Roles of caloric restriction, ketogenic diet and intermittent fasting during initiation, progression and metastasis of cancer in animal models: a systematic review and meta-analysis

Metabolomics in cancer research and emerging applications in clinical oncology

Cancer has myriad effects on metabolism that include both rewiring of intracellular metabolism to enable cancer cells to proliferate inappropriately and adapt to the tumor microenvironment, and changes in normal tissue metabolism. With the recognition that fluorodeoxyglucose-positron emission tomography imaging is an important tool for the management of many cancers, other metabolites in biological samples have been in the spotlight for cancer diagnosis, monitoring, and therapy. Metabolomics is the global analysis of small molecule metabolites that like other -omics technologies can provide critical information about the cancer state that are otherwise not apparent. Here, the authors review how cancer and cancer therapies interact with metabolism at the cellular and systemic levels. An overview of metabolomics is provided with a focus on currently available technologies and how they have been applied in the clinical and translational research setting. The authors also discuss how metabolomics could be further leveraged in the future to improve the management of patients with cancer.

Visceral Adiposity and Cancer: Role in Pathogenesis and Prognosis

The prevalence of being overweight and obese has been expanded dramatically in recent years worldwide. Obesity usually occurs when the energetic introit overtakes energy expenditure from metabolic and physical activity, leading to fat accumulation mainly in the visceral depots. Excessive fat accumulation represents a risk factor for many chronic diseases, including cancer. Adiposity, chronic low-grade inflammation, and hyperinsulinemia are essential factors of obesity that also play a crucial role in tumor onset. In recent years, several strategies have been pointed toward boundary fat accumulation, thus limiting the burden of cancer attributable to obesity. While remodeling fat via adipocytes browning seems a tempting prospect, lifestyle interventions still represent the main pathway to prevent cancer and enhance the efficacy of treatments. Specifically, the Mediterranean Diet stands out as one of the best dietary approaches to curtail visceral adiposity and, therefore, cancer risk. In this Review, the close relationship between obesity and cancer has been investigated, highlighting the biological mechanisms at the basis of this link. Finally, strategies to remodel fat, including browning and lifestyle interventions, have been taken into consideration as a major perspective to limit excess body weight and tumor onset.

Intermittent fasting: from calories to time restriction

The global human population has recently experienced an increase in life expectancy with a mounting concern about the steady rise in the incidence of age-associated chronic diseases and socio-economic burden. Calorie restriction (CR), the reduction of energy intake without malnutrition, is a dietary manipulation that can increase health and longevity in most model organisms. However, the practice of CR in day-to-day life is a challenging long-term goal for human intervention. Recently, daily fasting length and periodicity have emerged as potential drivers behind CR's beneficial health effects. Numerous strategies and eating patterns have been successfully developed to recapitulate many of CR's benefits without its austerity. These novel feeding protocols range from shortened meal timing designed to interact with our circadian system (e.g., daily time-restricted feeding) to more extended fasting regimens known as intermittent fasting. Here, we provide a glimpse of the current status of knowledge on different strategies to reap the benefits of CR on metabolic health in murine models and in humans, without the rigor of continuous reduction in caloric intake as presented at the USU State of the Science Symposium.

Perspective: The Saturated Fat-Unsaturated Oil Dilemma: Relations of Dietary Fatty Acids and Serum Cholesterol, Atherosclerosis, Inflammation, Cancer, and All-Cause Mortality

PUFAs are known to regulate cholesterol synthesis and cellular uptake by multiple mechanisms that do not involve SFAs. Polymorphisms in any of the numerous proteins involved in cholesterol homeostasis, as a result of genetic variation, could lead to higher or lower serum cholesterol. PUFAs are susceptible to lipid peroxidation, which can lead to oxidative stress, inflammation, atherosclerosis, cancer, and disorders associated with inflammation, such as insulin resistance, arthritis, and numerous inflammatory syndromes. Eicosanoids from arachidonic acid are among the most powerful mediators that initiate an immune response, and a wide range of PUFA metabolites regulate numerous physiological processes. There is a misconception that dietary SFAs can cause inflammation, although endogenous palmitic acid is converted to ceramides and other cell constituents involved in an inflammatory response after it is initiated by lipid mediators derived from PUFAs. This article will discuss the many misconceptions regarding how dietary lipids regulate serum cholesterol, the fact that all-cause death rate is higher in humans with low compared with normal or moderately elevated serum total cholesterol, the numerous adverse effects of increasing dietary PUFAs or carbohydrate relative to SFAs, as well as metabolic conversion of PUFAs to SFAs and MUFAs as a protective mechanism. Consequently, dietary saturated fats seem to be less harmful than the proposed alternatives.

Modeling transcriptomic age using knowledge-primed artificial neural networks

The development of 'age clocks', machine learning models predicting age from biological data, has been a major milestone in the search for reliable markers of biological age and has since become an invaluable tool in aging research. However, beyond their unquestionable utility, current clocks offer little insight into the molecular biological processes driving aging, and their inner workings often remain non-transparent. Here we propose a new type of age clock, one that couples predictivity with interpretability of the underlying biology, achieved through the incorporation of prior knowledge into the model design. The clock, an artificial neural network constructed according to well-described biological pathways, allows the prediction of age from gene expression data of skin tissue with high accuracy, while at the same time capturing and revealing aging states of the pathways driving the prediction. The model recapitulates known associations of aging gene knockdowns in simulation experiments and demonstrates its utility in deciphering the main pathways by which accelerated aging conditions such as Hutchinson-Gilford progeria syndrome, as well as pro-longevity interventions like caloric restriction, exert their effects.

Cannabinoid Receptors Overexpression in a Rat Model of Irritable Bowel Syndrome (IBS) after Treatment with a Ketogenic Diet

The administration of a ketogenic diet (KD) has been considered therapeutic in subjects with irritable bowel syndrome (IBS). This study aimed to investigate the molecular mechanisms by which a low-carbohydrate diet, such as KD, can improve gastrointestinal symptoms and functions in an animal model of IBS by evaluating possible changes in intestinal tissue expression of endocannabinoid receptors. In rats fed a KD, we detected a significant restoration of cell damage to the intestinal crypt base, a histological feature of IBS condition, and upregulation of CB1 and CB2 receptors. The diet also affected glucose metabolism and intestinal membrane permeability, with an overexpression of the glucose transporter GLUT1 and tight junction proteins in treated rats. The present data suggest that CB receptors represent one of the molecular pathways through which the KD works and support possible cannabinoid-mediated protection at the intestinal level in the IBS rats after dietary treatment.

Reduced High-Dose Radiation-Induced Residual Genotoxic Damage by Induction of Radioadaptive Response and Prophylactic Mild Dietary Restriction in Mice

Radioadaptive response (RAR) describes a phenomenon in a variety of in vitro and in vivo systems that a low-dose of priming ionizing radiation (IR) reduces detrimental effects of a subsequent challenge IR at higher doses. Among in vivo investigations, studies using the mouse RAR model (Yonezawa Effect) showed that RAR could significantly extenuate high-dose IR-induced detrimental effects such as decrease of hematopoietic stem cells and progenitor cells, acute radiation hematopoietic syndrome, genotoxicity and genomic instability. Meanwhile, it has been demonstrated that diet intervention has a great impact on health, and dietary restriction shows beneficial effects on numerous diseases in animal models. In this work, by using the mouse RAR model and mild dietary restriction (MDR), we confirmed that combination of RAR and MDR could more efficiently reduce radiogenotoxic damage without significant change of the RAR phenotype. These findings suggested that MDR may share some common pathways with RAR to activate mechanisms consequently resulting in suppression of genotoxicity. As MDR could also increase resistance to chemotherapy and radiotherapy in normal cells, we propose that combination of MDR, RAR, and other cancer treatments (i.e., chemotherapy and radiotherapy) represent a potential strategy to increase the treatment efficacy and prevent IR risk in humans.

Impact of Lifestyle Behaviors on Cancer Risk and Prevention

Cancer incidences are rising globally. Therefore, in order to prevent and treat cancer, understanding cancer pathology is crucial. Tumors reprogram their metabolic phenotype to meet their needs for bioenergy, biosynthesis, and redox control. Alteration of the metabolic pathway has been proposed as the hallmark of cancer and explains the distinction between normal and cancer cells concerning nutrient utilization. Changes in the metabolism of nutrients such as glucose, amino acid, and fatty acid are associated with cancer risk. Luckily, this can be controlled with lifestyle modifications. Improvements in lifestyle behaviors to reduce cancer risks include a healthy diet, calorie restriction, and regular physical activity. This review begins with the understandings of metabolic reprogramming in cancer. Then, there will be evidence on the correlation between lifestyle factors and altered nutrient metabolism suggesting an application of lifestyle intervention for cancer risk reduction.

Roles of adiponectin and leptin signaling-related microRNAs in the preventive effects of calorie restriction in mammary tumor development

Calorie restriction (CR) is suggested to prevent the development of mammary tumors (MTs); however, the mechanism remains to be clarified. We aimed to determine the microRNA (miRNA) profile in mice applied to 2 different CR protocols; chronic (CCR) and intermittent (ICR) and follow the MT development. In addition, the roles of miRNAs involved in adiponectin and/or leptin signaling pathways were investigated. Mice were divided into 3 groups: ad-libitum (AL), CCR, or ICR, which comprised 3 weeks of AL feeding followed by 1 week of 60% CR in a cyclic manner. Blood and tissue collection were performed at weeks 10, 17/18, 49/50 and 81/82. Long-term CCR provided better protection compared with ICR for MT development with a delay in the MT occurrence. Adiponectin expression in mammary fat pad were significantly higher in CCR group compared with AL. Using GeneChip Array, 250 of 3195 miRNAs were differentially expressed among the dietary groups. Thirteen of 250 miRNAs were related to adiponectin and/or leptin signaling genes. Results were verified by reverse transcription polymerase chain reaction. Specifically, miR-326-3p, miR-500-3p and miR-129-5p, which are related to adiponectin and/or leptin signaling, may play important roles in the preventive effects of CR in MT development and in ageing. Thus, these miRNAs might be putative biomarkers to target for diagnostic and treatment purposes. Novelty: Type of CR and micro RNA interaction is related to ageing. miR-326-3p, miR-500-3p and miR-129-5p expression levels were differentially expressed in MT development and in ageing. The genes associated with adiponectin and/or leptin signaling pathways are regulated by certain miRNAs in the protective effects of CR.

Fasting and fasting-mimicking diets for chemotherapy augmentation

The increasingly older population in most developed countries will likely experience aging-related chronic diseases such as diabetes, metabolic syndrome, heart and lung diseases, osteoporosis, arthritis, dementia, and/or cancer. Genetic and environmental factors, but also lifestyle choices including physical activity and dietary habits, play essential roles in disease onset and progression. Sixty-five percent of Americans diagnosed with cancer now survive more than 5 years, making the need for informed lifestyle choices particularly important to successfully complete their treatment, increase the recovery from the cytotoxic therapy options, and improve cancer-free survival. This review will discuss the findings on the use of prolonged fasting, as well as fasting-mimicking diets to augment cancer treatment. Preclinical studies in rodents strongly support the implementation of these dietary interventions and a small number of clinical trials begin to provide encouraging results for cancer patients and cancer survivors.

Ketogenic Diet for Malignant Gliomas: a Review

PURPOSE OF REVIEW

In this review, we examine the postulated mechanisms of therapeutic effect of ketogenic diets in the treatment of gliomas, review the completed clinical trials, and discuss further directions in this field.

RECENT FINDINGS

Cancers including gliomas are characterized by derangements in cellular metabolism. In vitro and animal studies have revealed that dietary interventions to reduce glucose and glycolytic pathways in gliomas may have a therapeutic effect. Early trials in patients with malignant gliomas have shown feasibility, but are not robust enough yet to demonstrate clinical applicability. Therapies for malignant gliomas of the brain are increasingly using a multi-targeted approach. The use of ketogenic diets and its variants may offer a unique and promising anti-glioma treatment by exploiting metabolic alterations seen in cancers including gliomas seen at the cellular level, which may work in concert with other therapies.

Obesity and Cancer Metastasis: Molecular and Translational Perspectives

Obesity is a modern health problem that has reached pandemic proportions. It is an established risk factor for carcinogenesis, however, evidence for the contribution of adipose tissue to the metastatic behavior of tumors is also mounting. Over 90% of cancer mortality is attributed to metastasis and metastatic tumor cells must communicate with their microenvironment for survival. Many of the characteristics observed in obese adipose tissue strongly mirror the tumor microenvironment. Thus in the case of prostate, pancreatic and breast cancer and esophageal adenocarcinoma, which are all located in close anatomical proximity to an adipose tissue depot, the adjacent fat provides an ideal microenvironment to enhance tumor growth, progression and metastasis. Adipocytes provide adipokines, fatty acids and other soluble factors to tumor cells whilst immune cells infiltrate the tumor microenvironment. In addition, there are emerging studies on the role of the extracellular vesicles secreted from adipose tissue, and the extracellular matrix itself, as drivers of obesity-induced metastasis. In the present review, we discuss the major mechanisms responsible for the obesity-metastatic link. Furthermore, understanding these complex mechanisms will provide novel therapies to halt the tumor-adipose tissue crosstalk with the ultimate aim of inhibiting tumor progression and metastatic growth.

Could ketogenic diet "starve" cancer? Emerging evidence

Cancer cells (CCs) predominantly use aerobic glycolysis (Warburg effect) for their metabolism. This important characteristic of CCs represents a potential metabolic pathway to be targeted in the context of tumor treatment. Being this mechanism related to nutrient oxidation, dietary manipulation has been hypothesized as an important strategy during tumor treatment. Ketogenic diet (KD) is a dietary pattern characterized by high fat intake, moderate-to-low protein consumption, and very-low-carbohydrate intake (<50 g), which in cancer setting may target CCs metabolism, potentially influencing both tumor treatment and prognosis. Several mechanisms, far beyond the originally proposed inhibition of glucose/insulin signaling, can underpin the effectiveness of KD in cancer management, ranging from oxidative stress, mitochondrial metabolism, and inflammation. The role of a qualified Nutritionist is essential to reduce and manage the short and long-term complications of this dietary therapy, which must be personalized to the individual patient for the planning of tailored KD protocol in cancer patients. In the present review, we summarize the proposed antitumor mechanisms of KD, the application of KD in cancer patients with obesity and cachexia, and the preclinical and clinical evidence on KD therapy in cancer.

How Far Are We from Prescribing Fasting as Anticancer Medicine?

(1) Background: the present review provides a comprehensive and up-to date overview of the potential exploitation of fasting as an anticancer strategy. The rationale for this concept is that fasting elicits a differential stress response in the setting of unfavorable conditions, empowering the survival of normal cells, while killing cancer cells. (2) Methods: the present narrative review presents the basic aspects of the hormonal, molecular, and cellular response to fasting, focusing on the interrelationship of fasting with oxidative stress. It also presents nonclinical and clinical evidence concerning the implementation of fasting as adjuvant to chemotherapy, highlighting current challenges and future perspectives. (3) Results: there is ample nonclinical evidence indicating that fasting can mitigate the toxicity of chemotherapy and/or increase the efficacy of chemotherapy. The relevant clinical research is encouraging, albeit still in its infancy. The path forward for implementing fasting in oncology is a personalized approach, entailing counteraction of current challenges, including: (i) patient selection; (ii) fasting patterns; (iii) timeline of fasting and refeeding; (iv) validation of biomarkers for assessment of fasting; and (v) establishment of protocols for patients’ monitoring. (4) Conclusion: prescribing fasting as anticancer medicine may not be far away if large randomized clinical trials consolidate its safety and efficacy.

Quality of life and illness perceptions in patients with breast cancer using a fasting mimicking diet as an adjunct to neoadjuvant chemotherapy in the phase 2 DIRECT (BOOG 2013-14) trial

Purpose

In the phase II DIRECT study a fasting mimicking diet (FMD) improved the clinical response to neoadjuvant chemotherapy as compared to a regular diet. Quality of Life (QoL) and illness perceptions regarding the possible side effects of chemotherapy and the FMD were secondary outcomes of the trial.

Methods

131 patients with HER2-negative stage II/III breast cancer were recruited, of whom 129 were randomly assigned (1:1) to receive either a fasting mimicking diet (FMD) or their regular diet for 3 days prior to and the day of neoadjuvant chemotherapy. The European Organisation for Research and Treatment of Cancer (EORTC) questionnaires EORTC-QLQ-C30 and EORTC-QLQ-BR23; the Brief Illness Perception Questionnaire (BIPQ) and the Distress Thermometer were used to assess these outcomes at baseline, halfway chemotherapy, before the last cycle of chemotherapy and 6 months after surgery.

Results

Overall QoL and distress scores declined during treatment in both arms and returned to baseline values 6 months after surgery. However, patients’ perceptions differed slightly over time. In particular, patients receiving the FMD were less concerned and had better understanding of the possible adverse effects of their treatment in comparison with patients on a regular diet. Per-protocol analyses yielded better emotional, physical, role, cognitive and social functioning scores as well as lower fatigue, nausea and insomnia symptom scores for patients adherent to the FMD in comparison with non-adherent patients and patients on their regular diet.

Conclusions

FMD as an adjunct to neoadjuvant chemotherapy appears to improve certain QoL and illness perception domains in patients with HER2-negative breast cancer.

Trialregister

ClinicalTrials.gov Identifier: NCT02126449.

Electronic supplementary material

The online version of this article (10.1007/s10549-020-05991-x) contains supplementary material, which is available to authorized users.

Ketogenic diet feeding improves aerobic metabolism property in extensor digitorum longus muscle of sedentary male rats

Recent studies of the ketogenic diet, an extremely high-fat diet with extremely low carbohydrates, suggest that it changes the energy metabolism properties of skeletal muscle. However, ketogenic diet effects on muscle metabolic characteristics are diverse and sometimes countervailing. Furthermore, ketogenic diet effects on skeletal muscle performance are unknown. After male Wistar rats (8 weeks of age) were assigned randomly to a control group (CON) and a ketogenic diet group (KD), they were fed for 4 weeks respectively with a control diet (10% fat, 10% protein, 80% carbohydrate) and a ketogenic diet (90% fat, 10% protein, 0% carbohydrate). After the 4-week feeding period, the extensor digitorum longus (EDL) muscle was evaluated ex vivo for twitch force, tetanic force, and fatigue. We also analyzed the myosin heavy chain composition, protein expression of metabolic enzymes and regulatory factors, and citrate synthase activity. No significant difference was found between CON and KD in twitch or tetanic forces or muscle fatigue. However, the KD citrate synthase activity and the protein expression of Sema3A, citrate synthase, succinate dehydrogenase, cytochrome c oxidase subunit 4, and 3-hydroxyacyl-CoA dehydrogenase were significantly higher than those of CON. Moreover, a myosin heavy chain shift occurred from type IIb to IIx in KD. These results demonstrated that the 4-week ketogenic diet improves skeletal muscle aerobic capacity without obstructing muscle contractile function in sedentary male rats and suggest involvement of Sema3A in the myosin heavy chain shift of EDL muscle.

Ketogenic diet: a tool for the management of neuroendocrine neoplasms?

Neuroendocrine neoplasms (NENs) are a heterogeneous group of neoplasms, whose incidence has rapidly increased in the last years. Nutrition plays an important role in their management; indeed, malnutrition negatively impacts on rates of complications, hospitalization, hospital stay, costs and mortality. Furthermore, it has been reported that a poor nutritional status could influence the outcome of patients with pancreatic NENs. Moreover, obesity, predisposing to insulin resistance and compensatory hyperinsulinemia, could stimulate the growth of these neoplasms. Ketogenic diet (KD), a high-fat, low-carbohydrate diet with adequate amounts of protein, has been reported to be a promising approach for the management of several types of cancer, mostly gynecological and neurological ones. Indeed, it appears to sensitize most cancers to standard treatment by exploiting the reprogramed metabolism of cancer cells and thus resulting in a promising candidate as an adjuvant cancer therapy. Thus, the aim of this review is to provide an overview on the importance of nutrition in cancer management and in particular in NENs' setting. Furthermore, we reported the current evidence on the efficacy of KD in the management of cancer and based on molecular mechanisms; we also hypothesize the potential use of this nutritional pattern in the management of NENs.

Therapeutic Time-restricted Feeding Reduces Renal Tumor Bioluminescence in Mice but Fails to Improve Anti-CTLA-4 Efficacy

BACKGROUND/AIM

Dietary interventions like time-restricted feeding (TRF) show promising anti-cancer properties. We examined whether therapeutic TRF alone or combined with immunotherapy would diminish renal tumor growth in mice of varying body weights.

MATERIALS AND METHODS

Young (7 week) chow-fed or older (27 week) high-fat diet (HFD)-fed BALB/c mice were orthotopically injected with renal tumor cells expressing luciferase. After tumor establishment, mice were randomized to ad libitum feeding or TRF +/- anti-CTLA-4. Body composition, tumor viability and growth, and immune responses were quantified.

RESULTS

TRF alone reduced renal tumor bioluminescence in older HFD-fed, but not young chow-fed mice. In the latter, TRF mitigated tumor-induced loss of lean- and fat-mass. However, TRF did not alter excised renal tumor weights or intratumoral immune responses and failed to improve anti-CTLA-4 outcomes in any mice.

CONCLUSION

Therapeutic TRF exhibits modest anti-cancer properties but fails to improve anti-CTLA-4 immune checkpoint blockade in murine renal cancer.

The effect of caloric restriction and fasting on cancer

Cancer is one of the most frequent causes of worldwide death and morbidity and is a major public health problem. Although, there are several widely used treatment methods including chemo-, immune- and radiotherapies, these mostly lack sufficient efficiency and induce toxicities in normal surrounding tissues. Thus, finding new approaches to mitigate side effects and potentially accelerate treatment is paramount. In line with this, increasing preclinical evidence indicates that caloric restriction (CR) and fasting might have anticancer effects by reducing tumor progression, enhancing death of cancer cells, and elevating the effectiveness and tolerability of chemo- and radiotherapies. Nonetheless, clinical studies assessing the potential of CR and fasting in cancer are scarce and inconsistent, and more investigations are still required to clarify their effect in different aspects of cancer treatment. In this review, we have summarized the findings of preclinical and clinical studies of CR and fasting with respect to efficacy and on the adverse effects of standard cancer treatments.

Feasibility, Process, and Effects of Short-Term Calorie Reduction in Cancer Patients Receiving Chemotherapy: An Integrative Review

Recent preclinical studies have shown the potential benefits of short-term calorie reduction (SCR) on cancer treatment. In this integrative review, we aimed to identify and synthesize current evidence regarding the feasibility, process, and effects of SCR in cancer patients receiving chemotherapy. PubMed, Cumulative Index to Nursing and Allied Health Literature, Ovid Medline, PsychINFO, and Embase were searched for original research articles using various combinations of Medical Subject Heading terms. Among the 311 articles identified, seven studies met the inclusion criteria. The majority of the reviewed studies were small randomized controlled trials or cohort study with fair quality. The results suggest that SCR is safe and feasible. SCR is typically arranged around the chemotherapy, with the duration ranging from 24 to 96 h. Most studies examined the protective effects of SCR on normal cells during chemotherapy. The evidence supports that SCR had the potential to enhance both the physical and psychological wellbeing of patients during chemotherapy. SCR is a cost-effective intervention with great potential. Future well-controlled studies with sufficient sample sizes are needed to examine the full and long-term effects of SCR and its mechanism of action.

Cancer diets for cancer patients: Lessons from mouse studies and new insights from the study of fatty acid metabolism in tumors

Specific diets for cancer patients have the potential to offer an adjuvant modality to conventional anticancer therapy. If the concept of starving cancer cells from nutrients to inhibit tumor growth is quite simple, the translation into the clinics is not straightforward. Several diets have been described including the Calorie-restricted diet based on a reduction in carbohydrate intake and the Ketogenic diet wherein the low carbohydrate content is compensated by a high fat intake. As for other diets that deviate from normal composition only by one or two amino acids, these diets most often revealed a reduction in tumor growth in mice, in particular when associated with chemo- or radiotherapy. By contrast, in cancer patients, the interest of these diets is almost exclusively supported by case reports precluding any conclusions on their real capacity to influence disease outcome. In parallel, the field of tumor lipid metabolism has emerged in the last decade offering a better understanding of how fatty acids are captured, synthesized or stored as lipid droplets in cancers. Fatty acids participate to cancer cell survival in the hypoxic and acidic tumor microenvironment and also support proliferation and invasiveness. Interestingly, while such addiction for fatty acids may account for cancer progression associated with high fat diet, it could also represent an Achilles heel for tumors. In particular n-3 polyunsaturated fatty acids represent a class of lipids that can exert potent cytotoxic effects in tumors and therefore represent an attractive diet supplementation to improve cancer patient outcomes.

Is Host Metabolism the Missing Link to Improving Cancer Outcomes?

For the past 100 years, oncologists have relentlessly pursued the destruction of tumor cells by surgical, chemotherapeutic or radiation oncological means. Consistent with this focus, treatment plans are typically based on key characteristics of the tumor itself such as disease site, histology and staging based on local, regional and systemic dissemination. Precision medicine is similarly built on the premise that detailed knowledge of molecular alterations of tumor cells themselves enables better and more effective tumor cell destruction. Recently, host factors within the tumor microenvironment including the vasculature and immune systems have been recognized as modifiers of disease progression and are being targeted for therapeutic gain. In this review, we argue that—to optimize the impact of old and new treatment options—we need to take account of an epidemic that occurs independently of—but has major impact on—the development and treatment of malignant diseases. This is the rapidly increasing number of patients with excess weight and its’ attendant metabolic consequences, commonly described as metabolic syndrome. It is well established that patients with altered metabolism manifesting as obesity, metabolic syndrome and chronic inflammation have an increased incidence of cancer. Here, we focus on evidence that these patients also respond differently to cancer therapy including radiation and provide a perspective how exercise, diet or pharmacological agents may be harnessed to improve therapeutic responses in this patient population.

Insulin Reduces the Efficacy of Vemurafenib and Trametinib in Melanoma Cells

BACKGROUND

Despite the progress made in the clinical management of metastatic melanoma, a patient's response to treatment cannot be fully predicted, and intrinsic or acquired resistance that is developed in most melanoma patients warrants further research efforts. In addition to genetic factors, microenvironmental input should be considered to explain the diversity of response to treatment among melanoma patients. In this study, we evaluated the impact of insulin on patient-derived BRAFV600E melanoma cells, either untreated or treated with vemurafenib or trametinib, inhibitors of BRAFV600 and MEK1/2, respectively.

METHODS

Cells were cultured in serum-free conditions, either with or without insulin. The activity of the MAPK/ERK and PI3K/AKT pathways was assessed by Western blotting, cell viability, and percentages of Ki-67- and NGFR-positive cells by flow cytometry. Transcript levels were analyzed using qRT-PCR, and γ-H2AX levels by immunoblotting and confocal microscopy. A luminescence-based assay was used to measure glutathione content.

RESULTS

While insulin did not influence the MAPK/ERK pathway activity, it had a strong influence on melanoma cells, in which this pathway was suppressed by either vemurafenib or trametinib. In the presence of insulin, both drugs were much less efficient in 1) inhibiting proliferation and reducing the percentage of Ki-67-positive cells, and 2) inducing apoptosis and phosphorylation of histone H2AX in melanoma cells. Changes induced by vemurafenib and trametinib in glutathione homeostasis and DNA repair gene expression were also attenuated by insulin. Moreover, insulin impaired the combined effects of targeted drugs and doxorubicin in melanoma cells. In addition to insulin-induced PI3K/AKT activity, which was either transient or sustainable depending on the cell line, an insulin-triggered increase in the percentage of cells expressing NGFR, a marker of neural crest stem-like cells, may contribute to the reduced drug efficacy.

CONCLUSION

Our results demonstrate the role of insulin in reducing the efficacy of vemurafenib and trametinib. This needs clinical assessment.

The Molecular Link from Diet to Cancer Cell Metabolism

Malignant cells remodel their metabolism to meet the demands of uncontrolled cell proliferation. These demands lead to differential requirements in energy, biosynthetic precursors, and signaling intermediates. Both genetic programs arising from oncogenic events and transcriptional programs and epigenomic events are important in providing the necessary metabolic network activity. Accumulating evidence has established that environmental factors play a major role in shaping cancer cell metabolism. For metabolism, diet and nutrition are the major environmental aspects and have emerged as key components in determining cancer cell metabolism. In this review, we discuss these emerging concepts in cancer metabolism and how diet and nutrition influence cancer cell metabolism.

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.

A review of nutrition and dietary interventions in oncology

The complex cellular mechanisms and inter-related pathways of cancer proliferation, evasion, and metastasis remain an emerging field of research. Over the last several decades, nutritional research has prominent role in identifying emerging adjuvant therapies in our fight against cancer. Nutritional and dietary interventions are being explored to improve the morbidity and mortality for cancer patients worldwide. In this review, we examine several dietary interventions and their proposed mechanisms against cancer as well as identifying limitations in the currently available literature. This review provides a comprehensive review of the cancer metabolism, dietary interventions used during cancer treatment, anti metabolic drugs, and their impact on nutritional deficiencies along with a critical review of the following diets: caloric restriction, intermittent fasting, ketogenic diet, Mediterranean diet, Japanese diet, and vegan diet.

Managing Metastatic Thymoma With Metabolic and Medical Therapy: A Case Report

Thymomas consist of neoplastic thymic cells intermixed with variable numbers of non-neoplastic lymphocytes. Metastatic thymomas are typically managed with non-curative chemotherapy to control tumor-related symptoms; no prolonged survival is expected. Metabolic-based approaches, such as fasting and ketogenic diets, target cancer cell metabolism by creating an increased reliance on ketones while decreasing glucose, glutamine, and growth factor availability, theoretically depriving cancer cells of their metabolic fuels while creating an unfavorable environment for cancer growth, which may be beneficial in metastatic thymoma. We report the case of a 37-year-old woman with myasthenia gravis, diagnosed with an inoperable type AB, stage IVA thymoma, who pursued a metabolic intervention consisting of periodic fasting (7-day, fluid-only fasts every 1–2 months), combined with a modified ketogenic diet on feeding days, for 2 years. Fasting-related adverse effects included cold intolerance, fatigue, and generalized muscle aches, all of which resolved during the second year. She experienced two myasthenia relapses, each associated with profoundly reduced oral intake, marked weight loss, and tumor regression-the first relapse was followed by a 32% decrease in tumor volume over 4 months, the second relapse by a dramatic 96% decrease in tumor volume over 4 months. The second relapse also required prednisone to control the myasthenia symptoms. We hypothesize that 2 years of fasting and ketogenic diet therapy metabolically weakened the neoplastic thymic cell component of the thymoma, “setting the stage” for immune activation and extreme energy restriction to destroy the majority of cancer cells during both relapses, while prednisone-induced apoptosis eradicated the remaining lymphocytic component of the thymoma during the second relapse. This case is unique in that a metabolic-based fasting and ketogenic diet intervention was used as the primary management strategy for a metastatic cancer in the absence of surgery, chemotherapy, or radiotherapy, culminating in a near-complete regression. Nearly 3 years after being diagnosed with inoperable metastatic cancer, our patient shows no signs of disease and leads a full and active life.

Impact of intermittent energy restriction on anthropometric outcomes and intermediate disease markers in patients with overweight and obesity: systematic review and meta-analyses

This systematic review aims to investigate the effects of intermittent energy restriction (IER) on anthropometric outcomes and intermediate disease markers. A systematic literature search was conducted in three electronic databases. Randomized controlled trials (RCTs) were included if the intervention lasted ≥12 weeks and IER was compared with either continuous energy restriction (CER) or a usual diet. Random-effects meta-analysis was performed for eight outcomes. Certainty of evidence was assessed using GRADE. Seventeen RCTs with 1328 participants were included. IER in comparison to a usual diet may reduce body weight (mean difference [MD]: -4.83 kg, 95%-CI: -5.46, -4.21; n = 6 RCTs), waist circumference (MD: -1.73 cm, 95%-CI: -3.69, 0.24; n = 2), fat mass (MD: -2.54 kg, 95%-CI: -3.78, -1.31; n = 6), triacylglycerols (MD: -0.20 mmol/L, 95%-CI: -0.38, -0.03; n = 5) and systolic blood pressure (MD: -6.11 mmHg, 95%-CI: -9.59, -2.64; n = 5). No effects were observed for LDL-cholesterol, fasting glucose, and glycosylated-hemoglobin. Both, IER and CER have similar effect on body weight (MD: -0.55 kg, 95%-CI: -1.01, -0.09; n = 13), and fat mass (MD: -0.66 kg, 95%-CI: -1.14, -0.19; n = 10), and all other outcomes. In conclusion, IER improves anthropometric outcomes and intermediate disease markers when compared to a usual diet. The effects of IER on weight loss are similar to weight loss achieved by CER.

Sarcopenia is associated with increased mortality but not complications following resection and reconstruction of sarcoma of the extremities

BACKGROUND AND OBJECTIVES

Evidence regarding the impact of sarcopenia on operative outcomes in patients with sarcoma is lacking. We evaluated the relationship between sarcopenia and postoperative complications or mortality among patients undergoing tumor excision and reconstruction. ​ METHODS: We retrospectively reviewed 145 patients treated with tumor excision and limb reconstruction for sarcoma of the extremities. Sarcopenia was defined as psoas index (PI) < 5.45 cm² /m² for men and <3.85 cm² /m² for women from preoperative axial CT. Regression analyses were used to assess the association between postoperative complications or mortality with PI, age, gender, race, body mass index, tumor histology, grade, depth, location, size, and neoadjuvant/adjuvant therapy.

RESULTS

There were 101 soft tissue tumors and 44 primary bone tumors. Sarcopenia was present in 38 patients (26%). Sarcopenic patients were older (median age: 72 vs 59 years, P = .0010) and had larger tumors (86.5%, >5 cm vs 77.7%, P = .023). Seventy-three patients experienced complications (51%) and 18 patients died within 1 year. Sarcopenia and metastatic disease were associated with increased 12-month mortality (hazard ratio [HR] = 6.68, P < .001; HR: 8.51, P < .001, respectively) but not complications (HR 1.45, P = .155, odds ratio, 1.32, P = .426, respectively).

CONCLUSIONS

Sarcopenia and metastatic disease were independently associated with postoperative mortality but no complications following surgery.

The Effects of Graded Levels of Calorie Restriction: XIV. Global Metabolomics Screen Reveals Brown Adipose Tissue Changes in Amino Acids, Catecholamines, and Antioxidants After Short-Term Restriction in C57BL/6 Mice

Animals undergoing calorie restriction (CR) often lower their body temperature to conserve energy. Brown adipose tissue (BAT) is stimulated through norepinephrine when rapid heat production is needed, as it is highly metabolically active due to the uncoupling of the electron transport chain from ATP synthesis. To better understand how BAT metabolism changes with CR, we used metabolomics to identify 883 metabolites that were significantly differentially expressed in the BAT of C57BL/6 mice, fed graded CR (10%, 20%, 30%, and 40% CR relative to their individual baseline intake), compared with mice fed ad libitum (AL) for 12 hours a day. Pathway analysis revealed that graded CR had an impact on the TCA cycle and fatty acid degradation. In addition, an increase in nucleic acids and catecholamine pathways was seen with graded CR in the BAT metabolome. We saw increases in antioxidants with CR, suggesting a beneficial effect of mitochondrial uncoupling. Importantly, the instigator of BAT activation, norepinephrine, was increased with CR, whereas its precursors l-tyrosine and dopamine were decreased, indicating a shift of metabolites through the activation pathway. Several of these key changes were correlated with food anticipatory activity and body temperature, indicating BAT activation may be driven by responses to hunger.

Context-Dependent Roles for SIRT2 and SIRT3 in Tumor Development Upon Calorie Restriction or High Fat Diet

Calorie restriction (CR) is considered one of the most robust ways to extend life span and reduce the risk of age-related diseases, including cancer, as shown in many different organisms, whereas opposite effects have been associated with high fat diets (HFDs). Despite the proven contribution of sirtuins in mediating the effects of CR in longevity, the involvement of these nutrient sensors, specifically, in the diet-induced effects on tumorigenesis has yet to be elucidated. Previous studies focusing on SIRT1, do not support a critical role for this sirtuin family member in CR-mediated cancer prevention. However, the contribution of other family members which exhibit strong deacetylase activity is unexplored. To fill this gap, we aimed at investigating the role of SIRT2 and SIRT3 in mediating the anti and pro-tumorigenic effect of CR and HFD, respectively. Our results provide strong evidence supporting distinct, context-dependent roles played by these two family members. SIRT2 is indispensable for the protective effect of CR against tumorigenesis. On the contrary, SIRT3 exhibited oncogenic properties in the context of HFD-induced tumorigenesis, suggesting that SIRT3 inhibition may mitigate the cancer-promoting effects of HFD. Given the different functions regulated by SIRT2 and SIRT3, unraveling downstream targets/pathways involved may provide opportunities to develop new strategies for cancer prevention.

Energy Restriction and Colorectal Cancer: A Call for Additional Research

: Colorectal cancer has the second highest cancer-related mortality rate, with an estimated 881,000 deaths worldwide in 2018. The urgent need to reduce the incidence and mortality rate requires innovative strategies to improve prevention, early diagnosis, prognostic biomarkers, and treatment effectiveness. Caloric restriction (CR) is known as the most robust nutritional intervention that extends lifespan and delays the progression of age-related diseases, with remarkable results for cancer protection. Other forms of energy restriction, such as periodic fasting, intermittent fasting, or fasting-mimicking diets, with or without reduction of total calorie intake, recapitulate the effects of chronic CR and confer a wide range of beneficial effects towards health and survival, including anti-cancer properties. In this review, the known molecular, cellular, and organismal effects of energy restriction in oncology will be discussed. Energy-restriction-based strategies implemented in colorectal models and clinical trials will be also revised. While energy restriction constitutes a promising intervention for the prevention and treatment of several malignant neoplasms, further investigations are essential to dissect the interplay between fundamental aspects of energy intake, such as feeding patterns, fasting length, or diet composition, with all of them influencing health and disease or cancer effects. Currently, effectiveness, safety, and practicability of different forms of fasting to fight cancer, particularly colorectal cancer, should still be contemplated with caution.

Caloric restriction is associated with preservation of muscle strength in experimental cancer cachexia

Caloric restriction increases lifespan and healthspan, and limits age-associated muscle wasting. In this study, we investigate the impact of 30% caloric restriction (CR) in a murine cancer cachexia model. Forty CD2F1 mice were allocated as C26 tumor-bearing (TB) + ad libitum food intake (dietary reference intake [DRI]), TB CR, non-TB (NTB) CR, or NTB matched intake (MI). TB groups were inoculated subcutaneously with 0.5x10⁶ C26 cells 14 days after initiating CR. Bodyweight, food intake, and grip-strength were recorded periodically. Gastrocnemius (GCM) and tibialis anterior (TA) muscles were resected and weighed 3 weeks after tumor inoculation. mRNA expression of MuRF1, Atrogin-1, myogenin, and MyoD was determined. At tumor inoculation, the mean body weight of TB CR was 88.6% of initial body weight and remained stable until sacrifice. TB DRI showed wasting before sacrifice. TB groups experienced muscle wasting compared with NTB MI. Grip-strength change was less severe in TB CR. Expression of MuRF1, Atrogin-1, and MyoD was similar between TB DRI and both CR groups. Expression of myogenin was increased in CR groups. In conclusion, caloric restriction limits loss of muscle strength but has no impact on muscle mass despite significant loss of body weight in an experimental cancer-associated cachexia model.

Adherence to the low carbohydrate diet and the risk of breast Cancer in Iran

Background

Previous studies on the link between macronutrients and breast cancer have mostly focused on individual macronutrients rather than their combination. This study investigates the association between adherence to a low carbohydrate diet and odds of breast cancer among women.

Methods

This hospital-based case-control study was carried out on 412 women with pathologically confirmed breast cancer within the past year and 456 apparently healthy controls that were matched in terms of age and residential place. Dietary data was collected using a 168-item validated FFQ. Participants were classified in terms of quintiles of percentages of energy intake from carbohydrates, proteins, and fats. Then, individuals in the highest quintile of fat and protein intake were given a score of 5 and those in the lowest quintile of these macronutrients were given a score of 1. Participants in the other quintiles of these macronutrients were given the corresponding score. In terms of carbohydrate intake, those in the highest quintile received a score of 1 and those in the lowest quintile received 5. The scores were then summed up to calculate the total low carbohydrate diet (LCD) score, which varied from 3 to 15. A higher score meant greater adherence to a low carbohydrate diet.

Results

The mean age of study participants was 45.2 y and mean BMI was 28.4 kg/m². Mean LCD score of participants was 8.9 ± 2.5 (8.9 ± 2.6 in cases and 9.0 ± 2.5 in controls). Although no significant association was observed between adherence to the LCD score and odds of breast cancer in the study population, a trend toward significant positive association was seen between consumption of LCD and odds of breast cancer in postmenopausal women; after controlling for several potential confounders, individuals in the third quartile of LCD score were 1.94 times more likely to have breast cancer than those in the lowest quartile (95% CI: 1.00, 3.76). This association strengthened after controlling for dietary variables (2.50; 1.18–5.32). Even after further adjustment for BMI, this association remained significant (2.64, 1.23–5.67). No significant relationship was observed in premenopausal women, either before or after controlling for confounders.

Conclusion

Adherence to LCD may be associated with increased odds of breast cancer in postmenopausal women. Prospective cohort studies are needed to confirm these findings.

Postoperative serum metabolites of patients on a low carbohydrate ketogenic diet after pancreatectomy for pancreatobiliary cancer: a nontargeted metabolomics pilot study

A ketogenic diet is a potential adjuvant cancer therapy that limits glucose availability to tumours while fuelling normal tissues with ketone bodies. We examined the effect of a low carbohydrate ketogenic diet (LCKD) (80% kcal from fat, ketogenic ratio 1.75:1, w/w) compared to a general hospital diet (GD) on serum metabolic profiles in patients (n = 18, ≥ 19 years old) who underwent pancreatectomy for pancreatobiliary cancer. Serum samples collected preoperatively (week 0) and after the dietary intervention (week 2) were analysed with a nontargeted metabolomics approach using liquid chromatography-tandem mass spectrometry. Serum β-hydroxybutyrate and total ketone levels significantly increased after 2 weeks of LCKD compared to GD (p < 0.05). Principal component analysis score plots and orthogonal partial least squares discriminant analysis also showed significant differences between groups at week 2, with strong validation. In all, 240 metabolites differed between LCKD and GD. Pathways including glycerophospholipid and sphingolipid metabolisms were significantly enriched in the LCKD samples. LCKD decreased C22:1-ceramide levels, which are reported to be high in pancreatic cancer, while increasing lysophosphatidylcholine (18:2), uric acid, citrulline, and inosine levels, which are generally low in pancreatic cancer. Postoperative LCKD might beneficially modulate pancreatic cancer-related metabolites in patients with pancreatobiliary cancer.

Fasting as a Therapy in Neurological Disease

Fasting is deeply entrenched in evolution, yet its potential applications to today’s most common, disabling neurological diseases remain relatively unexplored. Fasting induces an altered metabolic state that optimizes neuron bioenergetics, plasticity, and resilience in a way that may counteract a broad array of neurological disorders. In both animals and humans, fasting prevents and treats the metabolic syndrome, a major risk factor for many neurological diseases. In animals, fasting probably prevents the formation of tumors, possibly treats established tumors, and improves tumor responses to chemotherapy. In human cancers, including cancers that involve the brain, fasting ameliorates chemotherapy-related adverse effects and may protect normal cells from chemotherapy. Fasting improves cognition, stalls age-related cognitive decline, usually slows neurodegeneration, reduces brain damage and enhances functional recovery after stroke, and mitigates the pathological and clinical features of epilepsy and multiple sclerosis in animal models. Primarily due to a lack of research, the evidence supporting fasting as a treatment in human neurological disorders, including neurodegeneration, stroke, epilepsy, and multiple sclerosis, is indirect or non-existent. Given the strength of the animal evidence, many exciting discoveries may lie ahead, awaiting future investigations into the viability of fasting as a therapy in neurological disease.

[Efficacy of a ketogenic diet in urological cancers patients : A systematic review]

BACKGROUND

Beside the classical anticancer treatment tumor patients try to find proactive alternative therapies to fight their disease. Lifestyle changes such as introducing a ketogenic diet is one of the most popular among them. The German Association of Urological Oncology (AUO, Arbeitsgemeinschaft Urologische Onkologie) presents a systematic review investigating the evidence of ketogenic diet in cancer patients.

MATERIALS AND METHODS

A systematic literature research was conducted in the databases Medline, Livivo, and the Cochrane Library. Only clinical studies of tumor patients receiving chemotherapy while on a ketogenic diet were included. The assessment of the results was performed according to the predefined primary endpoints overall survival and progression-free survival and secondary endpoints quality of life and reduction of adverse effects induced by cytostatics.

RESULTS

Nine studies met the inclusion criteria: eight prospective and one retrospective study case series respectively cohort-studies, with a total of 107 patients. Currently there is no evidence of a therapeutic effect of a ketogenic diet in patients with malignant tumors regarding the clinical outcome or quality of life.

CONCLUSION

Based on the current data, a ketogenic diet can not be recommended to cancer patients because prospective, randomized trials are missing.

The influence of fasting and energy restricting diets on IGF-1 levels in humans: A systematic review and meta-analysis

BACKGROUND

Fasting and energy restricting diets have a potential means of delaying or preventing the onset of a range of age-related metabolic and neoplastic diseases. Consistently at the centre of this effect appears to be a significant reduction in circulating IGF-1 levels. The aim of the current systematic review and meta-analysis was to determine the influence of fasting and energy restriction on IGF-1 levels in human subjects.

METHODS

A comprehensive systematic search was conducted from onset of the database to February 2019 in Embase, MEDLINE/PubMed, and SCOPUS to identify randomized clinical trials that investigating the impact of fasting or energy restriction circulating IGF-1 levels. Effect size was reported as weighted mean difference (WMD) and 95% confidence intervals (CI) using a random-effects models. Subgroup analysis was performed to identify the probable source of heterogeneity among trials.

RESULTS

Total pooling of fasting and energy restriction randomised controlled trials in WMD analysis revealed no significant effect on circulating IGF-1 levels (WMD: -16.41 ng/ml, 95% CI: -35.88, 3.07). Sub grouped analysis fasting regimens appeared to substantially reduce IGF-1 (WMD: -28.87 ng/ml, 95% CI: -43.69, -14.05, I² = 00%), energy restricting regimens failed to do the same (WMD: -10.98 ng/ml, 95% CI: -33.08, 11.11, I² = 90%). Within this final subgrouping, it was observed that only energy restriction regimens of 50% or greater of normal daily energy intake were capable of significantly reducing IGF-1 levels (WMD: -36.57 ng/ml, 95% CI: -59.19, -13.95, I² = 00%). Finally, a meta regression were noted in which the percentage restriction of daily energy intake inversely correlated with plasma IGF-1 levels (p = 0.04).

CONCLUSION

This study uncovered that fasting significantly reduced levels of IGF-1, while energy restriction diets were successful only when intake was reduced by 50% or more.

Targeting Glucose Metabolism to Enhance Immunotherapy: Emerging Evidence on Intermittent Fasting and Calorie Restriction Mimetics

There is growing interest in harnessing lifestyle and pharmaceutical interventions to boost immune function, reduce tumor growth, and improve cancer treatment efficacy while reducing treatment toxicity. Interventions targeting glucose metabolism are particularly promising, as they have the potential to directly inhibit tumor cell proliferation. However, because anti-tumor immune effector cells also rely on glycolysis to sustain their clonal expansion and function, it remains unclear whether glucose-modulating therapies will support or hinder anti-tumor immunity. In this perspective, we summarize a growing body of literature that evaluates the effects of intermittent fasting, calorie restriction mimetics, and anti-hyperglycemic agents on anti-tumor immunity and immunotherapy outcomes. Based on the limited data currently available, we contend that additional pre-clinical studies and clinical trials are warranted to address the effects of co-administration of anti-hyperglycemic agents or glucose-lowering lifestyle modifications on anti-tumor immunity and cancer treatment outcomes. We stress that there is currently insufficient evidence to provide recommendations regarding these interventions to cancer patients undergoing immunotherapy. However, if found to be safe and effective in clinical trials, interventions targeting glucose metabolism could act as low-cost combinatorial adjuvants for cancer patients receiving immune checkpoint blockade or other immunotherapies.

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.

Epigenetic Regulation of Metabolism and Inflammation by Calorie Restriction

Chronic caloric restriction (CR) without malnutrition is known to affect different cellular processes such as stem cell function, cell senescence, inflammation, and metabolism. Despite the differences in the implementation of CR, the reduction of calories produces a widespread beneficial effect in noncommunicable chronic diseases, which can be explained by improvements in immuno-metabolic adaptation. Cellular adaptation that occurs in response to dietary patterns can be explained by alterations in epigenetic mechanisms such as DNA methylation, histone modifications, and microRNA. In this review, we define these modifications and systematically summarize the current evidence related to CR and the epigenome. We then explain the significance of genome-wide epigenetic modifications in the context of disease development. Although substantial evidence exists for the widespread effect of CR on longevity, there is no consensus regarding the epigenetic regulations of the underlying cellular mechanisms that lead to improved health. We provide compelling evidence that CR produces long-lasting epigenetic effects that mediate expression of genes related to immuno-metabolic processes. Epigenetic reprogramming of the underlying chronic low-grade inflammation by CR can lead to immuno-metabolic adaptations that enhance quality of life, extend lifespan, and delay chronic disease onset.

Intermittent Fasting Exacerbates the Acute Immune and Behavioral Sickness Response to the Viral Mimic Poly(I:C) in Mice

Intermitted fasting and other forms of calorie restriction are increasingly demonstrated to exert potential health benefits. Interestingly, restricted feeding is also able to mitigate sickness in response to bacterial factors stimulating Toll-like receptor 4 (TLR4). However, little is known about how fasting modifies the activity of virus-associated molecular patterns. We therefore analyzed the impact of an intermittent fasting (IF) regimen on the immune and behavioral response to the TLR3 agonist and viral mimic polyinosinic:polycytidylic acid [Poly(I:C)] in mice. The effects of intraperitoneally injected Poly(I:C) (12 mg/kg) on plasma and cerebral cytokine expression and behavior (locomotion, exploration, and ingestion) were examined in male C57BL/6N mice under control conditions and following a 9 days period of intermittent (alternate day) fasting (IF). Poly(I:C) increased the circulating levels of cytokines (TNF-α, MCP-1, IL-6, IL-10, IFN-α, IFN-γ), an effect amplified by IF. In addition, IF aggravated sickness behavior in response to Poly(I:C), while cerebral cytokine expression was enhanced by application of Poly(I:C) in the absence of a significant effect of IF. Furthermore, IF augmented the expression of neuropeptide Y (NPY) mRNA in the hypothalamus and increased the plasma levels of corticosterone, while Poly(I:C) had little effect on these readouts. Our data show that IF does not abate, but exaggerates the immune and sickness response to the viral mimic Poly(I:C). This adverse effect of IF occurs despite increased hypothalamic NPY expression and enhanced plasma corticosterone. We therefore propose that the effects of IF on the immune and behavioral responses to viral and bacterial factors are subject to different neuronal and neuroendocrine control mechanisms.

Senolytics and senostatics as adjuvant tumour therapy

Cell senescence is a driver of ageing, frailty, age-associated disease and functional decline. In oncology, tumour cell senescence may contribute to the effect of adjuvant therapies, as it blocks tumour growth. However, this is frequently incomplete, and tumour cells that recover from senescence may gain a more stem-like state with increased proliferative potential. This might be exaggerated by the induction of senescence in the surrounding niche cells. Finally, senescence will spread through bystander effects, possibly overwhelming the capacity of the immune system to ablate senescent cells. This induces a persistent system-wide senescent cell accumulation, which we hypothesize is the cause for the premature frailty, multi-morbidity and increased mortality in cancer survivors. Senolytics, drugs that selectively kill senescent cells, have been developed recently and have been proposed as second-line adjuvant tumour therapy. Similarly, by blocking accelerated senescence following therapy, senolytics might prevent and potentially even revert premature frailty in cancer survivors. Adjuvant senostatic interventions, which suppress senescence-associated bystander signalling, might also have therapeutic potential. This becomes pertinent because treatments that are senostatic in vitro (e.g. dietary restriction mimetics) persistently reduce numbers of senescent cells in vivo, i.e. act as net senolytics in immunocompetent hosts.

Treatment of malignant gliomas with ketogenic or caloric restricted diets: A systematic review of preclinical and early clinical studies

BACKGROUND & AIMS

Patients with malignant gliomas have a poor prognosis. Diets that lower blood glucose, such as ketogenic or caloric restricted diets (KCRDs), are hypothesized to reduce tumor growth and improve survival. In this systematic review, we summarize preclinical and clinical data on KCRDs in gliomas.

METHODS

We searched PubMed and Embase for preclinical and clinical studies on KCRDs in gliomas, and extracted data on surrogate and clinically relevant endpoints, in accordance with PRISMA statement. Quality assessment of clinical studies was performed with use of Cochrane Collaboration's tool. We performed Fisher's exact test to examine associations between surrogate and clinically relevant endpoints.

RESULTS

We included 24 preclinical studies, seven clinical studies and one mixed study. Both preclinical and clinical studies were highly heterogeneous. Preclinically, KCRDs reduced tumor growth, but only a small majority of the in vivo studies found improved survival. These effects were stronger in groups with decreased blood glucose than in those with increased ketones, and also when other therapies were used concomitantly. Finally, KCRDs influence multiple molecular-biological pathways, including the PTEN/Akt/TSC2 and NF-kB pathway. In clinical studies, KCRDs seem to be safe and feasible in glioma patients. Clinical data were insufficient to draw conclusions regarding efficacy.

CONCLUSIONS

KCRDs have positive effects on malignant gliomas in published preclinical studies. Preliminary clinical data suggest that KCRDs are safe and feasible. However, because of the paucity of clinical data, the efficacy of KCRDs for improving survival and quality of life of glioma patients remains to be proven in prospective studies.

An 8-Week, Low Carbohydrate, High Fat, Ketogenic Diet Enhanced Exhaustive Exercise Capacity in Mice Part 2: Effect on Fatigue Recovery, Post-Exercise Biomarkers and Anti-Oxidation Capacity

A low-carbohydrate, high-fat ketogenic diet (KD) is a nutritional approach ensuring that the body utilizes lipids. In our previous study, we found that an eight-week ketogenic high-fat, low-carbohydrate diet increased the capacity of endurance exercise in mice without aggravated muscle injury, despite the decrease of absolute muscle volume. The potential mechanism is most possibly to be enhanced capacity to mobilize and utilize fat. In the present study, we investigated whether a ketogenic diet influences post-exercise recovery by measuring blood biomarkers, muscle and liver oxidative state as well as fatigue recovery 24 h post exercise by employing an open-field locomotion test. Several biochemistry markers indicating exercise-induced injury after exhaustive exercise were improved by KD, followed by a 24-h rest with free feed access, including lactate. No aggravated hepatic oxidative damage was observed, whereas muscular oxidative stress was increased by KD. Accelerated recovery induced by exhaustive exercise was also observed from blood biomarkers of injury. For fatigue recovery, lactate concentration, a marker often employed as exhaustion index was lowered by KD, whereas an open field test showed that KD application contributed to increased locomotion after exhaustive exercise, followed by a 24-h rest. These results suggest that KD has the potential to be used as a fatigue-preventing and/or recovery-promoting diet approach in endurance athletes.