Variation in the human TP53 gene affects old age survival and cancer mortality

Understanding the complexity of p53 in a new era of tumor suppression

p53 was discovered 45 years ago as an SV40 large T antigen binding protein, coded by the most frequently mutated TP53 gene in human cancers. As a transcription factor, p53 is tightly regulated by a rich network of post-translational modifications to execute its diverse functions in tumor suppression. Although early studies established p53-mediated cell-cycle arrest, apoptosis, and senescence as the classic barriers in cancer development, a growing number of new functions of p53 have been discovered and the scope of p53-mediated anti-tumor activity is largely expanded. Here, we review the complexity of different layers of p53 regulation, and the recent advance of the p53 pathway in metabolism, ferroptosis, immunity, and others that contribute to tumor suppression. We also discuss the challenge regarding how to activate p53 function specifically effective in inhibiting tumor growth without harming normal homeostasis for cancer therapy.

The role of longevity-related genetic variant interactions as predictors of survival after 85 years of age

Genome-wide association studies and candidate gene studies have identified several genetic variants that might play a role in achieving longevity. This study investigates interactions between pairs of those single nucleotide polymorphisms (SNPs) and their effect on survival above the age of 85 in a sample of 327 Croatian individuals. Although none of the SNPs individually showed a significant effect on survival in this sample, 14 of the 359 interactions tested (between SNPs not in LD) reached the level of nominal significance (p<0.05), showing a potential effect on late-life survival. Notably, SH2B3 rs3184504 interacted with different SNPs near TERC, TP53 rs1042522 with different SNPs located near the CDKN2B gene, and CDKN2B rs1333049 with different SNPs in FOXO3, as well as with LINC02227 rs2149954. The other interaction pairs with a possible effect on survival were FOXO3 rs2802292 and ERCC2 rs50871, IL6 rs1800795 and GHRHR rs2267723, LINC02227 rs2149954 and PARK7 rs225119, as well as PARK7 rs225119 and PTPN1 rs6067484. These interactions remained significant when tested together with a set of health-related variables that also had a significant effect on survival above 85 years. In conclusion, our results confirm the central role of genetic regulation of insulin signalling and cell cycle control in longevity.

A Network Pharmacology-based Study on the Anti-aging Properties of Traditional Chinese Medicine Sisheng Bulao Elixir

BACKGROUND

Traditional Chinese Medicine (TCM) has a rich history of use in preventing senescence for millennia in China. Nonetheless, a systematic method to study the antiaging properties and the underlying molecular mechanism of TCM remains absent.

OBJECTIVE

The objective of this study is to decipher the anti-aging targets and mechanisms of Sisheng Bulao Elixir (SBE) using a systematic approach based on a novel aging database and network pharmacology.

METHODS

Bioactive compounds and target proteins in SBE were identified via the Traditional Chinese Medicine System Pharmacology (TCMSP) database. Aging-related proteins were uncovered through alignment with the Ageing Alta database. A compound-target (CT) protein network analysis highlighted key flavonoids targeting aging. Core aging-related proteins were extracted through protein-protein interaction (PPI) network analysis. Molecular docking validated binding activities between core compounds and aging-related proteins. The antioxidant activity of SBE was confirmed using an in vitro senescent cells model.

RESULTS

A total of 39 active compounds were extracted from a pool of 639 compounds in SBE. Through a matching process with the Aging Alta, 88 target proteins associated with the aging process were identified. Impressively, 80 out of these 88 proteins were found to be targeted by flavonoids. Subsequently, an analysis using CT methodology highlighted 11 top bioactive flavonoids. Notably, core aging-related proteins, including AKT1, MAPK3, TP53, VEGFA, IL6, and HSP90AA1, emerged through the PPI network analysis. Moreover, three flavonoids, namely quercetin, kaempferol, and luteolin, exhibited interactions with over 100 aging-related proteins. Molecular docking studies were conducted on these flavonoids with their shared three target proteins, namely AKT1, HSP90AA1, and IL6, to assess their binding activities. Finally, the antioxidant properties of SBE were validated using an in vitro model of senescent cells.

CONCLUSION

This study offers novel insights into SBE's anti-aging attributes, providing evidence of its molecular mechanisms. It enhances our understanding of traditional remedies in anti-aging research.

Genetic scores for predicting longevity in the Croatian oldest-old population

Longevity is a hallmark of successful ageing and a complex trait with a significant genetic component. In this study, 43 single nucleotide polymorphisms (SNPs) were chosen from the literature and genotyped in a Croatian oldest-old sample (85+ years, sample size (N) = 314), in order to determine whether any of these SNPs have a significant effect on reaching the age thresholds for longevity (90+ years, N = 212) and extreme longevity (95+ years, N = 84). The best models were selected for both survival ages using multivariate logistic regression. In the model for reaching age 90, nine SNPs explained 20% of variance for survival to that age, while the 95-year model included five SNPs accounting for 9.3% of variance. The two SNPs that showed the most significant association (p ≤ 0.01) with longevity were TERC rs16847897 and GHRHR rs2267723. Unweighted and weighted Genetic Longevity Scores (uGLS and wGLS) were calculated and their predictive power was tested. All four scores showed significant correlation with age at death (p ≤ 0.01). They also passed the ROC curve test with at least 50% predictive ability, but wGLS90 stood out as the most accurate score, with a 69% chance of accurately predicting survival to the age of 90.

The Role of TP53 in Adaptation and Evolution

The TP53 gene is a major player in cancer formation, and it is considered the most important tumor suppressor gene. The p53 protein acts as a transcription factor, and it is involved in DNA repair, senescence, cell-cycle control, autophagy, and apoptosis. Beyond cancer, there is evidence that TP53 is associated with fertility, aging, and longevity. Additionally, more evidence exists that genetic variants in TP53 are associated with environmental adaptation. Special TP53 amino-acid residues or pathogenic TP53 mutations seem to be adaptive for animals living in hypoxic and cold environments or having been exposed to starvation, respectively. At the somatic level, it has recently been proven that multiple cancer genes, including TP53, are under positive selection in healthy human tissues. It is not clear why these driver mutations do not transform these tissues into cancerous ones. Other studies have shown that elephants have multiple TP53 copies, probably this being the reason for the very low cancer incidence in these large animals. This may explain the famous Peto's paradox. This review discusses in detail the multilevel role of TP53 in adaptation, according to the published evidence. This role is complicated, and it extends from cells to individuals and to populations.

Investigating the association between cancer and dementia risk: a longitudinal cohort study

BACKGROUND

Previous studies found that cancer survivors had a reduced risk of dementia compared with the general population. However, these findings were uncertain because of survivor bias and a lack of stratification by cancer types. This current cohort study used data from the UK Biobank to explore these associations.

METHODS

Multivariable Cox regression analyses were used to examine the association of cancer status and the risk of dementia with its subtypes after adjusting for age and sex. Hazard ratios (HRs) with 95% confidence intervals (CIs) were calculated as a measure of relative risk by comparing observed dementia incidence among cancer patients.

RESULTS

We included 263,151 participants in the observational analysis. During a median follow-up of 9.18 years, dementia was diagnosed in 472 individuals with cancer and 3685 individuals without cancer, respectively. Cancer patients had lower risks of dementia (hazard ratio: 0.89, confidence interval: 0.81-0.98) and its subtypes (Alzheimer's disease [AD]: 0.85 [0.74-0.98]; vascular dementia [VD]: 0.81 [0.66-0.99]) in the Cox regression adjusted for age and sex. Individuals with cancers in the male genital system had substantially reduced risks of dementia (0.66 [0.46-0.93]) and AD (0.53 [0.29-0.97]) than those with cancers in other systems. Moreover, non-melanoma skin cancer and prostate cancer were associated with a reduced risk of dementia (0.79 [0.62-0.99]; 0.69 [0.49-0.97]), but not with AD or VD (P>0.05).

CONCLUSIONS

The current study supported a negative association between cancer and dementia risk, and encourages further exploration of the mechanistic basis of this inverse relationship to improve understanding.

Clinical Status, Nutritional Behavior, and Lifestyle, and Determinants of Community Well-Being of Patients from the Perspective of Physicians: A Cross-Sectional Study of Young Older Adults, Nonagenarians, and Centenarians in Salerno and Province, Italy

Longevity is rightly considered one of the greatest achievements of modern society. Biomedical research has shown that aging is the major risk factor for many diseases, so to find the right answers to aging it is necessary to identify factors that can positively influence longevity. This study investigated the clinical status, nutritional behavior, lifestyle, and social and community determinants of the well-being of young older adults and nonagenarians/centenarians in Salerno and province through the judgment of their physicians. Data were collected through an online survey. Multivariate Poisson and logistic regression models were used to calculate significant predictors of the outcomes of interest. The interesting finding was that cardiovascular disease was a risk factor for young older adults, while it was a protective factor for nonagenarians/centenarians, meaning that as age increased, heart problems tended to decrease. Certain foods were found to be a significant protective factor for both young older adult and nonagenarian-centenarian patients. In addition, psychosomatic disorders were found to be determinant for the young older adults, while depression was a risk factor for the nonagenarians/centenarians because they were not always gratified by their long lives and often felt like a burden on the family. The protective significant variable among the determinants of community well-being for both young older adults and nonagenarians/centenarians was the retention of honorary achievement. Based on our results, we are able to support the hypothesis of a difference between the young older adults and the nonagenarians/centenarians in clinical status, nutritional behaviors, lifestyle, and determinants of community well-being. However, societies need more social and educational programs that are able to build "a new idea of old age" by improving and supporting the young older adults and the nonagenarians/centenarians, with the goal of intergenerational solidarity, well-being, and social inclusion, as well as preventive interventions on lifestyles and nutrition, which will allow us to provide a new key to understanding aging.

TP53 Mutant Versus Wild-Type Zebrafish Larvae Under Starvation Stress: Larvae Can Live Up to 17 Days Post-Fertilization Without Food

In this study, an experimental protocol has been developed for comparing survival rates of mutant and wild-type zebrafish larvae under extreme starvation. Zebrafish larvae were placed in 96-well plates at fourth day postfertilization (dpf) and larvae were not fed at all from hatching to cease. Zdf1 zebrafish line was used, a strain carrying the (cancer) pathogenic TP53-M214K amino acid substitution. TP53-M214 corresponds to the human TP53-M246 and both residues are located on the DNA-binding domain of the p53 protein. Survival statistical analysis did not show any significant difference in the overall survival rates between homozygous mutant and wild-type larvae. When considering 15 dpf as the endpoint of the experiment (66% of larvae died), a borderline statistical significance was observed for the dominant model of inheritance (p = 0.015; relative hazard = 0.8320). Despite the fact yolk sac of larvae is depleted at 7-8 dpf, 34% of larvae survive until 15 dpf and 1.5% until 17 dpf. Concluding, three main results derive from this study: (1) pathogenic homozygous mutations in TP53 probably do not alter survival rates of zebrafish larvae under starvation; (2) zebrafish larvae can live up to 17 dpf without food, surviving only with their initial nutritional supplies; and (3) an easy and affordable protocol has been developed for estimating survival rates of zebrafish larvae under stressful conditions.

Evolutionarily conserved transcription factors as regulators of longevity and targets for geroprotection

Aging is the single largest risk factor for many debilitating conditions, including heart diseases, stroke, cancer, diabetes, and neurodegenerative disorders. While far from understood in its full complexity, it is scientifically well-established that aging is influenced by genetic and environmental factors, and can be modulated by various interventions. One of aging's early hallmarks are aberrations in transcriptional networks, controlling for example metabolic homeostasis or the response to stress. Evidence in different model organisms abounds that a number of evolutionarily conserved transcription factors, which control such networks, can affect lifespan and healthspan across species. These transcription factors thus potentially represent conserved regulators of longevity and are emerging as important targets in the challenging quest to develop treatments to mitigate age-related diseases, and possibly even to slow aging itself. This review provides an overview of evolutionarily conserved transcription factors that impact longevity or age-related diseases in at least one multicellular model organism (nematodes, flies, or mice), and/or are tentatively linked to human aging. Discussed is the general evidence for transcriptional regulation of aging and disease, followed by a more detailed look at selected transcription factor families, the common metabolic pathways involved, and the targeting of transcription factors as a strategy for geroprotective interventions.

Genes and Longevity of Lifespan

Aging is a complex process indicated by low energy levels, declined physiological activity, stress induced loss of homeostasis leading to the risk of diseases and mortality. Recent developments in medical sciences and an increased availability of nutritional requirements has significantly increased the average human lifespan worldwide. Several environmental and physiological factors contribute to the aging process. However, about 40% human life expectancy is inherited among generations, many lifespan associated genes, genetic mechanisms and pathways have been demonstrated during last decades. In the present review, we have evaluated many human genes and their non-human orthologs established for their role in the regulation of lifespan. The study has included more than fifty genes reported in the literature for their contributions to the longevity of life. Intact genomic DNA is essential for the life activities at the level of cell, tissue, and organ. Nucleic acids are vulnerable to oxidative stress, chemotherapies, and exposure to radiations. Efficient DNA repair mechanisms are essential for the maintenance of genomic integrity, damaged DNA is not replicated and transferred to next generations rather the presence of deleterious DNA initiates signaling cascades leading to the cell cycle arrest or apoptosis. DNA modifications, DNA methylation, histone methylation, histone acetylation and DNA damage can eventually lead towards apoptosis. The importance of calorie restriction therapy in the extension of lifespan has also been discussed. The role of pathways involved in the regulation of lifespan such as DAF-16/FOXO (forkhead box protein O1), TOR and JNK pathways has also been particularized. The study provides an updated account of genetic factors associated with the extended lifespan and their interactive contributory role with cellular pathways.

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.

The Changes in the p53 Protein across the Animal Kingdom Point to Its Involvement in Longevity

Recently, the quest for the mythical fountain of youth has produced extensive research programs that aim to extend the healthy lifespan of humans. Despite advances in our understanding of the aging process, the surprisingly extended lifespan and cancer resistance of some animal species remain unexplained. The p53 protein plays a crucial role in tumor suppression, tissue homeostasis, and aging. Long-lived, cancer-free African elephants have 20 copies of the TP53 gene, including 19 retrogenes (38 alleles), which are partially active, whereas humans possess only one copy of TP53 and have an estimated cancer mortality rate of 11–25%. The mechanism through which p53 contributes to the resolution of the Peto’s paradox in Animalia remains vague. Thus, in this work, we took advantage of the available datasets and inspected the p53 amino acid sequence of phylogenetically related organisms that show variations in their lifespans. We discovered new correlations between specific amino acid deviations in p53 and the lifespans across different animal species. We found that species with extended lifespans have certain characteristic amino acid substitutions in the p53 DNA-binding domain that alter its function, as depicted from the Phenotypic Annotation of p53 Mutations, using the PROVEAN tool or SWISS-MODEL workflow. In addition, the loop 2 region of the human p53 DNA-binding domain was identified as the longest region that was associated with longevity. The 3D model revealed variations in the loop 2 structure in long-lived species when compared with human p53. Our findings show a direct association between specific amino acid residues in p53 protein, changes in p53 functionality, and the extended animal lifespan, and further highlight the importance of p53 protein in aging.

Cancer and Tumour Suppressor p53 Encounters at the Juncture of Sex Disparity

There are many differences in cancer manifestation between men and women. New understanding of the origin of these point to fundamental distinctions in the genetic code and its demise. Tumour suppressor protein p53 is the chief operating officer of cancer defence and critically acts to safeguard against sustained DNA damaged. P53 cannot be ignored in cancer sex disparity. In this review we discuss the greater prevalence and associated death rates for non-reproductive cancers in males. The major tumour suppressor protein p53, encoded in the TP53 gene is our chosen context. It is fitting to ask why somatic TP53 mutation incidence is estimated to be disproportionately higher among males in the population for these types of cancers compared with females? We scrutinised the literature for evidence of predisposing genetic and epigenetic alterations that may explain this sex bias. Our second approach was to explore whether redox activity, either externally imposed or inherent to males and females, may define distinct risks that could contribute to the clear cancer sex disparities.

Cancer and Alzheimer's disease inverse relationship: an age-associated diverging derailment of shared pathways

Several epidemiological studies show an inverse association between cancer and Alzheimer's disease (AD). It is debated whether this association is the consequence of biological mechanisms shared by both these conditions or may be related to the pharmacological treatments carried out on the patients. The latter hypothesis, however, is not sustained by the available evidence. Hence, the focus of this review is to analyze common biological mechanisms for both cancer and AD and to build up a biological theory useful to explain the inverse correlation between AD and cancer. The review proposes a hypothesis, according to which several molecular players, prominently PIN1 and p53, have been investigated and considered involved in complex molecular interactions putatively associated with the inverse correlation. On the other hand, p53 involvement in both diseases seems to be a consequence of the aberrant activation of other proteins. Instead, PIN1 may be identified as a novel key regulator at the crossroad between cancer and AD. PIN1 is a peptidyl-prolyl cis-trans isomerase that catalyzes the cis-trans isomerization, thus regulating the conformation of different protein substrates after phosphorylation and modulating protein function. In particular, trans-conformations of Amyloid Precursor Protein (APP) and tau are functional and "healthy", while cis-conformations, triggered after phosphorylation, are pathogenic. As an example, PIN1 accelerates APP cis-to-trans isomerization thus favoring the non-amyloidogenic pathway, while, in the absence of PIN1, APP is processed through the amyloidogenic pathway, thus predisposing to neurodegeneration. Furthermore, a link between PIN1 and tau regulation has been found, since when PIN1 function is inhibited, tau is hyperphosphorylated. Data from brain specimens of subjects affected by mild cognitive impairment and AD have revealed a very low PIN1 expression. Moreover, polymorphisms in PIN1 promoter correlated with an increased PIN1 expression are associated with a delay of sporadic AD age of onset, while a polymorphism related to a reduced PIN1 expression is associated with a decreased risk of multiple cancers. In the case of dementias, in particular of Alzheimer's disease, new biological markers and targets based on the discussed players can be developed based on a theoretical approach relying on different grounds compared to the past. An unbiased expansion of the rationale and of the targets may help to achieve in the field of neurodegenerative dementias similar advances to those attained in the case of cancer treatment.

Genetic variation in APOE, GRN, and TP53 are phenotype modifiers in frontotemporal dementia

Frontotemporal dementia (FTD) is a clinical, genetic, and pathologic heterogeneous group of neurodegenerative diseases. In this study, we investigated the role of APOƐ4, rs5848 in GRN, and rs1042522 in TP53 gene as disease risk factors and/or phenotype modifiers in 440 FTD patients, including 175 C9orf72 expansion carriers. We found that the C9orf72 expansion carriers showing an earlier age at onset (p < 0.001). Among the clinical groups, the FTD-MND (motoneuron disease) showed the lowest survival (hazard ratio [HR] = 4.12), and the progressive nonfluent aphasia group showed the highest onset age (p = 0.03). In our cohort, the rs1042522 in TP53 was associated with disease onset (p = 0.02) and survival (HR = 1.73) and rs5848 GRN with a significantly shorter survival in CC homozygous patients (HR = 1.98). The frequency of APOƐ4 carriers was significantly increased in the C9orf72 noncarriers (p = 0.022). Although validation of our findings is necessary, our results suggest that TP53, GRN, and APOE genes may act as phenotype modifiers in FTD and should be considered in future clinical trials.

Peroxisome Metabolism in Cancer

Peroxisomes are metabolic organelles involved in lipid metabolism and cellular redox balance. Peroxisomal function is central to fatty acid oxidation, ether phospholipid synthesis, bile acid synthesis, and reactive oxygen species homeostasis. Human disorders caused by genetic mutations in peroxisome genes have led to extensive studies on peroxisome biology. Peroxisomal defects are linked to metabolic dysregulation in diverse human diseases, such as neurodegeneration and age-related disorders, revealing the significance of peroxisome metabolism in human health. Cancer is a disease with metabolic aberrations. Despite the critical role of peroxisomes in cell metabolism, the functional effects of peroxisomes in cancer are not as well recognized as those of other metabolic organelles, such as mitochondria. In addition, the significance of peroxisomes in cancer is less appreciated than it is in degenerative diseases. In this review, I summarize the metabolic pathways in peroxisomes and the dysregulation of peroxisome metabolism in cancer. In addition, I discuss the potential of inactivating peroxisomes to target cancer metabolism, which may pave the way for more effective cancer treatment.

Evolutionary Conservation of Transcription Factors Affecting Longevity

The increasing number of older people is resulting in an increased prevalence of age-related diseases. Research has shown that the ageing process itself is a potential point of intervention. Indeed, gene expression can be optimised for health in older ages through manipulation of transcription factor (TF) activity. This review is focused on the ever-growing number of TFs whose effects on ageing are evolutionarily conserved. These regulate a plethora of functions, including stress resistance, metabolism, and growth. They are engaged in complex interactions within and between different cell types, impacting the physiology of the entire organism. Since ageing is not programmed, the conservation of their effects on lifespan is most likely a reflection of the conservation of their functions in youth.

Effect of maternal HIV infection, BMI and NOx air pollution exposure on birth outcomes in South African pregnant women genotyped for the p53 Pro72Arg (rs1042522)

Tumour suppressor protein, p53, plays a role in modulating innate immune responses, DNA repair, cell cycle arrest, senescence and apoptosis. Maternal nitrogen oxide (NOx) air pollution exposure, body mass index (BMI), human immunodeficiency virus (HIV) infection and p53 Pro72Arg (rs1042522) affect foetal growth. We investigated whether the aforementioned factors influence birth outcomes in a South African population. Pregnant women (n = 300; HIV -ve = 194 and HIV +ve = 106) were genotyped for the p53 rs1042522 using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), and further stratified based on HIV status, infants' birthweight (BW; NBW: normal BW [>2,500 g] and LBW: low BW [<2,500 g]) and gestational age (GA; NGA: normal GA [>37 weeks] and PTB: preterm birth [≤37 weeks]). A land use regression model was developed to characterize maternal NOx exposure. Pearson's correlation and multivariate regression analysis statistical tests were used to determine the effect of rs1042522 genotyped pregnant women's BMI and NOx exposure on maternal blood pressure and haemoglobin and iron levels, and infants' anthropometric measurements and Appearance Pulse Grimace Activity and Respiration (APGAR) scores. The prevalence of LBW and PTB was 14.7% and 18.7%, respectively. The LBW group had a higher frequency of the variant Arg-allele versus NBW group (47.7% vs. 31.4%, p = .0046, OR = 2.0, 95% CI = 1.26-3.17). No association was observed between NGA and PTB groups. A significant association between BMI and systolic blood pressure (r = .50, p = .00; B = 0.76, p = .002) and birth length (r = -.28, p = .01; B = -0.107, p = .011), and NOx and birth length (r = -.26, p = .08; B = -0.191, p = .046) and birthweight (B = -8.87, p = .048) was observed in HIV-infected mothers with the variant Pro/Arg + Arg/Arg genotypes. Mothers from the LBW group with the variant genotypes displayed an association between NOx and diastolic blood pressure (r = .58, p = .04), blood iron levels (r = -.60, p = .04; B = -0.204, p = .004), APGAR scores at 1 min (r = -.86, p = .00; B = -0.101, p = .003) and 5 min (r = -.75, p = .01) and birth length (r = -.61, p = .04), and BMI and diastolic blood pressure (r = .72, p = .01). In the PTB group, maternal variant genotypes and NOx were associated with blood haemoglobin levels (B = -0.132, p = .045) and APGAR scores at 1 min (B = -0.161, p = .045) and 5 min (B = -0.147, p = .043). Maternal rs1042522 Arg-allele, HIV infection, BMI and NOx exposure collectively play a role in lowering blood iron levels, gestational hypertension and LBW outcomes.

The Association Between Cancer and Dementia: A National Cohort Study in Sweden

Background: Previous studies have found that the incidence of dementia is lower in patients with cancer. However, the impact of survival bias, as well as the confounding by medical treatment, have not been fully addressed. We aimed to explore the subsequent risk of dementia in different follow-up intervals among patients with cancer, as well as the risk before the diagnosis of cancer. Methods: By using the Swedish Cancer Register and the Swedish Hospital Discharge Register, we systematically examined the risk of dementia among patients diagnosed with 35 different types of cancer. Standardized incidence ratios (SIRs) were used to calculate the relative risk. Results: The subsequent risk of dementia in patients with cancer decreased by 21% compared to matched cancer-free controls (SIR = 0.79, 95% CI 0.78-0.80). For specific cancer sites, 21 of them had a significantly lower risk of subsequent dementia. The decreased risk of dementia was also significant before the diagnosis of cancer. However, the risk was higher among patients with cancer who survived for more than 10 years' post-diagnosis (SIR = 1.37, 95% CI 1.32-1.41). Conclusions: In this population-based study, we found that the risk of dementia was lower among patients with cancer, and the risk was also lower before the diagnosis of cancer. This suggests that lower dementia risk is not simply due to bias. However, the underlying mechanisms need to be explored further.

Longevity: Lesson from Model Organisms

Research on longevity and healthy aging promises to increase our lifespan and decrease the burden of degenerative diseases with important social and economic effects. Many aging theories have been proposed, and important aging pathways have been discovered. Model organisms have had a crucial role in this process because of their short lifespan, cheap maintenance, and manipulation possibilities. Yeasts, worms, fruit flies, or mammalian models such as mice, monkeys, and recently, dogs, have helped shed light on aging processes. Genes and molecular mechanisms that were found to be critical in simple eukaryotic cells and species have been confirmed in humans mainly by the functional analysis of mammalian orthologues. Here, we review conserved aging mechanisms discovered in different model systems that are implicated in human longevity as well and that could be the target of anti-aging interventions in human.

The role of tumor suppressor p53 in metabolism and energy regulation, and its implication in cancer and lifestyle-related diseases

The tumor suppressor gene p53 is mutated in approximately more than 50% of human cancers. p53 is also referred to as the "cellular gatekeeper" or "guardian of the genome" because it protects the body from spreading mutated genome induced by various stress. When the cells receives stimuli such as DNA damage, oncogene activation, oxidative stress or undernutrition, p53 gives rise to a number of cellular responses, including cell cycle arrest, apoptosis, cellular senescence and metabolic adaptation. Related to energy metabolisms, it has been reported that p53 reduces glycolysis and enhances mitochondrial respiration. p53 is also involved in the regulation of other cellular metabolism and energy production systems: amino acid metabolism, fatty acid metabolism, nucleic acid metabolism, anti-oxidation, mitochondrial quality control, and autophagy. Moreover, recent studies have shown that p53 gene polymorphisms affect life expectancy and lifestyle-related disease such as type 2 diabetes, suggesting that there is a certain relationship between p53 function and metabolic disorders. In addition, mutant p53 protein does not only lose the tumor suppressor function, but it also gains novel oncogenic function and contributes to tumor development, involving cellular metabolism modification. Therefore, the importance of multifunctionality of p53, particularly with regard to intracellular metabolisms, arouses therapeutic interest and calls attention as the key molecule among cancer, lifestyle-related diseases and life expectancy.

Germline TP53 mutation spectrum in Sudanese premenopausal breast cancer patients: correlations with reproductive factors

PURPOSE

The role of non-genetic factors as modifiers of TP53-related hereditary breast cancer (BC) risk is debated. In this regard, little is known about the impact of germline TP53 mutations on BC in sub-Saharan Africa, where the disease often presents in non-contraceptive multiparous premenopausal women with extended history of breastfeeding. Herein, we report the germline TP53 mutations found in a series of 92 Sudanese premenopausal BC patients characterized for reproductive history.

METHODS

The entire TP53 coding sequence, including intron-exon boundaries and UTRs, was analyzed via DHPLC and direct sequencing, and the association of TP53 genotypes with BC risk and with individual lifetime exposures to reproductive factors was investigated with statistical tools.

RESULTS

The germline TP53 mutation spectrum comprised 20 variants, 15 in the non-coding and 5 in the coding region. The latter included a deleterious missense mutation, c.817C>T (p.Arg273Cys), in a unique patient, and the common and functionally relevant coding polymorphism at amino acid 72 [Pro72Arg (rs1042522)]. The non-coding mutations included c.919+1G>A, a known deleterious splice site mutation, also in a unique patient. Notably, the 2 carriers of deleterious TP53 mutations clustered in the subset of cases with stronger reproductive history relative to childbearing age. When analyzed in comparison to population controls, the codon 72 polymorphism did not reveal associations with BC.

CONCLUSIONS

Our study suggests that the codon 72 Arg>Pro polymorphism is not implicated in premenopausal BC susceptibility, whereas multiparity and breastfeeding might be BC risk factors for carriers of deleterious TP53 mutations.

Impaired ribosome biogenesis: mechanisms and relevance to cancer and aging

The biosynthesis of ribosomes is a complex process that requires the coordinated action of many factors and a huge energy investment from the cell. Ribosomes are essential for protein production, and thus for cellular survival, growth and proliferation. Ribosome biogenesis is initiated in the nucleolus and includes: the synthesis and processing of ribosomal RNAs, assembly of ribosomal proteins, transport to the cytoplasm and association of ribosomal subunits. The disruption of ribosome biogenesis at various steps, with either increased or decreased expression of different ribosomal components, can promote cell cycle arrest, senescence or apoptosis. Additionally, interference with ribosomal biogenesis is often associated with cancer, aging and age-related degenerative diseases. Here, we review current knowledge on impaired ribosome biogenesis, discuss the main factors involved in stress responses under such circumstances and focus on examples with clinical relevance.

Association between Alzheimer's Disease and Cancer Risk in South Korea: an 11-year Nationwide Population-Based Study

Background and Purpose

Previous studies have suggested a decreased cancer risk among patients with Alzheimer's disease (AD). There remains a lack of data on the specific types of cancer and risk factors for developing cancer in AD. We evaluated the association between AD and cancer risk, and we examined specific types of cancer.

Methods

A population-based longitudinal study was conducted using the National Health Insurance Service-Senior cohort for 2002–2013. A total of 4,408 AD patients were included in the study, as were 19,150 matched controls. Potential associations between the risk of cancer and AD were analyzed using Cox proportional hazard regressions.

Results

Cancer developed in 12.3% of the AD group patients and in 18.5% of control group subjects. AD was associated with a reduced risk of cancer (hazard ratio [HR], 0.70; 95% confidence intervals, 0.64–0.78). The risk of head and neck cancers was significantly reduced (HR, 0.49), as were risks for cancers of the digestive tract, including stomach cancer (HR, 0.42), colorectal cancer (HR, 0.61), liver and biliary tract cancers (HR, 0.68), and pancreatic cancer (HR, 0.55). Lung and prostate cancer risks were also significantly lower for the AD group (HR, 0.52 and HR, 0.72, respectively).

Conclusions

Our results showed an inverse association between AD and cancer. Further research involving a large number of patients in a hospital based-study is needed to address the biological associations between cancer development and dementia, including AD.

microRNA diagnostic panel for Alzheimer's disease and epigenetic trade-off between neurodegeneration and cancer

microRNAs (miRNAs) have been extensively studied as potential biomarkers for Alzheimer's disease (AD). Their profiles have been analyzed in blood, cerebrospinal fluid (CSF) and brain tissue. However, due to the high variability between the reported data, stemming from the lack of methodological standardization and the heterogeneity of AD, the most promising miRNA biomarker candidates have not been selected. Our literature review shows that out of 137 miRNAs found to be altered in AD blood, 36 have been replicated in at least one independent study, and out of 166 miRNAs reported as differential in AD CSF, 13 have been repeatedly found. Only 3 miRNAs have been consistently reported as altered in three analyzed specimens: blood, CSF and the brain (hsa-miR-146a, hsa-miR-125b, hsa-miR-135a). Nonetheless, all 36 repeatedly differential miRNAs in AD blood are promising as components of the diagnostic panel. Given their predicted functions, such miRNA panel may report multiple pathways contributing to AD pathology, enabling the design of personalized therapies. In addition, the analysis revealed that the miRNAs dysregulated in AD overlap highly with miRNAs implicated in cancer. However, the directions of the miRNA changes are usually opposite in cancer and AD, indicative of an epigenetic trade-off between the two diseases.

Inverse association for diagnosis of Alzheimer's disease subsequent to both melanoma and non-melanoma skin cancers in a large, urban, single-centre, Midwestern US patient population

BACKGROUND

Although literature demonstrates a decreased risk of Alzheimer's disease (AD) in individuals with various cancers, including squamous cell cancers (SCC) and basal cell cancers (BCC) comprising non-melanoma skin cancers (NMSC), there is a paucity of literature to substantiate an association between malignant melanoma (MM) and AD.

OBJECTIVE

The aim of this study was to determine whether an association exists between MM and AD as well as for NMSC and AD.

METHODS

A large urban, Midwestern, US, single-centre, medical record (EMR) data repository was searched between January 2001 and December 2015, to identify all patients at age ≥60 and <89 years with a clinic follow-up of at least 1 year and no diagnosis for AD, MM or NMSC at the time of the study entry. Data collected included age, gender, race and duration of follow-up. MM and NMSC were detected by ICD-9 codes and ICD-10 codes. Incident diagnosis of AD was also detected by ICD-9 and ICD-10 codes. Logistic regression analysis was utilized to obtain crude and adjusted odds ratios (ORs).

RESULTS

Data for a total of 82 925 patients with known race and gender and were detected. After adjusting for confounding factors (race, gender, age, cerebrovascular disease, peripheral vascular disease and diabetes), there was a significant decreased risk of subsequent AD in patients with MM (OR: 0.39; 95% CI: 0.16-0.96; P = 0.042) as well as in patients with BCC (OR: 0.18; 95% CI: 0.08-0.45; P < 0.0001) and for patients with SCC (OR: 0.08; 95% CI: 0.01-0.56; P = 0.013).

CONCLUSION

These findings add to the growing body of evidence for a decreased risk of AD in patients with various cancers and highlight the need for ongoing research to elucidate both neurologic and biologic mechanisms that may underlie this apparent inverse association.

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.

Associations Between TP53 and MDM2 Polymorphisms and the Follicle-Stimulating Hormone/Luteinizing Hormone Ratio in Infertile Women

AIMS

This is a follow-up study based on the results of our previous article, to further explore the effect of the TP53 codon 72 (rs1042522) and MDM2 SNP309 (rs2279744) polymorphisms on basal follicle-stimulating hormone (FSH)/luteinizing hormone (LH) ratios in infertility women.

MATERIALS AND METHODS

The distribution of two genetic polymorphisms (rs1042522 and rs2279744) and basal FSH/LH ratios were tested and analyzed in 1051 in vitro fertilization (IVF) patients at a university-affiliated hospital.

RESULTS

The TP53 codon 72 polymorphism had a significant association with the FSH/LH ratio (group I: FSH/LH <2.3 and group II: FSH/LH ≥2.3) (C/C vs. G/G: odds ratio [OR] = 1.69, 95% confidence interval [CI]: 1.07-2.65, p = 0.02; G/C vs. G/G: OR = 1.86, 95% CI: 1.25-2.77, p = 0.002). In a stratification analysis, C allele carriers and the C/C genotype showed a strong association with positive clinical pregnancy outcomes after IVF compared with G allele carriers and the G/G genotype in the recessive, dominant, and allelic genetic models in group I (C/C vs. G/G: OR = 1.84, 95% CI: 1.25-2.69, p = 0.01; C/C vs. G carrier: OR = 1.52, 95% CI: 1.12-2.07, p = 0.01; C carrier vs. G/G: OR = 1.46, 95% CI: 1.07-2.01, p = 0.02; C allele vs. G allele: OR = 1.34, 95% CI: 1.11-1.62, p = 0.003), no significant associations by stratification were observed for group II. No associations were found between MDM2 SNP309 and either of two groups.

CONCLUSION

The TP53 codon 72 polymorphism is associated with FSH/LH ratios, suggesting that it is a potential predictive genetic marker of IVF outcome in patients younger than 35 years of age with baseline FSH levels below 10 IU/L and who have an FSH/LH ratio <2.3.

Nucleolar Function in Lifespan Regulation

The nucleolus is a prominent membraneless organelle residing within the nucleus. The nucleolus has been regarded as a housekeeping structure mainly known for its role in ribosomal RNA (rRNA) production and ribosome assembly. However, accumulating evidence has revealed its functions in numerous cellular processes that control organismal physiology, thereby taking the nucleolus much beyond its conventional role in ribosome biogenesis. Perturbations in nucleolar functions have been associated with severe diseases such as cancer and progeria. Recent studies have also uncovered the role of the nucleolus in development and aging. In this review we discuss major nucleolar functions that impact organismal aging.

A polymorphism in the tumor suppressor p53 affects aging and longevity in mouse models

Tumor suppressor p53 prevents early death due to cancer development. However, the role of p53 in aging process and longevity has not been well-established. In humans, single nucleotide polymorphism (SNP) with either arginine (R72) or proline (P72) at codon 72 influences p53 activity; the P72 allele has a weaker p53 activity and function in tumor suppression. Here, employing a mouse model with knock-in of human TP53 gene carrying codon 72 SNP, we found that despite increased cancer risk, P72 mice that escape tumor development display a longer lifespan than R72 mice. Further, P72 mice have a delayed development of aging-associated phenotypes compared with R72 mice. Mechanistically, P72 mice can better retain the self-renewal function of stem/progenitor cells compared with R72 mice during aging. This study provides direct genetic evidence demonstrating that p53 codon 72 SNP directly impacts aging and longevity, which supports a role of p53 in regulation of longevity.

How long most animals live depends on the balance between the biological processes that allow them to regenerate their tissues when damaged and those that prevent them from developing cancer. Regeneration relies mostly on cells, in particular stem cells, dividing to make new cells, while cancer occurs when cell division becomes uncontrolled.

Tumor suppressor genes protect against cancer. One such gene encodes a protein called p53 that eliminates damaged cells before they can become cancerous. The p53 protein is also believed to be involved in regulating how quickly an animal ages and how long it lives, but this second role has not yet been clearly established.

Previous studies using different strategies to change the activity of p53 in several mouse models have led to inconsistent results. However, the mouse models used in these earlier studies did not reflect how p53 works under normal conditions.

Zhao et al. have now used mice in which the mouse gene for p53 was replaced with one of two versions of the equivalent human gene to study its impact on lifespan and the aging process. The two versions of p53 only differ slightly; a single building block of the protein, the amino acid at position 72, is a proline in one version but an arginine in the other. This difference makes one version of p53 weaker than the other; in other words, it is less able to eliminate damaged cells. Zhao et al. revealed that the mice with the weaker p53 lived for longer and appeared to age more slowly too. Further experiments showed that the stem cells in the mice with a weaker p53 were able to keep dividing and create new cells for longer. This is important because a decline in this activity – which is known as self-renewal – is a hallmark of aging.

Together these findings show that a small yet common change in p53 impacts both aging and lifespan, possibly by altering how stem cells are regulated. Further work is now needed to better understand why the different versions of p53 have different effects on stem cells.

Do Cancer Drugs Counteract Neurodegeneration? Repurposing for Alzheimer's Disease

In spite of in depth investigations in the field of the amyloid cascade hypothesis, so far, no disease modifying therapy has been developed for Alzheimer's disease (AD). The pathophysiology provides some evidence of the inverse correlation between cancer and AD. Both AD and cancer are characterized by abnormal cellular behaviors; trigger factors along with a meta synchronously action is expected to drive cancer or neurodegeneration, supporting, respectively, progressive neuronal loss or uncontrolled cell proliferation in cancer cells. So far, cancer and AD are seemingly two opposite ends of the same biological spectrum. Basic science increasingly indicates shared molecular mechanisms between cancer and AD and gives weight to key relevant biological theories; according to them, the inverse tuning of clustered gene expression, the sharing of mutual independent pathway or the deregulated unfolded proteins system (UPR) may count for this inverse association. Additionally, the common biological background gave credibility to the recent discovery of a repurposing role for cancer drugs in AD. It refers to the development of new uses for existing pharmaceuticals having the same role as the original mechanism or to the discovery of a new drug action with disease modifying effects. The present review summarizes the most important biological theories that link neurodegeneration and cancer and provides an up-to-date revision of the repurposing cancer agents for AD. The review also addresses the gap of knowledge, since drug cancer repositioning holds an important promise but further investigations are warranted to ascertain the clinical relevance of such attractive clinical candidate compounds for AD.

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

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

DNA damage responses and p53 in the aging process

The genome is constantly attacked by genotoxic insults. DNA damage has long been established as a cause of cancer development through its mutagenic consequences. Conversely, radiation therapy and chemotherapy induce DNA damage to drive cells into apoptosis or senescence as outcomes of the DNA damage response (DDR). More recently, DNA damage has been recognized as a causal factor for the aging process. The role of DNA damage in aging and age-related diseases is illustrated by numerous congenital progeroid syndromes that are caused by mutations in genome maintenance pathways. During the past 2 decades, understanding how DDR drives cancer development and contributes to the aging process has progressed rapidly. It turns out that the DDR factor p53 takes center stage during tumor development and also plays an important role in the aging process. Studies in metazoan models ranging from Caenorhabditis elegans to mammals have revealed cell-autonomous and systemic DDR mechanisms that orchestrate adaptive responses that augment maintenance of the aging organism amid gradually accumulating DNA damage.

Identification of polymorphisms in cancer patients that differentially affect survival with age

The World Health Organization predicts that the proportion of the world's population over 60 will almost double from 12% to 22% between 2015 and 2050. Ageing is the biggest risk factor for cancer, which is a leading cause of deaths worldwide. Unfortunately, research describing how genetic variants affect cancer progression commonly neglects to account for the ageing process. Herein is the first systematic analysis that combines a large longitudinal data set with a targeted candidate gene approach to examine the effect of genetic variation on survival as a function of age in cancer patients. Survival was significantly decreased in individuals with heterozygote or rare homozygote (i.e. variant) genotypes compared to those with a common homozygote genotype (i.e. wild type) for two single nucleotide polymorphisms (rs11574358 and rs4147918), one gene (SIRT3) and one pathway (FoxO signalling) in an age-dependent manner. All identified genes and pathways have previously been associated with ageing and cancer. These observations demonstrate that there are ageing-related genetic elements that differentially affect mortality in cancer patients in an age-dependent manner. Understanding the genetic determinants affecting prognosis differently with age will be invaluable to develop age-specific prognostic biomarkers and personalized therapies that may improve clinical outcomes for older individuals.

The emerging role of alternative splicing in senescence and aging

Deregulation of precursor mRNA splicing is associated with many illnesses and has been linked to age-related chronic diseases. Here we review recent progress documenting how defects in the machinery that performs intron removal and controls splice site selection contribute to cellular senescence and organismal aging. We discuss the functional association linking p53, IGF-1, SIRT1, and ING-1 splice variants with senescence and aging, and review a selection of splicing defects occurring in accelerated aging (progeria), vascular aging, and Alzheimer's disease. Overall, it is becoming increasingly clear that changes in the activity of splicing factors and in the production of key splice variants can impact cellular senescence and the aging phenotype.

Dysfunction of the MDM2/p53 axis is linked to premature aging

The tumor suppressor p53, a master regulator of the cellular response to stress, is tightly regulated by the E3 ubiquitin ligase MDM2 via an autoregulatory feedback loop. In addition to its well-established role in tumorigenesis, p53 has also been associated with aging in mice. Several mouse models with aberrantly increased p53 activity display signs of premature aging. However, the relationship between dysfunction of the MDM2/p53 axis and human aging remains elusive. Here, we have identified an antiterminating homozygous germline mutation in MDM2 in a patient affected by a segmental progeroid syndrome. We show that this mutation abrogates MDM2 activity, thereby resulting in enhanced levels and stability of p53. Analysis of the patient's primary cells, genome-edited cells, and in vitro and in vivo analyses confirmed the MDM2 mutation's aberrant regulation of p53 activity. Functional data from a zebrafish model further demonstrated that mutant Mdm2 was unable to rescue a p53-induced apoptotic phenotype. Altogether, our findings indicate that mutant MDM2 is a likely driver of the observed segmental form of progeria.

Investigating the genetic relationship between Alzheimer's disease and cancer using GWAS summary statistics

Growing evidence from both epidemiology and basic science suggest an inverse association between Alzheimer's disease (AD) and cancer. We examined the genetic relationship between AD and various cancer types using GWAS summary statistics from the IGAP and GAME-ON consortia. Sample size ranged from 9931 to 54,162; SNPs were imputed to the 1000 Genomes European panel. Our results based on cross-trait LD Score regression showed a significant positive genetic correlation between AD and five cancers combined (colon, breast, prostate, ovarian, lung; r _g = 0.17, P = 0.04), and specifically with breast cancer (ER-negative and overall; r _g = 0.21 and 0.18, P = 0.035 and 0.034) and lung cancer (adenocarcinoma, squamous cell carcinoma and overall; r _g = 0.31, 0.38 and 0.30, P = 0.029, 0.016, and 0.006). Estimating the genetic correlation in specific functional categories revealed mixed positive and negative signals, notably stronger at annotations associated with increased enhancer activity. This suggests a role of gene expression regulators in the shared genetic etiology between AD and cancer, and that some shared variants modulate disease risk concordantly while others have effects in opposite directions. Due to power issues, we did not detect cross-phenotype associations at individual SNPs. This genetic overlap is not likely driven by a handful of major loci. Our study is the first to examine the co-heritability of AD and cancer leveraging large-scale GWAS results. The functional categories highlighted in this study need further investigation to illustrate the details of the genetic sharing and to bridge between different levels of associations.

Increased Arf/p53 activity in stem cells, aging and cancer

Arf/p53 pathway protects the cells against DNA damage induced by acute stress. This characteristic is the responsible for its tumor suppressor activity. Moreover, it regulates the chronic type of stress associated with aging. This is the basis of its anti‐aging activity. Indeed, increased gene dosage of Arf/p53 displays elongated longevity and delayed aging. At a cellular level, it has been recently shown that increased dosage of Arf/p53 delays age‐associated stem cell exhaustion and the subsequent decline in tissue homeostasis and regeneration. However, p53 can also promote aging if constitutively activated. In this context, p53 reduces tissue regeneration, which correlates with premature exhaustion of stem cells. We discuss here the current evidence linking the Arf/p53 pathway to the processes of aging and cancer through stem cell regulation.

TP53 Arg72Pro, mortality after cancer, and all-cause mortality in 105,200 individuals

Rs1042522 (Arg72Pro) is a functional polymorphism of TP53. Pro72 has been associated with lower all-cause mortality and lower mortality after cancer. We hypothesized that TP53 Pro72 is associated with lower mortality after cancer, lower all-cause mortality, and with increased cancer incidence in the general population in a contemporary cohort. We genotyped 105,200 individuals aged 20–100 years from the Copenhagen General Population Study, recruited in 2003–2013, and followed them in Danish health registries. During follow-up 5,531 individuals died and 5,849 developed cancer. Hazard ratios for mortality after cancer were 1.03 (95% confidence interval:0.93–1.15) for Arg/Pro and 0.96 (95% CI:0.79–1.18) for Pro/Pro versus Arg/Arg. Hazard ratios for all-cause mortality were 0.99 (95% CI:0.93–1.04) for Arg/Pro and 1.09 (95% CI:0.98–1.21) for Pro/Pro versus Arg/Arg. Risk of cancer specific mortality, cardiovascular mortality, and respiratory mortality were not associated with Arg72Pro genotype overall; however, in exploratory subgroup analyses, genotype-associated risks of malignant melanoma and diabetes were altered. Considering multiple comparisons the latter findings may represent play of chance. The TP53 Arg72Pro genotype was not associated with mortality after cancer, all-cause mortality, or cancer incidence in the general population in a contemporary cohort. Our main conclusion is therefore a lack of reproducing an effect of TP53 Arg72Pro genotype on mortality.

Uncoupling associations of risk alleles with endophenotypes and phenotypes: insights from the ApoB locus and heart-related traits

Traditionally, genomewide association studies (GWAS) have emphasized the benefits of large samples in the analyses of age‐related traits rather than their specific properties. We adopted a realistic concept of genetic susceptibility to inherently heterogeneous, age‐related traits driven by the elusive role of evolution in their properties. We analyzed in detail the associations of rs693 and rs562338 polymorphisms representing the Apolipoprotein B locus with endophenotypes (total cholesterol [TC] and high‐density lipoprotein cholesterol) and phenotypes (myocardial infarction [MI] and survival) in four large‐scale studies, which include 20 748 individuals with 2357 MI events. We showed that a strong, robust predisposition of rs693 and rs562338 to TC (β = 0.72, P = 7.7 × 10⁻³⁰ for rs693 and β = −1.08, P = 9.8 × 10⁻⁴² for rs562338) is not translated into a predisposition to MI and survival. The rs693_A allele influences risks of MI and mortality after MI additively with lipids. This allele shows antagonistic effects—protecting against MI risks (β = −0.18, P = 1.1 × 10⁻⁵) or increasing MI risks (β = 0.15, P = 2.8 × 10⁻³) and mortality after MI, in different populations. Paradoxically, increased TC concentrations can be protective against MI for the rs693_A allele carriers. Our results uncouple the influences of the same alleles on endophenotypes and phenotypes despite potential causal relationships among the latter. Our strategy reveals virtually genomewide significance for the associations of rs693 with MI (P = 5.5 × 10⁻⁸) that is contrasted with a weak estimate following the traditional, sample‐size‐centered GWAS strategy (P = 0.16) in the same sample. These results caution against the use of the traditional GWAS strategy for gaining profound insights into genetic predisposition to healthspan and lifespan.

Do p53 stress responses impact organismal aging?

p53 is a transcriptional regulator that responds to cellular stresses to suppress oncogenesis, but some of these responses can have unintended consequences that influence non-cancer-related aging processes. The impact of these consequences is not well understood-partly due to the many complex processes that influence p53 function and partly due to the vast array of processes that p53 affects. p53 has the potential to both accelerate and hinder cellular aging processes, which would likely have antithetical biological outcomes with regard to organismal aging. To accelerate aging, p53 induces apoptosis or cell cycle arrest as a prerequisite to cellular senescence; both can impair the mobilization of stem and progenitor cell populations. To suppress aging, p53 inhibits unregulated proliferation pathways that could lead to cellular senescence and a senescence-associated secretory phenotype (SASP), which creates a pro-inflammatory and degenerative tissue milieu. A review of mouse models supports both possibilities, highlighting the complexity of the p53 influence over organismal aging. A deeper knowledge of how p53 integrates and is integrated with various biological processes will improve our understanding of its influence over the aging process.

An overview on the role of dietary phenolics for the treatment of cancers

Plant derived phenolic compounds have been shown to inhibit the initiation and progression of cancers by modulating genes regulating key processes such as: (a) oncogenic transformation of normal cells; (b) growth and development of tumors; and (c) angiogenesis and metastasis. Recent studies focusing on identifying the molecular basis of plant phenolics-induced cancer cell death have demonstrated down-regulation of: (a) oncogenic survival kinases such as PI3K and Akt; (b) cell proliferation regulators that include Erk1/2, D-type Cyclins, and Cyclin Dependent Kinases (CDKs); (c) transcription factors such as NF-kβ, NRF2 and STATs; (d) histone deacetylases HDAC1 and HDAC2; and (e) angiogenic factors VEGF, FGFR1 and MIC-1. Furthermore, while inhibiting oncogenic proteins, the phenolic compounds elevate the expression of tumor suppressor proteins p53, PTEN, p21, and p27. In addition, plant phenolic compounds and the herbal extracts rich in phenolic compounds modulate the levels of reactive oxygen species (ROS) in cells thereby regulate cell proliferation, survival and apoptosis. Furthermore, recent studies have demonstrated that phenolic compounds undergo transformation in gut microbiota thereby acquire additional properties that promote their biological activities. In vitro observations, preclinical and epidemiological studies have shown the involvement of plant phenolic acids in retarding the cancer growth. However, to date, there is no clinical trial as such testing the role of plant phenolic compounds for inhibiting tumor growth in humans. More over, several variations in response to phenolic acid rich diets-mediated treatment among individuals have also been reported, raising concerns about whether phenolic acids could be used for treating cancers. Therefore, we have made an attempt to (a) address the key structural features of phenolic acids required for exhibiting potent anti-cancer activity; (b) review the reported findings about the mechanisms of action of phenolic compounds and their transformation by gut microbiota; and (c) update the toxicological aspects and anti-tumor properties of phenolic compounds and extracts containing phenolic compounds in animals.

An Extensive Empirical Comparison of Probabilistic Hierarchical Classifiers in Datasets of Ageing-Related Genes

This study comprehensively evaluates the performance of five types of probabilistic hierarchical classification methods used for predicting Gene Ontology (GO) terms related to ageing. Of those tested, a new hybrid of a Local Hierarchical Classifier (LHC) and the Predictive Clustering Tree algorithm (LHC-PCT) had the best predictive accuracy results. We also tested the impact of two types of variations in most hierarchical classification algorithms, namely: (a) changing the base algorithm (we tested Naive Bayes and Support Vector Machines), and the impact of (b) using or not the Correlation based Feature Selection (CFS) algorithm in a pre-processing step. In total, we evaluated the predictive performance of 17 variations of hierarchical classifiers across 15 datasets of ageing and longevity-related genes. We conclude that the LHC-PCT algorithm ranks better across several tests (seven out of 12). In addition, we interpreted the models generated by the PCT algorithm to show how hierarchical classification algorithms can be used to extract biological insights out of the ageing-related datasets that we compiled.

TP53 and MDM2 single nucleotide polymorphisms influence survival in non-del(5q) myelodysplastic syndromes

P53 is a key regulator of many cellular processes and is negatively regulated by the human homolog of murine double minute-2 (MDM2) E3 ubiquitin ligase. Single nucleotide polymorphisms (SNPs) of either gene alone, and in combination, are linked to cancer susceptibility, disease progression, and therapy response. We analyzed the interaction of TP53 R72P and MDM2 SNP309 SNPs in relationship to outcome in patients with myelodysplastic syndromes (MDS). Sanger sequencing was performed on DNA isolated from 208 MDS cases. Utilizing a novel functional SNP scoring system ranging from +2 to −2 based on predicted p53 activity, we found statistically significant differences in overall survival (OS) (p = 0.02) and progression-free survival (PFS) (p = 0.02) in non-del(5q) MDS patients with low functional scores. In univariate analysis, only IPSS and the functional SNP score predicted OS and PFS in non-del(5q) patients. In multivariate analysis, the functional SNP score was independent of IPSS for OS and PFS. These data underscore the importance of TP53 R72P and MDM2 SNP309 SNPs in MDS, and provide a novel scoring system independent of IPSS that is predictive for disease outcome.

Gene expression signatures of human cell and tissue longevity

Different cell types within the body exhibit substantial variation in the average time they live, ranging from days to the lifetime of the organism. The underlying mechanisms governing the diverse lifespan of different cell types are not well understood. To examine gene expression strategies that support the lifespan of different cell types within the human body, we obtained publicly available RNA-seq data sets and interrogated transcriptomes of 21 somatic cell types and tissues with reported cellular turnover, a bona fide estimate of lifespan, ranging from 2 days (monocytes) to a lifetime (neurons). Exceptionally long-lived neurons presented a gene expression profile of reduced protein metabolism, consistent with neuronal survival and similar to expression patterns induced by longevity interventions such as dietary restriction. Across different cell lineages, we identified a gene expression signature of human cell and tissue turnover. In particular, turnover showed a negative correlation with the energetically costly cell cycle and factors supporting genome stability, concomitant risk factors for aging-associated pathologies. In addition, the expression of p53 was negatively correlated with cellular turnover, suggesting that low p53 activity supports the longevity of post-mitotic cells with inherently low risk of developing cancer. Our results demonstrate the utility of comparative approaches in unveiling gene expression differences among cell lineages with diverse cell turnover within the same organism, providing insights into mechanisms that could regulate cell longevity.

Inverse relationship between cancer and Alzheimer's disease: a systemic review meta-analysis

Alzheimer's disease (AD) and cancer are both prevalent in the elderly. Some epidemiological researches have reported the negative association between AD and cancer, but the results are controversial. The present meta-analysis is aimed to clarify the association between cancer and AD. PubMed, Web of knowledge and the Cochrane library databases were searched for eligible publications. The analysis indicated that history of cancer was associated with a reduced risk of AD (ES 0.62, 95 % CIs 0.53-0.74; p < 0.001), with no significance between-study heterogeneity and publication bias. Similar results were found in subgroup analysis by stratifying variables with education and APOEε4 carriers, years of follow-up and sample size of cases. The negative association was also found in analysis of risk of cancer among patients with AD (ES 0.59, 95 % CIs 0.42-0.82; p = 0.002), but with evidence of between-study heterogeneity and publication bias. In order to identify sources of the heterogeneity, subgroup analysis was performed by stratifying variable with or without education adjusted, sample size of cases and years of follow-up. Negative association was found in all subgroup analysis except in studies with less than 5-year follow-up and with heterogeneity disappeared only in the subgroup analysis stratified with sample size of cases. Our results in the present meta-analysis support the negative association between AD and cancer. But further well-designed perspective studies with strict control of confounding factors are needed to clarify the association between AD and cancer.

Diametrical diseases reflect evolutionary-genetic tradeoffs: Evidence from psychiatry, neurology, rheumatology, oncology and immunology

Tradeoffs centrally mediate the expression of human adaptations. We propose that tradeoffs also influence the prevalence and forms of human maladaptation manifest in disease. By this logic, increased risk for one set of diseases commonly engenders decreased risk for another, diametric, set of diseases. We describe evidence for such diametric sets of diseases from epidemiological, genetic and molecular studies in four clinical domains: (i) psychiatry (autism vs psychotic-affective conditions), (ii) rheumatology (osteoarthritis vs osteoporosis), (iii) oncology and neurology (cancer vs neurodegenerative disorders) and (iv) immunology (autoimmunity vs infectious disease). Diametric disorders are important to recognize because genotypes or environmental factors that increase risk for one set of disorders protect from opposite disorders, thereby providing novel and direct insights into disease causes, prevention and therapy. Ascertaining the mechanisms that underlie disease-related tradeoffs should also indicate means of circumventing or alleviating them, and thus reducing the incidence and impacts of human disease in a more general way.

Puzzling role of genetic risk factors in human longevity: "risk alleles" as pro-longevity variants

Complex diseases are major contributors to human mortality in old age. Paradoxically, many genetic variants that have been associated with increased risks of such diseases are found in genomes of long-lived people, and do not seem to compromise longevity. Here we argue that trade-off-like and conditional effects of genes can play central role in this phenomenon and in determining longevity. Such effects may occur as result of: (i) antagonistic influence of gene on the development of different health disorders; (ii) change in the effect of gene on vulnerability to death with age (especially, from “bad” to “good”); (iii) gene–gene interaction; and (iv) gene–environment interaction, among other factors. A review of current knowledge provides many examples of genetic factors that may increase the risk of one disease but reduce chances of developing another serious health condition, or improve survival from it. Factors that may increase risk of a major disease but attenuate manifestation of physical senescence are also discussed. Overall, available evidence suggests that the influence of a genetic variant on longevity may be negative, neutral or positive, depending on a delicate balance of the detrimental and beneficial effects of such variant on multiple health and aging related traits. This balance may change with age, internal and external environments, and depend on genetic surrounding. We conclude that trade-off-like and conditional genetic effects are very common and may result in situations when a disease “risk allele” can also be a pro-longevity variant, depending on context. We emphasize importance of considering such effects in both aging research and disease prevention.

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.

Role of tumor suppressor genes in the cancer-associated reprogramming of human induced pluripotent stem cells

Because of their pluripotent characteristics, human induced pluripotent stem cells (iPSCs) possess great potential for therapeutic application and for the study of degenerative disorders. These cells are generated from normal somatic cells, multipotent stem cells, or cancer cells. They express embryonic stem cell markers, such as OCT4, SOX2, NANOG, SSEA-3, SSEA-4, and REX1, and can differentiate into all adult tissue types, both in vitro and in vivo. However, some of the pluripotency-promoting factors have been implicated in tumorigenesis. Here, we describe the merits of tumor suppresser genes as reprogramming factors for the generation of iPSCs without tumorigenic activity. The initial step of reprogramming is induction of the exogenous pluripotent factors to generate the oxidative stress that leads to senescence by DNA damage and metabolic stresses, thus inducing the expression of tumor suppressor genes such as p21^CIP1 and p16^INK4a through the activation of p53 to be the pre-induced pluripotent stem cells (pre-iPSCs). The later stage includes overcoming the barrier of reprogramming-induced senescence or cell-cycle arrest by shutting off the function of these tumor suppressor genes, followed by the induction of endogenous stemness genes for the full commitment of iPSCs (full-iPSCs). Thus, the reactive oxygen species (ROS) produced by oxidative stress might be critical for the induction of endogenous reprogramming-factor genes via epigenetic changes or antioxidant reactions. We also discuss the critical role of tumor suppressor genes in the evaluation of the tumorigenicity of human cancer cell-derived pluripotent stem cells, and describe how to overcome their tumorigenic properties for application in stem cell therapy in the field of regenerative medicine.