Role of p53 codon 72 polymorphism in chromosomal aberrations and mitotic index in patients with chronic hepatitis B

Polymorphisms of the p53 gene, which participates in DNA repair, can affect the functioning of the p53 protein. The Arg and Pro variants in p53 codon 72 were shown to have different regulation properties of p53-dependent DNA repair target genes that can affect various levels of cytogenetic aberrations in chronic hepatitis B patients. The present study aimed to examine the frequency of chromosomal aberrations and the mitotic index in patients with chronic hepatitis B and their possible association with p53 gene exon 4 codon 72 Arg72Pro (Ex4+119 G>C; rs1042522) polymorphism. Fifty-eight patients with chronic hepatitis B and 30 healthy individuals were genotyped in terms of the p53 gene codon 72 Arg72Pro polymorphism by PCR-RFLP. A 72-h cell culture was performed on the same individuals and evaluated in terms of chromosomal aberrations and mitotic index. A high frequency of chromosomal aberrations and low mitotic index were detected in the patient group compared to the control group. A higher frequency of chromosomal aberrations was detected in both the patient and the control groups with a homozygous proline genotype (13 patients, 3 control subjects) compared to patients and controls with other genotypes [Arg/Pro (38 patients, 20 control subjects) and Arg/Arg (7 patients, 7 control subjects)]. We observed an increased frequency of cytogenetic aberrations in patients with chronic hepatitis B. In addition, a higher frequency of cytogenetic aberrations was observed in p53 variants having the homozygous proline genotype compared to variants having other genotypes both in patients and healthy individuals.     

Common polymorphisms in the MDM2 and TP53 genes and the relationship between TP53 mutations and patient outcomes in glioblastomas

MDM2 SNP309 is associated with younger age of tumor onset in patients with Li-Fraumeni syndrome, and TP53 codon 72 polymorphism decreases its apoptotic potential. Glioblastomas frequently show genetic alterations in the TP53 pathway. In the present study, we assessed MDM2 SNP309 in 360 glioblastomas, and correlated these with patient age and survival, as well as other alterations in the TP53 pathway. Frequencies of the MDM2 SNP309 T/T, T/G and G/G genotypes in glioblastomas were 40%, 46% and 14%, respectively. Multivariate analysis showed that MDM2 SNP309 G/G allele was significantly associated with favorable outcome in female glioblastoma patients (hazard ratio 0.54; 95% CI = 0.32–0.92). There was a significant association between MDM2 SNP309 G alleles and TP53 codon 72 Pro/Pro in glioblastomas. Glioblastoma patients with TP53 codon 72 Pro/Pro genotype were significantly younger than Arg/Arg carriers (mean 50.2 vs. 56.1 years; P  = 0.018). Multivariate analysis showed that those with TP53 codon 72 Arg/Pro allele had significantly shorter survival than those with Arg/Arg allele (hazard ratio 1.35; 95% CI = 1.07–1.71). Detailed analyses revealed that TP53 codon 72 Pro allele was significantly associated with shorter survival among patients with glioblastomas carrying a TP53 mutation, and among those treated with surgery plus radiotherapy.     

Genetic polymorphisms in cell cycle regulatory genes MDM2 and TP53 are associated with susceptibility to lung cancer

The tumor suppressor TP53 pathway plays a crucial role in preventing carcinogenesis through its ability to impose cell cycle arrest and apoptosis following DNA damage and oncogene activation. MDM2 is a key negative regulator of the TP53 pathway and is overexpressed in many cancers as oncoprotein. We investigated the association between genetic variation in the promoter region of MDM2 (c.-5+309G>T, rs2279744:g.G>T) and the coding region of TP53 (c.215G>C, rs1042522:g.G>C, designated Arg72Pro) and the risk of developing lung cancer. The genotypes of 1,106 patients and 1,420 controls were determined by tetra-primer amplification refractory mutation system (ARMS)-PCR or PCR-based restriction fragment length polymorphism (RFLP). Associations with risk of lung cancer were estimated by logistic regression. We observed an increased lung cancer risk associated with the MDM2 GG (odds ratio [OR] = 1.83, 95% confidence interval [CI] = 1.45-2.32) and TG (OR = 1.33, 95% CI = 1.09-1.63) genotypes. An increased risk was also associated with the TP53 Pro/Pro genotype (OR = 1.47, 95% CI = 1.17-1.85, P = 0.003) compared to the Arg/Arg genotype. The gene-gene interaction of MDM2 and TP53 polymorphisms increased lung cancer risk in a supermultiplicative manner (OR for the presence of both MDM2 GG and TP53 Pro/Pro genotypes = 4.56, 95% CI = 2.76-7.54). Significant interactions were observed between these polymorphisms (respectively and jointly) and smoking (OR = 10.41, 95% CI = 5.26-20.58) for smokers with both the MDM2 GG and TP53 Pro/Pro genotypes. In conclusion, genetic polymorphisms in cell cycle regulatory genes MDM2 and TP53 contribute to the risk of developing lung cancer.     

Polymorphisms in TP53 are associated with risk and survival of osteosarcoma in a Chinese population

Osteosarcoma (OS) is the most frequent histological form of primary bone cancer in adolescence. TP53 is a tumor suppressor gene which is essential for regulating cell division and preventing tumor formation. The purpose of this study is to examine whether genetic mutations in the TP53 gene are associated with OS risk and survival in a Chinese population. Five polymorphisms in the TP53 gene were selected in a case-control study, including 210 OS patients and 420 cancer-free controls. We found that subjects carrying rs12951053 CC genotype and rs1042522 GG genotype were significantly associated with risk of OS [odds ratio (OR) = 1.68, 95% confidence intervals (CI): 1.05-2.68; OR = 1.89, 95% CI: 1.16-3.07] compared with subjects carrying the common genotypes. Results of haplotype analysis also showed that A-G-G-A-C haplotype (rs12951053, rs1042522, rs8064946, rs9895829 and rs12602273) conferred significant decreased risk of OS (OR = 0.37, 95% CI: 0.19-0.72) compared with A-C-G-A-C haplotype. Besides, rs1042522 was an independent prognostic factor for OS with hazard radio (HR) = 1.94 (95% CI: 1.03-3.65) in GG genotype than in CC genotype. Our data suggest that genetic mutations in the TP53 gene are associated with risk and survival of OS in Chinese population.     

TP53 codon 72 polymorphism and risk for cervical cancer in Portugal

High-risk human papillomavirus are essential for the development of cervical cancer; however, TP53 is the most frequently altered tumor suppressor gene among tumors and is described as a cofactor for cervical carcinogenesis. TP53 has two common polymorphic forms encoding either proline or arginine, at position 72, and the presence of homozygous arginine has been reported as a risk factor for cervical cancer in many populations. We evaluated the effect of this TP53 polymorphism in a northern Portuguese population. We analyzed blood samples of 385 women; 20 with low-grade squamous intraepithelial lesion (SIL), 56 with high-grade SIL, 164 with invasive cervical cancer, and 145 healthy controls, using allele specific-polymerase chain reaction methodology. We observed an increased frequency of the Arg/Arg genotype in the cancer group, but no statistical significance was found between cases and controls (P>0.05). Our results indicate that there is no association between the presence of the Arg allele in codon 72 of TP53 polymorphism and risk of cervical cancer in our population.     

广西人群白细胞介素17A基因rs3819024和rs1974226的多态性

目的 探讨白细胞介素17 A（IL-17A）基因rs3819024和rs1974226多态性在广西人群中的分布特点,比较不同种族和地区人群间两位点基因型和等位基因频率的差异。 方法 采用SNaPshot SNP技术和DNA测序法,检测443例广西人rs3819024和rs1974226 多态性,统计分析两位点基因型和等位基因频率与国际人类基因组单体型图计划公布的北京汉族人群（HapMap-CHB）、日本人群（HapMap-JPT）、欧洲人群（HapMap-CEU）和非洲人群（HapMap-YRI）的差异。结果 广西人群rs3819024存在 GG、GA和AA 3种基因型,而rs1974226存在CC、CT和TT 3种基因型,两位点基因型和等位基因频率在不同性别间比较,差异均无统计学意义(P>0.05)。广西人群rs3819024 基因型和等位基因频率与HapMap-CHB人群比较,差异均无统计学意义（P>0.05）,然而与 HapMap-JPT、HapMap-CEU和HapMap-YRI人群比较,差异均有统计学意义（P<0.01）。而广西人群rs1974226基因型和等位基因频率与HapMap-CHB和HapMap-JPT人群比较,差异均无统计学意义（P>0.05）,然而与HapMap-CEU和HapMap-YRI人群比较,差异均有统计学意义（P<0.05）。 结论 广西人群存在IL-17A基因rs3819024和rs1974226多态性,与其他种族和地区人群比较存在不同程度的差异。     

TP53 Arg72Pro polymorphism in Turkish patients with sporadic amyotrophic lateral sclerosis

Recently, Eve et al. (2007) reported that the expression of TP53 (NM_000546) was increased by 2.1-fold in whole spinal cord and 2.7-fold in the ventral horn of amyotrophic lateral sclerosis (ALS) patients. Based on this particular observation, we decided to evaluate whether the TP53 Arg72Pro polymorphism (rs1042522) (C215G) was implicated in the etiopathology of sporadic amyotrophic lateral sclerosis (SALS). Therefore, we genotyped 394 Turkish SALS patients and 439 matched healthy controls by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). We did not find any association between overall SALS patients with the TP53 Arg72Pro polymorphism and controls (χ² = 2.674; p = 0.263). Consequently the TP53 Arg72Pro polymorphism was not associated with SALS.     

Role of p53 Arg72Pro SNP in the pathogenesis of gliomas and its effect on serum level of p53

Gliomas account for almost 80 % of primary malignant brain tumors and are a major cause of morbidity and mortality more than any other tumor. The p53 gene is a tumor suppressor gene that plays a role in genomic stability, cell cycle control, and DNA repair after damage and apoptosis. Malfunction of the p53 pathway is a universal hallmark of human tumors with p53 codon 72 polymorphism reported to affect regulatory networks central to glioma development. The aim of work was to investigate the role of p53 Arg72Pro single nucleotide polymorphism (SNP) in the pathogenesis of gliomas and its effect on the serum level of p53. Forty-five glioma patients and 50 control subjects were included for whom genotyping for p53 Arg72Pro SNP by polymerase chain reaction-restriction fragment length polymorphism as well as measurement of serum p53 level were done. No statistically significant difference was observed in genotype distribution or allele frequency between cases and control and nor was there a significant difference in serum p53 level. In conclusion, in our work, no association was detected between p53 Arg72Pro SNP and the pathogenesis of gliomas, and neither was there an observed effect for the different genotypes on serum p53 levels.     

TP53 codon 72 polymorphism, p53 expression, and 1p/19q status in oligodendroglial tumors

The functional single-nucleotide polymorphism (SNP) in codon 72 of TP53 has been shown to be both a risk factor and a prognostic biomarker in various cancers. Such results were also reported in brain tumors, notably in astrocytomas. This SNP has never been precisely investigated in oligodendroglial tumors. We retrospectively analyzed blood samples of 275 oligodendroglial tumor patients for the TP53 codon 72 polymorphism and compared them with a series of 144 healthy controls. Arg/Arg, Arg/Pro, and Pro/Pro genotypes were found in 54.2 versus 60.4%, 39.3 versus 34.0%, and 7.3 versus 5.6% of patients and controls, respectively. This suggests no association between oligodendroglial tumors and the SNP in codon 72 of TP53. Similarly, no correlation was found among the TP53 codon 72 polymorphism and prognosis, p53 expression, and chromosomes 1p and 19q status.     

Proline homozygosity in codon 72 of TP53 is a factor of susceptibility to nasopharyngeal carcinoma in Tunisia

A common polymorphism at codon 72 of TP53, the gene encoding the tumor suppressor protein p53, encodes either arginine or proline. These variants may be associated with tumor susceptibility since they interfere with the ability of TP53 to activate apoptosis, and might account for ethnic variation in cancer frequency. Using a polymerase chain reaction-restriction fragment length polymorphism assay, we tested peripheral blood samples from 115 patients with nasopharyngeal carcinoma (NPC) and from 83 healthy individuals. Patients with NPC (Arg/Arg = 38.26%, Arg/Pro = 41.73%, and Pro/Pro = 20%) showed a significantly different percentage of the Pro/Pro genotype, compared with the control population (Arg/Arg = 39%, Arg/Pro = 54%, and Pro/Pro = 7%) (P = 0.0307). No significant difference was observed between TP53 codon 72 polymorphism and age, sex, histological grade, and metastasis. These results provide evidence that individuals with the Pro/Pro genotype have an increased risk of developing NPC in Tunisia.     

Polymorphisms of the TP53 codon 72 and WRN codon 1367 in individuals from Northern Brazil with gastric adenocarcinoma

Abstract Gastric cancer is the second most frequent type of neoplasia and also the second most common cause of death in the world. TP53 codon 72, which produces variant proteins with an arginine (Arg) or proline (Pro), has been reported to be associated with cancers of the lung, oesophagus, stomach and cervix. Werner’s syndrome (WS) is a premature ageing disease caused by a mutation in the WRN gene. The WRN protein acts as a DNA helicase and as an exonuclease. WRN codon 1367 produces variant proteins with an Arg or cysteine (Cys). This polymorphism has been studied, in order to understand the clinical impact of the molecular variants in WS and in age-related disorders. In the present study, the TP53 codon 72 and the WRN codon 1367 polymorphisms were investigated in 54 gastric adenocarcinoma patients (31 diffuse-type and 25 intestinal-type) and 54 controls. DNA samples were extracted, and PCR-RFLP was utilised for genotyping TP53 codon 72 and WRN codon 1367. The allele frequencies of the TP53 polymorphism were: Arg=0.74 and Pro=0.26. The allele frequencies of the WRN polymorphism were: Cys=0.73 and Arg=0.27. The crude genotypic frequencies in gastric cancer patients were similar to those of the controls, but in the WRN codon 1367 polymorphisms the mean age tended to be higher in the Arg/Arg genotypes. There also was an association, although not statistically significant, between the presence of Helicobacter pylori and the genotypes Cys/Cys and Cys/Arg and a higher percentage of cardia cancer among the Arg/Arg genotypes, and of non-cardia cancer among genotypes Cys/Cys and Cys/Arg. These findings may be a reflection of differences in the interaction between WRN codon 1367 polymorphisms and local factors in the stomach. To our knowledge, this is the first study to examine a genetic polymorphism of the WRN gene in cancer. The precise mechanisms of action of the TP53 and WRN polymorphisms involved in the aetiopathogeny of this disease need further investigation.     

p53基因第72位密码子多态与食管癌风险

目的 研究p53基因第７２位密码子Ａrg/Pro多态与食管癌遗传易感性的关系。方法 采用聚合酶链反应－－限制性片段长度多态性方法检测了９１例食管癌患者与２０４名正常对照组的p53 Arg/Pro基因型分布及差异。结果 正常对照组p53 Pro等位基因频率（０.588）与病例组（０.480）比较差异无显著性（Ｐ＝０.11）。但３种p53基因型频率在病例组和对照组的分布差异有显著性，病例组的Ｐro/Pro基因型频率（３９.6％）显著高于对照组（２１.1%）。携带Ｐro/Pro纯合变异基因型者患食管癌的风险比携带Ａrg/Arg纯合野生基因型者高２倍[校正比值比（odds ratio,OR）为２.18,95%可信区间（confidemce interval,CI）为１.10-4.35。杂合子基因型（Ａrg/Pro）与食管癌的遗传易感性无关（校正ＯＲ＝０.84％，９５％ＣＩ＝０.42－１.68）。吸烟增加食管癌风险（ＯＲ＝２.30,95%CI=1.30-4.12)，但与Ｐro/Pro基因型无协同作用。结论 p53基因第７２位密码子纯合突变是中国人的食管癌易感因素。     

Impact of the MDM2 SNP309 and p53 Arg72Pro polymorphism on age of tumour onset in Li-Fraumeni syndrome

Li-Fraumeni syndrome, resulting from p53 (TP53) germline mutations, represents one of the most devastating genetic predispositions to cancer. Recently, the MDM2 SNP309 (T-->G variation) was shown to be associated with accelerated tumour formation in p53 mutation carriers. The impact of the common p53 codon 72 polymorphism on cancer risk remains controversial. We therefore investigated the effect of these two polymorphisms in 61 French carriers of the p53 germline mutation. The mean age of tumour onset in MDMD2 SNP309 G allele carriers (19.6 years) was significantly different from that observed in patients homozygous for the T allele (29.9 years, p<0.05). For the p53 codon 72 polymorphism, the mean age of tumour onset in Arg allele carriers (21.8 years) was also different from that of Pro/Pro patients (34.4 years, p<0.05). We observed a cumulative effect of both polymorphisms because the mean ages of tumour onset in carriers of the MDM2G and p53Arg alleles (16.9 years) and those with the MDM2T/T and p53Pro/Pro genotypes (43 years) were clearly different (p<0.02). Therefore, our results confirm the impact of the MDM2 SNP309 G allele on the age of tumour onset in germline p53 mutation carriers, and suggest that this effect may be amplified by the p53 72Arg allele. Polymorphisms affecting p53 degradation therefore represent one of the rare examples of modifier genetic factors identified to date in mendelian predispositions to cancer.     

Effect of the codon 72 polymorphism (c.215G>C, p.Arg72Pro) in combination with somatic sequence variants in the TP53 gene on survival in patients with advanced ovarian carcinoma

This study was conducted to evaluate the frequency and prognostic impact of TP53 alterations stratified for the TP53 codon 72 polymorphism (c.215G>C, p.Arg72Pro) in a cohort of 109 patients with advanced ovarian carcinomas. TP53 sequence variants were observed in 80 of the 109 (73.4%) tumors and were significantly associated with grade of differentiation (P=0.001). A tendency towards higher frequency of sequence variants in tumors with higher FIGO stages was seen (P=0.05). The type of TP53 sequence variant (transition A:T>G:C vs. G:C>A:T at CpG dinucleotides, and transversion G:C>T:A) had significant correlation with patients' age (P=0.04) with more A:T>G:C in patients over 60 years old. No significant associations were found between frequency of sequence variants and age at diagnosis, histological type, size of residual tumor after primary surgery, or long-term survival. Analyses of the codon 72 polymorphism in tumor DNA gave a higher frequency of homozygosity/hemizygosity than expected from the population frequency, particularly for the Pro allele. Tumors homozygous or hemizygous for the Pro allele had significantly higher frequency of TP53 sequence variants, particularly of the nonmissense type (P=0.002), and patients with these types of alterations had significantly shorter survival (P=0.04). TP53 protein accumulation, determined by immunohistochemistry (IHC), was found in 67.9% (74 out of 109) of the tumors, was significantly more common among serous than nonserous ovarian carcinomas (P=0.008), and had a significant effect on progression-free survival (P=0.03). p63 (TP73L; formerly TP63) and p73 (TP73) protein accumulation detected by IHC was seen in 67.9 and 0% of the tumors, respectively. A significantly higher frequency of p63-positive cases was seen among serous tumors (P=0.008) and tended to increase with increasing FIGO stages (P=0.05), but had no significant effect on survival. No association between p63 protein accumulation and TP53 protein accumulation was seen.     

Association of genetic polymorphisms in MDM2, PTEN and P53 with risk of esophageal squamous cell carcinoma

Genetic variations in MDM2, PTEN and P53 might be involved in cancer susceptibility. To assess the contribution of polymorphisms in these three genes to the risk of esophageal squamous cell carcinoma (ESCC) in a Chinese population, we genotyped MDM2 T309G, Del1518, PTEN rs701848, rs2735343 and P53 Arg72Pro polymorphisms using PCR-restriction fragment length polymorphism analysis in 226 ESCC cases and 226 cancer-free controls. Here we showed that the risk of ESCC was elevated in subjects with any of the variant genotypes of PTEN rs2735343 and P53 Arg72Pro polymorphisms, but not any genotype of MDM2 or PTEN rs701848. Moreover, multiplicative interactions were observed between PTEN rs2735343 and P53 Arg72Pro or smoking status on risk of ESCC. Our study firstly indicated that PTEN rs2735343 might be a susceptibility factor for ESCC and reaffirmed the role of P53 Arg72Pro in ESCC in this Chinese population, but did not replicate the positive association between MDM2 T309G and ESCC found previously.     

TP53 mutations in astrocytic gliomas: an association with histological grade,TP53 codon 72 polymorphism and p53 expression

TP53 mutations and polymorphisms have been widely related to many cancers as long as these alterations may impair its capacity to induce cell cycle arrest, DNA repair mechanisms, and apoptosis. Although TP53 alterations have been studied in astrocytic tumors, there is a lack of analysis considering specific TP53 mutations and their associations with p53 immunostainning, polymorphisms and their significance among the histological grades. Thus, we analyzed TP53 alterations in exons 2–11, including the codon 72 polymorphism, using DNA sequencing in 96 astrocytic gliomas (18 grade I, 20 grade II, 14 grade III, and 44 grade IV). Also, immunohistochemistry was assessed to evaluate the p53 protein expression. In this study, we found that the higher histological grades were statistically associated with TP53 mutations. Some of these mutations, such as TP53 P98T and TP53 G244S, seemed to be a specific marker for the higher grades, and the TP53 E286K mutation appears to be a World Health Organization grade III–IV progression marker. Also, the TP53 P98T mutation, in exon 4, is very likely to be important on the stabilization of the p53 protein, leading to its immunopositivity and it is potentially associated with the TP53 72Pro/Pro genotype.     

p53 Codon 72 Genetic Polymorphism in Asthmatic Children: Evidence of Interaction With Acid Phosphatase Locus 1

Several lines of evidence are implicating an increased persistence of apoptotic cells in patients with asthma. This is largely due to a combination of inhibition, or defects in the apoptotic process and/or impaired apoptotic cell removal mechanisms. Among apoptosis-inducing genes, an important role is played by p53. In the present study, we have investigated the possible relationship between p53 codon 72 polymorphism and asthma and the interaction with ACP1, a genetic polymorphism involved in the susceptibility to allergic asthma. We studied 125 asthmatic children and 123 healthy subjects from the Caucasian population of Central Italy. p53 codon 72 and ACP1 polymorphisms were evaluated using a restriction fragment length polymorphism-polymerase chain reaction (RFLP-PCR) method. There is a statistically significant association between p53 codon 72 polymorphism and allergic asthma: Arg/Arg genotype is more represented in asthmatic patients than in controls (P=0.018). This association, however, is present in subjects with low ACP1 activity A/A and A/B only (P=0.023). The proportion of children with A/A and A/B genotype carrying Arg/Arg genotype is significantly high in asthmatic children than in controls (OR=1.941; 95% C.I. 1.042-3.628). Our finding could have important clinical implications since the subjects with A/A and A/B genotypes of ACP1 carrying Arg/Arg genotype are more susceptible to allergic asthma than Pro/Pro genotype.     

瘢痕疙瘩p53基因检测试剂盒的临床实验

目的:对瘢痕疙瘩p53基因检测试剂盒进行临床实验,评价此试剂盒的准确度和有效性。方法:运用聚合酶链反应-反向斑点杂交、DNA直接测序方法,检测52例临床瘢痕疙瘩患者和配对的52例正常人p53基因第72位密码子的基因型。结果:瘢痕疙瘩患者的Pro等位基因频率和Pro/Pro基因型频率明显高于对照组(χ2=6.268,P=0.018;χ2=11.34,P=0.01),而Pro/Arg型和Arg/Arg型未见有统计学差异。结论:p53基因第72位密码子Pro等位基因及Pro/Pro基因型是中国广东地区人群对瘢痕疙瘩的易感因素,瘢痕疙瘩p53基因检测试剂盒具有良好的可重复性和特异性。