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

Association of Vascular Endothelial Growth Factor (VEGF) and Mouse Model Minute 2 (MDM2) Polymorphisms With Diabetic Retinopathy in a Northwest Indian Population: A Case-Control Study

INTRODUCTION

Diabetic retinopathy (DR), a microvascular complication of type 2 diabetes (T2D), results from complex interactions of genetic and environmental factors. Vascular endothelial growth factor (VEGF) and mouse model minute 2 (MDM2)are upregulated in the retina due to diabetes, which increases the risk of DR. VEGFA and MDM2 genetic variations can influence DR risk. The present case-control study was conducted to evaluate the association of VEGFA and MDM2 promoter variants with DR in a population from Punjab, Northwest India.

METHODS

A total of 414 DR patients, 425 T2D patients without DR, and 402 healthy controls were screened for VEGFA -2578C/A (rs699947), VEGFA -2549I/D (rs35569394), VEGFA -7C/T (rs25648), and MDM2 rs3730485 polymorphisms using polymerase chain reaction (PCR)-based methods.

RESULTS

VEGFA -2549 I allele (OR = 1.35 (1.00-1.81), p = 0.043) and II genotype (OR = 1.78 (1.00-3.15), p = 0.047) were significantly associated with increased risk of DR. VEGFA -7 CT genotype conferred reduced risk of DR (OR = 0.28 (0.20-0.38); p = <0.001). VEGFA -2578 and MDM2 rs3730485 showed no significant association with DR. A-I-T (OR = 0.30 (0.20-0.44); p = <0.001) and C-D-T (OR = 0.33 (0.16-0.65); p = 0.002) haplotypes of rs699947-rs35569394-rs25648 polymorphisms showed decreased risk of DR.

CONCLUSIONS

I allele and II genotype of VEGFA -2549, CT genotype of VEGFA -7, and C-I-C and A-D-C haplotypes of rs699947-rs35569394-rs25648 polymorphisms were significantly associated with DR risk in a Northwest Indian population. This is the first study worldwide to report DR risk with VEGFA promoter variants together.

E7 Oncogene HPV58 Variants Detected in Northeast Brazil: Genetic and Functional Analysis

Cervical cancer is associated with persistent infections by high-risk Human Papillomavirus (HPV) types that may have nucleotide polymorphisms and, consequently, different oncogenic potentials. Therefore, this study aimed to evaluate the genetic variability and structural effects of the E7 oncogene of HPV58 in cervical scraping samples from Brazilian women. The study was developed with patients from hospitals in the metropolitan area of Recife, PE, Brazil. The most frequent HPV types were, in descending order of abundance, HPV16, 31, and 58. Phylogenetic analysis demonstrated that the isolates were classified into sublineages A2, C1, and D2. Two positively selected mutations were found in E7: 63G and 64T. The mutations G41R, G63D, and T64A in the E7 protein reduced the stability of the protein structure. Utilizing an NF-kB reporter assay, we observed a decrease in the NK-kB pathway activity with the HPV58-E7 variant 54S compared to the WT E7. The other detected E7 HPV58 variants presented similar NF-kB pathway activity compared to the WT E7. In this study, it was possible to identify mutations that may interfere with the molecular interaction between the viral oncoproteins and host proteins.

The establishment, development and future of the Chinese environmental mutagen society

It has been 40 years since the Chinese Environmental Mutagen Society (CEMS) was established in 1981. Now, it has grown a first-level national society in China, which has 15 professional committees and more than 5000 members. Over the past 40 years, the CEMS has been making many contributions to advance the research of environmental mutagens in China and cultivate professional talents in this field. In the twenty-first century, looking back on what the CEMS has gone through and accomplished, and in light of the major changes in our tasks and mission in the new era, we must plan well for the future, to overcome our shortcomings, to embrace greater development of the CEMS.

The roles and regulation of MDM2 and MDMX: it is not just about p53

In this review, Klein et al. discuss the p53-independent roles of MDM2 and MDMX. First, they review the structural and functional features of MDM2 and MDMX proteins separately and together that could be relevant to their p53-independent activities. Following this, they summarize how these two proteins are regulated and how they can function in cells that lack p53.

Most well studied as proteins that restrain the p53 tumor suppressor protein, MDM2 and MDMX have rich lives outside of their relationship to p53. There is much to learn about how these two proteins are regulated and how they can function in cells that lack p53. Regulation of MDM2 and MDMX, which takes place at the level of transcription, post-transcription, and protein modification, can be very intricate and is context-dependent. Equally complex are the myriad roles that these two proteins play in cells that lack wild-type p53; while many of these independent outcomes are consistent with oncogenic transformation, in some settings their functions could also be tumor suppressive. Since numerous small molecules that affect MDM2 and MDMX have been developed for therapeutic outcomes, most if not all designed to prevent their restraint of p53, it will be essential to understand how these diverse molecules might affect the p53-independent activities of MDM2 and MDMX.

Association of Murine Double Minute 2 Genotypes and Lung Cancer Risk

AIM

The aim of this study was to evaluate the contribution of human mouse double minute 2 (MDM2) gene polymorphisms to the risk of Taiwan lung cancer.

MATERIALS AND METHODS

In this case-control study, the association of MDM2 rs2279744 genotypes with lung cancer risk was investigated among 358 lung cancer patients and 716 age-, gender- and smoking status-matched controls in Taiwan.

RESULTS

The percentages of MDM2 rs2279744 GT and GG genotypes were 50.0% and 27.4% in lung cancer group and 50.0% and 26.5% in control group, respectively [odds ratio (OR)=1.03 and 1.07, 95% confidence interval (CI)=0.75-1.43 and 0.75-1.53, respectively]. The analysis about allelic frequency showed that G allele at MDM2 rs2279744 conferred a non-significant increased cancer risk (OR=1.03, 95%CI=0.86-1.24).

CONCLUSION

Polymorphisms of MDM2 rs2279744 may play a role in lung carcinogenesis. However, the studied genotypes were not shown as predictors of lung cancer susceptibility.

The 40bp Indel Polymorphism rs150550023 in the MDM2 Promoter is Associated with Intriguing Shifts in Gene Expression in the p53-MDM2 Regulatory Hub

Most low-penetrance genetic risk factors for cancer are located in noncoding regions, presumably altering the regulation of neighboring genes. The poorly characterized Indel polymorphism rs150550023 (rs3730485; del1518) in the promoter of MDM2 (human homolog of mouse double minute 2) is a biologically plausible candidate genetic risk factor, which might influence the expression of MDM2, a key negative regulator of the central tumor suppressor p53. Here, we genotyped rs150550023 in a Central European hospital-based case-control study of 407 breast cancer patients and 254 female controls. mRNA levels of MDM2, p53, and the p53 target genes p21, BAX, and PERP were quantified with qRT-PCR, and p53 protein was assessed with immune histochemistry in ≈100 primary breast tumors with ascertained rs150550023 genotype. We found no evidence for an association of rs150550023 with the risk, age at onset, or prognosis of breast cancer. A possible synergism was observed with SNP309 in promoter P2 of MDM2. Mean mRNA levels of MDM2, p53, p21, and BAX were ≈1.5-3 fold elevated in TP53 wildtype tumors with the minor homozygous Del/Del genotype. However, systematic shifts in p53 protein levels or mutation rates were not observed, suggesting that the elevated p53 mRNA levels are due to regulatory feedback loops that compensate for the effects of rs150550023 on MDM2 expression.

A case-control study on the SNP309T → G and 40-bp Del1518 of the MDM2 gene and a systematic review for MDM2 polymorphisms in the patients with breast cancer

Objective

The current research was conducted to study the association between the SNP309 and del1518 polymorphisms with the breast cancer in the patients with the Kurdish ethnic background from western Iran. Also, a systematic review of the relevant case‐control studies on the MDM2 polymorphisms in the patients with breast cancer was performed.

Methodology

Two mL of peripheral blood was taken from 100 patients with breast cancer and 100 healthy individuals. The frequencies of MDM2 SNP309 and del1518 genotypes and alleles were determined using the PCR‐RFLP and PCR methods, respectively.

Results

The frequency of the TT, TG, and GG of MDM2‐SNP309 genotypes in the patients was obtained as 23%, 52%, and 25%, and they were equal to 22%, 40%, and 38% in the control group, respectively. Also, considering the MDM2‐del1518 polymorphism, the frequencies of ins/ins, ins/del, and del/del genotypes were equal to 52%, 41%, and 7% in the breast cancer group and they were equal to 62, 30, and 8% in the control group, respectively. Analysis of the results indicated that the GG genotype plays a protective role for the breast cancer in the recessive model (GG vs TT + TG) of SNP309 (χ² = 3.916, P = .048, and OR = 0.54).

Conclusion

Our findings revealed that the GG genotype of MDM2‐SNP309 can play a protective role in the breast cancer disease. Also, our systematic review indicated that the SNP309, SNP285, and del1518 of MDM2 gene in different populations mostly did not have a significant association with the risk of breast cancer.

Associations between an MDM2 gene polymorphism and ulcerative colitis by ARMS-PCR

Ulcerative colitis is a form of inflammatory bowel disease characterized by chronic inflammation of the colon and rectum. The abnormal lesions in the digestive system caused by ulcerative colitis and intermittent colitis are of major clinical importance. MDM2 is a phospho-protein that functions as a ubiquitin ligase for p53. Recently, a T>G substitution in the promoter of the MDM2 gene (rs309) has been identified. In this case-control study, 174 ulcerative colitis biopsy samples and 82 control samples were collected from colonoscopy centers, hospitals, and clinics in Mazandaran and Gilan Provinces in Iran from October 2014 to May 2015. This MDM2 polymorphism was investigated in DNA samples (extracted from biopsy samples) by amplification-refractory mutation system polymerase chain reaction. The mean age of patients with ulcerative colitis was 46.5 years (range, 28 to 69 years) and that of control individuals was 45.3 years (range, 26 to 71 years). Seventy-eight patients (44.82%) were men and 96 (55.18%) were women. The distribution of the TT, TG, and GG genotypes was 17.93%, 27.59%, and 34.48%, respectively, in the ulcerative colitis patients and 31.70%, 24.40%, and 43.90%, respectively, in the control individuals (odds ratio of GG for ulcerative colitis, 7.142; 95% confidence interval, 2.400 to 9.542; p = 0.001). It was found that a single-nucleotide polymorphism at rs309 in the MDM2 gene was associated with ulcerative colitis. A direct relationship was found between age and ulcerative colitis, while no relationship was found with sex. This finding is of note because the occurrence of intestinal inflammation and subsequent ulcers can precede the development of cancer.

Association of the MDM2 SNP285 and SNP309 Genetic Variants with the Risk, Age at Onset and Prognosis of Breast Cancer in Central European Women: A Hospital-Based Case-Control Study

SNP309T>G (rs2279744) and SNP285G>C (rs117039649) in the MDM2 promoter are thought to have opposite effects on the binding of transcription factor SP1 (specificity protein 1), and consequently on MDM2 expression, p53 levels, cancer risk, age at onset, and prognosis. Here, we genotyped SNP309 and SNP285 in 406 Austrian breast cancer patients and 254 female controls. The SNP309GG genotype was associated with an increased breast cancer risk in p53 negative (OR, 1.82; 95% CI, 1.09–3.03; p = 0.02), but not p53 positive or unselected patients. In contrast, the SNP309TT genotype was associated with an earlier age at onset (TT, 57.0 ± 12.9; TG, 58.6 ± 13.9; GG, 59.7 ± 15.0 years; p = 0.048). 31% of SNP309TT, 26% of TG, and 13% of GG tumors were p53 positive (p = 0.034), indicating a lower selective pressure to mutate TP53 in the presence of the G-allele. Moreover, SNP309TT patients exhibited a shortened metastasis-free survival in multivariable analysis. Censoring carriers of the SNP285C-allele hardly altered the strength of these associations of SNP309, thus challenging the proposed antagonistic function of SNP285C towards SNP309G. The minor SNP285C-allele tended to be non-significantly associated with an increased breast cancer risk and a poor disease-free and metastasis-free survival, which may be bystander effects of its complete linkage disequilibrium with SNP309G. We conclude that the SNP309G-allele attenuates the p53-response and leads to a higher breast cancer risk, but also to a later onset of breast cancer and a trend towards a good prognosis.

Contribution of Murine Double Minute 2 Genotypes to Colorectal Cancer Risk in Taiwan

BACKGROUND/AIM

The genomic role of human mouse double minute 2 (MDM2) in colorectal cancer (CRC) is unclear, therefore, our study aimed to evaluate the contribution of MDM2 genotype to the risk of CRC in Taiwan.

MATERIALS AND METHODS

In this case-control study, MDM2 SNP309 T to G (rs2279744) genotypes were determined and their association with CRC risk were investigated among 362 patients with CRC and 362 age- and gender-matched healthy controls in central Taiwan. In addition, the interaction of MDM2 SNP309 genotypes with personal behaviors and clinicopathological features were also examined.

RESULTS

The percentage of variant GG for the MDM2 SNP309 genotype was 30.9% in the CRC group and 24.0% in the control group, respectively (odds ratio (OR)=1.78, 95% confidence interval (CI)=1.25-2.86, p=0.0057). The allelic frequency distribution analysis showed that the variant G allele of MDM2 SNP309 conferred a significantly increased susceptibility to CRC compared with the wild-type T allele (OR=1.32, 95% CI=1.14-1.69, p=0.0062). As for the gene-lifestyle interaction, there was an obvious joint effect of MDM2 SNP309 GG genotype on the risk of CRC among ever-smokers and non-alcohol drinkers, but not non-smoker or alcohol drinker subgroups. No statistically significant correlation was observed between MDM2 SNP309 genotypic distributions and age, gender, tumor size, location or metastasis status.

CONCLUSION

The genotypes of MDM2 SNP309 may allow forr early detection of and predictor for CRC risk, especially among smokers and non-alcohol drinkers, but not for prognosis. The combined effects of MDM2 SNP309 and other genes (such as matrix metalloproteinases) on CRC susceptibility and prognosis, should also be taken into consideration in the era of precision medicine.

Associations between the MDM2 promoter P1 polymorphism del1518 (rs3730485) and incidence of cancer of the breast, lung, colon and prostate

The MDM2 promoter region contains several polymorphisms, some of which have been associated with MDM2 expression, cancer risk and age at cancer onset. del1518 (rs3730485) is an indel polymorphism residing in the MDM2 promoter P1 and is in almost complete linkage disequilibrium with the MDM2 promoter P2 polymorphism SNP309T>G (rs2279744). Cancer risk assessments of del1518 have previously been conducted in relatively small Chinese populations only. In this study we assessed the genotype distribution of del1518 among healthy Caucasians, African Americans and Chinese, and we estimated the Odds Ratios (OR) for incident cancer of the breast, colon, lung and prostate (n=7,081) as compared to controls (n=3,749) in a large Caucasian (Norwegian) cohort.We found the genotypes of the del1518 to vary significantly between healthy Caucasians, African-Americans and Chinese (p< 1×10-5). Further, we found a positive association of the del1518 del-allele with risk of colon cancer (dominant model: OR = 1.15; 95 % CI = 1.01 - 1.31). Stratifying according to SNP309 status, this association remained among carriers of the SNP309TG genotype (OR = 1.21; 95 % CI = 1.01 - 1.46), but with no clear association among carriers of the SNP309TT genotype. In conclusion, our findings suggest del1518 to be associated with increased risk of colon cancer.

Association of p73 gene G4C14-A4T14 polymorphism and MDM2 gene SNP309 with non-small cell lung cancer risk in a Chinese population

The present study aimed to investigate the association of p73 G4C14-A4T14 polymorphism and murine double minute 2 (MDM2) 309 T/G single nucleotide polymorphisms (SNPs) with the risk of developing non-small cell lung cancer (NSCLC) in Sothern China. The p73 and MDM2 genotypes of peripheral blood DNA from 186 patients with NSCLC and 196 normal controls were detected by polymerase chain reaction (PCR) with confronting two-pair primers (CTPP) and high resolution melting (HRM), respectively. The results of genotyping were consistent with those of direct sequencing. The p73 AT/AT [odds ratio (OR)=0.46; 95% confidence interval (CI)=0.22-0.97] and MDM2 TT (OR=0.48; 95% CI=0.26-0.86) genotypes were associated with a decreased risk of developing NSCLC compared with that of the p73 GC/GC and MDM2 GG genotypes, respectively. In addition, the interaction between the p73 and MDM2 polymorphisms reduced the risk of developing NSCLC in multiple ways (OR=0.13; 95% CI=0.03-0.59) for subjects carrying both the p73 AT/AT and MDM2 TT genotypes. Therefore, the SNP in p73 G4C14-A4T14 and the MDM2 309 polymorphism may be markers of genetic susceptibility to NSCLC in a Chinese population, and there is a possible gene-gene interaction involved in the incidence of NSCLC.

Association between polymorphisms in TP53 and MDM2 genes and susceptibility to prostate cancer

Tumor protein 53 (TP53), a tumor suppressor gene, is a vital cellular cancer suppressor in multicellular organisms. Murine double minute-2 (MDM2) is an oncoprotein that inhibits TP53 activity. A number of studies have examined the association of TP53 and MDM2 polymorphisms with the risk of common forms of cancer, but the findings remain inconclusive. The present study aimed to evaluate the impact of the 40-bp insertion/deletion (I/D) polymorphism (rs3730485) in the MDM2 promoter region and the 16-bp I/D polymorphism (rs17878362) in TP53 on the susceptibility of prostate cancer (PCa) in a sample of the Iranian population. This case-control study included 103 patients with pathologically confirmed PCa and 142 patients with benign prostatic hyperplasia. The MDM2 40-bp I/D and TP53 16-bp I/D polymorphism was determined using polymerase chain reaction analysis. The results demonstrated that the MDM2 40-bp I/D polymorphism increased the risk of PCa in a co-dominant inheritance model [odds ratio (OR)=1.88; 95% confidence interval (CI)=1.11-3.19; P=0.023, D/D vs. I/I], while this variant marginally increased the risk of PCa in a dominant model (OR=1.69; 95% CI=1.00-2.83; P=0.051, I/D+D/D vs. I/I). No significant association was observed between the TP53 16-bp I/D polymorphism and PCa. In conclusion, the present study demonstrated that the 40-bp I/D polymorphism in the MDM2 promoter increased the risk of PCa in an Iranian population. Further investigations with diverse ethnicities and larger sample sizes are required to verify these results.

MDM2 promoter polymorphism del1518 (rs3730485) and its impact on endometrial and ovarian cancer risk

Background

The del1518 (rs3730485) polymorphism is an in/del variant in the MDM2 promoter P1. The variant is in complete linkage disequilibrium with MDM2 SNP309 (rs2279744) and has previously been found associated with an increased risk of colon cancer. In this study we assessed the impact of MDM2 del1518 on risk of ovarian and endometrial cancer.

Methods

Here, we genotyped del1518 in two large hospital-based series of patients diagnosed with ovarian (n = 1,385) or endometrial (n = 1,404) cancer and performed risk estimations as compared to the genotype distribution among 1,872 healthy female controls.

Results

In overall analysis we observed no association between del1518 and risk of either ovarian or endometrial cancer. However, stratifying according to SNP309 status, we found the del1518 variant to be associated with a reduced risk of endometrial cancer among individuals carrying the SNP309TT genotype both in the dominant (OR = 0.64; 95% CI = 0.45 – 0.90) and the recessive model (OR = 0.80; 95% CI = 0.65 – 1.00). No such association was observed for ovarian cancer risk.

Conclusion

We found the MDM2 del1518 del variant to be associated with reduced risk of endometrial cancer among individuals carrying the MDM2 SNP309TT genotype.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-017-3094-y) contains supplementary material, which is available to authorized users.

MDM2 gene polymorphisms and risk of classic Kaposi's sarcoma among Iranian patients

A single-nucleotide polymorphism (SNP) in the promoter region of MDM2 (SNP309T>G, rs2279744) has been shown to increase the expression of the MDM2 protein in various cancer types. However, only one study has analyzed the role of the MDM2 polymorphism in the development of Kaposi's sarcoma (KS). The association of MDM2 SNP309 with classic KS risk was evaluated in 79 Iranian patients with classic KS and 123 healthy controls. The MDM2 SNP309 was genotyped using PCR and restriction fragment length polymorphism methods. No significant correlation was found between the SNP309 polymorphism in MDM2 promoter and classic KS risk. There was no significant correlation between gender and disease stage. However, a significant association was found between SNP309 GG genotype and younger age (≤50 years) (odds ratio 9.5, 95% confidence intervals 1.5-60, p = 0.03). Our findings support no major role for the MDM2 SNP309 in KS development although it might influence the clinical outcome of KS in younger patients.

MDM2 promoter del1518 polymorphism and cancer risk: evidence from 22,931 subjects

Studies have shown that single-nucleotide polymorphisms in MDM2 gene may play important roles in the development of malignant tumor. The association of del1518 polymorphism (rs3730485) in the MDM2 promoter with cancer susceptibility has been extensively studied; however, the results are contradictory. To quantify the association between this polymorphism and overall cancer risk, we conducted a meta-analysis with 12,905 cases and 10,026 controls from 16 eligible studies retrieved from PubMed, Embase, and Chinese Biomedical (CBM) databases. We assessed the strength of the connection using odds ratios (ORs) and 95% confidence intervals (CIs). In summary, no significant associations were discovered between the del1518 polymorphism and overall cancer risk (Del/Del vs Ins/Ins: OR =1.01, 95% CI =0.90-1.14; Ins/Del vs Ins/Ins: OR =1.03, 95% CI =0.96-1.12; recessive model: OR =0.98, 95% CI =0.90-1.07; dominant model: OR =1.03, 95% CI =0.94-1.12; and Del vs Ins: OR =1.01, 95% CI =0.94-1.07). In the stratified analysis by source of control, quality score, cancer type, and ethnicity, no significant associations were found. Despite some limitations, the current meta-analysis provides solid statistical evidence of lacking association between the MDM2 del1518 polymorphism and cancer risk.

Clinical significance of TP53 (R72P) and MDM2 (T309G) polymorphisms in breast cancer patients

INTRODUCTION

TP53 gene is the most frequently altered tumor suppressor gene in breast cancer. It has been observed that MDM2 plays a central role in regulating the TP53 pathway. This study aimed to investigate the role of TP53 Arg72Pro and MDM2 T309G polymorphisms in breast cancer patients.

MATERIAL AND METHOD

The TP53 (Arg72Pro) and MDM2 (T309G) polymorphisms were studied in a hospital-based case control study by AS-PCR in 100 breast cancer patients and 100 healthy control subjects.

RESULTS

It was observed that TP53 Arg72Pro polymorphism was significantly associated with breast cancer (χ (2) = 9.92, p = 0.007). A significantly increased breast cancer risk was associated with the Proline allele [odds ratio 1.84 (95 % CI: 1.22-2.77), risk ratio 1.34 (95 % CI: 1.11-1.63), p value 0.003], HER2/neu status (p = 0.01) and distant metastasis (p = 0.05). On the other hand, we have found a significant correlation between MDM2 (T309G) polymorphism with HER2/neu status (χ (2) = 11.14, p = 0.003) and distant metastasis (p value = 0.04).

CONCLUSION

Our finding suggests that TP53 (Arg72Pro) polymorphism may play a significant role as risk factor for breast cancer in north Indian breast cancer patients. While MDM2 (T309G) polymorphism may not be directly associated with the risk of breast cancer occurrence in the same population, but it may play role in disease progression by triggering TP53.

A 40-bp insertion/deletion polymorphism of Murine Double Minute2 (MDM2) increased the risk of breast cancer in Zahedan, Southeast Iran

Background: MDM2 (Murine Double Minute2) is an oncoprotein that inhibits the P53 activity. Overexpression of MDM2 gene has been reported in several human tumors. In the present study, we aimed to evaluate the impact of 40-bp insertion/deletion (ins/del) polymorphism on the promoter of MDM2 and susceptibility to breast cancer in a sample of Iranian population. Methods: This case-control study was carried out on 236 patients with breast cancer and 203 healthy individuals. Genomic DNA was extracted from the whole blood by the salting-out method. The 40-bp ins/del polymorphism was determined by using polymerase chain reaction. Results: The findings indicated that MDM2 ins/del variant increased the risk of breast cancer in co-dominant- (odds ratio [OR] = 2.09, 95% CI = 1.14-3.85, P = 0.018, del/del vs. ins/ins), dominant- (OR = 1.49, 95% CI = 1.02-2.18, P = 0.038, ins/del + del/del vs. ins/ins), and recessive- (OR = 1.86, 95% CI = 1.03-3.34, P = 0.038, del/del vs. ins/ins + ins/del) tested inheritance models. The del allele increased the risk of breast cancer (OR = 1.48, 95% CI = 1.11-1.98, P = 0.008) compared with ins allele. Conclusions: Our result revealed that 40-bp ins/del polymorphism in the promoter of MDM2 increased the risk of breast cancer in an Iranian population. Further investigations with larger sample sizes and diverse ethnicities are needed to verify our findings.

MDM2 polymorphism associated with the development of cervical lesions in women infected with Human papillomavirus and using of oral contraceptives

Background

The MDM2 gene is the major negative regulator of p53, a tumor suppressor protein. Single nucleotide polymorphism in promoter region of MDM2 gene leads to increased expression resulting in higher levels of MDM2 protein. This event increases the attenuation of the p53 pathway. Polymorphisms in this gene can interfere in the regulation of cellular proliferation. We evaluated whether MDM2 SNP309 (rs2278744) associated or not with the use of oral contraceptive can heighten susceptibility to development of cervical lesions in women HPV infected.

Methods

MDM2 SNP309 (rs2278744) was genotyped in a total of 287 patients using the PCR-RFLP technique. The results were analyzed by UNPHASED v.3.121 and SNPStats programs.

Results

The three groups (SIL, LSIL and HSIL) showed no significant differences in either genotype or allelic frequencies for MDM2 polymorphisms, except when HSIL was compared with LSIL (p = 0.037; OR = 1.81). Furthermore, in the analysis of contraceptives, a significant association was found between the use of contraceptives and the MDM2 variant in the development of high-grade cervical lesions for the TG genotype (p = 0.019; OR = 2.21) when HSIL was compared with control. When HSIL was compared with LSIL (p = 0.006; OR = 2.27).

Conclusion

The results of this study suggest that MDM2 SNP309 might be a good marker for assessing the progression of LSIL to HSIL. In addition, they also show that oral contraceptives alone, did not have any effect on the progression or development of cervical lesions. However, they may act synergistically with MDM2 SNP309 (rs2278744) and HPV infection in the development of cervical lesions.

MDM2 SNP309 polymorphism is associated with colorectal cancer risk

The human murine double minute 2 (MDM2) is known as an oncoprotein through inhibiting P53 transcriptional activity and mediating P53 ubiquitination. Therefore, the amplification of MDM2 may attenuate the P53 pathway and promote tumorigenesis. The SNP309 T>G polymorphism (rs2279744), which is located in the intronic promoter of MDM2 gene, was reported to contribute to the increased level of MDM2 protein. In this hospital-based case-control study, which consisted of 573 cases and 588 controls, we evaluated the association between MDM2 SNP309 and the risk of colorectal cancer (CRC) in a Chinese population by using the TaqMan method to genotype the polymorphism. We found that the MDM2 SNP309 polymorphism was significantly associated with CRC risk. In addition, in our meta-analysis, we found a significant association between MDM2 SNP309 and CRC risk among Asians, which was consistent with our results. In conclusion, we demonstrated that the MDM2 SNP309 polymorphism increased the susceptibility of CRC in Asian populations.

Association between MDM2 rs 2279744 polymorphism and breast cancer susceptibility: a meta-analysis based on 9,788 cases and 11,195 controls

Purpose

Previous studies have suggested associations between MDM2 (mouse double minute 2 homolog) polymorphisms and cancer risk. The aim of this study was to evaluate the relationship between the MDM2 rs 2279744 polymorphism and the susceptibility of breast cancer.

Methods

We searched PubMed, Web of Knowledge, Embase, and the Chinese National Knowledge Infrastructure (CNKI) database for case–control studies published up to October 2013 that investigated MDM2 rs 2279744 polymorphism and breast cancer risk. Odds ratios (ORs) and 95% confidence intervals (CIs) were used to assess the strength of these associations.

Results

A total of 19 studies were identified for the meta-analysis, including 9,788 cases and 11,195 controls. The variant heterozygote (TG) was associated with breast cancer risk in the overall population (TG vs TT: OR =1.10, 95% CI =1.04–1.17, P=0.001, P=0.23 for heterogeneity test). In the subgroup analyses by ethnicity, a significantly increased risk was observed among Asians (G vs T: OR =1.12, 95% CI =1.02–1.23, P=0.02, P_het=0.04; GG vs TT: OR =1.29, 95% CI =1.06–1.56, P=0.01, P_het=0.04; TG vs TT: OR =1.36, 95% CI =1.15–1.60, P=0.0004, P_het=0.45; dominant model TG+GG vs TT: OR =1.21, 95% CI =1.03–1.41, P=0.02, P_het=0.07). However, among Caucasians, rs 2279744 was associated with breast cancer risk in only one genotype (TG vs TT: OR =1.09, 95% CI =1.00–1.18, P=0.04, P_het=0.37). No publication bias was found in the present study.

Conclusion

This meta-analysis provides evidence for the association between the MDM2 rs 2279744 polymorphism and breast cancer susceptibility. The results suggest that the MDM2 rs 2279744 polymorphism plays an important role in breast cancer, especially in Asians.

Meta-analysis of associations between the MDM2-T309G polymorphism and prostate cancer risk

The mouse double minute 2 (MDM2) gene plays a key role in the p53 pathway, and the SNP 309T/G single- nucleotide polymorphism in the promoter region of MDM2 has been shown to be associated with increased risk of cancer. However, no consistent results were found concerning the relationships between the polymorphism and prostate cancer risk. This meta-analysis, covering 4 independent case-control studies, was conducted to better understand the association between MDM2-SNP T309G and prostate cancer risk focusing on overall and subgroup aspects. The analysis revealed, no matter what kind of genetic model was used, no significant association between MDM2-SNP T309G and prostate cancer risk in overall analysis (GT/TT: OR = 0.84, 95%CI = 0.60-1.19; GG/TT: OR = 0.69, 95%CI = 0.43-1.11; dominant model: OR = 0.81, 95%CI= 0.58-1.13; recessive model: OR = 1.23, 95%CI = 0.95-1.59). In subgroup analysis, the polymorphism seemed more likely to be a protective factor in Europeans (GG/TT: OR = 0.52, 95%CI = 0.31-0.87; recessive model: OR = 0.58, 95%CI = 0.36-0.95) than in Asian populations, and a protective effect of the polymorphism was also seen in hospital-based studies in all models (GT/TT: OR = 0.74, 95%CI = 0.57-0.97; GG/TT: OR = 0.55, 95%CI = 0.38-0.79; dominant model: OR = 0.69, 95%CI = 0.54-0.89; recessive model: OR = 0.70, 95%CI = 0.51-0.97). However, more primary studies with a larger number of samples are required to confirm our findings.

Effect of the MDM2 promoter polymorphisms SNP309T>G and SNP285G>C on the risk of ovarian cancer in BRCA1 mutation carriers

Background

While BRCA mutation carriers possess a 20-40% lifetime risk of developing ovarian cancer, knowledge about genetic modifying factors influencing the phenotypic expression remains obscure. We explored the distribution of the MDM2 polymorphisms SNP309T>G and the recently discovered SNP285G>C in Norwegian patients with BRCA related ovarian cancer.

Methods

221 BRCA related ovarian cancer cases (BRCA1; n = 161 and BRCA2; n = 60) were tested for the MDM2 polymorphisms. Results were compared to healthy controls (n = 2,465).

Results

The SNP309G allele was associated with elevated OR for ovarian cancer in BRCA1 mutation carriers (SNP309TG: OR 1.53; CI 1.07-2.19; p = 0.020; SNP309GG: OR 1.92; CI 1.19-3.10; p = 0.009; SNP309TG+GG combined: OR 1.61; CI 1.15-2.27; p = 0.005). In contrast, the SNP285C allele reduced risk of BRCA1 related ovarian cancer in carriers of the SNP309G allele (OR 0.50; CI 0.24-1.04; p = 0.057). Censoring individuals carrying the SNP285C/309G haplotype from the analysis elevated the OR related to the SNP309G allele (OR 1.73; CI 1.23-2.45; p = 0.002). The mean age at disease onset was 3.1 years earlier in carriers of SNP309TG+GG as compared to carriers of SNP309TT (p = 0.068). No such associations were found in BRCA2 related ovarian cancer.

Conclusions

Our results indicate the SNP309G allele to increase and the SNP285C allele to reduce the risk of BRCA1 related ovarian cancer. If confirmed in independent studies, this finding may have implications to counseling and decision-making regarding risk reducing measures in BRCA1 mutation carriers.

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.

MDM2 SNP309T>G polymorphism increases susceptibility to hepatitis B virus-related hepatocellular carcinoma in a northeast Han Chinese population

BACKGROUND AND AIMS

The murine double minute 2 (MDM2) gene encodes a negative regulator of the tumour protein p53. A single nucleotide polymorphism (SNP) in MDM2 promoter, SNP309 T > G, has been showed to influence MDM2 protein expression and accelerate tumour formation. To investigate further the role of this locus, we examined the association of the SNP with hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC) in a northeast Han Chinese population.

METHODS

MDM2 SNP309 was genotyped in 310 HBV-related HCC patients, 314 non-HCC subjects with HBV infection and 480 healthy controls by using a PCR-RFLP method.

RESULTS

Significant differences of MDM2 SNP309 were detected between HBV-related HCC patients and healthy controls (OR 1.729, 95%CI 1.369-2.183, P < 0.0001) or non-HCC subjects with HBV infection (OR 1.351, 95% CI 1.060-1.722, P = 0.015) by a logistic regression analysis. Our data also revealed that subjects with the G allele had higher HBV-related HCC susceptibility than those with the T allele in various genetic models. In a meta-analysis, where we pooled our data with other published studies, the association between this loci and the disease was further confirmed (pooled OR 1.54, 95% CI 1.37-1.72, P < 0.0001).

CONCLUSIONS

These results suggested that the MDM2 SNP309 might influence the risk of developing HBV-related HCC in a northeast Han Chinese population.

Murine double minute clone 2,309T/G and 285G/C promoter single nucleotide polymorphism as a risk factor for breast cancer: a Polish experience

BACKGROUND

Breast cancer is a multifactorial disease caused by complex interactions between genetic and environmental factors. Recently, a functional polymorphism, MDM2 285G>C (rs117039649), has been discovered. This polymorphism antagonizes the effect of the 309T>G (rs2279744) polymorphism on the same gene, resulting in decreased MDM2 transcription.

METHODS

The MDM2 285G>C and 309T>G polymorphisms were identified by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and sequencing analysis in women with breast cancer (n=468) and controls (n=550).

RESULTS

The odds ratio (OR) for breast cancer patients with the MDM2 285C/C and 285G/C genotypes was 0.4768 (95% confidence interval [CI] 0.2906-0.7824; p=0.0033, pcorr=0.0066). We also found a significantly lower frequency of the MDM2 285C allele in patients with breast cancer than in controls: the OR for the C allele in patients with breast cancer was 0.4930 (95% CI=0.3059-0.7947, p=0.0031, pcorr=0.0062). The p value of the chi-square test for the trend observed for the MDM2 285G>C polymorphism was statistically significant (ptrend=0.0036). The statistical power of this study amounted to 85% for the G/C or C/C genotypes and 85% for the C allele. However, we did not observe significant differences between the distribution of MDM2 309T>G genotypes and alleles in patients with breast cancer and healthy controls.

CONCLUSION

In a sample of the Polish population, we observed that the MDM2 285C gene variant may be a significant protective factor against breast cancer.

Individual and combined effects of MDM2 SNP309 and TP53 Arg72Pro on breast cancer risk: an updated meta-analysis

The tumor suppressor gene TP53 and its negative regulator murine double minute 2 are involved in multiple cellular pathways. Two potentially functional single nucleotide polymorphisms (SNPs) MDM2 SNP309 and TP53 R72P have been extensively investigated to be associated with breast cancer risk. However, the original studies as well as the subsequent meta-analysis, have yielded contradictory results for the individual effect of the two SNPs on breast cancer risk, plus that conflicting results also existed for the combined effects of MDM2 SNP309 and TP53 R72P on breast cancer risk. This meta-analysis aimed to clarify the individual and combined effects of these two genes on breast cancer risk. We performed a meta-analysis of publications with a total 9,563 cases and 9,468 controls concerning MDM2 SNP309 polymorphism and 19,748 cases and 19,962 controls concerning TP53 R72P. Odds ratios (ORs) with 95 % confidence intervals (CIs) were used to assess the strength of the association. In overall meta-analysis, individuals with the MDM2 SNP309TG genotype were associated with a borderline higher breast cancer risk than those with TT genotype (OR = 1.11, 95 % CI: 1.00-1.24, P (heterogeneity) = 0.007), whereas the TP53 R72P CC or GC genotype had no effects on breast cancer risk. In the stratified analyses, a significant association between MDM2 SNP309 and breast cancer risk were observed in Asian, but null significant association between TP53 R72P and breast cancer risk were found even in various subgroups. Moreover, no significant combined effects of MDM2 SNP309 and TP53 R72P were observed on breast cancer risk. The borderline association between MDM2 SNP309 and breast cancer risk in overall analysis should be treated with caution, and no significant combined effects for the two SNPs on breast cancer risk suggested functional investigations warranted to explore the molecular mechanism of the TP53-MDM2 circuit genes.

Association of genetic polymorphisms in MDM2, PTEN and P53 with risk of esophageal squamous cell carcinoma

Genetic variations in MDM2, PTEN and P53 might be involved in cancer susceptibility. To assess the contribution of polymorphisms in these three genes to the risk of esophageal squamous cell carcinoma (ESCC) in a Chinese population, we genotyped MDM2 T309G, Del1518, PTEN rs701848, rs2735343 and P53 Arg72Pro polymorphisms using PCR-restriction fragment length polymorphism analysis in 226 ESCC cases and 226 cancer-free controls. Here we showed that the risk of ESCC was elevated in subjects with any of the variant genotypes of PTEN rs2735343 and P53 Arg72Pro polymorphisms, but not any genotype of MDM2 or PTEN rs701848. Moreover, multiplicative interactions were observed between PTEN rs2735343 and P53 Arg72Pro or smoking status on risk of ESCC. Our study firstly indicated that PTEN rs2735343 might be a susceptibility factor for ESCC and reaffirmed the role of P53 Arg72Pro in ESCC in this Chinese population, but did not replicate the positive association between MDM2 T309G and ESCC found previously.

A 40-bp insertion/deletion polymorphism in the constitutive promoter of MDM2 confers risk for hepatocellular carcinoma in a Chinese population

The pathogenesis of HCC is a multistage process with the involvement of genetic factors. The aim of the present study is to investigate the possible association between a 40-bp insertion/deletion polymorphism (indel) at constitutive promoter of MDM2 and risk of hepatocellular carcinoma (HCC) in a Chinese population. Using 420 HCC patients and 423 control subjects, we genotyped the indel polymorphism (rs3730485) using polymerase chain reaction method. Logistic regression was used to analyze the association between the polymorphism and HCC susceptibility. Under co-dominant model, we found that the ins/del and del/del genotype of indel was associated with a significantly increased risk of HCC compared with its homozygote ins/ins (OR=1.39, 95%C.I.=1.03-1.87; OR=1.68, 95%C.I.=1.03-2.73, respectively). Presence of 40-bp deletion allele of MDM2 seemed to confer higher risk for HCC when compared with non-carriers (OR=1.30, 95%C.I.=1.06-1.60, P=0.011). Further stratification analysis showed that this association was more pronounced in patients with a family history of HCC, early tumor stage and higher serum alpha-fetoprotein (AFP). These findings indicated that the MDM2 indel polymorphism may be a genetic modifier for developing HCC in Chinese population.

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

BACKGROUND AND AIMS

The murine double minute 2 (MDM2) gene encodes a negative regulator of the tumor protein p53. A single nucleotide polymorphism (SNP) in MDM2 promoter, SNP309 T>G, has been reported to alter MDM2 protein expression and accelerate tumor formation in humans. Studies investigating the association between the polymorphism and human hepatocellular carcinoma (HCC) risk reported conflicting results. We performed a meta-analysis to explore the association of this polymorphism and HCC risk.

METHODS

All eligible studies published were searched for in PubMed. Crude odds ratios (ORs) with 95% confidence intervals (CIs) were assessed for the association using fixed- and random-effects models.

RESULTS

We identified five case-control studies including 738 cases and 1014 controls for the present meta-analysis. In studies with limited data, we detected significant associations for all genetic models in the overall analysis (OR = 2.51, 95% CI = 1.88-3.36 for GG vs. TT, p <0.001, P(het) = 0.666; OR = 1.71, 95% CI = 1.35-2.18 for TG vs. TT, p <0.001, P(het) = 0.925; OR = 1.94, 95% CI = 1.54-2.43 for dominant model TG + GG vs. TT, p <0.001, P(het) = 0.772; OR = 1.74, 95% CI = 1.39-2.20 for recessive model GG vs. TT + TG, p <0.001, P(het) = 0.656). Moreover, in the subgroup analysis based on Hardy-Weinberg equilibrium (HWE) in controls, sample size, and ethnicity, significant associations were observed in most genetic models.

CONCLUSIONS

This meta-analysis suggests that the MDM2 309 G allele probably acts as an important HCC risk factor. To further confirm our findings, well-designed studies with large sample sizes and representing different ethnicities are required.

Involvement of single-nucleotide polymorphisms in predisposition to head and neck cancer in Saudi Arabia

AIM

Individuals differ in their inherited tendency to develop cancer. This has been suggested to be due to genetic variations between individuals. Single-nucleotide polymorphisms (SNPs) are the most common form of genetic variations found in the human population. The aim of this study was to investigate the association between 10 SNPs in genes involved in cell cycle control and DNA repair (p21 C31A, p53 G72C, ATM G1853A, XRCC1 G399A, XRCC3 C241T, Ku80 A2790G, DNA Ligase IV C9T, DNA-PKcs A3434G, TGF-beta T10C, MDM2 promoter T309G) and the risk to develop head and neck cancer.

MATERIALS AND METHODS

A cohort of 407 individuals (156 cancer patients and 251 controls) was included. DNA was extracted from peripheral blood. SNPs were genotyped by direct sequencing.

RESULTS

Data showed significant allelic associations for p21 C31A (p=0.04; odds ratio [OR]=1.44; confidence interval [CI]: 1.02-2.03), Ku80 A2790G (p=0.04; OR=1.5; CI: 1.01-2.23), and MDM2 T309G (p=0.0003; OR=0.58; CI: 0.43-0.78) and head and neck cancer occurrence. Both cancer cases and controls were in Hardy-Weinberg equilibrium.

CONCLUSION

SNPs can be associated with head and neck cancer in the Saudi population. The p21 C31A, Ku80 A2790G, and MDM2 T309G SNPs could be used as genetic biomarkers to screen individuals at high cancer risk.

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.

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.

Lysyl oxidase 473 G>A polymorphism and breast cancer susceptibility in Chinese Han population

Lysyl oxidase (LOX) is an extracellular enzyme critical for the cross-linking of collagens and elastin. The LOX gene has also been shown to inhibit the transforming activity of Ras oncogene signaling. Recently, a single-nucleotide polymorphism (SNP) of LOX G473A (rs1800449) has been demonstrated to be associated with increased risk of breast cancer in African American women. In this hospital-based case-control study, the association of LOX polymorphism with breast cancer susceptibility in Chinese Han population was investigated. In total, 238 female patients with breast cancer and 234 age-matched healthy controls recruited were genotyped. We found a significant difference in the frequency of the LOX G473A genotype between the breast cancer and control groups. Individuals with GA genotype showed a 2.79-fold (95% confidence interval = 1.87-4.16) increased risk of breast cancer compared with subjects carrying GG genotype (p < 0.001). Further statistical analysis revealed that this polymorphism was an independent parameter with regard to other variables that are significantly associated with breast cancer, that is, age, menopausal status, estrogen exposure interval, expression status of estrogen receptor, and progesterone receptor. These findings suggest that the LOX 473 GA genotype is independently associated with increased risk of breast cancer in Chinese female population.

MDM2 promoter polymorphism is associated with increased susceptibility to hepatocellular carcinoma in Turkish population

BACKGROUND

The mouse double minute 2 (MDM2) gene represents one of the central nodes in the p53 pathway. A naturally occurring T/G single nucleotide polymorphism (SNP) in the intronic promoter of MDM2, SNP309 (rs2279744), was shown to influence MDM2 expression and p53 activity. SNP in the promoter region of MDM2 gene has recently been shown to be associated with accelerated tumor formation in both hereditary and sporadic cancers in humans. In this study, we aim to evaluate the association of SNP309 with the risk of hepatocellular carcinoma (HCC) development among Turkish population.

METHODS

MDM2 SNP309 polymorphism was investigated in 110 confirmed subjects with HCC and 110 cancer-free control subjects matched on age, gender, smoking and alcohol consumption by using a polymerase chain reaction-restriction fragment length polymorphism assay.

RESULTS

The allele frequencies of case subjects (T, 0.48; G, 0.52) were significantly different from those of control subjects (T, 0.65; G, 0.35) (p=0.003). The proportion of GG genotype of the SNP309 in patients with HCC (26%) was significantly higher than that in patients without HCC (14%). We observed that compared with the TT genotype, the genotypes containing G allele [TG (OR, 2.19; 95% CI, 1.18-4.07; p=0.013) or GG (OR, 3.63; 95% CI, 1.65-8.00; p=0.001)] were associated with significant increased susceptibility to HCC.

CONCLUSION

Our findings suggest that the MDM2 promoter SNP309 G allele is associated with presence of HCC in Turkish population.

Association between MDM2-SNP309 and hepatocellular carcinoma in Taiwanese population

AIM: To investigate the risk association and compare the onset age of hepatocellular carcinoma (HCC) patients in Taiwan with different genotypes of MDM2-SNP309.

METHODS: We analyzed MDM2-SNP309 genotypes from 58 patients with HCC and 138 cancer-free healthy controls consecutively. Genotyping of MDM2-SNP309 was conducted by restriction fragment length polymorphism assay.

RESULTS: The proportion of homozygous MDM2-SNP309 genotype (G/G) in cases and cancer-free healthy controls was similar (17.2% vs 16.7%). Multivariate analysis showed that the risk of G/G genotype of MDM2-SNP309 vs wild-type T/T genotype in patients with HCC was not significant (OR = 1.265, 95% CI = 0.074-21.77) after adjustment for sex, hepatitis B or C virus infection, age, and cardiovascular disease/diabetes. Nevertheless, there was a trend that GG genotype of MDM2-SNP309 might increase the risk in HCC patients infected with hepatitis virus (OR = 2.568, 95% CI = 0.054-121.69). Besides, the homozygous MDM2-SNP309 genotype did not exhibit a significantly earlier age of onset for HCC.

CONCLUSION: Current data suggest that the association between MDM2-SNP309 GG genotype and HCC is not significant, while the risk may be enhanced in patients infected by hepatitis virus in Taiwan.

Winter temperature and UV are tightly linked to genetic changes in the p53 tumor suppressor pathway in Eastern Asia

The tumor suppressor p53 is a master sensor of stress. Two human-specific polymorphisms, p53 codon 72 and MDM2 SNP309, influence the activities of p53. There is a tight association between cold winter temperature and p53 Arg72 and between low UV intensity and MDM2 SNP309 G/G in a cohort of 4029 individuals across Eastern Asia that suggests causative selection. Moreover, the two polymorphisms are not coselected. Haplotype-based selection analysis further suggests that this is a striking example of two functional polymorphisms being strongly selected for in human populations in response to environmental stresses.

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.

Results based on 124 cases of breast cancer and 97 controls from Taiwan suggest that the single nucleotide polymorphism (SNP309) in the MDM2 gene promoter is associated with earlier onset and increased risk of breast cancer

Background

It has been suggested that the single nucleotide polymorphism 309 (SNP309, T -> G) in the promoter region of the MDM2 gene is important for tumor development; however, with regards to breast cancer, inconsistent associations have been reported worldwide. It is speculated that these conflicting results may have arisen due to different patient subgroups and ethnicities studied. For the first time, this study explores the effect of the MDM2 SNP309 genotype on Taiwanese breast cancer patients.

Methods

Genomic DNA was obtained from the whole blood of 124 breast cancer patients and 97 cancer-free healthy women living in Taiwan. MDM2 SNP309 genotyping was carried out by restriction fragment length polymorphism (RFLP) assay. The multivariate logistic regression and the Kaplan-Meier method were used for analyzing the risk association and significance of age at diagnosis among different MDM2 SNP309 genotypes, respectively.

Results

Compared to the TT genotype, an increased risk association with breast cancer was apparent for the GG genotype (OR = 3.05, 95% CI = 1.04 to 8.95), and for the TG genotype (OR = 2.12, 95% CI = 0.90 to 5.00) after adjusting for age, cardiovascular disease/diabetes, oral contraceptive usage, and body mass index, which exhibits significant difference between cases and controls. Furthermore, the average ages at diagnosis for breast cancer patients were 53.6, 52 and 47 years for those harboring TT, TG and GG genotypes, respectively. A significant difference in median age of onset for breast cancer between GG and TT+TG genotypes was obtained by the log-rank test (p = 0.0067).

Conclusion

Findings based on the current sample size suggest that the MDM2 SNP309 GG genotype may be associated with both the risk of breast cancer and an earlier age of onset in Taiwanese women.

Establishment and characterization of three new human breast cancer cell lines derived from Chinese breast cancer tissues

BACKGROUND

Breast cancer is a major malignancy affecting females worldwide. It is the most common cause of death from cancer in women. Cell lines are widely used in laboratory research and particularly as in vitro models in cancer research. But we found that the routinely used breast cancer cell lines were mostly derived from Caucasians or African-Americans. There were few standard models to study the pathogenic mechanism at molecular level and cell signaling pathway of breast cancer for Asian patients. It is quite necessary to establish new breast cancer cell lines from xanthoderm to study the pathogenic mechanism and therapeutic methods.

RESULTS

Three new breast cancer cell lines, designated BC-019, BC-020 and BC-021, were successfully established and characterized from breast invasive ductal carcinoma tissues of three Chinese female patients. These new cell lines growing as adherent monolayer with characteristic epithelial morphology could be maintained continuously in vitro, and they were ER-, PR- and C-erbB-2-positive. Their chromosomes showed high hyperdiploidy and complex rearrangements, and they displayed aggressive tumorigencity in tumorigenesis test.

CONCLUSION

The three newly established breast cancer cell lines from Chinese patients were tested for a number of, and the results indicate that the cell lines were in good quality and could be served as new cell models in breast cancer study.

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 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.

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 in Caucasians, in contrast to a much earlier onset in Chinese Asians. However, the molecular determinants for this earlier onset are unclear. It has been reported that SNP309 in the promoter of MDM2, the negative regulator of p53, affects the onset age of cancers in females. Essentially, the G allele, rather than the T allele, has been suggested to accelerate the age of cancer onset. Hence, we examined if MDM2 and p53 polymorphisms would be determinants of the early onset phenomenon in Chinese women. Our results indicate that the MDM2 SNP309 G allele is more prevalent in the Chinese population compared with reported frequencies in Caucasians, and increases breast cancer risk of both sporadic cases and those with family history. However, it was the T/T genotype that was associated with earlier onset age of sporadic breast cancers in contrast to the G allele that was associated with the familial cases. Though p53 codon 72 single-nucleotide polymorphism (SNP) did not affect general cancer risk or age of onset, arginine homozygozity, in contrast to proline homozygozity, was found to decrease breast cancer risk in the later onset sporadic cases. Both SNP309 and codon 72 polymorphisms did not affect the stage of cancer. Together, the data suggest that though the MDM2 SNP309 G allele is a risk factor for breast cancer, it does not accelerate, but delays the onset of the sporadic disease in Chinese women, highlighting that differences in ethnicity and family history may influence the role of MDM2 SNP309 in cancer susceptibility.

Influence of MDM2 SNP309 alone or in combination with the TP53 R72P polymorphism in oligodendroglial tumors

The transcription factor p53 and its negative regulator MDM2 are pivotal in normal and cancer cells biology. Recently, a functional single-nucleotide polymorphism in the promoter region of MDM2 (MDM2 SNP309), alone or in combination with TP53 R72P, was shown to be associated with the risk, prognosis, age at onset, molecular markers, and response to chemotherapy of various cancers. This SNP has never been specifically investigated in a large series of oligodendroglial tumors. In a comparison with 232 healthy controls, we retrospectively analyzed blood samples of 293 oligodendroglial tumor patients for MDM2 SNP309. In addition, the TP53 R72P polymorphism and chromosome 1p/19q status, a major biomarker in oligodendroglial tumors, were investigated. The frequencies of T/T, T/G, and G/G genotypes in patients and controls did not suggest an increased risk of oligodendroglial tumor formation correlating with MDM2 SNP309. A borderline association was found between MDM2 SNP309 and overall survival (p=0.05), but in multivariate analysis, MDM2 SNP309 did not provide prognostic information complementary to age, tumor phenotype, grade, and 1p/19q status in oligodendroglial tumors. Finally, MDM2 SNP309, alone or in combination with TP53 R72P, was not associated with oligodendroglial tumors.