p53 codon 72 polymorphism in basal cell carcinoma of the skin

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

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

Arg72Pro polymorphism of TP53 gene and the risk of skin cancer: a meta-analysis

Background

TP53 gene is one of the most important tumor suppressor genes. We undertook this meta-analysis to explore the association between TP53 Arg72Pro polymorphism and the risk of skin cancer mainly in Caucasians.

Methods

We searched PubMed for case-control studies published up to March 2013. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the strength of association.

Results

A total of 5276 skin cancer cases and 5315 controls from 20 studies were included. Overall, no significant association between TP53 Arg72Pro polymorphism and skin cancer was observed in all genetic contrast models (Pro/Pro versus Arg/Arg, Pro/Arg versus Arg/Arg, Pro/Pro + Pro/Arg versus Arg/Arg, Pro/Pro versus Arg/Arg + Pro/Arg, Pro allele versus Arg allele). Similar results were obtained in the stratified analysis by ethnicity and histological types of skin cancer, such as melanoma, squamous cell carcinoma and basal cell carcinoma. Power calculations indicated that some studies were underpowered. No publication bias was found by using the funnel plot and Egger's test.

Conclusions

This meta-analysis indicated that TP53 Arg72Pro polymorphism probably had little association with skin cancer susceptibility mainly in Caucasians. However, larger sample-size studies are required to verify the conclusion as low statistical powers.

The association between TP53 Arg72pro polymorphism and non-melanoma skin cancer risk: a meta-analysis including 7,107 subjects

Background:

The p53 gene is a critical molecular in the protection of cells from DNA damage due to Ultraviolet (UV) exposure, and TP53 mutation is very common in non-melanoma skin cancer.

Objectives:

To assess the association between the TP53 Arg72Pro polymorphism and non-melanoma skin cancer (NMSC) risk.

Methods:

We performed this meta–analysis with 13 case-control studies involving 3,520 cases and 3,587 controls.

Results:

Our meta-analysis showed that TP53 Arg72Pro polymorphism was not associated with non-melanoma skin cancer susceptibility in overall population.(for Arg/Arg vs. Pro/Pro: OR 0.98, 95% CI 0.80-1.19; for Arg/Pro vs. Pro/Pro: OR 0.99, 95% CI 0.84-1.17; for the recessive model Arg/Arg vs. Arg/Pro + Pro/Pro: OR 1.10, 95% CI 0.89-1.35; for the dominant model Arg/Arg + Arg/Pro vs. Pro/Pro: OR 1.00, 95% CI 0.85-1.18). We also detected no effect of this polymorphism on any subtype of non-melanoma skin cancer, such as squamous cell carcinoma (SCC), and basal cell carcinoma (BCC). Furthermore, no significant association in any subgroup was detected in stratified analyses according to ethnicity. However, in the stratified analysis by sample collection resources, Arg/Arg carriers from tumor tissue subgroup had 3.42 times risk of cancer (95% CI, 1.19 to 9.84) as compared with the variant type Pro/Pro in NMSC.

Conclusions:

TP53 Arg72Pro polymorphism may have little involvement in the pathogenesis of NMSC, regardless of type, including SCC, and BCC.

TP53 codon 72 polymorphism in pigmentary phenotypes

The p53 protein exerts different cellular functions, and recent findings have demonstrated its influence on the cascade of skin pigmentation during UV exposure. Among TP53 gene polymorphisms, the most studied is the G to C transversion in exon 4 at codon 72, which results in three distinct genotypes, Arg/Arg, Pro/Pro and Arg/Pro, each one encoding different p53 isoforms. Therefore, this study aimed to determine the relationship between TP53 codon 72 polymorphism and skin protection against sunburn. Genomic DNA was extracted from peripheral blood samples and genotyping was performed by PCR and confirmed by restriction enzyme digestion. The genotype frequency was 50% for Arg/Arg and 14.6% for Pro/Pro genotype. The frequency of heterozygous subjects was 35.4%. In our population, p53 genotypes were in Hardy-Weinberg (HW) equilibrium (X2 HM less than 3.84), showing a predominance of arginine allele (total Arg allele frequency of 68%). No significant association between p53 genotype and skin colour, hair or eye colour and susceptibility to sun exposure was found. However, further analysis demonstrated a significant association between the genotype Pro/Pro and blue/green eyes among participants who presented redness (P=0.016). Our findings indicate susceptibility to sun exposure when this phenotype (eye colour) occurs simultaneously with Pro/Pro genotype.

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

The TP53 gene has an important role in the protection of cells from DNA damage due to UV exposure, and sequence variation in the gene may alter skin cancer susceptibility. To examine the association between the TP53 Arg72Pro polymorphism and skin cancer risk, we undertook a meta-analysis of 15 case-control studies involving 6,362 subjects. The quality of the studies was assessed according to a predefined scale. Crude odds ratios (ORs) with 95% confidence intervals (CIs) were assessed for association using a random-effects model. Overall, no evidence of association was observed between TP53 genotypes and the risk of skin cancer in any genetic model (Arg/Arg vs. Pro/Pro: OR=1.05, 95% CI: 0.71-1.55; Arg/Pro vs. Pro/Pro: OR=0.92, 95% CI: 0.68-1.24; Arg/Arg+Arg/Pro vs. Pro/Pro: OR=0.97, 95% CI: 0.70-1.35; Arg/Arg vs. Arg/Pro+Pro/Pro: OR=1.15, 95% CI: 0.91-1.46). Stratified analyses according to ethnicity and quality score of the studies also detected no significant association in any subgroup. Furthermore, no effect of this polymorphism on subtype of skin cancer, such as melanoma, squamous cell carcinoma, and basal cell carcinoma, was observed. In conclusion, this meta-analysis suggests that the TP53 Arg72Pro polymorphism may have little involvement in skin cancer susceptibility.

Manganese superoxide dismutase vs. p53: regulation of mitochondrial ROS

Coordination of mitochondrial and nuclear activities is vital for cellular homeostasis, and many signaling molecules and transcription factors are regulated by mitochondria-derived reactive oxygen species (ROS) to carry out this interorganellar communication. The tumor suppressor p53 regulates myriad cellular functions through transcription-dependent and -independent mechanisms at both the nucleus and mitochondria. p53 affect mitochondrial ROS production, in part, by regulating the expression of the mitochondrial antioxidant enzyme manganese superoxide dismutase (MnSOD). Recent evidence suggests mitochondrial regulation of p53 activity through mechanisms that affect ROS production, and a breakdown of communication amongst mitochondria, p53, and the nucleus can have broad implications in disease development.

Study of p53 codon 72 polymorphism and codon 249 mutations in Southern India in relation to age, alcohol drinking and smoking habits

Germline polymorphisms of genes involved in different steps of tumorigenesis like p53, the tumor suppressor gene, are reported to determine the individual susceptibility to cancer. Lung cancer is one of the most common and lethal cancers and tobacco smoking remains its most important etiologic factors. The most frequently p53 mutated codons of lung cancer are 72 (exon 4) and 249 (exon 7). Since mutations in the p53 gene are present in ∼40% of all human lung cancers and are more common in smokers than in nonsmokers, we aimed to detect the status of p53 at codon 72 for Arg/Arg or Arg/Pro or Pro/Pro allele polymorphism and p53 codon 249 mutation in smokers and nonsmokers of South India. Allele frequencies in the nonsmokers were 0.16 for the Arg/Pro allele and 0.84 for the Pro/Pro allele in our study population. Among the smokers, the frequencies of the Arg/Pro, Arg/Arg, and Pro/Pro alleles were 0.88, 0.04, and 0.08, respectively. No mutation was detected in both smokers and nonsmokers in p53 codon 249. From the worldwide scenario, it can be speculated that the smokers, with Arg/Pro genotype are more prone for lung cancer or to other types of cancer.

Watching the watcher: regulation of p53 by mitochondria

p53 has been referred to as the 'guardian of the genome' because of its role in protecting the cell from DNA damage. p53 performs its duties by regulating cell-cycle progression and DNA repair and, in cases of irreparable DNA damage, by executing programmed cell death. Mitochondria are an important target of transcription-dependent and -independent actions of p53 to carry out the apoptotic function. However, increasing evidence suggests that p53 activity is regulated by mitochondria. Cellular insults that alter mitochondrial function can have important consequences on p53 activity. In light of these new findings, the following review focuses on p53/mitochondria connections, in particular how reactive oxygen species generated at mitochondria regulate p53 activity. A better understanding of the mechanisms by which mitochondria regulate p53 may have an impact on our understanding of the development and progression of many diseases, especially cancer.

p53 codon 72 polymorphism, DNA damage and repair, and risk of non-melanoma skin cancer

A very common polymorphism of p53, that of codon 72, codes either for a proline (P72) or an arginine (R72). The two alleles differ in their biological properties: P72 is a stronger inducer of p21, while R72 induces 5-10 times more apoptosis. It is not known, however, whether this polymorphism influences genome stability. The influence of p53 codon 72 polymorphism on cancer risk has been studied for different types of cancer with mixed and inconsistent results. With respect to sporadic non-melanoma skin cancer (NMSC), there are few studies, with small sample sizes, and none in a Latinoamerican population. These studies have found no association between p53 genotype at codon 72 and NMSC. We analyzed whether p53 codon 72 genotype influences genomic stability and the sensitivity of cells to UVB. We also carried out a case-control study of NMSC in a Mexican population which included 204 BCC cases, 42 SCC cases, and 238 controls. There was no association between p53 genotype and basal levels of DNA damage, oxidative DNA damage sensitivity, or DNA repair capacity. R72 dominantly increased the in vitro sensitivity of cells to UVB-induced apoptosis. There was no significant association either between p53 genotype and basal cell carcinoma (BCC), squamous cell carcinoma (SCC) or both combined.