Pro variant of TP53 Arg72Pro contributes to esophageal squamous cell carcinoma risk: evidence from a meta-analysis

MDM2 and its functional polymorphism SNP309 contribute to the development of esophageal carcinoma

BACKGROUND

Overexpression of the murine double minute 2 (MDM2) has been explored in many tumors with high proliferation and anti-apoptosis ability. However, the role of MDM2 and its functional single nucleotide polymorphism (SNP) rs2279744 (also known as SNP309) in esophageal squamous cell carcinoma (ESCC) remains unclear.

METHODS

We performed a genotype study of blood samples in 360 ESCC patients and 360 healthy control individuals to determine the risk of various rs2279744 in ESCC. To further evaluate the role of rs2279744 in regulating MDM2 expression, we performed an allele-specific reporter assay and investigated whether the SNP-containing sequences functioned as an active enhancer. To examine the functional role of MDM2 on esophageal cancer cell lines, we carried out an MTS assay and flow cytometry analysis.

RESULTS

From the genotyping study, we found that GG genotype of SNP309 significantly increased the risk of ESCC in an additive model [odds ratio (OR) = 2.55, 95% confidence interval (CI) = 1.66-3.89, p = 1.50 × 10-5 ) and in a recessive model (OR = 2.44, 95% CI = 1.69-3.51, p = 1.60 × 10-8 ). Furthermore, the G allele was significantly associated with a higher risk of ESCC (OR = 1.56, 95% CI = 1.26-1.92, p = 2.81 × 10-5 ). In multivariate logistic regression analysis, the GG genotype had increased the occurrence of ESCC by 2.39-fold (95% CI = 1.48-3.8). Compared to the T allele, the variant G allele had significantly higher luciferase activity on the promoter of MDM2 in both cell lines. By transfecting the gene to ESCC lines, we showed that overexpression of MDM2 significantly promote cell proliferation and anti-apoptosis.

CONCLUSIONS

The MDM2 promoter SNP309 is a risk factor for esophageal cancer. MDM2 promotes the proliferation and anti-apoptosis of ESCC.

Meta-analysis of association between rs1447295 polymorphism and prostate cancer susceptibility

Aims

A number of studies have found that the single nucleotide polymorphisms (SNPs) within the 8q24 region of genome were associated with the susceptibility of prostate cancer. Association between 8q24 SNP variant rs1447295 and higher risk of prostate cancer had been investigated, but those studies were incomplete and the conclusions were obscure.

Methods

To better elucidate the relationship between rs1447295 polymorphism and the susceptibility of prostate cancer, we performed a more comprehensive meta-analysis about the association between rs1447295 polymorphism and prostate cancer susceptibility by collecting relevant articles published up to November, 2016 and excluding many replicated cohort data existing in previous reports, which made the conclusion more reliant and objective.

Results

The results showed that there was a significant prostate cancer risk associated with rs1447295 polymorphism not only in the total groups, but also in American, European and Asian descent subgroups. Meanwhile, a comprehensive analysis about the association between rs1447295 polymorphism and prostate cancer risk were conducted by using different clinical characteristic stratifications including Gleason score, tumor stage and PSA level. The result showed that rs1447295 polymorphism was correlated with different stages of prostate cancer

Conclusions

There are strong association between rs1447295 polymorphism and prostate cancer susceptibility in different ethnic groups and different prostate cancer stage, suggesting that rs1447295 might serve as a reliable biomarker for prostate cancer diagnosis.

Association between positive murine double minute 2 expression and clinicopathological characteristics of esophageal squamous cell carcinoma: a meta-analysis

The correlations of murine double minute 2 (MDM2) T309G and esophageal cancer were elucidated because the association between MDM2 expression states and clinicopathological parameters of esophageal squamous cell carcinoma (ESCC) is controversial. We conducted a meta-analysis on studies screened from PubMed, Web of Science, Embase, the Cochrane Library, and the Chinese Biomedical Literature Databases that were published before October 2014. All studies describing the association between MDM2 and ESCC were traced. Meta-analysis was performed using the STATA software (Stata Corp., College Station, TX, USA). A total of 9 studies with 707 cases and 324 controls were included. MDM2 expression was higher in ESCC than in normal esophageal epithelium (odds ratio [OR] 10.38, 95% confidence interval [CI] 6.42-16.78, P < 0.001). High MDM2 expression was associated with early primary tumor stage (T1/T2 vs. T3/T4, OR 0.59, 95% CI 0.38-0.92, P = 0.018) and increased risk of regional lymph node metastasis (N0 vs. N1, OR 1.66, 95% CI 1.03-2.67, P = 0.039). However, no relationship was observed between MDM2 expression and the risk of distant metastasis (OR = 2.09, 95% CI 1.00-4.36, P = 0.050), and MDM2 was not significantly correlated with TP53 expression (OR 1.22, 95% CI 0.53-2.77, P = 0.643). Our analysis suggests that MDM2 acts as a potent marker of early primary tumor stage but higher risk of regional lymph node metastasis in ESCC. However, because of the limited number of studies included, the result should be further clarified by well-designed prospective studies.

Esophageal squamous cell carcinoma (ESCC): advance in genomics and molecular genetics

Esophageal cancer is aggressive and has poor prognosis. Esophageal squamous cell carcinoma (ESCC) is histologically the most prevalent type of esophageal cancer and ranked as the sixth leading cause of cancer death worldwide. In recent years, cancer has been widely regarded as genetic disease, as well as epigenetic abnormalities including DNA methylation, histone deacetylation, chromatin remodeling, gene imprinting and noncoding RNA regulation. In this review, we will provide a general overview of genes, proteins and microRNAs that are involved in the development of ESCC, which aims to enhance our understanding of molecular mechanisms implicated in ESCC development and progression.

Role of the functional variant (-652T>G) in the XRCC4 promoter in prostate cancer

Several genes encoding DNA repair molecules have been proposed as cancer-susceptibility genes. Many studies have suggested that SNPs in XRCC4 could be implicated in altering the risk of prostate cancer (PCa). We examined the role of the functional variant (-652T>G) in the XRCC4 promoter in PCa. The transcriptional activity of XRCC4 gene was measured by luciferase assay. We performed real-time PCR/immunohistochemical assay to verify the association between expression level of XRCC4 mRNA/protein and XRCC4 -652T>G polymorphism. In addition, electrophoretic mobility shift assay (EMSA) was used to confirm whether this polymorphism has an effect on binding ability of the transcription factor. We found that the G variant significantly increased the transcription activity of the XRCC4 gene and the binding ability of transcriptional factor GATA-1 to the XRCC4 promoter. Furthermore, the results suggested that the XRCC4 protein and mRNA were overexpressed in individuals who carried the -652G allele compared to carriers of the -652T allele. In addition, the expression of XRCC4 in PCa tissues was lower than in adjacent normal tissues. Our data suggest that the XRCC4 promoter -652G>T polymorphism is functional and may influence genetic susceptibility to prostate cancer. Case-control studies are required to validate our findings in the future.

A genetic polymorphism in lincRNA-uc003opf.1 is associated with susceptibility to esophageal squamous cell carcinoma in Chinese populations

The development of esophageal squamous cell carcinoma (ESCC) is a multifactorial process, and associations between genetic variants and ESCC have been identified in genome-wide association studies. The aim of this study was to evaluate the effects of single nucleotide polymorphisms (SNPs) of long intergenic non-coding RNAs (lincRNAs) on ESCC susceptibility in Chinese populations. We scoured exons of lincRNAs located in ESCC susceptibility loci for all probable functional SNPs. These 52 SNPs were opted for and genotyped in 1493 ESCC patients and 1553 cancer-free controls from eastern and southern Chinese populations, and their associations with the risk for ESCC were estimated using logistic regression. Functional relevance was further examined by biochemical assays. Significant differences were found between patients and controls in the genotype frequencies for the rs11752942A>G site in the lincRNA-uc003opf.1 exon. Compared with the rs11752942AA genotype, AG and GG genotypes had a significantly reduced risk of ESCC (adjusted odds ratio = 0.73; 95% confidence interval = 0.63-0.84). Biochemical analysis demonstrated that, when compared with the A allele, the rs11752942G allele could markedly attenuate the level of lincRNA-uc003opf.1 both in vivo and in vitro by binding micro-RNA-149*, thereby affecting cell proliferation and tumor growth. These findings indicated that functional polymorphism rs11752942A>G in lincRNA-uc003opf.1 exon might be a genetic modifier for the development of ESCC.

Comparative study and meta-analysis of meta-analysis studies for the correlation of genomic markers with early cancer detection

A large number of common disorders, including cancer, have complex genetic traits, with multiple genetic and environmental components contributing to susceptibility. A literature search revealed that even among several meta-analyses, there were ambiguous results and conclusions. In the current study, we conducted a thorough meta-analysis gathering the published meta-analysis studies previously reported to correlate any random effect or predictive value of genome variations in certain genes for various types of cancer. The overall analysis was initially aimed to result in associations (1) among genes which when mutated lead to different types of cancer (e.g. common metabolic pathways) and (2) between groups of genes and types of cancer. We have meta-analysed 150 meta-analysis articles which included 4,474 studies, 2,452,510 cases and 3,091,626 controls (5,544,136 individuals in total) including various racial groups and other population groups (native Americans, Latinos, Aborigines, etc.). Our results were not only consistent with previously published literature but also depicted novel correlations of genes with new cancer types. Our analysis revealed a total of 17 gene-disease pairs that are affected and generated gene/disease clusters, many of which proved to be independent of the criteria used, which suggests that these clusters are biologically meaningful.

Association between p53 Pro72Arg polymorphism and prostate cancer risk: a meta-analysis

The tumor suppressor gene p53 appears to be important in the development of many human cancers, such as prostate cancer. The association of p53 codon72 polymorphism with prostate cancer has been widely reported; however, the results are inconsistent. To derive a more precise estimation of this relationship, we performed an updated meta-analysis from 10 case-control studies. We conducted a search in the PubMed database without a language limitation, covering all papers published until July 2010. Risk ratios (RR) with 95% confidence intervals(CIs) were used to assess the strength of the association. Ten studies including 1,196 cases and 1,704 controls were selected. Overall, no significant differences of total prostate cancer risk and p53 codon polymorphism was found (Pro/Pro vs Arg/Arg, RR = 1.12, 95%CI=0.74-1.70, P_{heterogeneity} = 0.016, I² = 55.8%; Pro/Pro+Pro/Arg vs Arg/Arg, RR = 1.05, 95%CI=1.00-1.11, P_{heterogeneity} = 0.077, I² = 51.1%). In the stratified analysis by ethnicity, the same results were found. However, in the control subgroup, there was a modest decreased association between prostate cancer risk and population-based control subjects under the recessive genetic model (RR = 0.31, 95%CI=0.10-0.91, P_{heterogeneity} = 0.110, I² =60.8%). This meta-analysis suggested that p53 codon Pro72Arg polymorphism could be weakly associated with prostate cancer risk.

Modeling gene-environment interactions in oral cavity and esophageal cancers demonstrates a role for the p53 R72P polymorphism in modulating susceptibility

A large number of epidemiological studies have linked a common single-nucleotide polymorphism (SNP) in the human p53 gene to risk for developing a variety of cancers. This SNP encodes either an arginine or proline at position 72 (R72P) of the p53 protein, which can alter the apoptotic activity of p53 via transcriptional and non-transcriptional mechanisms. This SNP has also been reported to modulate the development of human papilloma virus (HPV)-driven cancers through differential targeting of the p53 variant proteins by the E6 viral oncoprotein. Mouse models for the p53 R72P polymorphism have recently been developed but a role for this SNP in modifying cancer risk in response to viral and chemical carcinogens has yet to be established experimentally. Here, we demonstrate that the p53 R72P polymorphism modulates the hyperprolferative, apoptotic and inflammatory phenotypes caused by expression of the HPV16 E6 and E7 oncoproteins. Moreover, the R72P SNP also modifies the carcinogenic response to the chemical carcinogen 4NQO, in the presence and absence of the HPV16 transgene. Our findings confirm several human epidemiological studies associating the codon 72 proline variant with increased risk for certain cancers but also suggest that there are tissue-specific differences in how the R72P polymorphism influences the response to environmental carcinogens.

Associations between P53 Arg72Pro and development of digestive tract cancers: a meta-analysis

BACKGROUND AND AIMS

The relationships between P53 Arg72Pro and risks of digestive tract cancers have been extensively studied, and conclusive results were unavailable.

METHODS

Fifty three case-control studies were included through searching the databases of Medline, Embase and CNKI (up to August 2010). The odds ratio (OR) and 95% confidence interval (95% CI) were used to investigate the strength of the associations.

RESULTS

The results showed that there were no overall associations between P53 Arg72Pro and risks of digestive tract cancers. Subgroup analyses showed that P53 Arg72Pro was associated with risk of gallbladder and pancreatic cancer (OR [95% CI]: 1.44 [1.13-1.83] for Pro carriers vs. ArgArg). In addition, subgroup analyses also suggested that the Pro allele was associated with increased risks of digestive tract cancers among Asians (1.19 [1.01-1.42] for ProPro vs. ArgArg). Meanwhile, Pro allele was also suggested to be associated with increased risk of gastric cancer (1.33 [1.02-1.74] for ProPro vs. ArgPro for diffuse type of gastric cancer and 1.29 [1.05-1.57] for ProPro vs. Arg carriers for gastric cardia cancer) and colorectal cancer (1.26 [1.05-1.51] for ProPro vs. ArgPro for population-based case-control studies; 1.43 [1.09-1.87] for ProPro vs. ArgArg for colon cancer; 1.49 [1.09-2.06] for ProPro vs. ArgArg for rectal cancer and 2.22 [1.44-3.44] for ProPro vs. ArgArg for early stage of colorectal cancer).

CONCLUSIONS

This meta-analysis suggests that Pro allele in P53 Arg72Pro is significantly associated with the increased risks of digestive tract cancers, especially for Asians, and for gastric cancer, colorectal cancer and gallbladder and pancreatic cancer.