Association between MDM2-SNP309 and hepatocellular carcinoma in Taiwanese population

Association between MDM2 SNP309, p53 Arg72Pro, and hepatocellular carcinoma risk: A MOOSE-compliant meta-analysis

Epidemiological studies have determined the associations between polymorphisms on the promoter of MDM2 (SNP309) and the codon 72 on exon 4 of p53 (p53 Arg72Pro) and the risk of hepatocellular carcinoma (HCC); however, the results were not always consistent. The aim of the present meta-analysis was to evaluate the overall associations between these 2 variants and HCC risk.The MEDLINE, Web of science, EMBASE, Cochrane Library, and CNKI databases were searched for eligibility studies and the data were synthesized under the fixed- or random-effects model. Heterogeneity among the studies was evaluated with the Cochrane test Q and I statistic.For MDM2 SNP309, the pooled odds ratio (OR) from 15 independent studies with a total of 4038 cases and 5491 controls suggested a significant association for the variant with HCC risk [allele model, G vs T: pooled OR = 1.48, 95% confidence interval (95% CI) = 1.26-1.73; pooled OR = 1.53, 95% CI = 1.26-1.81, for G/T vs T/T; pooled OR = 2.04, 95% CI = 1.54-2.71 for G/G vs T/T]. For p53 Arg72Pro, a total of 21 studies with 7285 cases and 9710 controls suggested that the variant was also associated with HCC risk under common genetic model (allele Pro vs Arg, pooled OR = 1.13, 95% CI = 1.02-1.25; Pro/Pro vs Arg/Arg, pooled OR = 1.32, 95% CI =1.06-1.64). No publication bias was found for all the meta-analysis as suggested by the Begg funnel plot and Egger tests.These results suggested that variants MDM2 SNP309 and p53 Arg72Pro are susceptibility factors for HCC; however, more studies are warranted to validate the results.

ASSOCIATION BETWEEN MURINE DOUBLE MINUTE 2 - T309G polymorphism and recurrence of hepatocellular carcinoma after surgical treatment

BACKGROUND

Discovery and incorporation of biomarker panels to cancer studies enabled the understanding of genetic variation and its interference in carcinogenesis at molecular level. The potential association between single nucleotide polymorphism (SNP) 309 and increased development of tumors, such as hepatocellular carcinoma, has been subject to several studies. This is the first study on this association conducted in Brazil.

METHODS

62 cases of cirrhotic patients with hepatocellular carcinoma surgically treated by partial hepatectomy (HPT) or by liver transplantation (LTX) from 2000 to 2009 at Santa Casa Hospital Complex, in the city of Porto Alegre, were retrospectively analyzed. Tumor samples from surgical specimen were collected and prepared for study in paraffin blocks.

RESULTS

Overall survival was 26.7 months in the HPT group and 62.4 months in the LTX group (P <0.01). Overall tumor recurrence was 66.7% in the HPT group (10/15) and 17% in the LTX group (8/47) (X²=13.602, P <0.01). Alpha-fetoprotein levels >200ng/mL, microvascular invasion and histological grade were associated with tumor recurrence (P <0.01). Recurrence rates in each surgical group and analysis of factors associated with tumor recurrence, when stratified for each genotypic pattern, were both not statistically significant.

CONCLUSION

G/G genotype was not associated with tumor recurrence after surgical treatment and it did not show any correlation with other prognostic factors.

Interaction between p53 codon 72 and MDM2 309T>G polymorphisms and the risk of hepatocellular carcinoma

The p53 tumor suppressor and its negative regulator, murine double minute 2 (MDM2), play critical roles in carcinogenesis. P53 codon 72 and MDM2 309T>G polymorphisms could influence p53 and MDM2 function, respectively, and might affect cancer susceptibility. We therefore investigated the association between these two SNPs, alone or in combination, and the risk of hepatocellular carcinoma (HCC) in Chinese. In this case-control study, we genotyped p53 codon 72 and MDM2 309T>G polymorphisms in 985 HCC cases and 992 cancer-free age- and sex-matched controls and evaluated their associations with the risk of HCC. Although no significant main effects were found for these two SNPs in the single-locus analysis and stratified analysis by age, sex, smoking, drinking, and hepatitis B virus (HBV) infection, we found that individuals carrying at least one G allele of the MDM2 309T>G polymorphism had statistically significant increased risk of HCC among those with the p53 Pro/Pro genotype (adjusted odds ratio (OR) = 2.23, 95 % confidence interval (95%CI) = 1.20-4.14 for TG genotype; adjusted OR = 2.67, 95%CI = 1.32-5.42 for GG genotype), and the interaction between p53 codon 72 and MDM2 309T>G was significant (P interaction = 0.017). Our findings suggest that the interaction of p53 codon 72 and MDM2 309T>G may play an important role in the etiology of HCC. More studies with well-designed and large sample sizes are required to validate these observations.

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

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

Association between murine double minute 2 T309G polymorphism and risk of liver cancer

During the past decade, a number of studies were published to evaluate the association between murine double minute 2 (MDM2) T309G polymorphism and risk of liver cancer. However, the association between MDM2 T309G polymorphism and risk of liver cancer was still unclear owing to the conflicting results from those published studies. An undated meta-analysis of all eligible studies was carried out to comprehensively assess the association. The pooled odds ratio (OR) with 95 % confidence interval (95% CI) was used to evaluate the association between MDM2 T309G polymorphism and risk of liver cancer. Finally, ten studies with a total of 2,243 cases and 3,471 controls were finally included into the meta-analysis. Overall, there was an association between MDM2 T309G polymorphism and risk of liver cancer (G vs. T: OR=1.39, 95% CI 1.17-1.64, P<0.001; GG vs. TT: OR=1.87, 95% CI 1.34-2.62, P<0.001; GG/GT vs. TT: OR=1.61, 95 % CI 1.24-2.08, P<0.001). Subgroup analysis in Europeans showed that there was also an association between MDM2 T309G polymorphism and risk of liver cancer in Europeans (G vs. T: OR=1.81, 95% CI 1.45-2.27, P<0.001; GG vs. TT: OR=3.26, 95% CI 1.99-5.32, P<0.001; GG/GT vs. TT: OR=2.20, 95% CI 1.58-3.07, P<0.001). Subgroup analysis in Asians showed that there was also an association between MDM2 T309G polymorphism and risk of liver cancer in Asians (G vs. T: OR=1.27, 95% CI 1.06-1.52, P=0.010; GG vs. TT: OR=1.59, 95% CI 1.11-2.27, P=0.011; GG/GT vs. TT: OR=1.41, 95% CI 1.07-1.87, P=0.016). The meta-analysis provides a strong evidence for the association between MDM2 T309G polymorphism and risk of liver cancer.

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

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

TP53 and MDM2 gene polymorphisms, gene-gene interaction, and hepatocellular carcinoma risk: evidence from an updated meta-analysis

Background

The association between TP53 R72P and/or MDM2 SNP309 polymorphisms and hepatocellular carcinoma (HCC) risk has been widely reported, but results were inconsistent. To clarify the effects of these polymorphisms on HCC risk, an updated meta-analysis of all available studies was conducted.

Methods

Eligible articles were identified by search of databases including PubMed, Cochrane Library, EMBASE and Chinese Biomedical Literature database (CBM) for the period up to July 2013. Data were extracted by two independent authors and pooled odds ratio (OR) with 95% confidence interval (CI) was calculated. Metaregression and subgroup analyses were performed to identify the source of heterogeneity.

Results

Finally, a total of 10 studies including 2,243 cases and 3,615 controls were available for MDM2 SNP309 polymorphism and 14 studies containing 4,855 cases and 6,630 controls were included for TP53 R72P polymorphism. With respect to MDM2 SNP309 polymorphism, significantly increased HCC risk was found in the overall population. In subgroup analysis by ethnicity and hepatitis virus infection status, significantly increased HCC risk was found in Asians, Caucasians, Africans, and HCV positive patients. With respect to TP53 R72P polymorphism, no significant association with HCC risk was observed in the overall and subgroup analyses. In the MDM2 SNP309–TP53 R72P interaction analysis, we found that subjects with MDM2 309TT and TP53 Pro/Pro genotype, MDM2 309 TG and TP53 Arg/Pro genotype, and MDM2 309 GG and TP53 Pro/Pro genotype were associated with significantly increased risk of developing HCC as compared with the reference MDM2 309TT and TP53 Arg/Arg genotype.

Conclusions

We concluded that MDM2 SNP309 polymorphism may play an important role in the carcinogenesis of HCC. In addition, our findings further suggest that the combination of MDM2 SNP 309 and TP53 Arg72Pro genotypes confers higher risk to develop HCC. Further large and well-designed studies are needed to confirm this association.

Murine double minute 2 rs2279744 polymorphism and hepatocellular carcinoma risk in East Asians: a meta-analysis

Murine double minute 2 (MDM2) is a crucial negative regulator of p53 function through several mechanisms. There are many studies performed to assess the association between MDM2 rs2279744 polymorphism and hepatocellular carcinoma risk, but the impact of MDM2 rs2279744 polymorphism on hepatocellular carcinoma in East Asians is unclear owing to the inconsistent findings from previous studies. We conducted a comprehensive meta-analysis of epidemiological studies to shed some light on these contradicting results. We used pooled odds ratio (OR) with its 95 % confidence intervals (95 % CI) to assess the association. Overall, seven studies with a total of 4,993 subjects were finally included. The meta-analysis suggested that MDM2 rs2279744 polymorphism was significantly associated with increased risk of hepatocellular carcinoma in East Asians (G versus T: OR = 1.27, 95 % CI 1.06-1.52, P = 0.01; GG versus TT: OR = 1.59, 95 % CI 1.11-2.27, P = 0.01; GG/GT versus TT: OR = 1.41, 95 % CI 1.07-1.87, P = 0.02; GG versus TT/GT: OR = 1.32, 95 % CI 1.08-1.62, P = 0.008). Sensitivity analysis by excluding low-quality study still suggested that the association above was still significant. Thus, the findings from the meta-analysis support that MDM2 rs2279744 polymorphism is significantly associated with increased risk of hepatocellular carcinoma in East Asians.

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/G polymorphism 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 liver cancer in humans and estimated summary odds ratio (OR) with 95% confidence intervals (95% CI) to assess the possible association in a meta-analysis.

RESULTS

The main analysis revealed no significant heterogeneity, and the pooled ORs of fixed-effects were all significant (for G versus T, OR = 1.59, 95% CI 1.42-1.78; for GG versus TT, 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 associations to remain significant.

CONCLUSION

The present meta-analysis of available data showed a significant association between the MDM2 SNP309 T/G polymorphism and liver cancer risk, the MDM2 SNP309 G allele contributing to increased risk in both Asians and Caucasians in a graded, dose-dependent fashion.

Combined effects of p53 and MDM2 polymorphisms on susceptibility and surgical prognosis in hepatitis B virus-related hepatocellular carcinoma

The p53 signaling pathway works as a potent barrier to tumor progression. Two single nucleotide polymorphisms (SNPs) in the gene loci of p53 pathway, p53 codon 72 Arg72Pro and MDM2 SNP309 (T > G), have been shown to cause perturbation of p53 function, but the effect of the two SNPs on the risk of hepatocellular carcinoma (HCC) remains inconsistent. This study investigated the influence of combined p53 Arg72Pro and MDM2 SNP309 on the risk of developing HCC in patients with chronic hepatitis B virus infection, and evaluated the significance of the two combined SNPs on patient prognosis. In total, 350 HCC patients, 230 non-HCC patients, and 96 healthy controls were genotyped for the p53 Arg72Pro and MDM2 SNP309. The combined p53 Pro/Pro and MDM2 G/G genotype was significantly associated with HCC risk (P = 0.047). Multivariate analysis indicated that combined p53 Pro/Pro and MDM2 G/G genotype was an independent factor affecting recurrence and survival (P < 0.05). Patients with combined p53 Pro/Pro and MDM2 G/G genotypes had a poorer prognosis than other genotypes, P < 0.01 for both disease-free survival (DFS) and overall survival (OS). DFS and OS rates also differed significantly between Barcelona Clinic Liver Cancer (BCLC) stage A patients with combined p53 Pro/Pro and MDM2 G/G and other genotypes (P < 0.05). Thus, the combined p53 Pro/Pro and MDM2 G/G genotype is associated with increased risk of developing HCC and is an independent adverse prognostic indicator in early stage HCC.

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.

TP53 and MDM2 gene polymorphisms and risk of hepatocellular carcinoma among Italian patients

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 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.

Evaluation of the association studies of single nucleotide polymorphisms and hepatocellular carcinoma: a systematic review

PURPOSE

For decades of years, hundreds of candidate gene-based association studies explored the relationship between single nucleotide polymorphisms (SNPs) and hepatocellular carcinoma (HCC). There was no systematic review summarized the results of these association studies of candidate SNPs and HCC to date. In order to summarize the results of the association studies, we conducted a concise systematic review.

METHODS

By searching Pubmed database before October 2010, we reviewed all the association studies about candidate SNPs and HCC. If the eligible study number on a given SNP was more than three, we conducted a meta-analysis. We reported here only the overall positive-association results with statistical significance and evaluated the reliability of the associations by using false-positive report probability (FPRP) analysis and the Venice guidelines on genetic epidemiology studies.

RESULTS

Six SNPs of five genes (rs1800562 of HFE, rs17868323 and rs11692021 of UGT1A7, rs2279744 of MDM2, rs1143627 of IL-1B, and rs4880 of MnSOD) showed overall significant associations with HCC. The eligible number of the studies varied from three to nine. Two SNPs (rs1800562 of HFE and rs2279744 of MDM2) passed the FPRP threshold (FPRP < 0.20). According to the Venice guidelines, the associations between the two SNPs (rs1800562 and rs2279744) and HCC were of moderate evidence.

CONCLUSIONS

Two SNPs (rs1800562 of HFE and rs2279744 of MDM2) were associated with HCC with moderate epidemiological evidence and deserve further study and additional biological and clinical assessment.

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.

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.

Role of SUMO-1, MDM2 and P53 in 5-flurouracil-induced apoptosis of HepG2 cells

AIM: To investigate the role of small ubiquitin-like modifier-1 (SUMO-1), murine double minute gene 2 (MDM2) and P53 in 5-flurouracil (5-Fu)-induced apoptosis of HepG2 cells.

METHODS: Non-transfected HepG2 cells and HepG2 cells transfected with pMDM2 and pSUMO-1 plasmids, alone or both, were treated with different concentrations of 5-Fu for 36 hours. The expression of endogenous P53 protein in HepG2 cells was detected by Western blot.

RESULTS: Treatment with 5-Fu significantly increased the relative expression level of endogenous P53 protein and the apoptosis rate of HepG2 cells in a concentration-dependent manner (90.15% ± 4.22% vs 11.27% ± 1.18%, 33.61% ± 3.15% vs 3.22% ± 0.60%, both P < 0.05). Cells transfected with the pMDM2 plasmid had an apparent resistance to 5-Fu-induced apoptosis of HepG2 cells. The relative expression level of P53 protein and the apoptosis rate in cells transfected with the pMDM2 plasmid were much lower than those in non-transfected cells treated with the same concentration of 5-Fu (51.80% ± 0.78% vs 90.15% ± 4.22%; 20.45% ± 2.23% vs 33.61% ± 3.15%, both P < 0.05). No significant differences were noted in the relative expression level of P53 protein and the apoptosis rate between cells co-transfected with the pSUMO-1 and pMDM2 plasmids and non-transfected cells (78.85% ± 2.43% vs 51.80% ± 0.78%, 29.83% ± 0.53% vs 20.45% ± 2.23%, both P < 0.05).

CONCLUSION: SUMO-1 could inhibit MDM2-induced degradation of P53 protein and enhance the nuclear expression of P53, thus promoting 5-Fu-induced cell apoptosis and elevating chemosensitivity.

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.