No association between p73 G4C14-to-A4T14 polymorphism and the risk of lung cancer in a Korean population

Association between TP73 G4C14-A4T14 polymorphism and different cancer types: an updated meta-analysis of 55 case-control studies

OBJECTIVE

The TP73 G4C14-A4T14 variant has been associated with elevated cancer risk, but the evidence is inconclusive. We performed a meta-analysis to clarify the role of this variant in cancer development.

METHODS

Eligible literature was selected by searching PubMed, Google Scholar, Cochrane Library, and Embase. The meta-analysis was performed using Review Manager 5.4.

RESULTS

A meta-analysis of 55 case-control studies showed that the G4C14-A4T14 variant was significantly associated with overall cancer development in five genetic models, including the allele model (AM), codominant model 1 (COD1), COD2, dominant model (DM), and over-dominant model (OD). Sub-group analysis based on ethnicity showed significantly higher risks in Africans in COD2 and RM and in Whites in AM, COD2, DM, and recessive model (RM). Cancer-specific subgroup analysis identified significant risks of gynecological (ovarian, cervical, and endometrial cancer), colorectal, oral, head and neck, and other cancers. Moreover, hospital-based controls revealed significant cancer risks in the AM, COD1, COD2, DM, and RM genetic models. Our findings were confirmed by trial sequential analysis.

CONCLUSION

This meta-analysis confirmed that TP73 G4C14-A4T14 significantly elevates the overall cancer risk, especially in White, African, and hospital-based populations, and specifically predisposes individuals to gynecological, colorectal, oral, and head and neck cancers.This meta-analysis was registered at INPLASY (registration number: INPLASY202210070).

Case–control study on TP73 rs1801173 C > T gene polymorphism and susceptibility to gastric cancer in a Chinese Han population

Background

This study investigated the role of TP73 gene polymorphism, rs1801173on risk of gastric cancer.

Methods

We conducted a case-controlled study including 577 primary gastric cancer and 678 normal control cases. The target gene fragment was amplified using PCR using blood samples collected from patients. Allele analysis and genotyping were performed using snapshot method.

Results

The findings showed that the control group had consistent genotype frequency distribution and presented Hardy–Weinberg equilibrium. The results showed no significant differences in sex, drinking history and age distributions between subjects with the polymorphism and subjects in the control group. Smoking status was correlated with incidence of gastric cancer (P = 0.006). The rs1801173 locus of TP73 gene contained 3 genotypes including: TT, CT, and CT. Logistic regression analysis showed that distribution of recessive model and dominant model was comparable between the two groups before (P = 0.688; 0.937) or after (P = 0.703; 0.990) adjusting for confounders. The distribution frequency in case group was not significantly different relative to that of the control group (P = 0.763).

Conclusion

Smoking can independently influence the risk of gastric cancer. TP73 gene rs1801173 polymorphism was not significantly correlated with risk of gastric cancer.

TP73 G4C14-A4T14 polymorphism and cancer susceptibility: evidence from 36 case-control studies

G4C14-A4T14 polymorphism of TP73 gene has been reported with a potential association in cancer risks through affected cell homeostasis; however the results were not consistent. We performed a comprehensive meta-analysis to explore the associations between G4C14-A4T14 polymorphism and cancer susceptibility. Extensive retrieve was performed in PubMed, EMBASE, Google Scholar, Web of Science, Wanfang database and CNKI database up to May 20, 2018. Odds ratios (ORs) and 95% confidence intervals (CIs) were conducted to evaluate the overall strength of the associations in five genetic models, as well as in subgroup analyses. Q-test, false-positive report probability analysis and trial sequential analysis, Egger’s test and Begg’s funnel plot were applied to evaluate the robustness of the results. In silico analysis was managed to demonstrate the relationship of TP73 expression correlated with cancer tissues. Finally, 36 case–control studies with a total of 9493 cancer cases and 13,157 healthy controls were enrolled into the meta-analysis. The pooled results present a significantly higher risk of G4C14-A4T14 polymorphism in all the five genetic models, as well as in the subgroups of Caucasian, cervical cancer, colorectal cancer, H-B subgroup and comfort to Hardy–Weinberg equilibrium subgroup. In silico analysis revealed that the expression of TP73 in cervical cancer tissue is higher than it in corresponding normal tissue, as well as in cervical cancer. All in all, TP73 G4C14-A4T14 polymorphism causes an upgrade cancer risk, especially in Caucasian population. G4C14-A4T14 polymorphism might be a potential biomarker for judging the tumorigenesis of cervical cancer and colorectal cancer.

Relationship of p73 gene polymorphism and additional gene-smoking and gene-obesity interaction with non-small cell lung cancer risk

Aim

The aim of this study was to investigate the impact of G4C14-to-A4T14 polymorphism within P73 gene and additional interactions with current smoking and obesity on non-small cell lung cancer (NSCLC) risk in a Chinese population.

Results

Logistic regression analysis showed a significant association between genotypes of the AT allele in G4C14-to-A4T14 and decreased NSCLC risk. NSCLC risk was significantly lower in carriers of the G4C14-to-A4T14- AT allele than those with GC/GC genotype (AT/AT + GC/AT versus GC/GC), adjusted OR (95%CI) = 0.68 (0.55–0.93). We also found that the OR (95%CI) was 1.88 (1.32-2.47) for current smokers compared with never smokers and 0.69 (0.40–0.95) for obese subjects compared to participants with normal BMI. Never smokers with AT/AT or GC/AT of the G4C14-to-A4T14 genotype have the lowest NSCLC risk compared with smokers with the GC/GC genotype after covariates adjustment, OR (95%CI) = 0.52 (0.26-0.87). Obese participants with G4C14-to-A4T14- AT/AT or GC/AT genotype have the lowest NSCLC risk compared with non- obese subjects with the GC/GC genotype after adjusting for covariates, OR (95% CI) = 0.56 (0.33–0.85).

Materials and Methods

A logistic regression model was used to examine the association between G4C14-to-A4T14 polymorphism and NSCLC, and its interaction with current smoking and obesity. The odds ratios (OR) and 95% confident intervals (95%CI) were calculated.

Conclusions

Our results support an important association between the G4C14-to-A4T14 and decreased NSCLC risk and additional impact of an interaction between G4C14-to-A4T14 and smoking or obesity on NSCLC risk.

Association of p73 gene G4C14-A4T14 polymorphism and MDM2 gene SNP309 with non-small cell lung cancer risk in a Chinese population

The present study aimed to investigate the association of p73 G4C14-A4T14 polymorphism and murine double minute 2 (MDM2) 309 T/G single nucleotide polymorphisms (SNPs) with the risk of developing non-small cell lung cancer (NSCLC) in Sothern China. The p73 and MDM2 genotypes of peripheral blood DNA from 186 patients with NSCLC and 196 normal controls were detected by polymerase chain reaction (PCR) with confronting two-pair primers (CTPP) and high resolution melting (HRM), respectively. The results of genotyping were consistent with those of direct sequencing. The p73 AT/AT [odds ratio (OR)=0.46; 95% confidence interval (CI)=0.22-0.97] and MDM2 TT (OR=0.48; 95% CI=0.26-0.86) genotypes were associated with a decreased risk of developing NSCLC compared with that of the p73 GC/GC and MDM2 GG genotypes, respectively. In addition, the interaction between the p73 and MDM2 polymorphisms reduced the risk of developing NSCLC in multiple ways (OR=0.13; 95% CI=0.03-0.59) for subjects carrying both the p73 AT/AT and MDM2 TT genotypes. Therefore, the SNP in p73 G4C14-A4T14 and the MDM2 309 polymorphism may be markers of genetic susceptibility to NSCLC in a Chinese population, and there is a possible gene-gene interaction involved in the incidence of NSCLC.

Association between a p73 gene polymorphism and genetic susceptibility to non-small cell lung cancer in the South of China

BACKGROUND

This study aimed to identify any association between the p73 gene G4C14-to-A4T14 polymorphism and risk of non-small cell lung cancer (NSCLC) in the south of China.

MATERIALS AND METHODS

We genotyped the p73 gene polymorphism of peripheral blood DNA from 168 patients with NSCLC and 195 normal controls using HRM (high resolution melting) and PCR-CTPP (polymerase chain reaction with confronting two-pair primers).

RESULTS

The results of genotyping by HRM and PCR-CTPP were consistent with direct sequencing, the p73 genotype distribution in 168 lung cancer patients being as follows: GC/GC 101 cases (60.1%), GC/ AT 59 cases (35.1%), AT/AT 8 cases (4.8%). The carriers of AT/AT genotype had a significantly reduced risk of NSCLC (OR=0.370; 95%CI: 0.170-0.806; p=0.010) as compared with non-carriers. However, we found no relations between p73 genotypes and histological type (p=0.798, x2=0.452), tumor stage (p=0.806, x2=0.806), or lymph node metastasis (p=0.578, x2=1.098).

CONCLUSIONS

Our findings suggest that the p73 G4C14-to-A4T14 polymorphism may be a modifier of NSCLC susceptibility in the Chinese population.

Association of p73 G4C14-to-A4T14 polymorphism with non-small cell lung cancer risk

The p73 gene is a structural and functional homolog of the p53 gene, which has a crucial role in mediating cell cycle arrest and apoptosis. Numerous previous studies have investigated the polymorphism of p73 G4C14-to-A4T14 at exon 2, as it was suggested to affect gene expression and result in functional significance. However, the correlation of this polymorphism with clinicopathological variables of patients with non-small cell lung cancer (NSCLC) remains to be elucidated. The aim of the present study was to examine the association between the gene polymorphism of p73 G4C14-to-A4T14 and the risk of developing NSCLC. The single-nucleotide polymorphisms of p73 G4C14-to-A4T14 were genotyped using polymerase chain reaction with confronting two-pair primers and direct DNA sequencing in 186 NSCLC patients and 196 cancer-free controls. χ²-tests and logistic regression analysis were used to analyze the experimental data, including the determination of odds ratio (OR), 95% confidence intervals (95% CIs) and P-values. The results demonstrated that the AT/AT genotype was associated with a significantly decreased risk of NSCLC (P=0.010; OR=0.370; 95% CI=0.170-0.806) compared with the GC allele genotypes including GC/GC and GC/AT. In addition, carriers of the AT allele exhibited a significantly reduced risk of NSCLC (P=0.038; OR=0.713; 95% CI=0.517-0.983) compared with non-carriers. In conclusion, these results indicated that the p73 G4C14-to-A4T14 polymorphism was a potential marker of NSCLC genetic susceptibility. However, further studies with a larger population are required in order to confirm these results.

Role of p73 Dinucleotide Polymorphism in Prostate Cancer and p73 Protein Isoform Balance

Background. Molecular markers for prostate cancer (PCa) risks are currently lacking. Here we address the potential association of a dinucleotide polymorphism (DNP) in exon 2 of the p73 gene with PCa risk/progression and discern any disruption of p73 protein isoforms levels in cells harboring a p73 DNP allele. Methods. We investigated the association between p73 DNP genotype and PCa risk/aggressiveness and survival by fitting logistic regression models in 1,292 incident cases and 682 controls. Results. Although we detected no association between p73 DNP and PCa risk, a significant inverse relationship between p73 DNP and PCa aggressiveness (AT/AT + GC/AT versus GC/GC, OR = 0.55, 95%Cl = 0.31–0.99) was detected. Also, p73 DNP is marginally associated with overall death (dominant model, HR = 0.76, 95%Cl = 0.57–1.00, P = 0.053) as well as PCa specific death (HR = 0.69, 95%Cl = 0.45–1.06, P = 0.09). Western blot analyses for p73 protein isoforms indicate that cells heterozygous for the p73 DNP have lower levels of ∆Np73 relative to TAp73 (P < 0.001). Conclusions. Our findings are consistent with an association between p73 DNP and low risk for PCa aggressiveness by increasing the expressed TAp73/∆Np73 protein isoform ratio.

p73 G4C14-to-A4T14 polymorphisms are positively correlated with triple-negative breast cancer in southwestern China

p73 gene shares structural and functional similarities to p53 and plays an important role in modulating cell cycle arrest and apoptosis. A common non-coding polymorphism of p73 G4C14-to-A4T14 (rs2273953 and rs1801173) at exon 2 may affect gene expression, thus, it may lead to functional significance. The correlation of this polymorphism with clinicopathologic variables of patients with breast cancer has not been investigated. In this study, single-nucleotide polymorphisms (SNPs) of p73 G4C14-to-A4T14 were genotyped by Sequenom MassArray-iPLEX GOLD System in 170 patients with breast cancer. Data were analyzed via t test, chi-square test, and logistic regression analysis. There was no significant correlation between p73 G4C14-to-A4T14 polymorphisms and the patient characteristics, such as clinical TNM stage, menopausal status, axillary lymph node metastasis, pathological type, estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2). No significant relationship was observed between the p73 G4C14-to-A4T14 polymorphism and p73 protein expression in cancer tissues. The frequency of GC/GC genotype in patients with triple-negative breast cancer (TNBC) was 78.9 %, that of patients with others was 57.6 %, and the difference had statistical significance (χ ( 2 ) = 5.74, P = 0.02). p73 G4C14-to-A4T14 polymorphisms were negatively correlated with chemosensitivity for anthracycline-based chemotherapy in breast cancer (P > 0.05). p73 G4C14-to-A4T14 polymorphisms are positively correlated with TNBC, and p73 gene may play a critical role in a novel therapeutic strategy to TNBC. Additional larger studies are required to test these hypotheses.

Association of p73 G4C14-A4T14 polymorphisms with genetic susceptibilities to breast cancer: a case-control study

The aim of this study was to evaluate the association of p73 G4C14-A4T14 polymorphisms with susceptibility to breast cancer in Chongqing women of Han Nationality in China. In a case-control study, single-nucleotide polymorphisms of p73 G4C14-A4T14 at exon 2 were genotyped by Sequenom MassArray(®) iPLEX GOLD System in 170 patients with breast cancer and 178 healthy controls. Data were analyzed via t test, Chi-square test, and logistic regression analysis. The distribution of p73 genotypes and allelotypes had no significant difference between patients with breast cancer and healthy controls (χ(2) = 2.750, P = 0.253; χ(2) = 2.195, P = 0.138). More risk of developing triple negative breast cancer (TNBC) was found in the individuals who carried with GC/GC genotype than individuals carried with GC/AT and AT/AT genotypes (OR = 2.99; 95 % CI, 1.30-6.89; P = 0.010). p73 G4C14-A4T14 polymorphisms are closely associated with the increased risk for TNBC in Chongqing women of Han Nationality in China; GC/GC genotype is susceptible genotype for TNBC in Chongqing women of Han Nationality in China. The patients with breast cancer who carried with GC/GC genotype may have bad prognosis. Additional larger studies are required to confirm these findings.

The p73 G4C14-to-A4T14 polymorphism is associated with risk of lung cancer in the Han nationality of North China

p73, a structural and functional homolog of p53, plays an important role in tumor carcinogenesis. Previous studies have suggested that the association between the p73 G4C14-to-A4T14 polymorphism and the risk of lung cancer, but the results have not been entirely consistent. We examined whether the p73 G4C14-to-A4T14 polymorphism was related to the risk of developing lung cancer in a Chinese population. The p73 G4C14-to-A4T14 polymorphism was genotyped in 293 lung cancer patients and 380 cancer-free controls of Han nationality in North China using PCR-RFLP. Multivariate logistic regression analysis was used to calculate adjusted odds ratios (ORs) and 95% confidence intervals (95% CIs). We observed that compared with the GC/GC genotype, the genotypes containing AT allele (GC/AT + AT/AT genotypes) were associated with significantly increased susceptibility to lung cancer (OR, 1.48; 95% CI, 1.08-2.02; P = 0.014). In addition, compared with the GC/GC genotype, the GC/AT genotype was also significantly associated with increased susceptibility to lung cancer (OR, 1.46; 95% CI, 1.06-2.02; P = 0.046). Our findings suggest that the p73 G4C14-to-A4T14 polymorphism contributes to the risk of developing lung cancer in Chinese population.

Association between the p73 exon 2 G4C14-to-A4T14 polymorphism and cancer risk: a meta-analysis

The TP53 homolog p73 is structurally and functionally similar to TP53 and plays an important role in modulating cell-cycle control, apoptosis, and cell growth. G4C14-to-A4T14 is the most commonly studied polymorphism of this gene for its association with risk of cancers, but the results are confusing rather than conclusive. We performed a meta-analysis using 21 eligible studies with a total of 7581 patients and 10,413 controls to summarize the data for an association between the p73 G4C14-to-A4T14 polymorphism and cancer risk. Compared with the common GC/GC genotype, the AT carriers (AT/GC, AT/AT) had a 1.18-fold elevated risk of cancer (95% confidence interval [CI]=1.11-1.25, p<0.00001) in a dominant genetic model as estimated in a fixed effect model. The effect of the G4C14-to-A4T14 polymorphism was further evaluated through stratification analysis. In four lung cancer studies, the variant genotypes had a significantly increased risk of lung cancer (odds ratio [OR]=1.16, 95% CI=1.04-1.28, p=0.005). Similar phenomena were also found in two squamous cell carcinoma of the head and neck studies (OR=1.32, 95% CI=1.12-1.56, p=0.0010), two oral cancer studies (OR=1.57, 95% CI=1.26-1.95, p<0.0001), and three colorectal cancer studies (OR=1.23, 95% CI=1.01-1.50, p=0.04). Increased risk of cancer associated with G4C14-to-A4T14 variant genotypes was pronounced in Caucasians (OR=1.21, 95% CI=1.11-1.31, p<0.00001), the Japanese population (OR=1.24, 95% CI=1.01-1.52, p=0.04), and the Korean population (OR=1.27, 95% CI=1.07-1.52, p=0.007). Our meta-analysis suggests that the p73 G4C14-to-A4T14 polymorphism genotypes (GC/AT+AT/AT) may be associated with an increased risk of cancer in most cancer types and ethnicities.

Relationship between TP73 polymorphism (G4C14-A4T14) and cancer risk: a meta-analysis based on literatures

The tumor protein p73 (TP73) gene belongs to the TP53 gene family and functions in the induction of apoptosis or cell-cycle arrest. The TP73 polymorphism (G4C14-A4T14) has been reported and many studies have focused on the role of this polymorphism in various cancers. However, the data reported for most individual cancer types were limited and not able to support a convincible conclusion. Hence, in this study, we explored the relationship between TP73 polymorphism (G4C14-A4T14) and cancer risk by carrying out a comprehensive meta-analysis. Performing both the overall and subgroup meta-analyses with a total of 23 eligible studies (6635 cases and 7378 controls in all), we detected significant cancer risk variations in the overall analysis, as well as the subgroup analysis based on ethnicity for both Asians and Caucasians. In the subgroup analysis based on source of controls, significant associations were also observed in the hospital-based controls' subgroup yet not in the population-based controls' subgroup. Furthermore, in the subgroup analysis based on cancer types, significant associations were found in colorectal cancer's subgroup but not in other cancer types' subgroups. In summary, according to the results of our meta-analysis, the TP73 polymorphism (G4C14-A4T14) probably associates with cancer risk.

Combined analysis of the association between p73 G4C14-to-A4T14 polymorphisms and cancer risk

P73 is a structural and functional homologue of p53, and plays an important role in regulating cell cycle and apoptosis. A potentially functional polymorphism (designated as p73 G4C14-to-A4T14) has been identified in a region in exon 2 of the p73 gene, which may theoretically form a stem-loop structure and thereby affect p73 expression. Several investigations have reported the correlation between p73 G4C14-to-A4T14 polymorphism and cancer risk. However, the results are inconclusive. To further assess the association between p73 polymorphism and cancer risk, we performed meta-analysis of the data sets obtained from 26 individual studies involving 8,148 cancer patients and 8,150 controls. The association between p73 G4C14-to-A4T14 polymorphism and cancer risk was determined by crude odd ratios (OR) with 95% CI (confidential interval). AT-allele carriers were found to have a significantly increased risk of cervical cancer (AT/GC vs. GC/GC, OR = 1.63, 95% CI = 1.14-2.33; AT/AT + AT/GC vs. GC/GC, OR = 1.49, 95% CI = 1.05-2.10), colorectal cancer (AT/AT vs. AT/GC + GC/GC, OR = 1.98, 95% CI = 1.25-3.12), head and neck cancer (AT/AT + AT/GC vs. GC/GC, OR = 1.44, 95% CI = 1.06-1.96) and other cancers (AT/AT vs. GC/GC, OR = 1.78, 95% CI = 1.24-2.57; AT/AT vs. AT/GC + GC/GC, OR = 1.80, 95% CI = 1.26-2.56). In the stratified analysis of ethnicity, a significantly elevated cancer risk was found in Caucasians (AT/AT + AT/GC vs. GC/GC, OR = 1.18, 95% CI = 1.08-1.30; allele AT vs. allele GC, OR = 1.15, 95% CI = 1.06-1.24). No significant association of p73 polymorphism with the cancer risk of smoking was detected by stratified analysis by smoking status. Together, our data suggest that the p73 G4C14-to-A4T14 may be a risk factor of cancer especially in Caucasians.

Role of p53 and p73 genes polymorphisms in susceptibility to esophageal cancer: a case control study in a northern Indian population

Genetic variants in p53 and in its homologue p73 may modulate Esophageal Cancer (EC) risk because they are supposed to influence cell cycle progression, apoptosis and DNA repair. Therefore, we aimed to evaluate the association of p53 intron3 16 bp duplication and p73 G4C14-to-A4T14 polymorphisms with susceptibility to EC in a northern Indian population in 255 EC patients and 255 age and sex matched healthy controls. We found that p53 intron3 16 bp duplication polymorphism was not associated with EC and its clinical characteristics. However, p73 G4C14-to-A4T14 polymorphism was associated with significant higher risk of EC (OR = 1.74, 95% CI = 1.16-2.60, P = 0.007) in an allele dose-dependent manner (P(trend) = 0.0047). Stratification of subjects on the basis of clinical characteristics showed that p73 AT genotype carriers were at significant increased risk of developing esophageal squamous cell carcinoma (OR = 1.78, 95% CI = 1.18-2.67, P = 0.006) at middle third tumor location (OR = 1.87, 95% CI = 1.18-2.97, P = 0.007) with lymph node metastasis (OR = 1.77, 95% CI = 1.04-3.02, P = 0.035). No interaction with environmental risk factors was observed with any of the studied polymorphisms. In summary, p73 G4C14-to-A4T14 polymorphism but not the p53 intron3 16 bp duplication polymorphism is associated with EC and its clinical characteristics in northern Indian population.

p73 G4C14 to A4T14 polymorphism is associated with colorectal cancer risk and survival

AIM: To analyze the association between the p73 G4C14-to-A4T14 polymorphism (a.k.a., the GC/AT variation) and colorectal cancer risk and survival in the Korean population, and to evaluate the relationships between p73 polymorphism and the p73 protein expression or clinicopathological characteristics of colorectal cancer.

METHODS: Three hundred and eighty-three histologically confirmed cases and 469 healthy controls, recruited at one teaching hospital in Pusan, Korea from 2001 and 2007, were genotyped for p73 G4C14-to-A4T14 by PCR with confronting two-pair primers (PCR-CTPP) and the expression profile of p73 in cancer tissues (n = 383) was analyzed by immunohistochemistry.

RESULTS: Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated by unconditional logistic regression model adjusted for age and gender. Compared with the GC/GC genotypes, the GC/AT and AT/AT genotypes were significantly associated with colorectal cancer risk (GC/AT vs GC/GC: OR = 1.46, 95% CI: 1.10-1.94; AT/AT vs GC/GC: 1.72, 0.98-3.03; P_trend = 0.01). When stratified by age and gender, the association was restricted to those less than 60 years of age (GC/AT or AT/AT vs GC/GC: 2.22, 1.39-3.55) and male (GC/AT or AT/AT vs GC/GC: 1.91, 1.31-2.77). The expression of p73 was associated with invasion depth (P = 0.003) and advanced Duke’s stage (P = 0.06) of colorectal cancer. The patients with the GC/GC genotype were associated with worse survival compared with those with the other genotypes (P = 0.02). However, no significant relationship was observed between the p73 G4C14-to-A4T14 polymorphism and p73 protein expression in cancer tissues.

CONCLUSION: Our results suggest that the p73 GC/AT polymorphism is associated with an increased colorectal cancer risk and survival in the Korean population.

Single-nucleotide polymorphisms in the p53 signaling pathway

The p53 tumor suppressor pathway is central both in reducing cancer frequency in vertebrates and in mediating the response of commonly used cancer therapies. This article aims to summarize and discuss a large body of evidence suggesting that the p53 pathway harbors functional inherited single-nucleotide polymorphisms (SNPs) that affect p53 signaling in cells, resulting in differences in cancer risk and clinical outcome in humans. The insights gained through these studies into how the functional p53 pathway SNPs could help in the tailoring of cancer therapies to the individual are discussed. Moreover, recent work is discussed that suggests that many more functional p53 pathway SNPs are yet to be fully characterized and that a thorough analysis of the functional human genetics of this important tumor suppressor pathway is required.

Polymorphisms at p53, p73, and MDM2 loci modulate the risk of tobacco associated leukoplakia and oral cancer

Polymorphisms at loci controlling cellular processes such as cell cycle, DNA repair, and apoptosis may modulate the risk of cancer. We examined the association of two linked polymorphisms (G4C14-A4T14) at p73 and one polymorphism (309G > T) at MDM2 promoter with the risk of leukoplakia and oral cancer. The p73 and MDM2 genotypes were determined in 197 leukoplakia patients, 310 oral cancer patients and in 348 healthy control subjects. The p73 GC/AT genotype increased the risk of leukoplakia (OR = 1.6, 95% CI = 1.1-2.3) and oral cancer (OR = 2.4, 95% CI = 1.7-3.3) but the 309G > T MDM2 polymorphism independently could not modify the risk of any of the diseases. Stratification of the study population into subgroups with different tobacco habits showed that the risk of the oral cancer is not modified further for the individuals carrying p73 risk genotype. However, leukoplakia patients with smokeless tobacco habit showed increased risk with combined GC/AT and AT/AT (OR = 3.0, 95% CI = 1.3-7.0) genotypes. A combined analysis was done with our previous published data on p53 codon 72 pro/arg polymorphism. Analysis of pair wise genotype combinations revealed increase in risk for specific p73-MDM2 and p73-p53 genotype combinations. Finally, the combined three loci analyses revealed that the presence of at least one risk allele at all three loci increases the risk of both leukoplakia and oral cancer.

A case-control study on the effect of p53 and p73 gene polymorphisms on gastric cancer risk and progression

The p53 protein and its functional homologue p73 share several functions in modulating cell-cycle control and apoptosis. Based on the functional interaction between p53 and p73 in carcinogenesis, we investigated the combined effect of p73 G4C14-to-A4T14 and p53 gene polymorphisms and their interaction with selected environmental factors, on the risk for gastric cancer in a hospital-based case-control study conducted in Italy. The effect of these polymorphisms on cancer progression was also investigated. One hundred and fifteen gastric cancer cases and 295 hospital controls were genotyped for p73 G4C14-to-A4T14, and p53 exon 4 (Arg72Pro), intron 3 and intron 6 polymorphisms. An increased risk for gastric cancer was found to be associated with the inheritance of the p73 homozygous variant genotype among the gastric cancer intestinal histotype (odds ratio (OR)=6.75; 95% confidence interval (95% CI)=1.88-24.24). An effect modification of the p73 variant allele by gender was observed [(OR=2.82; 95%CI=1.24-6.40) among females, versus an OR of 0.70 (95%CI=0.32-1.54) among males; p-value for homogeneity among strata estimates =0.03]. Gene-gene interaction analyses demonstrated that individuals with combined p53 exon 4 and intron 6 variant alleles are borderline significantly protected from gastric cancer (OR=0.52; 95% CI=0.26-1.07; p-value for interaction =0.005), which was confirmed by the haplotype analysis. Finally, a poorer survival was observed among carriers of the variant allele of p53 intron 6 if compared with those carrying both wild-type alleles (p-value for log-rank test =0.02). This study shows that the p73 G4C14-to-A4T14 polymorphism may be a risk factor for gastric cancer, as reported from other studies in different tumour sites among Caucasians. Along with the protective effect of p53 exon 4-intron 6 allelic variants, already noted for breast and lung cancer, our results require confirmation from larger studies.