Alterations in exon 4 of the p53 gene in gastric carcinoma

Systematic Review and Meta-analysis of TP53, HER2/ERBB2, KRAS, APC, and PIK3CA Genes Expression Pattern in Gastric Cancer

Background: With a global prevalence of about 10%, gastric cancer is among the most prevalent cancers. Currently, there has been an ongoing trend toward investigating genetic disruptions in different cancers because they can be used as a target-specific therapy. We aimed to systemically review some gene expression patterns in gastric cancer. Methods: The current systematic review was designed and executed in 2020. Scopus, PubMed, Cochrane Library, Google Scholar, web of knowledge, and Science Direct were searched for relevant studies. A manual search of articles (hand searching), reference exploring, checking for grey literature, and seeking expert opinion were also done. Results: In this review, 65 studies were included, and the expression pattern of HER2/ ERBB2, ER1/Erb1/EGFR, PIK3CA, APC, KRAS, ARID1A, TP53, FGFR2 and MET was investigated. TP53, APC, KRAS, and PIK3CA mutation cumulative frequency were 24.8 (I²=95.05, Q value=525.53, df=26, P<0.001), 7.2 (I²=89.79, Q value=48.99, df=5, P<0.001), 7.8 (I²=93.60, Q value=140.71, df=9, P=0.001) and 8.6 (I²=80.78, Q value=525.53, df=9, P<0.001) percent, respectively. Overexpression was investigated for HER1/ Erb1/EGFR, PIK3CA, APC, KRAS, ARID1A, TP53, CCND1, FGFR2, MET and MYC. The frequency of TP53 and HER2/ERBB2 were 43.1 (I²=84.06, Q value=58.09, df=9, P<0.001) and 20.8 (I²=93.61, Q value=234.89, df=15, P<0.001) percent, respectively. Conclusion: More research is encouraged to investigate the genes for which we could not perform a meta-analysis.

Isoforms of the p53 Family and Gastric Cancer: A Ménage à Trois for an Unfinished Affair

Simple Summary

The p53 family is a complex family of transcription factors with different cellular functions that are involved in several physiological processes. A massive amount of data has been accumulated on their critical role in the tumorigenesis and the aggressiveness of cancers of different origins. If common features are observed, there are numerous specificities that may reflect particularities of the tissues from which the cancers originated. In this regard, gastric cancer tumorigenesis is rather remarkable, as it is induced by bacterial and viral infections, various chemical carcinogens, and familial genetic alterations, which provide an example of the variety of molecular mechanisms responsible for cell transformation and how they impact the p53 family. This review summarizes the knowledge gathered from over 40 years of research on the role of the p53 family in gastric cancer, which still displays one of the most elevated mortality rates amongst all types of cancers.

Abstract

Gastric cancer is one of the most aggressive cancers, with a median survival of 12 months. This illustrates its complexity and the lack of therapeutic options, such as personalized therapy, because predictive markers do not exist. Thus, gastric cancer remains mostly treated with cytotoxic chemotherapies. In addition, less than 20% of patients respond to immunotherapy. TP53 mutations are particularly frequent in gastric cancer (±50% and up to 70% in metastatic) and are considered an early event in the tumorigenic process. Alterations in the expression of other members of the p53 family, i.e., p63 and p73, have also been described. In this context, the role of the members of the p53 family and their isoforms have been investigated over the years, resulting in conflicting data. For instance, whether mutations of TP53 or the dysregulation of its homologs may represent biomarkers for aggressivity or response to therapy still remains a matter of debate. This uncertainty illustrates the lack of information on the molecular pathways involving the p53 family in gastric cancer. In this review, we summarize and discuss the most relevant molecular and clinical data on the role of the p53 family in gastric cancer and enumerate potential therapeutic innovative strategies.

Polymorphism at Codon 72 of the p53 Gene Is Not associated With Endometriosis in a Japanese Population

OBJECTIVE

Endometriosis is inherited as a complex trait, which means that multiple susceptibility genes interact with each other and the environment to produce the phenotype. Previous studies have implicated p53, a tumor suppressor gene, as a factor in the development of the disease. In a Japanese population, we investigated the frequency of the p53 polymorphism in women affected with endometriosis.

METHODS

We compared the distribution of the p53 codon 72 polymorphism in endometriosis cases (n = 111) and population controls consisting of female neonates (n = 180) by using polymerase chain reaction restriction fragment-length polymorphism analysis in a Japanese population.

RESULTS

The frequencies of the three p53 genotypes, Arginine (Arg)/Arg, Arg/Proline (Pro), and Pro/Pro in controls were 39.4%, 41.7%, and 18.9 %, respectively. The crude genotype frequencies in the endometriosis cases were similar to those of the controls (35.2%, 48.6%, and 16.2%, respectively). Using the Arg/Arg genotype as the reference, the odds ratios of the Arg/Pro and Pro/Pro genotypes were 1.30 (95% confidence interval [CI] 0.72-1.86, P =.33) and 0.96 (95% CI 0.47-1.94, P =.91), respectively. Thus, there were no significant differences in the frequency of the p53 codon 72 polymorphism between endometriosis cases and controls in this population. The endometriosis cases with severe disease only were also evaluated, but no significant difference was observed in the frequency of the polymorphism between this subgroup and the controls.

CONCLUSION

Our findings suggest that the p53 codon 72 polymorphism is unlikely to be associated with endometriosis in Japanese women.

Helicobacter pylori infection and a P53 codon 72 single nucleotide polymorphism: a reason for an unexplained Asian enigma

AIM

P53, the most commonly mutated tumor suppressor gene in all types of human cancer, is involved in cell cycle arrest and control of apoptosis. Although p53 contains several polymorphic sites, the codon 72 polymorphism is by far more common. There are divergent reports but many studies suggest p53 pro/pro SNP may be associated with susceptibility to developing various cancers in different regions of the world. The present study aimed to find any correlation between H. pylori infection and progression of carcinogenesis, by studying apoptosis and the p53 gene in gastric biopsies from north Indian population.

MATERIALS AND METHODS

A total of 921 biopsies were collected and tested for prevalence of H. pylori by rapid urease test (RUT), imprint cytology and histology. Apoptosis was studied by the TUNEL method. Analysis of p53 gene polymorphism at codon 72 was accomplished by PCR using restriction enzyme BstU1.

OBSERVATION

Out of 921 samples tested 56.7% (543) were H. pylori positive by the three techniques. The mean apoptotic index (AI) in the normal group was 2.12, while gastritis had the maximum 4.24 followed by gastric ulcer 2.28, gastropathy 2.22 and duodenal ulcer 2.08. Mean AI in cases with gastric cancer (1.72) was less than the normal group. The analysis of p53 72 SNP revealed that p53 (Arg/Arg), (Pro /Arg) variant are higher (40.59% and 33.66%) as compared to p53 pro/pro variant (25.74%) in the healthy population.

CONCLUSIONS

The North Indian population harbors Arg or Pro/Arg SNP that is capable of withstanding stress conditions; this may be the reason of low incidence of gastric disease in spite of high infection with H. pylori. There was no significant association with H. pylori infection and AI. However, there is increased apoptosis in gastritis which may occur independent of H. pylori or p53 polymorphism.

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 of p53 codon 72 polymorphism with prostate cancer: an update meta-analysis

Many studies have been conducted to explore the association between p53 codon 72 polymorphism and prostate cancer (PCa). However, the results remain inconsistent. Therefore, we performed a large meta-analysis of relevant studies to determine a more precise estimation of this relationship. Systematic searches of the electronic databases PubMed, EMBASE, Cochrane Library, and China National Knowledge Infrastructure (CNKI) up to October 2013 were performed. Fixed or random-effects meta-analytical models were used to calculate the summary odds ratio (OR) and corresponding 95% confidence intervals (CIs). Meta-regression, Galbraith plots, subgroup analysis, and sensitivity analysis were also performed. The study included 17 case-control studies involving 2,371 PCa cases and 2,854 controls. Our results showed that the p53 codon 72 polymorphism was not associated with PCa risk in all genetic models in the overall populations. When limiting the meta-analysis to the studies conforming to Hardy-Weinberg equilibrium, the pooled analyses showed a significant association between p53 codon 72 polymorphism and PCa in a Caucasian population in co-dominant model Pro/Pro vs. Arg/Arg (OR = 1.57, 95% CI = 1.08-2.28, P = 0.017) and recessive model Pro/Pro vs. (Arg/Pro + Arg/Arg) (OR = 1.60, 95% CI = 1.12-2.27, P = 0.009). In subgroup analysis stratified by PCa stages and Gleason grades, a slight but significant association was found when advanced PCa was compared with localized PCa only in recessive model Pro/Pro vs. (Arg/Pro + Arg/Arg) (OR = 1.51, 95% CI = 1.02-2.23, P = 0.039). This meta-analysis suggested that the Pro/Pro genotype of p53 codon 72 polymorphism was associated with increased prostate cancer risk, especially among Caucasians.

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.

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.

p53 codon 72 polymorphism in patients with gastric and colorectal cancer in a Korean population

BACKGROUND

The common p53 codon 72 polymorphism has been investigated as a risk factor for cancer in different populations; however, the results have been inconsistent. This study investigated the risk of developing gastric or colorectal cancer associated with the p53 codon 72 polymorphism in a Korean population.

METHODS

We conducted a large-scale case-control study that included 2,213 gastric cancer patients; 1,829 colorectal cancer patients; and 1,700 healthy controls. Genotyping was performed with real-time polymerase chain reaction (PCR), using a TaqMan single-nucleotide polymorphism (SNP) genotyping assay.

RESULTS

The frequencies of Arg/Arg, Arg/Pro, and Pro/Pro genotypes of the p53 codon 72 polymorphism were 43.3, 42.0, and 13.0% in the gastric cancer patients; 40.5, 45.0, and 14.0% in the colorectal cancer patients; and 43.2, 45.6, and 11.2% in the controls, respectively. The Pro/Pro genotype was associated with an increased risk of gastric [age- and sex-adjusted odds ratio (OR) = 1.25, 95% confidence interval (CI) = 1.01-1.56, P = 0.04] and colorectal cancer (OR = 1.36, 95% CI = 1.07-1.72, P = 0.01). There were no significant interactions between the p53 codon 72 polymorphism and smoking or drinking.

CONCLUSIONS

Our results suggest that the Pro/Pro genotype is associated with modest increases in the risks of gastric cancer and colorectal cancer in a Korean population.

p53 codon 72 polymorphism is associated with susceptibility to hepatocellular carcinoma in the Turkish population: a case-control study

The tumor suppressor p53 gene plays a crucial role in preventing carcinogenesis through its ability to induce cell cycle arrest and apoptosis following DNA damage and oncogene activation. A guanine (G)/cytosine (C) common single nucleotide polymorphism (SNP) at second position of codon 72 in exon 4 of p53 gene determines a arginine (Arg) to proline (Pro) (Arg72Pro) aminoacidic substitution within the proline-rich domain of p53 protein. Arg72 and Pro72 allele are different from a biochemical and biological point of view and many reports suggest that they can modulate individual cancer susceptibility. To determine the association of the p53 Arg72Pro polymorphism with the risk of hepatocellular carcinoma (HCC) development in a Turkish population, a hospital-based case-control study was designed consisting of 119 subjects with HCC and 119 cancer-free control subjects matched for age, gender, smoking and alcohol status. The genotype frequency of the p53 Arg72Pro polymorphism was determined by using a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay. Our data shows that the Pro/Pro genotype of the p53 Arg72Pro polymorphism is associated with increased risk of HCC development in this Turkish population (OR = 3.20, 95% CI: 1.24-8.22, P = 0.02). Furthermore, according to stratified analysis, a significant association was observed between the homozygote Pro/Pro genotype and HCC risk in the subgroups of male gender (OR = 3.01, 95% CI: 1.14-7.97, P = 0.03) and patients with hepatitis B virus (HBV)-related HCC (OR = 4.04, 95% CI: 1.46-11.15, P = 0.007). Because our results suggest for the first time that the Pro/Pro homozygote of p53 Arg72Pro polymorphism may be a genetic susceptibility factor for HCC (especially in the male gender and HBV-infected patients) in the Turkish population, further independent studies are required to validate our findings in a larger series, as well as in patients of different ethnic origins.

Study on the association of p53 codon 72 polymorphisms with risk of gastric cancer in high incidence Hexi area of Gansu Province in China

To investigate the possible association of P53 codon 72 Arg/Pro polymorphisms with risk of gastric cancer in the high incidence Hexi area of Gansu province in China. Blood samples from 140 patients with gastric carcinoma and 125 healthy controls were collected in Hexi area of Gansu province. Polymorphism of P53Arg72Pro was genotyped by PCR-TaqMan. For detection Helicobacter pylori infection, Warhin-Starry staining was used. Three kinds of polymorphisms of P53Arg72Pro were Arg/Arg, Arg/Pro, Pro/Pro. The frequencies in gastric cancer group were 15.7, 60.0, 24.3%, and the frequencies in healthy controls were 25.6, 54.4, 20.0%, respectively. P53 codon 72 Pro carrier genotype (Arg/Pro+Pro/Pro) increased risk of gastric carcinoma with an odds ratio 1.840 (95% CI: 1.006-3.387). Helicobacter pylori infection rate was 68.6% in patients group and 50.4% in healthy controls. Helicobacter pylori infection rate in gastric cancer patients was remarkably higher than that in the controls (OR: 2.147, 95% CI: 1.302-3.541, P=0.003). Stratification analysis showed that P53 codon 72 Pro carrier genotype with Helicobacter pylori infection was significantly higher in cases than that in the controls (OR: 4.182, 95% CI: 1.850-9.454). P53Arg72Pro polymorphisms could be a risk factor for gastric cancer in high incidence Hexi area of Gansu Province in China. P53 codon 72 Pro carrier genotype and Helicobacter pylori positive infection may have a synergistic effect on gastric cancer in high incidence Hexi area of Gansu Province in China.

p53 codon 72 polymorphism and liver cancer susceptibility: A meta-analysis of epidemiologic studies

AIM: To evaluate the association between p53 codon 72 polymorphism and liver cancer risk by means of meta-analysis.

METHODS: Two investigators independently searched the Medline, Embase and Chinese Biomedicine databases. Summary odds ratios and 95% CI for p53 codon 72 polymorphism and liver cancer were calculated in fixed-effects model (Mantel-Haenszel method) and random-effects model (DerSimonian and Laird method) when appropriate.

RESULTS: This meta-analysis included 1115 liver cancer cases and 1778 controls. The combined results based on all studies showed that there was a statistically significant link between Pro/Pro genotype and liver cancer, but not between Arg/Arg or Pro/Arg genotype and liver cancer. When stratifying for race, similar results were obtained, i.e. patients with liver cancer had a significantly higher frequency of Pro/Pro genotype than non-cancer patients among Asians. After stratifying the various studies by control source, gender, family history of liver cancer and chronic hepatitis virus infection, we found that (1) patients among hospital-based studies had a significantly higher frequency of Pro/Pro and a significantly lower frequency of Arg/Arg genotype than individuals without cancer; (2) female patients with liver cancer had a significantly lower frequency of Arg/Arg and a higher frequency of Pro/Arg+Pro/Pro genotypes than female individuals without cancer; (3) subgroup analyses for family history of liver cancer did not reveal any significant association between p53 codon 72 polymorphism and liver cancer development; and (4) patients with negative hepatitis virus infection had a significantly higher frequency of Pro/Pro and a significantly lower frequency of Arg/Arg genotype than individuals without cancer.

CONCLUSION: This meta-analysis suggests that the p53 codon 72 polymorphism may be associated with liver cancer among Asians.

p53 Pro72Arg polymorphism and prostate cancer in men of African descent

BACKGROUND

p53 is a transcription factor that regulates the cell cycle, DNA repair, and apoptosis. A variant at codon 72, rs1042522, results in altered activities for p53 and is, notably, differentially distributed among different ethnic populations. However, associations of this variant with cancer in men of African descent have not been explored. Herein, we tested the hypothesis that rs1042522 was associated with prostate cancer (PCa) risk.

MATERIALS AND METHODS

Genotypes were determined by PCR-RFLP methods in a study population of African descent consisting of 266 PCa patients and 196 male controls.

RESULTS

Our results indicate that the p53 polymorphism may be associated with increased risk of PCa. Genotypes were significantly and marginally associated with PCa risk using the dominant and log-additive genetic models (OR=1.53, 95% CI: 1.02-2.29, P=0.04; OR=1.33, 95% CI: 0.99-1.78, P=0.06, respectively). After adjusting for age, the associations with PCa remained, but results were not statistically significant (OR=1.48, 95% CI: 0.95-2.31, P=0.08; OR=1.30, 95% CI: 0.95-1.80, P=0.10, respectively).

CONCLUSIONS

The present study demonstrates that population-dependent differences in allele frequencies associated with health disparities provide a valuable framework for the interrogation of complex diseases in all populations.

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.

p53 Codon 72 polymorphism and gastric cancer risk in a Chinese Han population

BACKGROUND

studies investigating the association between p53 codon 72 polymorphism and gastric cancer risk report conflicting results. Our recent meta-analysis suggests that the p53 codon 72 polymorphism may be associated with gastric cancer among Asians.

AIM

the objective of this study was to investigate the association between p53 codon 72 polymorphism and gastric cancer risk in Chinese Han patients.

METHODS

we extracted the peripheral blood samples from 150 patients with gastric cancer and 150 control subjects. Polymerase chain reaction-restriction fragment length polymorphism analysis was performed to detect p53 codon 72 polymorphism in these patients.

RESULTS

patients with gastric cancer had a significantly lower frequency of Arg/Arg (odds ratio [OR] = 0.48, 95% confidence interval [95% CI] = 0.28, 0.80; p = 0.005) than control subjects. Patients with cardia gastric cancer had a significantly higher frequency of Pro/Pro (OR = 2.26, 95% CI = 1.12, 4.55; p = 0.02) than those with noncardia gastric cancer. Patients with advanced gastric cancer had a significantly higher frequency of Arg/Arg (OR = 2.66, 95% CI = 1.06, 6.65; p = 0.03) than those with early gastric cancer. When stratified by the Lauren's classification, histological differentiation of gastric cancer, no statistically significant result was observed.

CONCLUSION

this study suggests that the p53 codon 72 polymorphism may be associated with gastric cancer in Chinese Han patients, and that difference in genotype distribution may be associated with the location and stage of gastric cancer.

The discrepancy between genetic polymorphism of p53 codon 72 and the expression of p53 protein in Helicobacter pylori-associated gastric cancer in Korea

The p53 gene has been referred to as 'the guardian of the genome' because it controls apoptosis and cell cycle arrest. The purpose of this study was to evaluate the association of p53 codon 72 genetic polymorphism and the p53 immunohistochemistry with Helicobacter pylori-associated gastroduodenal diseases, including gastric cancer. This study included 1,852 subjects: controls and patients with gastric cancer, dysplasia, benign gastric ulcers, and duodenal ulcers (DU). Biallelic polymorphism was genotyped by restriction fragment length polymorphism. Immunohistochemical analysis for the detection of mutant type p53 expression was performed. The frequency of the Pro/Pro allele of the p53 codon 72 was higher in the patients with H. pylori-positive dysplasia than in controls (OR: 2.3, 95% CI: 1.3-4.3), but it was less frequent among patients with a H. pylori-positive DU (OR: 0.5, 95% CI: 0.3-0.8). However, there was no significant association with gastric cancer, including the location, stage, or histological type of gastric cancer. Expression of a mutant type of p53 protein was detected in 6.3% of dysplastic tissues and 26.5% of cancerous tissues compared 0% in the controls. Positive expression was higher in the intestinal type of cancer (34.9%) than in the diffuse type (15.0%; P = 0.001). These results suggest that genetic polymorphism of p53 codon 72 played a role in the determination of H. pylori-associated gastroduodenal diseases, but p53 immunostaining did not correlate with those of the p53 genetic polymorphism analysis.

Association of P53 Arg72Pro polymorphism and Helicobacter pylori infection with risk of gastric cancer in a high incidence area in China

AIM: To evaluate the association of P53 Arg72Pro polymorphism and Helicobacter pylori (H. pylori) infection with risk of gastric cancer in high-incidence Hexi area of Gansu province in China.

METHODS: Blood samples were collected from 140 patients with gastric carcinoma and 125 normal individuals in Hexi area in Gansu Province. Genomic DNA was extracted by proteinase K digestion followed by the saturated hydroxybenzene/chloroform procedure. The polymorphism of P53 Arg72Pro was genotyped by real-time PCR (TaqMan). For detection of H. pylori infection, Warthin-Starry staining was performed.

RESULTS: The rates of H. pylori infection were 68.6% in gastric carcinoma patients and 50.4% in healthy controls, with a significant difference between the two groups of patients (OR = 2.147, 95%CI: 1.302-3.541). Three genotypes of P53 Arg72Pro were identified: Arg/Arg, Arg/Pro and Pro/Pro. The frequencies of these three genotypes were 15.7%, 60.0% and 24.3% in gastric cancer patients, and 25.6%, 54.4% and 20.0% in normal controls, respectively. Compared with the Arg/Arg genotype, the frequency of Arg/Pro or Pro/Pro genotype showed no significant difference between cancer patients and normal controls. However, the frequency of P53 Arg72Pro Pro carrier genotype (Arg/Pro and Pro/Pro) in gastric cancer patients was significantly higher than that in normal controls (OR = 1.846, 95%CI: 1.006-3.387). Stratification analysis indicated that the P53 Arg72Pro Pro carrier genotype with H. pylori infection or with smoking increased the risk of gastric cancer.

CONCLUSION: P53 Arg72Pro polymorphism is associated with the risk of gastric cancer in high-incidence Hexi area of Gansu province in China. P53 Arg72Pro Pro carrier genotype with H. pylori infection or with cigarette smoking increases the risk of gastric cancer.

A systematic review of meta-analyses on gene polymorphisms and gastric cancer risk

BACKGROUND

Individual variations in gastric cancer risk have been associated in the last decade with specific variant alleles of different genes that are present in a significant proportion of the population. Polymorphisms may modify the effects of environmental exposures, and these gene-environment interactions could partly explain the high variation of gastric cancer incidence around the world. The aim of this report is to carry out a systematic review of the published meta-analyses of studies investigating the association between gene polymorphisms and gastric cancer risk, and describe their impact at population level. Priorities on the design of further primary studies are then provided.

METHODS

A structured bibliographic search on Medline and EMBASE databases has been performed to identify meta-analyses on genetic susceptibility to gastric cancer, without restriction criteria. We report the main results of the meta-analyses and we describe the subgroup analyses performed, focusing on the detection of statistical heterogeneity. We investigated publication bias by pooling the primary studies included in the meta-analyses, and we computed the population attributable risk (PAR) for each polymorphism.

RESULTS

Twelve meta-analyses and one pooled-analysis of community based genetic association studies were included, focusing on nine genes involved in inflammation (IL-1beta, IL-1RN, IL-8), detoxification of carcinogens (GSTs, CYP2E1), folate metabolism (MTHFR), intercellular adhesion (E-cadherin) and cell cycle regulation (p53). According to their random-Odds Ratios, individuals carrying one of the IL-1RN *2, IL-1beta -511T variant alleles or homozygotes for MTHFR 677T are significantly at higher risk of gastric cancer than those with the wild type homozygote genotypes, showing high PARs. The main sources of heterogeneity in the meta-analyses were ethnicity, quality of the primary study, and selected environmental co-exposures. Effect modification by Helicobacter pylori infection for subjects carrying the unfavourable variant of IL-1 polymorphisms and by low folate intake for individuals homozygotes for MTHFR 677T allele has been reported, while genes involved in the detoxification of carcinogens show synergistic interactions. Publication bias was observed (Egger test, p = 0.03).

DISCUSSION

The published meta-analyses included in our systematic review focused on polymorphisms having a small effect in increasing gastric cancer risk per se. Nevertheless, the risk increase by interacting with environmental exposures and in combination with additional unfavourable polymorphisms. Unfortunately meta-analyses are underpowered for many subgroup analyses, so additional primary studies performed on larger population and collecting data on environmental and genetic co-exposures are demanded.

Difference of p53AIP1 mRNA expression in gastric mucosa between patients with gastric cancer and chronic gastritis infected with Helicobacter pylori

GOALS

To examine the significance of alteration of p53-regulated apoptosis-induced protein 1 (p53AIP1) expression in gastric carcinogenesis in patients with Helicobacter pylori infection.

BACKGROUND

H. pylori infection induces gastric mucosal inflammation and DNA damage of epithelial cells, which associate with gastric carcinogenesis. p53AIP1 is expressed after DNA damage and induces apoptosis in human cell lines.

STUDY

Endoscopic antral and corpus biopsies were obtained from 13 patients with chronic gastritis and 17 with gastric cancer. Expression of p53AIP1 and p53DINP1 mRNA was examined by semiquantitative reverse transcription polymerase chain reaction and mutation of p53 codon-46 was studied by direct sequence analysis. The grade of gastritis was assessed according to the updated Sydney System. Results were compared between patients with gastric cancer and chronic gastritis.

RESULTS

In the antrum, p53AIP1 mRNA expression was significantly lower in patients with gastric cancer than in those with chronic gastritis (P<0.05). In patients with chronic gastritis, expression of p53AIP1 mRNA was significantly higher in the antrum than in the corpus (P<0.05). In patients with chronic gastritis, antral mucosa with high p53AIP1 expression tended to have severe intestinal metaplasia. No mutation was found at p53 codon-46.

CONCLUSIONS

In H. pylori-infected gastric mucosa expression of p53AIP1 would be higher when the inflammation is severe or intestinal metaplasia is present. Insufficient expression of p53AIP1 may play a role in gastric carcinogenesis in patients infected with H. pylori infection.

P53 codon 72 polymorphism and gastric cancer: a meta-analysis of the literature

Studies investigating the association between p53 codon 72 polymorphism and gastric cancer risk report conflicting results. The objective of this study was to quantitatively summarize the evidence for such a relationship. Two investigators independently searched the Medline and Embase databases. This meta-analysis included 12 case-control studies, which included 1,665 gastric cancer cases and 2,358 controls. The combined results based on all studies showed that there was no significant difference in genotype distribution [Arg/Arg odds ratio (OR) = 0.96, 95% confidence interval (CI) = 0.79, 1.16; Pro/Pro (OR = 1.21, 95% CI = 0.92, 1.58); Pro/Arg (OR = 0.95, 95% CI = 0.79, 1.14)] between gastric cancer and noncancer patients. When stratifying for race, results were similar except that patients with gastric cancer had a significantly lower frequency of Arg/Arg (OR = 0.84, 95% CI = 0.72, 0.99) than noncancer patients among Asians. Stratified the various studies by the location, stage, Lauren's classification, and histological differentiation of gastric cancer, we found that (i) patients with cardia gastric cancer had a significantly higher frequency of Pro/Pro (OR = 3.20, 95% CI = 1.46,7.01) than those with noncardia gastric cancer among Asians; (ii) patients with advanced (stage III/IV) gastric cancer had a significantly higher frequency of Arg/Arg (OR = 1.48, 95% CI = 1.01, 2.16) than those with early (stage I/II) gastric cancer among Asians; (iii) patients with poor differentiation had a significantly lower frequency of Pro/Pro (OR = 0.13, 95% CI = 0.03, 0.64) than those with well differentiation among Caucasians. This meta-analysis suggests that the p53 codon 72 polymorphism may be associated with gastric cancer among Asians, and that difference in genotype distribution may be associated with the location, stage, and histological differentiation of gastric cancer.

Transgastric access by balloon overtube for intraperitoneal surgery

The final frontier in endoscopy is the peritoneal cavity which was recently reached through natural orifice transluminal endoscopic surgery (NOTES). Endoscopic perforation caused by NOTES has been the major challenge for this procedure because of the risk of peritonitis and consequent complications. We describe in a dog model the use of an overtube system, one of them with a balloon, to access the peritoneal cavity by NOTES. It permits direct access to the peritoneal cavity from the mouth and also allows the performance of a controlled perforation and provides conditions for a safe closure of the gastric wall.

No association between p53 gene intron 7 polymorphism and chronic atrophic gastritis in Han Chinese of Jiangsu province

AIM: To explore whether the polymorphism of p53 gene intron 7 is associated with the occurrence of chronic atrophic gastritis (CAG) in Han Chinese of Jiangsu province.

METHODS: The genome DNA was extracted from tissues of 80 CAG patients and 76 healthy controls, and the exon 7 and 8 as well as the intron 7 within exon 7 and 8 of p53 gene were amplified by polymerase chain reaction (PCR). The products were sequenced after purification. The polymorphism of p53 gene intron 7 was comparatively analyzed with the standard sequences. The genotypes and allelic frequencies compared between the two groups using chi-square test.

RESULTS: In CAG cases, the allelic frequencies of the 72^th base pair (bp) and the 92^th bp in p53 gene intron 7 were 32.5% (T-G) and 67.5% (C-T), and the frequencies of genotype T-G/T-G, C-T/T-G, and C-T/C-T were 11.3%, 42.5%, and 46.3%, respectively. Meanwhile in the controls, the allelic frequencies of T-G and C-T were 29.6% and 70.4%, and the frequencies of genotype T-G/T-G, C-T/T-G, and C-T/C-T were 9.2%, 40.8%, and 50.0%, respectively. There were no significant differences in the allelic frequencies and genotypic distributions between the two groups (P > 0.05). The risk of CAG occurrence was not significantly different between the individuals with T-G and C-T allele (OR = 1.14).

CONCLUSION: There is no direct association between the polymorphism of p53 gene intron 7 and epigenetic penetrance of CAG in Han Chinese of Jiangsu province.

Per-oral transgastric abdominal surgery

Laparoscopic surgery has several advantages over traditional surgery because it has been shown to be less invasive. The next logical step in the evolution of minimally invasive surgery may be to eliminate all abdominal incisions. The natural orifices provide a port of entry via the gastrointestinal tract to the peritoneal cavity. This approach would require the creation of a perforation, which is considered to be a major complication of endoscopy with significant morbidity and mortality. However, there are several recent studies that have described the technical feasibility and safety of a per-oral transgastric approach to the peritoneal cavity using conventional endoscopes. Theoretically, this approach could reduce postoperative abdominal wall pain, wound infection, hernia formation, and adhesions. This article aims to summarize the current status of transgastric surgery, currently referred to as natural orifice transluminal endoscopic surgery (NOTES), and to address some of its future challenges.

A p53 genetic polymorphism of gastric cancer: Difference between early gastric cancer and advanced gastric cancer

AIM: To investigate the role of the polymorphism of p53 codon 72 in early gastric cancer (EGC) and advanced gastric cancer (AGC) in Korean patients.

METHODS: DNA was extracted from blood samples of gastric cancer patients (n = 291) and controls (n = 216). In the p53 codon 72 genotypes were determined by PCR-RFLP.

RESULTS: Patients with gastric cancer had a significantly higher frequency of the homozygous proline (Pro) allele than the control (P = 0.032). Patients with AGC had a significantly higher frequency of the Arg/Arg (arginine) allele (P = 0.038) than EGC and a similar Pro/Pro allele. The signet ring cell type had a higher frequency of the Pro/Pro allele than other types (P = 0.031). The Pro/Pro genotype carries a 3.9-fold increased risk of developing gastric cancer (95% CI, 1.3-15.4, P = 0.039) when compared to Arg/Arg and Arg/Pro genotypes and to develop EGC is a 5.25 fold increased risk (95% CI, 1.8-19.6, P = 0.021).

CONCLUSION: The Pro/Pro genotype of the p53 codon 72 polymorphism carries a higher risk for gastric cancer in general and is also associated with a much higher risk for EGC than AGC.

P53 genetic polymorphism of gastric cancer in Korea

BACKGROUND

Deletion or functional loss of the p53 tumor suppression gene plays a role in oncogenic transformation. The codon 72 polymorphism on exon 4 in the p53 gene produces variant proteins with either arginine (Arg) or proline (Pro), and is associated with an increased susceptibility of cancers of the lung, esophagus, breast, cervix and nasopharynx on a genetic basis. We designed this study to evaluate the influence of the p53 codon 72 polymorphism on gastric cancer in Korea.

METHODS

We extracted the peripheral blood samples in 84 patients with gastric cancer, 66 patients with H. pylori-associated chronic gastritis and 43 controls without H. pylori infection. PCR-RFLP analysis was performed to detect p53 codon 72 polymorphism in these patients.

RESULTS

There was no specific genotype of p53 polymorphism in the gastric cancer group compared to the other groups and no difference in genotypes by histologic subtypes. Classified by tumor location, Pro/Pro genotype was associated with an increase in proximal cancer and Arg/Arg genotype with distal cancer. As the frequency of p53 Arg allele increased, the cancer was of a more poorly differentiated type.

CONCLUSIONS

The specific genotype of p53 polymorphism seems to correlate with tumor location. Increased frequency of p53 Arg allele is associated with more poorly differentiated cancers.

P53 Codon 72 polymorphisms: a case-control study of gastric cancer and potential interactions

P53 codon 72 polymorphisms have been reported to be associated with cancers of the lung, esophagus and cervix. However, there have been no reports on the interaction of select risk factors and p53 codon 72 polymorphisms in gastric cancer susceptibility. 155 gastric cancer cases and 134 cancer-free controls were enrolled at the Memorial Sloan Kettering Cancer Center (MSKCC) from November 1992 to November 1994. The crude odds ratio (OR1) associated with the (Pro/Pro) polymorphism and the risk of gastric cancer was 1.27 (0.70-2.33). Adjusting for age, sex, race and education (OR2) and further adjusting for BMI, calories, sodium, smoking, vitamin C, fiber, alcohol, fat, and H. pylori status (OR3) did not yield significant results. Significant joint effects were associated with high fat consumption (OR1=2.61 (95% CI:1.13-6.06); OR2=2.85 (95% CI:1.14-7.15) for total cancers and for proximal tumors (OR1=2.56 (95%CI:1.00-6.54)). The low vitamin C intake/high-risk polymorphism group (Pro/Pro) had an OR1 of 4.82 (95% CI: 1.72-13.45) and the OR2 was 6.19 (95% CI: 2.08-18.40) for distal tumors. The point estimates were increased for interaction odds ratios but not statistically significant (OR1=4.25 (95% CI: 0.66-27.50); OR2=4.73 (95% CI: 0.67-33.43); OR3=5.55 (95% CI: 0.66-46.47)). Further studies specifically looking at proximal and distal tumors are required to confirm any potential interaction between the p53 codon 72 polymorphisms and environmental risk, in particular low dietary vitamin C and high fat consumption.

p53 polymorphisms associated with mutations in and loss of heterozygosity of the p53 gene in male oral squamous cell carcinomas in Taiwan

The present study was designed to examine whether different p53 haplotypes of exon 4–intron 3–intron 6 affect the frequency of mutations and loss of heterozygosity (LOH) of the p53 gene in male oral squamous cell carcinomas (OSCCs) in Taiwan. We found that individuals without two Pro-W-G alleles had significantly higher frequency of p53 mutations than those with two Pro-W-G alleles (odds ratio (OR)=1.98; 95% confidence interval (CI), 1.10–3.56). Out of the 172 p53 gene exon 4 informative male OSCCs, 72 (41.9%) showed LOH. Among these 72 OSCCs with LOH, the frequency of Pro allele loss was 73.6% (53/72). It is notable that alcohol drinking increased the frequency of Arg allele loss (OR=10.56; 95% CI, 1.23–234.94) in OSCCs from patients who both smoked cigarettes and chewed areca quid (AQ). The frequency of LOH of p53 was not different between p53-mutated OSCCs and p53-normal OSCCs. Thus, the present study revealed that (a) the Arg allele is associated with p53 mutations, (b) the Pro allele is preferentially lost in OSCCs associated with cigarette smoking and AQ chewing, while the frequency of Arg allele loss is increased with alcohol drinking, and (c) haploinsufficiency of p53 is in itself likely to contribute to tumour progression in Taiwanese OSCCs.

Role of p53 codon 72 polymorphism in the risk of development of distal gastric cancer

OBJECTIVE

Mutations in the codon 72 of exon 4 in the p53 gene have been associated with higher risk in the development of several types of cancer. This polymorphism occurs with two alleles encoding either arginine (CGC) or proline (CCC). The aim of this study was to assess the role of the codon 72 polymorphism of p53 in the risk for the development of distal gastric cancer (GC) in a Mexican population.

MATERIAL AND METHODS

We studied 247 patients who were enrolled at the Servicio de Gastroenterologia, Hospital Universitario "Dr. José Eleuterio González" Universidad Autónoma de Nuevo León. The study group included 65 distal GC cases [mean age, 58.2 (22-84), median = 60, F:M = 0.6] and 182 patients without evidence of GC [mean age 53.9 (18-89), median = 53, F:M = 1.07) as the control group. The polymorphism in the codon 72 of the p53 gene was determined by PCR-RFLP in all the patients.

RESULTS

As expected, the majority of GC patients were old male. We found a previously unknown association of the Arg/Arg genotype and distal GC (OR: 1.96, 95% confidence interval [CI] = 1.06-3.61, p =0.03). Because of age and gender differences, cases and controls were matched in those two variables and the association of Arg/Arg genotype with distal GC persisted (OR: 2.29, 95% CI = 1.22-4.32, p = 0.01). When cases and controls were matched by age, gender, H. pylori positivity and excluding patients with atrophic gastritis and/or intestinal metaplasia (n=97) the association was stronger (OR = 2.37, 95% CI = 1.18-4.77, p = 0.01).

CONCLUSIONS

The results of this study suggest that the carriage of the Arg/Arg genotype could be associated with the development of distal GC in this Mexican population.

Prognostic value of TP53 codon 72 polymorphism in advanced gastric adenocarcinoma

PURPOSE

A common polymorphism of the tumor suppressor gene TP53 at codon 72 has been associated with human cancer susceptibility. The prognostic role of the polymorphism was assessed in 102 patients with advanced gastric adenocarcinoma.

EXPERIMENTAL DESIGN

We followed up 102 consecutive Caucasian patients with advanced gastric adenocarcinoma for >5 years and determined the status of the TP53 codon 72 polymorphism in DNA samples extracted from archived gastric tissues.

RESULTS

The frequency of the arginine homozygous allele was positively correlated to patient age at baseline (P = 0.002). However, the age-related increase in the percentage of codon 72 arginine p53 was not correlated to the prognosis for gastric cancer patients. Multivariable analysis in patients who had surgery showed that baseline age may be inversely associated with patient survival (odds ratio, 1.1; 95% confidence interval, 1.0-1.2; P = 0.02). Furthermore, alcohol consumption may be associated with reduced survival (P = 0.06).

CONCLUSIONS

These findings indicate that codon 72 arginine p53 may not be associated with a prolonged survival in patients with advanced gastric adenocarcinoma, but further study is needed to assess whether this polymorphism is associated with a late onset or slow progress of early gastric adenocarcinoma.

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Retention of the arginine allele in codon 72 of the p53 gene correlates with poor apoptosis in head and neck cancer

The allele constitution at codon 72 of the p53 gene (CGC-arginine or CCC-proline) plays a major role in inducing apoptosis in p53 mutant cells. To verify this, we determined GC-status, p53-mutations, and p53-loss of heterozygosity (LOH) in a group of 54 squamous cell carcinomas of the head and neck (SCCHN). A novel approach, using a one-step real-time PCR analysis with fluorescent hybridization probes, was applied to detect the GC status in tumors and corresponding blood samples. p53 mutations in exons 4 to 8 were detected by PCR-SSCP-sequencing analysis. Apoptosis was determined immunohistochemically using antibodies against Fas, FasL, p53, Bcl2, and terminal deoxy-transferase-mediated dUTP nick end labeling (TUNEL) staining. The overall frequency of p53-LOH in SCCHN was 45.2%. In cases of LOH, there was a preferential loss of the proline allele, which was associated with an up-regulation of Bcl2 and lack of co-expression of Fas/FasL and, thus, impaired apoptosis (P < 0.001). Apoptosis was not observed in tumors carrying the arginine allele. p53 mutations were detected in 29.6% of SCCHN and preferentially occurred at the arginine allele (P = 0.01). p53 alterations were more frequently observed in tumors of the oral cavity, oropharynx and hypopharynx, whereas they were rare in larynx carcinomas (P = 0.07). The p53-LOH status was not found to be significantly correlated with sex, age, TNM-status, or tumor grading. We conclude that apoptosis is correlated with the allelic status of codon 72 in SCCHN. Homozygous proline 72 appears to be an important regulator of apoptosis via the Fas/FasL pathway in SCCHN.

Locus-specific genetic diversity between human populations: an analysis of the literature

The debate over classification of the human species according to racial or continental lines has involved reports on genetic differences in allele frequencies of a number of loci with important biomedical functions. Such differences are in contrast with the fact that, for human beings, intrapopulation genetic diversity is larger than that seen between populations. In an attempt to address the hypothesis that certain genes show high interpopulation diversity due to selective pressure, the literature was surveyed to quantify such diversity using Wrights Fst statistic. The gene-specific Fst values were then compared to pairwise population values of Fst taken over a large number of genes, which presumably reflect mostly neutral mechanisms of genetic diversity such as drift. The results showed that the majority of pairwise population values of Fst for over 30 genes of biomedical significance were either below or within the expected limits of Fst based on published values. These results do not support the idea that positive or diversifying natural selection plays an important role in increasing genetic diversity, even in genes that might be expected to be subject to selection pressure. Balancing selection, whereby the degree of genetic diversity is actually lower than that expected, appears to occur more frequently for these genes. The fact that allele frequency differences between populations might be "statistically significant" does not therefore necessarily imply a degree of genetic diversity greater than would be expected due to nonselective mechanisms.

The p53 codon 72 polymorphism in Thai nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is a serious cancer in Thailand. To address on the genetic risk factor for NPC, we investigated association between the p53 codon 72 polymorphism (Pro/Arg) and NPC susceptibility in the Thai. The genotype frequency of this polymorphism in 102 NPC patients and 148 age-matched healthy controls was determined by using a PCR-RFLP assay. No statistically significant difference in the overall genotype frequencies or allele frequencies between cases and controls was observed. Among NPC patients, no statistical significant difference in p53 genotype frequencies between sex, histological types and clinical stages was observed. When cases and controls were categorized into 3 groups of age, >40, >45 and >50 years, the frequencies of p53 genotype in the cases were significantly different from those of the controls (P<0.05). The p53 Pro homozygotes with age of >40 years had twofold to threefold higher risk to develop NPC and the risk was increased with age (Odds Ratio (OR) increased from 2.01 to 2.63 by age >40 to >50 years). Individuals of age >40, >45 and >50 years with an Arg/Arg genotype and of age >45 and >50 years with combined Arg/Arg or Arg/Pro genotype had lower risk to develop NPC than those with Pro/Pro genotype (P<0.05). Collectively, we suggest that the p53 gene polymorphism may associate with NPC susceptibility in Thai population, particularly the Pro/Pro genotype carriers with age of >40 years. The detection of this p53 polymorphism may be a useful tool for screening of early stage and diagnosis of NPC.

TP53 and gastric carcinoma: a review

In this article, we survey the major p53 (TP53) alterations identified in gastric carcinomas and their precursors. These include p53 expression, mutations, and loss of heterozygosity (LOH). Not only are the various abnormalities summarized, but in addition there is a survey of the literature with respect to the impact of these changes on patient prognosis and treatment response. The majority of published studies involve the immunohistochemical detection of the protein. These use different antibodies, different detection techniques, and different methods of interpretation. Therefore not surprisingly, the results of many of the studies are contradictory with one another. Overall, however, it appears that p53 alterations occur early in the development of gastric carcinoma, being present even in the nonneoplastic mucosa and they increase in frequency as one progresses along the pathway of gastric carcinoma development. p53 immunoreactivity is seen in 17%-90.7% of invasive gastric carcinomas. p53 alterations occur much more commonly in proximal lesions than in distal ones, suggesting that the molecular events leading to the development of gastric carcinoma may be very different in proximal vs. distal tumors. p53 mutations occur in 0%-77% of gastric carcinomas. The mutations are distributed widely across the gene from exons 4-11 with hot spots of mutation at codons 175, 248, 273, 282, 245, and 213. G:C>A:T transitions at CpG sites are the commonest type of mutation. At least 60% of carcinomas with mutations also exhibit p53 LOH.

Differentially expressed genes in gastric tumors identified by cDNA array

Using cDNA fragments from the FAPESP/lICR Cancer Genome Project, we constructed a cDNA array having 4512 elements and determined gene expression in six normal and six tumor gastric tissues. Using t-statistics, we identified 80 cDNAs whose expression in normal and tumor samples differed more than 3.5 sample standard deviations. Using Self-Organizing Map, the expression profile of these cDNAs allowed perfect separation of malignant and non-malignant samples. Using the supervised learning procedure Support Vector Machine, we identified trios of cDNAs that could be used to classify samples as normal or tumor, based on single-array analysis. Finally, we identified genes with altered linear correlation when their expression in normal and tumor samples were compared. Further investigation concerning the function of these genes could contribute to the understanding of gastric carcinogenesis and may prove useful in molecular diagnostics.

p53 Codon 72 polymorphism and urothelial cancer risk

The p53 tumor suppressor gene is often mutated in various human cancers. Recently, the p53 codon 72 polymorphism has been extensively studied to determine the risk factors responsible for cancer formation. We investigated the genotype distribution of the p53 codon 72 polymorphism in 112 male urothelial cancer cases and 175 male unrelated non-cancer controls. The allelic frequencies in Japanese non-cancer controls were 0.58 (Arg) and 0.42 (Pro). There was no significant difference in the three genotype frequencies (Arg/Arg, Arg/Pro, Pro/Pro) of the p53 codon 72 between the urothelial cancer cases and the controls. However, stratifying by smoking status, we found that the frequency of the Pro/Pro genotype for smokers was significantly more than that for never-smokers (odds ratio (OR)=2.28, 95% confidence interval (95%CI)=1.12-4.66). Furthermore, we divided smoking status (pack-years) into quartiles (<20, 20-40, 40-60, >60). OR (Pro/Pro vs. Arg/Arg) for the lighter smokers (<20 pack-years) was higher than in other groups (OR=6.83). Our results suggest that the Pro/Pro genotype of the p53 codon 72 polymorphism increases the risk of urothelial cancer in smokers.

p53 Codon 72 polymorphism in gastric cancer susceptibility in patients with Helicobacter pylori-associated chronic gastritis

p53 codon 72, which produces variant proteins with an arginine (Arg) or proline (Pro), has been reported to be associated with cancers of the lung, esophagus and cervix. However, there have been no reports on the p53 codon 72 polymorphism in gastric cancer susceptibility in patients with Helicobacter pylori-associated chronic gastritis (H. pylori-CG). We, therefore, examined the polymorphism in 117 gastric cancer patients (72 intestinal type and 45 diffuse type) with H. pylori-CG and 116 H. pylori-CG patients without gastric cancer as controls. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis was performed to analyze the p53 codon 72 polymorphism. The crude genotypic frequencies in the gastric cancer patients were similar to those of the controls. However, when gastric cancers were classified by histologic subtype, the Pro/Pro was more frequent in the patients with diffuse type gastric cancer than in the controls (22.2% of cases vs. 12.1% of controls). The Pro/Pro genotype was associated with a 2.98-fold higher risk of diffuse-type cancer compared to the Arg/Arg genotype (95% confidence interval [CI] 1.07-8.32, p = 0.038). These results suggest that the Pro/Pro genotype at p53 codon 72 contributes to susceptibility for diffuse-type gastric cancer in patients with H. pylori-CG. The p53 codon 72 polymorphism may serve as the genetic marker for the risk assessment of the diffuse-type gastric cancer development in patients with H. pylori-CG.

Expression of p53 and its homologues in primary and recurrent squamous cell carcinomas of the head and neck

The tumour-suppressor protein p53 belongs to a family that includes 2 structurally related proteins, p63 and p73. Because of their structural homology, it has been hypothesized that both homologues serve as "spare mechanisms" in p53 mutations to regulate the cell cycle by inducing apoptosis. We investigated the mutational and protein expression status of p53 in correlation to its homologues, p73 and p63, in primary and recurrent squamous cell carcinomas of the head and neck (HNSCC) and corresponding nonneoplastic mucosa. Expression and mutation of p53 and its homologues p63 (including the 2 major isotypes TAp63 and DeltaNp63) and p73 was examined by direct DNA sequencing and immunohistochemistry in 29 primary and 39 recurrent (secondary) HNSCCs after microdissection. Our results were correlated with pathohistologic stage and grade. p53 mutations were detected in 32/68 (47%) carcinomas of 17 patients, with a discordant mutation pattern of primary and consecutive tumours in all cases. Positive immunostaining for p63 was found in 55/68 (81%) carcinomas of 29 patients. Immunohistochemistry revealed p73 protein expression in 32/68 (47%) tumours. In normal mucosa, p63 and p73 were expressed in 40/68 (59%) and 12/68 (18%) cases, respectively. We failed to detect specific mutations of p73 or p63 in primary and recurrent carcinoma of the head and neck. p73 and p63 were rarely mutated in HNSCC, but both were expressed in a subset of tumours. The lack of correlation between p73/p63 and p53 protein expression suggests that neither p73 nor p63 can replace p53 when it is mutated.

Association of the -160 C --> a promoter polymorphism of E-cadherin gene with gastric carcinoma risk

BACKGROUND

A -160 C --> A polymorphism in the promoter region of E-cadherin has been shown to decrease gene transcription. This allelic variation might be a potential genetic marker for identifying individuals at risk for cancer. There remains no report regarding the polymorphism of E-cadherin in gastric carcinoma (GC).

METHODS

A hospital-based case-control study, including 201 GC cases and 196 unaffected controls, was performed. DNA from peripheral blood samples was examined by polymerase chain reaction-restriction fragment length polymorphism. Logistic regression analyses were used to compute odds ratio (OR) and 95% confidence interval (CI) after adjusted for Helicobacter pylori infection, smoking, and other relevant factors.

RESULTS

In 196 healthy Taiwanese, the distribution of genotype C/C was 42.3%, C/A was 48.0%, and A/A was 9.7%. The frequency of variant A/A genotype in GC case (4 of 201, 2%) was significantly lower than that of controls (19 of 196, 9.7%) (P < 0.005), conferring a 5-fold decrease in the risk of GC (OR, 0.20; 95% CI, 0.06-0.56) compared with the C/C genotype. Stratification of the GC cases according to their location (cardia and noncardia), histology (intestinal and diffuse), tumor stage (early and advanced), and lymph node metastasis (positive and negative) failed to reveal any heterogeneity with respect to E-cadherin genotype.

CONCLUSIONS

The authors' data suggest that individuals with E-cadherin -160 A/A genotype have a decreased risk of GC. Further work is mandatory to clarify the functional relevance of the A allele in vivo and to confirm the inverse association of the A/A genotype with GC in large epidemiologic studies.

Prognostic significance of the proline form of p53 codon 72 polymorphism in nasopharyngeal carcinoma

OBJECTIVES/ HYPOTHESIS

An important tumor suppressor gene, p53, plays a role in the regulation of cell progression and prevention of carcinogenesis. Mutated p53 is related to cell progression and malignancy. We aimed to evaluate the association between nasopharyngeal carcinoma and p53 polymorphism.

STUDY DESIGN

Case control study.

METHODS

All individuals were divided into two groups: nasopharyngeal carcinoma (n = 50) and non-nasopharyngeal carcinoma groups (n = 59). Their p53 codon 72 polymorphisms (arginine [Arg] homozygotes, heterozygotes, proline [Pro] homozygotes) were detected by polymerase chain reaction. Associations between nasopharyngeal carcinoma and p53 polymorphism were evaluated.

RESULTS

Distributions of various p53 polymorphisms significantly differed between the two groups. We noted a dominant presentation of Pro homozygotes in the nasopharyngeal carcinoma population over that in the non-nasopharyngeal carcinoma population. Proportions of Pro homozygotes and heterozygotes and Arg homozygotes were 32%, 28%, and 40% in the nasopharyngeal carcinoma population and were 13.5%, 44.1%, and 42.4% in the non-nasopharyngeal carcinoma population, respectively.

CONCLUSIONS

An association exists between nasopharyngeal carcinoma and p53 codon 72 polymorphism. The p53 Pro homozygotes are to a higher risk of development of nasopharyngeal carcinoma.

Expression of the p53 homologues p63 and p73 in multiple simultaneous gastric cancer

The tumour-suppressor protein p53 has recently been shown to belong to a family that includes two structurally related proteins, p63 and p73. This study investigated the status of p53 and its two homologues in multiple simultaneous gastric carcinomas. Expression and mutation of p53, p73 and p63 including the two major isotypes TAp63 and black triangleNp63, were examined by direct DNA-sequencing, in situ hybridization, western blotting and immunohistochemistry in 68 gastric carcinomas of 32 patients. The results obtained were correlated with pathohistological stage (according to UICC(16)) and several other histopathological factors and finally with patient survival. p53 mutations were detected in 23/68 carcinomas (34%) from 18 patients with a discordant mutation pattern. Independently of p53 mutation status, p73 transcripts and protein expression were found in 33/68 carcinomas from 24 patients. p63 positivity was found in 21 patients; 25 out of 68 tumours expressed p63. The number of cells containing p63 and their distribution depend on the degree of tumour differentiation. High grade carcinomas of the diffuse type exhibited a significantly higher p63 expression. In intestinal metaplasia and atrophic gastritis, an increase of TAp63 and black triangleNp63 staining was also observed. Specific mutations of p73 or p63 causing amino acid substitutions were not identified. Neither p53, p73 nor p63 were related to prognosis. p73 and p63 have rarely been found to be mutated in gastric carcinomas, but both proteins were expressed in only a subset of tumours. The status of these p53 homologues was discordant in all patients with multiple simultaneous gastric carcinomas. The increased expression of p63 (TAp63 and black triangleNp63) in less well differentiated gastric carcinomas may indicate that p63 can act to promote neoplastic growth in the gastric epithelium.