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 285G–309G haplotype is associated with an earlier age of tumour onset in patients with Li-Fraumeni syndrome

In the Li-Fraumeni syndrome (LFS) resulting from germline TP53 mutations, the MDM2 SNP309G allele has been shown to be associated with an earlier age of tumour onset, however the significance of this association is controversial. The 285C variation, also located in the MDM2 promoter, has been shown to reduce the strength of Sp1 binding to MDM2 promoter, antagonizing the effect of the 309G variation. In this study, we investigated the interaction of the MDM2 SNP285 and 309 in a large series of 195 LFS patients. Although we observed a lower mean age of tumour onset in patients with MDM2 SNP309 T/G or G/G genotype (23.1 years) than in patients with T/T genotype (27.3 years), the difference was not statistically significant. In contrast, patients with the 285–309 G–G haplotype develop tumours 5 years earlier than patients harbouring other haplotypes (p = 0.044). This result shows that the MDM2 285–309 G–G is a higher risk haplotype in patients with germline TP53 mutations. This study confirms that the MDM2 309G variation is deleterious when its effect is not neutralized by the 285C variation and illustrates the interfering effects of SNPs located within a gene acting as modifier factor in a Mendelian disease.     

MDM2 SNP309 polymorphism contributes to endometrial cancer susceptibility: evidence from a meta-analysis

Objective

The SNP309 polymorphism (T-G) in the promoter of MDM2 gene has been reported to be associated with enhanced MDM2 expression and tumor development. Studies investigating the association between MDM2 SNP309 polymorphism and endometrial cancer risk reported conflicting results. We performed a meta-analysis of all available studies to explore this association.

Methods

All studies published up to August 2013 on the association between MDM2 SNP309 polymorphism and endometrial cancer risk were identified by searching electronic databases PubMed, Web of Science, EMBASE, and Chinese Biomedical Literature database (CBM). The association between the MDM2 SNP309 polymorphism and endometrial cancer risk was assessed by odds ratios (ORs) together with their 95% confidence intervals (CIs).

Results

Eight case–control studies with 2069 endometrial cancer cases and 4546 controls were identified. Overall, significant increase of endometrial cancer risk was found when all studies were pooled in the meta-analysis (GG vs. TT: OR = 1.464, 95% CI 1.246–1.721, P < 0.001; GG vs. TG + TT: OR = 1.726, 95% CI 1.251–2.380, P = 0.001; GG + TG vs. TT: OR = 1.169, 95% CI 1.048–1.304, P = 0.005). In subgroup analysis by ethnicity and HWE in controls, significant increase of endometrial cancer risks were observed in Caucasians and studies consistent with HWE. In subgroup analysis according to study quality, significant associations were observed in both high quality studies and low quality studies.

Conclusions

This meta-analysis suggests that MDM2 SNP309 polymorphism contributes to endometrial cancer susceptibility, especially in Caucasian populations. Further large and well-designed studies are needed to confirm this association.     

MDM2 promoter SNP309 is associated with an increased susceptibility to chronic lymphocytic leukemia and correlates with MDM2 mRNA expression in Chinese patients with CLL

A single nucleotide polymorphism (SNP) at position 309 in the promoter region of MDM2 leading to increased expression of MDM2 and attenuated function of p53 has recently been suggested as an unfavorable prognostic marker in chronic lymphocytic leukemia (CLL) although this has been questioned. The MDM2 SNP309 genotypes in 173 CLL patients and 260 healthy controls were detected by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method, which was confirmed by direct DNA sequencing. Compared with the T/T genotype, the SNP309 G/G genotype instead of T/G heterozygote was associated with a significantly increased risk of CLL (OR = 2.84; 95% CI 1.61-5.03; p < 0.001). Age at onset of CLL was similar irrespective of MDM2 status. MDM2 mRNA expression within CLL of G/G genotype was significantly higher than that in T/G (p = 0.009) and T/T genotypes (p < 0.001). Excluding patients with p53 deletions or mutations enhanced the significance of the findings (G/G vs. T/T, p < 0.001; G/G vs. T/G p = 0.001), which prompted us to study the role of the polymorphism in p53 wild-type individuals. In the p53 wild-type groups, survival analysis showed that the patients with MDM2 SNP309 G/G and T/G genotypes both had significantly shorter treatment-free survival (TFS) than SNP309 T/T genotype. Notably, univariate and multivariate analyses showed that MDM2 SNP309 genotypes were associated with TFS. These data show that MDM2 309G polymorphisms contribute to the risk of developing CLL. The unfavorable MDM2 SNP309 G/G genotype was associated with an increase of MDM2 mRNA expression. MDM2 SNP309 was found to be associated with TFS in p53 wild-type Chinese CLL populations.     

Evaluation of TP53 Pro72Arg and MDM2 SNP285–SNP309 polymorphisms in an Italian cohort of LFS suggestive patients lacking identifiable TP53 germline mutations

Li-Fraumeni syndrome (LFS) is a rare genetic cancer predisposition disease, partly determined by the presence of a TP53 germline mutation; lacking thereof, in presence of a typical LFS phenotype, defines a wide group of ‘LFS Suggestive’ patients. Alternative LFS susceptibility genes have been investigated without promising results, thus suggesting other genetic determinants involvement in cancer predisposition. Hence, this study explores the single and combined effects of cancer risk, age of onset and cancer type of three single nucleotide polymorphisms (SNPs)—TP53 Pro72Arg, MDM2 SNP285 and SNP309—already described as modifiers on TP53 mutation carriers but not properly investigated in LFS Suggestive patients. This case–control study examines 34 Italian LFS Suggestive lacking of germline TP53 mutations and 95 tumour-free subjects. A significant prevalence of homozygous MDM2 SNP309 G in the LFS Suggestive group (p < 0.0005) confirms its contribute to cancer susceptibility, also highlighted in LFS TP53 positive families. Conversely its anticipating role on tumour onset has not been confirmed, as in our results it was associated with the SNP309 T allele. A strong combined outcome with a ‘dosage’ effect has also been reported for TP53 P72 and MDM2 SNP309 G allele on cancer susceptibility (p < 0.0005). Whereas the MDM2 SNP285 C allele neutralizing effect on MDM2 SNP309 G variant is not evident in our population. Although it needs further evaluations, obtained results strengthen the role of MDM2 SNP309 as a genetic factor in hereditary predisposition to cancer, so improving LFS Suggestive patients management.     

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.     

Risk of MDM2 SNP309 alone or in combination with the p53 codon 72 polymorphism in acute myeloid leukemia

A single nucleotide polymorphism (SNP) in the promoter of MDM2 gene, SNP309 T > G (a T–G exchange at nucleotide 309 in the first intron), can increase the expression level of MDM2, thereby causing an impairment of p53 tumor suppressor activity. A G–C exchange at p53 codon 72 polymorphism results in a substitution of proline (Pro) for arginine (Arg) in the transactivation domain, which was shown to alter the primary structure of the p53 protein. Both polymorphisms have been implicated in cancer. To investigate whether that MDM2 SNP309 and p53 codon 72 polymorphism should be at least partially responsible for genetic susceptibility to acute myeloid leukemia (AML), both polymorphisms were determined in a case–control study consisting of 231 AML patients and 128 normal individuals. The MDM2 SNP309G allele was associated with increased risk of AML. Furthermore, the p53 codon 72 and MDM2 SNP309 polymorphisms did not associate with age of onset and any other clinical parameters studied. When the p53 and MDM2 polymorphisms were combined, no multiplicative joint effect between the MDM2 GG and p53 Pro/Pro genotypes exists in the risk of developing AML. These results suggest that the MDM2 SNP309 homozygous GG genotype may be a genetic susceptibility factor in the pathogenesis of AML.     

Polymorphisms of p53 and MDM2 genes are associated with severe toxicities in patients with non-small cell lung cancer

Adverse events in platinum-based chemotherapy for patients with advanced non-small cell lung cancer (NSCLC) are major challenges. In this study, we investigated the role of the p53 and MDM2 genes in predicting adverse events in NSCLC patients treated with platinum-based chemotherapy. Specifically, we examined the p53 p. Pro72Arg (rs1042522), MDM2 c.14 + 309T>G (rs2279744) and MDM2 c.− 461C > G (rs937282) polymorphisms using PCR-based restriction fragment length polymorphism (RFLP) in 444 NSCLC patients. We determine that MDM2 c.14 + 309T > G was significantly associated with severe hematologic and overall toxicities for advanced NSCLC patients treated with platinum-based chemotherapy, especially for patients aged 57 and younger. This was also true for patients with adenocarcinoma. Second, we determine that severe gastrointestinal toxicities in patients with heterozygous MDM2 c.−461C > G were significantly higher than in patients with the G/G genotype. Third, patients with the MDM2 c.−461C > G − c.14 + 309T > G CT haplotype show much higher toxicities than those of CG haplotype. Moreover, patients carrying the MDM2 c.−461 > G –c.14 + 309T > G CG/CT diplotype exhibited higher toxicities than those carrying CG/CG. Fourth, we found that the p53 p. Pro72Arg polymorphism interacts with both age and genotype. In addition, no significant associations were observed between the 3 SNPs and the response to first-line platinum-based chemotherapy in advanced NSCLC patients. In summary, we found that the p53 p. Pro72Arg, MDM2 c.14 + 309T > G and MDM2 c.−461C > G polymorphisms are associated with toxicity risks following platinum-based chemotherapy treatment in advanced NSCLC patients. We suggest that MDM2 c.14 + 309T > G may be used as a candidate biomarker to predict adverse events in advanced NSCLC patients who had platinum-based chemotherapy treatment.     

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.     

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, p _het?=?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.     

<Emphasis Type="Italic">MDM2</Emphasis> SNP309 and <Emphasis Type="Italic">TP53</Emphasis> R72P associated with severe and febrile neutropenia in breast cancer patients treated with 5-FU/epirubicin/cyclophosphamide

The aim of this study was to investigate the association of two genetic polymorphisms, MDM2 SNP309 and TP53 R72P, with incidence of neutropenia in breast cancer patients treated with 5-FU/epirubicin/cyclophosphamide (FEC). Primary breast cancer patients (n = 216) treated with adjuvant FEC (60, 75 or 100 mg/m²) were included in this study. The association of genotypes of MDM2 SNP309 and TP53 R72P, determined by TaqMan SNP Genotyping Assays, with febrile neutropenia (FN) was investigated. In the patients treated with FEC100, G/G genotype for MDM2 SNP309 (G/G genotype ^MDM2 ) was significantly (P < 0.01) associated with a lower incidence (5.3 vs. 39.2%) of severe neutropenia (<100/mm³) than with T/T + T/G genotypes ^MDM2 , and C/C genotype for TP53 R72P (C/C genotype ^TP53 ) was significantly (P = 0.03) associated with a higher incidence (58.3 vs. 27.3%) of FN than with G/G + G/C genotypes ^TP53 . The combination of C/C genotype ^TP53 and T/T + T/G genotype ^MDM2 showed the highest risk for developing severe neutropenia (83.3%) and FN (62.5%) than any other combinations. In the patients treated with FEC60 or FEC75, there was no significant association of MDM2 SNP309 and TP53 R72P with severe neutropenia and FN. MDM2 SNP309 and TP53 R72P are significantly associated with severe neutropenia and FN, respectively, in breast cancer patients treated with FEC100, and especially their combination may be a useful predictor of severe neutropenia and FN.     

High-risk HPV infection after five years in a population-based cohort of Chilean women

Background

Single-nucleotide polymorphisms within TP53 gene (codon 72 exon 4, rs1042522, encoding either arginine or proline) and MDM2 promoter (SNP309; rs2279744), have been independently associated with increased risk of several cancer types. Few studies have analysed the role of these polymorphisms in the development of hepatocellular carcinoma.

Methods

Genotype distribution of TP53 codon 72 and MDM2 SNP309 in 61 viral hepatitis-related hepatocellular carcinoma cases and 122 blood samples (healthy controls) from Italian subjects were determined by PCR and restriction fragment length polymorphism (RFLP).

Results

Frequencies of TP53 codon 72 alleles were not significantly different between cases and controls. A significant increase of MDM2 SNP309 G/G and T/G genotypes were observed among hepatocellular carcinoma cases (Odds Ratio, OR = 3.56, 95% Confidence Limits, 95% CI = 1.3-9.7; and OR = 2.82, 95% CI = 1.3-6.4, respectively).

Conclusions

These results highlight a significant role of MDM2 SNP309 G allele as a susceptibility gene for the development of viral hepatitis-related hepatocellular carcinoma among Italian subjects.     

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.