Polymorphisms in the p53 pathway

The TP53 Arg72Pro polymorphism predicts visual and neurodegenerative outcomes in retinal detachment

Retinal detachment (RD) separates the retina from the retinal epithelium, causing photoreceptor apoptosis and irreversible vision loss. Even with successful surgical reattachment, complete visual recovery is not guaranteed. The TP53 Arg72Pro polymorphism, implicated in apoptosis, has emerged as a potential predictor of RD outcomes. We investigated the impact of the Arg72Pro polymorphism on retinal neurodegeneration and functional recovery in patients. The underlying mechanisms were analyzed in a humanized TP53 Arg72Pro RD mouse model. In a cohort of 180 patients, carriers of the Pro allele exhibited decreased apoptotic gene expression and improved visual recovery. Complementary findings in mice revealed that the Pro variant preserved photoreceptor integrity and reduced apoptosis rates following RD. Our findings highlight the potential of this TP53 polymorphism as a biomarker for RD outcomes and a tool for tailoring therapies. This study underscores the importance of integrating genetic profiling into personalized medicine approaches to improve recovery of RD patients' visual outcomes.

Proline-Selective Electrochemiluminescence Detecting a Single Amino Acid Variation Between A1 and A2 β-Casein Containing Milks

The proline amino acid and prolyl residues of peptides/proteins confer unique biological and biochemical properties that motivates the development of proline-selective analysis. The study focuses on one specific class of problem, the detection of single amino acid variants involving proline, and reports a Pro-selective electrochemiluminescence (ECL) method. To develop this method, the A1-/A2- variants of milk's β-casein protein are investigated because it is a well-established example and abundant samples are readily available. Specifically, β-casein has 209 amino acids with 34 (or 35) proline residues: the A1-variant has a Pro-to-His substitution at position 67 (relative to the A2 variant). The study shows that proline's strong luminescence allows the generic discrimination of: Pro from other amino acids; an A2-oligopeptide from an A1-oligopeptide; the A2-β-casein variant from the A1-variant; and commercially-available A2 milks from A1-containing regular milks. The evidence indicates that luminescence depends on proline content and accessibility, as well as signal quenching. Compared to conventional immunoassays, the ECL method is simple, rapid, and inexpensive. Further, the ECL-method is Pro-selective (vs molecularly-selective like typical immunoassays) which should make it broadly useful for studying the role of proline in biology and especially useful for tracking the digestion of proline-rich proteins in the diet.

Understanding genetic variations associated with familial breast cancer

BACKGROUND

Breast cancer is the most frequent cancer among women. Genetics are the main risk factor for breast cancer. Statistics show that 15-25% of breast cancers are inherited among those with cancer-prone relatives. BRCA1, BRCA2, TP53, CDH1, PTEN, and STK11 are the most frequent genes for familial breast cancer, which occurs 80% of the time. In rare situations, moderate-penetrance gene mutations such CHEK2, BRIP1, ATM, and PALB2 contribute 2-3%.

METHODS

A search of the PubMed database was carried out spanning from 2005 to July 2024, yielding a total of 768 articles that delve into the realm of familial breast cancer, concerning genes and genetic syndromes. After exclusion 150 articles were included in the final review.

RESULTS

We report on a set of 20 familial breast cancer -associated genes into high, moderate, and low penetrance levels. Additionally, 10 genetic disorders were found to be linked with familial breast cancer.

CONCLUSION

Familial breast cancer has been linked to several genetic diseases and mutations, according to studies. Screening for genetic disorders is recommended by National Comprehensive Cancer Network recommendations. Evaluation of breast cancer candidate variations and risk loci may improve individual risk assessment. Only high- and moderate-risk gene variations have clinical guidelines, whereas low-risk gene variants require additional investigation. With increasing use of NGS technology, more linkage with rare genes is being discovered.

A Missense Variant in TP53 Could Be a Genetic Biomarker Associated with Bone Tissue Alterations

Metabolic bone diseases cover a broad spectrum of disorders that share alterations in bone metabolism that lead to a defective skeleton, which is associated with increasing morbidity, disability, and mortality. There is a close connection between the etiology of metabolic bone diseases and genetic factors, with TP53 being one of the genes associated therewith. The single nucleotide polymorphism (SNP) Arg72Pro of TP53 is a genetic factor associated with several pathologies, including cancer, stroke, and osteoporosis. Here, we aim to analyze the influence of the TP53 Arg72Pro SNP on bone mass in humanized Tp53 Arg72Pro knock-in mice. This work reports on the influence of the TP53 Arg72Pro polymorphism in bone microarchitecture, OPG expression, and apoptosis bone status. The results show that the proline variant of the TP53 Arg72Pro polymorphism (Pro72-p53) is associated with deteriorated bone tissue, lower OPG/RANK ratio, and lower apoptosis in bone tissue. In conclusion, the TP53 Arg72Pro polymorphism modulates bone microarchitecture and may be a genetic biomarker that can be used to identify individuals with an increased risk of suffering metabolic bone alterations.

Prevalence of TP53 gene Pro72Arg (rs1042522) single nucleotide polymorphism among Egyptian breast cancer patients

Background

The P53 protein has an essential role in several cellular processes, including DNA repair, apoptosis, and cell cycle arrest. The pathophysiology of many cancer types has frequently been linked to polymorphisms in the TP53 locus. Over 200 single nucleotide polymorphisms (SNPs) have been identified in TP53. However, Pro72Arg (rs1042522) at codon 72, shows contradictory results in terms of cancer risk. In this study, we aimed to determine if the Pro72Arg (rs1042522) SNP in the TP53 gene would be linked to breast cancer (BC) risk among Egyptian patients.

Materials and Methods

Genomic DNA was extracted from blood samples of 100 healthy volunteers and 100 breast cancer patients (50 familial and 50 non-familial). TP53 Genotyping was performed using tetra-primer amplification refractory mutation (Tetra-ARMS) PCR. Data were analyzed using SNPstat software.

Results

The prevalence of TP53 (Pro72Arg) rs1042522 genotypes carrying the high-risk allele [Pro/Arg (CG) and Arg/Arg (GG)] were significantly higher in BC patients compared to healthy volunteers and were associated with BC susceptibility (OR 0.2; [95% CI 0.11–0.38]; P = 0.0001). However, there was no statistical significant difference in the prevalence of TP53 (Pro72Arg) rs1042522 genotypes carrying the high-risk allele between familial and non-familial BC patients. In addition, there was no association between the prevalence of TP53 (Pro72Arg) rs1042522 genotypes carrying the high-risk allele and BC patients’ clinical and pathological characteristics including tumor size, tumor grade, lymph node status, presence of lymphovascular invasion, expression of ER, PR and Her-2 in both of familial and non-familial BC patients.

Conclusions

TP53 (Pro72Arg) rs1042522 is more prevalent among BC patients but not associated with disease progression.

Association of LDLR, TP53 and MMP9 Gene Polymorphisms With Atherosclerosis in a Malaysian Study Population

Preliminary research has shown that low density lipoprotein receptor (LDLR), tumor protein (TP53) and matrix metalloproteinase 9 (MMP9) genes expression levels were significantly increased in atherosclerosis coronary artery tissue (ACAT) compared to non-atherosclerotic coronary artery tissue (NCAT) samples. Thus, further investigation was carried out to study the association of LDLR, TP53 and MMP9 gene polymorphisms and the risk of developing atherosclerosis (ATH) in a Malaysian population. Single nucleotide polymorphisms of C88S, TP53 codon 72 and MMP9C>T were analyzed in 76 ACAT samples and 149 NCAT samples, representing cases and controls, respectively. In results, heterozygous CT genotype of MMP9C>T polymorphism was significantly higher in ACAT compared to NCAT samples (57.9% vs 27.5%, χ² = 19.758, df= 1, P < 0.05). The CT genotype was found to be significantly associated with the risk of developing ATH (OR = 3.622, 95% CI = 2.028-6.470). However, the distribution of the CT genotype in a healthy Malaysian study population was incomparable regardless of gender and ethnicity. The DNA sequencing results validated the C88S, TP53 codon 72, and MMP9C>T polymorphisms. In conclusion, the CT genotype of the MMP9-1562C>T polymorphism was found to have a strong association with the risk of developing ATH.

Central Nervous System Tissue Regeneration after Intracerebral Hemorrhage: The Next Frontier

Despite marked advances in surgical techniques and understanding of secondary brain injury mechanisms, the prognosis of intracerebral hemorrhage (ICH) remains devastating. Harnessing and promoting the regenerative potential of the central nervous system may improve the outcomes of patients with hemorrhagic stroke, but approaches are still in their infancy. In this review, we discuss the regenerative phenomena occurring in animal models and human ICH, provide results related to cellular and molecular mechanisms of the repair process including by microglia, and review potential methods to promote tissue regeneration in ICH. We aim to stimulate research involving tissue restoration after ICH.

Interactions among variants in P53 apoptotic pathway genes are associated with neurologic deterioration and functional outcome after acute ischemic stroke

OBJECTIVE

Neurologic deterioration (ND) and functional outcome after ischemic stroke (IS) are not accurately predicted by clinical pictures on admission. The aim of present study was to investigate the association of variants in P53 apoptotic pathway genes with ND and functional outcome after IS.

METHODS

Genotypes of nine variants in apoptosis-relevant genes were measured in patients with acute IS. Gene-gene interactions were analyzed by generalized multifactor dimensionality reduction (GMDR). The primary outcome was ND. ND was diagnosed in patients who worsened ≥2 points (National Institutes of Health Stroke Scale [NIHSS] score) within the first 10 days of stroke onset. The secondary outcome was functional status at 90 days after IS as measured by modified Rankin Scale (mRS) score.

RESULTS

A total of 705 enrolled patients, ND occurred in 174 (24.7%) patients, and 184 (26.1%) patients were poor functional outcome (mRS score > 2). Although the nine variants were not significantly associated with ND and functional outcome by univariate analysis, there was a gene-gene interaction among P53rs1042522, MDM-2rs2279744, and MMP-9 rs3918242 using GMDR analysis. The high-risk interaction among the three variants was independently associated with higher risk of ND (HR, 2.04, 95% CI: 1.22-5.64, p = .018) and poor functional outcome (OR, 2.68, 95% CI: 1.68-7.86, p = .004) after adjusting for the covariates.

CONCLUSION

The interactions among P53 rs1042522, MDM-2 rs2279744, and MMP-9 rs3918242 may increase the risk of ND and poor functional outcome and may be considered as a genetic marker of predicting ND and poor functional outcome after stroke.

Anti-tumor activities of Panax quinquefolius saponins and potential biomarkers in prostate cancer

BACKGROUND

Prostate carcinoma is the second most common cancer among men worldwide. Developing new therapeutic approaches and diagnostic biomarkers for prostate cancer (PC) is a significant need. The Chinese herbal medicine Panax quinquefolius saponins (PQS) have been reported to show anti-tumor effects. We hypothesized that PQS exhibits anti-cancer activity in human PC cells and we aimed to search for novel biomarkers allowing early diagnosis of PC.

METHODS

We used the human PC cell line DU145 and the prostate epithelial cell line PNT2 to perform cell viability assays, flow cytometric analysis of the cell cycle, and FACS-based apoptosis assays. Microarray-based gene expression analysis was used to display specific gene expression patterns and to search for novel biomarkers. Western blot and quantitative real-time PCR were performed to demonstrate the expression levels of multiple cancer-related genes.

RESULTS

Our data showed that PQS inhibited the viability of DU145 cells and induced cell cycle arrest at the G1 phase. A significant decrease in DU145 cell invasion and migration were observed after 24 h treatment by PQS. PQS up-regulated the expression levels of p21, p53, TMEM79, ACOXL, ETV5, and SPINT1 while it down-regulated the expression levels of bcl2, STAT3, FANCD2, DRD2, and TMPRSS2.

CONCLUSION

PQS promoted cells apoptosis and inhibited the proliferation of DU145 cells, which suggests that PQS may be effective for treating PC. TMEM79 and ACOXL were expressed significantly higher in PNT2 than in DU145 cells and could be novel biomarker candidates for PC diagnosis.

Genetic variants and risk of thyroid cancer among Iranian patients

The definition of an exclusive panel of genetic markers is of high importance to initially detect among this review population. Therefore, we gave a summary of each main genetic marker among Iranian patients with thyroid cancer for the first time which were classified based on their cellular function. Due to the results, a significant relationship was found between SNP in codons 194, 280, and 399 (XRCC1), Allele 3434Thr (XRCC7), GC or CC genotype 31, G/C (Survivin), 399G>A (XRCC1), Tru9I (vitamin D receptor), G-D haplotype (MDM2), TT genotype, -656 G/T (IL-18), TAGTT haplotype (IL-18), G allele in +49 A>G (CTLA-4), +7146 G/A (PD-1.3), +7785 C/T (PD-1.5), rs1143770 (let7a-2), rs4938723 (pri-mir-34b/c) genes, and thyroid cancers. Moreover, SNP in 677C-->T (MTHFR), GG genotype Asp1312Gly (thyroglobulin), 2259C>T (Rad52), R188H, (XRCC2), T241M (XRCC3) had higher risks of thyroid cancer and lower risks were observed in -16 Ins-Pro (p53), rs3742330 (DICER1). At last, the protective effects were explored in 127 CC genotype (IL-18), rs6877842 (DROSHA). Conduct further studies on the types of DNA repair gene polymorphisms with a larger number in the thyroid cancer using modern methods such as SNP array so that these genes could be used as a biomarker in prediction, diagnosis, and treatment of thyroid cancer. This review presents for the first time a summary of important genetic markers in Iranian patients with thyroid cancer.

Association Between Arg72Pro Polymorphism in TP53 and Malignant Abdominal Solid Tumor Risk in Hunan Children

Pediatric solid tumors are heterogeneous and comprise various histological subtypes. TP53, a tumor suppressor, orchestrates the transcriptional activation of anti-cancer genes. The gene coding for this protein is highly polymorphic, and its mutations are associated with cancer development. The Arg72Pro polymorphism in TP53 has been associated with susceptibility to various types of cancer. Here, in this hospital-based study, we evaluated the association of this polymorphism with susceptibility toward malignant abdominal solid tumors in children in the Hunan province of China. We enrolled 162 patients with neuroblastoma, 60 patients with Wilms' tumor, and 28 patients with hepatoblastoma as well as 270 controls. Genotypes were determined using a TaqMan assay, and the strength of the association was assessed using an odds ratio, within a 95% confidence interval identified using logistic regression models. Our results showed that the Arg72Pro polymorphism did not exhibit significant association with susceptibility toward pediatric malignant abdominal solid tumors. Stratification analysis revealed that this polymorphism exerts weak sex- and age-specific effects on Wilms' tumor and hepatoblastoma susceptibility, respectively. Overall, our results indicate that the Arg72Pro polymorphism may have a marginal effect on susceptibility toward pediatric malignant abdominal solid tumors in Hunan, and this finding warrants further confirmation.

B-MYB-p53-related relevant regulator for the progression of clear cell renal cell carcinoma

PURPOSE

To investigate the mRNA expression of B-MYB and MDM2 together with their p53 relatedness in clear cell renal cell carcinoma (ccRCC).

METHODS

Genes were screened for their mRNA expression from 529 patients in a publicly available ccRCC cohort (TCGA). A cohort of 101 patients with ccRCC served as validation by qRT-PCR mRNA tissue expression analysis.

RESULTS

Expression: B-MYB expression was significantly higher in high-grade tumours (p < 0.0001 and p = 0.048) and in advanced stages (p = 0.005 and p = 0.037) in both cohorts. Correlation: p53-B-MYB as well as MDM2-B-MYB showed significant correlations in local and low-grade ccRCCs, but not in high grade tumours or advanced stages (r < 0.3 and/or p > 0.05). Survival: Multivariable Cox regression of the TCGA cohort revealed B-MYB upregulation and low MDM2 expression as predictors for an impaired overall survival (OS) (HR 1.97; p = 0.0003; HR 2.94, p < 0.0001) and progression-free survival (PFS) (HR 2.86; p = 0.0005; HR 1.58, p = 0.046). In the validation cohort, the results were confirmed for OS by univariable, but not multivariable regression: high B-MYB expression (HR = 3.05, p = 0.035) and low MDM2 expression (HR 3.81, p value 0.036).

CONCLUSION

In ccRCC patients with high-grade tumours and advanced stages, high B-MYB expression is common and is associated with poorer OS and PFS. These patients show a loss of their physiological B-MYB-p53 network correlation, suggesting an additional, alternative regulatory, oncogenic mechanism. Assuming further characterization of its signalling pathways, B-MYB could be a potential therapy target for ccRCC.

TP53 rs1042522 polymorphism and early-onset breast cancer

Background:

Breast cancer is the leading cause of cancer deaths among women. Early-onset breast cancer is well recognized as it clinically differs from old-age diagnosed breast neoplasms. TP53 rs1042522 polymorphism relates to the risk of breast neoplasms, but this relationship in Turkish early-onset breast cancer patients has not been investigated yet. We aimed to search the relationship between TP53 rs1042522 polymorphism and young Turkish breast cancer patients.

Materials and Methods:

Ninety-six female breast cancer patients who were ≤ 40 years of age and 96 healthy controls were enrolled in our study. Participants were genotyped by the hybridization probe system.

Results:

We identified that the genotype frequencies of rs1042522 were significantly different between controls and cases (P = 0.027). Participants carrying CG genotype had also reduced breast cancer risk (odds ratio = 0.4196, 95% confidence interval: 0.1941–0.9067, P = 0.027). Our results revealed that there is an association between GG and CG + CC genotype groups with progesterone receptor (PgR) status (P = 0.0219).

Conclusion:

Our findings indicate that the CG genotype is a protective factor against breast neoplasms. No other clinicopathologic parameters except for PgR status were found to be related to rs1042522 polymorphism in young Turkish breast cancer patients.

Genetic polymorphisms of TP53 Arg72Pro and Pro47Ser among Egyptian patients with colorectal carcinoma

BACKGROUND

Previous reports demonstrated the role of TP53 gene polymorphisms with CRC risk among several ethnic populations. The purpose of this study is to assess the association of the TP53 Arg72Pro and Pro47Ser variants with CRC risk among Egyptian patients.

SUBJECTS AND METHODS

This work was conducted on 120 unrelated CRC Egyptian patients who were compared to 140 healthy controls. DNA was genotyped for these variants using the PCR-RFLP technique.

RESULTS

CRC patients observed a significant association of the rare genotype of TP53 Arg72Pro polymorphism compared with healthy controls. On the contrast, all genetic models showed no statistical association of TP53 Pro47Ser polymorphism among CRC patients compared with healthy controls. On the contrast, CRC patients of the TP53 gene polymorphisms indicated no significant difference regarding their clinical and laboratory markers.

CONCLUSIONS

Our findings indicate a strong association with TP53 Arg72Pro variant within increased risk of CRC among Egyptian patients.

Association of the TP53 rs1042522 C>G polymorphism and hepatoblastoma risk in Chinese children

The TP53 gene encodes an important class of cell cycle and tumor-suppressing factors that play critical roles in maintaining genomic stability. The TP53 Arg72Pro (rs1042522 C>G) polymorphism has been reported to be associated with the risk of several types of adult cancers; however, its risk for pediatric cancers remains unclear. Here, we analyzed the association of the TP53 gene rs1042522 C>G polymorphism with hepatoblastoma (HB) susceptibility in a hospital-based study among Chinese children. A total of 213 HB patients and 958 healthy controls were enrolled in the study. Genotypes were determined by a TaqMan assay, and the strength of the association was assessed by the odds ratios and 95% confidence intervals generated from logistic regression models, adjusted for age, gender, and clinical stage. No significant association between the TP53 rs1042522 C>G polymorphism and HB susceptibility was detected in the main analysis or in stratification analyses of age, gender, and clinical stages. Overall, the TP53 gene rs1042522 C>G polymorphism is not associated with HB susceptibility in the Chinese population, other polymorphisms alone or in combination should be investigated to further clarify HB susceptibility.

Association of Single-Nucleotide Polymorphisms in Monoubiquitinated FANCD2-DNA Damage Repair Pathway Genes With Breast Cancer in the Chinese Population

Objective:

The aim of the study was to estimate breast cancer risk conferred by individual single-nucleotide polymorphisms of breast cancer susceptibility genes.

Methods:

We analyzed the 48 tagging single-nucleotide polymorphisms of 8 breast cancer susceptibility genes involved in the monoubiquitinated FANCD2–DNA damage repair pathway in 734 Chinese women with breast cancer and 672 age-matched healthy controls.

Results:

Forty-five tagging single-nucleotide polymorphisms were successfully genotyped by SNPscan, and the call rates for each tagging single-nucleotide polymorphisms were above 98.9%. We found that 13 tagging single-nucleotide polymorphisms of 5 genes (Parter and localizer of Breast cancer gene2 (PALB2), Tumour protein 53 (TP53), Nijmegen breakage syndrome 1, Phosphatase and tensin homolog deleted from chromosome 10 (PTEN), and Breast cancer gene 1 (BRCA1-interacting protein 1)) were significantly associated with breast cancer risk. A total of 5 tagging single-nucleotide polymorphisms (rs2299941 of PTEN, rs2735385, rs6999227, rs1805812, and rs1061302 of Nijmegen breakage syndrome 1) were tightly associated with breast cancer risk in sporadic cases, and 5 other tagging single-nucleotide polymorphisms (rs1042522 of TP53, rs2735343 of PTEN, rs7220719, rs16945628, and rs11871753 of BRCA1-interacting protein 1) were tightly associated with breast cancer risk in familial and early-onset cases.

Conclusions:

Some of the tagging single-nucleotide polymorphisms of 5 genes (PALB2, TP53, Nijmegen breakage syndrome 1, PTEN, and BRCA1-interacting protein 1) involved in the monoubiquitinated FANCD2–DNA damage repair pathway were significantly associated with breast cancer risk.

The combined survival effect of codon 72 polymorphisms and p53 somatic mutations in breast cancer depends on race and molecular subtype

BACKGROUND

The codon 72 polymorphism in the p53 gene relates to the risk of breast cancer (BC), but this relationship in racially diverse populations is not known. The present study examined the prognostic value of this polymorphism for African American (AA) and Caucasian (CA) BC patients separately and considered the confounding variables of molecular subtypes and somatic mutations in p53.

METHODS

Tissue sections of BCs from 116 AAs and 160 CAs were evaluated for p53 mutations and genotyped for the codon 72 polymorphism. The relationships of phenotypes to clinicopathologic features were determined by χ2 analyses; patient survival was estimated by Kaplan-Meier univariate and Cox regression multivariate models in a retrospective cohort study design.

RESULTS

The proportion of single nucleotide polymorphism (SNP) 72 alleles differed for races. Many cancers of AAs were Pro/Pro, but most for CAs were Arg/Arg. A higher frequency of missense p53 mutations was evident for AAs. There was an interaction between the SNP allele and p53 mutations for AA women only. The proportion of women with both the Pro/Pro allele and a p53 somatic mutation was higher for AA than CA women. The interaction between missense p53 mutations and Pro/Pro had a negative effect on survival, particularly for AAs with luminal cancers.

CONCLUSIONS

For BCs, the survival effect of SNP72 combined with a p53 missense mutation is dependent on race and molecular subtype. Although such a mutation is a marker of poor prognosis, it is relevant to identify the variant Pro/Pro in the case of AAs, especially those with luminal subtypes of BC.

TP53 rs1042522 C>G polymorphism and Wilms tumor susceptibility in Chinese children: a four-center case-control study

Wilms tumor is the most common renal malignancy that occurs in children. TP53 gene is considered as a tumor-suppressing gene through controlling cell growth. TP53 gene rs1042522 C>G (Arg72Pro) polymorphism is widely investigated in various types of cancers. However, it is not established if TP53 rs1042522 C>G polymorphism is a candidate variant for Wilms tumor risk. The aim of the study was to determine whether TP53 rs1042522 C>G polymorphism is responsible for the risk of Wilms tumor in Chinese children. All subjects (355 cases and 1070 controls) from four centers of China were genotyped for rs1042522 C>G polymorphism. The effect of rs1042522 C>G polymorphism on Wilms tumor prevalence was analyzed using logistic regression models. We failed to detect a significant relationship between rs1042522 C>G polymorphism and Wilms tumor risk. Further stratification analysis also could not detect a significant relationship. We conclude that TP53 rs1042522 C>G polymorphism might not have enough impact on the risk of Wilms tumor. More validation study with larger sample size will be required to better define the role of TP53 rs1042522 C>G polymorphism in Wilms tumor risk.

Impact of p53 arg72pro SNP on Breast Cancer Risk in North Indian Population

Background:

Genetic changes in p53 gene contribute to breast cancer susceptibility.

Objective and Methods:

A case-control study and a meta-analysis were performed to investigate the role of p53 codon72 SNP with breast cancer susceptibility in Indian women.

Results:

p53 heterozygous arginine variant was associated with decreased risk of breast cancer in total cohort. In meta-analysis, Allelic and GG vs. CC genetic comparison model were found to be associated with breast cancer risk. Moreover, recessive comparison model indicated a protective correlation with breast cancer occurrence.

Conclusion:

The findings of our case-control study and meta-analysis suggest a significant association between p53 Arg72Pro polymorphism and an increased risk of breast cancer in Indian population.

TP53 Arg72Pro polymorphism is associated with increased overall survival but not response to therapy in Portuguese/Caucasian patients with advanced cervical cancer

Identification of mechanisms that influence the therapeutic response and survival in patients with cancer is important. It is known that the genetic variability of the host, including presence of genetic polymorphisms in genes involved in DNA damage response, serves a crucial role in the prognosis of these patients. The present hospital-based retrospective cohort study aimed to evaluate the influence of TP53 Arg72Pro (rs1042522) polymorphism in the clinical outcome of 260 Caucasian patients diagnosed with cervical cancer and treated with concomitant radiotherapy and chemotherapy. The polymorphism genotyping was assessed using allelic discrimination by quantiative polymerase chain reaction. The results indicate that the TP53 Arg72Pro polymorphism did not significantly impact the response to therapy (P=0.571) nor disease-free survival (P=0.081). However, the polymorphism did influence overall survival, as increased median survival time was observed for patients carrying Arg/Pro genotype when compared with patients with Arg/Arg and Pro/Pro genotypes (126 months vs. 111 months, respectively; P=0.047). To conclude, the present findings suggest that a pharmacogenomic profile based on the genetic background of patients, including the analysis of the TP53 genotypes, may individualize treatment nad assist in the selection of therapies that may improve clinical outcome and lower toxicity for the patients.

Esophageal cancer research today and tomorrow: Lessons from algae and other perspectives

Esophageal cancer is an increasing concern due to poor prognosis, aggressive disease modalities, and a lack of efficient therapeutics. The two types of esophageal cancer: esophageal squamous cell carcinoma (ESCC) and esophageal adenocarcinoma (EAC) are responsible for an estimated 450,000 annual deaths, with over 457,000 new patients diagnosed in 2015, making it the eighth most prevalent and the 10th most fatal cancer worldwide. As esophageal cancer prevalence continues to increase, and so does the pressing need for the development of new and effective strategies for the early diagnostics, prevention, and treatment of this cancer, as well for building the innovative research tools to understand the affected molecular mechanisms. This short review summarizes the current statistics and recent research of the problems and solutions related to the esophageal cancer, and offer a brief overview of its epidemiology, molecular alterations, and existing biomedical tools. We will discuss currently available research tools and discuss selected approaches we deem relevant to find new model systems and therapies for the future with the special focus on novel opportunities presented by the unique molecules found in algae, namely carbohydrates and lipids. Their remarkable chemical variability is connected to their striking structural and functional properties, which combined with the relative novelty of these compounds to cancer biology, warrants interest of the wide biomedical community to these molecules, especially in the esophageal cancer theory and practice.

TP53 codon 72 polymorphism may predict early tumour progression in paediatric pilocytic astrocytoma

Pilocytic astrocytoma and ganglioglioma may occur in inaccessible or surgically difficult areas. In case of incomplete resection, the availability of biological predictors of tumour progression could be particularly important. To this end, an analysis of p53 codon 72 polymorphism and assessment of its role as prognostic marker were performed.

The status of the p53 Arg72Pro polymorphism was evaluated by pyrosequencing method in a multicenter cohort of 170 paediatric patients. Genotype/phenotype associations were investigated either by means of bivariate or multivariate analyses.

In the partially resected pilocytic astrocytomas, the Arg/Arg variant predicts early tumour progression (median survival time: 23.1 months) and is associated with poor event-free survival (p value = 0.0009). This finding remains true also in case of adjuvant therapies, with a 5-year event-free survival of 30.6% for cases with Arg/Arg variant vs. 78.7% for those with other genotypes. There is no association between ganglioglioma and the polymorphism.

The assessment of Arg/Arg variant could improve the management of pilocytic astrocytoma. TP53 codon 72 analysis could distinguish low-risk cases, in which surgery could be conservative, from high-risk cases needing an aggressive surgery plan.

Lack of evidence of HPV etiology of prostate cancer following radical surgery and higher frequency of the Arg/Pro genotype in Turkish men with prostate cancer

Objectives

The aim of this study was to assess the possible role of HPV in the development of prostate cancer (PCa) and investigate the distribution of the p53 codon 72 polymorphism in PCa in a Turkish population.

Materials and methods

A total of 96 tissues, which had been obtained using a radical surgery method, formalin-fixed and parafin-embedded, were used in this study. The study group consisted of 60 PCa tissues (open radical prostatectomy) and the control group contained 36 benign prostatic hyperplasia tissues (BPH) (transvesical open prostatectomy). The presence of HPV and the p53 codon 72 polymorphism was investigated in both groups using real-time PCR and pyrosequencing.

Results

The results of the real-time PCR showed no HPV DNA in any of the 36 BPH tissue samples. HPV-DNA was positive in only 1 of the 60 PCa samples (1.7%). The HPV type of this sample was identified as HPV-57. The distribution of the three genotypes, Arg/Arg, Arg/Pro and Pro/Pro was found to be 45.6, 45.6, and 8.8% in the PCa group and 57.1%, 34.3% and 8.6% in the control group, respectively. Compared with the control group, patients with PCa had a higher frequency of the Arg/Pro genotype and Proline allele (odds ratio (OR)=1.67, 95% confidence interval (CI)=0.68-4.09, p=0.044; OR=1.13, 95% CI=0.76-1.68, p=0.021, respectively).

Conclusions

The results of the study do not support the hyphothesis that prostate cancer is associated with HPV infection but indicated that Proline allele can be a risk factor in the development of PCa in the Turkish population.

Association between MDM2-SNP309 and p53R72P polymorphisms and the risk of bladder cancer in the Mongolian population

The current study aims to investigate whether MDM2-SNP309 and p53R72P polymorphisms were associated with the risk of bladder cancer in Mongolian populations. These polymorphisms were evaluated in 79 controls and 63 bladder cancer cases using a PCR-restriction fragment length polymorphism assay, followed by analysis using multivariate logistic regression model and the Kaplan-Meier model to determine the odds ratio (OR) and age at onset of bladder cancer, respectively. The results revealed that the homozygous (G/G) genotype of MDM2-SNP309 increased the risk of bladder cancer compared to the wild-type (T/T) genotype [OR=1.629; 95% confidence interval (CI)=0.622-4.266] among Mongolians. On the other hand, the homozygous (P/P) genotype of p53R72P tended to protect the population from bladder cancer compared with the wild-type (R/R) genotype (OR=0.445; 95% CI=0.1727-2.147). It also showed that G/G genotype of MDM2-SNP309 increased the risk of bladder cancer when combined with the R/R genotype of p53R72P (OR=3.355; 95% CI=0.3914-28.766). Stratification by smoking and history of chronic urinary tract diseases tended towards increasing the risk association of the G/G (OR=2.3704; 95% CI=0.4308-3.044) and T/G genotypes (OR=5; 95% CI=0.8442-30.4088) of MDM2-SNP309 with bladder cancer, respectively. The protective role of P/P of p53R72P remained following stratification. MDM2-SNP309 and p53R72P were not involved in early age onset of bladder cancer in Mongolian patients. Taken together, MDM2-SNP309 and p53R72P had no significant association with bladder cancer in Mongolian patients. The two SNPs were also not able to predict early age at onset of bladder cancer.

Prevention of Proliferative Vitreoretinopathy by Suppression of Phosphatidylinositol 5-Phosphate 4-Kinases

Purpose

Previous studies have shown that vitreous stimulates degradation of the tumor suppressor protein p53 and that knockdown of phosphatidylinositol 5-phosphate 4-kinases (PI5P4Kα and -β) abrogates proliferation of p53-deficient cells. The purpose of this study was to determine whether vitreous stimulated expression of PI5P4Kα and -β and whether suppression of PI5P4Kα and -β would inhibit vitreous-induced cellular responses and experimental proliferative vitreoretinopathy (PVR).

Methods

PI5P4Kα and -β encoded by PIP4K2A and 2B, respectively, in human ARPE-19 cells were knocked down by stably expressing short hairpin (sh)RNA directed at human PIP4K2A and -2B. In addition, we rescued expression of PI5P4Kα and -β by re-expressing mouse PIP4K2A and -2B in the PI5P4Kα and -β knocked-down ARPE-19 cells. Expression of PI5P4Kα and -β was determined by Western blot and immunofluorescence. The following cellular responses were monitored: cell proliferation, survival, migration, and contraction. Moreover, the cell potential of inducing PVR was examined in a rabbit model of PVR effected by intravitreal cell injection.

Results

We found that vitreous enhanced expression of PI5P4Kα and -β in RPE cells and that knocking down PI5P4Kα and -β abrogated vitreous-stimulated cell proliferation, survival, migration, and contraction. Re-expression of mouse PIP4Kα and -β in the human PI5P4Kα and -β knocked-down cells recovered the loss of vitreous-induced cell contraction. Importantly, suppression of PI5P4Kα and -β abrogated the pathogenesis of PVR induced by intravitreal cell injection in rabbits. Moreover, we revealed that expression of PI5P4Kα and -β was abundant in epiretinal membranes from PVR grade C patients.

Conclusions

The findings from this study indicate that PI5P4Kα and -β could be novel therapeutic targets for the treatment of PVR.

Association between polymorphisms in TP53 and MDM2 genes and susceptibility to prostate cancer

Tumor protein 53 (TP53), a tumor suppressor gene, is a vital cellular cancer suppressor in multicellular organisms. Murine double minute-2 (MDM2) is an oncoprotein that inhibits TP53 activity. A number of studies have examined the association of TP53 and MDM2 polymorphisms with the risk of common forms of cancer, but the findings remain inconclusive. The present study aimed to evaluate the impact of the 40-bp insertion/deletion (I/D) polymorphism (rs3730485) in the MDM2 promoter region and the 16-bp I/D polymorphism (rs17878362) in TP53 on the susceptibility of prostate cancer (PCa) in a sample of the Iranian population. This case-control study included 103 patients with pathologically confirmed PCa and 142 patients with benign prostatic hyperplasia. The MDM2 40-bp I/D and TP53 16-bp I/D polymorphism was determined using polymerase chain reaction analysis. The results demonstrated that the MDM2 40-bp I/D polymorphism increased the risk of PCa in a co-dominant inheritance model [odds ratio (OR)=1.88; 95% confidence interval (CI)=1.11-3.19; P=0.023, D/D vs. I/I], while this variant marginally increased the risk of PCa in a dominant model (OR=1.69; 95% CI=1.00-2.83; P=0.051, I/D+D/D vs. I/I). No significant association was observed between the TP53 16-bp I/D polymorphism and PCa. In conclusion, the present study demonstrated that the 40-bp I/D polymorphism in the MDM2 promoter increased the risk of PCa in an Iranian population. Further investigations with diverse ethnicities and larger sample sizes are required to verify these results.

The TP53 gene rs1042522 C>G polymorphism and neuroblastoma risk in Chinese children

TP53, a tumor suppressor gene, plays a critical role in cell cycle control, apoptosis, and DNA damage repair. Previous studies have indicated that the TP53 gene Arg72Pro (rs1042522 C>G) polymorphism is associated with susceptibility to various types of cancer. We evaluated the association of the TP53 gene rs1042522 C>G polymorphism with neuroblastoma susceptibility in a hospital-based study among the Chinese Han population. Enrolled were 256 patients and 531 controls. Odds ratios (ORs) and 95% confidence intervals (CIs) generated using logistic regression models were used to determine the strength of the association of interest. No association was detected between rs1042522 C>G polymorphism and neuroblastoma risk. In our stratification analysis of age, gender, sites of origin, and clinical stages, we observed that subjects with rs1042522 CG/GG genotypes had a lower risk of developing neuroblastoma in the mediastinum (Adjusted OR=0.52, 95% CI=0.33-0.82, P=0.005) than those carrying the CC genotype. These results indicate that TP53 gene rs1042522 C>G polymorphism may exert a weak and site-specific effect on neuroblastoma risk in Southern Chinese children and warrant further confirmation.

A functionally significant SNP in TP53 and breast cancer risk in African-American women

A coding region polymorphism exists in the TP53 gene (Pro47Ser; rs1800371) in individuals of African descent, which reduces p53 tumor suppressor function in a mouse model. It has been unclear whether this functionally significant polymorphism alters cancer risk in humans. This analysis included 6907 women with breast cancer and 7644 controls from the AMBER, ROOT, and AABC consortia. We used multivariable logistic regression to estimate associations between the TP53 Pro47Ser allele and overall breast cancer risk. Because polymorphisms in TP53 tend to be associated with cancer risk in pre-menopausal women, we also limited our analyses to this population in the AMBER and ROOT consortia, where menopausal status was known, and conducted a fixed effects meta-analysis. In an analysis of all women in the AMBER, ROOT, and AABC consortia, we found no evidence for association of the Pro47Ser variant with breast cancer risk. However, when we restricted our analysis to only pre-menopausal women from the AMBER and ROOT consortia, there was a per allele odds ratio of 1.72 (95% confidence interval 1.08-2.76; p-value = 0.023). Although the Pro47Ser variant was not associated with overall breast cancer risk, it may increase risk among pre-menopausal women of African ancestry. Following up on more studies in human populations may better elucidate the role of this variant in breast cancer etiology. However, because of the low frequency of the polymorphism in women of African ancestry, its impact at a population level may be minimal.

The Evaluation of p53 Polymorphism at Codon 72 and Association With Breast Cancer in Iran: A Systematic Review and Meta-analysis

Background

Breast cancer is the most common cancer among women in Iran and the world. Multiple environmental factors and genetic variations such as genetic polymorphisms are of its main causes. p53 gene plays an important role in conserving and sustaining the genome as a tumor suppressing gene. Change and polymorphism at codon 72 of p53 gene are correlated with increased risk of lung, mouth, endometrial, prostate, and colorectal cancers, and could be considered an indicator of susceptibility to breast cancer.

Methods

Twelve studies (1,190 cases and 1,145 control studies with evaluation of three types of Arg/Arg, Arg/Pro, and Pro/Pro genotypes) have been conducted using keywords, such as polymorphism at codon 72, gene p53 polymorphisms, and the relation between polymorphisms and breast cancer, from databases in Iran, including Magiran, Medlibe, Sid, and Iranmedex, as well as Latin databases such as PubMed, Google Scholar, Science Direct, and Scopus.

Results

The OR for Arg/Arg is 1.58 (95% CI: 2.45 to 1.01), the OR for Arg/Pro is 0.75 (95% CI: 1.10 to 0.51), and the OR for Pro/Pro is 0.62 (95% CI: 0.93 to 0.42). p53 gene polymorphism at codon 72 is statistically significant in Arg/Arg and Pro/Pro genotypes.

Conclusions

Arg/Arg genotype can be considered as a risk factor for breast cancer, and Pro/Pro genotype can be accounted for as a protective factor against breast cancer.

Molecular basis for prostate cancer racial disparities

Prostate cancer (PCa) remains the most common cancer in American men. African-American (AA) men continue to have higher PCa prevalence and mortality rates compared to men in other populations. In addition to socioeconomic factors and lifestyle differences, molecular alterations contribute to this discrepancy. We summarize molecular genetics research results interrelated with the biology of PCa racial disparity. Androgen and androgen receptor (AR) pathways have long been associated with prostate growth. Racial differences have also been found among variants of genes of the enzymes involved in androgen biosynthesis and metabolism. Growth factors and their receptors are a potential cause of the disparity in PCa. Recent molecular and biotechnological approaches in the field of proteomics and genomics will greatly aid the advancement of translational research on racial disparity in PCa, which may help, in finding new prognostic markers and novel therapeutic approaches for the treatment of PCa in AA.

Neovascularization and functional recovery after intracerebral hemorrhage is conditioned by the Tp53 Arg72Pro single-nucleotide polymorphism

Intracerebral hemorrhage (ICH) is a devastating subtype of stroke that lacks effective therapy and reliable prognosis. Neovascularization following ICH is an essential compensatory response that mediates brain repair and modulates the clinical outcome of stroke patients. However, the mechanism that dictates this process is unknown. Bone marrow-derived endothelial progenitor cells (EPCs) promote endothelial repair and contribute to ischemia-induced neovascularization. The human Tp53 gene harbors a common single-nucleotide polymorphism (SNP) at codon 72, which yields an arginine-to-proline amino-acidic substitution (Arg72Pro) that modulates the apoptotic activity of the p53 protein. Previously, we found that this SNP controls neuronal susceptibility to ischemia-induced apoptosis in vitro. Here, we evaluated the impact of the Tp53 Arg72Pro SNP on vascular repair and functional recovery after ICH. We first analyzed EPC mobilization and functional outcome based on the modified Rankin scale scores in a hospital-based cohort of 78 patients with non-traumatic ICH. Patients harboring the Pro allele of the Tp53 Arg72Pro SNP showed higher levels of circulating EPC-containing CD34⁺ cells, EPC-mobilizing cytokines - vascular endothelial growth factor and stromal cell-derived factor-1α - and good functional outcome following ICH, when compared with the homozygous Arg allele patients, which is compatible with increased neovascularization. To assess directly whether Tp53 Arg72Pro SNP regulated neovascularization after ICH, we used the humanized Tp53 Arg72Pro knock-in mice, which were subjected to the collagenase-induced ICH. The brain endothelial cells of the Pro allele-carrying mice were highly resistant to ICH-mediated apoptosis, which facilitated cytokine-mediated EPC mobilization, cerebrovascular repair and functional recovery. However, these processes were not observed in the Arg allele-carrying mice. These results reveal that the Tp53 Arg72Pro SNP determines neovascularization, brain repair and neurological recovery after ICH. This study is the first in which the Pro allele of Tp53 is linked to vascular repair and ability to functionally recover from stroke.

Esophageal Cancer in Golestan Province, Iran: A Review of Genetic Susceptibility and Environmental Risk Factors

Esophageal squamous cell carcinoma (ESCC) is an aggressive tumor that is typically diagnosed only when the tumor has gained remarkable size, extended to peripheral tissues, and led to dysphagia. Five-year survival of advanced cancer is still very poor (19%), even with improved surgical techniques and adjuvant chemoradiation therapy. Therefore, early detection and prevention are the most important strategies to reduce the burden of ESCC. Our review will focus on the studies conducted in Golestan province, an area with a high prevalence of ESCC in northern Iran. We review three aspects of the research literature on ESCC: epidemiological features, environmental factors (including substance abuse, environmental contaminants, dietary factors, and human papillomavirus [HPV]), and molecular factors (including oncogenes, tumor suppressor genes, cell cycle regulatory proteins, and other relevant biomarkers). Epidemiological and experimental data suggest that some chemicals and lifestyle factors, including polycyclic aromatic hydrocarbons (PAHs), cigarette smoking, opium use, and hot tea drinking are associated with the development of ESCC in Golestan. HPV infects the esophageal epithelium, but so far, no firm evidence of its involvement in esophageal carcinogenesis has been provided. Some of these factors, notably hot tea drinking, may render the esophageal mucosa more susceptible to injury by other carcinogens. There are few studies at molecular level on ESCC in Golestan. Increasing awareness about the known risk factors of ESCC could potentially reduce the burden of ESCC in the region. Further studies on risk factors, identifying high risk populations, and early detection are needed.

The Trp53 delta proline (Trp53ΔP) mouse exhibits increased genome instability and susceptibility to radiation-induced, but not spontaneous, tumor development

The tumor suppressor TP53 can initiate a plethora of anti-proliferative effects to maintain genomic integrity under conditions of genotoxic stress. The N-terminal proline-rich domain (PRD) of TP53 is important in the regulation of TP53 activity and stability. A common polymorphism at codon 72 in this region has been associated with altered cancer risk in humans. The Trp53ΔP mouse, which carries a germline homozygous deletion of a region of the PRD, does not develop spontaneous tumors in a mixed 129/Sv and C57BL/6 genetic background, but is highly susceptible to a broad range of tumor types following total body exposure to 4 Gy gamma (γ) radiation. This contrasts with the tumor spectrum in Trp53 null (-/-) mice, which mainly develop thymic lymphomas and osteosarcomas. Analysis of genomic instability in tissues and cells from Trp53ΔP mice demonstrated elevated basal levels of aneuploidy, but this is not sufficient to drive spontaneous tumorigenesis, which requires an additional DNA damage stimulus. Levels of genomic instability did not increase significantly in Trp53ΔP mice following irradiation exposure, suggesting that other radiation effects including tissue inflammation, altered metabolism or autophagy, may play an important role. The Trp53ΔP mouse is a novel model to dissect the mechanisms of tumor development induced by radiation exposure. © 2015 Wiley Periodicals, Inc.

Gender specific association of TP53 polymorphisms (EX4 215G>C Arg72Pro, IVS3+40-41ins16, and IVS6+62G>A), with risk of oral cancer subtypes and overall survival of the patients

Reports on the association of TP53 polymorphisms with oral cancer are not only limited but also not specific to site and/or gender. Hence, we examined the effect of TP53 polymorphisms (EX4 215G>C, IVS3+40-41ins16 and IVS6+62G>A) on buccal mucosa cancer (BMC) and tongue cancer (TC) risk, survival of patients in relation to risk and clinical factors, gender wise (excepting for estimating hazards ratio [HR]), using Fisher's Exact Test, Kaplan-Meier analysis, and Cox-proportional hazards models. The exonic polymorphism increased BMC and TC risk in males by 2-4-fold. The IVS3+40-41ins16 was protective against BMC and TC in both genders, whereas IVS6+62G>A protected only males against TC. Genotype combinations and haplotypes which altered the risk of cancers in males and females were different. TC males, aged 40-44 years and females, aged 55-59 years survived better than BMC patients. The IVS3+40-41ins16 polymorphism differentially impacted survival of female patients exposed to tobacco. TC patients with EX4 215GC with lymphovascular spread (LVS) and metastasis exhibited higher HR while, patients with EX4 215CC and perineural invasion (PNI) showed lower HR. Impact of the intronic variants along with clinical parameters on survival and HR estimates varied between BMC and TC. Our bioinformatics analysis revealed the presence of CTCF binding site within TP53 gene. In conclusion, the polymorphisms altered risk and survival of BMC and TC in a gender specific manner, which varied with mode of tobacco and/or alcohol use. The current study, therefore underscores strong need for research, stratified by tumor site and gender. © 2016 Wiley Periodicals, Inc.

Association of p53 codon72 Arg>Pro polymorphism with susceptibility to nasopharyngeal carcinoma: evidence from a case-control study and meta-analysis

Tumor suppressor p53 is a critical player in the fight against cancer as it controls the cell cycle check point, apoptotic pathways and genomic stability. It is known to be the most frequently mutated gene in a wide variety of human cancers. Single-nucleotide polymorphism of p53 at codon72 leading to substitution of proline (Pro) in place of arginine (Arg) has been identified as a risk factor for development of many cancers, including nasopharyngeal carcinoma (NPC). However, the association of this polymorphism with NPC across the published literature has shown conflicting results. We aimed to conduct a case–control study for a possible relation of p53 codon72 Arg>Pro polymorphism with NPC risk in underdeveloped states of India, combine the result with previously available records from different databases and perform a meta-analysis to draw a more definitive conclusion. A total of 70 NPC patients and 70 healthy controls were enrolled from different hospitals of north-eastern India. The p53 codon72 Arg>Pro polymorphism was typed by polymerase chain reaction, which showed an association with NPC risk. In the meta-analysis consisting of 1842 cases and 2330 controls, it was found that individuals carrying the Pro allele and the ProPro genotype were at a significantly higher risk for NPC as compared with those with the Arg allele and the ArgArg genotype, respectively. Individuals with a ProPro genotype and a combined Pro genotype (ProPro+ArgPro) also showed a significantly higher risk for NPC over a wild homozygote ArgArg genotype. Additionally, the strength of each study was tested by power analysis and genotype distribution by Hardy–Weinberg equilibrium. The outcome of the study indicated that both allele frequency and genotype distribution of p53 codon72 Arg>Pro polymorphism were significantly associated with NPC risk. Stratified analyses based on ethnicity and source of samples supported the above result.

p53: out of Africa

Somatic mutations in the tumor suppressor gene p53 occur in more than half of all human cancers. Rare germline mutations result in the Li-Fraumeni cancer family syndrome. In this issue ofGenes&Development, Jennis and colleagues (pp. 918-930) use an elegant mouse model to examine the affect of a polymorphism, P47S (rs1800371), in the N terminus of p53 that is found in Africans as well as more than a million African Americans. Remarkably, the single nucleotide change causes the mice to be substantially tumor-prone compared with littermates, suggesting that this allele causes an increased risk of developing cancer. The defect in p53 function is traced to a restriction in downstream gene regulation that reduces cell death in response to stress.

Genetic Modifiers of the p53 Pathway

The tumor suppressor gene TP53 is the most frequently mutated gene in human cancer; this gene is subject to inactivation by mutation or deletion in >50% of sporadic cancers. Genes that encode proteins that regulate p53 function, such as MDM2, MDM4, and CDKN2A (p14(ARF)) are also frequently altered in tumors, and it is generally believed that the p53 pathway is likely to be inactivated by mutation in close to 100% of human tumors. Unlike most other cancer-relevant signaling pathways, some of the genes in the p53 pathway contain functionally significant single nucleotide polymorphisms (SNPs) that alter the amplitude of signaling by this protein. These variants, thus, have the potential to impact cancer risk, progression, and the efficacy of radiation and chemotherapy. In addition, the p53 pathway plays a role in other biological processes, including metabolism and reproductive fitness, so these variants have the potential to modify other diseases as well. Here we have chosen five polymorphisms in three genes in the p53 pathway for review, two in TP53, two in MDM2, and one in MDM4. These five variants were selected based on the quality and reproducibility of functional data associated with them, as well as the convincingness of epidemiological data in support of their association with disease. We also highlight two other polymorphisms that may affect p53 signaling, but for which functional or association data are still forthcoming (KITLG and ANRIL). Finally, we touch on three questions regarding genetic modifiers of the p53 pathway: Why did these variants arise? Were they under selection pressure? And, is there compelling evidence to support genotyping these variants to better predict disease risk and prognosis?

An African-specific polymorphism in the TP53 gene impairs p53 tumor suppressor function in a mouse model

In this study, Jennis et al. characterize the first mouse model of an African-specific naturally occurring coding region variant at codon 47 of the p53 tumor suppressor gene (S47). They show that homozygous S47 mice are markedly tumor-prone and that the S47 variant impairs not only p53-mediated cell death but also the ability of p53 to transactivate a subset of genes involved in metabolism and ferroptosis.

A nonsynonymous single-nucleotide polymorphism at codon 47 in TP53 exists in African-descent populations (P47S, rs1800371; referred to here as S47). Here we report that, in human cell lines and a mouse model, the S47 variant exhibits a modest decrease in apoptosis in response to most genotoxic stresses compared with wild-type p53 but exhibits a significant defect in cell death induced by cisplatin. We show that, compared with wild-type p53, S47 has nearly indistinguishable transcriptional function but shows impaired ability to transactivate a subset of p53 target genes, including two involved in metabolism: Gls2 (glutaminase 2) and Sco2. We also show that human and mouse cells expressing the S47 variant are markedly resistant to cell death by agents that induce ferroptosis (iron-mediated nonapoptotic cell death). We show that mice expressing S47 in homozygous or heterozygous form are susceptible to spontaneous cancers of diverse histological types. Our data suggest that the S47 variant may contribute to increased cancer risk in individuals of African descent, and our findings highlight the need to assess the contribution of this variant to cancer risk in these populations. These data also confirm the potential relevance of metabolism and ferroptosis to tumor suppression by p53.

Polymorphisms in the 5' upstream regulatory region of p21(WAF1/CIP1) and susceptibility to oesophageal squamous cell carcinoma

This study aims to scan the 5'-upstream regulatory region of the p21 gene to identify all putative functional single nucleotide polymorphisms (SNPs) and to evaluate the contribution of p21 variants to oesophageal squamous cell carcinoma (ESCC) in the Chinese Han population. Common SNPs were identified, and both locus-based and haplotype-based association tests were used to evaluate the potential risk of these p21 gene polymorphisms for ESCC. Immunohistochemistry assay was further performed to detect the P21 protein expression in ESCC specimens. Twenty three SNPs were identified and seven Tagging SNPs were chosen to represent all 23 SNPs. Univariate analysis indicated that the rs3829963 C and the rs2395655 G alleles increased susceptibility to ESCC (OR = 1.606 and OR = 1.572, respectively). The rs3829963 C and rs2395655 G alleles, combined with cigarette smoking, could further increase the risk for ESCC (OR = 2.657 and OR = 2.828, respectively). Additionally, the rs2395655 G allele appeared to elevate the positive rate of P21 expression in ESCC tissues, as compared to the A allele. This report demonstrates for the first time that rs3829963 and rs2395655, in the promoter of the p21 gene are potentially functional, modulating susceptibility to ESCC among the high-risk cigarette-smoking Chinese population.

Comparison of Genetic Variants in Cancer-Related Genes between Chinese Hui and Han Populations

Background

The Chinese Hui population, as the second largest minority ethnic group in China, may have a different genetic background from Han people because of its unique demographic history. In this study, we aimed to identify genetic differences between Han and Hui Chinese from the Ningxia region of China by comparing eighteen single nucleotide polymorphisms in cancer-related genes.

Methods

DNA samples were collected from 99 Hui and 145 Han people from the Ningxia Hui Autonomous Region in China, and SNPs were detected using an improved multiplex ligase detection reaction method. Genotyping data from six 1000 Genomes Project population samples (99 Utah residents with northern and western European ancestry (CEU), 107 Toscani in Italy (TSI), 108 Yoruba in Ibadan (YRI), 61 of African ancestry in the southwestern US (ASW), 103 Han Chinese in Beijing (CHB), and 104 Japanese in Tokyo (JPT)) were also included in this study. Differences in the distribution of alleles among the populations were assessed using χ² tests, and F_ST was used to measure the degree of population differentiation.

Results

We found that the genetic diversity of many SNPs in cancer-related genes in the Hui Chinese in Ningxia was different from that in the Han Chinese in Ningxia. For example, the allele frequencies of four SNPs (rs13361707, rs2274223, rs465498, and rs753955) showed different genetic distributions (p<0.05) between Chinese Ningxia Han and Chinese Ningxia Hui. Five SNPs (rs730506, rs13361707, rs2274223, rs465498 and rs753955) had different F_ST values (F_ST>0.000) between the Hui and Han populations.

Conclusions

These results suggest that some SNPs associated with cancer-related genes vary among different Chinese ethnic groups. We suggest that population differences should be carefully considered in evaluating cancer risk and prognosis as well as the efficacy of cancer therapy.

Association of XRCC1 Arg399GIn and Tp53 Arg72Pro polymorphisms and increased risk of uterine leiomyoma - A case-control study

The aim of present study was to investigate the role of the X-ray repair cross-complementing protein1 (XRCC1) and Tumor protein p53 (Tp53) polymorphisms in Uterine Leiomyoma (UL) susceptibility in southeastern Iran. This case control study was performed on 139 women with UL and 149 age, BMI and ethnicity matched healthy women. All women were genotyped for the XRCC1 Arg399Gln, XRCC1 Arg194Trp and Tp53 Arg72Pro polymorphisms. The frequency of Tp53 72 Pro/Pro genotype was significantly higher in UL women compared to controls. The risk of UL was 1.5 fold higher in women with the Pro/Pro genotype (OR, 1.5 [95% CI, 1.1 to 2.1], p = 0.012). Moreover, the frequency of the Pro allele was significantly higher in the UL women. Although the frequency of XRCC1 Arg399Gln genotypes did not significantly differ between UL and control groups before adjusting for age, there was an association between the XRCC1 Arg/Gln genotype and UL after adjusting for age (OR, 1.8 [95% CI, 1.1 to 3]). No association was observed between the XRCC1 Arg194Trp polymorphism and UL. The Pro/Pro genotype of Tp53 Arg72Pro polymorphism was associated with UL susceptibility. In addition, the XRCC1 Arg/Gln genotype was associated with increased risk of UL after adjusting for age.

Association of a p53 codon 72 gene polymorphism with environmental factors and risk of lung cancer: a case control study in Mizoram and Manipur, a high incidence region in North East India

BACKGROUND

A very high incidence of lung cancer is observed in Mizoram and Manipur, North East India. We conducted a population based case control study to establish associations of p53 codon 72 polymorphisms and interactions with environmental factors for this high incidence.

MATERIAL AND METHODS

A total of 272 lung cancer cases and 544 controls matched for age (±5 years), sex and ethnicity were collected and p53 codon 72 polymorphism genotypes were analyzed using a polymerase chain based restriction fragment length polymorphism assay. We used conditional multiple logistic regression analysis to calculate adjusted odds ratios and 95% confidence intervals after adjusting for confounding factors.

RESULTS

p53 Pro/Pro genotype was significantly associated with increased risk of lung cancer in the study population (adjusted OR=2.14, CI=1.35-3.38, p=0.001). Interactions of the p53 Pro/Pro genotype with exposure to wood smoke (adjusted OR=3.60, CI=1.85-6.98, p<0.001) and cooking oil fumes (adjusted OR=3.27, CI=1.55-6.87, p=0.002), betel quid chewing (adjusted OR=3.85, CI=1.96- 7.55, p<0.001), tobacco smoking (adjusted OR=4.42, CI=2.27-8.63, p<0.001) and alcohol consumption (adjusted OR=3.31, CI=1.10-10.03, p=0.034) were significant regarding the increased risk of lung cancer in the study population.

CONCLUSIONS

The present study provided preliminary evidence that a p53 codon 72 polymorphism may effect lung cancer risk in the study population, interacting synergistically with environmental factors.