Enriched environment inhibits mouse pancreatic cancer growth and down-regulates the expression of mitochondria-related genes in cancer cells

Digital Therapeutics for Improving Effectiveness of Pharmaceutical Drugs and Biological Products: Preclinical and Clinical Studies Supporting Development of Drug + Digital Combination Therapies for Chronic Diseases

Limitations of pharmaceutical drugs and biologics for chronic diseases (e.g., medication non-adherence, adverse effects, toxicity, or inadequate efficacy) can be mitigated by mobile medical apps, known as digital therapeutics (DTx). Authorization of adjunct DTx by the US Food and Drug Administration and draft guidelines on "prescription drug use-related software" illustrate opportunities to create drug + digital combination therapies, ultimately leading towards drug-device combination products (DTx has a status of medical devices). Digital interventions (mobile, web-based, virtual reality, and video game applications) demonstrate clinically meaningful benefits for people living with Alzheimer's disease, dementia, rheumatoid arthritis, cancer, chronic pain, epilepsy, depression, and anxiety. In the respective animal disease models, preclinical studies on environmental enrichment and other non-pharmacological modalities (physical activity, social interactions, learning, and music) as surrogates for DTx "active ingredients" also show improved outcomes. In this narrative review, we discuss how drug + digital combination therapies can impact translational research, drug discovery and development, generic drug repurposing, and gene therapies. Market-driven incentives to create drug-device combination products are illustrated by Humira® (adalimumab) facing a "patent-cliff" competition with cheaper and more effective biosimilars seamlessly integrated with DTx. In conclusion, pharma and biotech companies, patients, and healthcare professionals will benefit from accelerating integration of digital interventions with pharmacotherapies.

Environmental Enrichment in Cancer as a Possible Tool to Combat Tumor Development: A Systematic Review

This systematic review aims to evaluate the influence of environmental enrichment (EE) on oncological factors in experimental studies involving various types of cancer models. A comprehensive search was conducted in three databases: PubMed (161 articles), Embase (335 articles), and Scopus (274 articles). Eligibility criteria were applied based on the PICOS strategy to minimize bias. Two independent researchers performed the searches, with a third participant resolving any discrepancies. The selected articles were analyzed, and data regarding sample characteristics and EE protocols were extracted. The outcomes focused solely on cancer and tumor-related parameters, including cancer type, description of the cancer model, angiogenesis, tumor occurrence, volume, weight, mice with tumors, and tumor inhibition rate. A total of 770 articles were identified across the three databases, with 12 studies meeting the inclusion criteria for this systematic review. The findings demonstrated that different EE protocols were effective in significantly reducing various aspects of tumor growth and development, such as angiogenesis, volume, weight, and the number of mice with tumors. Furthermore, EE enhanced the rate of tumor inhibition in mouse cancer models. This systematic review qualitatively demonstrates the impacts of EE protocols on multiple parameters associated with tumor growth and development, including angiogenesis, occurrence, volume, weight, and tumor incidence. Moreover, EE demonstrated the potential to increase the rate of tumor inhibition. These findings underscore the importance of EE as a valuable tool in the management of cancer.

The effects of environmental enrichment on voluntary physical activity and muscle mass gain in growing rats

Introduction: Environmental enrichment (EE) for rodents involves housing conditions that facilitate enhanced sensory, cognitive, and motor stimulation relative to standard housing conditions. A recent study suggested that EE induces muscle hypertrophy. However, it remains unclear whether muscle hypertrophy in EE is associated with voluntary physical activity, and the characteristics of muscle adaptation to EE remain unclarified. Therefore, this study investigated whether muscle adaptation to EE is associated with voluntary physical activity, and assessed the changes in the muscle fiber-type distribution and fiber-type-specific cross-sectional area in response to EE. Methods: Wistar rats (6 weeks of age) were randomly assigned to either the standard environment group (n = 10) or the EE group (n = 10). The voluntary physical activity of rats housed in EE conditions was measured using a recently developed three-axis accelerometer. After exposure to the standard or enriched environment for 30 days, the tibialis anterior, extensor digitorum longus, soleus, plantaris, and gastrocnemius muscles were removed and weighed. Immunohistochemistry analysis was performed on the surface (anterior) and deep (posterior) areas of the tibialis anterior and soleus muscles. Results and discussion: The EE group showed increased voluntary physical activity during the dark period compared with the standard environment group (p = 0.005). EE induced muscle mass gain in the soleus muscle (p = 0.002) and increased the slow-twitch muscle fiber cross-sectional area of the soleus muscle (p = 0.025). EE also increased the distribution of high-oxidative type IIa fibers of the surface area (p = 0.001) and type I fibers of the deep area (p = 0.037) of the tibialis anterior muscle. These findings suggest that EE is an effective approach to induce slow-twitch muscle fiber hypertrophy through increased daily voluntary physical activity.

Psychological distress and eustress in cancer and cancer treatment: Advances and perspectives

Facing cancer diagnosis, patients with cancer are prone to psychological stress and consequent psychological disorders. The association between psychological stress and cancer has long been a subject of high interest. To date, preclinical studies have gradually uncovered the promotive effects of psychological distress on tumor hallmarks. In contrast, eustress may exert suppressive effects on tumorigenesis and beneficial effects on tumor treatment, which brings a practicable means and psychosocial perspective to cancer treatment. However, the underlying mechanisms remain incompletely understood. Here, by focusing on the hypothalamic-pituitary-adrenal axis and the sympathetic nervous system, as well as stress-related crucial neurotransmitters and hormones, we highlight the effects of distress and eustress on tumorigenesis, the tumor microenvironment, and tumor treatment. We also discuss the findings of clinical studies on stress management in patients with cancer. Last, we summarize questions that remain to be addressed and provide suggestions for future research directions.

'Invisible actors'-How poor methodology reporting compromises mouse models of oncology: A cross-sectional survey

The laboratory mouse is a key player in preclinical oncology research. However, emphasis of techniques reporting at the expense of critical animal-related detail compromises research integrity, animal welfare, and, ultimately, the translation potential of mouse-based oncology models. To evaluate current reporting practices, we performed a cross-sectional survey of 400 preclinical oncology studies using mouse solid-tumour models. Articles published in 2020 were selected from 20 journals that specifically endorsed the ARRIVE (Animal Research: Reporting of In Vivo Experiments) preclinical reporting guidelines. We assessed reporting compliance for 22 items in five domains: ethical oversight assurance, animal signalment, husbandry, welfare, and euthanasia. Data were analysed using hierarchical generalised random-intercept models, clustered on journal. Overall, reporting of animal-related items was poor. Median compliance over all categories was 23%. There was little or no association between extent of reporting compliance and journal or journal impact factor. Age, sex, and source were reported most frequently, but verifiable strain information was reported for <10% of studies. Animal husbandry, housing environment, and welfare items were reported by <5% of studies. Fewer than one in four studies reported analgesia use, humane endpoints, or an identifiable method of euthanasia. Of concern was the poor documentation of ethical oversight information. Fewer than one in four provided verifiable approval information, and almost one in ten reported no information, or information that was demonstrably false. Mice are the "invisible actors" in preclinical oncology research. In spite of widespread endorsement of reporting guidelines, adherence to reporting guidelines on the part of authors is poor and journals fail to enforce guideline reporting standards. In particular, the inadequate reporting of key animal-related items severely restricts the utility and translation potential of mouse models, and results in research waste. Both investigators and journals have the ethical responsibility to ensure animals are not wasted in uninformative research.

Emerging Roles of the Nervous System in Gastrointestinal Cancer Development

Simple Summary

Nerve–cancer cross-talk has increasingly become a focus of the oncology field, particularly in gastrointestinal (GI) cancers. The indispensable roles of the nervous system in GI tumorigenesis and malignancy have been dissected by epidemiological, experimental animal and mechanistic data. Herein, we review and integrate recent discoveries linking the nervous system to GI cancer initiation and progression, and focus on the molecular mechanisms by which nerves and neural receptor pathways drive GI malignancy.

Abstract

Our understanding of the fascinating connection between nervous system and gastrointestinal (GI) tumorigenesis has expanded greatly in recent years. Recent studies revealed that neurogenesis plays an active part in GI tumor initiation and progression. Tumor-driven neurogenesis, as well as neurite outgrowth of the pre-existing peripheral nervous system (PNS), may fuel GI tumor progression via facilitating cancer cell proliferation, chemoresistance, invasion and immune escape. Neurotransmitters and neuropeptides drive the activation of various oncogenic pathways downstream of neural receptors within cancer cells, underscoring the importance of neural signaling pathways in GI tumor malignancy. In addition, neural infiltration also plays an integral role in tumor microenvironments, and contributes to an environment in favor of tumor angiogenesis, immune evasion and invasion. Blockade of tumor innervation via denervation or pharmacological agents may serve as a promising therapeutic strategy against GI tumors. In this review, we summarize recent findings linking the nervous system to GI tumor progression, set the spotlight on the molecular mechanisms by which neural signaling fuels cancer aggressiveness, and highlight the importance of targeting neural mechanisms in GI tumor therapy.

Increased Expression of Mitochondrial UQCRC1 in Pancreatic Cancer Impairs Antitumor Immunity of Natural Killer Cells via Elevating Extracellular ATP

Pancreatic cancer (PC) is one of the most lethal malignancies characterized by a highly immunosuppressive tumor microenvironment (TME). Previously, we have reported that ubiquinol-cytochrome c reductase core protein I (UQCRC1), a key component of mitochondrial complex III, is generally upregulated in PC and produces extracellular ATP (eATP) to promote PC progression. Here, we sought to investigate whether the oncogenic property of UQCRC1 is generated through its effects on natural killer (NK) cells in the TME. We found that UQCRC1 overexpression in PC cells inhibited cytotoxicity of NK cells, as well as the infiltration of NK cells toward PC, whereas knockdown of UQCRC1 enhanced the cytotoxicity and chemotaxis of NK cells. Adoptive NK cell therapy in the subcutaneous mouse model and CIBERSORTx analysis with human PC specimens confirmed UQCRC1 elicited immunosuppressive effects on NK cells. Such UQCRC1-induced impairment of NK cells was mediated by eATP and its metabolite adenosine via P2Y11R and A2AR, respectively. Mechanistically, we found the UQCRC1/eATP axis reduced the expression of chemokine CCL5 in cancer cells and altered the balance of activating receptor DNAM-1 and inhibitory receptor CD96 on NK-92MI cells, resulting in decreased chemotaxis and exhausted phenotype of NK-92MI cells. Taken together, our study provides the evidence to support a novel mechanism by which energy metabolism change in cancer cells remodels the TME and impedes NK cell surveillance. It also suggests that targeting UQCRC1 may be a potential combined strategy for PC immunotherapy.

The Nervous System Contributes to the Tumorigenesis and Progression of Human Digestive Tract Cancer

Tumors of the gastrointestinal tract are one of the highest incidences of morbidity and mortality in humans. Recently, a growing number of researchers have indicated that nerve fibers and nerve signals participate in tumorigenesis. The current overarching view based on the responses to therapy revealed that tumors are partly promoted by the tumor microenvironment (TME), endogenous oncogenic factors, and complex systemic processes. Homeostasis of the neuroendocrine-immune axis (NEI axis) maintains a healthy in vivo environment in humans, and dysfunction of the axis contributes to various cancers, including the digestive tract. Interestingly, nerves might promote tumor development via multiple mechanisms, including perineural invasion (PNI), central level regulation, NEI axis effect, and neurotransmitter induction. This review focuses on the association between digestive tumors and nerve regulation, including PNI, the NEI axis, stress, and neurotransmitters, as well as on the potential clinical application of neurotherapy, aiming to provide a new perspective on the management of digestive cancers.

Phasic firing of dopaminergic neurons in the ventral tegmental area triggers peripheral immune responses

Dopaminergic neurons in the ventral tegmental area (VTA) play a crucial role in the processing of reward-related information. Recent studies with pharmacological manipulations of VTA neuronal activity demonstrated a VTA-induced immunoenhancement in peripheral organs. Here, to examine the detailed physiological dynamics, we took an optogenetic approach in which VTA dopaminergic neurons were selectively activated with millisecond precision. Optogenetic phasic, rather than tonic, stimulation of VTA dopaminergic neurons increased serum cytokine levels, such as IL-2, IL-4 and TNF-α. These results provide direct evidence to link dopaminergic neuronal phasic firing to peripheral immunity. Next, we tested whether cytokine induction in male mice was boosted by female encounters, a natural condition that induces increased active VTA neurons and gamma power. Female encounters increased serum IL-2 levels, which were abolished by pharmacological inhibition of VTA neuronal activity. Taken together, our results highlight the importance of the brain reward system in the treatment and management of immune-related disorders.

Environmental Enrichment Mitigates Age-Related Metabolic Decline and Lewis Lung Carcinoma Growth in Aged Female Mice

Aging is a complex physiological process that leads to the progressive decline of metabolic and immune function, among other biological mechanisms. As global life expectancy increases, it is important to understand determinants of healthy aging-including environmental and genetic factors-and thus slow the onset or progression of age-related disease. Environmental enrichment (EE) is a housing environment wherein laboratory animals engage with complex physical and social stimulation. EE is a prime model to understand environmental influences on aging dynamics, as it confers an antiobesity and anticancer phenotype that has been implicated in healthy aging and health span extension. Although EE is frequently used to study malignancies in young mice, fewer studies characterize EE-cancer outcomes in older mice. Here, we used young (3-month-old) and aged (14-month-old) female C57BL/6 mice to determine whether EE would be able to mitigate age-related deficiencies in metabolic function and thus alter Lewis lung carcinoma (LLC) growth. Overall, EE improved metabolic function, resulting in reduced fat mass, increased lean mass, and improved glycemic processing; many of these effects were stronger in the aged cohort than in the young cohort, indicating an age-driven effect on metabolic responses. In the aged-EE cohort, subcutaneously implanted LLC tumor growth was inhibited and tumors exhibited alterations in various markers of apoptosis, proliferation, angiogenesis, inflammation, and malignancy. These results validate EE as an anticancer model in aged mice and underscore the importance of understanding environmental influences on cancer malignancy in aged populations. PREVENTION RELEVANCE: Environmental enrichment (EE) serves as a model of complex physical and social stimulation. This study validates EE as an anticancer intervention paradigm in aged mice and underscores the importance of understanding environmental influences on cancer malignancy in aged populations.

An Enriched Environment Alters DNA Repair and Inflammatory Responses After Radiation Exposure

After the Fukushima Daiichi Nuclear Power Plant accident, there is growing concern about radiation-induced carcinogenesis. In addition, living in a long-term shelter or temporary housing due to disasters might cause unpleasant stress, which adversely affects physical and mental health. It's been experimentally demonstrated that "eustress", which is rich and comfortable, has beneficial effects for health using mouse models. In a previous study, mice raised in the enriched environment (EE) has shown effects such as suppression of tumor growth and enhancement of drug sensitivity during cancer treatment. However, it's not yet been evaluated whether EE affects radiation-induced carcinogenesis. Therefore, to evaluate whether EE suppresses a radiation-induced carcinogenesis after radiation exposure, in this study, we assessed the serum leptin levels, radiation-induced DNA damage response and inflammatory response using the mouse model. In brief, serum and tissues were collected and analyzed over time in irradiated mice after manipulating the raising environment during the juvenile or adult stage. To assess the radiation-induced DNA damage response, we performed immunostaining for phosphorylated H2AX which is a marker of DNA double-strand break. Focusing on the polarization of macrophages in the inflammatory reaction that has an important role in carcinogenesis, we performed analysis using tissue immunofluorescence staining and RT-qPCR. Our data confirmed that EE breeding before radiation exposure improved the responsiveness to radiation-induced DNA damage and basal immunity, further suppressing the chronic inflammatory response, and that might lead to a reduction of the risk of radiation-induced carcinogenesis.

Enriched Environment Cues Suggest a New Strategy to Counteract Glioma: Engineered rAAV2-IL-15 Microglia Modulate the Tumor Microenvironment

Several types of cancer grow differently depending on the environmental stimuli they receive. In glioma, exposure to an enriched environment (EE) increases the overall survival rate of tumor-bearing mice, acting on the cells that participate to define the tumor microenvironment. In particular, environmental cues increase the microglial production of interleukin (IL)-15 which promotes a pro-inflammatory (antitumor) phenotype of microglia and the cytotoxic activity of natural killer (NK) cells, counteracting glioma growth, thus representing a virtuous mechanism of interaction between NK cells and microglia. To mimic the effect of EE on glioma, we investigated the potential of creating engineered microglia as the source of IL-15 in glioma. We demonstrated that microglia modified with recombinant adeno-associated virus serotype 2 (rAAV2) carrying IL-15 (rAAV2-IL-15), to force the production of IL-15, are able to increase the NK cells viability in coculture. Furthermore, the intranasal delivery of rAAV2-IL-15 microglia triggered the interplay with NK cells in vivo, enhancing NK cell recruitment and pro-inflammatory microglial phenotype in tumor mass of glioma-bearing mice, and ultimately counteracted tumor growth. This approach has a high potential for clinical translatability, highlighting the therapeutic efficacy of forced IL-15 production in microglia: the delivery of engineered rAAV2-IL-15 microglia to boost the immune response paves the way to design a new perspective therapy for glioma patients.

Enhancing Effects of Environmental Enrichment on the Functions of Natural Killer Cells in Mice

The environment of an organism can convey a powerful influence over its biology. Environmental enrichment (EE), as a eustress model, has been used extensively in neuroscience to study neurogenesis and brain plasticity. EE has also been used as an intervention for the treatment and prevention of neurological and psychiatric disorders with limited clinical application. By contrast, the effects of EE on the immune system are relatively less investigated. Recently, accumulating evidence has demonstrated that EE can robustly impact immune function. In this review, we summarize the major components of EE, the impact of EE on natural killer (NK) cells, EE's immunoprotective roles in cancer, and the underlying mechanisms of EE-induced NK cell regulation. Moreover, we discuss opportunities for translational application based on insights from animal research of EE-induced NK cell regulation.

Environmental activation of a hypothalamic BDNF-adipocyte IL-15 axis regulates adipose-natural killer cells

Physical and social environments influence immune homeostasis within adipose tissue, yet the mechanisms remain poorly defined. We report that an enriched environment (EE) housing modulates the immune cell population in white adipose tissue of mice including an increase in the abundance of natural killer (NK) cells. EE upregulates the expression of IL-15 and its receptor IL-15Rα specifically within mature adipocytes. Mechanistically, we show that hypothalamic brain-derived neurotrophic factor (BDNF) upregulates IL-15 production in adipocytes via sympathetic β-adrenergic signaling. Overexpressing BDNF mediated by recombinant adeno-associated virus (rAAV) vector in the hypothalamus expands adipose NK cells. Conversely, inhibition of hypothalamic BDNF signaling via gene transfer of a dominant negative TrkB receptor suppresses adipose NK cells. In white adipose tissue, overexpression of IL-15 using an adipocyte-specific rAAV vector stimulates adipose NK cells and inhibits the progression of subcutaneous melanoma, whereas local IL-15 knockdown blocks the EE effect. These results suggest that bio-behavioral factors regulate adipose NK cells via a hypothalamic BDNF-sympathoneural-adipocyte IL-15 axis. Targeting this pathway may have therapeutic significance for cancer.

Stress-related hormone reduces autophagy through the regulation of phosphatidylethanolamine in breast cancer cells

Background

An increasing number of studies indicate that adrenergic signaling plays a fundamental role in tumor progression and metastasis induced by chronic stress. However, despite the growing attention, an understanding of the mechanisms linking chronic stress and cancer is still insufficient.

Methods

Western blot analysis and transmission electron microscopy (TEM) were used to observe the changes in autophagy level in a breast cancer cell line (MCF-7) after epinephrine treatment. Non-targeted metabolomics was also used to detect MCF-7 metabolites after epinephrine treatment. The xenograft model was used to detect the level of autophagy after epinephrine intervention.

Results

The results showed that epinephrine treatment reduced the autophagy level of breast cancer cells. Epinephrine changed the level of phosphatidylethanolamine (PE) in breast cancer cells as detected by non-targeted metabolomics. Epinephrine also changed autophagy in breast cancer cells by decreasing the level of PE in cells. When autophagy decreased, the invasion and migration of breast cancer cells increased in vitro, and the progression of breast cancer accelerated in vivo.

Conclusions

These findings suggest that stress-related hormones affect the tumor progression of breast cancer. Therefore, strengthening the emotional management strategies of patients during the process of antitumor treatment as a supplement to the existing treatments may be beneficial.

Adipose PTEN acts as a downstream mediator of a brain-fat axis in environmental enrichment

Background/Objectives

Environmental enrichment (EE) is a physiological model to investigate brain-fat interactions. We previously discovered that EE activates the hypothalamic-sympathoneural adipocyte (HSA) axis via induction of brain-derived neurotrophic factor (BDNF), thus leading to sympathetic stimulation of white adipose tissue (WAT) and an anti-obesity phenotype. Here, we investigate whether PTEN acts as a downstream mediator of the HSA axis in the EE.

Methods

Mice were housed in EE for 4- and 16-week periods to determine how EE regulates adipose PTEN. Hypothalamic injections of adeno-associated viral (AAV) vectors expressing BDNF and a dominant negative form of its receptor were performed to assess the role of the HSA axis in adipose PTEN upregulation. A β-blocker, propranolol, and a denervation agent, 6-hydroydopamine, were administered to assess sympathetic signaling in the observed EE-PTEN phenotype. To determine whether inducing PTEN is sufficient to reproduce certain EE adipose remodeling, we overexpressed PTEN in WAT using an AAV vector. To determine whether adipose PTEN is necessary for the EE-mediated reduction in adipocyte size, we injected a rAAV vector expressing Cre recombinase to the WAT of adult PTEN^flox mice and placed the mice in EE.

Results

EE upregulated adipose PTEN expression, which was associated with suppression of AKT and ERK phosphorylation, increased hormone-sensitive lipase (HSL) phosphorylation, and reduced adiposity. PTEN regulation was found to be controlled by the HSA axis—with the hypothalamic BDNF acting as the upstream mediator—and dependent on sympathetic innervation. AAV-mediated adipose PTEN overexpression recapitulated EE-mediated adipose changes including suppression of AKT and ERK phosphorylation, increased HSL phosphorylation, and reduced adipose mass, whereas PTEN knockdown blocked the EE-induced reduction of adipocyte size.

Conclusions

These data suggest that adipose PTEN responds to environmental stimuli and serves as downstream mediator of WAT remodeling in the EE paradigm, resulting in decreased adipose mass and decreased adipocyte size.

•

Environmental enrichment (EE) induces adipose PTEN expression and is associated with (1) suppression of AKT phosphorylation, (2) increased hormone-sensitive lipase phosphorylation, and (3) decreased adiposity

•

The hypothalamic-sympathoneural-adipocyte (HSA) axis mediates EE-induced adipose PTEN

•

rAAV-mediated gene delivery of PTEN to adipose tissues mimics EE-related adipose remodeling

•

Knockdown of adipose PTEN blocks EE-induced reductions in adipocyte size

Environmental Complexity and Research Outcomes

Environmental complexity is an experimental paradigm as well as a potential part of animals' everyday housing experiences. In experimental uses, researchers add complexity to stimulate brain development, delay degenerative brain changes, elicit more naturalistic behaviors, and test learning and memory. Complexity can exacerbate or mitigate behavioral problems, give animals a sense of control, and allow for expression of highly driven, species-typical behaviors that can improve animal welfare. Complex environments should be designed thoughtfully with the animal's natural behaviors in mind, reported faithfully in the literature, and evaluated carefully for unexpected effects.

Systemic Regulation of Cancer Development by Neuro-Endocrine-Immune Signaling Network at Multiple Levels

The overarching view of current tumor therapies simplifies cancer to a cell-biology problem in which neoplasms are caused solely by malignant cells and the exploration of carcinogenesis and tumor progression largely focuses on somatic mutations and other genetic abnormalities of cancer cells. The limited therapeutic response indicates that cancer is driven not only by endogenous oncogenic factors and reciprocal interactions within the tumor microenvironment, but also by complex systemic processes. Homeostasis is the fundamental premise of health, and is maintained by systemic regulation of neuro-endocrine-immune axis. Cancer is also a systemic disease that manifested by dysfunction of the nervous, endocrine, and immune systems. Multiple axes of regulation exist in cancer, including central-, organ-, and microenvironment-level manipulation. At each specific regulatory level, the tridirectional communication among the nervous, endocrine, and immune factors transmit flexible signaling to induce proliferation, invasion, reprogrammed metabolism, therapeutic resistance, and other malignant phenotypes of cancer cells, resulting in the extremely poor prognosis of this lethal disease. Understanding this coordinated signaling network will enable the development of new approaches for cancer treatment via behavioral and pharmacological interventions.

Regulation of aging and cancer by enhanced environmental activation of a hypothalamic-sympathoneural-adipocyte axis

Social and environmental factors impact cancer and energy balance profoundly. Years ago, our lab established the existence of a novel brain-fat interaction we termed the "hypothalamic-sympathoneural-adipocyte (HSA) axis", through which complex environmental stimuli provided by an enriched environment regulate body composition, energy balance, and development of cancer. We have spent a significant portion of the past decade to further characterize the broad health benefits of an enriched environment (for example, leanness, enhanced immune function, and cancer resistance), and to identify mediators in the brain and periphery along the HSA axis. This review summarizes our recent work regarding the interface between endocrinology, immunology, cancer biology, aging, and neuroscience. We will discuss the interplay between these systemic phenomena and how the HSA axis can be targeted for regulation of cancer and aging.

Stress and cancer. Part II: Therapeutic implications for oncology

Accumulated evidence has confirmed the ability of stress to promote the induction and progression of cancer (for review see Stress and cancer. Part I: Mechanisms mediating the effect of stressors on cancer). In support of this, data from clinical trials utilizing approaches that reduce stress-related signaling have shown prolonged survival of cancer patients. Therefore, the question has arisen as to how we can utilize this knowledge in the daily treatment of cancer patients. The main aim of this review is to critically analyze data from studies utilizing psychotherapy or treatment by β-blockers on the survival of cancer patients. Because these approaches, especially treatment by β-blockers, have been routinely used in clinical practice for decades in the treatment of non-cancer patients, their wider introduction into oncology might be realized in the near future.

Improvements to Healthspan Through Environmental Enrichment and Lifestyle Interventions: Where Are We Now?

Environmental enrichment (EE) is an experimental paradigm that is used to explore how a complex, stimulating environment can impact overall health. In laboratory animal experiments, EE housing conditions typically include larger-than-standard cages, abundant bedding, running wheels, mazes, toys, and shelters which are rearranged regularly to further increase stimulation. EE has been shown to improve multiple aspects of health, including but not limited to metabolism, learning and cognition, anxiety and depression, and immunocompetence. Recent advances in lifespan have led some researchers to consider aging as a risk factor for disease. As such, there is a pressing need to understand the processes by which healthspan can be increased. The natural and predictable changes during aging can be reversed or decreased through EE and its underlying mechanisms. Here, we review the use of EE in laboratory animals to understand mechanisms involved in aging, and comment on relative areas of strength and weakness in the current literature. We additionally address current efforts toward applying EE-like lifestyle interventions to human health to extend healthspan. Although increasing lifespan is a clear goal of medical research, improving the quality of this added time also deserves significant attention. Despite hurdles in translating experimental results toward clinical application, we argue there is great potential in using features of EE toward improving human healthy life expectancy or healthspan, especially in the context of increased global longevity.

Enriched Environment Decelerates the Development of Endometriosis in Mouse

We tested the hypothesis that enriched environment (EE), consisting of enlarged space, and increased physical activity and social interactions, hinders the development of endometriosis through attenuated adrenergic signaling, enhanced autophagy, and reduced leptin levels. Two mouse experiments were performed. In Experiment 1, 40 female Balb/C mice were randomly divided into four equal-sized groups, the SE (standard environment), EE, p-EE (EE instituted after endometriosis induction), and the d-EE (SE housing but received uterine fragments from EE donors) groups. Housing intervention was initiated 3 weeks before the induction of endometriosis and continued for 3 weeks after induction. In Experiment 2, 20 female mice were randomly divided into SE and EE groups, and the plasma leptin levels were measured. We measured lesion weight and hotplate latency and performed Masson trichrome staining as well as immunohistochemistry analysis of β2 adrenergic receptor (ADRB2), dopamine receptor D2 (DRD2), vascular endothelial growth factor (VEGF), and microtubule-associated protein light chain 3 (LC3). We found that EE reduced the lesion weight by 40.8% as compared with SE mice, but the reduction in p-EE and d-EE mice did not reach statistical significance. EE significantly reduced staining levels of ADRB2 and VEGF as well as the extent of lesional fibrosis but increased staining levels of LC3 and DRD2 in lesions as compared with the SE group. EE mice had reduced plasma leptin levels as compared with SE mice. Thus, EE decelerates the development of endometriosis and fibrogenesis and improved generalized hyperalgesia, possibly through increased DRD2 expression but decreased expression of ADRB2 and VEGF as well as enhanced autophagy and reduced leptin level.

Mitochondrial Protein UQCRC1 is Oncogenic and a Potential Therapeutic Target for Pancreatic Cancer

Purpose: Pancreatic ductal adenocarcinoma (PDAC) is a malignant disease with a poor prognosis. One prominent aspect of PDAC that contributes to its aggressive behavior is its altered cellular metabolism. The aim of this study was to characterize the oncogenic effects of ubiquinol-cytochrome c reductase core protein I (UQCRC1), a key component of mitochondrial complex III, in PDAC development and to assess its potential as a therapeutic target for PDAC.

Experimental Design: The expression of UQCRC1 in human PDAC tissues and p48-Cre/p53Flox/WT/LSL-KrasG12D (KPC) mouse pancreatic intraepithelial neoplasias (PanINs) was determined by immunohistochemistry. The role of UQCRC1 in promoting PDAC growth was evaluated in vitro in PANC-1 and CFPAC-1 cells and in vivo in transplanted mouse models of PDAC. Extracellular flux and RNA-Seq analyses were applied to investigate the mechanism of UQCRC1 in the regulation of mitochondrial metabolism and PDAC cell growth. The therapeutic potential of UQCRC1 in PDAC was assessed by knockdown of UQCRC1 using an RNA interference approach.

Results: UQCRC1 expression showed a gradual increase during the progression from PanIN stages to PDAC in KPC mice. Elevated expression of UQCRC1 was observed in 72.3% of PDAC cases and was correlated with poor prognosis of the disease. UQCRC1 promoted PDAC cell growth in both in vitro experiments and in vivo subcutaneous and orthotopic mouse models. UQCRC1 overexpression resulted in increased mitochondrial oxidative phosphorylation (OXPHOS) and ATP production. The overproduced ATP was released into the extracellular space via the pannexin 1 channel and then functioned as an autocrine or paracrine agent to promote cell proliferation through the ATP/P2Y2-RTK/AKT axis. UQCRC1 knockdown or ATP release blockage could effectively inhibit PDAC growth.

Conclusion: UQCRC1 has a protumor function and may serve as a potential prognostic marker and therapeutic target for PDAC.

Environmental enrichment improves metabolic and behavioral health in the BTBR mouse model of autism

BTBR T + Itpr3tf/J (BTBR) mice are an Autism Spectrum Disorder (ASD)-like model that exhibit behavioral and physiological deficits similar to those observed in patients with ASD. While behavioral therapy is a first line of treatment in ASD patients, comparable non-pharmacological treatments are less explored in murine models. Here, we administer a bio-behavioral intervention for BTBR mice by way of environmental enrichment (EE) - an experimental housing paradigm previously shown to improve systemic metabolism, learning/memory, anxious behavior, neurogenesis, locomotion, and immunocompetence in C57BL/6 mice. Juvenile BTBR mice were randomized to standard or EE housing and were subjected to metabolic and behavioral assessments up to 17 weeks. Following EE exposure, we report an EE-induced metabolic and behavioral phenotype. Male BTBR mice responded metabolically to EE, displaying reduced adiposity, increased lean mass, improved glycemic control, and decreased circulating leptin. The gene expressions of brain-derived neurotrophic factor (Bdnf) and its receptor (Ntrk2/TrkB) were upregulated in several brain areas in EE-BTBR males. EE-BTBR females showed modest reduction of adiposity and no changes in glycemic control, circulating leptin, or Bdnf/Ntrk2 gene expression. With regard to behavior, EE resulted in decreased anxiety, and increased social affiliation. Together, these results suggest that EE improves metabolic and behavioral health in BTBR mice.

A simplified enriched environment increases body temperature and suppresses cancer progression in mice

Mice housed in an enriched environment (EE) have inhibited tumor development because of eustress (positive stress) stimulation. However, the mechanisms underlying increased cancer resistance in EEs remain unclear; this may be due to poor reproducibility of the results because of the complicated EE assembly requirements. In this study, we examined the effects of a simplified EE (sEE) model, consisting only of a nesting shelter and a running wheel, on cancer development in mice. We found that, similar to the complex EE, the sEE promoted motor function and alleviated anxiety in mice. Moreover, the mice housed in the sEE showed inhibited tumor growth and metastasis in addition to a higher average body temperature (especially at the point of transition from light to darkness). Furthermore, mice in the sEE had a decreased brown adipose tissue (BAT) mass, with a significant upregulation of the Ucp1 and Adrb3 genes (which encode uncoupling protein 1 and β-adrenergic receptor, respectively) observed in the BAT at the point of transition from light to darkness. An antibody against the immune checkpoint protein programmed cell death 1 was also found to have an additive effect with the sEE against tumor development. Our findings indicate that the established sEE model may be a useful tool for studying the antitumor effects of eustress and can potentially introduce new avenues for cancer prevention and treatment.

A Fragrant Environment Containing α-Pinene Suppresses Tumor Growth in Mice by Modulating the Hypothalamus/Sympathetic Nerve/Leptin Axis and Immune System

The environment is thought to affect outcomes in patients with cancer; however, this relationship has not been proven directly. Recently, an enriched environment, as a model of a positive environment, has been shown to suppress tumor growth by lowering leptin production through a pathway involving the hypothalamus/sympathetic nerve/leptin axis. We previously reported that a fragrant environment (FE) containing α-pinene suppressed tumor growth in mice; however, the underlying mechanism has not been elucidated. Accordingly, in this study, we investigated changes in the neuroendocrine and immune systems following exposure to an FE. Mice were exposed to α-pinene (5 h/day) for 4 weeks prior to tumor implantation with murine melanoma cells and 3 weeks after transplantation. In addition to the evaluation of tumor growth, the blood, spleen, and hypothalamus were collected 3 weeks after transplantation, and neuroendocrinological and immunological parameters were measured. Tumor size was ~40% smaller in mice exposed to FE. Moreover, plasma noradrenaline concentrations, which reflected sympathetic nervous activity, tended to increase, and leptin levels were significantly decreased in FE-exposed mice. Levels of stress hormones, such as plasma corticosterone and adrenaline, did not change in the 2 groups. In the hypothalamus, brain-derived neurotrophic factor protein levels and glucose-1-phosphate concentrations were decreased in the FE group. Additionally, numbers of B cells, CD4⁺ T cells, CD8⁺ T cells, and natural killer cells increased in the FE-exposed mice. These neurohormonal and immunological changes in the FE-exposed mice suggested that the FE may activate the hypothalamus/sympathetic nerve/leptin axis and immune system, thereby retarding tumor growth.

Manipulation of Ambient Housing Temperature To Study the Impact of Chronic Stress on Immunity and Cancer in Mice

Mice are the preeminent research organism in which to model human diseases and study the involvement of the immune response. Rapidly accumulating evidence indicates a significant involvement of stress hormones in cancer progression, resistance to therapies, and suppression of immune responses. As a result, there has been a concerted effort to model human stress in mice. In this article, we discuss recent literature showing how mice in research facilities are chronically stressed at baseline because of environmental factors. Focusing on housing temperature, we suggest that the stress of cool housing temperatures contributes to the impact of other imposed experimental stressors and therefore has a confounding effect on mouse stress models. Furthermore, we propose that manipulation of housing temperature is a useful approach for studying the impact of chronic stress on disease and the immune response and for testing therapeutic methods of reducing the negative effects of chronic stress.

Minimum environmental enrichment is effective in activating antitumor immunity to transplanted tumor cells in mice

Studies of environmental enrichment are progressing in the fields of nervous system, stress and exercise. Recently, housing in enriched environment have shown to influence to carcinogenesis and life span. However, the study for antitumor effect of environmental enrichment are difficult to reproduce due to the complexity of the experimental technique. Thus, a simpler experiment system is needed for antitumor study using environmental enrichment. In this research, we propose a minimum environmental enrichment, which is an experimental system by placing one mouse igloo which is normally used as a mouse shelter in the rearing environment. The experimental system of minimum environmental enrichment is not only easy to reproduce but also have enhanced activity to suppress the growth of transplanted tumor significantly. It was found that the activation of NK cells is involved also in the immune system related to tumor immunity of minimum environmental enrichment. Because minimum environmental enrichment is effective in activating antitumor immunity to transplanted tumor cells in mice, we believe this will be useful for promoting antitumor studies using environmental enrichment.

Enriched environment inhibits breast cancer progression in obese models with intact leptin signaling

Obesity is becoming a global epidemic and is a risk factor for breast cancer. Environmental enrichment (EE), a model recapitulating an active lifestyle, leads to leanness, resistance to diet-induced obesity (DIO) and cancer. One mechanism is the activation of the hypothalamic-sympathoneural-adipocyte (HSA) axis. This results in the release of norepinephrine onto adipose tissue inducing a drop of leptin. This study aimed to test the effects of EE on breast cancer onset and progression while considering the effect of leptin by utilizing the transgenic MMTV-PyMT model as well as several models of varied leptin signaling. EE was highly effective at reducing weight gain, regardless of the presence of leptin. However, the effects of EE on tumor progression were dependent on leptin signaling. EE decreased leptin and reduced mammary tumor growth rate in MMTV-PyMT spontaneous and DIO transplantation models; in contrast, the absence of leptin in ob/ob mice resulted in increased tumor growth likely due to elevated norepinephrine levels. Our results suggest that the microenvironment is critical in breast tumorigenesis and that the drop in leptin is an important peripheral mediator of the EE anti-breast cancer effects, offsetting the potential pro-tumorigenic effects of norepinephrine responding to a complex environment.

Long-term environmental enrichment affects microglial morphology in middle age mice

Aging is associated with increased central nervous system inflammation, in large part due to dysfunctional microglia. Environmental enrichment (EE) provides a model for studying the dynamics of lifestyle factors in the development of age-related neuroinflammation and microglial dysfunction. EE results in improvements in learning and memory, metabolism, and mental health in a variety of animal models. We recently reported that implementing EE in middle age promotes healthy aging. In the present study, we investigated whether EE influences microglial morphology, and whether EE is associated with changes in expression of microglial and neuroinflammatory markers. Inflammatory cytokines and MHC-II were reduced following 12-month EE in 10-month-old mice. Long-term EE for 7.5 months resulted in broad increases in Iba1 expression in hippocampus, hypothalamus, and amygdala detected by immunohistochemistry. Quantification of microglial morphology reveal both hypertrophy and ramification in these three brain regions, without increases in microglial cell density. These data indicate that long-term EE implemented in middle age results in a microglial state distinct from that of normal aging in standard laboratory housing, in specific brain regions, associated with reduced neuroinflammatory markers and improvement of systemic metabolism.

Enriched environment alleviates stress-induced dry-eye through the BDNF axis

The number of patients with dry eye disease (DED) is increasing, and DED has become an urgent public health problem. A comorbidity of mental disorders has been reported in DED patients. We hypothesized that physical and psychological stressors impair tear secretion. To examine the relationship between stress loading and decreased tear secretion, we established a stress-induced DED mouse model, which permitted us to address the underlying mechanism of pathogenesis and resilience. Enriched environment (EE) was an effective intervention to prevent and alleviate stress-induced decreased tear secretion. Because stress loading resulted in decreased brain-derived neurotrophic factor (BDNF) expression while EE resulted in increased expression, we focused on the role of BDNF in tear secretion. Using two distinct Bdnf gene knockdown mice, we evaluated whether BDNF was a deterministic factor in regulating tear secretion in healthy and stressed conditions. Bdnf knockdown mice showed decreased basal tear secretion and loss of stress tolerance by EE for tear secretion. These results suggest that BDNF expression is related to tear secretion and to the pathology of DED.

Exposure to an enriched environment promotes the terminal maturation and proliferation of natural killer cells in mice

The maturation of natural killer (NK) cells is critical for the acquisition of robust effector functions and the immune response to tumors. However, the influence of psychological stress on NK-cell maturation remains unknown. In this study, we investigated the alteration of NK-cell maturation in response to enriched environment (EE) exposure, which induced eustress, or positive stress, in mice. Analysis of markers representing distinct mature stages revealed that EE promoted the terminal maturation of NK cells both centrally in the bone marrow and peripherally in the spleen and blood. Additionally, EE increased CD27⁺ immature and intermediate-mature NK cell proliferation in the bone marrow. Furthermore, EE exposure brought about a similar promoting effect on NK-cell maturation in tumor-bearing mice. In tumor-bearing mice, EE substantially enhanced the proliferative potential of splenic CD27⁺ NK cells compared to those in the bone marrow. EE-housed mice displayed a tumor-resistant phenotype and an increased proportion of intratumoral NK cells, especially CD11b⁺ CD27^- mature NK cells, while splenectomy abolished the tumor-retardant effect caused by EE and EE-induced NK-cell infiltration into tumors. Given that our previous study demonstrated an important role for NK cells in EE-induced tumor inhibition, the findings of this study further indicate that the enhanced maturation and proliferation of splenic NK cells may contribute to EE-induced tumor inhibition to some extent. Taken together, the results of this study suggest a positive modulating effect of environment-induced eustress on NK-cell maturation, with potential implications for understanding how eustress boosts NK-cell antitumor immunity.

Excessive mitochondrial fragmentation triggered by erlotinib promotes pancreatic cancer PANC-1 cell apoptosis via activating the mROS-HtrA2/Omi pathways

Background

Mitochondrial fragmentation drastically regulates the viability of pancreatic cancer through a poorly understood mechanism. The present study used erlotinib to activate mitochondrial fragmentation and then investigated the downstream events that occurred in response to mitochondrial fragmentation.

Methods

Cell viability and apoptosis were determined via MTT assay, TUNEL staining and ELISA. Mitochondrial fragmentation was measured via an immunofluorescence assay and qPCR. siRNA transfection and pathway blockers were used to perform the loss-of-function assays.

Results

The results of our study demonstrated that erlotinib treatment mediated cell apoptosis in the PANC-1 pancreatic cancer cell line via evoking mitochondrial fragmentation. Mechanistically, erlotinib application increased mitochondrial fission and reduced mitochondrial fusion, triggering mitochondrial fragmentation. Subsequently, mitochondrial fragmentation caused the overproduction of mitochondrial ROS (mROS). Interestingly, excessive mROS induced cardiolipin oxidation and mPTP opening, finally facilitating HtrA2/Omi liberation from the mitochondria into the cytoplasm, where HtrA2/Omi activated caspase-9-dependent cell apoptosis. Notably, neutralization of mROS or knockdown of HtrA2/Omi attenuated erlotinib-mediated mitochondrial fragmentation and favored cancer cell survival.

Conclusions

Together, our results identified the mROS-HtrA2/Omi axis as a novel signaling pathway that is activated by mitochondrial fragmentation and that promotes PANC-1 pancreatic cancer cell mitochondrial apoptosis in the presence of erlotinib.

Electronic supplementary material

The online version of this article (10.1186/s12935-018-0665-1) contains supplementary material, which is available to authorized users.

Implementation of environmental enrichment after middle age promotes healthy aging

With increases in life expectancy, it is vital to understand the dynamics of aging, their interaction with lifestyle factors, and the connections to age-related disease processes. Our work on environmental enrichment (EE), a housing environment boosting mental health, has revealed a novel anticancer and anti-obesity phenotype mediated by a brain-fat axis: the hypothalamic-sympathoneural-adipocyte (HSA) axis in young animals. Here we investigated EE effects on healthspan and lifespan when initiated after middle age. Short-term EE for six weeks activated the HSA axis in 10-month-old mice. Long-term EE for twelve months reduced adiposity, improved glucose tolerance, decreased leptin levels, enhanced motor abilities, and inhibited anxiety. In addition to adipose remodeling, EE decreased age-related liver steatosis, reduced hepatic glucose production, and increased glucose uptake by liver and adipose tissue contributing to the improved glycemic control. The EE-induced liver modulation was associated with a suppression of protein kinase Cε. Moreover, EE down-regulated the expression of inflammatory genes in the brain, adipose, and liver. EE initiated at 18-month of age significantly improved glycemic control and showed a trend of positive impact on mean lifespan. These data suggest that EE induces metabolic and behavioral adaptations that are shared by factors known to increase healthspan and lifespan.

Environmental enrichment and mouse models: Current perspectives

The provision of environmental enrichment to numerous species of laboratory animals is generally considered routine husbandry. However, mouse enrichment has proven to be very complex due to the often contradictory outcomes (animal health and welfare, variability in scientific data, etc.) associated with strain, age of the animal when enrichment is provided, gender of the animal, scientific use of the animal, and other housing attributes. While this has led to some suggesting that mice should not be provided enrichment, more recently opinion is trending toward acknowledging that enrichment actually normalizes the animal and data obtained from a mouse living in a barren environment are likely not to be representative or even reliable. This article offers an overview of the types of impact enrichment can have on various strains of mice and demonstrates that enrichment not only has a role in mouse husbandry, but also can lead to new areas of scientific enquiry in a number of different fields.

Depression induces poor prognosis associates with the down-regulation brain derived neurotrophic factor of serum in advanced small cell lung cancer

Patients with lung cancer often experience a state of depression, and these conditions may severely affect their quality of life (QoL) and prescription compliance. The current study was conducted to delineate the complex links between depression and the prognosis of patients with small cell lung cancer (SCLC) and the underlying mechanism was also explored.186 patients who received platinum-based chemotherapy for newly diagnosed stage III or stage IV SCLC were enrolled. The Self-Rating Depression Scale (SDS) questionnaire was completed the day before the start of chemotherapy to assess the depression status of the patients. Patients with stage IV SCLC or lower BMI have higher depression scores. In terms of the adverse effects of chemotherapy, depression severely decreases patient tolerance to chemotherapy and their QoL score (R2 = 0.2385) and is also associated with severe vomiting (P < 0.001), leukopenia (R2 = 0.2332), and prolonged hospital stay (R2 = 0.1961). More importantly, severe depression reduces the PFS (R2 = 0.1943) and OS (P < 0.01) of the patients. We found that patients with severe depression displayed a downregulated level of serum BDNF and that the level of serum BDNF was highly correlated with the OS of the patients (R2 = 0.2292). Using the MTT cell viability assay in vitro, we observed that cotreatment with BDNF clearly enhanced the chemosensitivity of NCI-H69 tumor cells to Cisplatin and induced the downregulation of ABCG2.Based on this evidence, it appears that a relationship does exist between depression and prognosis in SCLC and that the mechanism by which depression affects prognosis is achieved via the downregulation of BDNF expression.

Unbridle biomedical research from the laboratory cage

Many biomedical research studies use captive animals to model human health and disease. However, a surprising number of studies show that the biological systems of animals living in standard laboratory housing are abnormal. To make animal studies more relevant to human health, research animals should live in the wild or be able to roam free in captive environments that offer a natural range of both positive and negative experiences. Recent technological advances now allow us to study freely roaming animals and we should make use of them.

Signaling Pathways in Thyroid Cancer

The morbidity of thyroid cancer is increasing gradually year by year, showing an increasing tendency in nationality, sex, age, tumor size, and tumor staging. The changes of thyroid cell genes, signaling pathways, and related molecular dysfunction promote the occurrence, development, invasion, and metastasis of thyroid cancer. Surgical operation, radioiodine, and endocrinotherapy models can achieve a better prognosis for most patients with thyroid cancer. Although targeted therapeutic drugs bring possible therapeutic opportunities for refractory thyroid cancer, there is a great gap between their predictive value and their actual efficacy. Currently, there is still no completely effective drug for the treatment. Based on the signaling pathways, the "reclaim therapy" for residual tumor and systemic intervention aims to increase anticancer ability and to encourage new directions and thoughts in the treatment of refractory thyroid cancer.

Enriching the Housing Environment for Mice Enhances Their NK Cell Antitumor Immunity via Sympathetic Nerve-Dependent Regulation of NKG2D and CCR5

Mice housed in an enriched environment display a tumor-resistant phenotype due to eustress stimulation. However, the mechanisms underlying enriched environment-induced protection against cancers remain largely unexplained. In this study, we observed a significant antitumor effect induced by enriched environment in murine pancreatic cancer and lung cancer models. This effect remained intact in T/B lymphocyte-deficient Rag1^-/- mice, but was nearly eliminated in natural killer (NK) cell-deficient Beige mice or in antibody-mediated NK-cell-depleted mice, suggesting a predominant role of NK cells in enriched environment-induced tumor inhibition. Exposure to enriched environment enhanced NK-cell activity against tumors and promoted tumoral infiltration of NK cells. Enriched environment increased the expression levels of CCR5 and NKG2D (KLRK1) in NK cells; blocking their function effectively blunted the enriched environment-induced enhancement of tumoral infiltration and cytotoxic activity of NK cells. Moreover, blockade of β-adrenergic signaling or chemical sympathectomy abolished the effects of enriched environment on NK cells and attenuated the antitumor effect of enriched environment. Taken together, our results provide new insight into the mechanism by which eustress exerts a beneficial effect against cancer. Cancer Res; 77(7); 1611-22. ©2017 AACR.

The Impact of Housing Temperature-Induced Chronic Stress on Preclinical Mouse Tumor Models and Therapeutic Responses: An Important Role for the Nervous System

In the last 10-15 years, there has been a recognition that the catecholamines (norepinephrine, NE, and epinephrine, Epi) released by the sympathetic nervous system under stressful conditions promote tumor growth through a variety of mechanisms. Tumors recruit autonomic nerves during their development and NE is then released locally in the tumor microenvironment (TME). Acting through adrenergic receptors present on a variety of cells in the TME, NE and Epi induce proliferation, resistance to apoptosis, epithelial to mesenchymal transition, metastasis of tumor cells, angiogenesis, and inflammation in the TME. These pre-clinical studies have been conducted in mouse models whose care and housing parameters are outlined in "The Guide for the Care and Use of Laboratory Animals [1]. In particular, the Guide mandates that mice be housed at standardized sub-thermoneutral temperatures; however, this causes a state of chronic cold-stress and elevated levels of NE. Although mice are able to maintain a normal body temperature when kept at these cool temperatures, it is becoming clear that this cold-stress is sufficient to activate physiological changes which affect experimental outcomes. We find that when mice are housed under standard, sub-thermoneutral temperatures (~22 °C, ST), tumor growth is significantly greater than when mice are housed at thermoneutrality (~30 °C TT). We also find that the anti-tumor immune response is suppressed at ST and this immunosuppression can be reversed by housing mice at TT or by administration of propranolol (a β-adrenergic receptor antagonist) to mice housed at ST. Furthermore, at ST tumors are more resistant to therapy and can also be sensitized to cytotoxic therapies by housing mice at TT or by treating mice with propranolol. The implications of these observations are particularly relevant to the way in which experiments conducted in preclinical models are interpreted and the findings implemented in the clinic. It may be that the disappointing failure of many new therapies to fulfill their promise in the clinic is related to an incomplete preclinical assessment in mouse models. Further, an expanded understanding of the efficacy of a therapy alone or in combination obtained by testing under a wider range of conditions would better predict how patients, who are under various levels of stress, might respond in a clinical setting. This may be particularly important to consider since we now appreciate that long term outcome of many therapies depends on eliciting an immune response.It is clear that the outcome of metabolic experiments, immunological investigations and therapeutic efficacy testing in tumors of mice housed at ST is restricted and expanding these experiments to include results obtained at TT may provide us with valuable information that would otherwise be overlooked.

Environmental and Genetic Activation of Hypothalamic BDNF Modulates T-cell Immunity to Exert an Anticancer Phenotype

Macroenvironmental factors, including a patient's physical and social environment, play a role in cancer risk and progression. Our previous studies show that living in an enriched environment (EE) providing complex stimuli confers an anticancer phenotype in mice mediated, in part by a specific neuroendocrine axis, with brain-derived neurotrophic factor (BDNF) as the key brain mediator. Here, we investigated how an EE modulated T-cell immunity and its role in the EE-induced anticancer effects. Our data demonstrated that CD8 T cells were required to mediate the anticancer effects of an EE in an orthotropic model of melanoma. In secondary lymphoid tissue (SLT), an EE induced early changes in the phenotype of T-cell populations, characterized by a decrease in the ratio of CD4 T helper to CD8 cytotoxic T lymphocytes (CTL). Overexpression of hypothalamic BDNF reproduced EE-induced T-cell phenotypes in SLT, whereas knockdown of hypothalamic BDNF inhibited EE-induced immune modulation in SLT. Both propranolol and mifepristone blocked the EE-associated modulation of CTLs in SLT, suggesting that both the sympathetic nervous system and the hypothalamic-pituitary-adrenal axis were involved. Our results demonstrated that enhanced anticancer effect of an EE was mediated at least in part through modulation of T-cell immunity and provided support to the emerging concept of manipulating a single gene in the brain to improve cancer immunotherapy. Cancer Immunol Res; 4(6); 488-97. ©2016 AACR.