Dietary energy restriction modulates the activity of AMP-activated protein kinase, Akt, and mammalian target of rapamycin in mammary carcinomas, mammary gland, and liver

Hepatotoxic of polystyrene microplastics in aged mice: Focus on the role of gastrointestinal transformation and AMPK/FoxO pathway

Microplastic (MP) toxicity has attracted widespread attention, whereas before triggering hepatotoxicity, ingested MPs first undergo transportation and digestion processes in the gastrointestinal tract, possibly interacting with the gastrointestinal contents (GIC). More alarming is the need for more understanding of how this process may impact the liver health of aged animals. This study selected old mice. Firstly, we incubated polystyrene microplastics (PS-MPs, 1 μm) with GIC extract. The results of SEM/EDS indicated a structural alteration in PS-MPs. Additionally, impurities resembling corona, rich in heteroatoms (O, N, and S), were observed. This resulted in an enhanced aggregating phenomenon of MPs. We conducted a 10-day experiment exposing aged mice to four concentrations of PS-MPs, ranging from 1 × 103 to 1 × 1012 particles/L. Subsequent measurements of tissue pathology and body and organ weights were conducted, revealing alterations in liver structure. In the liver, 12 crucial metabolites were found by LC-MS technology, including purines, lipids, and amino acids. The AMPK/FoxO pathway was enriched, activated, and validated in western blotting results. We also comprehensively examined the innate immune system, inflammatory factors, and oxidative stress indicators. The results indicated decreased C3 levels, stable C4 levels, inflammatory factors (IL-6 and IL-8), and antioxidant enzymes were increased to varying degrees. PS-MPs also caused DNA oxidative damage. These toxic effects exhibited a specific dose dependence. Overall, after the formation of the gastrointestinal corona, PS-MPs subsequently impact various cellular processes, such as cycle arrest (p21), leading to hepatic and health crises in the elderly. The presence of gastrointestinal coronas also underscores the MPs' morphology and characteristics, which should be distinguished after ingestion.

High-fat diet and obesity are associated with differential angiogenic gene expression in epithelial ovarian cancer

OBJECTIVE

We sought to evaluate the association between diet and angiogenic biomarkers in KpB mice, and the association between these markers, body mass index (BMI), and overall survival (OS) in high-grade serous cancers (HGSC).

METHODS

Tumors previously obtained from KpB mice subjected to high-fat diets (HFD, n = 10) or low-fat diets (LFD, n = 10) were evaluated for angiogenesis based on CD-31 microvessel density (MVD). Data from prior microarray analysis (Agilent 244 K arrays) conducted in 10 mice were utilized to assess associations between diet and angiogenetic biomarkers. Agilent (mouse) and Affymetrix Human Genome U133a probes were linked to 162 angiogenic-related genes. The associations between biomarkers, BMI, and OS were evaluated in an HGSC internal database (IDB) (n = 40). Genes with unadjusted p < 0.05 were evaluated for association with OS in the TCGA-OV database (n = 339).

RESULTS

There was no association between CD-31 and diet in mice (p = 0.66). Sixteen angiogenic-related genes passed the p < 0.05 threshold for association with HFD vs. LFD. Transforming growth factor-alpha (TGFA) demonstrated 72% higher expression in HFD vs. LFD mice (p = 0.04). Similar to the mouse study, in our HGSC IDB, higher TGFA expression correlated with higher BMI (p = 0.01) and shorter survival (p = 0.001). In the TCGA-OV dataset, BMI data was not available and there was no association between TGFA and OS (p = 0.48).

CONCLUSIONS

HFD and obesity may promote tumor progression via differential modulation of TGFA. We were unable to confirm this finding in the TCGA dataset. Further evaluation of TGFA is needed to determine if this is a target unique to obesity-driven HGSC.

Phenotypic molecular features of long-lived animal species

One of the challenges facing science/biology today is uncovering the molecular bases that support and determine animal and human longevity. Nature, in offering a diversity of animal species that differ in longevity by more than 5 orders of magnitude, is the best 'experimental laboratory' to achieve this aim. Mammals, in particular, can differ by more than 200-fold in longevity. For this reason, most of the available evidence on this topic derives from comparative physiology studies. But why can human beings, for instance, reach 120 years whereas rats only last at best 4 years? How does nature change the longevity of species? Longevity is a species-specific feature resulting from an evolutionary process. Long-lived animal species, including humans, show adaptations at all levels of biological organization, from metabolites to genome, supported by signaling and regulatory networks. The structural and functional features that define a long-lived species may suggest that longevity is a programmed biological property.

Leucine and arginine enhance milk fat and milk protein synthesis via the CaSR/Gi/mTORC1 and CaSR/Gq/mTORC1 pathways

BACKGROUND AND AIMS

Amino acids (AAs) not only constitute milk protein but also stimulate milk synthesis through the activation of mTORC1 signaling, but which amino acids that have the greatest impact on milk fat and protein synthesis is still very limited. In this study, we aimed to identify the most critical AAs involved in the regulation of milk synthesis and clarify how these AAs regulate milk synthesis through the G-protein-coupled receptors (GPCRs) signaling pathway.

METHODS

In this study, a mouse mammary epithelial cell line (HC11) and porcine mammary epithelial cells (PMECs) were selected as study subjects. After treatment with different AAs, the amount of milk protein and milk fat synthesis were detected. Activation of mTORC1 and GPCRs signaling induced by AAs was also investigated.

RESULTS

In this study, we demonstrate that essential amino acids (EAAs) are crucial to promote lactation by increasing the expression of genes and proteins related to milk synthesis, such as ACACA, FABP4, DGAT1, SREBP1, α-casein, β-casein, and WAP in HC11 cells and PMECs. In addition to activating mTORC1, EAAs uniquely regulate the expression of calcium-sensing receptor (CaSR) among all amino-acid-responsive GPCRs, which indicates a potential link between CaSR and the mTORC1 pathway in mammary gland epithelial cells. Compared with other EAAs, leucine and arginine had the greatest capacity to trigger GPCRs (p-ERK) and mTORC1 (p-S6K1) signaling in HC11 cells. In addition, CaSR and its downstream G proteins Gi, Gq, and Gβγ are involved in the regulation of leucine- and arginine-induced milk synthesis and mTORC1 activation. Taken together, our data suggest that leucine and arginine can efficiently trigger milk synthesis through the CaSR/Gi/mTORC1 and CaSR/Gq/mTORC1 pathways.

CONCLUSION

We found that the G-protein-coupled receptor CaSR is an important amino acid sensor in mammary epithelial cells. Leucine and arginine promote milk synthesis partially through the CaSR/Gi/mTORC1 and CaSR/Gq/mTORC1 signaling systems in mammary gland epithelial cells. Although this mechanism needs further verification, it is foreseeable that this mechanism may provide new insights into the regulation of milk synthesis.

Thermo-Chemical Resistance to Combination Therapy of Glioma Depends on Cellular Energy Level

Thermal therapy has been widely used in clinical tumor treatment and more recently in combination with chemotherapy, where the key challenge is the treatment resistance. The mechanism at the cellular level underlying the resistance to thermo-chemical combination therapy remains elusive. In this study, we constructed 3D culture models for glioma cells (i.e., 3D glioma spheres) as the model system to recapitulate the native tumor microenvironment and systematically investigated the thermal response of 3D glioma spheres at different hyperthermic temperatures. We found that 3D glioma spheres show high viability under hyperthermia, especially under high hyperthermic temperatures (42 °C). Further study revealed that the main mechanism lies in the high energy level of cells in 3D glioma spheres under hyperthermia, which enables the cells to respond promptly to thermal stimulation and maintain cellular viability by upregulating the chaperon protein Hsp70 and the anti-apoptotic pathway AKT. Besides, we also demonstrated that 3D glioma spheres show strong drug resistance to the thermo-chemical combination therapy. This study provides a new perspective on understanding the thermal response of combination therapy for tumor treatment.

Metformin acts as a dual glucose regulator in mouse brain

Aims: Metformin improves glucose regulation through various mechanisms in the periphery. Our previous study revealed that oral intake of metformin activates several brain regions, including the hypothalamus, and directly activates hypothalamic S6 kinase in mice. In this study, we aimed to identify the direct effects of metformin on glucose regulation in the brain. Materials and methods: We investigated the role of metformin in peripheral glucose regulation by directly administering metformin intracerebroventricularly in mice. The effect of centrally administered metformin (central metformin) on peripheral glucose regulation was evaluated by oral or intraperitoneal glucose, insulin, and pyruvate tolerance tests. Hepatic gluconeogenesis and gastric emptying were assessed to elucidate the underlying mechanisms. Liver-specific and systemic sympathetic denervation were performed. Results: Central metformin improved the glycemic response to oral glucose load in mice compared to that in the control group, and worsened the response to intraperitoneal glucose load, indicating its dual role in peripheral glucose regulation. It lowered the ability of insulin to decrease serum glucose levels and worsened the glycemic response to pyruvate load relative to the control group. Furthermore, it increased the expression of hepatic G6pc and decreased the phosphorylation of STAT3, suggesting that central metformin increased hepatic glucose production. The effect was mediated by sympathetic nervous system activation. In contrast, it induced a significant delay in gastric emptying in mice, suggesting its potent role in suppressing intestinal glucose absorption. Conclusion: Central metformin improves glucose tolerance by delaying gastric emptying through the brain-gut axis, but at the same time worsens it by increasing hepatic glucose production via the brain-liver axis. However, with its ordinary intake, central metformin may effectively enhance its glucose-lowering effect through the brain-gut axis, which could surpass its effect on glucose regulation via the brain-liver axis.

Dietary restriction in senolysis and prevention and treatment of disease

Aging represents a key risk factor for a plethora of diseases. Targeting detrimental processes which occur during aging, especially before onset of age-related disease, could provide drastic improvements in healthspan. There is increasing evidence that dietary restriction (DR), including caloric restriction, fasting, or fasting-mimicking diets, extend both lifespan and healthspan. This has sparked interest in the use of dietary regimens as a non-pharmacological means to slow aging and prevent disease. Here, we review the current evidence on the molecular mechanisms underlying DR-induced health improvements, including removal of senescent cells, metabolic reprogramming, and epigenetic rejuvenation.

mTOR Complex 1 Content and Regulation Is Adapted to Animal Longevity

Decreased content and activity of the mechanistic target of rapamycin (mTOR) signalling pathway, as well as the mTOR complex 1 (mTORC1) itself, are key traits for animal species and human longevity. Since mTORC1 acts as a master regulator of intracellular metabolism, it is responsible, at least in part, for the longevous phenotype. Conversely, increased content and activity of mTOR signalling and mTORC1 are hallmarks of ageing. Additionally, constitutive and aberrant activity of mTORC1 is also found in age-related diseases such as Alzheimer’s disease (AD) and cancer. The downstream processes regulated through this network are diverse, and depend upon nutrient availability. Hence, multiple nutritional strategies capable of regulating mTORC1 activity and, consequently, delaying the ageing process and the development of age-related diseases, are under continuous study. Among these, the restriction of calories is still the most studied and robust intervention capable of downregulating mTOR signalling and feasible for application in the human population.

Energy deprivation-induced AMPK activation inhibits milk synthesis by targeting PrlR and PGC-1α

Background

The mammary gland is responsible for milk production and secretion, which is critical for neonatal health during lactation. Lactation efficiency is largely affected by energy status with unclear mechanism.

Results

In the current study, we found that synthesis of milk fat and protein was significantly inhibited under energy-deficient conditions, which is accompanied with AMP-activated protein kinase (AMPK) activation. Modulating the AMPK signaling pathway directly or indirectly affects the synthesis of milk fat and protein. Besides mammalian target of rapamycin complex 1 (mTORC1) signaling in the regulation of milk synthesis, we discovered that AMPK mainly regulates the synthesis of milk protein through prolactin signaling. Mechanistically, AMPK triggers the ubiquitination of prolactin receptor (PrlR) through regulating the activity of β-transducin repeat-containing protein (β-TrCP, an E3 ligase). Subsequently, PrlR is degraded by the endocytosis process of lysosomes, which further attenuates prolactin signaling. In addition, our results revealed that AMPK activation inhibits milk fat synthesis through decreasing and accelerating de novo synthesis and β-oxidation of fatty acids, respectively. To be precise, AMPK activation inhibits rate limiting enzymes and transcriptional regulatory factors involved in de novo fatty acid synthesis and decreases the acetylation process of peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α) to strengthen the oxidation of fatty acids.

Conclusions

Taken together, AMPK regulates the synthesis of milk not only depends on canonical mTORC1 signaling and key rate-limiting enzymes, but also through manipulating the degradation of PrlR and the acetylation of PGC-1α.

Adipose Stromal/Stem Cell-Derived Extracellular Vesicles: Potential Next-Generation Anti-Obesity Agents

Over the last decade, several compounds have been identified for the treatment of obesity. However, due to the complexity of the disease, many pharmacological interventions have raised concerns about their efficacy and safety. Therefore, it is important to discover new factors involved in the induction/progression of obesity. Adipose stromal/stem cells (ASCs), which are mostly isolated from subcutaneous adipose tissue, are the primary cells contributing to the expansion of fat mass. Like other cells, ASCs release nanoparticles known as extracellular vesicles (EVs), which are being actively studied for their potential applications in a variety of diseases. Here, we focused on the importance of the contribution of ASC-derived EVs in the regulation of metabolic processes. In addition, we outlined the advantages/disadvantages of the use of EVs as potential next-generation anti-obesity agents.

Intermittent and Periodic Fasting, Hormones, and Cancer Prevention

The restriction of proteins, amino acids or sugars can have profound effects on the levels of hormones and factors including growth hormone, IGF-1 and insulin. In turn, these can regulate intracellular signaling pathways as well as cellular damage and aging, but also multisystem regeneration. Both intermittent (IF) and periodic fasting (PF) have been shown to have both acute and long-term effects on these hormones. Here, we review the effects of nutrients and fasting on hormones and genes established to affect aging and cancer. We describe the link between dietary interventions and genetic pathways affecting the levels of these hormones and focus on the mechanisms responsible for the cancer preventive effects. We propose that IF and PF can reduce tumor incidence both by delaying aging and preventing DNA damage and immunosenescence and also by killing damaged, pre-cancerous and cancer cells.

Designing Relevant Preclinical Rodent Models for Studying Links Between Nutrition, Obesity, Metabolism, and Cancer

Diet and nutrition are intricately related to cancer prevention, growth, and treatment response. Preclinical rodent models are a cornerstone to biomedical research and remain instrumental in our understanding of the relationship between cancer and diet and in the development of effective therapeutics. However, the success rate of translating promising findings from the bench to the bedside is suboptimal. Well-designed rodent models will be crucial to improving the impact basic science has on clinical treatment options. This review discusses essential experimental factors to consider when designing a preclinical cancer model with an emphasis on incorporating these models into studies interrogating diet, nutrition, and metabolism. The aims of this review are to (a) provide insight into relevant considerations when designing cancer models for obesity, nutrition, and metabolism research; (b) identify common pitfalls when selecting a rodent model; and (c) discuss strengths and limitations of available preclinical models. Expected final online publication date for the Annual Review of Nutrition, Volume 41 is September 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Obesity and aging: Molecular mechanisms and therapeutic approaches

The epidemic of obesity is a major challenge for health policymakers due to its far-reaching effects on population health and potentially overwhelming financial burden on healthcare systems. Obesity is associated with an increased risk of developing acute and chronic diseases, including hypertension, stroke, myocardial infarction, cardiovascular disease, diabetes, and cancer. Interestingly, the metabolic dysregulation associated with obesity is similar to that observed in normal aging, and substantial evidence suggests the potential of obesity to accelerate aging. Therefore, understanding the mechanism of fat tissue dysfunction in obesity could provide insights into the processes that contribute to the metabolic dysfunction associated with the aging process. Here, we review the molecular and cellular mechanisms underlying both obesity and aging, and how obesity and aging can predispose individuals to chronic health complications. The potential of lifestyle and pharmacological interventions to counter obesity and obesity-related pathologies, as well as aging, is also addressed.

Nutritional Regulation of Mammary Gland Development and Milk Synthesis in Animal Models and Dairy Species

In mammals, milk is essential for the growth, development, and health. Milk quantity and quality are dependent on mammary development, strongly influenced by nutrition. This review provides an overview of the data on nutritional regulations of mammary development and gene expression involved in milk component synthesis. Mammary development is described related to rodents, rabbits, and pigs, common models in mammary biology. Molecular mechanisms of the nutritional regulation of milk synthesis are reported in ruminants regarding the importance of ruminant milk in human health. The effects of dietary quantitative and qualitative alterations are described considering the dietary composition and in regard to the periods of nutritional susceptibly. During lactation, the effects of lipid supplementation and feed restriction or deprivation are discussed regarding gene expression involved in milk biosynthesis, in ruminants. Moreover, nutrigenomic studies underline the role of the mammary structure and the potential influence of microRNAs. Knowledge from three lactating and three dairy livestock species contribute to understanding the variety of phenotypes reported in this review and highlight (1) the importance of critical physiological stages, such as puberty gestation and early lactation and (2) the relative importance of the various nutrients besides the total energetic value and their interaction.

Physical Activity and Liver Cancer Risk: A Systematic Review and Meta-analyses

OBJECTIVE

Liver cancer is the second most common cause of death from cancer. Physical activity (PA) was found to be associated with lower risks of several types of cancer. However, the association between PA and the risk of liver cancer is still inconclusive. This systematic review and meta-analysis was aiming to summarize the association between PA and liver cancer risk.

METHODS

Literatures related were identified by searching PubMed, EMBASE, and Chinese Biomedical literature database from 1965 to 2017 without language limitation. Meta-analyses were performed using random effect model.

RESULTS

A total of 5 cohort studies involving 2 513 975 subjects were identified. The pooled relative risk of leisure-time PA with liver cancer risk was 0.92 [95% confidence interval (CI), 0.84-1.01]. There is no significant association between leisure-time PA and liver cancer risk. However, leisure-time PA significantly reduced liver cancer risk in never smokers. The pooled hazard ratio of daily total PA with liver cancer risk was 0.75 (95% CI, 0.66-0.86).

CONCLUSIONS

Daily total PA significantly reduces liver cancer risk, whereas leisure-time PA significantly reduces liver cancer risk only in never smokers.

Direct or indirect regulation of muscle protein synthesis by energy status?

Muscle protein synthesis (MPS) is a complex and finely-regulated mechanism that plays a key role in muscle homeostasis. Amino acid bioavailability is widely considered a major driver of MPS regulation via mTOR pathway activation. However, recent results suggest that amino acid bioavailability affects cellular energy status. Whatever the tool used to modulate energy status (amino acid depletion or mild mitochondrial uncoupling), a decrease in cellular energy status decreases MPS, without necessarily involving the mTOR pathway. Here we propose that energy status directly regulates one or several energy-consuming step(s) during MPS. This new paradigm modifies our vision of protein metabolism and raises prospects for new advances in therapeutics.

Current Evidences and Future Perspectives for AMPK in the Regulation of Milk Production and Mammary Gland Biology

Activated protein kinase (AMP)-activated protein kinase (AMPK) senses the cellular energy status and coordinates catabolic and anabolic processes. Extensive studies have proposed that AMPK regulates energy homeostasis, cell growth, autophagy, mitochondrial biology and inflammation. The biological functions of AMPK vary in different tissues or organs. As a unique organ that produces milk, the mammary gland has recently attracted substantial research attention. This review discusses how AMPK in the mammary gland is activated by energy deprivation and heat stress via the activation of canonical and non-canonical pathways. In addition, the important downstream targets of AMPK and their functions in the mammary gland, especially during milk synthesis, are summarized in the review.

AMPKα2 deficiency exacerbates hypoxia-induced pulmonary hypertension by promoting pulmonary arterial smooth muscle cell proliferation

Increased evidence indicates that adenosine monophosphate-activated protein kinase (AMPK) plays a vital role in vascular homeostasis, especially under hypoxia, and protects against the progression of pulmonary hypertension (PH). However, the role of AMPK in the pathogenesis of PH remains to be clarified. In the present study, we confirmed that a loss of AMPKα2 exacerbated the development of PH by using hypoxia-induced PH model in AMPKα2 ^-/- mice. After a 4-week period of hypoxic exposure, AMPKα2 ^-/- mice exhibited more severe pulmonary vascular remodeling and pulmonary vascular smooth muscle cell (SMC) proliferation when compared with wild type (WT) mice. In vitro, AMPKα2 knockdown promoted the proliferation of pulmonary arterial smooth muscle cells (PASMCs) under hypoxia. This phenomenon was accompanied by upregulated Skp2 and downregulated p27^kip1 expression and was abolished by rapamycin, an inhibitor of mTOR. These results indicate that AMPKα2 deficiency exacerbates hypoxia-induced PH by promoting PASMC proliferation via the mTOR/Skp2/p27^kip1 signaling axis. Therefore, enhanced AMPKα2 activity might underlie a novel therapeutic strategy for the management of PH.

The Role of Diet in Cancer Prevention and Chemotherapy Efficacy

Despite great advances in treatment, cancer remains a leading cause of death worldwide. Diet can greatly impact health, while caloric restriction and fasting have putative benefits for disease prevention and longevity. Strong epidemiological associations exist between obesity and cancer, whereas healthy diets can reduce cancer risk. However, less is known about how diet might impact cancer once it has been diagnosed and particularly how diet can impact cancer treatment. In the present review, we discuss the links between obesity, diet, and cancer. We explore potential mechanisms by which diet can improve cancer outcomes, including through hormonal, metabolic, and immune/inflammatory effects, and present the limited clinical research that has been published in this arena. Though data are sparse, diet intervention may reduce toxicity, improve chemotherapy efficacy, and lower the risk of long-term complications in cancer patients. Thus, it is important that we understand and expand the science of this important but complex adjunctive cancer treatment strategy.

How Inflammation Blunts Innate Immunity in Aging

The collective loss of immune protection during aging leads to poor vaccine responses and an increased severity of infection for the elderly. Here, we review our current understanding of effects of aging on the cellular and molecular dysregulation of innate immune cells as well as the relevant tissue milieu which influences their functions. The innate immune system is composed of multiple cell types which provide distinct and essential roles in tissue surveillance and antigen presentation as well as early responses to infection or injury. Functional defects that arise during aging lead to a reduced dynamic range of responsiveness, altered cytokine dynamics, and impaired tissue repair. Heightened inflammation influences both the dysregulation of innate immune responses as well as surrounding tissue microenvironments which have a critical role in development of a functional immune response. In particular, age-related physical and inflammatory changes in the skin, lung, lymph nodes, and adipose tissue reflect disrupted architecture and spatial organization contributing to diminished immune responsiveness. Underlying mechanisms include altered transcriptional programming and dysregulation of critical innate immune signaling cascades. Further, we identify signaling functions of bioactive lipid mediators which address chronic inflammation and may contribute to the resolution of inflammation to improve innate immunity during aging.

The Metabolic Landscape of Lung Cancer: New Insights in a Disturbed Glucose Metabolism

Metabolism encompasses the biochemical processes that allow healthy cells to keep energy, redox balance and building blocks required for cell development, survival, and proliferation steady. Malignant cells are well-documented to reprogram their metabolism and energy production networks to support rapid proliferation and survival in harsh conditions via mutations in oncogenes and inactivation of tumor suppressor genes. Despite the histologic and genetic heterogeneity of tumors, a common set of metabolic pathways sustain the high proliferation rates observed in cancer cells. This review with a focus on lung cancer covers several fundamental principles of the disturbed glucose metabolism, such as the “Warburg” effect, the importance of the glycolysis and its branching pathways, the unanticipated gluconeogenesis and mitochondrial metabolism. Furthermore, we highlight our current understanding of the disturbed glucose metabolism and how this might result in the development of new treatments.

Effects of short-term fasting on cancer treatment

Growing preclinical evidence shows that short-term fasting (STF) protects from toxicity while enhancing the efficacy of a variety of chemotherapeutic agents in the treatment of various tumour types. STF reinforces stress resistance of healthy cells, while tumor cells become even more sensitive to toxins, perhaps through shortage of nutrients to satisfy their needs in the context of high proliferation rates and/or loss of flexibility to respond to extreme circumstances. In humans, STF may be a feasible approach to enhance the efficacy and tolerability of chemotherapy. Clinical research evaluating the potential of STF is in its infancy. This review focuses on the molecular background, current knowledge and clinical trials evaluating the effects of STF in cancer treatment. Preliminary data show that STF is safe, but challenging in cancer patients receiving chemotherapy. Ongoing clinical trials need to unravel if STF can also diminish toxicity and increase efficacy of chemotherapeutic regimes in daily practice.

Metabolic Regulation of Dendritic Cell Differentiation

Dendritic cells (DCs) are important antigen-presenting cells (APCs) that play essential roles in bridging innate and adaptive immune responses. Differentiation stages of DC subsets from bone marrow progenitor cells have been well-defined during the past decades. Features that distinguish DC progenitor cells from each differentiation stages, related signaling pathways and transcription factors that are crucial for DC lineage commitment have been well-elucidated in numerous studies. Recently, growing evidence are showing that cellular metabolism, as one of the most fundamental process of cells, has essential role in the modulation of immune system. There have been multiple reports and reviews that focus on the metabolic modulations on DC functions, however little attention had been paid to the metabolic regulation of DC development and differentiation. In recent years, increasing evidence suggests that metabolic regulations also exert significant impact on DC differentiation, as well as on the homeostasis of tissue resident DCs. The focus of this review is to summarize the findings from recent studies on the metabolic regulation of DC differentiation and to discuss the impacts of the three major aspects of metabolism on the processes of DC development and differentiation, namely the changes in metabolic pathways, the molecular signaling pathways that modulate cell metabolism, and the effects of metabolites and nutrients. The aim of this review is to draw attentions to this important and exciting research field where the effects of metabolic process and their regulation in DC differentiation need to be further explored.

Metformin and glucose starvation decrease the migratory ability of hepatocellular carcinoma cells: targeting AMPK activation to control migration

Hepatocellular carcinoma (HCC) is a highly metastatic cancer with very poor prognosis. AMP activated kinase (AMPK) constitutes a candidate to inhibit HCC progression. First, AMPK is downregulated in HCC. Second, glucose starvation induces apoptosis in HCC cells via AMPK. Correspondingly, metformin activates AMPK and inhibits HCC cell proliferation. Nevertheless, the effect of AMPK activation on HCC cell invasiveness remains elusive. Here, migration/invasion was studied in HCC cells exposed to metformin and glucose starvation. Cell viability, proliferation and differentiation, as well as AMPK and PKA activation were analyzed. In addition, invasiveness in mutants of the AMPKα activation loop was assessed. Metformin decreased cell migration, invasion and epithelial-mesenchymal transition, and interference with AMPKα expression avoided metformin actions. Those antitumor effects were potentiated by glucose deprivation. Metformin activated AMPK at the same time that inhibited PKA, and both effects were enhanced by glucose starvation. Given that AMPKα(S173) phosphorylation by PKA decreases AMPK activation, we hypothesized that the reduction of PKA inhibitory effect by metformin could explain the increased antitumor effects observed. Supporting this, in AMPK activating conditions, cell migration/invasion was further impaired in AMPKα(S173C) mutant cells. Metformin emerges as a strong inhibitor of migration/invasion in HCC cells, and glucose restriction potentiates this effect.

Metformin triggers the intrinsic apoptotic response in human AGS gastric adenocarcinoma cells by activating AMPK and suppressing mTOR/AKT signaling

Metformin is commonly used to treat patients with type 2 diabetes and is associated with a decreased risk of cancer. Previous studies have demonstrated that metformin can act alone or in synergy with certain anticancer agents to achieve anti-neoplastic effects on various types of tumors via adenosine monophosphate-activated protein kinase (AMPK) signaling. However, the role of metformin in AMPK-mediated apoptosis of human gastric cancer cells is poorly understood. In the current study, metformin exhibited a potent anti-proliferative effect and induced apoptotic characteristics in human AGS gastric adenocarcinoma cells, as demonstrated by MTT assay, morphological observation method, terminal deoxynucleotidyl transferase dUTP nick end labeling and caspase-3/7 assay kits. Western blot analysis demonstrated that treatment with metformin increased the phosphorylation of AMPK, and decreased the phosphorylation of AKT, mTOR and p70S6k. Compound C (an AMPK inhibitor) suppressed AMPK phosphorylation and significantly abrogated the effects of metformin on AGS cell viability. Metformin also reduced the phosphorylation of mitogen-activated protein kinases (ERK, JNK and p38). Additionally, metformin significantly increased the cellular ROS level and included loss of mitochondrial membrane potential (ΔΨm). Metformin altered apoptosis-associated signaling to downregulate the BAD phosphorylation and Bcl-2, pro-caspase-9, pro-caspase-3 and pro-caspase-7 expression, and to upregulate BAD, cytochrome c, and Apaf-1 proteins levels in AGS cells. Furthermore, z-VAD-fmk (a pan-caspase inhibitor) was used to assess mitochondria-mediated caspase-dependent apoptosis in metformin-treated AGS cells. The findings demonstrated that metformin induced AMPK-mediated apoptosis, making it appealing for development as a novel anticancer drug for the treating gastric cancer.

Pas Kinase Deficiency Triggers Antioxidant Mechanisms in the Liver

Metabolic dysfunction in the liver is the cause of numerous pathologies, which are associated with an altered redox state. PASK (PAS Domain Kinase) is a nutrient and bioenergetic sensor. We contend that PASK could act as an oxidative stress sensor in liver and/or control the metabolic balance, playing a role in the mitochondrial homeostasis. Using PASK-deficient mice, we observed that PASK deficiency promotes antioxidant response mechanisms: a lower production of ROS/RNS under non-fasting conditions, overexpression of genes coding to ROS-detoxifying enzymes and mitochondrial fusion proteins (MnSod Gpx, Mfn1 and Opa1), coactivator Ppargc1a, transcription factors (Pparg and FoxO3a) and deacetylase Sirt1. Also, under fasting conditions, PASK deficiency induced the overexpression of Ppargc1a, Ppara, Pparg, FoxO3a and Nrf2 leading to the overexpression of genes coding to antioxidant enzymes such as MnSOD, Cu/ZnSOD, GPx, HO1 and GCLm. Additionally, inducing PINK1 involved in cell survival and mitophagy. These changes kept ROS steady levels and improved the regenerative state. We suggest a new role for PASK as a controller of oxidative stress and mitochondrial dynamics in the liver. In fact, antioxidant response is PASK dependent. PASK-targeting could therefore be a good way of reducing the oxidative stress in order to prevent or treat liver diseases.

Caloric Restriction Dramatically Stalls Lesion Growth in Mice With Induced Endometriosis

Caloric restriction (CR) has been demonstrated to have many health-beneficial effects in many species, but whether CR can impede the development of endometriosis is unknown. To test the hypothesis that CR can impede the growth of endometriotic lesions and fibrogenesis, we conducted 2 experiments. In experiment 1, 20 female Balb/C mice were randomly assigned to either ad libitum (AL) group that was fed AL or to CR group that was fed 30% less calories than that of AL mice. Two weeks after the implementation of the dietary intervention, endometriosis was induced by intraperitoneal injection of endometrial fragments. Two weeks after the induction, all mice were sacrificed and their lesion samples were evaluated. In experiment 2, another 20 mice were used and CR was implemented 2 weeks after induction of endometriosis and lasted for 4 weeks. Caloric restriction instituted before the induction of endometriosis reduced the lesion weight by 88.5%, whereas CR implemented well after lesions were established reduced the lesion weight by 93.0%. In both cases, CR significantly increased staining levels of markers of autophagy but reduced proliferation, angiogenesis, steroidogenesis, and fibrosis in lesions as compared with the AL group. Consequently, CR, instituted either before or after the induction of endometriosis, dramatically curbs the growth of endometriotic lesions and fibrogenesis through multiple mechanisms. Caloric restriction and CR mimetics, a family of compounds mimicking the beneficial effect of CR, even when instituted well after lesions are established, may stall the development of endometriosis. Given the scarcity in research on how lifestyle can impact on the development of endometriosis, our study should hopefully stimulate more research in this area.

Phenylalanine regulates initiation of digestive enzyme mRNA translation in pancreatic acinar cells and tissue segments in dairy calves

As new nutritional strategies for ruminant are designed to change production efficiency by improving the supply of rumen protect protein, lipid, and even starch, the digestive system must fit to utilize these increased nutrient supplies, especially the pancreas. The objective of this study was to investigate the effects of phenylalanine (Phe) on digestive enzymes synthesis or secretion and cellular signaling in pancreatic acinar (PA) cells of dairy calves. The PA cells isolated from fresh pancreas of dairy calves, and cultured in completed RIPA 1640 medium with no fetal serum but 0, 0.15 and 0.45 mM Phe at 37°C in CO₂ incubator for 120 min. The pancreatic tissue segments (PTS) was cut approximately 2 × 2 mm from the fresh pancreas, and incubated in oxygenated Krebs-Ringer bicarbonate (KRB) buffer containing 0 or 0.35 mM Phe at 39°C for 180 min, and the samples were collected every 60 min after incubation. In PA cells, Phe increased (P < 0.05) the α-amylase secretion and mRNA expression, the phosphorylation of ribosomal protein S6 kinase 1 (S6K1) and eukaryotic initiation factor 4E binding protein 1 (4EBP1). In PTS, the Phe increased (P < 0.05) α-amylase and trypsin synthesis, secretion and mRNA expression, as well as the phosphorylation of S6K1 and 4EBP1. Conclusively, these results suggested that Phe regulates the synthesis or secretion of α-amylase, trypsin and lipase through mRNA translation initiation factors – S6K1 and 4EBP1.

Fructose Feeding during the Postabsorptive State Alters Body Composition and Spares Nitrogen in Protein-Energy-Restricted Old Rats

Background

Fructose feeding in the context of high energy intake is recognized as being responsible for metabolic dysregulation. However, its consumption in the postabsorptive state might contribute to reducing the use of amino acids (AAs) as energy substrates and thus spare nitrogen resources, which could be beneficial during catabolic states.

Objective

We hypothesized that fructose feeding during a catabolic situation corresponding to protein-energy restriction (PER) in older rats would reduce AA utilization for energy purposes, thus slowing down the loss of body weight (BW) and improving body composition.

Methods

For 45 d, 22-mo-old male Wistar rats (average weight: 716 g) were fed a control ration (13% protein) either at normal (20 g/d), restricted (PER: 10 g/d), or at PER levels supplemented with glucose (3 g/d) or fructose (3 g/d) and then studied in the postabsorptive state. We measured BW, body composition, and enzyme activities and metabolite concentrations related to glucose, fructose, and AA metabolism.

Results

Both glucose and fructose feeding reduced PER-induced loss of BW and lean mass (-27% compared with PER), but only fructose reduced the loss of fat mass (-28% compared with PER). Fructose feeding prevented the PER-induced loss of muscle and intestinal mass. Fructose feeding also reduced circulating branched-chain AA concentrations by 50% (compared with PER) and increased those of alanine (+65% compared with PER). A reduction in hepatic enzymes related to AA catabolism was also observed during fructose feeding (compared with PER), whereas glycogen concentrations were enhanced in both intestine (+300%) and muscle (+21%).

Conclusions

We showed that in PER older rats, fructose feeding improved body composition and the weight of several organs by reducing AA catabolism and utilization for energy production and liver autophagy potential. This could be advantageous in sparing body proteins, particularly during catabolic states, such as those related to malnutrition during aging.

Docosahexaenoic Acid in Combination with Dietary Energy Restriction for Reducing the Risk of Obesity Related Breast Cancer

There is strong evidence that obesity poses a significant risk factor for postmenopausal breast cancer. There are multiple mechanisms by which obesity can predispose to breast cancer, prominent among which is the creation of a pro-inflammatory milieu systemically in the visceral and subcutaneous tissue, as well as locally in the breast. Although dietary intervention studies have shown in general a favorable effect on biomarkers of breast cancer risk, it is still unclear whether losing excess weight will lower the risk. In this manuscript, we will review the evidence that omega-3 fatty acids, and among them docosahexaenoic acid (DHA) in particular, may reduce the risk of obesity related breast cancer primarily because of their pleotropic effects which target many of the systemic and local oncogenic pathways activated by excess weight. We will also review the evidence indicating that intentional weight loss (IWL) induced by dietary energy restriction (DER) will augment the tumor protective effect of DHA because of its complementary mechanisms of action and its ability to reverse the obesity-induced alterations in fatty acid metabolism predisposing to carcinogenesis. We believe that the combination of DER and DHA is a promising safe and effective intervention for reducing obesity-related breast cancer risk which needs to be validated in appropriately designed prospective, randomized clinical trials.

AMP-activated protein kinase and energy balance in breast cancer

Cancer growth and metastasis depends on the availability of energy. Energy-sensing systems are critical in maintaining a balance between the energy supply and utilization of energy for tumor growth. A central regulator in this process is AMP-activated protein kinase (AMPK). In times of energy deficit, AMPK is allosterically modified by the binding of increased levels of AMP and ADP, making it a target of specific AMPK kinases (AMPKKs). AMPK signaling prompts cells to produce energy at the expense of growth and motility, opposing the actions of insulin and growth factors. Increasing AMPK activity may thus prevent the proliferation and metastasis of tumor cells. Activated AMPK also suppresses aromatase, which lowers estrogen formation and prevents breast cancer growth. Biguanides can be used to activate AMPK, but AMPK activity is modified by many different interacting factors; understanding these factors is important in order to control the abnormal growth processes that lead to breast cancer neoplasia. Fatty acids, estrogens, androgens, adipokines, and another energy sensor, sirtuin-1, alter the phosphorylation and activation of AMPK. Isoforms of AMPK differ among tissues and may serve specific functions. Targeting AMPK regulatory processes at points other than the upstream AMPKKs may provide additional approaches for prevention of breast cancer neoplasia, growth, and metastasis.

Stearoyl-CoA desaturase-1, a novel target of omega-3 fatty acids for reducing breast cancer risk in obese postmenopausal women

BACKGROUND/OBJECTIVES

Conversion of saturated fatty acids to monounsaturated fatty acids by the enzyme stearoyl-Co-A-desaturase (SCD-1) is emerging as a major factor in promoting carcinogenesis including breast cancer. The aim of our study was to explore the regulation of SCD-1 by Raloxifene and omega-3 fatty acids in women at increased risk of breast cancer based on high breast density.

SUBJECTS/METHODS

As a reflection of SCD-1 activity, we measured the ratios of palmitoleic acid (C16:1n7) to palmitic acid (C16:0) (SCD-16) and oleic acid (C18:1n9) to steric acid (C18:0) (SCD-18) in plasma samples of postmenopausal women enrolled in our clinical trial (NCT00723398) designed to test the effects of the antiestrogen, Raloxifene and/or the omega-3 preparation Lovaza, on breast density, a validated biomarker of breast cancer risk.

RESULTS

We report that Lovaza but not Raloxifene-reduced SCD-16 and SCD-18 for the 2-year duration of the trial. Importantly, decreasing levels of SCD-16 and SCD-18 were associated with a progressive reduction in breast density but only in obese women (body mass index ⩾30).

CONCLUSIONS

Body mass index-related factors play an important role in the reduction of breast density and hence breast cancer risk by omega-3 fatty acids. SCD-1 may be a useful biomarker in future clinical trials testing the benefit of nutritional interventions in reducing obesity-associated breast cancer risk.

Circadian Rhythms in Diet-Induced Obesity

The biological clocks of the circadian timing system coordinate cellular and physiological processes and synchronizes these with daily cycles, feeding patterns also regulates circadian clocks. The clock genes and adipocytokines show circadian rhythmicity. Dysfunction of these genes are involved in the alteration of these adipokines during the development of obesity. Food availability promotes the stimuli associated with food intake which is a circadian oscillator outside of the suprachiasmatic nucleus (SCN). Its circadian rhythm is arranged with the predictable daily mealtimes. Food anticipatory activity is mediated by a self-sustained circadian timing and its principal component is food entrained oscillator. However, the hypothalamus has a crucial role in the regulation of energy balance rather than food intake. Fatty acids or their metabolites can modulate neuronal activity by brain nutrient-sensing neurons involved in the regulation of energy and glucose homeostasis. The timing of three-meal schedules indicates close association with the plasma levels of insulin and preceding food availability. Desynchronization between the central and peripheral clocks by altered timing of food intake and diet composition can lead to uncoupling of peripheral clocks from the central pacemaker and to the development of metabolic disorders. Metabolic dysfunction is associated with circadian disturbances at both central and peripheral levels and, eventual disruption of circadian clock functioning can lead to obesity. While CLOCK expression levels are increased with high fat diet-induced obesity, peroxisome proliferator-activated receptor (PPAR) alpha increases the transcriptional level of brain and muscle ARNT-like 1 (BMAL1) in obese subjects. Consequently, disruption of clock genes results in dyslipidemia, insulin resistance and obesity. Modifying the time of feeding alone can greatly affect body weight. Changes in the circadian clock are associated with temporal alterations in feeding behavior and increased weight gain. Thus, shift work is associated with increased risk for obesity, diabetes and cardio-vascular diseases as a result of unusual eating time and disruption of circadian rhythm.

The pentacyclic triterpenoid, plectranthoic acid, a novel activator of AMPK induces apoptotic death in prostate cancer cells

Epidemiologic studies indicated that diabetics treated with metformin had a lower incidence of cancer than those taking other anti-diabetes drugs. This led to a surge in the efforts for identification of safer and more effective metformin mimetic compounds. The plant Ficus microcarpa is widely used for the treatment of type 2 diabetes in traditional medicine in South Asia. We obtained extracts from this plant and identified a small molecule, plectranthoic acid (PA), with potent 5′AMP-activated kinase (AMPK) activating properties far superior than metformin. AMPK is the central hub of metabolic regulation and a well-studied therapeutic target for metabolic syndrome, type-2 diabetes and cancer. We observed that treatment of prostate cancer (PCa) cells with PA inhibited proliferation and induced G0/G1 phase cell cycle arrest that was associated with up-regulation of cyclin kinase inhibitors p21/CIP1 and p27/KIP1. PA treatment suppressed mTOR/S6K signaling and induced apoptosis in PCa cells in an AMPK-dependent manner. Interestingly, PA-induced autophagy in PCa cells was found to be independent of AMPK activation. Combination studies of PA and metformin demonstrated that metformin had an inhibitory effect on PA-induced AMPK activation and suppressed PA-mediated apoptosis. Given the anti-proliferative role of PA in cancer and its potent anti-hyperglycemic activity, we suggest that PA should be explored further as a novel activator of AMPK for its ultimate use for the prevention of cancers and treatment of type 2 diabetes.

Starving cancer from the outside and inside: separate and combined effects of calorie restriction and autophagy inhibition on Ras-driven tumors

Background

Calorie restriction (CR) prevents obesity and exerts anticancer effects in many preclinical models. CR is also increasingly being used in cancer patients as a sensitizing strategy prior to chemotherapy regimens. While the beneficial effects of CR are widely accepted, the mechanisms through which CR affects tumor growth are incompletely understood. In many cell types, CR and other nutrient stressors can induce autophagy, which provides energy and metabolic substrates critical for cancer cell survival. We hypothesized that limiting extracellular and intracellular substrate availability by combining CR with autophagy inhibition would reduce tumor growth more effectively than either treatment alone.

Results

A 30 % CR diet, relative to control diet, in nude mice resulted in significant decreases in body fat, blood glucose, and serum insulin, insulin-like growth factor-1, and leptin levels concurrent with increased adiponectin levels. In a xenograft model in nude mice involving H-Ras^G12V-transformed immortal baby mouse kidney epithelial cells with (Atg5^+/+) and without (Atg5^−/−) autophagic capacity, the CR diet (relative to control diet) genetically induced autophagy inhibition and their combination, each reduced tumor development and growth. Final tumor volume was greatest for Atg5^+/+ tumors in control-fed mice, intermediate for Atg5^+/+ tumors in CR-fed mice and Atg5^−/− tumors in control-fed mice, and lowest for Atg5^−/− tumors in CR mice. In Atg5^+/+ tumors, autophagic flux was increased in CR-fed relative to control-fed mice, suggesting that the prosurvival effects of autophagy induction may mitigate the tumor suppressive effects of CR. Metabolomic analyses of CR-fed, relative to control-fed, nude mice showed significant decreases in circulating glucose and amino acids and significant increases in ketones, indicating CR induced negative energy balance. Combining glucose deprivation with autophagy deficiency in Atg5^−/− cells resulted in significantly reduced in vitro colony formation relative to glucose deprivation or autophagy deficiency alone.

Conclusions

Combined restriction of extracellular (via CR in vivo or glucose deprivation in vitro) and intracellular (via autophagy inhibition) sources of energy and nutrients suppresses Ras-driven tumor growth more effectively than either CR or autophagy deficiency alone. Interventions targeting both systemic energy balance and tumor-cell intrinsic autophagy may represent a novel and effective anticancer strategy.

Effect of dietary fat and the circadian clock on the expression of brain-derived neurotrophic factor (BDNF)

Brain-derived neurotrophic factor (BDNF) is the most abundant neurotrophin in the brain and its decreased levels are associated with the development of obesity and neurodegeneration. Our aim was to test the effect of dietary fat, its timing and the circadian clock on the expression of BDNF and associated signaling pathways in mouse brain and liver. Bdnf mRNA oscillated robustly in brain and liver, but with a 12-h shift between the tissues. Brain and liver Bdnf mRNA showed a 12-h phase shift when fed ketogenic diet (KD) compared with high-fat diet (HFD) or low-fat diet (LFD). Brain or liver Bdnf mRNA did not show the typical phase advance usually seen under time-restricted feeding (RF). Clock knockdown in HT-4 hippocampal neurons led to 86% up-regulation of Bdnf mRNA, whereas it led to 60% down-regulation in AML-12 hepatocytes. Dietary fat in mice or cultured hepatocytes and hippocampal neurons led to increased Bdnf mRNA expression. At the protein level, HFD increased the ratio of the mature BDNF protein (mBDNF) to its precursor (proBDNF). In the liver, RF under LFD or HFD reduced the mBDNF/proBDNF ratio. In the brain, the two signaling pathways related to BDNF, mTOR and AMPK, showed reduced and increased levels, respectively, under timed HFD. In the liver, the reverse was achieved. In summary, Bdnf expression is mediated by the circadian clock and dietary fat. Although RF does not affect its expression phase, in the brain, when combined with high-fat diet, it leads to a unique metabolic state in which AMPK is activated, mTOR is down-regulated and the levels of mBDNF are high.

Anti-Tumor Effects of Ketogenic Diets in Mice: A Meta-Analysis

Background

Currently ketogenic diets (KDs) are hyped as an anti-tumor intervention aimed at exploiting the metabolic abnormalities of cancer cells. However, while data in humans is sparse, translation of murine tumor models to the clinic is further hampered by small sample sizes, heterogeneous settings and mixed results concerning tumor growth retardation. The aim was therefore to synthesize the evidence for a growth inhibiting effect of KDs when used as a monotherapy in mice.

Methods

We conducted a Bayesian random effects meta-analysis on all studies assessing the survival (defined as the time to reach a pre-defined endpoint such as tumor volume) of mice on an unrestricted KD compared to a high carbohydrate standard diet (SD). For 12 studies meeting the inclusion criteria either a mean survival time ratio (MR) or hazard ratio (HR) between the KD and SD groups could be obtained. The posterior estimates for the MR and HR averaged over four priors on the between-study heterogeneity τ² were MR = 0.85 (95% highest posterior density interval (HPDI) = [0.73, 0.97]) and HR = 0.55 (95% HPDI = [0.26, 0.87]), indicating a significant overall benefit of the KD in terms of prolonged mean survival times and reduced hazard rate. All studies that used a brain tumor model also chose a late starting point for the KD (at least one day after tumor initiation) which accounted for 26% of the heterogeneity. In this subgroup the KD was less effective (MR = 0.89, 95% HPDI = [0.76, 1.04]).

Conclusions

There was an overall tumor growth delaying effect of unrestricted KDs in mice. Future experiments should aim at differentiating the effects of KD timing versus tumor location, since external evidence is currently consistent with an influence of both of these factors.

Thiamin deficiency induces impaired fish gill immune responses, tight junction protein expression and antioxidant capacity: Roles of the NF-κB, TOR, p38 MAPK and Nrf2 signaling molecules

In this study, we investigate the effects of dietary thiamin deficiency on immune responses, tight junctions, antioxidant capacity and related signaling molecules in the gills of young grass carp (Ctenopharyngodon idella). Fish were fed diets that contained 0.12-2.04 mg thiamin kg(-1) for 8 weeks. We found that dietary thiamin deficiency resulted in reduced complement 3 content, lysozyme and acid phosphatase activities, mRNA levels of hepcidin, liver-expressed antimicrobial peptides 2, transforming growth factor (TGF)-β1, interleukin (IL)-10, inhibitor protein-κBα (IκBα), ribosomal S6 protein kinase 1 and target of rapamycin (TOR) and increased expression of interferon-γ2, tumor necrosis factor-α, TGF-β2, IL-1β, IL-8, IκB kinases (IKKβ and IKKγ) and nuclear factor-κB p65 (NF-κB p65). Our findings showed that thiamin deficiency reduced the immune status of fish gills. Furthermore, thiamin deficiency resulted in reduced mRNA transcript levels of claudin b, claudin 3, claudin 12, zonula occludens 1 (ZO-1) and occludin and increased mRNA transcript levels of claudin 15a, myosin light-chain kinase (MLCK) and p38 mitogen-activated protein kinase (p38 MAPK) in fish gill tissues. These data suggested that thiamin deficiency disrupted tight junction-mediated fish gill barrier function. Additionally, reactive oxygen species, malondialdehyde and protein carbonyl levels and both the activities and expression levels of Cu/Zn superoxide dismutase, catalase, glutathione peroxidase, glutathione-S-transferases and glutathione reductase, as well as NF-E2-related factor 2 gene expression in fish gills, were lower in fish fed a thiamin-deficient diet. By contrast, thiamin deficiency increased levels of Kelch-like-ECH-associated protein 1a (Keap1a) and Keap1b mRNA transcript expression in fish gills. Taken together, our findings indicated that thiamin deficiency impaired fish gill health by effects on the expression of genes encoding cytokines, tight junction proteins, antioxidant enzymes, NF-κB p65, MLCK and Nrf2.

Energy restriction impairs dendritic cell development in C57BL/6J mice

Dendritic cells (DC) are antigen-presenting cells known for stimulating naïve T lymphocytes. The sequential stages of DC development from common myeloid progenitors have been elucidated in murine bone marrow. Energy-restriction (ER) is a pro-longevity dietary intervention with mixed immunological outcomes. The objective of this study was to examine the development of DC in adult C57Bl6J mice fed a 40% ER diet. We observed increased myeloid progenitors, but decreased common DC progenitors, precursor conventional DC and plasmacytoid DC. Furthermore, we observed increased macrophages and cells expressing CD169 in the bone marrow of ER mice. There was no significant difference in DC subsets from unfractionated ER and ad libitum-fed murine bone marrow samples cultured in GM-CSF-supplemented media or Flt3L-supplemented media. Examining rates of proliferation with 6h BrdU incorporation and Ki-67 staining showed these DC progenitor populations have different proliferation rates in ER compared with AL mice. We show here, for the first time, ER results in altered myelopoiesis resulting in reduced DC development but enhanced monocyte/macrophage development in steady-state C57Bl6J mice. In conclusion, these data may partially explain prior observations of impaired early innate immune responses to primary infection such as influenza in ER mice.

Hepatocellular carcinoma and lifestyles

The majority of hepatocellular carcinoma occurs over pre-existing chronic liver diseases that share cirrhosis as an endpoint. In the last decade, a strong association between lifestyle and hepatocellular carcinoma has become evident. Abundance of energy-rich food and sedentary lifestyles have caused metabolic conditions such as obesity and diabetes mellitus to become global epidemics. Obesity and diabetes mellitus are both tightly linked to non-alcoholic fatty liver disease and also increase hepatocellular carcinoma risk independent of cirrhosis. Emerging data suggest that physical activity not only counteracts obesity, diabetes mellitus and non-alcoholic fatty liver disease, but also reduces cancer risk. Physical activity exerts significant anticancer effects in the absence of metabolic disorders. Here, we present a systematic review on lifestyles and hepatocellular carcinoma.

Methionine restriction and life-span control

Dietary restriction (DR) without malnutrition is associated with longevity in various organisms. However, it has also been shown that reduced calorie intake is often ineffective in extending life span. Selecting optimal dietary regimens for DR studies is complicated, as the same regimen may lead to different outcomes depending on genotype and environmental factors. Recent studies suggested that interventions such as moderate protein restriction with or without adequate nutrition (e.g., particular amino acids or carbohydrates) may have additional beneficial effects mediated by certain metabolic and hormonal factors implicated in the biology of aging, regardless of total calorie intake. In particular, it was shown that restriction of a single amino acid, methionine, can mimic the effects of DR and extend life span in various model organisms. We discuss the beneficial effects of a methionine-restricted diet, the molecular pathways involved, and the use of this regimen in longevity interventions.

Ketogenic diet delays the phase of circadian rhythms and does not affect AMP-activated protein kinase (AMPK) in mouse liver

Ketogenic diet (KD) is used for weight loss or to treat epilepsy. KD leads to liver AMP-activated protein kinase (AMPK) activation, which would be expected to inhibit gluconeogenesis. However, KD leads to increased hepatic glucose output. As AMPK and its active phosphorylated form (pAMPK) show circadian oscillation, this discrepancy could stem from wrong-time-of-day sampling. The effect of KD was tested on mouse clock gene expression, AMPK, mTOR, SIRT1 and locomotor activity for 2 months and compared to low-fat diet (LFD). KD led to 1.5-fold increased levels of blood glucose and insulin. Brain pAMPK/AMPK ratio was 40% higher under KD, whereas that in liver was not affected. KD led to 40% and 20% down-regulation of the ratio of pP70S6K/P70S6K, the downstream target of mTOR, in the brain and liver, respectively. SIRT1 levels were 40% higher in the brain, but 40% lower in the liver of KD-fed mice. Clock genes showed delayed rhythms under KD. In the brain of KD-fed mice, amplitudes of clock genes were down-regulated, whereas 6-fold up-regulation was found in the liver. The metabolic state under KD indicates reduced satiety in the brain and reduced anabolism alongside increased gluconeogenesis in the liver.

Chronic Dietary Administration of the Glycolytic Inhibitor 2-Deoxy-D-Glucose (2-DG) Inhibits the Growth of Implanted Ehrlich's Ascites Tumor in Mice

Background

Dietary energy restriction (DER) has been well established as a potent anticancer strategy. Non-adoption of restricted diet for an extended period has limited its practical implementation in humans with a compelling need to develop agents that mimic effects similar to DER, without reduction in actual dietary intake. Glycolytic inhibitor, 2-deoxy-D-glucose (2-DG), has recently been shown to possess potential as an energy restriction mimetic agent (ERMA). In the present study we evaluated the effect of dietary 2-DG administration on a mouse tumor model, with a focus on several potential mechanisms that may account for the inhibition of tumorigenesis.

Methodology/Principal Findings

Swiss albino strain ‘A’ mice were administered with 0.2% and 0.4% w/v 2-DG in drinking water for 3 months prior to tumor implantation (Ehrlich’s ascites carcinoma; EAC) and continued till the termination of the study with no adverse effects on general physiology and animal growth. Dietary 2-DG significantly reduced the tumor incidence, delayed the onset, and compromised the tumor growth along with enhanced survival. We observed reduced blood glucose and serum insulin levels along with decreased proliferating cell nuclear antigen (PCNA) and bromodeoxyuridine positive (BrdU⁺) tumor cells in 2-DG fed mice. Also, reduced levels of certain key players of metabolic pathways such as phosphatidylinositol 3-kinase (PI3K), phosphorylated-Akt and hypoxia inducible factor-1 alpha (HIF-1α) were also noted in tumors of 2-DG fed mice. Further, decrease in CD4⁺/CD8⁺ ratio and T-regulatory cells observed in 2-DG fed mice suggested enhanced antitumor immunity and T cell effector function.

Conclusion/Significance

These results strongly suggest that dietary 2-DG administration in mice, at doses easily achievable in humans, suitably modulates several pleotrophic factors mimicking DER and inhibits tumorigenesis, emphasizing the use of ERMAs as a promising cancer preventive strategy.

Calories, carbohydrates, and cancer therapy with radiation: exploiting the five R's through dietary manipulation

Aggressive tumors typically demonstrate a high glycolytic rate, which results in resistance to radiation therapy and cancer progression via several molecular and physiologic mechanisms. Intriguingly, many of these mechanisms utilize the same molecular pathways that are altered through calorie and/or carbohydrate restriction. Furthermore, poorer prognosis in cancer patients who display a glycolytic phenotype characterized by metabolic alterations, such as obesity and diabetes, is now well established, providing another link between metabolic pathways and cancer progression. We review the possible roles for calorie restriction (CR) and very low carbohydrate ketogenic diets (KDs) in modulating the five R's of radiotherapy to improve the therapeutic window between tumor control and normal tissue complication probability. Important mechanisms we discuss include (1) improved DNA repair in normal, but not tumor cells; (2) inhibition of tumor cell repopulation through modulation of the PI3K-Akt-mTORC1 pathway downstream of insulin and IGF1; (3) redistribution of normal cells into more radioresistant phases of the cell cycle; (4) normalization of the tumor vasculature by targeting hypoxia-inducible factor-1α downstream of the PI3K-Akt-mTOR pathway; (5) increasing the intrinsic radioresistance of normal cells through ketone bodies but decreasing that of tumor cells by targeting glycolysis. These mechanisms are discussed in the framework of animal and human studies, taking into account the commonalities and differences between CR and KDs. We conclude that CR and KDs may act synergistically with radiation therapy for the treatment of cancer patients and provide some guidelines for implementing these dietary interventions into clinical practice.