Exogenous Stressors Research Articles

Genomic Instability in Kidney Cancer: Etiologies and Treatment Opportunities

Genomic instability is a hallmark of cancer, allowing for cancer initiation, proliferation, and progression through the accumulation of driver mutations. This instability seen in cancer arises due to a variety of factors in the cancer cell itself as well as in the cell’s environment, including endogenous and exogenous stressors leading to DNA damage in the setting of deficiency in DNA damage response (DDR). While genomic instability is beneficial to cancer cell growth and survival, it also creates targetable vulnerabilities in the cell. Kidney cancer displays low to moderate genomic instability, yet does not have frequent mutations in canonical DDR genes and is not typically responsive to DNA damaging therapies. In this review, the etiology of genomic instability in kidney cancer, with a primary focus on clear cell renal cell carcinoma (ccRCC) histology, is discussed; and, pre-clinical data supporting the use of agents targeting DDR in ccRCC is summarized with associated progress towards clinical applications.

Quality evaluation of indoor‐ and outdoor‐cultured sea cucumber ( Apostichopus japonicus ) seedlings: Insight from survival and immune performance in response to combined stress of hyperthermia and hyposalinity

The mass mortalities of sea cucumber Apostichpous japonicus have prevailed in northern China, mainly attributing to the emergence of extreme environmental conditions, that is hyperthermia and hyposalinity. The high-quality sea cucumber seedlings appear to possess more robust resistance to adverse conditions. There are usually indoor- and outdoor-cultured seedlings in industrial production of sea cucumbers. Although the outdoor-cultured sea cucumbers are practically considered to be more strong and robust, the effective evaluation approach to distinguish these seedlings has been scarce. The current study compared survival and immune performances of indoor- and outdoor-cultured A. japonicus under combined exogenous stressors, that is hyperthermia and hyposalinity. Results based on secondary stress induction revealed that the activities of immune enzymes and levels of catecholamines in body wall of outdoor-cultured seedlings were prominently higher than those of indoor-cultured seedlings recovered for 0–72 hr following sublethal stress (30°C and 25 psu of salinity). The opposite case occurred on immune enzymes in coelomic fluid of the two sources of seedlings except for myeloperoxidase. Importantly, the outdoor-cultured seedlings, which were recovered for 72 hr after sublethal stress, exhibited a 93% of cumulative survival rate following 7 days of recovery after lethal stress (33°C and 20 psu of salinity), 27% higher than the indoor-cultured seedlings. Collectively, the outdoor-cultured A. japonicus seedlings showed more superior quality than the hatchery-produced seedlings in terms of survival and immune performance. These findings provide practically useful information towards quality distinction of the indoor- and outdoor-cultured sea cucumbers, which could benefit the aquaculture industry to obtain high-quality seedlings.

Prion disease is accelerated in mice lacking stress-induced heat shock protein 70 (HSP70)

Prion diseases are a group of incurable neurodegenerative disorders that affect humans and animals via infection with proteinaceous particles called prions. Prions are composed of PrPSc, a misfolded version of the cellular prion protein (PrPC). During disease progression, PrPSc replicates by interacting with PrPC and inducing its conversion to PrPSc As PrPSc accumulates, cellular stress mechanisms are activated to maintain cellular proteostasis, including increased protein chaperone levels. However, the exact roles of several of these chaperones remain unclear. Here, using various methodologies to monitor prion replication (i.e. protein misfolding cyclic amplification and cellular and animal infectivity bioassays), we studied the potential role of the molecular chaperone heat shock protein 70 (HSP70) in prion replication in vitro and in vivo Our results indicated that pharmacological induction of the heat shock response in cells chronically infected with prions significantly decreased PrPSc accumulation. We also found that HSP70 alters prion replication in vitro More importantly, prion infection of mice lacking the genes encoding stress-induced HSP70 exhibited accelerated prion disease progression compared with WT mice. In parallel with HSP70 being known to respond to endogenous and exogenous stressors such as heat, infection, toxicants, and ischemia, our results indicate that HSP70 may also play an important role in suppressing or delaying prion disease progression, opening opportunities for therapeutic intervention.

What sustains the multidrug resistance phenotype beyond ABC efflux transporters? Looking beyond the tip of the iceberg.

Identification of multidrug (MDR) efflux transporters that belong to the ATP-Binding Cassette (ABC) superfamily, represented an important breakthrough for understanding cancer multidrug resistance (MDR) and its possible overcoming. However, recent data indicate that drug resistant cells have a complex intracellular physiology that involves constant changes in energetic and oxidative-reductive metabolic pathways, as well as in the molecular circuitries connecting mitochondria, endoplasmic reticulum (ER) and lysosomes. The aim of this review is to discuss the key molecular mechanisms of cellular reprogramming that induce and maintain MDR, beyond the presence of MDR efflux transporters. We specifically highlight how cancer cells characterized by high metabolic plasticity - i.e. cells able to shift the energy metabolism between glycolysis and oxidative phosphorylation, to survive both the normoxic and hypoxic conditions, to modify the cytosolic and mitochondrial oxidative-reductive metabolism, are more prone to adapt to exogenous stressors such as anti-cancer drugs and acquire a MDR phenotype. Similarly, we discuss how changes in mitochondria dynamics and mitophagy rates, changes in proteome stability ensuring non-oncogenic proteostatic mechanisms, changes in ubiquitin/proteasome- and autophagy/lysosome-related pathways, promote the cellular survival under stress conditions, along with the acquisition or maintenance of MDR. After dissecting the complex intracellular crosstalk that takes place during the development of MDR, we suggest that mapping the specific adaptation pathways underlying cell survival in response to stress and targeting these pathways with potent pharmacologic agents may be a new approach to enhance therapeutic efficacy against MDR tumors.

Sub-Chronic Microcystin-LR Liver Toxicity in Preexisting Diet-Induced Nonalcoholic Steatohepatitis in Rats.

Microcystin-LR (MCLR) is a hepatotoxic cyanotoxin reported to cause a phenotype similar to nonalcoholic steatohepatitis (NASH). NASH is a common progressive liver disease that advances in severity due to exogenous stressors such as poor diet and toxicant exposure. Our objective was to determine how sub-chronic MCLR toxicity affects preexisting diet-induced NASH. Sprague-Dawley rats were fed one of three diets for 10 weeks: control, methionine and choline deficient (MCD), or high fat/high cholesterol (HFHC). After six weeks of diet, animals received vehicle, 10 µg/kg, or 30 µg/kg MCLR via intraperitoneal injection every other day for the final 4 weeks. Incidence and severity scoring of histopathology endpoints suggested that MCLR toxicity drove NASH to a less fatty and more fibrotic state. In general, expression of genes involved in de novo lipogenesis and fatty acid esterification were altered in favor of decreased steatosis. The higher MCLR dose increased expression of genes involved in fibrosis and inflammation in the control and HFHC groups. These data suggest MCLR toxicity in the context of preexisting NASH may drive the liver to a more severe phenotype that resembles burnt-out NASH.

Sex ratios at birth vary with environmental harshness but not maternal condition

The sex ratio at birth (SRB) may be patterned by maternal condition and/or environmental stressors. However, despite decades of research, empirical results from across the social and biological sciences are equivocal on this topic. Using longitudinal individual-level data from a US population during the interwar period (1918–1939), inclusive of three distinct eras (Spanish Flu, Roaring ‘20 s, and the Great Depression), we evaluate predictions from two theoretical frameworks used to study patterning in SRB – (1) ‘frail males’ and (2) adaptive sex-biased investment theory (Trivers-Willard). The first approach centers on greater male susceptibility to exogenous stressors and argues that offspring survival should be expected to differ between ‘good’ and ‘bad’ times. The second approach contends that mothers themselves play a direct role in manipulating offspring SRB, and that those in better condition should invest more in sons. In-line with ‘frail male’ predictions, we find that boys are less likely to be born during the environmentally challenging times of the Spanish Flu and Great Depression. However, we find no evidence that maternal condition is associated with sex ratios at birth, a result inconsistent with the Trivers-Willard hypothesis.

Frailty and Intrinsic Capacity: Two Distinct but Related Constructs.

Frailty is a clinical condition characterized by the individual's increased vulnerability to endogenous and exogenous stressors. It is determined by the reduction of homeostatic capacities of the organism and responsible for a marked risk of adverse health outcomes (including functional loss and mortality). Frailty originates from the geriatric background and may pave the way toward a model of care centered on the person, deviating from the traditional and obsolete disease-focused approach. Unfortunately, many controversies have affected the field of frailty over the years and ambiguities have been growing. In particular, the common use of frailty as condition to “exclude” from interventions is a worrisome trend. In fact, the detection of frailty should instead represent the entry point for a more in-depth analysis with the aim of identifying the causes of individual's increased vulnerability and implementing a person-tailored intervention plan. With the aim of promoting a more comprehensive and appropriate assessment of the aging population, the World Health Organization introduced the concept of intrinsic capacity (IC), defined as the composite of all physical and mental capacities that an individual can draw upon during his/her life. Frailty and IC are two constructs stemming from the same need of overcoming traditional medical paradigms that negatively impact on the correct way clinical and research practice should be conducted in older persons. In this article, we describe the similarities and differences between the two constructs, highlighting how geriatric medicine contributed to their development and will be crucial for their further integration in future healthcare models.

Epigenome-wide skeletal muscle DNA methylation profiles at the background of distinct metabolic types and ryanodine receptor variation in pigs

BackgroundEpigenetic variation may result from selection for complex traits related to metabolic processes or appear in the course of adaptation to mediate responses to exogenous stressors. Moreover epigenetic marks, in particular the DNA methylation state, of specific loci are driven by genetic variation. In this sense, polymorphism with major gene effects on metabolic and cell signaling processes, like the variation of the ryanodine receptors in skeletal muscle, may affect DNA methylation.MethodsDNA-Methylation profiles were generated applying Reduced Representation Bisulfite Sequencing (RRBS) on 17 Musculus longissimus dorsi samples. We examined DNA methylation in skeletal muscle of pig breeds differing in metabolic type, Duroc and Pietrain. We also included F2 crosses of these breeds to get a first clue to DNA methylation sites that may contribute to breed differences. Moreover, we compared DNA methylation in muscle tissue of Pietrain pigs differing in genotypes at the gene encoding the Ca2+ release channel (RYR1) that largely affects muscle physiology.ResultsMore than 2000 differently methylated sites were found between breeds including changes in methylation profiles of METRNL, IDH3B, COMMD6, and SLC22A18, genes involved in lipid metabolism. Depending on RYR1 genotype there were 1060 differently methylated sites including some functionally related genes, such as CABP2 and EHD, which play a role in buffering free cytosolic Ca2+ or interact with the Na+/Ca2+ exchanger.ConclusionsThe change in the level of methylation between the breeds is probably the result of the long-term selection process for quantitative traits involving an infinite number of genes, or it may be the result of a major gene mutation that plays an important role in muscle metabolism and triggers extensive compensatory processes.

What can we learn from the hair of the dog? Complex effects of endogenous and exogenous stressors on canine hair cortisol.

Hair is an emerging biological matrix in which to measure chronic HPA axis activity, offering a longer term view into an animal’s life. We explored effects of exogenous (e.g. lifestyle, medications, social environment) and endogenous (e.g. disease, behaviour) stressors on hair cortisol concentration (HCC) in a population of Border Collies (BCs). Owners of BCs were recruited and reported their dog’s lifestyle, clinical history, anxiety-related behaviour, and collected a white hair sample from their dog’s dorsal neck region. HCC was determined using established methods with a commercial cortisol assay kit. Samples from 135 BCs were analysed, with 91 healthy controls and 44 diagnosed with epilepsy as a model disease. Factors associated with higher HCC included psychosocial stressors (living with three or more other dogs) and lifestyle (engaging in competitive flyball); while factors associated with lower HCC included anxiety (stranger-directed and non-social), health (epilepsy diagnosis, with number of seizures to date negatively correlated with HCC) and medication (certain anti-epileptic drugs were associated with elevated or reduced HCC). These novel results highlight the potential of chronic stress with frequent or persisting HPA-axis hyperactivity leading to a state of hypocortisolism, and the need to consider stressor recency and recurrence when interpreting HCC data.

Evolution of Resistance in Cancer: A Cell Cycle Perspective.

Resistance of neoplastic cells to therapy is considered a key challenge in the treatment of cancer. Emergence of resistance is commonly attributed to the gradual mutational evolution of neoplastic cells. However, accumulating evidence suggests that exogenous stressors could significantly accelerate the emergence of resistant clones during the course of treatment. Herein, we review molecular mechanisms that regulate the evolution of resistance in a tumor with particular emphasis on the role of cell cycle.

Sub-lethal concentrations of neonicotinoid insecticides at the field level affect negatively honey yield: Evidence from a 6-year survey of Greek apiaries.

The threats posed by neonicotinoid insecticides to bee populations have been the focus of considerable research. Previous work has shed new light on the effects of neonicotinoids on bees by uncovering pathways through which neonicotinoids affect bee population dynamics and the potential interactions they have with exogenous stressors. Yet, little is known about whether these effects translate in a field-relevant setting to substantial losses in honey yields for commercial beekeepers. Here, we used data from a 6-year survey of 60 apiaries in Greece and economic modelling to assess at the field level the effects of neonicotinoid insecticides on honey production. Based on production function estimates, we found that sub-lethal concentrations of two widely used neonicotinoid insecticides (imidacloprid and thiamethoxam) detected in the nectar of flowers resulted in substantial losses in honey production for commercial beekeepers in our sample. By simulating a scenario with ideal pathogenic and environmental conditions, we found that the magnitude of the neonicotinoid effects decreases significantly under ideal conditions providing evidence for possible synergies at the field between neonicotinoids and environmental and pathogenic factors. Moreover, in a replicated study with grouped apiaries, we found evidence that the marginal effects of neonicotinoids on honey production vary across apiaries facing different conditions.

Potential Applications of NRF2 Inhibitors in Cancer Therapy

The NRF2/KEAP1 pathway represents one of the most important cell defense mechanisms against exogenous or endogenous stressors. Indeed, by increasing the expression of several cytoprotective genes, the transcription factor NRF2 can shelter cells and tissues from multiple sources of damage including xenobiotic, electrophilic, metabolic, and oxidative stress. Importantly, the aberrant activation or accumulation of NRF2, a common event in many tumors, confers a selective advantage to cancer cells and is associated to malignant progression, therapy resistance, and poor prognosis. Hence, in the last years, NRF2 has emerged as a promising target in cancer treatment and many efforts have been made to identify therapeutic strategies aimed at disrupting its prooncogenic role. By summarizing the results from past and recent studies, in this review, we provide an overview concerning the NRF2/KEAP1 pathway, its biological impact in solid and hematologic malignancies, and the molecular mechanisms causing NRF2 hyperactivation in cancer cells. Finally, we also describe some of the most promising therapeutic approaches that have been successfully employed to counteract NRF2 activity in tumors, with a particular emphasis on the development of natural compounds and the adoption of drug repurposing strategies.

Chronic optogenetic induction of stress granules is cytotoxic and reveals the evolution of ALS-FTD pathology.

This article has been through an editorial process in which the authors decide how to respond to the issues raised during peer review. The Reviewing Editor's assessment is that all the issues have been addressed (see decision letter).

Critical Role of Nrf2 in Experimental Ischemic Stroke.

Ischemic stroke is one of the leading causes of death and long-term disability worldwide; however, effective clinical approaches are still limited. The transcriptional factor Nrf2 is a master regulator in cellular and organismal defense against endogenous and exogenous stressors by coordinating basal and stress-inducible activation of multiple cytoprotective genes. The Nrf2 network not only tightly controls redox homeostasis but also regulates multiple intermediary metabolic processes. Therefore, targeting Nrf2 has emerged as an attractive therapeutic strategy for the prevention and treatment of CNS diseases including stroke. Here, the current understanding of the Nrf2 regulatory network is critically examined to present evidence for the contribution of Nrf2 pathway in rodent ischemic stroke models. This review outlines the literature for Nrf2 studies in preclinical stroke and focuses on the in vivo evidence for the role of Nrf2 in primary and secondary brain injuries. The dynamic change and functional importance of Nrf2 signaling, as well as Nrf2 targeted intervention, are revealed in permanent, transient, and global cerebral ischemia models. In addition, key considerations, pitfalls, and future potentials for Nrf2 studies in preclinical stroke investigation are discussed.

Frailty Level Monitoring and Analysis after a Pilot Six-Week Randomized Controlled Clinical Trial Using the FRED Exergame Including Biofeedback Supervision in an Elderly Day Care Centre.

Background: Frailty is a status of extreme vulnerability to endogenous and exogenous stressors exposing the individual to a higher risk of negative health-related outcomes. Exercise using interactive videos, known as exergames, is being increasingly used to increase physical activity by improving health and the physical function in elderly adults. The purpose of this study is to ascertain the reduction in the degree of frailty, the degree of independence in activities of daily living, the perception of one’s state of health, safety and cardiac healthiness by the exercise done using FRED over a 6-week period in elderly day care centre. Material and Methods: Frail volunteers >65 years of age, with a score of <10 points (SPPB), took part in the study. A study group and a control group of 20 participants respectively were obtained. Following randomisation, the study group (20) took part in 18 sessions in total over 6 months, and biofeedback was recorded in each session. Results: After 6 weeks, 100% of patients from the control group continued evidencing frailty risk, whereas only 5% of patients from the study group did so, with p < 0.001 statistical significance. In the case of the EQ-VAS, the control group worsened (−12.63 points) whereas the study group improved (12.05 points). The Barthel Index showed an improvement in the study group after 6 weeks, with statistically significant evidence and a value of p < 0.003906. Safety compliance with the physical activity exceeded 87% and even improved as the days went by. Discussion: Our results stand out from those obtained by other authors in that FRED is an ad hoc-designed exergame, significantly reduced the presence and severity of frailty in a sample of sedentary elders, thus potentially modifying their risk profile. It in turn improves the degree of independence in activities of daily living and the perception of one’s state of health, proving to be a safe and cardiac healthy exercise. Conclusions: The study undertaken confirms the fact that the FRED game proves to be a valid technological solution for reducing frailty risk. Based on the study conducted, the exergame may be considered an effective, safe and entertaining alternative.

Analysis of novel immune–related genes and microsatellite markers in the transcriptome of Paphia undulata

Increasingly, exogenous stressors such as pathogen infections, variable water conditions, and pollution are resulting in high mortality of Paphia undulata, deleteriously affecting the quality of clam harvests. The foot is a burrowing organ in clams. Physical damage and constant contact with the external environment cause the foot to be highly sensitive to pathogen invasion and water condition variation. In the present study, the foot tissue transcriptome was analyzed to identify genes involved in immune and stress responses. The P. undulata transcriptome included 5 286 668 078 bp reads generated by Illumina Hiseq2000 sequencing and were assembled into 1 785 226 contigs by de novo method. The contigs were clustered into 99 339 transcripts and further grouped into 60 201 unigenes. Of them, 22 260 unigenes were successfully annotated using public databases. Twelve genes that were response to immune and stress were identified with abundant expression levels, including heat shock protein 70, cold shock protein, complement C3, cathepsin L, ubiquitin carboxyl–terminal hydrolase L5, and translationally controlled tumor protein. Furthermore, 566 unigenes were found homologous to genes involved in the immune response systems of pathogen discrimination, signal transduction, and immune effector, such as lectins, toll–like receptors, complement pathway, toll–like receptor signaling pathway, heat shock proteins, antioxidant enzymes, lysozymes, and mucins, indicating that P. undulata could have a complete set of innate immune mechanisms. In addition, 4 270 microsatellite markers (SSRs) were identified from 60 201 unigenes, of which trinucleotide repeats were most abundant and 16 SSRs were tested to be polymorphic. The present study provides a new insight into innate immunity and stress response mechanisms in P. undulata.

Functional significance of channelopathy gene variants in unexplained death.

Determining the cause of unexplained death in all age groups, including infants, is a priority in forensic medicine. The triple risk model proposed for sudden infant death syndrome involves the intersection of three risks: (1) a critical developmental period in homeostatic control (2), exogenous stressors, and (3) a vulnerable infant. Even though sex and age factor into some forms of inherited arrhythmogenic deaths in young individuals and adults, more appropriate a dual-risk disease model for adults involves exogenous stressors and a vulnerable individual. The vulnerability aspect clearly has a genetic component as underscored by a number of recent large-scale and high-throughput genetic testing studies performed in attempt to define the causes of sudden unexplained death. These studies often focus on 'cardiac' and channelopathy genes. Genetic testing often identify lists of rare or ultra-rare nonsynonymous variants, classified according to the ACMG guidelines as 'pathogenic' or 'likely pathogenic', which may form the basis of diagnostic decisions and/or family counseling. However, computer algorithms used to categorize gene variants are not completely accurate and these variants are often not functionally tested to determine their pathogenicity. Due to conflicting computational predictions, a large number of variants are labeled as 'variants of uncertain significance' or VUS. Functional testing of these VUS can greatly assist to reclassify these VUS as 'likely benign' or 'likely pathogenic'. However, functional testing has its limits and by itself cannot be used to determine cause of death. Going forward, computer algorithms must be improved to take account of variants across multiple genes and efforts must be expanded to obtain clinical, familial and segregation data. Forensic genetic testing needs to be held to the same rigorous standards as defined by the NIH Clinical Genome Resource Consortium, where functional evaluation of a channelopathy variant is only one (but important) aspect of the overall picture.

Fuchs Endothelial Corneal Dystrophy Through the Prism of Oxidative Stress.

The corneal endothelium (CE) is vital for maintaining the water balance and clarity of the cornea. The CE is a cell layer that is particularly susceptible to aging because of its postmitotic arrest, high metabolic activity involving pumping of ions, and lifelong exposure to ultraviolet light. Despite gradual age-related cell loss, a sufficient number of CE cells are preserved during the lifespan of an individual. However, in conditions such as Fuchs endothelial corneal dystrophy (FECD), permanent loss of CE cells leads to corneal edema and loss of vision requiring corneal transplantation. FECD is a genetic and oxidative stress disorder manifested by abnormal cell-matrix interactions and expedited cellular aging culminating in cellular death. Because the endothelium has minimal replicative capacity in vivo and an inability to replace its genome, it is particularly prone to cumulative DNA damage acquired throughout life. In FECD, the underlying genetic defects make the CE genome even more vulnerable to this damage, to the point of causing mitochondrial dysfunction, mitochondrial membrane potential loss, and excessive mitophagy activation. Endogenous and exogenous intracellular stressors alter the synthetic footprint of CE cells, leading to endothelial-mesenchymal transition and secretion of aberrant extracellular matrix (in the form of guttae), resembling scar formation in other organs. In turn, the guttae or endothelial scars contribute to a vicious cycle of FECD pathogenesis and, by further inducing endothelial-mesenchymal transition and oxidant-antioxidant imbalance, perpetuate the molecular changes of the degenerating endothelium.

PC06.03 Tumor Mutation Burden - PRO

PC06.03 Tumor Mutation Burden - PRO

Roles of the KEAP1-NRF2 system in mammalian skin exposed to UV radiation

The KEAP1 (Kelch-like ECH-associated protein 1)-NRF2 (NF-E2-related factor 2) system controls the biochemical defense activity against agents toxic to mammals and responds to exogenous and endogenous stressors such as electrophilic and oxidative substances, which can have destructive and genotoxic effects on affected mammalian tissues. Although this system can be activated by various environmental stressors, it remains unclear whether ultraviolet radiation (UVR), which is one of the major environmental agents that has inflammatory and carcinogenic impacts on human skin and eyes, induces NRF2-dependent defense activity. Here, we review the recent progress in the study of the contributions of NRF2 and related factors to protection against UVR. The KEAP1-NRF2 system is not always efficient in responding to UVR, especially to short wavelengths such as UVC/UVB, indicating that UVR is a poor activator of the KEAP1-NRF2 system. However, sustained activation of NRF2 appears to suppress the harmful effects of chronic UVR exposure, such as photoaging of and carcinogenesis in the skin, indicating that NRF2 activation is beneficial for the protection of the skin from the harmful effects of UVR. However, it should be noted that prolonged and strong activation of NRF2 may also have adverse effects on skin, especially in the case of UVR-induced carcinogenesis. We present working models describing mechanisms underlying the involvement of the KEAP1-NRF2 system in skin photoaging and carcinogenesis.