p 53 codon 72 polymorphism in stomach and colorectal adenocarcinomas in Iranian patients

Epidemiologic Study of Gastric Cancer in Iran: A Systematic Review

BACKGROUND

Gastric cancer (GC) is one of the most common cancers in Iran. Knowledge of the epidemiology of the disease is essential in planning for prevention. So this study aimed to investigate the epidemiological aspects of gastric cancer including prevalence, incidence, mortality, and risk factors of Iran.

METHODS

This systematic review study was based on articles published in both English and Persian languages during the years of 1970-2020 in international databases (PubMed, Web of Science, Scopus) and national databases (including SID, Magiran, and IranDoc). Papers related to epidemiological aspects of the disease including mortality, prevalence, incidence, and risk entered the final review.

RESULTS

According to the studies, the minimum and maximum prevalence of gastric cancer in northwestern Iran (Ardabil) is between 0.2 and 100 per 100,000. Also, the death rate per 100,000 people ranged from 10.6 to 15.72 and the ASMR ranged from 4.2 to 32.2%. On the other hand, the incidence of GC was higher in men than in women (74.9 vs 4.6%). The GC risk ratio was 8-times higher in the elderly than in the other age groups (HR=8.0, 2.7-23.5). The incidence of gastric cancer in patients with H. pylori infection was 18-times and that of smokers 2-times higher than other populations. Low level of economic situation and food insecurity increased the odds of GC by 2.42- and 2.57-times, respectively. It should be noted that there was a direct relationship between consumption of processed red meat, dairy products, fruit juice, smoked and salty fish and legumes, strong and hot tea, and consumption of salt and gastric cancer incidence. There was also an inverse relationship between citrus consumption, fresh fruit, garlic, and gastric cancer. In addition, the mRNA genes are the most GC-related genes.

CONCLUSION

Given the high incidence of GC in Iran, changing lifestyle and decreasing consumption of preservatives in food, increasing consumption of fruits and vegetables, and improving the lifestyle can be effective in reducing the incidence of this disease.

Single Nucleotide Variants Associated with Colorectal Cancer Among Iranian Patients: A Narrative Review

Colorectal cancer has been considered as one of the complicated multi-stage processes after adenoma-carcinoma sequence. Therefore, studies of the molecular dysregulation basis could present information on the recognition of the potent biomarkers and treatment targets for this disease. Even though outcomes of the patients with colorectal cancer have been improved largely with current annual screening plans, it is necessary to have reliable prognostic biomarkers because of the disease heterogeneity. There is a significant relationship between SNP in IL1RN* 2 (IL1ra), −509 C/T (TGFB1), rs11556218 T>G and rs4778889 T/C (IL16), miRNA-binding site polymorphisms in IL16, rs4464148 (SMAD7), rs6983267 (EGF), GSTT1, TACG haplotype (CTLA4), 1793G> A (MTHFR), Leu/Leu genotype of (EXO1), −137 G/C (IL18), C/T genotype (XRCC3), I3434T (XRCC7), MGMT, C3435T (MDR1), ff genotype of FokI, 677CT+TT (MTHFR), G2677T/A (MDR1) and CRC. Increased risk has been observed in VDR ApaI genotype “aa”. Finally, the protective effect has been explored in the TACA haplotype (CTLA4). According to the findings, the genetic polymorphisms in the immunity-associated genes are related to the CRC amongst the Iranian patients. Therefore, more large-scale functional investigations are necessary for confirming the results.

Genetic polymorphisms of TP53 (rs1042522) and MDM2 (rs2279744) and colorectal cancer risk: An updated meta-analysis based on 59 case-control studies

OBJECTIVE

Several earlier reports implicated TP53 (rs1042522) and MDM2 (rs2279744) variants in outcome of colorectal cancer (CRC), but with inconclusive findings. This current meta-analysis designed to uncover the role of these variants in CRC risk.

METHODOLOGY

Two independent investigators extracted 59 eligible case-control studies from different electronic databases involving Scopus, Web of Science and PubMed prior to June 2019. Pooled odds ratios (ORs) and "95% confidence intervals (CIs)" were computed for different hereditary models. Stratification and heterogeneity analyses, and "Begg's funnel plots" were conducted. In silico data analyses of the functional and structural properties of the study variants were applied.

RESULTS

In general, 47 and 16 case-control reports for TP53 (11,589 patients and 13,622 controls) and MDM2 (6841 CRC patients and 8792 healthy controls), respectively were enrolled in this meta-analysis. A significant association of TP53 (rs1042522) variant with increased CRC risk in overall pooled subjects under recessive model [(CC vs. GC + GG, OR = 1.134, 95% CI = 1.006-1.278, P = 0.039)] was observed. Moreover, an evidence of MDM2 (rs2279744) association with increased CRC risk in overall pooled subjects under dominant and heterozygote models [(TG + GG vs. TT, OR = 1.120, 95% CI = 1.003-1.250, P = 0.044) and (TG vs. TT, OR = 1.189, 95% CI = 1.076-1.313, P = 0.001), respectively] was reported. Additionally, TP53 (rs1042522) and MDM2 (rs2279744) showed an association with CRC risk among Asians and Africans under a recessive model, and among Asians under different genetic models, respectively, by stratification analysis.

CONCLUSION

TP53 (rs1042522) and MDM2 (rs2279744) variants might represent candidate risk factors for CRC susceptibility.

Genetic polymorphisms of TP53 Arg72Pro and Pro47Ser among Egyptian patients with colorectal carcinoma

BACKGROUND

Previous reports demonstrated the role of TP53 gene polymorphisms with CRC risk among several ethnic populations. The purpose of this study is to assess the association of the TP53 Arg72Pro and Pro47Ser variants with CRC risk among Egyptian patients.

SUBJECTS AND METHODS

This work was conducted on 120 unrelated CRC Egyptian patients who were compared to 140 healthy controls. DNA was genotyped for these variants using the PCR-RFLP technique.

RESULTS

CRC patients observed a significant association of the rare genotype of TP53 Arg72Pro polymorphism compared with healthy controls. On the contrast, all genetic models showed no statistical association of TP53 Pro47Ser polymorphism among CRC patients compared with healthy controls. On the contrast, CRC patients of the TP53 gene polymorphisms indicated no significant difference regarding their clinical and laboratory markers.

CONCLUSIONS

Our findings indicate a strong association with TP53 Arg72Pro variant within increased risk of CRC among Egyptian patients.

Association of mRNA expression of TP53 and the TP53 codon 72 Arg/Pro gene polymorphism with colorectal cancer risk in Asian population: a bioinformatics analysis and meta-analysis

Background

The relationship between TP53 codon 72 Pro/Arg gene polymorphism and colorectal cancer risk in Asians is still controversial, and this bioinformatics analysis and meta-analysis was performed to assess the associations.

Methods

The association studies were identified from PubMed, and eligible reports were included. RevMan 5.3.1 software, Oncolnc, cBioPortal, and Oncomine online tools were used for statistical analysis. A random/fixed effects model was used in meta-analysis. The data were reported as risk ratios or mean differences with corresponding 95% CI.

Results

We confirmed that TP53 was associated with colorectal cancer, the alteration frequency of TP53 was 53% mutation and 7% deep deletion, and TP53 mRNA expression was different in different types of colorectal cancer based on The Cancer Genome Atlas database. Then, 18 studies were included that examine the association of TP53 codon 72 gene polymorphism with colorectal cancer risk in Asians. The meta-analysis indicated that TP53 Pro allele and Pro/Pro genotype were associated with colorectal cancer risk in Asian population, but Arg/Arg genotype was not (Pro allele: odds ratios [OR]=1.20, 95% CI: 1.06 to 1.35, P=0.003; Pro/Pro genotype: OR=1.39, 95% CI: 1.15 to 1.69, P=0.0007; Arg/Arg genotype: OR=0.86, 95% CI: 0.74 to 1.00, P=0.05). Interestingly, in the meta-analysis of the controls from the population-based studies, we found that TP53 codon 72 Pro/Arg gene polymorphism was associated with colorectal cancer risk (Pro allele: OR=1.33, 95% CI: 1.15 to 1.55, P=0.0002; Pro/Pro genotype: OR=1.61, 95% CI: 1.28 to 2.02, P<0.0001; Arg/Arg genotype: OR=0.77, 95% CI: 0.63 to 0.93, P=0.009).

Conclusion

TP53 was associated with colorectal cancer, but the different value levels of mRNA expression were not associated with survival rate of colon and rectal cancer. TP53 Pro allele and Pro/Pro genotype were associated with colorectal cancer risk in Asians.

The association between the TP53 Arg72Pro polymorphism and colorectal cancer: An updated meta-analysis based on 32 studies

Several previous studies evaluated the association between the Arg72Pro (rs1042522) polymorphism in the TP53 tumor suppressor gene and colorectal cancer (CRC). However, the results are conflicting. This meta-analysis aimed to shed new light on the precise association between TP53 variants and CRC. We analyzed 32 published case-control studies involving 8,586 cases and 10,275 controls using crude odd ratios (ORs) with 95% confidence intervals (CIs). The meta-analysis was performed using a fixed-effect or random-effects model, as appropriate. We found that the TP53 Arg72Pro polymorphism was not significantly associated with CRC risk in the overall population. However, subgroup analysis based on ethnicity revealed an increased risk of CRC among Asians (CC vs. GC+GG: OR=1.22, 95% CI: 1.02-1.45), and similar results were found for rectal cancer (CC vs. GC+GG: OR=1.34, 95% CI: 1.120-1.62). These results suggest that the TP53 Arg72Pro polymorphism CC genotype may contribute to an increased risk of CRC, especially for rectal cancer and among Asians.

Association of p53 codon 72 Arg>Pro polymorphism and risk of cancer in Iranian population: A systematic review and meta-analysis

Background: Different studies have investigated the association between p53 codon 72 Arg>Pro polymorphism and cancer risk. Because of the lack of consensus of the results in individual studies, we conducted this meta-analysis by pooling all currently available case-control studies to estimate the effect of p53 codon 72 Arg/Pro polymorphism on cancer susceptibility in Iranian population. Methods: A comprehensive search was undertaken and primary data from all peer-reviewed journals indexed in PubMed, Google Scholar, Scopus, Magiran, Scientific Information Databank (SID), Iran Medex, and CAB abstract electronic were used to conduct this meta-analysis. We considered some exclusion and inclusion criteria to select the articles. Statistical heterogeneity was explored using the I-square. Publication bias was assessed graphically and statistically by Begg's funnel plot and Egger test. All statistical analyses were performed using StatsDirect software and a two- tailed test. P-value less than 0.05 was considered statistically significant for any test. Results: Our dataset, which included 35 case-control studies, consisted of 2426 cancer cases and 2928 controls. Pooled OR and 95%CI indicated that codon 72 Arg>Pro polymorphism was not associated with odds of developing cancer among Iranian population in the dominant model (Pro/Pro+Arg/Pro vs. Arg/Arg: OR= 0.96, 95%CI= 0.74 to 1.24 chi2= 0.06, p= 0.8). Moreover, no significant association was detected in variant allele (Pro vs Arg: OR= 1.075, 95%CI= 0.91 to 1.25), homozygous (Pro/Pro vs Arg/Arg: OR=0.911 95%CI= 0.66 to 1.25), and heterozygous (Arg/Pro vs Arg/Arg: OR= 0.84, 95%CI= 0.7 to 1). Conclusion: Our study revealed that p53 codon 72 Arg>Pro polymorphism was not associated with overall cancer odds in Iranian population.

Association between the rs1042522 polymorphism in TP53 and prostate cancer risk: An updated meta-analysis

Objective

The proposal of the present study was to investigate whether the TP53 rs1042522 polymorphism confers susceptibility to prostate cancer (PCa), by performing an updated meta-analysis.

Methods

Eligible publications investigating the association between the TP53 rs1042522 polymorphism and PCa susceptibility were selected from PubMed, Google Scholar, and Web of Science. We used STATA 12.0 software to conduct the analyses. Odds ratio (OR) with 95% confidence interval (CI) was calculated.

Results

A total of 17 case–control studies were retrieved reporting a total of 2683 cases and 2981 controls. However, no significant association was uncovered between the TP53 rs1042522 polymorphism and PCa susceptibility in the overall population under the five genetic models. In the stratification analysis by source of control, an increased susceptibility to PCa was identified in the population-based (P-B) group (CG vs. GG: OR = 1.48, 95% CI: 1.24–1.77, P < 0.01; CC/CG vs. GG: OR = 1.32, 95% CI: 1.12–1.57, P < 0.01), whereas a decreased susceptibility was uncovered in the hospital-based (H-B) group (CG vs. GG: OR = 0.67, 95% CI: 0.46–0.96, P = 0.03; CC/CG vs. GG: OR = 0.67, 95% CI: 0.46–0.99, P = 0.04) under heterozygous and dominant model.

Conclusion

This study did not find an association between the TP53 rs1042522 polymorphism and PCa susceptibility in the overall population and corresponding subgroup analyses except in the stratification analysis by source of control. The results suggest that the TP53 rs1042522 polymorphism is not a risk factor for PCa.

Effects of p53 codon 72 and MDM2 SNP309 polymorphisms on gastric cancer risk among the Iranian population

BACKGROUND

Development of gastric cancer (GC) is a multistep process that requires alterations in the expression of oncogenes and tumor suppressor genes, occurring over several decades. The p53 tumor suppressor protein is involved in cell-cycle control, apoptosis and DNA repair. One of the most important regulators of p53 is MDM2, which acts as a negative regulator in the p53 pathway. Based on the key role of p53 and MDM2 in tumor suppression, polymorphisms that cause change in their function might affect cancer risk. We therefore elevated associations of the polymorphisms of p53 (R72P) and MDM2 (SNP309) with GC in Iran.

MATERIALS AND METHODS

A total of 104 patients with gastric cancer and 100 controls were recruited. Genomic DNA was extracted from fresh gastric samples. Genotyping of the p53 and MDM2 genes was performed using allele specific PCR (AS-PCR).

RESULTS

There was no significant difference between the p53 codon 72 polymorphism distribution in control and patient groups (p=0.54), but the G allele of MDM2 was found to be over-represented in patients (p=0. 01, Odds Ratio=2. 08, 95% Confidence Interval= 1.37-4.34).

CONCLUSIONS

The p53 R72P seems not to be a potential risk factor for development of GC among Iranian patients, but our data suggest that MDM2 SNP309 might modify the risk related to GC.

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.

Association between TLR2, MTR, MTRR, XPC, TP73, TP53 genetic polymorphisms and gastric cancer: a meta-analysis

OBJECTIVE

The aim of our meta-analyses is to test the association between six genetic polymorphisms and gastric cancer.

METHODS

A systematic search was performed for all the available candidate genes and gastric cancer among several online databases including PubMed, Embase, Web of Science, the Cochrane Library, CNKI and Wanfang online libraries. After a comprehensive screening, a total of six genes were harvested for the current meta-analyses. These genes include TLR2 (-196 to -174 ins>del), MTR (rs1805087), MTRR (rs1801394), XPC (rs2228001), TP73 (G4C14-A4T14), and TP53 (rs1042522).

RESULTS

Altogether 49 comparative studies among 11 776 cases and 18 633 controls were involved in our meta-analyses. TP53 rs1042522 polymorphism was shown to be associated with gastric cancer risk under the dominant model (P=0.02, OR=1.03, 95% CI=1.00-1.05). A subgroup meta-analysis indicated a significant association under dominant model between TP53 rs1042522 and gastric cancer in the Eastern Asians (P=0.03, OR=1.17, 95%=1.02-1.34).

CONCLUSIONS

These results suggest that TP53 rs1042522 polymorphism might contribute to the susceptibility of gastric cancer under the dominant model, especially in Eastern Asians.

Updated meta-analysis of the TP53 Arg72Pro polymorphism and gastric cancer risk

OBJECTIVE

The p53 tumor suppressor pathway plays an important role in gastric cancer (GC) development. Auto-regulatory feedback control of p53 expression is critical to maintaining proper tumor suppressor function. So far, several studies between p53 Arg72Pro polymorphism and GC have generated controversial and inconclusive results.

METHODS

To better assess the purported relationship, we performed a meta-analysis of 19 publications. Eligible studies were identified by searching the Pubmed database. Odds ratios (ORs) with 95% confidence intervals (CIs) were estimated to assess any link.

RESULTS

Overall, a significant association was detected between the p53 Arg72Pro polymorphism and GC risk (Pro-allele vs. Arg-allele: OR=1.05, 95%CI=1.01-1.08; Pro/Pro vs. Arg/Arg: OR=1.13, 95%CI=1.04-1.22). Moreover, on stratified analysis by race, significantly increased risk was found for Asian populations (Pro-allele vs. Arg-allele: OR=1.06, 95%CI=1.02-1.10; Pro/Pro vs. Arg/Arg: OR=1.16, 95%CI=1.07-1.26; Pro/Pro+Pro/Arg vs. Arg/Arg: OR=1.58, 95%CI=1.09-2.27).

CONCLUSIONS

Our study provided evidence that the p53 72Pro allele may increase GC risk in Asians. Future studies with larger sample size are warranted to further confirm this association in more detail.

Pro variant of TP53 Arg72Pro contributes to gastric cancer risk in Asians: evidence from a meta-analysis

BACKGROUND

Previous studies investigating the association between TP53 Arg72Pro polymorphism and gastric cancer (GC) risk in Asian population have reported controversial results. Thus, a meta-analysis was performed.

METHODS

A comprehensive literature search was conducted and 17 case-control studies were finally included, involving a total of 5,990 GC cases and 6,812 controls. Subgroup analyses were performed by the sample size.

RESULTS

Meta-analysis of all 17 studies showed variant genotypes of TP53 Arg72Pro to be associated with an elevated GC risk in three genetic comparison models (OR(Pro vs. Arg)=1.13, 95%CI 1.03-1.25, P(OR)=0.01; OR(Homozygote comparison model)=1.33, 95%CI 1.07-1.64, P(OR)=0.009; OR(Dominant genetic model)=1.13, 95%CI 1.05-1.22, P(OR)=0.002). Besides, a more obvious association was observed after the heterogeneity was decreased (all P values less than 0.001). This association was further identified by both subgroup and sensitivity analyses.

CONCLUSIONS

This meta-analysis suggests the Pro variant of TP53 Arg72Pro contributes to gastric cancer risk in Asians.

An updated meta-analysis of the p53 codon 72 polymorphism and gastric cancer risk

To investigate the association between p53 codon 72 polymorphisms and gastric cancer risk, a meta-analysis published in 2007 was updated with new data. Relevant literature was retrieved by searching PubMed and statistical analysis conducted using Review Manager software. Twenty-eight case-control studies were included in this meta-analysis, with 6,859 cases and 9,277 controls. The pooled results for all included studies showed that patients with gastric cancer had a borderline lower frequency of the Arg/Arg phenotype (odds ratio (OR) = 0.91, 95 % CI = 0.83-1.00, p = 0.04). When stratified for race, the difference in Arg/Arg frequency was significant among Asians (OR = 0.87, 95 % CI = 0.78-0.97, p = 0.01). On stratifying the various studies we found that, among Asians: (i) patients with cardial gastric cancer had a significantly higher frequency of the Pro/Pro genotype (OR = 1.35, 95 % CI = 1.03-1.77, p = 0.04) than those with non-cardial gastric cancer; (ii) patients with advanced (stage III/IV) gastric cancer had a significantly higher frequency of Arg/Arg (OR = 1.30, 95 % CI = 1.06-1.61, p = 0.01) than those with early (stage I/II) cancer; and (iii) patients with metastasis had a significantly higher frequency of Pro/Pro (OR = 3.31, 95 % CI = 1.31-8.41) than those without metastasis. Our study suggests that, among Asians, the p53 codon 72 Arg/Arg genotype is associated with a modestly decreased risk of gastric cancer, and that this difference in genotype distribution may be associated with cancer stage, location, differentiation and metastasis.

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.

TP53 codon 72 polymorphism and colorectal cancer susceptibility: a meta-analysis

Colorectal cancer constitutes a significant proportion of the global burden of cancer morbidity and mortality. A number of studies have been conducted to explore whether TP53 codon 72 polymorphism is associated with colorectal cancer susceptibility. However, controversial results were obtained. In order to derive a more precise estimation of the relationship, we systematically searched Medline, Google scholar, and Ovid database for studies reported before May 2010. A total of 3603 colorectal cancer cases and 5524 controls were included. TP53 codon 72 polymorphism was not associated with colorectal cancer risk in all genetic models (for dominant model: OR = 0.99, 95% CI: 0.86-1.15; for recessive model: OR = 1.00, 95% CI: 0.81-1.23; for Arg/Pro vs. Arg/Arg: OR = 1.00, 95% CI: 0.87-1.15; for Pro/Pro vs. Arg/Arg: OR = 0.97, 95% CI: 0.76-1.25). In the subgroup analyses by ethnic groups and sources of controls, no significant associations were found in all models. Taken together, this meta-analysis suggested that the biologically usefulness of TP53 codon 72 polymorphism as a selection marker in colorectal cancer susceptibility may be very limited.

Genetic mutations of p53 and k-ras in gastric carcinoma patients from Hunan, China

This case-control study investigated the mutations in p53 and k-ras genes of 123 gastric carcinoma patients and 129 normal individuals from Hunan, China. By isolating genomic DNA from peripheral blood and employing polymerase chain reaction-single strand conformation polymorphism and DNA sequencing, the mutations of p53 exons-5, 6, 7, and 8 and k-ras were detected. The overall mutation frequency of p53 was 29.3%, and mutation was found in all four exons studied. The point mutations were predominant and among them, G:C→A:T was the highest (41.7%), followed by A:T→G:C (25%), G:C→C:G (11.1%), G:C→T:A (8.3%), and A:T→T:A (2.8%). The frameshift mutation was 11.1%. Mutations were detected in codons-131, 132, 133, 135, 149, 151, 162, 167, 173, 174, and 175 of exon 5, codons-193, 197, 213, and 215 of exon 6, codons-245, 246, 248, 249, and 270 of exon 7, and codons-271, 272, 273, and 282 of exon 8 of p53. The overall frequency of mutation in k-ras was 9.8%, mostly in codon-12 (91.7%) and in codon-13 (8.3%). There was no significant relationship between p53 and k-ras gene mutation in gastric carcinoma patients. Also, the relationships between p53 mutation and age, sex, smoking or drinking, and tumor metastasis were not significant. However, the patients with high/high-middle differentiated gastric carcinoma had a higher association with of p53 mutations. This study identified some novel p53 mutations in gastric cancer and showed mutation pattern and frequency of p53 and k-ras in the population of the central southern region of China.

Systematic review and meta-analysis of the association between P53 codon 72 polymorphism and colorectal cancer

BACKGROUND

A number of studies has evaluated the association between P53 codon 72 polymorphism and colorectal cancer. However, results were inconsistent. To clarify the role of this polymorphism in colorectal cancer, we conducted a meta-analysis on this topic.

METHODS

Two authors independently searched the PubMed and EMBASE database from 1966 to January 2010 for studies regarding the association of P53 codon 72 polymorphism with colorectal cancer. Summary odds ratios with their corresponding 95% confidence intervals were calculated by using random-effects model.

RESULTS

The combined results showed that P53 codon 72 variant genotypes were not associated with colorectal cancer risk when compared to Arg/Arg genotype (Pro/Pro: OR = 1.02, 95% CI = 0.80-1.29; Arg/Pro: OR = 1.00, 95% CI = 0.86-1.16; Pro allele: OR = 1.00, 95% CI = 0.86-1.17). When stratifying for study population, design and cancer location, no statistically significant results were observed either.

CONCLUSION

Our data indicate that the P53 codon 72 polymorphism may be not associated with colorectal cancer risk.