Analysis of a germ line polymorphism of the p53 gene in lung cancer patients; discrete results with smoking history

The cell cycle regulatory gene polymorphisms TP53 (rs1042522) and MDM2 (rs2279744) in lung cancer: a meta-analysis

Lung cancer is one of the most common types of cancer in the world. Although the mechanism of lung cancer is still unknown, a large number of studies have found a link between gene polymorphisms and the risk of lung cancer. The tumor suppressor p53 plays a crucial role in maintaining genomic stability and tumor prevention. MDM2 is a critical regulator of the p53 protein. Despite the importance of p53 pathway in cancer, data on the contribution of SNPs of TP53 (rs1042522) and MDM2 (rs2279744) to the development of lung cancer are very contradictory. A metaanalysis that collects quantitative data from individual studies and combines their results has the advantage of improving accuracy, providing reliable estimates, and resolving those issues in which studies on individual associations are not effective enough. The aim of this study was to determine whether the TP53 (rs1042522) and MDM2 (rs2279744) polymorphisms confer susceptibility to lung cancer. A meta-analysis was conducted on the associations between the TP53 (rs1042522) and MDM2 (rs2279744) polymorphisms and lung cancer. A total of 51 comparison studies including 25,366 patients and 25,239 controls were considered in this meta-analysis. The meta-analysis showed no association between lung cancer and MDM2 (rs2279744) under any model. A noteworthy association of TP53 (rs1042522) with susceptibility to lung cancer in overall pooled subjects was observed under three different models (allele contrast, homozygote contrast (additive) and dominant). Stratification by ethnicity indicated an association between the TP53 (rs1042522) and lung cancer in Asians and Caucasians. This meta-analysis demonstrates that the TP53 (rs1042522), but not MDM2 (rs2279744) polymorphism may confer susceptibility to lung cancer.

Association of TP53 Codon 72 Arg>Pro Polymorphism with Breast and Lung Cancer Risk in the South Asian Population: A Meta-Analysis

BACKGROUND

A transversion missense polymorphism of the TP53 tumor suppressor gene at the codon 72 codes proline instead of arginine causes an altered p53 protein expression and has been found to be associated with an elevated risk of various cancer; especially breast and lung cancer. As the previous case-control studies on the South Asian population have shown controversial results, we performed a meta-analysis to evaluate a precise estimation of the relationship between the TP53 Arg72Pro polymorphism with breast and lung cancer.

METHODS

A total of 12 related studies on the South Asian population have been included through comprehensive database searching. Six studies were selected for breast cancer meta-analysis involving 950 cases and 882 controls; the other six studies were for lung cancer meta-analysis including 975 cases and 1397 controls. The results have been determined by using the Review Manager (RevMan) 5.3. Additionally, the stability of our analysis was assessed by heterogeneity, publication bias analysis and sensitivity testing.

RESULTS

A significantly increased risk of breast cancer was found in Pro allele (Pro vs. Arg), co-dominant model 2 (Pro/Pro vs. Arg/Arg), dominant model (Pro/Pro + Arg/Pro vs. Arg/Arg). In case of lung cancer, significantly increased risk was found in the allele, co-dominant 1, co-dominant 2, co-dominant 3, dominant, and recessive models. No association with other genetic models with breast and lung cancer risk was found in the South Asian population.

CONCLUSIONS

Our results indicate that TP53 Arg72Pro polymorphism is a risk factor for the development of breast cancer and lung cancer in the South Asian population.

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.

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.

TP53 Mutations in Human Meningiomas

Overexpression of p53 has been reported to play a role in the development of neoplasms of the central nervous system. Meningiomas are generally benign intracranial tumors originating from the meninges. Overexpression of the p53 protein in meningiomas and an association with histological type and recurrence has been reported. Mutation of the TP53 gene leads to a more stable p53 protein in quantities high enough for detection by immunohistochemistry. In the search for these mutations the core domain of the TP53 gene of meningiomas has been analyzed. Only a very low incidence of mutations was reported. The apparent discordance between overexpression of p53 protein and TP53 gene mutations may be explained by mutations located outside the core domain. This issue was addressed in the present study. All 11 exons of 17 meningiomas were analyzed for DNA alterations by PCR single-strand conformation polymorphism (PCR-SS-CP) analysis with subsequent sequencing. PCR-SSCP analysis showed a various number of band shifts and nucleotide alterations, caused either by alterations in the flanking introns or common polymorphisms (codon 36 and 72). The allele frequencies of the polymorphisms found in this small population of tumors resemble the frequencies reported in the literature. In addition, three nucleotide changes located in introns 2, 3 and 7 were found in 11, 3 and 4, respectively, of 17 specimens. Based on this study and on reports by others we conclude that it is not very likely that TP53 mutations are involved in the etiology of meningiomas.

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.

Tumor suppressor miR-24 restrains gastric cancer progression by downregulating RegIV

BACKGROUND

microRNAs are small noncoding RNAs that modulate a variety of cellular processes by regulating multiple targets, which can promote or inhibit the development of malignant behaviors. Accumulating evidence suggests miR-24 plays important roles in human carcinogenesis. However, its precise biological role remains largely elusive. This study examined the role of miR-24 in gastric cancer (GC).

METHODS

The expression of miR-24 in GC tissues compared with matched non-tumor tissues and GC cells was detected by qRT-PCR. Synthetic short single or double stranded RNA oligonucleotides and lentiviral vectors were used to regulate miR-24 expression in GC cells to investigate its function in vitro and in vivo.

RESULTS

miR-24 was significantly downregulated in GC tissues compared with matched non-tumor tissues and was associated with tumor differentiation. Ectopic expression of miR-24 in SGC-7901 GC cells suppressed cell proliferation, migration and invasion in vitro as well as tumorigenicity in vivo by inducing cell cycle arrest in G0/G1 phase and promoting cell apoptosis. Furthermore, we identified RegIV as a target of miR-24 and demonstrated that miR-24 regulated RegIV expression via binding its 3' untranslated region.

CONCLUSIONS

miR-24 functions as a novel tumor suppressor in GC and the anti-oncogenic activity may involve its inhibition of the target gene RegIV. These findings suggest the possibility for miR-24 as a therapeutic target in GC.

Less common genotype variants of TP53 polymorphisms are associated with poor outcome in adult patients with adrenocortical carcinoma

CONTEXT

The Li-Fraumeni tumor syndrome is strongly associated with adrenocortical carcinoma (ACC) and is caused by germline mutations in TP53 in 70% of cases. Also, TP53 polymorphisms have been shown to influence both cancer risk and clinical outcome in several tumor entities. We, therefore, investigated TP53 polymorphisms in a cohort of adult patients with ACC.

OBJECTIVE

Evaluation of the role of TP53 polymorphisms in adult patients with ACC.

SUBJECTS AND METHODS

Peripheral blood for DNA extraction was collected from 72 ACC patients. Polymorphism analysis was carried out by amplification and sequencing of exons and adjacent intron sections of TP53. Results were correlated with clinical data and the distribution of the polymorphisms was compared with published Caucasian control groups.

RESULTS

Compared with control groups, genotype frequencies of analyzed TP53 polymorphisms among ACC patients were significantly different in three out of four polymorphisms: IVS2+38G>C (G/G, P=0.0248), IVS3ins16 (NoIns/NoIns, P<0.0001; NoIns/Ins, P<0.0001), and IVS6+62A>G (G/G, P<0.0001; G/A, P<0.0001). Overall, the survival of ACC patients, which harbored at least one of the less frequent genotype variants of four analyzed polymorphisms (n=23), was significantly inferior (median survival: 81.0 months in patients with the common homozygous genotypes vs 20.0 months in patients with the less frequent genotypes, HR 2.56, 95% CI 1.66-7.07; P=0.001). These results were confirmed by multivariable regression analysis (HR 2.84, 95% CI 1.52-7.17; P=0.037).

CONCLUSION

Some TP53 polymorphisms seem to influence overall survival in ACC patients. This effect was observed for a combination of polymorphic changes rather than for single polymorphisms.

Association of p53 Arg72Pro polymorphism with esophageal cancer: a meta-analysis based on 14 case-control studies

BACKGROUND

The p53 tumor suppressor gene Arg72Pro polymorphism has been associated with esophageal cancer. However, the results were not consistent. Herein, this meta-analysis was performed to estimate the association between p53 Arg72Pro polymorphism and esophageal cancer.

METHODS

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

RESULTS

The final meta-analysis included 14 published studies with 4184 esophageal cancer cases and 7308 controls. The results suggested that the variant genotype was associated with the esophageal cancer risk in additive model (Pro vs. Arg: OR=1.146, 95% CI: 1.016-1.293, p=0.027) and in recessive model (Pro/Pro vs. Arg/Arg+Arg/Pro: OR=1.258, 95% CI: 1.021-1.551, p=0.031). In the stratified analysis by ethnicity, the data suggested that the increased esophageal cancer risk associated with p53 Arg72Pro polymorphism was more evident in the Asian group. The symmetric funnel plot, the Egger's test (p>0.05) and the Begg's test (p>0.05) suggested the lack of publication bias.

CONCLUSION

This meta-analysis suggests that p53 codon 72 polymorphism contributes to esophageal cancer risk, especially in Asians. To validate this association, further studies with more participants worldwide are needed to examine association between this polymorphism and esophageal cancer.

P53 codon 72 Arg/Pro polymorphism and lung cancer risk in Asians: an updated meta-analysis

The polymorphism of p53 codon 72, a transversion of G to C (Arg to Pro), has been demonstrated to be associated with the risk for lung cancer. However, individual studies conducted in Asians have provided conflicting and inconclusive findings. Thus, we performed a meta-analysis by pooling all currently available case–control studies to estimate the effect of p53 codon 72 Arg/Pro polymorphism on the development of lung cancer. The pooled odds ratios (ORs) with the corresponding 95 % confidence intervals (95 %CIs) were calculated to assess this effect. A total of 14 individual studies involving 7,929 cases and 5,924 controls were included into this meta-analysis according to the inclusion criteria. The overall OR for the dominant genetic model indicated that the p53 codon 72 Arg/Pro variant was positively correlated with lung cancer risk (OR_{Arg/Pro + Pro/Pro vs. Arg/Arg} = 1.14, 95 %CI 1.07–1.23, P_OR < 0.001). Similar results were found in the stratified analysis of population-based studies. The histological types of lung cancer and smoking status seemed to exert no effect on the lung cancer risk. Sensitivity analysis confirmed the stability of the above findings. The updated meta-analysis suggests that the p53 codon 72 Arg/Pro polymorphism is a risk factor for lung cancer in the Asian population. However, the potential role of gene–environment interaction in lung cancer susceptibility needs further investigation in future studies with high quality.

The association between TP53 Arg72Pro polymorphism and lung cancer susceptibility: evidence from 30,038 subjects

BACKGROUND

The TP53 codon 72 polymorphism has been associated with the individual susceptibility to lung cancer. However, the association remains uncertain and varies with ethnicity, smoking status, cancer histology, and stage.

METHODS

We performed a meta-analysis to evaluate the relationship between TP53 Arg72Pro polymorphism and lung cancer susceptibility basing on 15,647 lung cancer patients and 14,391 controls from 36 published literatures. We also performed stratified analysis in populations of different ethnicities, smoking statuses, lung cancer stages, and histological types.

RESULTS

The analysis showed a significantly increased lung cancer susceptibility among Pro allele carriers (P < 0.001, odds ratio (OR) = 1.14, 95% confidence interval (CI) = 1.1-1.19), especially for smokers (P < 0.001, OR = 1.29, 95% CI = 1.12-1.47). Stratified analysis indicated that Pro72 elevates lung cancer susceptibility in Asians, while it has no effect on lung cancer risk of Caucasians. Moreover, Pro carriers present an increased risk of developing squamous cell carcinoma and adenocarcinoma, instead of large cell carcinoma and small cell carcinoma. Interestingly, patients with the Pro allele seemed to be diagnosed with lung cancer at the early stages (stage I-II, P = 0.008, OR = 1.2, 95% CI = 1.05-1.37).

CONCLUSIONS

Our results suggest that the Pro allele acts as a risk factor for development of lung cancer, especially for smokers and Asians.

Polymorphism Arg72Pro of p53 confers susceptibility to squamous cell carcinoma of lungs in a North Indian population

The causes of lung cancer might be many, but genetic variation in the genes of carcinogen-metabolizing enzymes, tumor suppressor proteins, and/or DNA-repairing enzymes can also play a significant role in lung cancer susceptibility. The tumor suppressor protein p53 functions to induce cell cycle arrest, DNA repair, or apoptosis. Polymorphism in its gene can, therefore, play a significant role in cancer susceptibility. Present report evaluated the association of polymorphism in exon 4 Arg72Pro (G>C) of the p53 gene with lung cancer susceptibility using 175 cancer cases and 202 controls from the North Indian population. Binary logistic regression analysis revealed that the Pro72Pro genotype was significantly associated with increasing risk for lung cancer in younger age patients (≤55 years) (adjusted odds ratio [OR]=2.72, 95% confidence intervals [95% CI] 0.99-7.85, p<0.05). Histological stratification of lung cancer revealed that the Pro72Pro genotype was associated with higher risk for squamous cell carcinoma (OR=3.05, 95% CI 1.07-8.87, p<0.05). Genetic variation Arg72Pro of the p53 gene may contribute to higher risk of SCC of lung in the North Indian population.

Association between XRCC1 ARG399GLN and P53 ARG72PRO polymorphisms and the risk of gastric and colorectal cancer in Turkish population

Gastric cancer is one of the most common cancers of the gastrointestinal system, and its overall five-year survival rate is still 15 % to 20 %, as it can mostly be diagnosed at an advanced stage. On the other hand, although colorectal cancer has a rather good prognosis, mortality is one half that of the incidence.As carcinogenesis is believed to involve reactive radicals that cause DNA adduct formation, impaired repair activity, and weakened tumour suppression, it would help to understand the role of the polymorphisms of nucleotide excision repair enzyme XRCC1 and of tumour suppressor gene p53 in gastric and colorectal cancers. Our study included 94 gastric cancer patients, 96 colorectal cancer patients, and 108 cancer-free individuals as control with the aim to see if there was an association between XRCC1 Arg399Gln and p53 Arg72Pro polymorphisms and cancer susceptibility. DNA was extracted from peripheral blood cells and genotypes were determined using the polymerase chain reaction-restriction fragment length polymorphism. Polymorphism p53 Arg72Pro was not associated with either gastric or colorectal carcinoma, while XRCC1 Arg399Gln was not associated with the increased risk of colorectal cancer. However, XRCC1 homozygous Gln allele at codon 399 was associated with 2.54 times higher risk of gastric cancer.

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.

Arg72Pro TP53 polymorphism and cancer susceptibility: a comprehensive meta-analysis of 302 case-control studies

Arg72Pro is a common polymorphism in TP53, showing differences in its biological functions. Case-control studies have been performed to elucidate the role of Arg72Pro in cancer, although the results are conflicting and heterogeneous. Here, we analyzed pooled data from case-control studies to determine the role of Arg72Pro in different cancer sites. We performed a systematic review and meta-analysis of 302 case-control studies that analyzed Arg72Pro in cancer susceptibility. Odds ratios were estimated for different tumor sites using distinct genetic models, and the heterogeneity between studies was explored using I(2) values and meta-regression. We adopted quality criteria to classify the studies. Subgroup analyses were done for tumor sites according to ethnicity, histological, and anatomical sites. Results indicated that Arg72Pro is associated with higher susceptibility to cancer in some tumor sites, mainly hepatocarcinoma. For some tumor sites, quality of studies was associated with the size of genetic association, mainly in cervical, head and neck, gastric, and lung cancer. However, study quality did not explain the observed heterogeneity substantially. Meta-regression showed that ethnicity, allelic frequency and genotyping method were responsible for a substantial part of the heterogeneity observed. Our results suggest ethnicity and histological and anatomical sites may modulate the penetrance of Arg72Pro in cancer susceptibility. This meta-analysis denotes the importance for more studies with good quality and that the covariates responsible for heterogeneity should be controlled to obtain a more conclusive response about the function of Arg72Pro in cancer.

TP53 R72P and MDM2 SNP309 polymorphisms and colorectal cancer risk: the Fukuoka Colorectal Cancer Study

OBJECTIVE

Tumor protein p53 gene and its negative regulator, murine double minute 2 homolog are important components for cell-cycle arrest and apoptosis. An arginine-to-proline substitution at codon 72 in the p53 gene is reported to decrease apoptotic potential, while a thymine-to-guanine polymorphism at nucleotide 309, named SNP309, of murine double minute 2 gene increases transcription of the gene. These two polymorphisms therefore may be of importance in colorectal carcinogenesis. The relation of these polymorphisms to colorectal cancer risk was addressed in the Fukuoka Colorectal Cancer Study.

METHODS

We genotyped the two polymorphisms in 685 incident cases of colorectal cancer and 778 community controls by the polymerase chain reaction-restriction fragment length polymorphism method. Statistical adjustment was made for sex and age.

RESULTS

The proline allele of p53 gene and the guanine allele of SNP309 were each associated with a small, statistically non-significant increase in the odds ratio of colorectal cancer; the adjusted odds ratio (95% confidence interval) for arginine/proline and proline/proline genotypes combined versus arginine/arginine genotype of p53 gene was 1.23 (0.99-1.52) and that for thymine/guanine and guanine/guanine genotypes combined versus thymine/thymine genotype of SNP309 was 1.27 (0.98-1.63). Individuals harboring the proline allele of p53 gene and the guanine allele of SNP309 showed an odds ratio of 1.67 (95% confidence interval, 1.11-2.51).

CONCLUSIONS

Codon 72 polymorphism of p53 and SNP309 in combination may confer an increased risk of colorectal cancer.

TP53 Arg72Pro polymorphism and colorectal cancer risk: a systematic review and meta-analysis

BACKGROUND

The TP53 rs1042522 polymorphism (c.215C>G, Arg72Pro) has been extensively investigated as a potential risk factor for colorectal cancer, but the results have thus far been inconclusive.

METHODS

We searched multiple electronic databases to identify studies investigating the association between the Arg72Pro polymorphism and colorectal cancer. Individual study odds ratios (OR) and their confidence intervals were estimated using allele-frequency, recessive, and dominant genetic models. Summary ORs where estimated using random effects models.

RESULTS

We identified 23 eligible case-control studies, investigating 6,514 cases and 9,334 controls. There was significant between-study heterogeneity for all genetic models. The control group in one of the studies was not in Hardy-Weinberg equilibrium; only three studies reported that genotyping was blinded to case/control status and five studies used tumor tissue for case genotyping. Overall, we did not identify any association between rs1042522 and colorectal cancer risk under an allele-frequency comparison (OR, 0.99; 95% confidence interval, 0.89-1.09). Likewise, no association was evident under dominant or recessive models. Studies using tumor tissue for case genotyping found a protective effect for the Pro allele, compared with studies using somatic DNA (P(interaction) = 0.03). Results were also inconsistent between different genotyping methods (P(interaction) = 0.03).

CONCLUSION

We did not identify an association between TP53 rs1042522 and colorectal cancer. Published results seem to be driven by technical artifacts rather than true biological effects.

IMPACT

Future genetic association studies should use more rigorous genotyping methods and avoid the use of tumor tissue as a source of DNA to prevent genotype misclassification due to loss of heterozygosity.

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.

Effect of MDM2 SNP309 and p53 codon 72 polymorphisms on lung cancer risk and survival among non-smoking Chinese women in Singapore

Background

Single nucleotide polymorphism (SNP) 309 resulting in a T or G allele in the promoter of MDM2, the negative regulator of p53, has been suggested to affect cancer predisposition and age of onset, primarily in females. However, findings have been inconsistent in various cancers, and ethnicity appears to be a critical factor influencing the effects of the SNP on cancer risk. An increasing trend has been observed in the prevalence of lung cancers in non-smokers, especially females, though the underlying genetic basis is unclear.

Methods

We therefore examined the role of the SNPs in the p53 pathway (p53 codon 72 and MDM2 SNP309) on lung cancer risk and prognosis of a life-time non-smoking female Chinese population, in a hospital-based case-control study of 123 cases and 159 age-matched controls, by PCR analysis.

Results

Our findings reveal that the risk of lung cancer among individuals with the MDM2 SNP309 TT genotype was 2.1 (95% CI 1.01-4.36) relative to the GG genotype, contrary to initial expectations that the GG genotype with elevated MDM2 levels will increase cancer risk. Those who had this genotype in combination with the p53 Pro allele had a risk of 2.5 (95% CI 1.2-5.0). There was however no effect of either polymorphism on age at diagnosis of lung cancer or on overall survival.

Conclusions

The results thus demonstrate that the MDM2 SNP309 TT rather than the GG genotype is associated with increased risk of lung cancer in this population, suggesting that other mechanisms independent of increased MDM2 levels can influence cancer susceptibility.

Development and progression of colorectal neoplasia

A variety of genetic and molecular alterations underlie the development and progression of colorectal neoplasia (CRN). Most of these cancers arise sporadically due to multiple somatic mutations and genetic instability. Genetic instability includes chromosomal instability (CIN) and microsatellite instability (MSI), which is observed in most hereditary non-polyposis colon cancers (HNPCCs) and accounts for a small proportion of sporadic CRN. Although many biomarkers have been used in the diagnosis and prediction of the clinical outcomes of CRNs, no single marker has established value. New markers and genes associated with the development and progression of CRNs are being discovered at an accelerated rate. CRN is a heterogeneous disease, especially with respect to the anatomic location of the tumor, race/ethnicity differences, and genetic and dietary interactions that influence its development and progression and act as confounders. Hence, efforts related to biomarker discovery should focus on identification of individual differences based on tumor stage, tumor anatomic location, and race/ethnicity; on the discovery of molecules (genes, mRNA transcripts, and proteins) relevant to these differences; and on development of therapeutic approaches to target these molecules in developing personalized medicine. Such strategies have the potential of reducing the personal and socio-economic burden of CRNs. Here, we systematically review molecular and other pathologic features as they relate to the development, early detection, diagnosis, prognosis, progression, and prevention of CRNs, especially colorectal cancers (CRCs).

TP53 Arg72Pro polymorphism and lung cancer risk: a meta-analysis

No clear consensus has been reached on the TP53 Arg72Pro polymorphism (G12139C) and lung cancer risk. Thus, a meta-analysis was conducted to summarize the possible association. There was no statistical association between 12139C (Pro allele) and lung cancer risk in Caucasians compared with 12139G allele. However, the association was observed in all subjects (9,387 patients and 9,922 controls, p=0.04, OR=1.08, 95% CI 1.00-1.17), as well as in Asians (p=0.0004, OR=1.14, 95% CI 1.06-1.22). The association was also found in Asians under recessive genetic model (p<0.00001, OR=1.37, 95% CI 1.20-1.57) and homozygote comparison (CC vs. GG) (p<0.0001, OR=1.34, 95% CI 1.16-1.56). 12139C allele might increase the lung adenocarcinoma risk compared with 12139G allele (p=0.01, OR=1.11, 95% CI 1.02-1.21), and the effect was also found under recessive genetic model (p=0.003, OR=1.28, 95% CI 1.09-1.50) and homozygote comparison (CC vs. GG) (p=0.007, OR=1.28, 95% CI 1.07-1.52). There was an elevated association between the 12139C and the stage I lung cancer under dominant genetic model (p=0.04, OR=1.48, 95% CI 1.02-2.16), but no association was observed in other stages. No association of smoking was found between 12139C allele and lung cancer under recessive genetic model. Our result indicated that 12139C might increase the risk of lung cancer under recessive genetic model in adenocarcinoma, in Asians, and in lung cancer stage I. More studies stratified for lung cancer stage-genotyping interaction should be performed to clarify the role of TP53 Arg72Pro polymorphism in the development of lung cancer.

Impact of interaction of polymorphic forms of p53 codon 72 and N-acetylation gene (NAT2) on the risk of lung cancer in the North Indian population

The interaction of genetic and environmental factors can determine individual susceptibility to various cancers. We studied the influence of NAT2 and codon 72 p53 polymorphisms on 151 patients with lung cancer and an equal number of matched population controls. Polymorphisms of NAT2 and p53 were determined by PCR-RFLP techniques. The results were analyzed using logistic regression analysis. A statistically significant relationship between NAT2*5 and NAT2*6 alleles and lung cancer risk was observed. In addition, the population with slow acetylator alleles for NAT2*5 and NAT2*6 had a significantly higher risk of lung cancer compared with rapid acetylator alleles both in smokers and nonsmokers. The combined genotype of heterozygous arginine (Arg)/proline (Pro), Pro/Pro, and slow acetylator alleles of NAT2*5 and NAT2*6 showed higher, although not significant, risk of lung cancer compared with Arg/Arg and rapid acetylator alleles of NAT2*5 and NAT2*6. In conclusion, these findings suggest that the influence of NAT2 genotype, alone or in combination with p53 genotype, may confer increased susceptibility to lung cancer.

P53 polymorphism and lung cancer susceptibility: a pooled analysis of 32 case-control studies

To explore the real association between p53 codon 72 polymorphism and lung cancer risk, a pooled analysis of 32 case-control studies involving 19,255 subjects was conducted. When all 32 studies were pooled into the analysis, significantly elevated lung cancer risks were associated with variant genotypes in all genetic models (for Pro/Arg vs. Arg/Arg: OR 1.21, 95% CI 1.01-1.23; for Pro/Pro vs. Arg/Arg: OR 1.20, 95% CI 1.03-1.39; for Pro/Pro + Pro/Arg vs. Arg/Arg: OR 1.14, 95% CI 1.03-1.25; for Pro/Pro vs. Arg/Arg + Pro/Arg: OR 1.06, 95% CI 1.01-1.12). In the subgroup analysis by ethnicity, histological type, or smoking status, significantly increased risks were found in subgroups such as Asians, Caucasians, lung adenocarcinoma patients, or smokers, respectively. In conclusion, our results suggest that the Pro allele at p53 codon 72 is emerging as a low-penetrance susceptibility allele for lung cancer development.

The risk of gastric cancer in patients with duodenal and gastric ulcer: research progresses and clinical implications

INTRODUCTION

Although controversial, clinicians generally consider patients who present with gastric ulcer to have an increased risk of gastric cancer, while the risk for patients with duodenal ulcer is reduced in comparison with that of the general population. Infection with Helicobacter pylori and the use of non-steroidal anti-inflammatory drugs (NSAIDs) are the major causes for peptic ulcers, but their roles in relation to the risk of gastric cancer in patients with peptic ulcer may be different.

METHODS AND RESULTS

This article reviewed existing literature to assess our understanding of the risk of gastric cancer in patients with gastric and duodenal ulcers more than 25 years after the discovery of H. pylori and also examined whether gastric ulcers induced by NSAID carry a lower risk of gastric cancer as compared to those induced by H. pylori infection or other causes.

A meta-analysis of TP53 codon 72 polymorphism and lung cancer risk: evidence from 15,857 subjects

The genetic polymorphism of TP53 codon 72 is thought to have significant effect on lung cancer risk, but the results are inconsistent. In this meta-analysis, we assessed 23 published studies involving 15,857 subjects of the association between TP53 codon 72 polymorphism and risk of lung cancer. For the homozygote Pro/Pro and Pro allele carriers (Pro/Pro+Pro/Arg), the ORs for all studies combined (7495 cases and 8362 controls) were 1.221 (95% CI=1.046-1.425; P=0.021 for heterogeneity) and 1.148 (95% CI=1.040-1.266; P=0.008 for heterogeneity). In the stratified analysis by ethnicity, significantly increased risks were found in Asians (3254 cases and 3350 controls) for both the homozygote Pro/Pro (OR=1.395; 95% CI=1.206-1.613; P=0.806 for heterogeneity) and the Pro allele carriers (OR=1.109; 95% CI=1.000-1.228; P=0.458 for heterogeneity). In Caucasians (3359 cases and 3953 controls), significantly elevated risk was associated with Pro allele carriers (OR=1.180; 95% CI=1.029-1.353; P=0.073 for heterogeneity). In the subgroup analyses by pathological type, the ORs for the homozygote Pro/Pro and Pro allele carriers were 1.289 (95% CI=1.027-1.618; P=0.096 for heterogeneity) and 1.168 (95% CI=1.062-1.284; P=0.231 for heterogeneity) for lung adenocarcinoma (2724 cases and 6591 controls). When stratified by smoking status, the pooled OR was 1.440 (95% CI=1.078-1.923; P=0.042 for heterogeneity) for the Pro allele carriers among smokers (1480 cases and 1414 controls). Although some statistical bias could not be eliminated, this meta-analysis suggests that the Pro allele is a low-penetrant risk factor for developing lung cancer. Additionally, we found that this phenomenon was more prominent in subgroups such as in Asians and Caucasians, in lung adenocarcinoma, or in smokers.

Association of the TP53 codon 72 polymorphism with colorectal cancer in a Chinese population

A TP53 gene polymorphism, resulting in an arginine (R) to proline (P) at codon 72 (TP53 R72P), has been associated with the susceptibility to various cancers. To better understand the role of this polymorphism in colorectal cancer etiology, we examined the association between TP53 R72P and colorectal cancer risk in 345 patients with colorectal cancer and 670 controls in a Chinese population. We observed that subjects with RP and PP genotypes had a 1.60-fold and a 2.37-fold increased risk for colorectal cancer, respectively. The 72P allele conferred a more pronounced increase in colorectal cancer risk among alcohol consumers (heterozygotes: OR = 3.01; homozygotes: OR = 4.71). The TP53 R72P polymorphism was not linked to tumor location, histologic grade, lymph node metastases, Dukes stage, p53 positivity, or age at diagnosis, but to tumor size. We conclude that the TP53 R72P polymorphism may contribute to the etiology of colorectal cancer in the Chinese population, particularly among alcohol consumers.

P53 gene codon 72 polymorphism and risk of esophageal squamous cell carcinoma: a case/control study in a Chinese population

The aims of this study were to investigate whether p53 gene codon 72 polymorphism was a biomarker associated with esophageal squamous cell carcinoma (ESCC) and its relationship with smoking status in China. The p53 genotypes were determined by polymerase chain reaction-restriction fragment length polymorphism among 673 patients with ESCC and 694 healthy controls. The association between p53 genotypes and risk of developing ESCC was estimated by odds ratios (OR) and their 95% confidence intervals (CIs) computed by logistic regression. Compared with Arg/Arg homozygotes, Pro/Pro homozygotes had a nearly twofold increased risk (adjusted OR, 1.83; 95% CI, 1.35-2.48). For the Pro/Arg heterozygotes, there was no evident increased risk (adjusted OR, 1.01, 95% CI, 0.78-1.30). Furthermore, the risk associated with the Pro/Pro variant genotype was more pronounced in younger patients at diagnosis (= 45 years) (OR, 7.4; 95% CI, 1.44-37.89, P = 0.02), in women (OR, 3.15; 95% CI, 1.52-4.53, P = 0.02) and in non-smokers (OR, 2.49; 95% CI, 1.58-3.94) and light smokers (OR, 2.13; 95% CI, 1.15-3.93). But tests for homogeneity between smoking-related OR showed no significant differences (P = 0.4). The p53 gene codon 72 Pro/Pro genotype was significantly associated with the increased risk of ESCC in a Chinese mainland population and may be an independent factor in susceptibility to ESCC. The association was especially noteworthy in women and in younger patients.

Polymorphisms of cytochrome P450 1A1, glutathione S-transferase class mu, and tumour protein p53 genes and the risk of developing gallbladder cancer in Japanese

OBJECTIVES

To examine the relationship between genetic polymorphisms of cytochrome P450 1A1 (CYP1A1), glutathione S-transferase class mu (GSTM1), and tumour protein p53 (TP53) genes, and gallbladder cancer (GBC) risk, a case-control study was conducted.

DESIGN AND METHODS

Genotypes of CYP1A1 T3801C, CYP1A1 Ile462Val, GSTM1, and TP53 Arg72Pro were determined in 54 cases of GBC and 178 controls.

RESULTS

The age-adjusted odds ratios (ORs) for the Ile/Val genotype of CYP1A1 Ile462Val polymorphism in women and the Arg/Pro genotype of TP53 Arg72Pro polymorphism in men were observed to be 2.70 (95% CI: 1.14-6.40) and 4.32 (95% CI: 1.08-17.2), respectively. No significant differences in the genotypic frequencies of CYP1A1 T3801C and GSTM1 polymorphisms were observed between controls and cases in both men and women.

CONCLUSION

These results suggest that the Val allele of CYP1A1 Ile462Val polymorphism and the Pro allele of TP53 Arg72Pro polymorphism contribute to an increased risk of GBC among Japanese women and men, respectively.

Association between the TP53 codon72 polymorphism and oral cancer risk and prognosis

The TP53 codon72 polymorphism has recently been extensively studied to determine the risk factor for carcinogenesis. However, there are few reports about the relationship between the TP53 codon72 polymorphism and oral cancer risk or post treatment prognosis. We evaluated the genotypic distribution of the TP53 codon72 polymorphism in 100 oral cancer cases and 271 non-cancer controls. There were no significant differences in the frequencies of the three genotypes (Arg/Arg, Arg/Pro, Pro/Pro) of the TP53 codon72 polymorphism between oral cancer cases and controls. However, stratifying by smoking status, we found that the adjusted odds ratio for non-smokers with the Pro/Pro genotype was significantly increased (adjusted OR=2.70, 95% confidence interval=1.07-6.82). We also found that the cases with the Pro/Pro genotype tended to have a shorter post-treatment survival compared with those with the Arg/Pro genotype (p=0.06). Our results suggest the Pro/Pro genotype of the TP53 codon72 polymorphism increases oral cancer risk in non-smokers and worsens their prognosis.

An increased lung cancer risk associated with codon 72 polymorphism in the TP53 gene and human papillomavirus infection in Mazandaran province, Iran

The TP53 gene has a polymorphism in exon 4 at codon 72 that presents the arginine or proline genotype. The association of TP53 codon 72 polymorphism with lung cancer risk has been studied by several groups, although with inconsistent results. Our previous study showed that the human papillomavirus (HPV) infection is associated with the development of lung cancer in Mazandaran, north part of Iran (cases=25.6% versus controls=9.0%, P=0.002). The frequency of TP53 codon 72 polymorphism was studied in a north part Iranian group of 92 healthy controls and 141 lung cancer patients. The allelic distribution of the three genotypes (ArgArg, ArgPro, ProPro) in healthy normal controls was 46.1, 32.6 and 21.3%, respectively, which differs from that of lung cancer patients showing genotype frequency as 42.6, 49.6 and 7.8%. A relation between the presence of the Arg allele and lung cancer risk was observed. Our study reveals that Arg allele, active smoking and HPV infection are the important risk factors in lung cancer development in the north part of Iran, Mazandaran province.

Polymorphism of p53 gene codon 72 in Kuwaiti with coronary artery disease and diabetes

BACKGROUND AND AIM

Polymorphism in the p53 gene at codon 72 has been linked to the development of certain diseases including cancer. A possible association between such polymorphism and the development of coronary artery disease (CAD) and diabetes is being investigated, but no conclusive evidence has been reached yet. Our study is the first pilot study to be conducted on Kuwaitis suffering from CAD and diabetes, aiming at investigating the possible existence of the above association.

MATERIALS AND METHODS

We analyzed the genotype distribution and allele frequency of p53 gene at codon 72 in 158 CAD samples and 110 controls, and in 142 diabetic and 130 controls.

RESULTS

Analysis of CAD patients revealed an alarming significant association between the disease and the existence of diabetes (P=0.0007). Also, the CAD patients had significantly higher level of triglyceride (P<0.0001) and cholesterol (P<0.0001) as compared to control. As for the polymorphism in p53 gene codon 72, we could not detect any association with the genotype Pro/Pro, Pro/Arg or Arg/Arg distribution (P=0.28) or allele (Pro or Arg) frequency (P=0.25) in the CAD patients. Similarly, no association was found with the genotype Pro/Pro, Pro/Arg or Arg/Arg distribution (P=0.44) or allele (Pro or Arg) frequency (P=0.26) in the diabetic patients.

CONCLUSION

CAD seems to be strongly linked to diabetes in Kuwait. Polymorphism in the p53 gene at codon 72 revealed no significant association with the development of CAD or diabetes in Kuwait, which confirms other similar results obtained in the US and Asia.

p53 Arg72Pro polymorphism and risk of colorectal adenoma and cancer

A single nucleotide polymorphism (SNP) at codon 72 of the p53 gene (Arg72Pro) alters the p53 protein structure and affects its activity. We investigated this SNP in relation to colorectal adenoma and cancer among men and women from case-control studies nested within the Nurses' Health Study, the Health Professionals Follow-up Study and the Physicians' Health Study. Among 856 colorectal adenoma cases and 1,184 controls, we observed a modest association with p53 Arg72Pro genotype (multivariate odds ratio (OR) = 1.25, 95% confidence interval (CI) = 1.04-1.50 for Arg/Pro and Pro/Pro vs. Arg/Arg). This association did not vary by colorectal site or by sex. Among 442 colorectal cancer cases and 904 controls, we observed no significant overall association between p53 Arg72Pro genotype and colorectal cancer (multivariate OR = 1.14, 95% CI = 0.90-1.45). However, when colorectal site and sex was accounted for, the Pro carrier genotypes compared to Arg/Arg were associated with an increased risk of proximal colon cancers in women (multivariate OR = 2.59, 95% CI = 1.49-4.52) though not with distal colon or rectal cancers, while among men the same genotypes were associated with an increased risk of distal colon cancers (multivariate OR = 2.09, 95% CI = 1.28-3.40) but not proximal colon or rectal cancers. Our results suggest that Arg72Pro may play a role in the early stages of colorectal neoplasia and possibly in progression to invasive disease, depending on site and sex.

Evaluation of p53 codon 72 polymorphism in adenocarcinomas of the colon and rectum in La Plata, Argentina

AIM: To evaluate the potential association between p53 codon 72 polymorphism and sporadic colorectal adenocarcinoma development, and human papillomavirus (HPV) infection.

METHODS: One-hundred and nine controls and 53 patients with colon cancer from the city of La Plata, Argentina were analyzed. p53 codon 72 genotypes and HPV infection were identified using allele-specific polymerase chain reaction and nested polymerase chain reaction, respectively.

RESULTS: The differences in the distribution of p53 codon 72 polymorphism between the cases and controls were statistically significant. The arginine allele had a prevalence of 0.65 in controls and 0.77 in cases. The corresponding odds ratio for the homozygous arginine genotype was 2.08 (95% CI, 1.06-4.05; P<0.05). Lack of association was found between p53 polymorphism and HPV infection in the set of adenocarcinomas.

CONCLUSION: The findings of the present study indicate that p53 codon 72 arginine homozygous genotype may represent a genetic predisposing factor for colon cancer development. However, further studies are needed in order to elucidate the role of p53 codon 72 polymorphism in colorectal cancer.

p53 codon 72 polymorphism in basal cell carcinoma of the skin

Basal cell carcinoma (BCC) is the most prevalent cancer in Iran. A common polymorphism at codon 72 of exon 4 of p53 tumor suppressor gene has been reported to be associated with increased inheritable susceptibility to several cancers. In the present study the frequency of p53 codon 72 polymorphism in 91 patients with BCC of skin, compared to 465 healthy normal individuals, was investigated. In total, there was no significant difference in the p53 genotypes between patients and controls. However, there was an apparent increase in the Arg/Arg genotype among those BCC patients who had a history of occupational sun exposure, compared to non-exposed patients (46.3% vs. 23.1%, P=0.11). A trend of increase in the frequency of Arg allele among sun-exposed patients was also observed (69.4% vs. 53.8%, P=0.07). Comparison of the genotype frequencies between sunexposed patients and normal controls confirmed the accumulation of Arg/Arg genotype in these patients (46.3% vs. 34.8%, P = 0.07). In addition, the frequency of Arg allele was significantly higher in sunexposed patients compared to controls (69.4% vs. 58.2%, P=0.03). Our results suggest that Arg allele at codon 72 of p53 gene might affect the risk of ultraviolet-induced basal cell carcinoma.

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.

Increased risk of non-small cell lung cancer and frequency of somatic TP53 gene mutations in Pro72 carriers of TP53 Arg72Pro polymorphism

The aim of this study was to assess whether the TP53 Arg72Pro polymorphism is associated with an increased risk of non-small cell lung cancer (NSCLC). Additionally, in NSCLC patients, we investigated a potential association between this polymorphism and somatic TP53 gene mutations in tumour cells. The study group included 240 NSCLC patients who underwent curative pulmonary resection. The control group (576 healthy subjects) was matched for sex and cigarette smoking. TP53 Arg72Pro polymorphism was determined by denaturing high-performance liquid chromatography. Tumours from 157 NSCLC patients were analysed for mutation in TP53 exons 5-8 by single strand conformation polymorphism, followed by sequencing of samples with different band pattern. Tumours from the remaining 83 patients were subjected to a direct sequencing of TP53 exons 5-8. The proportion of Pro homo/heterozygotes versus Arg homozygotes was significantly higher in NSCLC patients (54%) than in controls (46%, p = 0.034). The crude odds ratio for NSCLC development in Pro72 allele carriers was 1.39 (95% CI: 1.03-1.88). When adjusted for sex, age and smoking status in the multivariate logistic regression model, odds ratio for NSCLC development was 1.28 (95% CI: 0.91-1.80). Somatic TP53 mutations were found in 62 out of 240 NSCLC patients (26%), more frequently in Pro carriers (31%) than in Arg homozygotes (20%, p = 0.06). These results indicate that the TP53 codon 72 Pro allele may increase the risk of NSCLC. Additionally, the correlation between Pro72 and somatic TP53 mutations suggests that Pro72 allele carriers may be predisposed to tumour development along a p53 associated form of NSCLC, a finding that warrants further investigations.

Association of p53 Codon 72 Polymorphism with Risk of Hypopharyngeal Squamous Cell Carcinoma in Taiwan

BACKGROUND

p53 polymorphism at codon 72 is a known risk marker for various malignancies, but it has not been studied in hypopharyngeal cancer. This study investigated the genotype distribution of p53 codon 72 polymorphism in hypopharyngeal cancer patients and non-cancer controls matched for age, gender, alcohol consumption and smoking habit.

METHODS

Genomic DNA was extracted from peripheral blood cells of 53 patients with hypopharyngeal cancer and 53 non-cancer controls. Codon 72 polymorphism of p53 was identified by polymerase chain reaction-restriction fragment length polymorphism.

RESULTS

Patients with hypopharyngeal cancer had higher frequencies of Pro/Pro (26.4% vs. 13.2%) and Pro/Arg (51.0% vs. 45.3%) but lower frequencies of Arg/Arg (22.6% vs. 45.1%) compared to controls. Compared to Arg/Arg genotypes, Pro/Pro genotypes had a relative risk of hypopharyngeal cancer of 3.667 (95% confidence interval, 1.16-11.56; p = 0.03). As a group, patients with Pro/Pro or Arg/Pro who were carriers of the Pro allele had a higher relative risk of hypopharyngeal cancer compared to Arg homozygous carriers (odds ratio, 2.415; 95% confidence interval, 1.04-5.64; p = 0.04).

CONCLUSION

This study demonstrated that p53 codon 72 Pro homozygosity is associated with a higher risk of developing hypopharyngeal cancer.

The associations of p53 overexpression with p53 codon 72 genetic polymorphism in esophageal cancer

Variations in p53 codon 72 have been identified as significant predisposing factors for various cancers, but molecular mechanisms remain unclear. We investigated associations of p53 overexpression with codon 72 variants and other factors with esophageal cancer. Status of p53 overexpression was determined by immunohistochemical staining. Codon 72 polymorphisms and mutation of p53 was identified by PCR-RFLP and direct sequencing from exons 4 to 9, respectively. We evaluated 126 patients who underwent esophagectomy in the National Taiwan University Hospital, and found that the status of p53 overexpression was significantly influenced by presence of codon 72 polymorphisms. After adjustment for other possible confounders, the incidence of p53 overexpression was significantly decreased in patients with Pro/Pro genotype with an odds ratio (OR) of 0.21 (95% CI: 0.067-0.64) (p = 0.0065) compared with incidence in patients with Arg/Arg genotype. The incidence of p53 overexpression was additively increased with environmental exposure to cigarette smoke, alcohol, and areca quid. When compared with individuals exposed to only one of these environmental risk factors, patients who had exposure to two or three risk factors had ORs of 6.11 (95% CI: 1.80-20.75) and 6.22 (95% CI: 1.81-21.34) for p53 overexpression, respectively. Elderly patients (age >70 years) were also more likely to have p53 overexpression, with an OR of 5.63 (95% CI: 1.53-20.64) compared with overexpression among patients aged less than 55 years. Forty-one patients received further evaluation of p53 mutation. There was also a higher incidence of, but without reaching a statistical significance, p53 mutation in patients with p53 overexpression (OR[95% CI]: 2.18 [0.52-9.6]) and codon 72 Arg/Arg genotype (OR [95% CI] of 0.8 [0.13-4.2], comparing genotypes of Pro/Pro and Arg/Pro with Arg/Arg). Our data provide the first observations that the presence of p53 codon 72 variants can be a significant factor influencing p53 overexpression in esophageal cancer, with overexpression also influenced by combined or prolonged environmental exposures.

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.

Genotoxicity of tobacco smoke and tobacco smoke condensate: a review

This report reviews the literature on the genotoxicity of mainstream tobacco smoke and cigarette smoke condensate (CSC) published since 1985. CSC is genotoxic in nearly all systems in which it has been tested, with the base/neutral fractions being the most mutagenic. In rodents, cigarette smoke induces sister chromatid exchanges (SCEs) and micronuclei in bone marrow and lung cells. In humans, newborns of smoking mothers have elevated frequencies of HPRT mutants, translocations, and DNA strand breaks. Sperm of smokers have elevated frequencies of aneuploidy, DNA adducts, strand breaks, and oxidative damage. Smoking also produces mutagenic cervical mucus, micronuclei in cervical epithelial cells, and genotoxic amniotic fluid. These data suggest that tobacco smoke may be a human germ-cell mutagen. Tobacco smoke produces mutagenic urine, and it is a human somatic-cell mutagen, producing HPRT mutations, SCEs, microsatellite instability, and DNA damage in a variety of tissues. Of the 11 organ sites at which smoking causes cancer in humans, smoking-associated genotoxic effects have been found in all eight that have been examined thus far: oral/nasal, esophagus, pharynx/larynx, lung, pancreas, myeoloid organs, bladder/ureter, uterine cervix. Lung tumors of smokers contain a high frequency and unique spectrum of TP53 and KRAS mutations, reflective of the PAH (and possibly other) compounds in the smoke. Further studies are needed to clarify the modulation of the genotoxicity of tobacco smoke by various genetic polymorphisms. These data support a model of tobacco smoke carcinogenesis in which the components of tobacco smoke induce mutations that accumulate in a field of tissue that, through selection, drive the carcinogenic process. Most of the data reviewed here are from studies of human smokers. Thus, their relevance to humans cannot be denied, and their explanatory powers not easily dismissed. Tobacco smoke is now the most extreme example of a systemic human mutagen.

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.