Polymorphic variants in the p53 pathway

Three-dimensional nuclear architecture distinguishes thyroid cancer histotypes

Molecular markers can serve as diagnostic tools to support pathological analysis in thyroid neoplasms. However, because the same markers can be observed in some benign thyroid lesions, additional approaches are necessary to differentiate thyroid tumor subtypes, prevent overtreatment and tailor specific clinical management. This applies particularly to the recently described variant of thyroid cancer referred to as noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP). This variant has an estimated prevalence of 4.4% to 9.1% of all papillary thyroid carcinomas worldwide. We studied 60 thyroid lesions: 20 classical papillary thyroid carcinoma (CPTC), 20 follicular variant of PTC (FVPTC) and 20 NIFTP. We examined morphological and molecular features to identify parameters that can differentiate NIFTP from the other PTC subtypes. When blindly investigating the nuclear architecture of thyroid neoplasms, we observed that NIFTP has significantly longer telomeres than CPTC and FVPTC. Super-resolved 3D-structured illumination microscopy demonstrated that NIFTP is heterogeneous and that its nuclei contain more densely packed DNA and smaller interchromatin spaces than CPTC and FVPTC, a pattern that resembles normal thyroid tissue. These data are consistent with the observed indolent biological behavior and favorable prognosis associated with NIFTP, which lacks BRAFV600E mutations. Of note, next-generation thyroid oncopanel sequencing was unable to distinguish the thyroid cancer histotypes in our study cohort. In summary, our data suggest that 3D nuclear architecture can be a powerful analytical tool to diagnose and guide clinical management of NIFTP.

SARS-CoV-2: Understanding the Transcriptional Regulation of ACE2 and TMPRSS2 and the Role of Single Nucleotide Polymorphism (SNP) at Codon 72 of p53 in the Innate Immune Response against Virus Infection

Human ACE2 and the serine protease TMPRSS2 of novel SARS-CoV-2 are primary entry receptors in host cells. Expression of these genes at the transcriptional level has not been much discussed in detail. The ISRE elements of the ACE2 promoter are a binding site for the ISGF3 complex of the JAK/STAT signaling pathway. TMPRSS2, including IFNβ, STAT1, and STAT2, has the PARP1 binding site near to TSS either up or downstream promoter region. It is well documented that PARP1 regulates gene expression at the transcription level. Therefore, to curb virus infection, both promoting type I IFN signaling to boost innate immunity and prevention of virus entry by inhibiting PARP1, ACE2 or TMPRSS2 are safe options. Most importantly, our aim is to attract the attention of the global scientific community towards the codon 72 Single Nucleotide Polymorphism (SNP) of p53 and its underneath role in the innate immune response against SARS-CoV-2. Here, we discuss codon 72 SNP of human p53's role in the different innate immune response to restrict virus-mediated mortality rate only in specific parts of the world. In addition, we discuss potential targets and emerging therapies using bioengineered bacteriophage, anti-sense, or CRISPR strategies.

Functional interplay among thiol-based redox signaling, metabolism, and ferroptosis unveiled by a genetic variant of TP53

The p53 tumor suppressor protein is a transcription factor and master stress response mediator, and it is subject to reduction-oxidation (redox)-dependent regulation. The P47S variant of TP53, which exists primarily in African-descent populations, associates with an elevated abundance of low molecular weight (LMW) thiols, including glutathione (GSH) and coenzyme A (CoA). Here we show that S47 and P47 cells exhibit distinct metabolic profiles, controlled by their different redox states and expression of Activating Transcription Factor-4 (ATF4). We find that S47 cells exhibit decreased catabolic glycolysis but increased use of the pentose phosphate pathway (PPP), and an enhanced abundance of the antioxidant, NADPH. We identify ATF4 as differentially expressed in P47 and S47 cells and show that ATF4 can reverse the redox status and rescue metabolism of S47 cells, as well as increase sensitivity to ferroptosis. This adaptive metabolic switch is rapid, reversible, and accompanied by thiol-mediated changes in the structures and activities of key glycolytic signaling pathway proteins, including GAPDH and G6PD. The results presented here unveil the important functional interplay among pathways regulating thiol-redox status, metabolic adaptation, and cellular responses to oxidative stress.

Genetic Susceptibility for Cervical Cancer in African Populations: What Are the Host Genetic Drivers?

Human papillomavirus (HPV) is an essential but not a sufficient cervical cancer etiological factor. Cancer promoters, such as host genetic mutations, significantly modulate therapeutic responses and susceptibility. In cervical cancer, of interest have been viral clearing genes and HPV oncoprotein targets, for which conflicting data have been reported among different populations. This expert analysis evaluates cervical cancer genetic susceptibility biomarkers studied in African populations. Notably, the past decade has seen Africa as a hotbed of biomarker and precision medicine innovations, thus potentially informing worldwide biomarker development strategies. We conducted a critical literature search in PubMed/MEDLINE, Google Scholar, and Scopus databases for case-control studies reporting on cervical cancer genetic polymorphisms among Africans. We found that seven African countries conducted cervical cancer molecular epidemiology studies in one of Casp8, p53, CCR2, FASL, HLA, IL10, TGF-beta, and TNF-alpha genes. This analysis reveals a remarkable gap in cervical cancer molecular epidemiology among Africans, whereas cervical cancer continues to disproportionately have an impact on African populations. Genome-wide association, whole exome- and whole-genome sequencing studies confirmed the contribution of candidate genes in cervical cancer. With such advances and omics technologies, the role of genetic susceptibility biomarkers can be exploited to develop novel interventions to improve current screening, diagnostic and prognostic methods worldwide. Exploring these genetic variations is crucial because African populations are genetically diverse and some variants or their combined effects are yet to be discovered and translated into tangible clinical applications. Thus, translational medicine and flourishing system sciences in Africa warrant further emphasis in the coming decade.

TP53 codon 72 Polymorphism and bladder cancer risk: a meta-analysis and emphasis on the role of tumor or smoking status

Background: Various studies had explored the relationship between TP53 codon 72 polymorphisms and the risk of bladder cancer (BC). However, their results remained inconsistent and the definite role of smoking or tumor status associated with this polymorphism in BC cases was seldom involved. Hence, this meta-analysis was to disclose such associations. Methods: Systematical and comprehensive retrieval of online databases PubMed, PMC, EMBASE and Web of Science were conducted to obtain eligible studies, up to May 30th, 2018. Pooled odds ratios (ORs) with 95% confidence intervals (CI) were utilized to assess the associations between TP53 codon 72 polymorphisms and BC susceptibilities under five genetic comparison models. Results: Ultimately, this meta-analysis enrolled 22 applicable studies with 3,791 BC cases and 4,917 controls. Our results suggested that the variant genotypes were associated with BC risk in Asian subgroup (allele model: OR=1.19, 95% CI=1.04-1.34; dominant model: OR=1.27, 95% CI=1.06-1.52; homozygote model: OR=1.36, 95% CI=1.03-1.80), while negative outcomes were presented in Caucasians. In the relationship between TP53 codon 72 polymorphisms and BC tumor stage in Asian group, positive results were presented in allele model: OR=1.68, 95% CI=1.04-2.72; dominant model: OR=2.46, 95% CI=1.08-5.61; heterozygous model: OR=2.32, 95% CI=1.04-5.14; homozygote model: OR=2.66, 95% CI=1.04-6.81. However, no evidence was revealed between this polymorphism and BC tumor grade. Besides, significant associations were displayed between TP53 codon 72 polymorphism and smoking status (allele model: OR=1.40, 95% CI=1.06-1.84; dominant model OR=1.72, 95% CI=1.18-2.50; heterozygous model: OR=1.77, 95% CI=1.19-2.64). Conclusion: Taken together, our results shed light on that TP53 codon 72 polymorphism was significantly associated with the susceptibility to BC in Asians. In addition, positive associations were also revealed between this polymorphism and tumor stage/smoking status in BC cases.

Control of metabolism by p53 - Cancer and beyond

p53 is an important tumour suppressor gene, with loss of p53 contributing to the development of most human cancers. However, the activation of p53 in response to stress signals underpins a role for p53 in diverse aspects of health and disease. Activities of p53 that regulate metabolism can play a role in maintaining homeostasis and protecting cells from damage - so preventing disease development. By contrast, either loss or over-activation of p53 can contribute to numerous metabolic pathologies, including aging, obesity and diabetes.

Blood-tissue analysis of TP53 polymorphisms and survival of patients with glioma

BACKGROUND

The role of single nucleotide polymorphisms (SNPs) in TP53 in the pathogenesis of glioma is still debated. The aim of our study was to investigate the role of several TP53 SNPs in the risk of glioma and their possible role as prognostic biomarkers of overall and progression-free survival.

METHODS

We examined 12 SNPs in TP53 from peripheral blood and neoplastic tissue of patients with a diagnosis of glioma who underwent surgery from 2012 to 2015. Direct genomic sequencing of TP53 was performed to detect the presence of polymorphisms. We compared data with a matched cancer-free control group and the NCBI SNPs database. Overall and progression-free survival were analyzed in patients with glioblastoma subjected to gross total resection and concomitant radio-chemotherapy.

RESULTS

No association was observed with glioma susceptibility and overall survival. Two new SNPs were detected: c.97-46 G>A (intron 3) and c.783-31 A>G (intron 7). The number of SNPs observed was higher (21.4%) in blood than in tumoral samples. We observed a significant reduction in progression-free survival in patients with at least one exonic SNP.

CONCLUSIONS

We can hypothesize an involvement of TP53 SNPs in response mechanisms to adjuvant treatment that may affect progression-free survival. Moreover, our blood-tissue combined study revealed a significant difference in SNPs between blood and tumoral samples, probably due to glioma heterogeneity and genomic instability.

Association of p53 Codon 72 Polymorphism with Breast Cancer in a Rwandese Population

BACKGROUND AND AIMS

A common polymorphism in the tumor suppressor gene p53 at codon 72 has been suggested to play a role in the development of a number of cancers. This polymorphism has been studied in many populations worldwide, with conflicting results. The present study was planned to assess the association of p53 codon 72 polymorphism with breast cancer development in a Rwandese population.

METHODS

In this study, the polymorphism was examined by allele-specific PCR analysis in 40 patients with breast cancer and 39 healthy controls.

RESULTS

The heterozygous genotype Pro/Arg prevailed in both breast cancer patients and controls, and was present in 80% (32/40) and 92.3% (36/39) of cases, respectively. No statistically significant association was observed between p53 codon 72 polymorphism and breast cancer risk. Distribution of p53 genotypes was also studied according to familial history, tumor grade, and clinical stage, and results clearly showed no statistically significant difference.

CONCLUSION

These results suggest that p53 codon 72 polymorphism could not be assessed as a risk factor marker for predisposition to breast cancer in Rwanda. However, further studies using larger sample sizes are needed to provide more conclusive results and to investigate other genetic mutations affecting the activity of p53.

The codon 72 polymorphism of p53 influences cell fate following nutrient deprivation

The TP53 gene is distinguished as the most frequently mutated gene in cancer. Unlike most cancer-relevant genes, the TP53 gene is also distinguished by the existence of coding region polymorphisms that alter p53 sequence, and in some cases, also alter p53 function. A common coding region variant at amino acid 72 of p53 encodes either proline (P72) or arginine (R72). P72 is the ancestral variant and is most common in populations near the equator. The frequency of the R72 variant increases in a linear manner with latitude. To date, why the R72 variant arose in humans and was possibly selected for has remained unclear. Here-in we show that this single nucleotide polymorphism (SNP) influences the phosphorylation of p53 and the transactivation of the key p53 target CDKN1A (p21) specifically in response to nutrient deprivation, but not in response to conventional cytotoxic agents. Following activation of the kinase AMPK, R72 cells show increased phosphorylation on serine-15 and increased transactivation of the cyclin-dependent kinase inhibitor CDKN1A (p21) and the metabolic response genes PPARGC1B (PGC-1β) and PRKAB2 (AMPK-β2). This is accompanied by increased growth arrest and decreased apoptosis in R72 cells compared with P72 cells. The combined data fit best with the hypothesis that the R72 polymorphism confers increased cell survival in response to nutrient deprivation. This differential response to nutrient deprivation may explain part of selection for this SNP at northern latitudes, where nutrient deprivation might have been more frequent.

Hsa-miR-137, hsa-miR-520e and hsa-miR-590-3p perform crucial roles in Lynch syndrome

The aim of the present study was to identify the differentially expressed microRNAs (DEMs) between Lynch syndrome (LS) and the normal colonic (N-C) control samples, predict the target genes (TGs) and analyze the potential functions of the DEMs and TGs. The miRNA expression dataset GSE30454, which included data of 13 LS and 20 N-C tissue samples, was downloaded from the Gene Expression Omnibus. The classical t-test in Linear Models for Microarray Data package was used for DEM identification. TG prediction was performed using 5 databases. The regulatory network of the DEMs and their TGs was constructed using Cytoscape. Functional and pathway enrichment analysis was performed. The transcription factors (TFs), tumor-associated genes (TAG) and tumor suppressor genes (TSGs) were then identified. Three key DEMs hsa-miR-137, hsa-miR-520e, and hsa-miR-590-3p were identified. Hsa-miR-520e and hsa-miR-137 had 4 common TGs, including SNF related kinase, metal-regulatory transcription factor 1 (MTF1), round spermatid basic protein 1 and YTH N6-methyladenosine RNA binding protein 3; hsa-miR-590-3p and hsa-miR-137 had 14 common TGs, including NCK adaptor protein 1 (NCK1), EPH receptor A7, and stress-associated endoplasmic reticulum protein 1; hsa-miR-590-3p and hsa-miR-520e had 12 common TGs, including Krüppel-like factor (KLF) 13, twinfilin actin binding protein 1, and nuclear factor I B. Through the functional and pathway enrichments analysis, MTF1 was involved in regulation of gene expression and metabolic processes, and sequence-specific DNA binding TF activity. KLF13 was involved in regulation of gene expression and regulation of cellular metabolic processes. NCK1 was enriched in the axon guidance pathway. In addition, the functional and pathway enrichment analysis showed certain TGs, such as hypoxia-inducible factor 1α, AKT serine/threonine kinase 2, and rapamycin-insensitive companion of mammalian target of rapamycin, participated in the mTOR signaling pathway. The 3 key DEMs hsa-miR-137, hsa-miR-520e, and hsa-miR-590-3p may have important roles in the process of LS.

A link between TP53 polymorphisms and metabolism

Besides being a critical tumor suppressor, the TP53 gene also plays a role in metabolism and recent studies in humans have implicated the codon 72 polymorphism of TP53 in this role. Using a humanized knock-in mouse model for these TP53 variants, we show that this polymorphism has a significant impact on the metabolic response to a high-fat diet.

Association of the rs1042522 polymorphism with increased risk of prostate adenocarcinoma in the Pakistani population and its HuGE review

Prostate adenocarcinoma is one of the leading causes of cancer related mortality in men but still limited knowledge is available about its associated functional SNPs including rs1042522 (Pro72Arg). The present study was undertaken to explore the association of this SNP with susceptibility to prostate adenocarcinoma along with its structural and functional impacts in the Pakistani population in a case-control study. Three-dimensional structure of human TP53 with Pro72Arg polymorphism was predicted through homology modeling, refined and validated for detailed structure-based assessment. We also carried out a HuGE review of the previous available data for this polymorphism. Different genetic models were used to evaluate the genotypes association with the increased risk of PCa (Allelic contrast: OR=0.0.34, 95%CI 0.24-0.50, p=0.000; GG vs CC: OR=0.17, 95%CI 0.08-0.38, p=0.000; Homozygous: OR=0.08, 95%CI 0.04-0.15, p=0.000; GC vs CC: OR=2.14, 95%CI 1.01-4.51, p=0.046; Recessive model: OR=0.10, 95%CI 0.05-0.18, p=0.000; Log Additive: OR=3.54, 95%CI 2.13-5.89, p=0.000) except the Dominant model (OR=0.77, 95%CI 0.39-1.52, p=0.46). Structure and functional analysis revealed that the SNP in the proline rich domain is responsible for interaction with HRMT1L2 and WWOX. In conclusion, it was observed that the Arg coding G allele is highly associated with increased risk of prostate adenocarcinoma in the Pakistani population (p=0.000).

No Evidence of Association of the Arg72Pro p53 Gene Polymorphism with Cancer Risk in the Saudi Population: a Meta-Analysis

BACKGROUND

Earlier studies on the association between p53 codon 72 Arg>Pro polymorphism and cancer risk were inconclusive and conflicting for the Saudi population. Therefore, we performed a meta-analysis to investigate the relationship between the codon 72 Arg>Pro polymorphism and overall cancer risk in Saudi Arabia.

MATERIALS AND METHODS

We searched all eligible published studies and data were pooled together to perform the meta-analysis. Pooled odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated for homozygous, heterozygous, dominant and recessive genetic models.

RESULTS

A total of five eligible published studies covering 502 cancer cases and 784 healthy controls were included in the meta-analysis. No publication bias was detected in this study. The results suggested that the variant (Pro vs Arg: p=0.960; OR=1.004, 95% CI=0.852-1.183), homozygous (Pro.Pro vs Arg.Arg: p=0.970; OR=1.006, 95% CI=0.729-1.390), heterozygous (Arg.Pro vs Arg.Arg: p=0.473; OR=0.783, 95% CI=0.402-1.527) carriers were not associated with overall cancer risk. Similarly, dominant (Pro.Pro+Pro.Arg vs Arg.Arg: p=0.632; OR=0.886, 95% CI=0.540-1.454) and recessive (Pro.Pro vs Pro.Arg+Arg.Arg: p=0.269; OR=1.163, 95%CI=0.890-1.521) models also did not indicate increased risk of cancer.

CONCLUSIONS

The current meta-analysis suggests that the codon 72 Arg>Pro polymorphism of the p53 gene might not contribute to cancer susceptibility in Saudi population. Future well designed large case control studies are needed to validate our findings.

TP53 polymorphisms in sporadic North Indian breast cancer patients

BACKGROUND

The purpose of this study was to evaluate the potential association of five (p.P47S, p.R72P, PIN3 Ins16bp, p.R213R and r.13494g>a) polymorphisms of TP53 with the risk of developing breast cancer in North Indian Punjabi population.

METHODS

We screened DNA samples of 200 sporadic breast cancer patients (197 females and 3 males) and 200 unrelated healthy, gender and age matched individuals for the polymorphisms.

RESULTS

For the p.P47S polymorphism, we observed the PP genotype in 99.5% of the patients and PS genotype in only 1 patient. All the controls had the wild type PP genotype. The frequency of RR, RP and PP genotype of p.R72P was 23.5% vs 33.5%, 51.5% vs 45.5% and 25% vs 21% in patients and controls respectively. Heterozygous (RP) genotype was increased in breast cancer patients as compared to controls (51.5 vs 45.5%) and showed 1.61 fold significantly increased risk for breast cancer (OR=1.61, 95% CI, 1.01-2.58, p=0.04). In breast cancer patients the frequencies of A1A1, A1A2 and A2A2 genotypes of PIN3 Ins16bp polymorphism were 67%, 26% and 7% respectively whereas in controls the genotype frequencies were 68.5%, 27.5% and 4% respectively, with no significant difference. For p.R213R (c.639A>G), all individuals had homozygous wild type genotype. The frequencies of GG, GA and AA genotypes of TP53 r.13494g>a polymorphism were 62 vs 67.5%, 33 vs 28% and 5 vs 4.5% in patients and controls respectively, again without significant difference. We observed that RP- A1A1 genotype combination of p.R72P and PIN3 Ins16bp and RP-GG combination of p.R72P and r.13494g>a polymorphism showed significant risk of breast cancer (OR=1.65, 95%CI: 0.98-2.78, p=0.05; OR=1.72, 95%CI: 1.01-2.92, p=0.04).

CONCLUSION

The results of present study indicated that among the five TP53 polymorphisms investigated, the p.R72P polymorphism, and the RP-A1A1 and RP-GG genotype combination contribute to breast cancer susceptibility in North Indians.

Molecular mechanisms of hepatic apoptosis regulated by nuclear factors

Apoptosis is a prominent characteristic in the pathogenesis of liver disease. The mechanism of hepatic apoptosis is not well understood. Hepatic apoptosis alters relative levels of nuclear factors such as Foxa2, NF-κB, C/EBPβ, and p53. Regulation of nuclear factors modulates the degree of hepatic apoptosis and the progression of liver disease. Nuclear factors have distinctive mechanisms to mediate hepatic apoptosis. The modification of nuclear factors is a novel therapeutic strategy for liver disease as demonstrated by pre-clinical models and clinical trials.

Analysis of TP53 polymorphisms in North Indian sporadic esophageal cancer patients

BACKGROUND

To investigate the relationship of five TP53 polymorphisms (p.P47S, p.R72P, PIN3 ins16bp, p.R213R and r.13494g>a) with the esophageal cancer (EC) risk in North Indians.

MATERIALS AND METHODS

Genotyping of p.P47S, p.R72P, PIN3 ins16bp, p.R213R and r.13494g>a polymorphisms of TP53 in 136 sporadic EC patients and 136 controls using polymerase chain reaction and PCR-RFLP.

RESULTS

The frequencies of genotype RR, RP and PP of p.R72P polymorphism were 16.91 vs 26.47%, 58.82 vs 49.27% and 24.27 vs 24.27% among patients and controls respectively. We observed significantly increased frequency of RP genotype in cases as compared to controls (OR=1.87, 95% CI, 1.01-3.46, p=0.05). The frequencies of genotype A1A1, A1A2 and A2A2 of PIN3 ins16bp polymorphism were 69.12 vs 70.59%, 27.20 vs 25% and 3.68 vs 4.41% among patients and controls. There was no significant difference among genotype and allele distribution between patients and controls. The frequencies of genotype GG, GA and AA of r.13494g>a polymorphism were 62.50 vs 64.70%, 34.56 vs 30.15% and 2.94 vs 5.15% among patients and controls respectively. No significant difference between genotype and allele frequency was observed in the patients and controls. For p.P47S and p.R213R polymorphisms, all the cases and controls had homozygous wild type genotype. The RP-A1A1-GG genotype combination shows significant risk for EC (OR=2.01, 95%CI: 1.01-3.99, p=0.05).

CONCLUSIONS

Among the five TP53 polymorphisms investigated, only p.R72P polymorphism may contributes to EC susceptibility.

Identification of TRIML2, a novel p53 target, that enhances p53 SUMOylation and regulates the transactivation of proapoptotic genes

The tumor-suppressor protein p53, encoded by TP53, inhibits tumorigenesis by inducing cell-cycle arrest, senescence, and apoptosis. Several genetic polymorphisms exist in TP53, including a proline to arginine variant at amino acid 72 (P72 and R72, respectively); this polymorphism alters p53 function. In general, the P72 variant shows increased ability to induce cell-cycle arrest, whereas the R72 variant possesses increased ability to induce apoptosis, relative to P72. At present, the underlying mechanisms for these functional differences are not fully understood. Toward elucidating the molecular basis for these differences, a gene-expression microarray analysis was conducted on normal human fibroblast cells that are homozygous for P72 and R72 variants, along with subclones of these lines that express a p53 short hairpin (shp53). Approximately three dozen genes were identified whose transactivation is affected by the codon 72 polymorphism. One of these is the tripartite-motif family-like 2 (TRIML2) gene, which is preferentially induced by the R72 variant. Importantly, the accumulated data indicate that TRIML2 interacts with p53, and facilitates the modification of p53 with SUMO2. TRIML2 also enhances the ability of p53 to transactivate a subset of proapoptotic target genes associated with prolonged oxidative stress, including PIDD, PIG3 (TP53I3), and PIG6 (PRODH). These data indicate that TRIML2 is part of a feed-forward loop that activates p53 in cells expressing the R72 variant, particularly after prolonged stress.

IMPLICATIONS

The defined actions of TRIML2, in part, explain the underlying molecular basis for increased apoptotic potential of the R72 variant of p53.

Association of EGF and p53 gene polymorphisms and colorectal cancer risk in the Slovak population

During the transformation process single nucleotide polymorphisms (SNPs) of key genes, such as p53 Arg72Pro or EGF A61G, may mediate various cellular processes. These variants may be associated with colorectal cancer risk (CRC), but conflicting findings have been reported. The purpose of this study was to determine the association of the SNPs in 5′ UTR of EGF A61G and p53 Arg72Pro and CRC in the Slovak population. The present case-control study was carried out in 173 confirmed CRC patients and 303 healthy subjects. Genotyping was performed by PCR-RFLP methods. Significant association was observed between age and CRC risk (p=0.001). Lower CRC risk was seen in younger patients carrying genotype p53 Arg72Pro (0.14; 95% CI 0.02–0.99, p=0.049). Gender-stratified analysis showed a significant inverse association of the polymorphism EGF G61G with CRC risk (0.48; 95% CI 0.2–0.9, p=0.04) only in male patients. Tumour site genotype distribution revealed that female patients with localized colon cancer were significantly associated with p53 Pro72Pro genotype (4.0; 95% CI 1.27–12.7, p=0.04) whereas the cancer of rectosigmoid junction was associated with the EGF G61G genotype (4.5; 95% CI 1.2–16.97, p=0.02). Combination of p53 Arg72Pro or EGF A61G polymorphisms were not associated with CRC risk by using logistic regression.

P53 (Pro72Arg) polymorphism associated with the risk of oral squamous cell carcinoma in gutka, niswar and manpuri addicted patients of Pakistan

OBJECTIVES

The chewing habit of paan, chhaliya, and tobacco is common in the traditional culture of Pakistan. Currently, niswar, gutka and manpuri are also commercially available in the Pakistani market. Epidemiologic evidences and increased rate of oral squamous cell carcinoma (OSCC) cases may indicate a direct relationship of these chewing habits with oral carcinogenesis. The p53 gene has been known to be a tumor suppressor gene that is found mutated in common human cancers. The p53 gene contains a single nucleotide polymorphism at codon 72 of exon 4 which encodes either proline (Pro) or arginine (Arg). The aim of the present study was to investigate association of p53 gene codon 72 polymorphism with patients of oral squamous cell carcinoma consuming these carcinogenic chewable materials.

MATERIALS AND METHODS

Blood and tissue samples of 260 OSCC patients were collected with informed consent from the local hospitals of Karachi. The patients were compared with controls of similar age and sex. The exon 4 of p53 gene was examined by PCR-SSCP. The tumor samples showing mobility shift were purified and sequenced.

RESULTS

The C>G missense mutation at nucleotide position 215 of the coding sequence was identified which substitutes proline with arginine at codon 72 of p53 protein. When the data for CCC72CGC polymorphism was analyzed statistically, a significant difference was observed between OSCC and control samples. The Pro allelic frequencies were significantly higher in OSCC patients as compare to controls. The current study indicated the Pro form of p53 codon 72 increases the risk of developing OSCC in Pakistani population. The risk ratio for Pro allele was 1.5004 (95% confidence interval: 1.2559 to 1.7924) and odds ratio of Pro allele was 2.389 (95% confidence interval: 1.5591 to 2.8137) in comparison with the Arg and Pro alleles in the OSCC group.

CONCLUSION

These evidences suggest that there may be specific genetic targets with these chewing ingredients that are responsible for causing OSCC. The p53 codon 72 polymorphism is associated with OSCC at somatic cell level but the polymorphism was not associated at inherited level.

Colorectal cancer: molecular mutations and polymorphisms

Colorectal cancer (CRC) is one of the major causes of mortality and morbidity, and is the third most common cancer in men and the second most common cancer in women worldwide. The incidence of CRC shows considerable variation among racially or ethnically defined populations in multiracial/ethnic countries. The tumorigenesis of CRC is either because of the chromosomal instability (CIN) or microsatellite instability (MIN) or involving various proto-oncogenes, tumor-suppressor genes, and also epigenetic changes in the DNA. In this review I have focused on the mutations and polymorphisms of various important genes of the CIN and MIN pathways which have been implicated in the development of CRC.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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

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

The p53 Codon 72 Polymorphism Modifies the Cellular Response to Inflammatory Challenge in the Liver

The p53 protein is a critical stress-response mediator and signal coordinator in cellular metabolism and environmental exposure to deleterious agents. In human populations, the p53 gene contains a common single nucleotide polymorphism (SNP) affecting codon 72 that determines whether a proline (P72) or an arginine (R72) is present at this amino acid position of the polypeptide. Previous studies carried out using human populations, mouse models, and cell culture analyses have provided evidence that this amino acid difference can alter p53 functional activities, and potentially also can affect clinical presentation of disease. The clinical presentation associated with many forms of liver disease is variable, but few of the responsible underlying genetic factors or molecular pathways have been identified. The aim of the present study was to investigate whether the p53 codon 72 polymorphism influences the cellular response to hepatic stresses. A humanized p53 knock-in (Hupki) mouse model was used to address this issue. Mice expressing either the P72 or R72 normal variation of p53 were given an acute-, intermittent- or a chronic challenge, associated with exposure to lipopolysaccharide, D-galactosamine, or a high-fat diet. The results reveal that the livers of the P72 and R72 mice exhibit notable differences in inflammatory and apoptotic response to these distinct forms of stress. Interestingly the influence of this polymorphism on the response to stress is context dependent, with P72 showing increased response to liver toxins (lipopolysaccharide and D-galactosamine), but R72 showing increased response to metabolic stress (high fat diet). When taken together, these data point to the p53 codon 72 polymorphism as an important molecular mediator of events contributing to hepatic inflammation and metabolic homeostasis.

[The new function of p53 family and its pathway related proteins in female reproduction]

p53 is an important tumor suppressor gene and one of the key genes in sensing and regulating responses to the environmental stress. Recent study showed that cold winter temperature naturally selected p53 Arg72 in eastern Asian population, suggesting that p53 plays a role in reproduction. It has also been reported that some SNPs of p53, Mdm2(Murine double minute 2), MdmX and Hausp (Herpes virus-associated ubiquitin-specific protease) in p53 pathway are associated with the risk of the women's reproduction disorder. p53 regulates the LIF (leukaemia inhibitory factor) expression level by its DBD domain, and thus contributes to female reproduction by affecting the embryo implantation process. The MDM2, MDMX, and HAUSP proteins regulates the level and activity of p53 protein, which are critical for the appropriate p53 response in the embryo implantation process. The members of p53 family, p63 and p73, also play roles in female reproduction through other pathways. p63 has been implicated as a major regulator of oocyte death following treatment with irradiation and chemotherapeutic drugs, which prevents fetal malformation. p73 regulates the formation of spindle assembly complex(SAC). The dysfunction of SAC results in poor blastocyst quality and defects in kinetochore-microtubule associations, which leads to aneuploidy. This review summarized the function of p53 family and its pathway related proteins in female reproduction, pointed out a new method in improving the success rate in IVF-ET, and provided a new diagnosis idea for unexplained infertile women. It will facilitate personalized strategies in the infertility therapy.

p53 and risk of endometriosis in Indian women

AIM

To investigate the role of loss of heterozygosity (LOH), single nucleotide polymorphisms (SNPs), and the expression of gene p53 in the pathogenesis of endometriosis.

METHODS

LOH at the p53 gene locus (17p13.1) was examined in matched ectopic and eutopic endometrial tissues from 31 endometriosis patients by polymerase chain reaction (PCR)-GeneScan analysis. The genotyping of selected p53 SNPs (n=10) was carried out on genomic DNA of blood from endometriosis patients (n=720) and controls (n=500) by PCR sequencing. The p53 expression levels were analyzed in the endometrial tissues from endometriosis patients (n=5) and controls (n=4) by Western blot and immunohistochemical analysis.

RESULTS

LOH was observed at the 17p13.1 locus (38.7%) in the ectopic endometrium but not in the eutopic endometrium of patients. The genotype (p=0.909) and allele (p=0.729) distribution of the p53 codon Arg72Pro polymorphism was not significantly different between patients and controls. The polymorphism was not observed at codon 47 along the other SNPs studied. There was no preferential loss of either "Arg72" or "Pro72" alleles among the LOH-positive heterozygous cases. In addition, decreased p53 expression was observed more often in the endometrium of patients than in controls.

CONCLUSIONS

p53 SNPs are not associated with endometriosis in Indian women. However, LOH and reduced expression of p53 are related with the risk of endometriosis in Indian women.

The p53 codon 72 polymorphism is associated with risk and early onset of breast cancer among Saudi women

Breast cancer has a major impact on the health of women worldwide. In the Kingdom of Saudi Arabia (KSA), breast cancer incidence is on the increase and is characterized by early onset and aggressiveness. Owing to the importance of the TP53 gene in breast carcinogenesis, we analyzed the possible link between TP53 single nucleotide polymorphisms (SNPs) and the risk of breast cancer in Saudi women by direct sequencing of the TP53 gene exon 4 from 100 breast cancer tissues. The proportion of the polymorphic forms of SNP72 in the Saudi breast cancer patients were: Arg/Arg (RR), 39%; Pro/Pro (PP), 36%; and Arg/Pro (RP), 25%. The frequencies of these forms in disease-free Saudi women were 7.59, 22.22 and 60.19%, respectively. This indicates that the RR form of the codon 72 polymorphism is a potential risk factor, whereas the RP form is a protection factor against breast cancer among Saudi women (p=0.0001). Moreover, the results have shown that the p53 R72P SNP is significantly associated with the early onset of breast cancer in the Saudi population (p=0.0138). However, the codon 47 polymorphism appears to have no role in this disease among Saudi women. These results indicate that the TP53 gene could play a major role in breast carcinogenesis and the early onset of the disease among Saudi women.

Regulation of Fertility by the p53 Family Members

The p53 family members, which consist of 3 transcription factors-p53, p63, and p73-are conserved during evolution. The p53 family proteins are involved in many important cellular functions, including tumor suppression (p53 and p73), the development of epithelial cell layers (p63), and the development of central nervous system and immune system (p73). Studies on p53-like proteins in low organisms have demonstrated that their primordial functions are to maintain the genomic integrity of germ cells and ensure faithful development and reproduction. In vertebrates, the p53 family proteins retain these functions in reproduction and at the same time have developed additional important functions in reproduction, such as the regulation of embryonic implantation (p53). p53 regulates embryonic implantation through transcriptional regulation of leukemia inhibitory factor (LIF). p63, in particular TAp63, is a main regulator to protect the fidelity of female germ cells during meiotic arrest. p73, in particular TAp73, regulates the ovary function and the quality of oocytes. Loss of p53, p63, or p73 genes in female mice leads to a significant decrease in fertility. These functions of the p53 family proteins in reproduction provide a plausible explanation for positive evolutionary selection observed in a group of single nucleotide polymorphisms and haplotypes in the p53 family genes. A better understanding of the functions of the p53 family proteins in reproduction may lead to new strategies for fertility treatment.

The Environmental Polymorphism Registry: a unique resource that facilitates translational research of environmental disease

BACKGROUND

Dissecting complex disease has become more feasible because of the availability of large-scale DNA resources and advances in high-throughput genomic technology. Although these tools help scientists identify potential susceptibility loci, subjects with relevant genotypes are needed for clinical phenotyping and toxicity studies.

OBJECTIVE

We have developed a resource of subjects and their DNA to use for translational research of environmental disease.

METHODS

More than 15,000 individuals of diverse sex, age, race, and ethnicity were recruited from North Carolina. DNA was isolated from their blood and coded with personal identification numbers linked to their identities. This linked resource of subjects and their DNA-the Environmental Polymorphism Registry (EPR)-allows scientists to screen for individuals with genotypes of interest and invite them to participate in follow-up studies.

DISCUSSION

The EPR is a phenotype-by-genotype resource designed to facilitate translational studies of environmental disease. Based on their genotypes, subjects are invited to participate at all levels of research, from basic laboratory ex vivo cell phenotyping experiments that require viable tissue to in vivo observational studies and clinical trials. Here we report on progress of the EPR since 2008. We also describe a major effort at the National Institute of Environmental Health Sciences (NIEHS) to investigate susceptibility loci in 87 environmental response genes and gene × environment interactions using EPR resources.

CONCLUSION

The EPR is a unique and novel resource and is ideal for genotype-driven translational research of environmental disease. We expect that it will serve as a model for future resources. Such tools help scientists attain their ultimate goals: to identify at-risk populations and develop strategies for preventing and treating human disease.

Role of functional polymorphisms of P53 and P73 genes with the risk of prostate cancer in a case-control study from Northern India

BACKGROUND AND AIMS

P53 gene variants BstUI RFLP at codon 72 in exon 4, 16-bp tandem repeat in intron 3 and Msp I RFLP in intron 6 and P73 gene variants of G4C14-to-A4T14 (GC/AT), exon 2 polymorphism, which respectively codes for four functionally different protein isoforms, have been shown to modulate susceptibility to different types of human neoplasms. We undertook this study to evaluate the role of P53 and P73 SNPs in prostate cancer in a Northern Indian population.

METHODS

P53 and P73 genotypes were assessed in a hospital-based case-control study comprised of 177 prostate cancer cases and 265 healthy controls. After the extraction of genomic DNA from blood, genotyping was done using PCR-RFLP and PCR-CTPP methods, respectively.

RESULTS

A significant association was found in P53 intron 6 G>A and P53 R72P G>C polymorphism with PCa risk. In P53 intron 6 G>A polymorphism the heterozygous genotype (GA) showed marginal risk with the disease (OR = 1.48, 95% CI = 0.999-2.220). Individuals with heterozygous genotype only (GC) of P53 R72P G>C polymorphism demonstrated PCa risk (OR = 1.5, 95% CI = 1-2.199). Haplotypes G-C-D and A-G-D (OR = 1.58, 95% CI = 1.125-2.241 and OR = 2.70, 95% CI = 1.767-4.143, respectively) were also found to be associated with an increased risk of PCa.

CONCLUSIONS

Our study provided evidence that the P53 intron 6 G>A and R72P G>C polymorphisms were associated with a higher risk of prostate cancer in a Northern Indian population.

A single-nucleotide polymorphism in TP53 may be a genetic risk factor for Iranian patients with idiopathic male infertility

Male infertility is a heterogeneous disorder that contributes to the impairment of spermatogenesis. The purpose of this study was to assess whether tumour suppressor p53 gene (Tp53) polymorphism is associated with idiopathic male infertility in the Iranian population. The prevalence of G → C substitution at codon 72 in exon 4 was determined in 110 idiopathic infertile azoo-/oligospermic patients and 180 fertile healthy control men. PCR-restriction fragment polymorphism analysis was employed to determine the genotypes. PCR amplicons were subjected to restriction digestion with Bstu1 and separated by gel electrophoresis. The Arg/Arg genotype was found more frequently among men with idiopathic infertility (32.7%) than among controls (17.7%). No significant difference was observed between Pro/Pro genotype and Arg/Arg + Arg/Pro genotypes among men with idiopathic infertility and controls (P = 0.11; OR: 0.36; 95% CI: 0.36-1.10). In contrast, a significant difference was observed in the comparison of the Arg/Arg genotype and Arg/Pro + Pro/Pro genotypes among patients and controls (P = 0.004; OR: 2.25; 95% CI: 1.29-3.90). Allele frequency evaluation suggested a significantly higher incidence of the Arg allele among infertile men compared with controls (56% versus 44%; OR: 1.6; 95% CI: 0.92-2.80). In conclusion, arginine allele appears to be at greater risk of developing idiopathic infertility in Iranian men.

p53 codon 72 polymorphism and recurrent pregnancy loss: a meta-analysis

BACKGROUND

Arg72Pro polymorphism of the p53 tumour suppressor gene have been associated with recurrent pregnancy loss. However, results were inconsistent. We performed this metaanalysis to drive amore precise estimation of association between p53 codon 72 polymorphism and recurrent pregnancy loss.

METHODS

Electronic searche of PubMed was conducted to select studies. Case-control studies containing available genotype frequencies of Arg72Pro were chose, and Odds ratio (OR) with 95% confidence interval (CI) was used to assess the strength of this association.

RESULTS

4 case-control studies including 523 cases and 378controls were identified. This meta-analysis showed that individuals with the homozygous Pro/Pro genotype had increased risk of recurrent pregnancy loss (OR = 1.85, 95% CI: 1.078 ~ 3.173, p = 0.025) in the pooled analyses. An symmetric funnel plot, the Egger's test (P = 0.497), and the Begg- test (P = 0.85) were all suggestive of the lack of publication bias.

CONCLUSION

This meta-analysis supports the idea that p53 condon72 Pro/Pro genotype is associated with increased risk of recurrent pregnancy loss. To draw comprehensive and true conclusions, further prospective studies with larger numbers of participants worldwide are needed to examine associations between p53 codon 72 polymorphism and recurrent pregnancy loss.

Mitochondrial superoxide dismutase--signals of distinction

Mitochondrial superoxide dismutase (MnSOD) neutralizes the highly reactive superoxide radical (O(2)(˙-)), the first member in a plethora of mitochondrial reactive oxygen species (ROS). Over the past decades, research has extended the prevailing view of mitochondrion well beyond the generation of cellular energy to include its importance in cell survival and cell death. In the normal state of a cell, endogenous antioxidant enzyme systems maintain the level of reactive oxygen species generated by the mitochondrial respiratory chain. Mammalian mitochondria are important to the production of reactive oxygen species, which underlie oxidative damage in many pathological conditions and contribute to retrograde redox signaling from the organelle to the cytosol and nucleus. Mitochondria are further implicated in various metabolic and aging-related diseases that are now postulated to be caused by misregulation of physiological systems rather than pure accumulation of oxidative damage. Thus, the signaling mechanisms within mitochondria, and between the organelle and its environment, have gained interest as potential drug targets. Here, we discuss redox events in mitochondria that lead to retrograde signaling, the role of redox events in disease, and their potential to serve as therapeutic targets.

Complement polymorphisms: geographical distribution and relevance to disease

The evolution of man has been characterised by recurrent episodes of migration and settlement with infectious disease a constant threat. This long history of demographic change, together with the action of evolutionary forces such as natural selection and genetic drift, has shaped human genetic diversity. In particular, the interaction between humans, pathogens and the environment has played a crucial role in generating patterns of human genetic variation. The complement system plays a crucial role in the early protective immune response after exposure to a pathogen. Pathogens, over time, have developed mechanisms to circumvent the effects of complement which in turn has led to development of a more complex complement system. During the evolution of the complement system genes coding complement proteins have evolved polymorphisms, some of which have a functional effect, and this may reflect human-pathogen interaction and geographical origin. An example is the polymorphism Ile62Val (rs800292 (A>G)) in the complement regulator Factor H gene which alters the susceptibility to age-related macular degeneration (AMD), with the Ile62 polymorphism protecting against AMD. When sub-Saharan African and European populations are compared, the frequency of this polymorphism shows a very marked geographical distribution. Polymorphisms in other complement genes such as complement factor B show similar trends. This paper describes the geographical variation present in complement genes and discusses the implications of these observations. The analysis of genetic variation in complement genes is a promising tool to unravel mechanisms of host-pathogen interaction and can provide new insights into the evolution of the human immune system.

P53 codon 72 (Arg72Pro) polymorphism and prostate cancer risk: association between disease onset and proline genotype

The tumor suppressor gene p53 plays an important role in the stress response of the cell and is mutated in 50% of all human tumors. The p53 Arg72Pro single-nucleotide polymorphism (SNP) was found to be associated with an increased risk of various malignancies. Biochemical and biological differences between the 2 polymorphic variants of wild-type P53 might lead to distinct susceptibility to HPV- and non-HPV-induced tumors. For prostate cancer, only limited data are available, especially in the Caucasian population. Therefore, we determined the distribution of the Arg72Pro SNP in a Caucasian case-control study including 118 prostate cancer patients and 194 male controls without any malignancy using restriction fragment length polymorphism analysis. A subset of 33 tumors was tested for HPV infection, and no HPV DNA was found. Cases and controls showed similar distributions of alleles in the SNP (p = 0.720). Regarding the onset of the disease, patients diagnosed at ≤60 years of age and older patients (>60 years of age) showed a significant difference in genotype distribution (p = 0.035); there was also an increased occurrence of risk allele Pro72 in cases aged ≤60 years (p = 0.045). A subset of 64 prostate tumors was stained immunohistochemically for P53. 5 of 64 prostate tumors (7.8%) were positive for P53 expression, indicating integrity of the protein in the majority of cases. Genotype distribution showed no association with the Gleason score or additional histopathological characteristics. This study shows that the overall risk of prostate cancer was not associated with Arg72Pro SNP and HPV infection in our cohort. However, disease onset might be modulated by the p53 Pro72 allele, suggesting an important role of apoptosis regulation in prostate carcinogenesis.

p53 codon 72 polymorphism is associated with susceptibility to hepatocellular carcinoma in the Turkish population: a case-control study

The tumor suppressor p53 gene plays a crucial role in preventing carcinogenesis through its ability to induce cell cycle arrest and apoptosis following DNA damage and oncogene activation. A guanine (G)/cytosine (C) common single nucleotide polymorphism (SNP) at second position of codon 72 in exon 4 of p53 gene determines a arginine (Arg) to proline (Pro) (Arg72Pro) aminoacidic substitution within the proline-rich domain of p53 protein. Arg72 and Pro72 allele are different from a biochemical and biological point of view and many reports suggest that they can modulate individual cancer susceptibility. To determine the association of the p53 Arg72Pro polymorphism with the risk of hepatocellular carcinoma (HCC) development in a Turkish population, a hospital-based case-control study was designed consisting of 119 subjects with HCC and 119 cancer-free control subjects matched for age, gender, smoking and alcohol status. The genotype frequency of the p53 Arg72Pro polymorphism was determined by using a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay. Our data shows that the Pro/Pro genotype of the p53 Arg72Pro polymorphism is associated with increased risk of HCC development in this Turkish population (OR = 3.20, 95% CI: 1.24-8.22, P = 0.02). Furthermore, according to stratified analysis, a significant association was observed between the homozygote Pro/Pro genotype and HCC risk in the subgroups of male gender (OR = 3.01, 95% CI: 1.14-7.97, P = 0.03) and patients with hepatitis B virus (HBV)-related HCC (OR = 4.04, 95% CI: 1.46-11.15, P = 0.007). Because our results suggest for the first time that the Pro/Pro homozygote of p53 Arg72Pro polymorphism may be a genetic susceptibility factor for HCC (especially in the male gender and HBV-infected patients) in the Turkish population, further independent studies are required to validate our findings in a larger series, as well as in patients of different ethnic origins.

Cycloheximide suppresses radiation-induced apoptosis in MOLT-4 cells with Arg72 variant of p53 through translational inhibition of p53 accumulation

The human T-cell leukemia cell line MOLT-4 is highly radiosensitive, and thus it is often used as a model of p53-dependent radiation-induced apoptosis. Two branches of the p53-mediated apoptotic pathway are reported: "transcription-dependent" and "transcription-independent." However, the relative contribution of each in different types of cells is not yet clearly defined. Moreover, recent studies have shown that the codon 72 polymorphic variants of p53 show different sensitivities to apoptosis signals. The Arg72 variant has a more potent apoptosis-inducing activity in mitochondria than the Pro72 variant. Here, we initially investigated the codon 72 polymorphism of p53 in MOLT-4 cells. Analysis of the p53 exon 4 genomic DNA sequence, which includes codon 72, revealed that MOLT-4 cells are homozygous for the allele encoding Arg72. We next investigated the involvement of the transcription-independent function of p53 using an RNA synthesis inhibitor, actinomycin D (ActD), and a protein synthesis inhibitor, cycloheximide (CHX), and found that the apoptosis was suppressed by CHX but not by ActD. We also revealed that the suppressive effect of CHX on apoptosis was specifically mediated by p53, using a p53-knockdown MOLT-4 transfectant. Furthermore, the suppressive effect of CHX on apoptosis was highly correlated with the suppression of p53 protein accumulation, and less correlated with the suppression of p53 target genes expression. These results indicated that p53 transactivation is not necessary to induce apoptosis, and that p53 protein accumulation itself is both necessary and sufficient to do so.

Cancer susceptibility polymorphism of p53 at codon 72 affects phosphorylation and degradation of p53 protein

The common polymorphism of p53 at codon 72, either encoding proline or arginine, has drawn attention as a genetic factor associated with clinical outcome or cancer risk for the last 2 decades. We now show that these two polymorphic variants differ in protein structure, especially within the N-terminal region and, as a consequence, differ in post-translational modification at the N terminus. The arginine form (p53-72R) shows significantly enhanced phosphorylation at Ser-6 and Ser-20 compared with the proline form (p53-72P). We also show diminished Mdm2-mediated degradation of p53-72R compared with p53-72P, which is at least partly brought about by higher levels of phosphorylation at Ser-20 in p53-72R. Furthermore, enhanced p21 expression in p53-72R-expressing cells, which is dependent on phosphorylation at Ser-6, was demonstrated. Differential p21 expression between the variants was also observed upon activation of TGF-β signaling. Collectively, we demonstrate a novel molecular difference and simultaneously suggest a difference in the tumor-suppressing function of the variants.

Regulation of female reproduction by p53 and its family members

Tumor suppressor p53 is crucial for embryonic implantation through transcriptional up-regulation of uterine leukemia inhibitory factor (LIF). This article reports that p53 and estrogen receptor α were activated in endometrial tissues during implantation to coordinately regulate LIF production. By using human p53 knockin (Hupki) mice carrying a single nucleotide polymorphism (SNP) at codon 72 (arginine/proline), the arginine allele was demonstrated to produce higher uterine LIF levels during implantation than the proline allele. In humans, the diversity of haplotypes of the p53 gene has decreased during evolution, because the arginine allele, existing in only a subset of haplotypes, is under positive selection. This observation is consistent with previous results showing that the proline allele is enriched in patients undergoing in vitro fertilization (IVF). Studies with p63- and p73-knockout mice have demonstrated the involvement of p63 and p73 in female reproduction and their roles in egg formation and apoptosis (p63) and spindle checkpoint (p73) in female mice. Here, the role of p63 and p73 in human reproduction was investigated. Selected alleles of SNPs in p63 and p73 genes were enriched in IVF patients. These findings demonstrate that the p53 family members are involved in several steps to regulate female reproduction in mice and humans.

Molecular adaptation of modern human populations

Modern humans have gone through varied processes of genetic adaptations when their ancestors left Africa about 100,000 years ago. The environmental stresses and the social transitions (e.g., emergence of the Neolithic culture) have been acting as the major selective forces reshaping the genetic make-up of human populations. Genetic adaptations have occurred in many aspects of human life, including the adaptation to cold climate and high-altitude hypoxia, the improved ability of defending infectious diseases, and the polished strategy of utilizing new diet with the advent of agriculture. At the same time, the adaptations once developed during evolution may sometimes generate deleterious effects (e.g., susceptibility to diseases) when facing new environmental and social changes. The molecular (especially the genome-wide screening of genetic variations) studies in recent years have detected many genetic variants that show signals of Darwinian positive selection in modern human populations, which will not only provide a better understanding of human evolutionary history, but also help dissecting the genetic basis of human complex diseases.

p53 Pro72Arg polymorphism and prostate cancer in men of African descent

BACKGROUND

p53 is a transcription factor that regulates the cell cycle, DNA repair, and apoptosis. A variant at codon 72, rs1042522, results in altered activities for p53 and is, notably, differentially distributed among different ethnic populations. However, associations of this variant with cancer in men of African descent have not been explored. Herein, we tested the hypothesis that rs1042522 was associated with prostate cancer (PCa) risk.

MATERIALS AND METHODS

Genotypes were determined by PCR-RFLP methods in a study population of African descent consisting of 266 PCa patients and 196 male controls.

RESULTS

Our results indicate that the p53 polymorphism may be associated with increased risk of PCa. Genotypes were significantly and marginally associated with PCa risk using the dominant and log-additive genetic models (OR=1.53, 95% CI: 1.02-2.29, P=0.04; OR=1.33, 95% CI: 0.99-1.78, P=0.06, respectively). After adjusting for age, the associations with PCa remained, but results were not statistically significant (OR=1.48, 95% CI: 0.95-2.31, P=0.08; OR=1.30, 95% CI: 0.95-1.80, P=0.10, respectively).

CONCLUSIONS

The present study demonstrates that population-dependent differences in allele frequencies associated with health disparities provide a valuable framework for the interrogation of complex diseases in all populations.

Dealing with mentally ill domestic violence perpetrators: A therapeutic jurisprudence judicial model

People suffering from mental illness are increasingly referred to the domestic violence court. Yet the typical diversion programs available, including batterer's intervention programs, are inappropriate for those with serious mental illness. As a result, the Miami-Dade Domestic Violence Court has developed a new approach for dealing with this population that applies mental health court techniques in domestic violence court. This article will describe and discuss this pioneering model. It also will situate this model within the context of other problem-solving courts and discuss how the court uses principles and approaches of therapeutic jurisprudence. The paper presents some preliminary data that describe the social and legal characteristics of 20 defendants in the Domestic Violence Mental Health Court followed over a two year period between 2005 and 2007.

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.