MDM2 309T>G polymorphism and risk of lung cancer in a Korean population

The MDM2 SNP309 differentially impacts cardiorespiratory fitness in young healthy women and men

PURPOSE

Maximal oxygen consumption (VO2max), the predominant index of cardiorespiratory fitness (CRF), is a predictor of whole-body function and longevity in humans. The central cardiac function and the skeletal muscle's capacity to use oxygen are key determinants of VO2max. Murine Double Minute 2 (MDM2), mainly known as an oncogene, could regulate myocardial hypertrophy, skeletal muscle angiogenesis, and oxidative phosphorylation. A prevalent single nucleotide polymorphism in the MDM2 promoter (SNP309) substitutes a T for a G, supporting a greater transcriptional activity. We aim to assess whether SNP309 impacts intrinsic CRF.

METHODS

82 young healthy nonathletic male and female adults aged 23 ± 2 years performed cardiorespiratory exercise testing to determine their VO2max (mL kg-1 min-1). The genomic DNAs isolated from saliva were genotyped using Taqman-based qPCR.

RESULTS

A one-way ANOVA showed that SNP309 influenced relative VO2max in the whole cohort (p = 0.044) and in men (p = 0.009), remaining non-significant in women (p = 0.133). VO2max was higher in TT homozygotes than in GT heterozygotes (whole cohort, 47 ± 12 vs. 42 ± 6 mL kg-1 min-1, p = 0.030; men, 53 ± 8 vs. 45 ± 6 mL kg-1 min-1, p = 0.011). A contingency analysis revealed a positive association between SNP309 in men in which the TT genotype was more frequent in the high VO2max group (p = 0.006). When considering G as the dominant allele, men bearing a G allele had lower relative VO2max than TT homozygotes (47 ± 7 vs. 53 ± 8, GG/GT vs. TT, p = 0.010). Conversely, women bearing a G allele had a higher relative VO2max than TT homozygotes (39 ± 5 vs. 34 ± 7, GG/GT vs. TT, p = 0.047).

CONCLUSION

SNP309 impacts VO2max in a sex-dependent manner in our cohort.

Interaction between common variants of MDM2 and PPP1R13L and CD3EAP and TP53 SNPs in relation to lung cancer risk among Chinese

Background

Lung cancer is a complex disease that diagnosed the most common cancer and led cause of cancer death. MDM2 (MDM2 proto-oncogene) encodes a nuclear-localized E3 ubiquitin ligase. The encoded protein can promote tumor formation by targeting tumor suppressor proteins, such as TP53, for proteasomal degradation. Epidemiology studies have investigated the association of MDM2 single nucleotide polymorphisms (SNP) and interaction between genetic and environmental factors with lung cancer.

Methods

This Chinese case-control study comprised 627 cases and 633 controls explored the role of MDM2 five htSNPs (rs1690924, rs1846402, rs2291857, rs3730581 and rs3730635, haplotype-tagging SNP) tagging 95% of the common haplotypes across the gene and the interactions of MDM2, PPP1R13L, CD3EAP and TP53 in the same pathological pathway on lung cancer risk, together with smoking-duration.

Results

None of the htSNPs in MDM2 were associated with lung cancer risk in co-dominant, dominant, recessive, and log-additive models (adjusted for smoking-duration). Haplotype analysis showed that global haplotype association was statistically significant (P=0.0036, adjusted for smoking-duration) and haplotype5 (rs1690924^A-rs1846402^G-rs2291857^C-rs3730581^G-rs3730635^A) was associated with reduced risk of lung cancer [OR (95%) =0.52 (0.33–0.82), P=0.0053, adjusted for smoking-duration]. MDR interaction analysis showed that two the best significant models and strong synergy between MDM2 and TP53.

Conclusions

MDM2 five-htSNPs haplotype exhibited association with lung cancer susceptibility, interaction of MDM2 and TP53 htSNPs and smoking-duration contributed to lung cancer risk and strong synergy between MDM2 and TP53 htSNPs influenced lung cancer predisposition. Our results suggest that MDM2, TP53 and smoking-duration interact in relation to lung carcinogenesis.

A cohort study on the association of MDM2 SNP309 with lung cancer risk in Bangladeshi population

BACKGROUND/AIMS

Bangladesh is a densely populated country with an increased incidence of lung cancer, mostly due to smoking. Therefore, elucidating the association of mouse double minute 2 homolog (MDM2) single nucleotide polymorphism (SNP) 309 (rs2279744) with lung cancer risk from smoking in Bangladeshi population has become necessary.

METHODS

DNA was extracted from blood samples of 126 lung cancer patient and 133 healthy controls. The MDM2 SNP309 was genotyped by polymerase chain reaction- restriction fragment length polymorphism (PCR-RFLP), using the restriction enzymes MspA1I. Logistic regression was then carried out to calculate odds ratios (ORs) and 95% confidence intervals (CIs) to estimate the risk of lung cancer. A meta-analysis of SNP309 was also carried out on 12,758 control subjects and 11,638 patient subjects.

RESULTS

In multivariate logistic regression, significantly increased risk of lung cancer was observed for MDM2 SNP309 in the dominant model (TG + GG vs. TT: OR, 2.13; 95% CI, 1.29 to 3.53). Stratification analysis revealed that age, sex, obesity, and smoking also increases the risk of lung cancer when carrying the MDM2 SNP309. Our meta-analysis revealed that MDM2 SNP309 was considerably associated with lung cancer in Asian populations (TG + GG vs. TT: OR, 1.32; 95% CI , 1.12 to 1.56; p = 0.019 for heterogeneity).

CONCLUSION

The MDM2 SNP309 was associated with high risk of lung cancer in Bangladeshi and Asian population, particularly with increased age, smoking, and body mass index.

A comprehensive evaluation of single nucleotide polymorphisms associated with hepatocellular carcinoma risk in Asian populations: A systematic review and network meta-analysis

BACKGROUND

Single nucleotide polymorphisms (SNPs) have been inconsistently associated with hepatocellular carcinoma (HCC) risk. This meta-analysis aimed to synthesize relevant data on SNPs associated with HCC in the Asian population.

METHODS

Databases were searched to identify association studies of SNPs and HCC in Asians published through January 2019. Summary odds ratios (ORs) and 95% confidence intervals (CIs) were calculated based on 41 studies (13,167 patients with HCC and 15,886 noncancer controls). Network meta-analysis and Thakkinstian's algorithm were used to select the most appropriate genetic model, along with false positive report probability (FPRP) for noteworthy associations.

RESULTS

Eleven SNPs meeting the inclusion criteria were tested for association with HCC, including CCND1 rs9344, PTGS2 rs689466, IL18 rs187238 and rs1946518, KIF1B rs17401966, MDM2 rs2279744, MIR146A rs2910164, MIR149 rs2292832, MIR196A2 rs11614913, MIR499A rs3746444, and TGFB1 rs1800469. A significant increase for HCC risk was observed for MDM2 rs2279744, and the dominant (pooled OR = 1.59, 95% CI: 1.26-2.00) and codominant (pooled OR = 1.37, 95% CI: 1.18-1.60) models were determined to be the most appropriate models. MIR499A rs3746444 also showed a significant association with HCC risk under the allele contrast model (pooled OR = 1.36, 95% CI: 1.05-1.77). Only the significance of MDM2 rs2279744 was noteworthy (FPRP < 0.2).

CONCLUSIONS

MDM2 rs2279744 is associated with HCC susceptibility in Asians, and the dominant and codominant models are likely the most appropriate models to estimate HCC risk.

Mutations in apoptotic genes and micronucleus occurrence in vinyl chloride-exposed workers in China

BACKGROUND

Vinyl chloride is an occupational carcinogen which caused micronuclei in human directly. It has recently been demonstrated that micronuclei formation could generate a spectrum of genomic rearrangements and play a key role in the early tumorigenesis process. We aimed to investigate the association between polymorphisms in the apoptosis process related genes and micronuclei rate in vinyl chloride-exposed workers in China.

MATERIALS AND METHODS

Cytokinesis block micronucleus test was performed on 342 vinyl chloride-exposed workers and 107 nonexposed workers to determine chromosomal damage. The polymerase chain reaction and restriction fragment length polymorphism technique were used to detect nine Single Nucleotide Polymorphisms in the apoptosis process related genes.

RESULTS

There was a highly significant dose-response relationship between vinyl chloride exposure and chromosomal damage. Individuals carrying the variant heterozygote MDM2 -309T > G (rs2279744) and variant homozygote BCL2 -938C > A (rs2279115) were at higher risk for chromosomal damage compared with their wild-type genotype, respectively. Although individuals possessing the variant genotype of BAX -248G > A (rs4645878) had decreased risk compared with the corresponding wild type, this did not reach statistical significant.

CONCLUSION

Genetic polymorphisms in genes related to apoptosis process may have an impact on chromosomal damage induced by vinyl chloride. Environ. Mol. Mutagen. 58:39-45, 2017. © 2016 Wiley Periodicals, Inc.

Influence of MDM2 polymorphisms on squamous cell carcinoma susceptibility: a meta-analysis

PURPOSE

Controversial associations between single-nucleotide polymorphisms (rs2279744, rs937283, rs3730485) of the MDM2 gene and the etiology of squamous cell carcinomas (SCCs) have been reported. This merits further comprehensive assessment.

MATERIALS AND METHODS

We systematically reviewed the available data and conducted an updated meta-analysis to evaluate the genetic effect of MDM2 polymorphisms in SCC susceptibility, using Stata/SE 12.0 software.

RESULTS

After screening, 7,987 SCC cases and 12,954 controls from 26 eligible case-control studies were enrolled. Overall, compared with the control group, a significantly increased SCC risk was observed for the MDM2 rs2279744 polymorphism in the Asian population (test of association: odds ratio [OR] 1.12, P=0.027 for G vs T; OR 1.26, P=0.016 for GG vs TT; OR 1.25, P<0.001 for GG vs TT + TG; and OR 1.08, P=0.023 for carrier G vs T). In subgroup analysis by SCC type, a similarly increased esophageal SCC risk was detected (OR 1.19, P<0.001 for G vs T; OR 1.46, P<0.001 for GG vs TT; and OR 1.48, P=0.005 for GG vs TT + TG). Furthermore, MDM2-TP53 double mutation was statistically associated with increased SCC susceptibility overall (OR 1.52, P=0.001), especially in the Asian population (OR 1.49, P=0.022). However, no significant difference between the control and case groups was obtained for MDM2 rs937283 or rs3730485 under any genetic model (all P>0.05).

CONCLUSION

Our results highlight a positive association between the GG genotype of MDM2 rs2279744 polymorphism and an increased risk of esophageal SCC in the Asian population, which needs to be clarified by more large-scale studies.

Single-nucleotide polymorphism (c.309T>G) in the MDM2 gene and lung cancer risk

Murine double minute 2 (MDM2) is a negative regulator of p53. A single-nucleotide polymorphism (SNP) (rs2279744: c.309T>G) in the promoter region of the MDM2 gene has been shown to result in higher levels of MDM2 RNA and protein. Regarding the contribution of c.309T>G in the MDM2 gene to the lung cancer risk, previous studies are conflicting. In order to evaluate the association between c.309T>G and the lung cancer risk, a case-control study was performed. The MDM2 genotypes were determined in 762 lung cancer patients and in 700 cancer-free control subjects using the Smart Amplification Process. Statistical adjustment was performed for gender, age and pack-years of smoking. The distributions of c.309T>G (T/T, T/G, G/G) were 20.1, 49.7, 30.2% in the case group and 21.7, 47.9, 30.4% in the healthy-control group. There were no overall associations between the MDM2 genotypes and the risk of lung cancer [T/G genotype: Adjusted odds ratio (AOR), 1.30; 95% confidence interval (CI), 0.88-1.93; and G/G genotype: AOR, 1.18; 95% CI, 0.78-1.80]. The subgroup analysis of gender, histology, smoking status and epidermal growth factor receptor mutation status also indicated that there was no association with lung cancer. Additionally, the genotypes did not have an effect on the age at the time of diagnosis of lung cancer (P=0.25). In conclusion, the G allele frequency in the lung cancer cases was 0.551, which was similar to other studies. The results of the present study suggest that the c.309T>G is not significantly associated with lung cancer.

Rapid detection of SNP (c.309T>G) in the MDM2 gene by the Duplex SmartAmp method

Background

Genetic polymorphisms in the human MDM2 gene are suggested to be a tumor susceptibility marker and a prognostic factor for cancer. It has been reported that a single nucleotide polymorphism (SNP) c.309T>G in the MDM2 gene attenuates the tumor suppressor activity of p53 and accelerates tumor formation in humans.

Methodology

In this study, to detect the SNP c.309T>G in the MDM2 gene, we have developed a new SNP detection method, named “Duplex SmartAmp,” which enabled us to simultaneously detect both 309T and 309G alleles in one tube. To develop this new method, we introduced new primers i.e., nBP and oBPs, as well as two different fluorescent dyes that separately detect those genetic polymorphisms.

Results and Conclusions

By the Duplex SmartAmp method, the genetic polymorphisms of the MDM2 gene were detected directly from a small amount of genomic DNA or blood samples. We used 96 genomic DNA and 24 blood samples to validate the Duplex SmartAmp by comparison with results of the conventional PCR-RFLP method; consequently, the Duplex SmartAmp results agreed totally with those of the PCR-RFLP method. Thus, the new SNP detection method is considered useful for detecting the SNP c.309T>G in the MDM2 gene so as to judge cancer susceptibility against some cellular stress in the clinical setting, and also to handle a large number of samples and enable rapid clinical diagnosis.

MDM2 SNP285 does not antagonize the effect of SNP309 in lung cancer

Conflicting reports exist regarding the contribution of SNP309 in MDM2 to cancer risk. Recently, SNP285 was shown to act as an antagonist to SNP309 by overriding the effect of SNP309 on SP1-mediated transcription. Moreover, SNP285 modified the relationship between SNP309 and risk of breast, ovarian and endometrial cancer. We assessed whether SNP285 confounded the effect of SNP309 in lung cancer in a cohort of 720 controls and 556 cases. Our cohort included both Caucasians and African Americans. Neither SNP309 nor SNP285 was associated with lung cancer risk or survival. In addition, removal of individuals who carried the variant C allele of SNP285 did not modify the association between SNP309 with either lung cancer risk or survival. Although an effect of SNP285 has been demonstrated in breast, ovarian and endometrial cancer, our findings do not support a role for this SNP in lung cancer and raise the possibility that the effect of SNP285 is restricted to cancers in women.

MDM2 SNP309 polymorphism is associated with lung cancer risk in women: A meta-analysis using METAGEN

Lung cancer is the most common diagnosed malignancy and the leading cause of cancer-related mortality worldwide. Murine double minute 2 (MDM2) SNP309 polymorphisms have been reported to influence the risk of lung cancer. However, the published studies together with four subsequent meta-analyses have yielded contradictory results. To examine this inconsistency, we conducted a meta-analysis of 6,696 lung cancer cases and 7,972 controls from eight published case-control studies using METAGEN. Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated with STATA software and used to assess the strength of the association. In the overall analysis, a significant association between MDM2 SNP309 polymorphism and lung cancer risk was observed (OR, 1.143; 95% CI, 1.047-1.247). Moreover, stratified by ethnicity, a significant association was found in Asians (OR, 1.260; 95% CI, 1.111-1.429), but not in Europeans. Subgroup analysis of gender, histology and smoking status suggested that the MDM2 SNP309 genotype was associated with increased lung cancer risk in women (OR, 1.282; 95% CI, 1.062-1.548) and never smokers (OR, 1.328; 95% CI, 1.119-1.575). No statistically significant association was observed in males and ever smoking population, and no association was found in subgroup analysis based on histology. In conclusion, the association between MDM2 SNP309 and lung cancer was statistically significant, particularly in Asians, women and never smoking population.

Association of MDM2 SNP309 variation with lung cancer risk: evidence from 7196 cases and 8456 controls

Background

Evidence suggests that MDM2 T309G polymorphism may be a risk factor for several cancers. Increasing investigations have been conducted on the association of MDM2 T309G polymorphisms with lung cancer risk and have yielded conflicting results. Previous meta-analyses on this issue have reported inconclusive data. The aim of the present study was to derive a more precise estimation of the relationship.

Methods and Findings

Updated meta-analyses examining the association between MDM2 T309G polymorphism and lung cancer risk were performed. Separate analyses on ethnicity, smoking status, histological types and gender as well as source of controls were also implemented. Eligible studies were identified for the period up to Feb 2012. Lastly, ten publications including eleven case-control studies were selected for analysis. The overall data failed to indicate a significant association between MDM2 T309G polymorphism and lung cancer risk (GG vs TT OR = 1.14; 95%CI = 0.95−1.37; dominant model: OR = 1.05; 95%CI = 0.92−1.19; recessive model: OR = 1.12; 95%CI = 0.99−1.27). In a subgroup analysis by smoking status, increased lung cancer risk was shown among never-smokers (GG vs TT: OR = 1.76; 95%CI = 1.36−2.29; dominant model: OR = 1.48; 95%CI = 1.22−1.81; recessive model: OR = 1.37; 95%CI = 1.11−1.69). In subgroup analysis by gender, elevated risk was presented among women under a recessive model (OR = 1.29; 95%CI = 1.04−1.59). In the subgroup analysis by ethnicity, histological types and source of controls, no marked associations were observed.

Conclusions

Compared to the previous meta-analyses, the results of this study confirmed that MDM2 T309G polymorphism might be a risk factor for lung cancer among never-smokers. However, the data failed to suggest a marked association between the G allele of MDM2 T309G and lung cancer risk among Asians. More interestingly, subgroup analysis by gender indicated that homozygous GG alleles might raise lung cancer risk among females.

MDM2 SNP309 contributes to tumor susceptibility: a meta-analysis

The potentially functional polymorphism, SNP309, in the promoter region of MDM2 gene has been implicated in cancer risk, but individual published studies showed inconclusive results. To obtain a more precise estimate of the association between MDM2 SNP309 and risk of cancer, we performed a meta-analysis of 70 individual studies in 59 publications that included 26,160 cases with different types of tumors and 33,046 controls. Summary odds ratios (OR) and corresponding 95% confidence intervals (CIs) were estimated using fixed- and random-effects models when appropriate. Overall, the variant genotypes were associated with a significantly increased cancer risk for all cancer types in different genetic models (GG vs. TT: OR, 1.123; 95% CI, 1.056-1.193; GG/GT vs. TT: OR, 1.028; 95% CI, 1.006-1.050). In the stratified analyses, the increased risk remained for the studies of most types of cancers, Asian populations, and hospital- /population-based studies in different genetic models, whereas significantly decreased risk was found in prostate cancer (GG vs. TT: OR, 0.606; 95% CI, 0.407-0.903; GG/GT vs. TT: OR, 0.748; 95% CI, 0.579-0.968). In conclusion, the data of meta-analysis suggests that MDM2 SNP309 is a potential biomarker for cancer risk.

Polymorphisms in promoter sequences of MDM2, p53, and p16 genes in normal Japanese individuals

Research has been conducted to identify sequence polymorphisms of gene promoter regions in patients and control subjects, including normal individuals, and to determine the influence of these polymorphisms on transcriptional regulation in cells that express wild-type or mutant p53. In this study we isolated genomic DNA from whole blood of healthy Japanese individuals and sequenced the promoter regions of the MDM2, p53, and p16(INK4a) genes. We identified polymorphisms comprising 3 nucleotide substitutions at exon 1 and intron 1 regions of the MDM2 gene and 1 nucleotide insertion at a poly(C) nucleotide position in the p53 gene. The Japanese individuals also exhibited p16(INK4a) polymorphisms at several positions, including position -191. Reporter gene analysis by using luciferase revealed that the polymorphisms of MDM2, p53, and p16(INK4a) differentially altered luciferase activities in several cell lines, including the Colo320DM, U251, and T98G cell lines expressing mutant p53. Our results indicate that the promoter sequences of these genes differ among normal Japanese individuals and that polymorphisms can alter gene transcription activity.

MDM2 SNP309, gene-gene interaction, and tumor susceptibility: an updated meta-analysis

Background

The tumor suppressor gene p53 is involved in multiple cellular pathways including apoptosis, transcriptional control, and cell cycle regulation. In the last decade it has been demonstrated that the single nucleotide polymorphism (SNP) at codon 72 of the p53 gene is associated with the risk for development of various neoplasms. MDM2 SNP309 is a single nucleotide T to G polymorphism located in the MDM2 gene promoter. From the time that this well-characterized functional polymorphism was identified, a variety of case-control studies have been published that investigate the possible association between MDM2 SNP309 and cancer risk. However, the results of the published studies, as well as the subsequent meta-analyses, remain contradictory.

Methods

To investigate whether currently published epidemiological studies can clarify the potential interaction between MDM2 SNP309 and the functional genetic variant in p53 codon72 (Arg72Pro) and p53 mutation status, we performed a meta-analysis of the risk estimate on 27,813 cases with various tumor types and 30,295 controls.

Results

The data we reviewed indicated that variant homozygote 309GG and heterozygote 309TG were associated with a significant increased risk of all tumor types (homozygote comparison: odds ratio (OR) = 1.25, 95% confidence interval (CI) = 1.13-1.37; heterozygote comparison: OR = 1.10, 95% CI = 1.03-1.17). We also found that the combination of GG and Pro/Pro, TG and Pro/Pro, GG and Arg/Arg significantly increased the risk of cancer (OR = 3.38, 95% CI = 1.77-6.47; OR = 1.88, 95% CI = 1.26-2.81; OR = 1.96, 95% CI = 1.01-3.78, respectively). In a stratified analysis by tumor location, we also found a significant increased risk in brain, liver, stomach and uterus cancer (OR = 1.47, 95% CI = 1.06-2.03; OR = 2.24, 95%CI = 1.57-3.18; OR = 1.54, 95%CI = 1.04-2.29; OR = 1.34, 95%CI = 1.07-1.29, respectively). However, no association was seen between MDM2 SNP309 and tumor susceptibility in the stratified analysis by p53 mutation status (GG vs TT: OR = 1.17, 95% CI = 0.75-1.82 and TG vs TT: OR = 1.09, 95% CI = 0.89-1.34 for positive p53 mutation status; GG vs TT: OR = 0.95, 95% CI = 0.72-1.25 and TG vs TT: OR = 1.06, 95% CI = 0.85-1.30 for negative p53 mutation status).

Conclusions

The analyses indicate that MDM2 SNP309 serves as a tumor susceptibility marker, and that there is an association between MDM2 SNP309 and p53 Arg72Pro regarding tumor susceptibility. Further studies that take into consideration environmental stresses and functional genetic variants in the p53-MDM2-related genes are warranted.

Human papillomavirus seropositivity synergizes with MDM2 variants to increase the risk of oral squamous cell carcinoma

The increasing incidence of oral squamous cell carcinoma (OSCC) in young adults has been associated with sexually transmitted infections of human papillomavirus (HPV), particularly HPV16. Given the roles of p53 in tumor suppression and of HPV E6 and MDM2 oncoproteins in p53 degradation, we evaluated HPV16 L1 seropositivity and MDM2 promoter variants to examine their possible associations with OSCC risk in a case-control study of 325 patients and 335 cancer-free matched controls. Compared with individuals having MDM2-rs2279744 GT or GG genotypes and HPV16 L1 seronegativity, the TT genotype and HPV16 L1 seronegativity were found to be associated with an odds ratio (OR) of 1.25 [95% confidence interval (CI), 1.06-2.19] for OSCC risk, and GT/GG and HPV16 L1 seropositivity were associated with an OR of 2.81 (95% CI, 1.67-4.74). For those with both the TT genotype and HPV16 L1 seropositivity, the associated OR was 5.57 (95% CI, 2.93-10.6). Similar results were observed for the MDM2-rs937283 polymorphism. Moreover, there was a borderline significant or significant interaction between the individual or combined MDM2 genotypes of the two polymorphisms and HPV16 L1 seropositivity (P(int) = 0.060 for MDM2-rs2279744, P(int) = 0.009 for MDM2-rs937283, and P(int) = 0.005 for the combined MDM2 genotypes) on risk of OSCC. Notably, that effect modification was particularly pronounced in never smokers and never drinkers, and for oropharyngeal as opposed to oral cavity cancer. Taken together, our results indicate that the risk of OSCC associated with HPV16 L1 seropositivity is modified by MDM2 promoter polymorphisms.

MDM2 SNP309 and p53 Arg72Pro in cutaneous melanoma: association between SNP309 GG genotype and tumor Breslow thickness

A functional single nucleotide polymorphism (SNP) 309 T/G within mouse double minute 2 (MDM2) gene has been linked to onset and outcome of disease in tumors. Two published studies have shown discordant results regarding the effect of this SNP on age at diagnosis of cutaneous melanoma (CM) in Caucasian female populations. Here, we examined the age at diagnosis and clinical associations of CM with SNP309 and the related polymorphism, p53 Arg72Pro, in an Italian population (249 CM patients and 291 cancer-free controls) composed of women and men. MDM2 intronic region of 294 bp was directly sequenced, whereas Arg72Pro SNP was analyzed by polymerase chain reaction-restriction fragment length polymorphism. No associations were found among the SNP309, Arg72Pro, risk of CM, age at diagnosis and presence of metastasis in total subjects and when stratified according to the gender. The SNP309 was significantly associated with tumor Breslow thickness. The P-value in the minor allele recessive mode was 0.02, and the odds ratio (OR) adjusted for gender and age was 3.11 (95% confidential interval (CI)=1.21-8.00). The SNP309 is not associated with the risk and age of onset of CM, and the presence of metastasis in an Italian population but the SNP309 GG may be a risk genotype for increasing in tumor Breslow thickness.

Single-nucleotide polymorphisms in the p53 signaling pathway

The p53 tumor suppressor pathway is central both in reducing cancer frequency in vertebrates and in mediating the response of commonly used cancer therapies. This article aims to summarize and discuss a large body of evidence suggesting that the p53 pathway harbors functional inherited single-nucleotide polymorphisms (SNPs) that affect p53 signaling in cells, resulting in differences in cancer risk and clinical outcome in humans. The insights gained through these studies into how the functional p53 pathway SNPs could help in the tailoring of cancer therapies to the individual are discussed. Moreover, recent work is discussed that suggests that many more functional p53 pathway SNPs are yet to be fully characterized and that a thorough analysis of the functional human genetics of this important tumor suppressor pathway is required.

Effect of MDM2 SNP309 and p53 codon 72 polymorphisms on lung cancer risk and survival among non-smoking Chinese women in Singapore

Background

Single nucleotide polymorphism (SNP) 309 resulting in a T or G allele in the promoter of MDM2, the negative regulator of p53, has been suggested to affect cancer predisposition and age of onset, primarily in females. However, findings have been inconsistent in various cancers, and ethnicity appears to be a critical factor influencing the effects of the SNP on cancer risk. An increasing trend has been observed in the prevalence of lung cancers in non-smokers, especially females, though the underlying genetic basis is unclear.

Methods

We therefore examined the role of the SNPs in the p53 pathway (p53 codon 72 and MDM2 SNP309) on lung cancer risk and prognosis of a life-time non-smoking female Chinese population, in a hospital-based case-control study of 123 cases and 159 age-matched controls, by PCR analysis.

Results

Our findings reveal that the risk of lung cancer among individuals with the MDM2 SNP309 TT genotype was 2.1 (95% CI 1.01-4.36) relative to the GG genotype, contrary to initial expectations that the GG genotype with elevated MDM2 levels will increase cancer risk. Those who had this genotype in combination with the p53 Pro allele had a risk of 2.5 (95% CI 1.2-5.0). There was however no effect of either polymorphism on age at diagnosis of lung cancer or on overall survival.

Conclusions

The results thus demonstrate that the MDM2 SNP309 TT rather than the GG genotype is associated with increased risk of lung cancer in this population, suggesting that other mechanisms independent of increased MDM2 levels can influence cancer susceptibility.

MDM2 SNP309T>G polymorphism and risk of hepatocellular carcinoma: a case-control analysis in a Moroccan population

BACKGROUND

The Murine double minute 2 (MDM2) gene encodes a negative regulator of the p53 tumor suppressor protein. A single nucleotide polymorphism (SNP) in the MDM2 promoter (a T to G exchange at nucleotide 309) has been reported to produce accelerated tumor formation. The aim of this study was to investigate whether this functional SNP is associated with an enhanced risk of liver tumorigenesis in Moroccan patients.

METHODS

The study consisted in the comparison of 96 hepatocellular carcinomas (HCC) cases and 222 controls without HCC matched for age, gender and ethnicity. PCR-RFLP and sequencing methods were used to determine the genotype at the MDM2 SNP309T>G locus.

RESULTS

Overall, our results indicate that the GG genotype of SNP309 is significantly associated with an increased risk of HCC (odds ratio, OR=2.60, 95% CI, 1.08-6.28). Interestingly, despite a wide range of confidence interval, there is a trend associating the GG genotype with a high risk of HCC in males (OR=3.31; 95% CI, 0.93-11.82) and in HCV-infected patients (OR=3.7; 95% CI, 0.82-16.45). By contrast, no association between age at diagnosis and MDM2 SNP309 genotypes was observed in HCC patients (P=0.610).

CONCLUSION

Our findings suggest that the MDM2 309T>G polymorphism is an important modulator of hepatocellular carcinoma development in Moroccan patients.

Cigarette smoking, MDM2 SNP309, gene-environment interactions, and lung cancer risk: a meta-analysis

MDM2 SNP309 polymorphism was found to contribute to genetic susceptibility to lung cancer in humans. However, association studies on these polymorphisms in lung cancer cases have shown conflicting results. In order to derive a more precise estimation of the relationship, a meta-analysis was performed. Odds ratio (OR) with 95% confidence interval (CI) was applied to assess the strength of association between MDM2 SNP309 polymorphism and risk of lung cancer development. The logistic regression indicated that the genetic model was most likely to be recessive. Using a recessive model, the pooled OR estimating the genotype GG against the T-allele carriers (GT + TT) were calculated. Eight studies, including 6063 cases and 6678 controls, were involved in this meta-analysis. Overall meta-analysis indicated that MDM2 SNP309 GG genotypes have an approximate 16% increased risk for lung cancer development with a statistical significance (OR = 1.16; 95% CI: 1.01-1.34). In the subgroup analyses based on ethnicities, no significant elevated risk was associated with MDM2 SNP309 genotypes found in Asian and Europeans. No significant increased risk was associated with MDM2 SNP309 genotypes found in ever smokers. MDM2 SNP309 GG genotype had an approximate 36% enhanced risk of lung cancer development with statistical significance in never smokers (OR = 1.36; 95% CI: 1.10-1.68). Although some bias cannot be excluded, this meta-analysis supports the view that MDM2 SNP309 gene is a low-penetrance susceptible gene in the development of lung cancer, and the relationship of MDM2 SNP309 and lung cancer is stronger for never smokers.

Genotyping of single nucleotide polymorphism in MDM2 genes by universal fluorescence primer PCR and capillary electrophoresis

Single nucleotide polymorphism (SNP) 309 in the promoter region of the murine double minute 2 (MDM2) gene plays an important role in human tumorigenesis. We established a simple and effective CE method for SNP detection in the MDM2 gene. We designed one universal fluorescence-based nonhuman-sequence primer and one fragment-oriented primer, which were combined in one tube, and proceeded with the polymerase chain reaction (PCR). The amplicons were analyzed by capillary electrophoresis using single-strand conformation polymorphism method. PCR fragments generated from this two-in-one PCR displayed either T/T or G/G homozygosity or T/G heterozygosity. A total of 304 samples were blindly genotyped using this developed method, which included the DNA from 138 healthy volunteers, 43 chronic myeloid leukemia (CML) patients, and 123 colorectal cancer (CRC) patients. The results were confirmed by DNA sequencing and showed good agreement. The SSCP-CE method was feasible for SNP screening of MDM2 in large populations.

MDM2 SNP309 is associated with high grade node positive breast tumours and is in linkage disequilibrium with a novel MDM2 intron 1 polymorphism

INTRODUCTION

A functional polymorphism within MDM2, SNP309 T>G, has been linked to early onset cancer. This study examined clinical associations of breast cancer with SNP309 in a Scottish Caucasian population and investigated additional MDM2 intron 1 polymorphisms.

METHODS

Intron 1 of MDM2 was PCR amplified and directly sequenced from 299 breast cancer patients and 275 cancer free controls and compared with clinical and pathological parameters.

RESULTS

SNP309 was observed, for the control and breast cancer cohorts respectively, at frequencies of: T/T = 44.7% and 39.5%; G/T = 42.2% and 47.2%; G/G = 13.1% and 13.4%, indicating that SNP309 is not a predisposing factor for breast cancer. The 309G/G genotype was associated with high grade tumours (OR = 1.64, 95%CI = 1.06-2.53, p = 0.025) and greater nodal involvement (OR = 2.51, 95%CI = 1.26-4.98, p = 0.009). SNP309 was not associated with an earlier age of cancer diagnosis. No association was observed between genotype and age of breast cancer diagnosis when patients were stratified by menopausal status and estrogen receptor status. Three additional low frequency SNPs were identified: 344T>A, 285G>C and 443G>T, the latter two novel. SNP285 was in complete linkage disequilibrium with SNP309 (D' = 1.0) with the minor alleles being in phase with each other. Moreover, the 285C/C, 309G/G double homozygous genotype was only observed in the breast cancer cohort.

CONCLUSION

SNP309G/G is associated with poor prognostic breast cancer features in the Scottish population. Additionally, a novel SNP, SNP285, that is in linkage disequilibrium with SNP309, may also have a role in breast tumorigenesis.

MDM2 SNP309 does not confer an increased risk to oral squamous cell carcinoma but may modulate the age of disease onset

The MDM2 SNP309 has been associated with increased expression of the protein which could suppress p53 function, and has been shown to modulate risk to cancer. We have previously shown that overexpression of MDM2 is a common event in oral cancers. In the present study, we determined the association between the MDM2 SNP309 polymorphism and oral cancer in 207 oral cancer patients and 116 normal subjects. We genotyped the MDM2 SNP309 by PCR-RFLP. Logistic regression was adapted to calculate odds ratios for MDM2 SNP309 polymorphism from univariate and multivariable adjusted models. Our results suggest that MDM2 SNP309 does not confer increased risk to oral cancer (OR=1.55, 95% CI=0.77-3.11). However, the GG/TG genotype was associated with later disease onset in women above 55 years of age. Collectively, our data suggests that MDM2 SNP309 may modulate the risk to oral cancer and is a modifier of the age at oral cancer onset in women above the age of 55 years.

Impact of MDM2 single nucleotide polymorphism on tumor onset in head and neck squamous cell carcinoma

CONCLUSIONS

The GG genotype of MDM2 SNP309 is associated with an earlier onset of head and neck squamous cell carcinoma (HNSCC) in the Japanese population. SNP309 may be a key factor in the tumorigenesis of HNSCC as well as other hereditary or sporadic tumors.

OBJECTIVE

This study was designed to evaluate the association between the single nucleotide polymorphism (SNP) 309 in the MDM2 gene with HNSCC. An MDM2 protein down-regulates the p53 pathway. Recently, an important SNP was discovered in the MDM2 promoter region, which could affect the tumorigenesis of HNSCC by attenuation of the p53 pathway.

PATIENTS AND METHODS

Patients with 103 HNSCCs were genotyped using direct sequencing and real-time PCR. The relationship between the SNP309 genotypes and the clinicopathological features was statistically analyzed.

RESULTS

The number of patients genotyped to TT, TG, and GG was 29 (28%), 46 (44.7%), and 28 (27.2%), respectively. The average age at tumor onset was 65.6 years for TT, 62.9 years for TG, and 56.7 years for GG. The patients with the GG genotype had a significantly earlier tumor onset in comparison to those with the TT genotype (p=0.032).

Early onset lung cancer, cigarette smoking and the SNP309 of the murine double minute-2 (MDM2) gene

The polymorphism SNP309 (rs2279744) in the promoter region of the MDM2 gene has been shown to alter protein expression and may play a role in the susceptibility to lung cancer. The MDM2 protein is a key inhibitor of p53 and several mechanisms of MDM2/p53 interactions are presently known: modulating DNA-repair, cell-cycle control, cell growth and apoptosis.

We used 635 Caucasian patients diagnosed with lung cancer before 51 years of age and 1300 healthy gender and age frequency matched population Caucasian controls to investigate the association between the MDM2 SNP309 and the risk of developing early onset lung cancer. Conditional logistic models were applied to assess the genotype-phenotype association, adjusted for smoking.

Compared to the GG genotype, the adjusted ORs for the TG and TT genotype were 0.9 (95% CI: 0.7–1.5) and 1.0 (95% CI: 0.7–1.5), respectively. Also no association was found for histological subtypes of lung cancer. The strength of this study is that within young cases the genetic component to develop lung cancer may be greater. Our results indicate that the MDM2 SNP309 is not significantly associated with lung carcinogenesis but point towards gender-specific differences.

MDM2 promoter polymorphism SNP309 contributes to tumor susceptibility: evidence from 21 case-control studies

Since the identification of a well-characterized functional polymorphism named SNP309 in MDM2, abundant studies were published in the last 2 years to evaluate the association between SNP309 and tumor risk in diverse populations. However, the results remain conflicting rather than conclusive. Because a single study may have been underpowered to detect the effect of low-penetrance genes, a quantitative synthesis to accumulate data from different studies may provide better evidence on the association of genetic variant with tumor susceptibility. We conducted a meta-analysis on 14,770 cases with different tumor types and 14,524 controls from 25 published case-control studies to estimate the effect of SNP309 on tumor risk, as well as to quantify the potential between-study heterogeneity. We found that variant homozygote 309GG was associated with a significantly increased risk of all types of tumors [homozygote comparison: odds ratio (OR), 1.17, 95% confidential interval (95% CI), 1.04-1.33, P = 0.0002 for heterogeneity test; recessive model comparison: OR, 1.15, 95% CI, 1.03-1.28, P = 0.0005 for heterogeneity test]. Tumor type and ethnicity contributed to the substantial heterogeneity (69.5% for homozygote comparison and 77.2% for recessive model comparison). The analyses suggest that MDM2 SNP309 serves as a low-penetrance susceptibility tumor marker. Further large studies incorporate quantitative detection of different p53-responsible environmental stresses, p53 mutation status, and also functional genetic variants in p53-MDM2-related genes are warranted.

Genetic polymorphisms of MDM2, cumulative cigarette smoking and nonsmall cell lung cancer risk

Abnormalities of the tumor suppressor TP53 pathway are critical in the development of many cancers since it regulates cell cycle components and apoptosis. Murine double minute-2 (MDM2) protein is a central node in the p53 pathway and a direct negative regulator of p53. The MDM2 SNP309 (rs2279744) polymorphism increases MDM2 RNA and protein levels, attenuating the p53 pathway. The MDM2 SNP309 polymorphism was investigated in 1,787 Caucasian nonsmall cell lung cancer (NSCLC) patients and 1,360 healthy controls. Cases and controls were analyzed for associations with genotype and adjusted for age, gender, histology and smoking history. There were no overall associations between the MDM2 genotypes and risk of lung cancer (adjusted odds ratios [AORs] = 0.82 [95% confidence interval [CI] = 0.6-1.1] for the T/G genotype and AOR = 1.32 [95% CI = 0.9-2.0] for the G/G genotype). A statistically significant interaction (p = 0.01) was found between smoking and MDM2 genotypes. Consistent with this interaction, stratified analysis by pack-years of smoking demonstrated that the AORs of G/G vs. T/T were 1.56 (1.0-2.7), 1.46 (1.0-2.2), 0.80 (0.5-1.3) and 0.63 (0.4-1.1), respectively, for never, mild (<30 pack-years), moderate (30-57 pack-years) and heavy smokers (>or=58 pack-years). In conclusion, a strong gene-smoking interaction was observed between the MDM2 SNP309 and NSCLC risk.

Polymorphisms in apoptosis and cell cycle control genes and risk of brain tumors in adults

Despite the potential importance of the cell cycle and apoptosis pathways in brain tumor etiology, little has been published regarding brain tumor risk associated with common gene variants in these pathways. Using data from a hospital-based case-control study conducted by the National Cancer Institute between 1994 and 1998, we evaluated risk of glioma (n = 388), meningioma (n = 162), and acoustic neuroma (n = 73) with respect to 12 single nucleotide polymorphisms from 10 genes involved in apoptosis and cell cycle control: CASP8, CCND1, CCNH, CDKN1A, CDKN2A, CHEK1, CHEK2, MDM2, PTEN, and TP53. We observed significantly decreased risk of meningioma with the CASP8 Ex14-271A>T variant [odds ratio (OR)(AT), 0.8; 95% confidence interval (95% CI), 0.5-1.2; OR(AA), 0.5; 95% CI, 0.3-0.9; P(trend) = 0.03] and increased risk of meningioma with the CASP8 Ex13+51G>C variant (OR(GC), 1.4; 95% CI, 0.9-2.1; OR(CC), 3.6; 95% CI, 1.0-13.1; P(trend) = 0.04). The CT haplotype of the two CASP8 polymorphisms was associated with significantly increased risk of meningioma (OR, 1.7; 95% CI, 1.1-2.6), but was not associated with risk of glioma or acoustic neuroma. The CCND1 Ex4-1G>A variant was associated with increased risk for glioma, and the Ex8+49T>C variant of CCNH was associated with increased risk of glioma and acoustic neuroma. The MDM2 Ex12+162A>G variant was associated with significantly reduced risk of glioma. Our results suggest that common variants in the CASP8, CCND1, CCNH, and MDM2 genes may influence brain tumor risk. Future research in this area should include more detailed coverage of genes in the apoptosis/cell cycle control pathways.

MDM2 SNP309 and cancer risk: a combined analysis

A paper by Bond et al. reported that a single-nucleotide polymorphism (SNP) in the intronic promoter region of the mouse double minute 2 (MDM2) gene (called SNP309) can significantly change the expression of MDM2 and thereby suppress the p53 pathway. Furthermore, it was shown that SNP309 accelerates tumor formation in Li-Fraumeni patients. This initial report aroused the attention of many researchers, which investigated the role of SNP309 for the risk and the onset of cancer in different tissues. To provide a more robust estimate of the effect of this polymorphism on cancer risk, we combined the available genotype data for breast, colorectal and lung cancers. For breast cancer, we combined the data from 11 studies including 5737 cases and 6703 controls. For colorectal cancer, we combined the data from five studies with 1620 cases and 886 controls. For lung cancer, we performed a fixed-effect meta-analysis from seven studies including 4276 cases and 5318 controls. Our results suggest that the SNP309 variant does not have an impact on the risk of breast [odds ratio (OR) = 0.97, 95% confidence interval (CI) = 0.87-1.08] or colorectal cancers (OR = 0.97, 95% CI = 0.76-1.25). However, the combined estimate of the ORs for lung cancer revealed an increased risk for GG versus TT (OR = 1.27, 95% CI = 1.12-1.44). The data show that SNP309 alone has little or no effect on the risk of common cancers, but it might modify the time of tumor onset and prognosis.

A single nucleotide polymorphism in the p53 pathway interacts with gender, environmental stresses and tumor genetics to influence cancer in humans

Cancer biology finds itself in a post-genomic era and the hopes of using inherited genetic variants to improve prevention and treatment strategies are widespread. One of the largest types of inherited genetic variation is the single nucleotide polymorphism (SNP), of which there are at least 4.5 million. The challenge now becomes how to discover which polymorphisms alter cancer in humans and how to begin to understand their mechanism of action. In this report, a series of recent publications will be reviewed that have studied a polymorphism in the p53 tumor suppressor pathway, MDM2 SNP309. These reports have lent insights into how germline genetic variants of the p53 pathway could interact with gender, environmental stresses and tumor genetics to affect cancer in humans. Importantly, these observations have also exposed potential nodes of intervention, which could prove valuable in both the prevention and treatment of this disease in humans.

Haplotype structure and selection of the MDM2 oncogene in humans

The MDM2 protein is an ubiquitin ligase that plays a critical role in regulating the levels and activity of the p53 protein, which is a central tumor suppressor. A SNP in the human MDM2 gene (SNP309 T/G) occurs at frequencies dependent on demographic history and has been shown to have important differential effects on the activity of the MDM2 and p53 proteins and to associate with altered risk for the development of several cancers. In this report, the haplotype structure of the MDM2 gene is determined by using 14 different SNPs across the gene from three different population samples: Caucasians, African Americans, and the Ashkenazi Jewish ethnic group. The results presented in this report indicate that there is a substantially reduced variability of the deleterious SNP309 G allele haplotype in all three populations studied, whereas multiple common T allele haplotypes were found in all three populations. This observation, coupled with the relatively high frequency of the G allele haplotype in both and Caucasian and Ashkenazi Jewish population data sets, suggests that this haplotype could have undergone a recent positive selection sweep. An entropy-based selection test is presented that explicitly takes into account the correlations between different SNPs, and the analysis of MDM2 reveals a significant departure from the standard assumptions of selective neutrality.

Polymorphisms in the FAS and FASL genes and risk of lung cancer in a Korean population

BACKGROUND

The FAS and FASL system play an important role in regulating extrinsic apoptotic pathway and inappropriate regulation of this signaling pathway contributes to lung tumorigenesis. Polymorphisms in the promoter region of the FAS (-1377G>A and -670A>G) and FASL (-844C>T) have been shown to alter the transcriptional activities of these genes. In order to evaluate the contribution of these polymorphisms to the risk of lung cancer, we carried out a case-control study in a Korean population.

METHODS

The FAS and FASL genotypes were determined in 582 lung cancer patients and 582 healthy control subjects who were frequency-matched for age and gender.

RESULTS

The FAS and FASL genotypes and the FAS haplotypes exhibited no apparent relationship with the risk of lung cancer. In addition, there was no significant interaction between the FAS and FASL polymorphisms in the development of lung cancer.

CONCLUSION

These results suggest that the FAS-1377G>A and -670A>G and FASL-844C>T polymorphisms do not significantly affect the susceptibility to lung cancer in Koreans.