P53 codon 72 polymorphism contributes to breast cancer risk: a meta-analysis based on 39 case-control studies

Association Between the TP53 Polymorphisms and Breast Cancer Risk: An Updated Meta-Analysis

Background: The relationship of TP53 codons 72, IVS3 16 bp, and IVS6+62A > G polymorphisms with breast cancer (BC) risk has been analyzed in seventeen published meta-analyses. However, the credibility of statistically significant associations was ignored and many new studies have been reported on these themes.

Objectives: To explore whether TP53 codons 72, IVS3 16 bp, and IVS6+62A > G polymorphisms are associated with BC risk and the clinical phenomena.

Methods: To comprehensively search the data (through October 25, 2021), we provided a clear search strategy and reviewed the references of published meta-analyses. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) were used.

Results: The current meta-analysis had a larger sample size than the previous ones: 99 studies with 43,951 BC and 48,479 controls for TP53 codon 72 polymorphism, 35 studies with 8,705 BC and 7,516 controls for IVS3 16 bp polymorphism, and 25 studies with 12,222 BC and 12,895 controls for IVS6+62A > G polymorphism. Five gene models were used to explore the association between the three polymorphisms and BC risk, and partial positive results were similar to published meta-analyses results. However, a large number of significant results were considered to be unreliable after correcting with Bayesian false-discovery probability (BFDP), except for the association between TP53 IVS3 16 bp polymorphism and BC risk in overall analysis (GG vs. CC: BFDP = 0.738), matched studies (GG vs. CC: BFDP = 0.173; GG vs. CC + CG: BFDP = 0.447), and tumor size below 2 cm (GG vs. CC: BFDP = 0.088; GG + CG vs. CC: BFDP = 0.730; GG vs. CC + CG: BFDP = 0.311). These unreliable results were confirmed again without new solid results emerging in further sensitivity analysis (only studies in compliance with the quality assessment standard).

Conclusion: After considering the quality of the included studies and the reliability of the results, the present meta-analysis suggested that TP53 codons 72, IVS3 16 bp, and IVS6+62A > G polymorphisms were not significantly associated with the BC risk. Those results which prove that these three polymorphisms increase BC risk are more likely to be false-positive results due to various confounding factors.

At a Crossroads to Cancer: How p53-Induced Cell Fate Decisions Secure Genome Integrity

P53 is known as the most critical tumor suppressor and is often referred to as the guardian of our genome. More than 40 years after its discovery, we are still struggling to understand all molecular details on how this transcription factor prevents oncogenesis or how to leverage current knowledge about its function to improve cancer treatment. Multiple cues, including DNA-damage or mitotic errors, can lead to the stabilization and nuclear translocation of p53, initiating the expression of multiple target genes. These transcriptional programs may be cell-type- and stimulus-specific, as is their outcome that ultimately imposes a barrier to cellular transformation. Cell cycle arrest and cell death are two well-studied consequences of p53 activation, but, while being considered critical, they do not fully explain the consequences of p53 loss-of-function phenotypes in cancer. Here, we discuss how mitotic errors alert the p53 network and give an overview of multiple ways that p53 can trigger cell death. We argue that a comparative analysis of different types of p53 responses, elicited by different triggers in a time-resolved manner in well-defined model systems, is critical to understand the cell-type-specific cell fate induced by p53 upon its activation in order to resolve the remaining mystery of its tumor-suppressive function.

Detection of activating mutations in liquid biopsy of Egyptian breast cancer patients using targeted next-generation sequencing: a pilot study

BACKGROUND

Breast cancer (BC) is the 2^nd most prevalent malignancy worldwide and is the most prevalent cancer among Egyptian women. The number of newly described cancer-associated genes has grown exponentially since the emergence of next-generation sequencing (NGS) technology. We aim to identify activating mutations in liquid biopsy of Egyptian breast cancer patients using targeted NGS technology. We also demonstrate the microsatellite instability (MSI) status using BAT25, BAT26, and NR27 markers which are tested on the Bioanalyzer 2100 system.

RESULTS

Twenty-one variants were detected in 15 genes: 7 Substitution-Missense, 12 Substitution-coding silent, and 2 Substitution-intronic. Regarding ClinVar database, out of 21 variants there were 14 benign variants, 3 variants with conflicting interpretations of pathogenicity, 3 variants not reported, and 1 drug response variant. TP53 p.(Pro72Arg) missense mutations were found in 75% of patients. PIK3CA p.(Ile391Met), KDR p.(Gln472His) missense mutations were detected in 25% of patients each. Two patients revealed APC gene missense mutation with p.(Ile1307Lys) and p.(Glu1317Gln) variants. Only one patient showed ATM p.(Phe858Leu) gene mutation and one showed FGFR3 p.(Ala719Thr) variant. Regarding microsatellite instability (MSI) status, 2/8 (25%) patients were MSS, 3/8 (37.5%) patients were MSI-L, and 3/8 (37.5%) patients were MSI-HI.

CONCLUSION

It is essential to use and validate minimally invasive liquid biopsy for activating mutations detection by next-generation sequencing especially in patients with inoperable disease or bone metastasis. This work should be extended with larger patient series with comparison of genetic mutations in liquid-based versus tissue-based biopsy and longer follow up period.

Intronic TP53 Polymorphisms Are Associated with Increased Δ133TP53 Transcript, Immune Infiltration and Cancer Risk

We investigated the influence of selected TP53 SNPs in exon 4 and intron 4 on cancer risk, clinicopathological features and expression of TP53 isoforms. The intron 4 SNPs were significantly over-represented in cohorts of mixed cancers compared to three ethnically matched controls, suggesting they confer increased cancer risk. Further analysis showed that heterozygosity at rs1042522(GC) and either of the two intronic SNPs rs9895829(TC) and rs2909430(AG) confer a 2.34-5.35-fold greater risk of developing cancer. These SNP combinations were found to be associated with shorter patient survival for glioblastoma and prostate cancer. Additionally, these SNPs were associated with tumor-promoting inflammation as evidenced by high levels of infiltrating immune cells and expression of the Δ133TP53 and TP53β transcripts. We propose that these SNP combinations allow increased expression of the Δ133p53 isoforms to promote the recruitment of immune cells that create an immunosuppressive environment leading to cancer progression.

Association of PIN3 16-bp duplication polymorphism of TP53 with breast cancer risk in Mali and a meta-analysis

Background

Breast cancer, the most common tumor in women in Mali and worldwide has been linked to several risk factors, including genetic factors, such as the PIN3 16-bp duplication polymorphism of TP53. The aim of our study was to evaluate the role of the PIN3 16-bp duplication polymorphism in the susceptibility to breast cancer in the Malian population and to perform a meta-analysis to better understand the correlation with data from other populations.

Methods

We analyzed the PIN3 16-bp duplication polymorphism in blood samples of 60 Malian women with breast cancer and 60 healthy Malian women using PCR. In addition, we performed a meta-analysis of case-control study data from international databases, including Pubmed, Harvard University Library, Genetics Medical Literature Database, Genesis Library and Web of Science. Overall, odds ratio (OR) with 95% CI from fixed and random effects models were determined. Inconsistency was used to assess heterogeneity between studies and publication bias was estimated using the funnel plot.

Results

In the studied Malian patients, a significant association of PIN3 16-bp duplication polymorphism with breast cancer risk was observed in dominant (A1A2 + A2A2 vs. A1A1: OR = 2.26, CI 95% = 1.08–4.73; P = 0.02) and additive (A2 vs. A1: OR = 1.87, CI 95% = 1.05–3.33; P = 0.03) models, but not in the recessive model (P = 0.38). In the meta-analysis, nineteen (19) articles were included with a total of 6018 disease cases and 4456 controls. Except for the dominant model (P = 0.15), an increased risk of breast cancer was detected with the recessive (OR = 1.46, 95% CI = 1.15–1.85; P = 0.002) and additive (OR = 1.11, 95% CI = 1.02–1.19; P = 0.01) models.

Conclusion

The case-control study showed that PIN3 16-bp duplication polymorphism of TP53 is a significant risk factor for breast cancer in Malian women. These findings are supported by data from the meta-analysis carried out on different ethnic groups around the world.

Targeted next generation sequencing identifies somatic mutations in a cohort of Egyptian breast cancer patients

Breast cancer (BC) incidence is progressively increasing in Egypt. However, there is insufficient knowledge of the acquired somatic mutations in Egyptian BC patients which limit our understanding of its progression. To the best of our knowledge, this is the first Egyptian cohort to sequence a multiple-gene panel of cancer related genes on BC patients. Four hundred and nine cancer related genes were sequenced in 46 fresh breast tumors of Egyptian BC patients to identify somatic mutations and their frequencies. TP53 and PIK3CA were the most top two frequently mutated genes. We detected 15 different somatic mutations in TP53 and 8 different ones in PIK3CA, each in 27 samples (58.7%). According to Clinvar database; we found 19 pathogenic somatic mutations: 7 in Tp53, 5 in PIK3CA, and single variants of VHL, STK11, AKT1, KRAS, IDH2, PTEN and ERBB2. We also identified 5 variants with uncertain significance (4 in TP53 and 1 in CEBPA) and 4 variants with conflicting interpretations of pathogenicity (2 in TP53 and 1 in each of APC and JAK3). Moreover, one drug response variant (p.P72R) in TP53 was detected in 8 samples. Furthermore, four novel variants were identified in JAK2, MTOR, KIT and EPHB. Further analysis, by Ingenuity Variant Analysis software (IVA), showed that PI3K/AKT signaling is altered in greater than 50% of Egyptian BC patients which implicates PI3K/AKT signaling as a therapeutic target. In this cohort, we shed the light on the most frequently detected somatic mutations and the most altered pathway in Egyptian BC patients.

Dynamic role of the codon 72 p53 single-nucleotide polymorphism in mammary tumorigenesis in a humanized mouse model

Female breast cancer (BrCa) is the most common noncutaneous cancer among women in the United States. Human epidemiological studies reveal that a p53 single-nucleotide polymorphism (SNP) at codon 72, encoding proline (P72) or arginine (R72), is associated with differential risk of several cancers, including BrCa. However, the molecular mechanisms by which these variants affect mammary tumorigenesis remain unresolved. To investigate the effects of this polymorphism on susceptibility to mammary cancer, we used a humanized p53 mouse model, homozygous for either P72 or R72. Our studies revealed that R72 mice had a significantly higher mammary tumor incidence and reduced latency in both DMBA-induced and MMTV-Erbb2/Neu mouse mammary tumor models compared to P72 mice. Analyses showed that susceptible mammary glands from E-R72 (R72 x MMTV-Erbb2/Neu) mice developed a senescence-associated secretory phenotype (SASP) with influx of proinflammatory macrophages, ultimately resulting in chronic, protumorigenic inflammation. Mammary tumors arising in E-R72 mice also had an increased influx of tumor-associated macrophages, contributing to angiogenesis and elevated tumor growth rates. These results demonstrate that the p53 R72 variant increased susceptibility to mammary tumorigenesis through chronic inflammation.

No association of TP53 codon 72 and intron 3 16-bp duplication polymorphisms with breast cancer risk in Chinese Han women: new evidence from a population-based case-control investigation

Background

Many studies have demonstrated that the genetic variants of tumor suppressor gene TP53 contribute to the prediction of breast cancer risk. However, most of them focused on Europeans and Americans; the investigations about Asians, especially Chinese women, are scarce. Thus, the aim of this study was to explore the influence of TP53 codon 72 and intron 3 16-bp duplication polymorphisms on the breast cancer risk in Chinese women, especially those from eastern China.

Methods

Blood samples collected from 254 breast cancer patients and 252 healthy female individuals were investigated. Genotypes of the two polymorphisms were determined by direct sequencing and conventional PCR, respectively.

Results

Heterozygous Arg/Pro and homozygous Del/Del were the most frequent genotypes of the two polymorphisms, respectively. Heterozygous Arg/Pro had a higher prevalence in breast cancer cases (P_adj = 0.10; OR_adj = 1.43, 95% CI 0.93–2.18), and no homozygous 16-bp duplication (Ins/Ins) genotype was found in the whole 506 clinical samples. For the distributions of allele and haplotype frequencies, no statistically significant difference was observed between the two groups when multiple (additive, dominant and recessive) genetic models were utilized in the analysis (P_adj > 0.05).

Conclusion

The results suggested that the two TP53 polymorphisms did not affect breast cancer risk in Chinese Han women, but the heterozygous Arg/Pro may exist as the possible risk genotype of the codon 72 polymorphism in contrast to the homozygous Arg/Arg and Pro/Pro.

Electronic supplementary material

The online version of this article (10.1186/s40001-018-0345-6) contains supplementary material, which is available to authorized users.

Impact of p53 arg72pro SNP on Breast Cancer Risk in North Indian Population

Background:

Genetic changes in p53 gene contribute to breast cancer susceptibility.

Objective and Methods:

A case-control study and a meta-analysis were performed to investigate the role of p53 codon72 SNP with breast cancer susceptibility in Indian women.

Results:

p53 heterozygous arginine variant was associated with decreased risk of breast cancer in total cohort. In meta-analysis, Allelic and GG vs. CC genetic comparison model were found to be associated with breast cancer risk. Moreover, recessive comparison model indicated a protective correlation with breast cancer occurrence.

Conclusion:

The findings of our case-control study and meta-analysis suggest a significant association between p53 Arg72Pro polymorphism and an increased risk of breast cancer in Indian population.

Genetics of breast cancer in African populations: a literature review

Breast cancer (BC) is one of the most complex, diverse and leading cause of death in women worldwide. The present investigation aims to explore genes panel associated with BC in different African regions, and compare them to those studied worldwide.

We extracted relevant information from 43 studies performed in Africa using the following criteria: case-control study, association between genetic variations and BC risk. Data were provided on mutations and polymorphisms associated with BC without fixing a specific date. Case-only studies and clinical trials were excluded.

Our study revealed that the majority of African BC genetic studies remain restricted to the investigation of BRCA1 and BRCA2 genes and differences in their mutations spectrum. Therefore, it is necessary to encourage African researchers to characterize more genes involved in BC using methods generating global information such as next-generation sequencing in order to guide specific and more effective therapeutic strategies for the African community.

The association of polymorphic markers Arg399Gln of XRCC1 gene, Arg72Pro of TP53 gene and T309G of MDM2 gene with breast cancer in Kyrgyz females

Background

The association of genes XRCC1, TP53 and MDM2 with breast cancer (BC) has never been tested in Kyrgyz population. We, therefore, aimed to identify an association of alleles and genotypes of polymorphic markers Arg399Gln of gene XRCC1, Arg72Pro of gene TP53, and T309G of gene MDM2 with the risk of BC in Kyrgyz women.

Methods

This was a case-control study of 219 women of Kyrgyz origin with morphologically verified BC (N = 117) and 102 controls, age-matched with BC cases. The mean age of subjects in this study was 52.2 ± 10.8 years. We extracted DNA from the venous blood and genotyped polymorphic markers Arg399Gln of gene XRCC1, Arg72Pro of gene TP53 and T309G of gene MDM2 using polymerase chain reaction and the method of restriction fragment polymorphism.

Results

Allele 399Gln (OR 1.57; 95% CI 1.05–2.35), Arg399Gln of gene XRCC1 heterozygous genotype (OR 2.77; 95% CI 1.60–4.80), the combination of Arg399Gln/Arg72Pro of genes XRCC1/TP53 heterozygous genotype (OR 3.98; 95% CI 1.57–10.09), Arg399Gln/T309G of genes XRCC1/MDM2 (OR 3.0; 95% CI 1.18–7.56), as well as Arg399Gln/Arg72Pro/T309G of genes XRCC1/TP53/MDM2 (OR 6.40; 95% CI 1.18–34.63) were associated with BC in Kyrgyz women.

Conclusions

This is the first study to identify the inter-loci interaction and to find molecular markers of individual risk of BC in Kyrgyz women.

Association of p53 Codon 72 Polymorphism with Breast Cancer in a Rwandese Population

BACKGROUND AND AIMS

A common polymorphism in the tumor suppressor gene p53 at codon 72 has been suggested to play a role in the development of a number of cancers. This polymorphism has been studied in many populations worldwide, with conflicting results. The present study was planned to assess the association of p53 codon 72 polymorphism with breast cancer development in a Rwandese population.

METHODS

In this study, the polymorphism was examined by allele-specific PCR analysis in 40 patients with breast cancer and 39 healthy controls.

RESULTS

The heterozygous genotype Pro/Arg prevailed in both breast cancer patients and controls, and was present in 80% (32/40) and 92.3% (36/39) of cases, respectively. No statistically significant association was observed between p53 codon 72 polymorphism and breast cancer risk. Distribution of p53 genotypes was also studied according to familial history, tumor grade, and clinical stage, and results clearly showed no statistically significant difference.

CONCLUSION

These results suggest that p53 codon 72 polymorphism could not be assessed as a risk factor marker for predisposition to breast cancer in Rwanda. However, further studies using larger sample sizes are needed to provide more conclusive results and to investigate other genetic mutations affecting the activity of p53.

TP53 codon 72 polymorphism and breast cancer risk in Bangladeshi population

BACKGROUND

Breast cancer, a hereditary or heterogeneous sporadic disease, is the most common cancer in women worldwide. The tumor suppressor TP53 gene has been found to be the most commonly mutated genes in many types of human cancers, including breast cancer. This study aimed to investigate the association of codon 72 polymorphism of TP53 gene with breast cancer risk in Bangladeshi females.

METHODS

The study included 125 cases and 125 healthy controls. Genotyping and polymorphism were determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis.

RESULTS

The frequencies of the three genotypes Arg/Arg, Arg/Pro, and Pro/Pro were 43.2, 33.6, and 23.2% in cases, whereas 48.8, 40.8, and 10.4% in controls, respectively. The frequency of mutant homozygous (Pro/Pro) genotype was significantly increased in breast cancer patients as compared with controls (23.2 vs 10.4%), and showed 2.52-fold significantly increased risk for breast cancer (OR 2.5199, 95% CI 1.19-5.33, p = 0.0157). The frequencies of Pro/Pro genotype were significantly higher in breast cancer cases with non-breast feeding status. Pro allele frequency was found to be significantly increased in breast cancer cases (OR 1.4978, 95% CI 1.0357-2.1662, p = 0.0318).

CONCLUSIONS

Our data suggest that mutant (Pro/Pro) homozygosity at codon 72 of TP53 gene is significantly associated with breast cancer susceptibility in Bangladeshi women. In addition, this association was significantly related to lactating status.

Association of rs1219648 in FGFR2 and rs1042522 in TP53 with premenopausal breast cancer in an Iranian Azeri population

Breast cancer is the most common cancer among women in the world. In Iran, the incidence of breast cancer is on the increase. We here studied the association of rs1219648 in FGFR2 and rs1042522 in TP53 and their interaction in development of early onset sporadic breast cancer in Iranian Azeri population to evaluate epistatic effects on the risk of mammary neoplasia. We genotyped the two polymorphisms in 100 women with early onset breast cancer and 100 healthy women by PCR-RFLP. Allele frequency differences were tested using chi2-test with 95% confident intervals. Our results indicated a statistically significant association (p<0.05) between rs1219648, but not rs1042522, and risk of breast cancer. We also found that the combination of FGFR2 major genotype and TP53 hetero genotype had protective effects against breast cancer , while the hetero allele of FGFR2 in combination with the minor genotype of TP53 was associated with a high risk. This study revealed an important crosstalk between two polymorphisms in FGFR2 and TP53 in development of breast cancer. These candidates risk variants should be further evaluated in studies with a larger sample size.

TP53 polymorphisms in sporadic North Indian breast cancer patients

BACKGROUND

The purpose of this study was to evaluate the potential association of five (p.P47S, p.R72P, PIN3 Ins16bp, p.R213R and r.13494g>a) polymorphisms of TP53 with the risk of developing breast cancer in North Indian Punjabi population.

METHODS

We screened DNA samples of 200 sporadic breast cancer patients (197 females and 3 males) and 200 unrelated healthy, gender and age matched individuals for the polymorphisms.

RESULTS

For the p.P47S polymorphism, we observed the PP genotype in 99.5% of the patients and PS genotype in only 1 patient. All the controls had the wild type PP genotype. The frequency of RR, RP and PP genotype of p.R72P was 23.5% vs 33.5%, 51.5% vs 45.5% and 25% vs 21% in patients and controls respectively. Heterozygous (RP) genotype was increased in breast cancer patients as compared to controls (51.5 vs 45.5%) and showed 1.61 fold significantly increased risk for breast cancer (OR=1.61, 95% CI, 1.01-2.58, p=0.04). In breast cancer patients the frequencies of A1A1, A1A2 and A2A2 genotypes of PIN3 Ins16bp polymorphism were 67%, 26% and 7% respectively whereas in controls the genotype frequencies were 68.5%, 27.5% and 4% respectively, with no significant difference. For p.R213R (c.639A>G), all individuals had homozygous wild type genotype. The frequencies of GG, GA and AA genotypes of TP53 r.13494g>a polymorphism were 62 vs 67.5%, 33 vs 28% and 5 vs 4.5% in patients and controls respectively, again without significant difference. We observed that RP- A1A1 genotype combination of p.R72P and PIN3 Ins16bp and RP-GG combination of p.R72P and r.13494g>a polymorphism showed significant risk of breast cancer (OR=1.65, 95%CI: 0.98-2.78, p=0.05; OR=1.72, 95%CI: 1.01-2.92, p=0.04).

CONCLUSION

The results of present study indicated that among the five TP53 polymorphisms investigated, the p.R72P polymorphism, and the RP-A1A1 and RP-GG genotype combination contribute to breast cancer susceptibility in North Indians.

The effect of Metformin on endometrial tumor-regulatory genes and systemic metabolic parameters in polycystic ovarian syndrome--a proof-of-concept study

The aim of this proof-of-concept study was to determine the effects of three-month Metformin therapy on the expression of tumor-regulatory genes (p53, cyclin D2 and BCL-2) in the endometrium of women with polycystic ovary syndrome (PCOS). A total of 40 women, aged between 21 and 45 years with PCOS (Rotterdam criteria) were recruited. The participants were assessed at pre- and 3-month-post-Metformin therapy for the menstrual regularities, weight reduction, Ferriman Galway scores, fasting blood glucose (FBG), total cholesterol, LDL, HDL and p53, BCL-2 and cyclin D2 gene expression. Five participants conceived spontaneously after the initial recruitment. Majority (68%) resumed regular menstrual cycles after Metformin. There were significant reduction in BMI (p = 0.001), weight (p = 0.001) and Ferriman Galway scores (p = 0.001). A significant improvement was seen in mean FBG (p = 0.002), total cholesterol (p = 0.001), LDL (p = 0.003) and HDL cholesterol levels (p = 0.015). Tumor suppressor gene (p53) was significantly up-regulated after Metformin (10 out of 14 women), with p value 0.016. BCL-2 and cyclin D2 (oncogenes) were slightly up-regulated without significant difference (p = 0.119 and 0.155, respectively). In conclusion, Metformin therapy improved clinical and metabolic parameters in women with PCOS and up-regulated p53 tumor suppressor gene significantly. Further studies are however required to independently validate our findings.

EGF +61A/G polymorphism contributes to increased gastric cancer risk: evidence from a meta-analysis

Background

Epidermal growth factor (EGF) plays a pivotal role in cell proliferation, differentiation, and tumorigenesis of epithelial tissues. Variation of the EGF +61A/G (rs4444903) can lead to an alteration in EGF production and/or activity, which may result in individual susceptibility to gastric cancer. Studies investigating the association between EGF +61A/G polymorphism and gastric cancer risk produced inconsistent results. The aim of this study was to quantitatively summarize the evidence for such an association.

Methods

Eligible studies on the association between EGF +61A/G polymorphism and gastric cancer risk were identified by search of electronic databases including PubMed, EMBASE, Cochrane Library, and Chinese Biomedical Literature database (CBM). Data were extracted by two independent authors and pooled odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the strength of the association. Metaregression and subgroup analyses were performed to identify the source of heterogeneity.

Results

Finally, six case–control studies with 1547 gastric cancer cases and 2762 controls were eventually identified. Overall, significant increased gastric cancer risk was found when all studies were pooled in the meta-analysis (GG vs. AA: OR = 1.438, 95% CI 1.021–2.025, P = 0.038; GG + AG vs. AA: OR = 1.256, 95% CI 1.025–1.539, P = 0.028; GG vs. AG + AA: OR = 1.265, 95% CI 1.002–1.596, P = 0.048). In subgroup analysis by ethnicity, source of control, study quality, and HWE in controls, significant increased gastric cancer risk was observed in Asians, population-based studies, high quality studies, and studies consistent with HWE. In subgroup analysis according to tumor location, and histological type, significant association was observed in all subgroups.

Conclusions

This meta-analysis suggested that the EGF +61A/G polymorphism contributes to increased gastric cancer risk, especially in Asian populations. Further well-designed studies based on large sample size in diverse populations are needed to confirm this association.

Association between XPD Lys751Gln and Asp312Asn polymorphisms and hepatocellular carcinoma risk: a systematic review and meta-analysis

Genetic polymorphisms of xeroderma pigmentosum group D (XPD) in the nucleotide excision repair pathway may influence cancer susceptibility by affecting the capacity for DNA repair. Studies investigating the association between XPD Lys751Gln and Asp312Asn polymorphisms and hepatocellular carcinoma (HCC) risk reported inconsistent results. The aim of this study was to quantitatively summarize the evidence for such an association. Eligible studies were identified by searching electronic databases including PubMed, Embase, Cochrane library, and CBM, Chinese Biomedical Literature Database, for the period up to October 2014. The association of XPD Lys751Gln and Asp312Asn polymorphisms and HCC risk was assessed by odds ratios (ORs) together with their 95% confidence intervals (CIs). Finally, a total of 11 studies with 4322 cases and 4970 controls were included for XPD Lys751Gln polymorphism and 6 studies with 2223 cases and 2441 controls were available for XPD Asp312Asn polymorphism. With respect to XPD Lys751Gln polymorphism, statistically significant increased HCC risk was found when all studies were pooled into the meta-analysis (Gln/Gln vs Lys/Lys: OR = 1.363, 95% CI 1.065-1.744, P = 0.014; Lys/Gln vs Lys/Lys: OR = 1.205, 95% CI 1.099-1.321, P = 0.000; Gln/Gln+Lys/Gln vs Lys/Lys: OR = 1.300, 95% CI 1.141-1.480, P = 0.000). In subgroup analyses by ethnicity, source of control, Hardy-Weinberg equilibrium (HWE) in controls, hepatitis B virus (HBV) infection, and statistically significant increase of HCC risk was found in East Asians, population-based studies, studies consistent with HWE, and HBV-positive subjects, but not in mixed/other populations, hospital-based studies, studies deviating from HWE, and HBV-negative subjects. With respect to XPD Asp312Asn polymorphism, no significant association with HCC risk was found in the overall and subgroup analyses. The results suggest that the XPD Lys751Gln polymorphism contributes to increased HCC susceptibility, especially in East Asian populations. Further, large and well-designed studies are required to validate this association.

The association of common functional polymorphisms in mir-146a and mir-196a2 and hepatocellular carcinoma risk: evidence from a meta-analysis

MicroRNAs (miRNAs) are small non-coding RNA molecules that function as tumor suppressors or oncogenes. Single nucleotide polymorphisms (SNPs) located in the miRNAs influence the function of mature miRNAs and may contribute to cancer development. Studies investigating the association between miR-146a rs2910164 and miR-196a2 rs11614913 polymorphisms and hepatocellular carcinoma (HCC) risk reported inconsistent results. We performed a meta-analysis of all available studies to summarize this situation. Eligible studies were identified by search of electronic databases including PubMed, Embase, and Cochrane library for the period up to August 2014. The association of miR-146a rs2910164 and miR-196a2 rs11614913 polymorphisms and HCC risk was assessed by odds ratios (ORs) together with their 95% confidence intervals (CIs). Finally, a total of 12 studies with 4171 cases and 4901 controls were included for miR-146a rs2910164 polymorphism and 10 studies with 4687 cases and 4990 controls were available for miR-196a2 rs11614913 polymorphism. With respect to miR-146a rs2910164 polymorphism, statistical significant increased HCC risk was found when all studies were pooled into the meta-analysis (GG+CG vs CC: OR = 1.097, 95% CI 1.005-1.197, P = 0.037). In subgroup analyses by ethnicity, source of control, and HWE in controls, significant increase of HCC risk was found in Asians, population-based studies, and studies consistent with HWE, but not in Caucasians, hospital-based studies, and studies inconsistent with HWE. With respect to miR-196a2 rs11614913 polymorphism, no significant association with HCC risk was found in the overall and subgroup analyses. The results suggest that the miR-146a rs2910164 polymorphism contributes to increased HCC susceptibility, especially in Asian populations. Further large and well-designed studies are required to validate this association.

p53 codon 72 polymorphism interactions with dietary and tobacco related habits and risk of stomach cancer in Mizoram, India

BACKGROUND

This study was carried out to investigate the interaction of p53 codon 72 polymorphism, dietary and tobacco habits with reference to risk of stomach cancer in Mizoram, India. A total of 105 histologically confirmed stomach cancer cases and 210 age, sex and ethnicity matched healthy population controls were included in this study.

MATERIALS AND METHODS

The p53 codon 72 polymorphism was detected by PCR-RFLP and sequencing. H. pylori infection status was determined by ELISA. Information on various dietary and tobacco related habits was recorded with a standard questionnaire.

RESULTS

This study revealed that overall, the Pro/ Pro genotype was significantly associated with a higher risk of stomach cancer (OR, 2.54; 95%CI, 1.01-6.40) as compared to the Arg/Arg genotype. In gender stratified analysis, the Pro/Pro genotype showed higher risk (OR, 7.50; 95%CI, 1.20-47.0) than the Arg/Arg genotype among females. Similarly, the Pro/Pro genotype demonstrated higher risk of stomach cancer (OR, 6.30; 95%CI, 1.41-28.2) among older people (>60 years). However, no such associations were observed in males and in individuals <60 years of age. Smoke dried fish and preserved meat (smoke dried/sun dried) consumers were at increased risk of stomach cancer (OR, 4.85; 95%CI, 1.91-12.3 and OR, 4.22; 95%CI, 1.46-12.2 respectively) as compared to non-consumers. Significant gene-environment interactions exist in terms of p53 codon 72 polymorphism and stomach cancer in Mizoram. Tobacco smokers with Pro/Pro and Arg/Pro genotypes were at higher risk of stomach cancer (OR, 16.2; 95%CI, 1.72-153.4 and OR, 9.45; 95%CI, 1.09-81.7 respectively) than the non-smokers Arg/Arg genotype carriers. The combination of tuibur user and Arg/Pro genotype also demonstrated an elevated risk association (OR, 4.76; 95%CI, 1.40-16.21).

CONCLUSIONS

In conclusion, this study revealed that p53 codon 72 polymorphism and dietary and tobacco habit interactions influence stomach cancer development in Mizoram, India.

Genetic variation in the TP53 pathway and bladder cancer risk. a comprehensive analysis

INTRODUCTION

Germline variants in TP63 have been consistently associated with several tumors, including bladder cancer, indicating the importance of TP53 pathway in cancer genetic susceptibility. However, variants in other related genes, including TP53 rs1042522 (Arg72Pro), still present controversial results. We carried out an in depth assessment of associations between common germline variants in the TP53 pathway and bladder cancer risk.

MATERIAL AND METHODS

We investigated 184 tagSNPs from 18 genes in 1,058 cases and 1,138 controls from the Spanish Bladder Cancer/EPICURO Study. Cases were newly-diagnosed bladder cancer patients during 1998-2001. Hospital controls were age-gender, and area matched to cases. SNPs were genotyped in blood DNA using Illumina Golden Gate and TaqMan assays. Cases were subphenotyped according to stage/grade and tumor p53 expression. We applied classical tests to assess individual SNP associations and the Least Absolute Shrinkage and Selection Operator (LASSO)-penalized logistic regression analysis to assess multiple SNPs simultaneously.

RESULTS

Based on classical analyses, SNPs in BAK1 (1), IGF1R (5), P53AIP1 (1), PMAIP1 (2), SERINPB5 (3), TP63 (3), and TP73 (1) showed significant associations at p-value≤0.05. However, no evidence of association, either with overall risk or with specific disease subtypes, was observed after correction for multiple testing (p-value≥0.8). LASSO selected the SNP rs6567355 in SERPINB5 with 83% of reproducibility. This SNP provided an OR = 1.21, 95%CI 1.05-1.38, p-value = 0.006, and a corrected p-value = 0.5 when controlling for over-estimation.

DISCUSSION

We found no strong evidence that common variants in the TP53 pathway are associated with bladder cancer susceptibility. Our study suggests that it is unlikely that TP53 Arg72Pro is implicated in the UCB in white Europeans. SERPINB5 and TP63 variation deserve further exploration in extended studies.

Intron 3 sixteen base pairs duplication polymorphism of p53 contributes to breast cancer susceptibility: evidence from meta-analysis

Background

P53 is a tumor suppressor gene and plays important role in the etiology of breast cancer. Intron 3 sixteen-bp duplication polymorphism of p53 has been reported to be associated with breast cancer risk. However, the reported results remain conflicting rather than conclusive.

Methods

A meta-analysis including 19 case-control studies was performed to address this issue. Odds ratios (ORs) with 95% confidence intervals (CIs) were adopted to evaluate the association.

Results

The overall results suggested that the variant genotypes were associated with a significantly increased breast cancer risk (Del/Ins vs Del/Del: OR = 1.18, 95% CI: 1.00–1.40; Ins/Ins vs Del/Del: OR = 1.42, 95% CI = 1.09–1.84; Ins/Ins+Del/Ins vs Del/Del: OR = 1.21, 95% CI = 1.03–1.41). When stratifying by sample size of studies, a significantly elevated risk was also observed among large sample studies (>500 subjects) but not among small sample studies (≤500 subjects).

Conclusion

These results suggested that the 16-bp duplication polymorphism of p53 may contribute to susceptibility to breast cancer. Additional well-designed large studies were required to validate this association in different populations.

p53 codon 72 polymorphism and breast cancer risk: A meta-analysis

p53 is a tumor suppressor gene and plays important roles in the etiology of breast cancer. Studies have produced conflicting results concerning the role of p53 codon 72 polymorphism (G>C) on the risk of breast cancer; therefore, a meta-analysis was performed to estimate the association between the p53 codon 72 polymorphism and breast cancer. Screening of the PubMed database was conducted to identify relevant studies. Studies containing available genotype frequencies of the p53 codon 72 polymorphism were selected and a pooled odds ratio (OR) with 95% confidence interval (CI) was used to assess the association. Sixty-one published studies, including 28,539 breast cancer patients and 32,788 controls were identified. The results suggest that variant genotypes are not associated with breast cancer risk (Pro/Pro + Arg/Pro vs. Arg/Arg: OR=1.016, 95% CI=0.931–1.11, P=0.722). The symmetric funnel plot, Egger’s test (P=0.506) and Begg’s test (P=0.921) were all suggestive of the lack of publication bias. This meta-analysis suggests that the p53 codon 72 Pro/Pro + Arg/Pro genotypes are not associated with an increased risk of breast cancer. To validate the association between the p53 codon 72 polymorphism and breast cancer, further studies with larger numbers of participants worldwide are required.

Association between p53 codon 72 genetic polymorphisms and tobacco use and lung cancer risk in a Chinese population

Genetic polymorphisms of p53 codon 72 are thought to have significant effects on the metabolism of environmental carcinogens and thus on lung cancer risk, but the reported results are not always consistent. The aim of this study is to investigate the relationship between p53 codon 72 genetic polymorphisms and tobacco use and lung cancer risk in a Chinese population. A population-based control study was conducted in 360 lung cancer patients and 360 cancer-free controls. The genotype of the p53 codon 72 was determined by using a polymerase chain reaction-restriction fragment length polymorphism assay. Patients with lung cancer had a significantly lower frequency of Pro/Pro genotype [odds ratio (OR) = 0.58, 95 % confidence interval (CI) = 0.40, 0.84; P = 0.004] and Pro allele (OR = 0.72, 95 % CI = 0.59, 0.89; P = 0.002) than controls. Patients with squamous cell carcinoma had also a significantly lower frequency of Pro/Pro genotype (OR = 0.45, 95 % CI = 0.25, 0.82; P = 0.009). In the analysis combining p53 codon 72 polymorphisms and smoking, smokers who had smoked for more than 30 pack-years had a significantly lower frequency of Pro/Pro genotype (OR = 0.52, 95 % CI = 0.30, 0.92; P = 0.03) compared with non-smokers. This study suggests that p53 codon 72 polymorphisms play a role in the development of lung cancer and modifies the risk for smoking-related lung cancer in a Chinese population.

The Pro allele of the p53 codon 72 polymorphism is associated with decreased intratumoral expression of BAX and p21, and increased breast cancer risk

Background

The TP53 Arg72Pro polymorphism encodes two p53 variants with different biochemical properties. Here we investigated the impact of this polymorphism on the expression of key p53 target genes in a panel of human breast carcinomas, breast cancer risk, and age at onset.

Methodology/Principal Findings

The Arg72Pro polymorphism was genotyped in 270 breast cancer patients and 221 control subjects. In addition, the Arg72Pro genotype of 116 breast tumors was determined, and correlated with intratumoral mRNA expression of TP53 and its key target genes MDM2, p21, BAX, and PERP, as quantified by qRT-PCR. We found a significantly increased breast cancer risk associated with the Pro-allele (per-allele odds ratio, 1.46; 95% confidence interval, 1.08–1.99), and a significantly later mean age at breast cancer onset for Pro/Pro patients (63.2±18 years) compared to Arg/Arg patients (58.2±15 years). The frequency of somatic TP53 inactivation was 25.4% in Arg/Arg, 20.9% in Arg/Pro, and 16.7% in Pro/Pro patients, which may reflect a higher selective pressure to mutate the Arg-allele. The median mRNA levels of p21 and BAX in the tumors of Pro-allele carriers were significantly reduced to 55.7% and 76.9% compared to Arg/Arg patients, whereas p53, MDM2 and PERP expression were hardly altered.

Conclusions/Significance

The p53^72Arg variant appears to be a more potent in vivo transcription factor and tumor suppressor in human breast cancer than the p53^72Pro variant. The Arg72Pro genotype has no significant effects in patients with TP53 mutated tumors, in which p53 is non-functional.

p53 codon 72 polymorphism and hematological cancer risk: an update meta-analysis

Background

Previous studies on the association of p53 codon 72 (Arg72Pro) polymorphism with hematological malignancies risk have produced conflicting results. The purpose of this meta-analysis is to define the effect of p53 Arg72Pro polymorphism on hematological malignancies risk.

Methodology/Principal Findings

Through searching PubMed databases (or hand searching) up to April 2012 using the following MeSH terms and keywords: “p53”, “codon 72” “polymorphism” and “leukemia”, or “lymphoma”, or “myeloma”, thirteen were identified as eligible articles in this meta-analysis for p53 Arg72Pro polymorphism (2,731 cases and 7, 356 controls), including nine studies on leukemia (1,266 cases and 4, 474 controls), three studies on lymphoma (1,359 cases and 2,652 controls), and one study on myeloma. The overall results suggested that p53 Arg72Pro polymorphism was not associated with hematological malignancies risk. In stratified analyses, significantly increased non-Hodgkin lymphomas risk was found in p53 Arg72Pro polymorphism heterozygote model (Arg/Pro vs. Arg/Arg: OR = 1.18, 95%CI: 1.02–1.35) and dominant model (Arg/Pro+Pro/Pro vs. Arg/Arg: OR = 1.18, 95%CI: 1.03–1.34), but no significant association was found between leukemia risk and p53 Arg72Pro polymorphism. Further studies showed no association between leukemia risk and p53 Arg72Pro polymorphism when stratified in subtypes of leukemias, ethnicities and sources of controls.

Conclusions/Significance

This meta-analysis indicates that the p53 Arg72Pro polymorphism may contribute to susceptibility to non-Hodgkin lymphomas.

Alterations of the TP53 gene in gastric and esophageal carcinogenesis

TP53 genes is one of more important tumor suppressor gene, which acts as a potent transcription factor with fundamental role in the maintenance of genetic stability. The development of esophageal and gastric cancers is a multistep process resulting in successive accumulation of genetic alterations that culminates in the malignant transformation. Thus, this study highlights the participation of the main genetic alterations of the TP53 gene in esophageal and gastric carcinogenesis. Among these changes, high frequency of TP53 mutations, loss of heterozygosity (LOH), overexpression of the p53 protein, and consequently loss of p53 function, which would be early events in esophageal and gastric cancers, as well as an important biomarker of the prognosis and treatment response. Furthermore, Single Nucleotide Polymorphisms (SNPs) of TP53 have been implicated in the development and prognosis of several cancers, mainly TP53 codon 72 polymorphism whose role has been extensively studied in relation to susceptibility for esophageal and gastric cancer development.

Meta-analysis of the association between P53 codon 72 polymorphisms and gastric cancer

PURPOSE

This meta-analysis aims to examine whether the P53 codon 72 polymorphisms is associated with gastric cancer risk.

METHODS

Pooled odds ratios (ORs) were appropriately derived from random-effects models. Separate analyses were conducted on Asian and Caucasian populations. And a total of 21 studies were eligible (5,867 cases and 7,001 controls); 15 of them were conducted on Asians, others on Caucasians.

RESULTS

The combined results based on all studies showed that there was significant difference in genotype distribution between gastric cancer and non-cancer patients in the allele contrast (Pro vs. Arg); the codominant model (Pro/Pro vs. Arg/Arg) and the recessive model (Pro/Pro vs. Pro/Arg + Arg/Arg). When stratifying for race, patients with gastric cancer had a significantly higher frequency of Pro (OR = 1.136, 95% CI = 1.051-1.229), Pro/Pro (OR = 1.314, 95% CI = 1.110-1.555), Pro/Arg (OR = 1.099, 95% CI = 1.009-1.197), (Pro/Pro + Pro/Arg (OR = 1.153, 95% CI = 1.059-1.255) than non-cancer patients among Asians. There was statistically significant heterogeneity across all included studies with the Q statistic and study population may be the most important factor contributed to the heterogeneity.

CONCLUSIONS

In conclusion, the P53 codon 72 polymorphisms seems to be associated with gastric cancer risk and the analyses suggested that P53 codon 72 polymorphisms may be an important biomarker of gastric cancer susceptibility for Asians.

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.

TUMOR SUPPRESSOR PATHWAYS AND CELLULAR ORIGINS OF BREAST CANCER: NEW COMPLEXITIES AND NEW HOPES

Heritable breast cancer syndromes have identified the recognition and processing of DNA double strand breaks as a fundamental vulnerability in the breast epithelium. The role of homology-directed DNA repair is particularly prominent, indicating that this repair pathway is rate-limiting. Although the activities of the tumor suppressor genes underlying heritable breast cancer act in a common pathway of DNA double strand break repair, the specific lesions result in surprisingly different patterns of biomarkers in the breast cancers, suggesting that they arise from different cell types that include the luminal, basal and progenitor cells within the breast epithelium. Therefore, each cell type appears to have distinct underlying vulnerabilities in repair of DNA double strand breaks. While the heterogeneity of targets poses a challenge to develop specific therapies, these pathways also render tumor cells sensitive to drugs targeting double strand break repair pathways offering new options for therapies. As double strand break repair is a common pathway underlying breast cancer risk, therapies that enhance the proficiency of this pathway offer a strategy for chemoprevention.

The p53 codon 72 polymorphism is associated with risk and early onset of breast cancer among Saudi women

Breast cancer has a major impact on the health of women worldwide. In the Kingdom of Saudi Arabia (KSA), breast cancer incidence is on the increase and is characterized by early onset and aggressiveness. Owing to the importance of the TP53 gene in breast carcinogenesis, we analyzed the possible link between TP53 single nucleotide polymorphisms (SNPs) and the risk of breast cancer in Saudi women by direct sequencing of the TP53 gene exon 4 from 100 breast cancer tissues. The proportion of the polymorphic forms of SNP72 in the Saudi breast cancer patients were: Arg/Arg (RR), 39%; Pro/Pro (PP), 36%; and Arg/Pro (RP), 25%. The frequencies of these forms in disease-free Saudi women were 7.59, 22.22 and 60.19%, respectively. This indicates that the RR form of the codon 72 polymorphism is a potential risk factor, whereas the RP form is a protection factor against breast cancer among Saudi women (p=0.0001). Moreover, the results have shown that the p53 R72P SNP is significantly associated with the early onset of breast cancer in the Saudi population (p=0.0138). However, the codon 47 polymorphism appears to have no role in this disease among Saudi women. These results indicate that the TP53 gene could play a major role in breast carcinogenesis and the early onset of the disease among Saudi women.

p53 codon 72 polymorphism and endometriosis: a meta-analysis

BACKGROUND

p53 tumour suppressor gene Arg72Pro polymorphism has been associated with endometriosis. However, the current available data were inconsistent. We performed this meta-analysis to estimate the association between p53 Arg72Pro polymorphism and endometriosis.

METHODS

Electronic screening of PubMed library was conducted to select studies. Studies containing available genotype frequencies of Arg72Pro were chosen, and pooled odds ratio (OR) with 95% confidence interval (CI) was used to assess the association.

RESULTS

Six published studies, including 749 endometriosis and 857 controls were identified. The overall results suggested that the variant genotypes were not associated with the endometriosis risk (Pro/Pro + Arg/Pro vs. Arg/Arg: OR = 1.552, 95% CI 0.916-2.632, p = 0.103). In the stratified analysis, individuals carried the Pro allele in a dominant model had increased risk of endometriosis (OR = 2.595, 95% CI 1.005-6.702, p = 0.049) in Asian subjects. The symmetric funnel plot, the Egger's test (p = 0.602), and the Begg's test (p = 0.167) were all suggestive of the lack of publication bias. However, the association was not significant between this polymorphism and endometriosis in Caucasian (OR = 1.005, 95% CI 0.755-1.337, p = 0.972).

CONCLUSION

This meta-analysis suggests that p53 codon 72 Pro/Pro + Arg/Pro genotypes are associated with increased risk of endometriosis in Asian. To validate the association between p53 codon 72 polymorphism and endometriosis, further studies with larger participants worldwide are needed.

Coordination of TP53 abnormalities in breast cancer: data from analysis of TP53 polymorphisms, loss of heterozygosity, methylation, and mutations

AIMS

We have studied whether TP53 rs1042522, rs17878362, and rs1625895 alleles having a protective effect against breast cancer (BC) will be lost in tumors, whereas those allowing disease development will be retained.

METHODS

Analysis of TP53 polymorphisms was performed in blood leukocytes and tumors from 80 Caucasian BC patients. In addition, TP53 loss of heterozygosity (LOH), methylation, and mutations were studied in tumor DNA of BC individuals with loss of alleles of TP53 polymorphisms.

RESULTS

In breast tumors of patients heterozygous for TP53 polymorphisms, we detected loss of rs1042522 C and G and rs17878362 A2 alleles; however, the loss of the C allele was preferential. We found that loss of TP53 alleles, namely rs1042522 C, has been caused by an LOH mechanism, namely TP53 deletions, whereas TP53 point mutations frequently occurred in the retained G allele (p=0.03). In addition, we showed that BC patients with rs1042522 CC genotype were characterized by only unifocal tumors and decreased frequency of lymph node metastases (p=0.03).

CONCLUSIONS

Taken together, we showed the preferential loss of the rs1042522 C allele, which is protective against BC progression, in breast tumors. Also, the loss of the C allele, which encodes p53 protein with the best DNA repair capability according to literature data, may create prerequisites for mutations, but not for methylation in a retained G variant, as we found here. However, these results need to be confirmed because of the limited statistical power of the present study and the small sampling.

Current evidence on the relationship between four polymorphisms in the matrix metalloproteinases (MMP) gene and breast cancer risk: a meta-analysis

The matrix metalloproteinases (MMP) can degrade various components of the extracellular matrix and its functional genetic polymorphisms may be associated with breast cancer risk. However, this relationship remains controversial. A meta-analysis was conducted in order to investigate the potential association between four polymorphisms in the MMP gene and breast cancer risk. A database search yielded a total of 9 studies involving 2,597 cases and 2,618 controls. Four polymorphisms were included in the meta-analysis: MMP-1 -1607 2G/1G (rs1799750), MMP-2 -1306 C/T (rs243865), MMP-3 -1171 6A/5A (rs3025058) and MMP-9 -1562 C/T (rs3918242). Crude odds ratios (OR) with 95% confidence intervals (CI) were used to assess the strength of association. When all the studies were pooled into the meta-analysis, we found that breast cancer cases had a significantly higher frequency of CC genotype (OR = 1.27, 95% CI = 1.10, 1.47; P = 0.001) and lower frequency of CT genotype (OR = 0.78, 95% CI = 0.67, 0.91; P = 0.001) of MMP-2. No significant difference was found in any genotype of MMP-1, MMP-3 or MMP-9. In conclusion, this meta-analysis suggested that MMP-2 -1306 C/T polymorphism may contribute to breast cancer susceptibility. More studies were needed especially in Asians in the future.

Association between the p53 polymorphisms and breast cancer risk: meta-analysis based on case-control study

p53 is a tumor suppressor gene and plays an important role in the etiology of breast cancer. However, studies on the association between p53 polymorphisms and breast cancer risk have yielded conflicting results. We performed a meta-analysis to investigate the association between breast cancer and the p53 polymorphisms codon 72 (27,046 cases and 30,998 controls), IVS3 16 bp (3,332 cases and 3,700 controls) and IVS6+62A>G (8,787 cases and 9,869 controls) in different inheritance models. When all the eligible studies of codon 72 polymorphism were pooled into this meta-analysis, there was no evidence of significant association between breast cancer risk and p53 codon 72 polymorphism in any genetic model. However, in the stratified analysis for Indian population, significantly association was observed in additive model (OR = 0.62, 95% CI = 0.46-0.82, P value of heterogeneity test [P (h)] = 0.153) and recessive model (OR = 0.70, 95% CI = 0.50-0.92, P (h) = 0.463). IVS3 16 bp was significantly associated with breast cancer risk in a pooled 15 studies dataset (dominant model: OR = 1.14, 95% CI = 1.02-1.27, P (h) = 0.30; recessive model: OR = 1.61, 95% CI = 1.21-2.25, P(h) = 0.25; additive model: OR = 1.66, 95% CI = 1.24-2.21, P (h) = 0.28). No significant association was found between IVS6+62A>G polymorphism and breast cancer risk in a total of 14 studies. In summary, these results indicate that IVS3 16 bp is likely an important genetic marker contributing to susceptibility of breast cancer, and codon 72 homozygous mutants may be associated with decreased breast cancer risk in Indian population.

TP53 Arg72Pro polymorphism is associated with esophageal cancer risk: A meta-analysis

AIM: To investigate the association between TP53 Arg72Pro polymorphism and esophageal cancer (EC) risk using meta-analysis.

METHODS: All eligible studies published before March 1, 2010 were selected by searching PubMed using keywords “p53” or “TP53”, “polymorphism” or “variation”, “esophageal” and “cancer” or “carcinoma”. Crude odds ratios (ORs) with 95% confidence intervals (CIs) were assessed for EC risk associated with TP53 Arg72Pro polymorphism using fixed- and random-effects models.

RESULTS: Nine case-control studies involving 5545 subjects were included in this meta-analysis. Significantly reduced risk of EC was associated with TP53 genotypes for Arg/Arg + Arg/Pro vs Pro/Pro (OR = 0.73, 95% CI: 0.57-0.94, P = 0.014). Subgroup analyses according to the source of controls and the specimens used for determining TP53 Arg72Pro genotypes or sample size showed that significantly reduced risk was observed only in studies which have population-based controls (Arg/Arg vs Pro/Pro: OR = 0.56, 95% CI: 0.47-0.66, P < 0.001), and use white blood cells or normal tissue to assess TP53 genotypes of cases (Arg/Arg vs Pro/Pro: OR = 0.56, 95% CI: 0.47-0.65, P < 0.001) or include at least 200 subjects (Arg/Arg vs Pro/Pro: OR = 0.56, 95% CI: 0.47-0.65, P < 0.001). Analysis restricted to well-designed studies also supported the significantly decreased risk of EC (Arg/Arg vs Pro/Pro: OR = 0.54, 95% CI: 0.46-0.64, P < 0.001).

CONCLUSION: TP53 Arg72 carriers are significantly associated with decreased EC risk. Nevertheless, more well-designed studies are needed to confirm our findings.

Tp53 codon-72 polymorphisms identify different radiation sensitivities to g2-chromosome breakage in human lymphoblast cells

Both the G2 chromosomal radiosensitivity assay and allelic differences in TP53 codon-72 have been associated with cancer predisposition. The relationship between the two endpoints was determined in 56 human EBV-transformed lymphoblastoid cell lines. Although there were overlapping distributions of sensitivity for the different genotypes, cell lines that were homozygous for the proline coding allele were more likely to be resistant to chromatid break formation than those containing two arginine coding alleles, whereas cell lines expressing both the proline and arginine codon were either resistant like proline-proline lines or sensitive like arginine-arginine lines. The results support an important role of the TP53 codon-72 polymorphism in modifying G2-chromosome radiosensitivity. Distinguishing the effect of TP53 codon-72 variations from other modifiers of G2-chromosome radiosensitivity might aid in identifying new markers of cancer risk.

p53 nuclear accumulation and ERalpha expression in ductal hyperplasia of breast in a cohort of 215 Chinese women

Introduction

Women with ductal hyperplasia including usual ductal hyperplasia (UDH) and atypical ductal hyperplasia (ADH) have an increased risk of developing invasive ductal carcinoma (IDC) of breast. The importance of several molecular markers in breast cancer has been of considerable interest during recent years such as p53 and estrogen receptor alpha (ERα). However, p53 nuclear accumulation and ERα expression have not been assessed in ductal hyperplasia co-existing with ductal carcinoma in situ (DCIS) or IDC versus pure ductal hyperplasia without DCIS or IDC.

Materials and methods

We investigated p53 nuclear accumulation and ERα expression in breast ductal hyperplasia in a cohort of 215 Chinese women by immunohistochemistry (IHC), which included 129 cases of pure ductal hyperplasia, 86 cases of ductal hyperplasia co-existing with DCIS (41 cases) or IDC (45 cases).

Results

Nuclear p53 accumulation was identified in 22.8% of ADH (31/136), 41.5% of DCIS (17/41) and 42.2% of IDC (19/45), and no case of UDH (0/79). No difference in nuclear p53 accumulation was observed between pure ADH and ADH co-existing with DCIS (ADH/DCIS) or IDC (ADH/IDC) (P > 0.05). The positive rate of ERα expression was lower in ADH (118/136, 86.8%) than that in UDH (79/79, 100%) (P < 0.001), but higher than that in DCIS (28/41, 68.3%) or IDC (26/45, 57.8%) respectively (P < 0.001). The frequency of ERα expression was lower in ADH/DCIS (23/29, 79.31%) and ADH/IDC (23/30, 76.67%) than that in pure ADH (72/77, 93.51%) respectively (P < 0.05). There was a negative weak correlation between p53 nuclear accumulation and ERα expression as for ADH (coefficient correlation -0.51; P < 0.001).

Conclusions

Different pathological types of ductal hyperplasia of breast are accompanied by diversity in patterns of nuclear p53 accumulation and ERα expression. At least some pure ADH is molecularly distinct from ADH/CIS or ADH/IDC which indicated the two types of ADH are molecularly distinct entities although they have the same morphological appearance.