymorphism was associated with a risk of hepatocellular carcinoma (OR = 0.68; 95% CI = 0.54-0.85 for allele contrast, p = 0.0005, phet = 0.004). The contrast of homozygotes and the recessive and dominant models produced the same pattern of results as the allele contrast. In the analysis stratified by ethnicity, significant associations were found in the Caucasian population in all of the genetic models. In addition, heterogeneity disappeared in subgroups of Caucasian subjects. Our pooled data suggest evidence for a major role of MDM2 SNP309T>G polymorphism in the carcinogenesis of hepatocellular carcinoma, especially among Caucasian populations.

MDM2 SNP309 is an ethnicity-dependent risk factor for digestive tract cancers

Published data on the relationship between T309G polymorphism in the murine double minute 2 (MDM2) gene and susceptibility of digestive tract cancers (DTC) are inconclusive. Thus, the aim of this study is to determine whether MDM2 T309G polymorphism is associated with the risk of diverse DTC, including esophagus, stomach, liver, bile duct, pancreas, and colorectum cancers. Relevant studies were identified up to October 1, 2013. Crude odds ratio (OR) and 95% confidence interval (CI) were used as a measure of the strength of the association. The pooled result based on all studies showed that there was a statistically significant link between MDM2 T309G polymorphism and DTC susceptibility (T vs. G: OR = 0.82, 95%CI = 0.76-0.88). When stratified by race, significant associations were observed for all genetic models among Asians (especially in Chinese population), but not among Caucasians. Subgroup analyses according to tumor location indicated that the genetic variant was associated with esophageal (OR = 0.88, 95%CI = 0.81-0.96 for T vs. G), hepatocellular (OR = 0.69, 95%CI = 0.57-0.84 for T vs. G) and pancreatic cancer risk but not associated with cholangiocarcinoma or colorectum cancer susceptibility. Meanwhile, the G allele was also suggested to be associated with increased gastric cancer risk (OR = 0.68, 95%CI = 0.54-0.87 for TT + TG vs. GG for intestinal type of gastric cancer and OR = 0.18, 95%CI = 0.06-0.50 for TT vs. GG for Helicobacter pylori infection positive stomach cancer). Our study indicates that the MDM2 T309G polymorphism may be an ethnicity-dependent risk factor for DTC, especially for the upper gastrointestinal tract malignancies.