The MDM2 promoter SNP285C/309G haplotype diminishes Sp1 transcription factor binding and reduces risk for breast and ovarian cancer in Caucasians

MDM2 plays a key role in modulating p53 function. The MDM2 SNP309T > G promoter polymorphism enhances Sp1 binding and has been linked to cancer risk and young age at diagnosis although with conflicting evidence. We report a second MDM2 promoter polymorphism, SNP285G > C, residing on the SNP309G allele. SNP285C occurs in Caucasians only, where 7.7% (95% CI 7.6%-7.8%) of healthy individuals carry the SNP285C/309G haplotype. In?vitro analyses reveals that SNP309G enhances but SNP285C strongly reduces Sp1 promoter binding. Comparing MDM2 promoter status among different cohorts of ovarian (n?= 1993) and breast (n?= 1973) cancer patients versus healthy controls (n?= 3646), SNP285C reduced the risk of both ovarian (OR 0.74; CI 0.58-0.94) and breast cancer (OR 0.79; CI 0.62-1.00) among SNP309G carriers.     

The MDM2 SNP309T>G Polymorphism Increases Bladder Cancer Risk among Caucasians: a Meta-analysis

Published studies have evaluated associations between the MDM2 SNP309T>G polymorphism and bladder cancer susceptibility. However, these generated inconsistent results. The aim of the present investigation was to quantify the strength of association between MDM2 SNP309T>G polymorphism and bladder cancer risk by conducting a meta-analysis. We searched PubMed and Embase for related studies that had been published in English before April 1, 2014 and associations were assessed by summarizing the odds ratios (ORs) with thecorresponding 95% confidence intervals (CIs). Five case-control studies with a total of 972 cases and 1,012 controls were finally identified to be eligible for the meta-analysis. Overall, the results indicated that there was no significant association between the MDM2 SNP309T>G polymorphism and bladder cancer risk (for the allele model G vs. T: OR=1.08, 95% CI 0.85-1.36, p=0.54; for the co-dominant model GG vs. TT: OR=1.20, 95% CI 0.74-1.93, p=0.46; for the dominant model GG+GT vs. TT: OR=0.98, 95% CI 0.80-1.20, p=0.83; for the recessive model GG vs. GT+TT: OR=1.20, 95% CI 0.83-1.74, p=0.33). However, on subgroup analysis by ethnicity, significant associations were found in Caucasians in three models (for the allele model G vs. T: OR=1.41, 95% CI 1.10-1.81, p=0.006; for the co-dominant model GG vs. TT: OR=2.16, 95% CI 1.28-3.63, p=0.004; for therecessive model GG vs. GT+TT: OR=2.06, 95% CI 1.31-3.22, p=0.002). In summary, the present meta-analysis provides evidence that the genotype for the MDM2 SNP309T>G polymorphism may be associated with genetic susceptibility to bladder cancer among Caucasians.     

Association between MDM2 promoter SNP309 T/G polymorphism and liver cancer risk - a meta-analysis

Background: Many studies have investigated the association between the MDM2 promoter SNP309 T/Gpolymorphism and liver cancer risk, but inconsistencies make drawwing definitive conclusions difficult. Methods:We therefore searched main databases for articles relating MDM2 SNP309 T/G polymorphism to risk of livercancer in humans and estimated summary odds ratio (OR) with 95% confidence intervals (95% CI) to assessthe possible association in a meta-analysis. Results: The main analysis revealed no significant heterogeneity, andthe pooled ORs of fixed-effects were all significant (for G versus T, OR = 1.59, 95% CI 1.42-1.78; for GG versusTT, OR = 2.45, 95% CI 1.93-3.12; for GT versus TT, OR = 1.70, 95% CI 1.38-2.09; for GG versus GT, OR =1.49, 95% CI 1.24-1.79; for GG and GT versus TT, OR = 1.95, 95% CI 1.61-2.38; for GG versus TT and GT,OR = 1.73, 95% CI 1.46-2.07). Subgroup analyses by ethnicity and sensitivity analyses both showed associationsto remain significant. Conclusion: The present meta-analysis of available data showed a significant associationbetween the MDM2 SNP309 T/G polymorphism and liver cancer risk, the MDM2 SNP309 G allele contributingto increased risk in both Asians and Caucasians in a graded, dose-dependent fashion.     

MDM2 启动子区309 位点基因多态性与乳腺癌风险的关系*

目的:采用病例- 对照研究检测MDM2 启动子区309 位点T>G 单核苷酸多态（SNP 309）在中国女性人群中的频率分布,分析其与中国女性乳腺癌发病风险的关系。方法:提取病例组698 例原发性乳腺癌患者及对照组525 例健康人的外周血单核细胞DNA,采用聚合酶链反应- 限制性片段长度多态性（PCR-RFLP ）分析法,检测MDM2 启动子区309 位点基因多态性,确定此位点三种基因型,即T/T、T/G、G/G 基因型。统计分析病例组和对照组人群MDM2 SNP 309 各基因型频率分布,及各基因型与乳腺癌发病风险的相关性。结果:在研究的病例组与对照组整体人群中,经年龄、月经状态、家族史及生育史等因素校正后,与MDM2 SNP 309 T/T基因型比较,T/G 型及G/G 型与乳腺癌的发病风险无显著相关性（T/G,adjusted OR= 1.2,95%CI:0.8～1.6,P=0.30;G/G,adjusted OR= 1.0,95%CI:0.7～1.5,P=0.88）。 进一步分层分析后显示:在绝经后人群中,与T/T基因型比较,T/G 基因型及G/G 基因型显著增加乳腺癌的发病风险（T/G,adjusted OR= 1.8,95%CI:1.2～3.0,P=0.011;G/G,adjusted OR= 1.9,95%CI:1.2～3.3,P=0.014）。 提示绝经后人群携带T/G 型、G/G 型者比携带T/T基因型者患乳腺癌的风险分别升高约1.8、1.9 倍。在绝经前人群中,各基因型与乳腺癌的发病风险无显著相关性（P>0.05）。 结论:MDM2 启动子309 位点突变型G 等位基因携带者显著增加绝经后女性乳腺癌的发病风险。      

Effect of a single nucleotide polymorphism in the murine double minute 2 promoter (SNP309) on the sensitivity to topoisomerase II-targeting drugs

A single nucleotide polymorphism (SNP) SNP309 (T-->G) in the murine double minute 2 (MDM2) promoter creates a high-affinity Sp1 binding site and increases the expression of MDM2 mRNA and protein. Approximately 40% of the populations harbor at least one variant allele and 12% to 17% are homozygous G/G at codon 309. This MDM2 SNP increases susceptibility to cancer and decreases the response of cancer cells to certain forms of treatment, such as radiation therapy and DNA-damaging drugs. Topoisomerase II (TopoII)-targeting agents are commonly used chemotherapeutic drugs with a broad spectrum of activity. However, resistance to TopoII poisons limits their effectiveness. We show that MDM2 SNP309 rendered a panel of cancer cell lines that are homozygous for SNP309 selectively resistant (approximately 10-fold) to certain TopoII-targeting chemotherapeutic drugs (etoposide, mitoxantrone, amsacrine, and ellipticine). The mechanism underlying this observation was Mdm2-mediated down-regulation of TopoII; on drug exposure, MDM2 bound to TopoII and resulted in decreased cellular enzyme content. Knockdown of MDM2 by RNA interference stabilized TopoIIalpha and decreased resistance to TopoII-targeting drugs. Thus, MDM2 SNP309 (T-->G) may represent a relatively common, previously unappreciated determinant of drug sensitivity. Given the frequency of SNP309 in the general population (40% in heterozygous T/G and 12% in homozygous G/G condition), our observation may have important implications for the individualization of cancer chemotherapy.     

Polymorphisms in the MDM2 promoter and risk of breast cancer: a case-control analysis in a Chinese population

MDM2 is a phosphoprotein that interacts with P53 and inhibits its activity. Recently, a T/G substitution (SNP309) in the promoter of MDM2 was identified and has been demonstrated to be associated with an increased MDM2 expression and a significantly earlier age of onset of several tumors, including breast cancer. To test the hypothesis that this functional variant in the MDM2 promoter is associated with risk of breast cancer, we conducted a molecular epidemiological study of 366 breast cancer cases (BC), 263 patients with benign breast diseases (BBD) and 605 cancer-free controls in China, in which we genotyped this T/G variant and another common insertion/deletion polymorphism (Del1518) in the MDM2 promoter and evaluated the associations between these two polymorphisms and breast cancer risk. We found that the variant allele frequencies of these two polymorphisms were not statistically different between the cases and controls (SNP309G: 0.500, 0.542, and 0.506 in BC, BBD, and controls, respectively, and Del1518−: 0.296, 0.308, and 0.297 in BC, BBD, and controls, respectively). Logistic regression analyses revealed that the variant genotypes of both MDM2 SNP309 and Del1518 polymorphisms were not significantly associated with risk of breast cancer (adjusted OR, 1.03; 95% CI, 0.74–1.42 for SNP309 TG and GG; and adjusted OR, 1.09; 95% CI, 0.83–1.43 for Del1518 +/− and −/−). These findings suggest that these two MDM2 promoter variants may not play a major role in the etiology of breast cancer.     

MDM2 SNP309 G allele increases risk but the T allele is associated with earlier onset age of sporadic breast cancers in the Chinese population

Sporadic breast cancer in women <40 years is uncommon inCaucasians, in contrast to a much earlier onset in Chinese Asians.However, the molecular determinants for this earlier onset areunclear. It has been reported that SNP309 in the promoter ofMDM2, the negative regulator of p53, affects the onset age ofcancers in females. Essentially, the G allele, rather than theT allele, has been suggested to accelerate the age of canceronset. Hence, we examined if MDM2 and p53 polymorphisms wouldbe determinants of the early onset phenomenon in Chinese women.Our results indicate that the MDM2 SNP309 G allele is more prevalentin the Chinese population compared with reported frequenciesin Caucasians, and increases breast cancer risk of both sporadiccases and those with family history. However, it was the T/Tgenotype that was associated with earlier onset age of sporadicbreast cancers in contrast to the G allele that was associatedwith the familial cases. Though p53 codon 72 single-nucleotidepolymorphism (SNP) did not affect general cancer risk or ageof onset, arginine homozygozity, in contrast to proline homozygozity,was found to decrease breast cancer risk in the later onsetsporadic cases. Both SNP309 and codon 72 polymorphisms did notaffect the stage of cancer. Together, the data suggest thatthough the MDM2 SNP309 G allele is a risk factor for breastcancer, it does not accelerate, but delays the onset of thesporadic disease in Chinese women, highlighting that differencesin ethnicity and family history may influence the role of MDM2SNP309 in cancer susceptibility. Abbreviations: Arg, arginine; ER, estrogen receptor; OR, odds ratio; PCR, polymerase chain reaction; Pro, proline; SNP, single-nucleotide polymorphism Received September 3, 2007; revised January 17, 2008; accepted January 18, 2008.     

MDM2 promoter SNP309 is associated with the risk of hepatocellular carcinoma in patients with chronic hepatitis C.

PURPOSE: A single nucleotide polymorphism (SNP) in the promoter region of MDM2 gene, SNP309, has recently been shown to be associated with accelerated tumor formation in both hereditary and sporadic cancers in humans. However, the association of SNP309 with hepatocellular carcinoma is unknown. We evaluated the association of SNP309 with the risk of hepatocellular carcinoma development among Japanese patients with chronic hepatitis C virus infection. EXPERIMENTAL DESIGN: We genotyped the SNP309 at the MDM2 promoter in 435 Japanese patients with chronic hepatitis C virus infection, including 187 patients with hepatocellular carcinoma and 48 healthy subjects, using a fluorogenic PCR. Presence of SNP was also confirmed by direct sequencing of the MDM2 promoter region. RESULTS: The proportion of G/G genotype of the SNP309 in patients with hepatocellular carcinoma (33%) was significantly higher than that in patients without hepatocellular carcinoma (23%), with an odds ratio (95% confidence interval) of 2.28 (1.30-3.98). A multivariate analysis revealed that MDM2 SNP309 (G/G versus T/T), age >60 years, male gender, presence of cirrhosis, serum alpha-fetoprotein >20 mug/L, and serum albumin <3.2 g/dL were independently associated with the hepatocellular carcinoma development at odds ratio of 2.27, 2.46, 3.08, 4.15, 4.87, and 6.33, respectively. CONCLUSIONS: The MDM2 promoter SNP309 is associated with the presence of hepatocellular carcinoma in Japanese patients with chronic hepatitis C.     

MDM2 promoter polymorphism and pancreatic cancer risk and prognosis.

PURPOSE: The mouse double minute 2 homologue (MDM2) -309T/G promoter polymorphism has been associated recently with the development and prognosis of a variety of tumors. The G allele is associated with increased affinity for Sp1 binding and higher MDM2 mRNA and protein levels, leading to diminished tumor suppressor activity of the p53 pathway. We hypothesized that the G allele is also associated with increased risk and worse outcome in pancreatic cancer. EXPERIMENTAL DESIGN: We evaluated the association between MDM2 309T/G and the risk of histologically confirmed pancreatic adenocarcinoma at Massachusetts General Hospital using unconditional logistic regression (123 cases and 372 controls). Complete overall survival and progression-free survival data were also available for 109 newly diagnosed patients. RESULTS: The adjusted odds ratios (95% confidence intervals) of pancreatic cancer associated with the MDM2 T/G and G/G genotypes compared with TT were 1.89 (1.20-2.99) and 2.07 (1.03-4.16), respectively (adjusting for age, gender, smoking status, and pack-years of smoking). In Cox proportional hazards model with the wild-type T/T genotype as the reference category and adjusting for stage, treatment, and performance status, both the heterozygous T/G and the homozygous G/G genotypes were associated with decreased progression-free survival [adjusted hazard ratio (95% confidence interval), 1.67 (0.98-2.84) for T/G and 2.28 (1.11-4.71) for G/G] and overall survival [2.64 (1.23-5.67) for T/G and 3.12 (1.22-7.91) for G/G]. CONCLUSIONS: The G allele of the MDM2 -309T/G polymorphism is associated with 2- to 3-fold increase risk and progression of pancreatic adenocarcinoma and a corresponding decrease in survival.     

MDM2 SNP309 accelerates breast and ovarian carcinogenesis in BRCA1 and BRCA2 carriers of Jewish–Ashkenazi descent

A functional single nucleotide polymorphism in the promoter of the MDM2 gene, SNP309 (T>G), was recently found to accelerate tumorigenesis in early onset cancer cases. The SNP309 G-allele, introduces an SP1 site in the MDM2 promoter, resulting in enhanced MDM2 expression and activity. Thus, the G-allele of MDM2 SNP309 may represent a cancer predisposing allele. In this report, we assessed the role of SNP309 as a modifier of mutant BRCA1/BRCA2 alleles in inherited breast and ovarian cancer cases among Ashkenazi–Jewish (AJ) women. We genotyped several subsets of AJ women: 138 healthy women, 140 affected BRCA1/2 mutation carriers, 120 asymptomatic BRCA1/2 mutation carriers and 187 sporadic breast cancer patients. The frequency of GG genotype of SNP309 was similar among the different groups. Interestingly, we found almost three times higher frequency of the GG genotype among BRCA1/2 carriers diagnosed with breast and/or ovarian cancer at or under the age of 51 years compared with carriers diagnosed with cancer above the age of 51 years (allele frequency, P = 0.019). The GG genotype was significantly associated with breast and ovarian cancer risk among BRCA1/2 carriers diagnosed before 51 years of age (OR, 3.93; 95% CI, 1.41–10.90, P = 0.009). No significant difference in frequency of the GG genotype was observed between early and late onset non-carrier cancer patients and no association with risk, OR, 1.30; 95% CI 0.69–2.47, P = 0.419). These data suggest that MDM2 SNP309 acts as a modifier of mutant BRCA1/2 mutant alleles in AJ and may accelerate breast and ovarian carcinogenesis in genetically predisposed individuals.     

No association between SNP309 promoter polymorphism in the MDM2 and cervical cancer in a study from northeastern Brazil

Background: A functional variant in the MDM2 promoter (a T/G substitution, SNP309) was found to be associated with increased expression of MDM2 gene products and at significantly earlier age onset of tumors in both hereditary Li-Fraumeni individuals and sporadic cancer patients. We tested the hypothesis that this functional variant was associated with either risk or early age diagnosis of cervical cancer in a Brazilian population. Methods: A primer-introduced restriction analysis PCR assay was used to genotype the MDM2 SNP309 of 72 cervical carcinoma patients and 100 healthy women. Results: No statistically significant association was observed between SNP309 and cervical cancer. We did not find allele or genotype frequency differences between the group of patients with cancer diagnosis at an early age (younger than 40 years old) and the group of older patients. Conclusions: Our findings suggest that SNP309 MDM2 may not be a risk factor for cervical cancer.