A switch from white to brown fat increases energy expenditure in cancer-associated cachexia

Skeletal muscle endothelial dysfunction through the activin A-PGC1α axis drives progression of cancer cachexia

Cachexia is the wasting of skeletal muscle in cancer and is a major complication that impacts a person's quality of life. We hypothesized that cachexia is mediated by dysfunction of the vascular system, which is essential for maintaining perfusion and tempering inappropriate immune responses. Using transparent tissue topography, we discovered that loss of muscle vascular density precedes muscle wasting in multiple complementary tumor models, including pancreatic adenocarcinoma, colon carcinoma, lung adenocarcinoma and melanoma models. We also observed that persons suffering from cancer cachexia exhibit substantial loss of muscle vascular density. As tumors progress, increased circulating activin A remotely suppresses the expression of peroxisome proliferator-activated receptor-γ coactivator 1α (PGC1α) in the muscle endothelium, thus inducing vascular leakage. Restoring endothelial PGC1α activity preserved vascular density and muscle mass in tumor-bearing mice. Our study suggests that restoring muscle endothelial function could be a valuable therapeutic approach for cancer cachexia.

Zinc-alpha-2-glycoprotein overexpression and maintaining anti-apoptotic function in oral squamous cell carcinoma

OBJECTIVE

Overexpression of zinc-alpha-2-glycoprotein (ZAG) can be induced by various factors and has potential to be a biomarker in certain malignancies. However, in oral squamous cell carcinoma (OSCC), the risks and effects associated with ZAG overexpression are still poorly known. Here, we investigated the effect of HPV16 oncogenes and arecoline on the expression levels of ZAG and the possible effects of ZAG in OSCC cell lines.

DESIGN

The level of ZAG expression was determined in protein extracted from exfoliated buccal cells from cancer-free control individuals and oral lesion cells from OSCC. Oral cell lines expressing HPV16E6/E7, and treated with arecoline were prepared to investigate ZAG expression. The effects of ZAG on cell biological activity and its targeting of UCP1 were determined in ZAG-overexpressing and ZAG-knockdown cells.

RESULTS

The expression of ZAG protein was significantly increased in oral lesion cells from OSCC relative to controls. Notably, the expression level of ZAG in OSCC positive for HPV, betel-quid chewing, and combination of both factors, was slightly higher than in cancer-free controls. ZAG expression was upregulated in oral cells treated with HPV16 oncoproteins E6 and/or E7, and treatment with arecoline (25 μg/ml). Interestingly, ZAG overexpression significantly increased UCP1 and decreased apoptosis, whereas decreased UCP1 and increased apoptosis were found in ZAG-knockdown cells. The mRNA expression levels of TP53, STAT3, BCL2, and NFKB1 corresponded to observed anti-apoptosis function.

CONCLUSIONS

HPV oncoproteins and high doses of arecoline are risk factors for an overexpressed ZAG protein that has an anti-apoptotic function in OSCC.

Metabolaging: a new geroscience perspective linking aging pathologies and metabolic dysfunction

With age, our metabolic systems undergo significant alterations, which can lead to a cascade of adverse effects that are implicated in both metabolic disorders, such as diabetes, and in the body's ability to respond to acute stress and trauma. To elucidate the metabolic imbalances arising from aging, we introduce the concept of "metabolaging." This framework encompasses the broad spectrum of metabolic disruptions associated with the hallmarks of aging, including the functional decline of key metabolically active organs, like the adipose tissue. By examining how these organs interact with essential nutrient-sensing pathways, "metabolaging" provides a more comprehensive view of the systemic metabolic imbalances that occur with age. This concept extends to understanding how age-related metabolic disturbances can influence the response to acute stressors, like burn injuries, highlighting the interplay between metabolic dysfunction and the ability to handle severe physiological challenges. Finally, we propose potential interventions that hold promise in mitigating the effects of metabolaging and its downstream consequences.

Subcutaneous adipose tissue [18F]FDG uptake and CT-derived body composition variables for predicting survival outcomes in patients with locally advanced gastric cancer

PURPOSE

This study aimed to investigate the impact of glucose metabolism in subcutaneous adipose tissue (SAT) and skeletal muscle (SM) variables on overall survival (OS) in patients with locally advanced gastric cancer.

METHODS

A retrospective study was conducted on 110 patients with advanced gastric cancer who underwent baseline [18F]FDG PET/CT. Demographic, clinical, and survival data were collected. Mean standardized uptake value (SUVmean) of SAT as well as skeletal muscle, and body composition measurement, including SAT area, SAT radiodensity, SM area, and SM radiodensity, were assessed on PET/CT. SM area was normalized for patient stature, resulting in the skeletal muscle index (SMI). Patients were stratified into subgroups with high and low SAT uptake based on the optimum cut-off value of the SAT SUVmean. The univariate, multivariate regression analysis, Kaplan-Meier survival analysis, and Spearman's correlation analysis were employed to evaluate the associations among metabolic activity and CT-derived body composition variables as well as OS.

RESULTS

Out of 110 patients with an average age of 62.65 ± 13.25 years, 58 (52.73%) patients died during follow-up. Cox regression analysis identified TNM stage, SAT SUVmean, and SMI as independent prognostic factors for OS (all p < 0.05). Notably, patients with elevated SAT uptake exhibited significantly poorer long-term survival compared to those with low SAT uptake (p < 0.001). Correlation analyses revealed a moderate positive association between SAT SUVmean and SAT radiodensity (p < 0.001, r = 0.47), whereas a significant inverse correlation was observed between SAT SUVmean and SAT area (p < 0.001, r = -0.465). Additionally, stratification by combined SAT SUVmean and SMI profiles showed that patients with low SAT uptake and high SMI exhibited a better prognosis than those with high SAT uptake and/or low SMI (p = 0.004 and p < 0.001).

CONCLUSION

Increased [18F]FDG uptake in SAT was correlated with higher SAT radiodensity as well as lower SAT area, and shortened survival in patients with advanced gastric cancer, underscoring its potential as a biomarker for adverse outcomes.

Cancer cachexia: exploring parallels with other paraneoplastic syndromes

PURPOSE OF REVIEW

Cancer cachexia (CC) is a paraneoplastic syndrome (PNS) that is characterised by anorexia, weight loss, fatigue and reduced function. This review explores the molecular drivers of CC and other PNS, identifying shared pathways and highlighting unexplored gaps in research.

RECENT FINDINGS

Recent studies have provided further evidence of pro-inflammatory cytokines, such as interleukin-6 and tumour necrosis factor-α, as central players in both CC and PNS, emphasising their role in systemic effects like muscle wasting, lipolysis and pyrexia. Despite these overlaps between syndromes, cytokine profiles vary across different cancer types with one study highlighting that the interplay between multiple cytokines likely plays a more significant role in cancer phenotypes than individual cytokines. Mediators, such as parathyroid hormone related peptide and vascular endothelial growth factor, which are typically associated with malignant hyperkalaemia and hypertrophic osteoarthropathy respectively, have also been linked to cachexia, suggesting a shared role.

SUMMARY

This review highlights the overlap between CC and other PNS. Exploring these shared mechanisms can bridge research gaps and improve CC treatment strategies. Similar insights may be gained by examining other conditions which overlap with CC such as eating disorders, bariatric surgery and sepsis.

The Influence of the Sympathetic Nervous System on Cardiometabolic Health in Response to Weight Gain or Weight Loss

Alterations in sympathetic nervous activity are evident in response to changes in body weight. Sympathetic nervous activity and sympathetic responses to weight change are regionalized, with alterations in end organ function dependent on the changes occurring in the brain regulatory pathways invoked and in the effector organs engaged. The obesity-induced activation of the sympathetic nervous system likely contributes to the initiation and worsening of cardiometabolic risk factors, including elevated blood pressure, cardiac dysfunction, dyslipidaemia, increased fasting blood glucose, insulin resistance, and non-alcoholic steatohepatitis. Unintended weight loss, as occurs in cachexia, is driven, at least in part, by the activation of sympathetic nervous-stimulated thermogenesis. The complexity of sympathetic nervous regulation renders the use of global measures of sympathetic activity problematic and the development of targeted therapies difficult, but these are not without promise or precedent. Knowledge of the central and peripheral pathways involved in sympathetic nervous regulation has opened up opportunities for pharmacological, surgical, and device-based approaches to mitigating the burden of disease development and progression. In this narrative review, we elaborate on sympathetic activity in response to changes in body weight, the brain pathways involved, and the cardiovascular and metabolic risks associated with perturbations in regional sympathetic activity.

Hallmarks of Cancer Cachexia: Sexual Dimorphism in Related Pathways

Cancer-associated cachexia (CAC), also known as wasting syndrome, is a systemic condition that affects multiple tissues and organs via a variety of metabolic pathways. Systemic inflammation, progressive weight loss, depletion of adipose tissue, and skeletal muscle impairment are some of the hallmark features of cachexia. Despite various studies on the clinical features of CAC, the complexity of the syndrome continues to pose significant challenges in clinical practice, leading to late diagnoses and the absence of a standardised treatment. Men and women respond differently to CAC, which may be prompted by the pre-existing physiologic sex differences. This review presents the sexual dimorphism associated with the hallmark pathways involved in CAC. A comprehensive understanding of sexual dimorphism in these pathways could drive research on cachexia to prioritise the inclusion of more females in related studies in order to achieve personalised sex-based therapeutic approaches and, consequently, enhance treatment efficacy and better patient outcomes.

TRIM22 governs tumorigenesis and protects against endometrial cancer-associated cachexia by inhibiting inflammatory response and adipose thermogenic activity

BACKGROUND

Endometrial cancer (EC) is one of the most common cancers in women, with a short overall survival and poor prognosis. Besides the biologically aggressive EC properties, Cancer-associated cachexia is the main factor. However, the detailed mechanism underlying EC-related cachexia and its harmful effects on EC progression and patient prognosis remains unclear.

METHODS

For clinical specimen and the vitro experiment, we detected TRIM22 expression level, EC patients' survival time, EC cell functional change, and adipose thermogenic changes to identify the function of TRIM22 in EC progression, EC-associated cachexia, and their molecular mechanisms. Then, for the vivo experiment, we exploited the xenografts in mice to identify the function of TRIM22 again, and to screen the drug therapeutic schedule.

RESULTS

Herein, we demonstrated that TRIM22 inhibited EC cell growth, invasion, and migration. Interleukin (IL)-6 mediated brown adipose tissue activation and white adipose tissue browning which induced EC-related cachexia. TRIM22 suppressed the EC cells' secretion of IL-6, and IL-6 mediated EC-related cachexia. Mechanistically, TRIM22 inhibited EC progression by suppressing the nucleotide-binding oligomerization domain 2(NOD2)/nuclear factor-kappaB (NF-κB) signaling pathway, with the purpose of impeding the production of IL-6. Moreover, we revealed that TRIM22 inhibited EC-associated cachexia by suppressing the IL-6/IL-6 receptor (IL-6R) signaling pathway. Therapeutically, we demonstrated that combination treatment with a TRIM22 inducer (progesterone) and a thermogenic inhibitor (IL-6R antibody) synergistically augmented the antitumor efficacy of carbotaxol (carboplatin and paclitaxel), in vivo.

CONCLUSION

Our data reveals that TRIM22-EC-IL-6-cachexia cross-communication has important clinical relevance and that the use of combined therapy holds great promise for enhancing the efficacy of anti-ECs. (Fig. graphical abstract).

MIF-ACKR3 causes irreversible fat loss by impairing adipogenesis in cancer cachexia

Both exercise and cancer can cause adipose tissue shrinkage. However, only cancer-associated weight loss, namely cachexia, is characterized by profound adipose inflammation and fibrosis. Here, we identified tumor-secreted macrophage migration inhibitory factor (MIF) as a major driver that skews the differentiation of adipose stem and progenitor cells (ASPCs) toward a pro-inflammatory and pro-fibrogenic direction, with reduced adipogenic capacity in cancer cachexia. By contrast, circulating MIF is moderately reduced after exercise. Mechanistically, atypical chemokine receptor 3 (ACKR3) in ASPCs serves as the predominant MIF receptor mediating its pathological effects. Inhibition of MIF by gene ablation in tumor cells or pharmacological blockade, as well as ASPC-specific Ackr3 deficiency, markedly alleviates tumor-induced cachexia. These findings unveil MIF-ACKR3 signaling as a critical link between tumors and cachectic manifestations, providing a promising therapeutic target for cancer cachexia.

Polygonatum cyrtonema Hua polysaccharides alleviate muscle atrophy and fat lipolysis by regulating the gut microenvironment in chemotherapy-induced cachexia

Introduction: Polygonatum cyrtonema Hua (PC) is an essential herbal medicine in China, known for improving muscle quality and enhancing physical function; its active ingredients are polysaccharides (PCPs). A previous study revealed the anti-atrophy effects of PCPs in cachectic mice. However, whether the effects of PCPs on anti-atrophy are associated with gut microenvironment remain elusive. This research endeavored to assess the medicinal efficacy of PCPs in alleviating muscle atrophy and fat lipolysis and explore the potential mechanisms. Methods: A cancer cachexia model was induced by male C57BL/6 mice bearing Lewis lung tumor cells and chemotherapy. The pharmacodynamics of PCPs (32 and 64 mg/kg/day) was investigated through measurements of tumor-free body weight, gastrocnemius muscle weight, soleus muscle weight, epididymal fat weight, tissue histology analysis, and pro-inflammatory cytokines. Immunohistochemistry and Western blotting assays were further used to confirm the effects of PCPs. 16S rRNA sequencing, LC-MS and GC-MS-based metabolomics were used to analyze the gut microbiota composition and metabolite alterations. Additionally, the agonist of free fatty acid receptor 2 (FFAR2)-a crucial short-chain fatty acid (SCFA) signaling molecule-was used to investigate the role of gut microbiota metabolites, specifically SCFAs, in the treatment of cancer cachexia, with comparisons to PCPs. Results: This study demonstrated that PCPs significantly mitigated body weight loss, restored muscle fiber atrophy and mitochondrial disorder, alleviated adipose tissue wasting, strengthened the intestinal barrier integrity, and decreased the intestinal inflammation in chemotherapy-induced cachexia. Furthermore, the reversal of specific bacterial taxa including Klebsiella, Akkermansia, norank_f__Desulfovibrionaceae, Enterococcus, NK4A214_group, Eubacterium_fissicatena_group, Eubacterium_nodatum_group, Erysipelatoclostridium, Lactobacillus, Monoglobus, Ruminococcus, Odoribacter, and Enterorhabdus, along with alterations in metabolites such as amino acids (AAs), eicosanoids, lactic acid and (SCFAs), contributed to the therapeutic effects of PCPs. Conclusion: Our findings suggest that PCPs can be used as prebiotic drugs targeting the microbiome-metabolomics axis in cancer patients undergoing chemotherapy.

Interaction between chronic kidney disease and atrial fibrillation on incident stroke and all-cause mortality: Matched cohort study of 49,594 patients

BACKGROUND AND AIMS

The interaction between full-spectrum chronic kidney disease (CKD) and atrial fibrillation (AF) on ischemic stroke and all-cause mortality risk, particularly in stage 4 and 5 CKD, remains undetermined.

METHODS

This matched cohort study identified incident AF patients using the International Classification of Disease codes and electrocardiograms from the Clinical Research Data Repository of China Medical University Hospital between 2003 and 2020. For each AF patient, we selected four controls without AF and matched them by age, sex, eGFR within 10 mL/min/1.73 m2, end-stage kidney disease (ESKD) vintage, and diagnosis year. Multivariable Cox proportional hazard models were utilized to assess the interaction between AF and CKD on three-year ischemic stroke and all-cause mortality outcomes.

RESULTS

Within a total of 10,155 patients and 39,439 controls, incidence rates were 3.03 % and 1.48 % for ischemic stroke and 15.6 % and 9.53 % for overall mortality, respectively. In AF, the stroke risk was the highest among patients with stage 4 and 5-ND (non-dialysis) CKD with adjusted hazard ratio (aHR) of 3.31 (95 % CI, 2.46-4.45) and 2.73 (1.88-3.96), respectively. The mortality risk difference varied between 45% and 177 % with the highest difference noted in ESKD (aHR 3.36 [95 % CI, 2.84-3.98] in AF vs. 1.59 [95 % CI, 1.28-1.96] in non-AF; interaction p < 0.001). Anticoagulation therapy significantly lowered the mortality risk among patients with AF and advanced CKD (3-way interaction p < 0.001).

CONCLUSIONS

The risk of ischemic stroke and overall mortality was particularly high among patients with concurrent AF and stage 4 and 5-ND CKD, underscoring the urgent evidence to optimize prognosis.

Brown adipose tissue is associated with reduced weight loss and risk of cancer cachexia: A retrospective cohort study

BACKGROUND & AIMS

Brown adipose tissue (BAT) has been mainly investigated as a potential target against cardiometabolic disease, but it has also been linked to cancer-related outcomes. Although preclinical data support that BAT and the thermogenic adipocytes in white adipose tissue may play an adverse role in the pathogenesis of cancer cachexia, results from studies in patients have reported inconsistent results. The purpose of this study was to examine the interrelationship between presence of detectable BAT, changes in body weight, and cachexia in patients with cancer. We hypothesized that evidence of BAT at cancer diagnosis would be associated with greater weight loss and risk of cancer cachexia up to a year after cancer diagnosis.

METHODS

We conducted a retrospective cohort study in treatment-naïve patients with detectable BAT (BAT+, n = 57) and without evidence of BAT (BAT-, n = 73) on 2-deoxy-2-[18F]fluoro-d-glucose positron emission tomography-computed tomography (18F-FDG-PET-CT) imaging performed for cancer staging (2004-2020). Patients' clinical, demographic, and anthropometric characteristics were extracted from their electronic medical record for up to a year after diagnosis. The two groups were a priori matched for demographic, anthropometric, and disease-related characteristics at diagnosis, as well as for season and outdoor temperature on the day of the PET-CT scan. Cancer cachexia was defined as weight loss greater than 5 % or 2 % if body mass index was lower than 20 kg/m2. Poisson regression models were fitted to estimate the relative risk (RR) for developing cancer cachexia over the 1-year follow-up among BAT+ compared to BAT- patients.

RESULTS

The BAT+ group experienced a lower magnitude of weight loss compared with the BAT- group during the 1-year follow-up (p = 0.014 for interaction between BAT status and time). The risk for cancer cachexia was 44 % lower in the BAT+ than the BAT- group, adjusted for age, sex, outdoor temperature on the day of the 18F-FDG-PET-CT imaging, cancer site and stage (RR: 0.56, 95 % CI: 0.32 to 0.97).

CONCLUSION

Contrary to our original hypothesis, evidence of BAT assessed by 18F-FDG-PET-CT imaging at cancer diagnosis was associated with greater body weight maintenance and lower risk for developing cancer cachexia up to one year after diagnosis. Larger, prospective studies and mechanistic experiments are needed to expand and identify the causal factors of our observations.

Mechanisms and pharmacotherapy of cancer cachexia-associated anorexia

Cachexia is a multifactorial metabolic syndrome characterized by weight and skeletal muscle loss caused by underlying illnesses such as cancer, heart failure, and renal failure. Inflammation, insulin resistance, increased muscle protein degradation, decreased food intake, and anorexia are the primary pathophysiological drivers of cachexia. Cachexia causes physical deterioration and functional impairment, loss of quality of life, lower response to active treatment, and ultimately morbidity and mortality, while the difficulties in tackling cachexia in its advanced phases and the heterogeneity of the syndrome among patients require an individualized and multidisciplinary approach from an early stage. Specifically, strategies combining nutritional and exercise interventions as well as pharmacotherapy that directly affect the pathogenesis of cachexia, such as anti-inflammatory, metabolism-improving, and appetite-stimulating agents, have been proposed, but none of which have demonstrated sufficient evidence to date. Nevertheless, several agents have recently emerged, including anamorelin, a ghrelin receptor agonist, growth differentiation factor 15 neutralization therapy, and melanocortin receptor antagonist, as candidates for ameliorating anorexia associated with cancer cachexia. Therefore, in this review, we outline cancer cachexia-associated anorexia and its pharmacotherapy, including corticosteroids, progesterone analogs, cannabinoids, anti-psychotics, and thalidomide which have been previously explored for their efficacy, in addition to the aforementioned novel agents, along with their mechanisms.

GDF15-GFRAL signaling drives weight loss and lipid metabolism in mouse model of amyotrophic lateral sclerosis

Weight loss is a common early sign in amyotrophic lateral sclerosis (ALS) patients and negatively correlates with survival. In different cancers and metabolic disorders, high levels of serum growth differentiation factor 15 (GDF15) contribute to a decrease of food intake and body weight, acting through GDNF family receptor alpha-like (GFRAL). Here we report that GDF15 is highly expressed in the peripheral blood of ALS patients and in the hSOD1G93A mouse model and that GFRAL is upregulated in the brainstem of hSOD1G93A mice. We demonstrate that the localized GFRAL silencing by shRNA in the area postrema/nucleus tractus solitarius of hSOD1G93A mice induces weight gain, reduces adipose tissue wasting, ameliorates the motor function and muscle atrophy and prolongs the survival time. We report that microglial cells could be involved in mediating these effects because their depletion with PLX5622 reduces brainstem GDF15 expression, weight loss and the expression of lipolytic genes in adipose tissue. Altogether these results reveal a key role of GDF15-GFRAL signaling in regulating weight loss and the alteration of and lipid metabolism in the early phases of ALS.

Mitochondrial respiration in white adipose tissue is dependent on body mass index and tissue location in patients undergoing oncological or parietal digestive surgery

Adipose tissue (AT), is a major endocrine organ that plays a key role in health and disease. However, adipose dysfunctions, especially altered energy metabolism, have been under-investigated as white adipocytes have relatively low mitochondrial density. Nevertheless, recent studies suggest that mitochondria could play a major role in AT disorders and that AT mitochondrial activity could depend on adiposity level and location. This clinical study aimed to evaluate mitochondrial respiration and metabolism in human visceral (vAT) and subcutaneous (scAT) AT and their relationship with body mass index (BMI). This clinical study enrolled 67 patients (30 females/37 males) scheduled for digestive surgery without chemotherapy and parietal infection. BMI ranged from 15.4 to 51.9 kg·m-2 and body composition was estimated by computed tomographic images. Mitochondrial respiration was measured in situ in digitonin-permeabilized AT using high-resolution respirometry and a substrate/inhibitor titration approach. Protein levels of mitochondrial and lipid metabolism key elements were evaluated by Western blot. Maximal mitochondrial respiration correlated negatively with BMI (p < .01) and AT area (p < .001) regardless of the anatomical location. However, oxidative phosphorylation respiration was significantly higher in vAT (2.22 ± 0.15 pmol·sec-1·mg-1) than scAT (1.79 ± 0.17 pmol·sec-1·mg-1) (p < 0.001). In line with oxygraphy results, there were higher levels of mitochondrial respiratory chain complexes in low-BMI patients and vAT. Mitochondrial respiration decreased with increasing BMI in both scAT and vAT, without sex-associated difference. Mitochondrial respiration appeared to be higher in vAT than scAT. These differences were both qualitative and quantitative. Clinical Trials Registration IDNCT05417581.

Unraveling the peripheral nervous System's role in tumor: A Double-edged Sword

The peripheral nervous system (PNS) includes all nerves outside the brain and spinal cord, comprising various cells like neurons and glial cells, such as schwann and satellite cells. The PNS is increasingly recognized for its bidirectional interactions with tumors, exhibiting both pro- and anti-tumor effects. Our review delves into the complex mechanisms underlying these interactions, highlighting recent findings that challenge the conventional understanding of PNS's role in tumorigenesis. We emphasize the contradictory results in the literature and propose novel perspectives on how these discrepancies can be resolved. By focusing on the PNS's influence on tumor initiation, progression, and microenvironment remodeling, we provide a comprehensive analysis that goes beyond the structural description of the PNS. Our review suggests that a deeper comprehension of the PNS-tumor crosstalk is pivotal for developing targeted anticancer strategies. We conclude by emphasizing the need for future research to unravel the intricate dynamics of the PNS in cancer, which may lead to innovative diagnostic tools and therapeutic approaches.

Dietary caloric input and tumor growth accelerate senescence and modulate liver and adipose tissue crosstalk

Metabolic alterations are related to tumorigenesis and other age-related diseases that are accelerated by "Westernized" diets. In fact, hypercaloric nutrition is associated with an increased incidence of cancers and faster aging. Conversely, lifespan-extending strategies, such as caloric restriction, impose beneficial effects on both processes. Here, we investigated the metabolic consequences of hypercaloric-induced aging on tumor growth in female mice. Our findings indicate that a high-fat high-sucrose diet increases tumor growth mainly due to the boosted oxidation of glucose and fatty acids. Consequently, through an increased expression of lactate, IGFBP3, and PTHLH, tumors modulate liver and white adipose tissue metabolism. In the liver, the induced tumor increases fibrosis and accelerates the senescence process, despite the lower systemic pro-inflammatory state. Importantly, the induced tumor induces the wasting and browning of white adipose tissue, thereby reversing diet-induced insulin resistance. Finally, we suggest that tumor growth alters liver-adipose tissue crosstalk that upregulates Fgf21, induces senescence, and negatively modulates lipids and carbohydrates metabolism even in caloric-restricted-fed mice.

Emerging debates and resolutions in brown adipose tissue research

Until two decades ago, brown adipose tissue (BAT) was studied primarily as a thermogenic organ of small rodents in the context of cold adaptation. The discovery of functional human BAT has opened new opportunities to understand its physiological role in energy balance and therapeutic applications for metabolic disorders. Significantly, the role of BAT extends far beyond thermogenesis, including glucose and lipid homeostasis, by releasing mediators that communicate with other cells and organs. The field has made major advances by using new model systems, ranging from subcellular studies to clinical trials, which have also led to debates. In this perspective, we identify six fundamental issues that are currently controversial and comprise dichotomous models. Each side presents supporting evidence and, critically, the necessary methods and falsifiable experiments that would resolve the dispute. With this collaborative approach, the field will continue to productively advance the understanding of BAT physiology, appreciate the importance of thermogenic adipocytes as a central area of ongoing research, and realize the therapeutic potential.

Sarcopenia and cachexia: molecular mechanisms and therapeutic interventions

Sarcopenia is defined as a muscle-wasting syndrome that occurs with accelerated aging, while cachexia is a severe wasting syndrome associated with conditions such as cancer and immunodeficiency disorders, which cannot be fully addressed through conventional nutritional supplementation. Sarcopenia can be considered a component of cachexia, with the bidirectional interplay between adipose tissue and skeletal muscle potentially serving as a molecular mechanism for both conditions. However, the underlying mechanisms differ. Recognizing the interplay and distinctions between these disorders is essential for advancing both basic and translational research in this area, enhancing diagnostic accuracy and ultimately achieving effective therapeutic solutions for affected patients. This review discusses the muscle microenvironment's changes contributing to these conditions, recent therapeutic approaches like lifestyle modifications, small molecules, and nutritional interventions, and emerging strategies such as gene editing, stem cell therapy, and gut microbiome modulation. We also address the challenges and opportunities of multimodal interventions, aiming to provide insights into the pathogenesis and molecular mechanisms of sarcopenia and cachexia, ultimately aiding in innovative strategy development and improved treatments.

Cancer knocks you out by fasting: Cachexia as a consequence of metabolic alterations in cancer

Neoplastic transformation reprograms tumor and surrounding host cell metabolism, increasing nutrient consumption and depletion in the tumor microenvironment. Tumors uptake nutrients from neighboring normal tissues or the bloodstream to meet energy and anabolic demands. Tumor-induced chronic inflammation, a high-energy process, also consumes nutrients to sustain its dysfunctional activities. These tumor-related metabolic and physiological changes, including chronic inflammation, negatively impact systemic metabolism and physiology. Furthermore, the adverse effects of antitumor therapy and tumor obstruction impair the endocrine, neural, and gastrointestinal systems, thereby confounding the systemic status of patients. These alterations result in decreased appetite, impaired nutrient absorption, inflammation, and shift from anabolic to catabolic metabolism. Consequently, cancer patients often suffer from malnutrition, which worsens prognosis and increases susceptibility to secondary adverse events. This review explores how neoplastic transformation affects tumor and microenvironment metabolism and inflammation, leading to poor prognosis, and discusses potential strategies and clinical interventions to improve patient outcomes.

The RNA-binding protein HuR impairs adipose tissue anabolism in pancreatic cancer cachexia

Background

Cachexia is defined by chronic loss of fat and muscle, is a frequent complication of pancreatic ductal adenocarcinoma (PDAC), and negatively impacts patient outcomes. Nutritional supplementation cannot fully reverse tissue wasting, and the mechanisms underlying this phenotype are unclear. This work aims to define the relative contributions of catabolism and anabolism to adipose wasting in PDAC-bearing mice. Human antigen R (HuR) is an RNA-binding protein recently shown to suppress adipogenesis. We hypothesize that fat wasting results from a loss of adipose anabolism driven by increased HuR activity in adipocytes of PDAC-bearing mice.

Methods

Adult C57BL/6J mice received orthotopic PDAC cell (Kras G12D ; p53 R172H/+ ; Pdx1-cre) (OT-PDAC) or PBS (sham) injections. Mice exhibiting moderate cachexia (9 days after injection) were fasted for 24h, or fasted 24h and refed 24h before euthanasia. A separate cohort of PDAC mice were treated with an established HuR inhibitor (KH-3, 100 mg/kg) and subjected to the fast/refeed paradigm. We analyzed body mass, gross fat pad mass, and adipose tissue mRNA expression. We quantified lipolytic rate as the normalized quantity of glycerol released from 3T3-L1 adipocytes in vitro, and gonadal fat pads (gWAT) ex vivo.

Results

3T3-L1 adipocytes treated with PDAC cell conditioned media (CM) liberated less triglyceride into the culture media than control-treated adipocytes (-28.1%) and had lower expression of lipolysis and lipogenesis genes than control cells. PDAC gWAT cultured ex vivo displayed decreased lipolysis compared to sham gWAT (-54.7%). PDAC and sham mice lost equivalent fat mass after a 24h fast, however, PDAC mice could not restore inguinal fat pads (iWAT) (-40.5%) or gWAT (-31.8%) mass after refeeding. RNAseq revealed 572 differentially expressed genes in gWAT from PDAC compared to sham mice. Downregulated genes (n=126) were associated with adipogenesis (adj p=0.05), and expression of adipogenesis master regulators Pparg and Cebpa were reduced in gWAT from PDAC mice. Immunohistochemistry revealed increased HuR staining in gWAT (+74.9%) and iWAT (+41.2%) from PDAC mice. Inhibiting HuR binding restored lipogenesis in refed animals with a concomitant increase in iWAT mass (+131.7%) and genes regulating adipogenesis (Pparγ, Cebpa, Retn, Adipoq, Fasn).

Conclusions

Our work highlights deficient adipose anabolism as a driver of wasting in 3T3-L1 adipocytes treated with PDAC conditioned media and OT-PDAC mice. The small molecule KH3, which disrupts HuR binding, was sufficient to restore adipogenic and lipogenic gene expression and prevent adipose wasting. This highlights HuR as a potentially targetable regulatory node for adipose anabolism in cancer cachexia.

Neurobiology of cancer: Adrenergic signaling and drug repurposing

Cancer neuroscience, as an emerging converging discipline, provides us with new perspectives on the interactions between the nervous system and cancer progression. As the sympathetic nervous system, in particular adrenergic signaling, plays an important role in the regulation of tumor activity at every hierarchical level of life, from the tumor cell to the tumor microenvironment, and to the tumor macroenvironment, it is highly desirable to dissect its effects. Considering the far-reaching implications of drug repurposing for antitumor drug development, such a large number of adrenergic receptor antagonists on the market has great potential as one of the means of antitumor therapy, either as primary or adjuvant therapy. Therefore, this review aims to summarize the impact of adrenergic signaling on cancer development and to assess the status and prospects of intervening in adrenergic signaling as a therapeutic tool against tumors.

Cancer cachexia: multilevel metabolic dysfunction

Cancer cachexia is a complex metabolic disorder marked by unintentional body weight loss or 'wasting' of body mass, driven by multiple aetiological factors operating at various levels. It is associated with many malignancies and significantly contributes to cancer-related morbidity and mortality. With emerging recognition of cancer as a systemic disease, there is increasing awareness that understanding and treatment of cancer cachexia may represent a crucial cornerstone for improved management of cancer. Here, we describe the metabolic changes contributing to body wasting in cachexia and explain how the entangled action of both tumour-derived and host-amplified processes induces these metabolic changes. We discuss energy homeostasis and possible ways that the presence of a tumour interferes with or hijacks physiological energy conservation pathways. In that context, we highlight the role played by metabolic cross-talk mechanisms in cachexia pathogenesis. Lastly, we elaborate on the challenges and opportunities in the treatment of this devastating paraneoplastic phenomenon that arise from the complex and multifaceted metabolic cross-talk mechanisms and provide a status on current and emerging therapeutic approaches.

Rheumatic diseases and metabolism: where centre and periphery meet

Over the past few decades, the connection between metabolism and various inflammatory and rheumatic diseases has been an area of active investigation. Nonetheless, the precise mechanisms underlying these relationships remain a topic of ongoing debate, owing in part to conflicting data. This discrepancy can be attributed to the predominant focus on peripheral mechanisms in research into the metabolic consequences of rheumatic diseases. However, a wealth of evidence supports the notion that the central nervous system, specifically the hypothalamus, has an important influence on metabolic homeostasis. Notably, links have been established between crucial hypothalamic mechanisms responsible for regulating energy balance (including food intake, thermogenesis, and glucose and lipid metabolism), such as AMP-activated protein kinase, and the pathophysiology of rheumatoid arthritis. This Review aims to comprehensively examine the current understanding of central metabolic control in rheumatic diseases and explore potential therapeutic options that target this pathophysiological mechanism.

Early adipose tissue wasting in a novel preclinical model of human lung cancer cachexia

Cancer cachexia (CC), a syndrome of skeletal muscle and adipose tissue wasting, reduces responsiveness to therapies and increases mortality. There are no approved treatments for CC, which may relate to discordance between pre-clinical models and human CC. To address the need for clinically relevant models, we generated tamoxifen-inducible, epithelial cell specific Kras G12D/+ ( G12D ) mice. G12D mice develop CC over a protracted time course and phenocopy tissue, cellular, mutational, transcriptomic, and metabolic characteristics of human lung CC. CC in G12D mice is characterized by early loss of adipose tissue, a phenotype confirmed in a large cohort of patients with lung cancer. Tumor-released factors promote adipocyte lipolysis, a driver of adipose wasting in human CC, and adipose tissue wasting was inversely related to tumor burden. Thus, G12D mice model key features of human lung CC and suggest a novel role for early adipose tissue wasting in CC.

Characterization of a Cancer-Induced Bone Pain Model for Use as a Model of Cancer Cachexia

Cancer cachexia is a debilitating syndrome characterized by progressive weight loss, muscle wasting, and systemic inflammation. Despite the prevalence and severe consequences of cancer cachexia, effective treatments for this syndrome remain elusive. Therefore, there is a greater need for well-characterized animal models to identify novel therapeutic targets. Certain manifestations of cachexia, such as pain and depression, have been extensively studied using animal models of cancer-induced bone pain (CIBP). In contrast, other aspects of cachexia have received less attention in these models. To address this issue, we established the CIBP model by injecting Lewis lung carcinoma into the intramedullary cavity of the femur, observed cachexia-related symptoms, and demonstrated the utility of this model as a preclinical platform to study cancer cachexia. This model accurately recapitulates key features of cancer cachexia, including weight loss, muscle atrophy, adipose tissue depletion, CIBP, and anxiety. These findings suggest that psychological factors, in addition to physiological and metabolic factors, play significant roles in cancer cachexia development. Our model offers a valuable resource for investigating the underlying mechanisms of cancer cachexia and for developing innovative therapeutic strategies that target physical and psychological components.

Hyperactive browning and hypermetabolism: potentially dangerous element in critical illness

Brown/beige adipose tissue has attracted much attention in previous studies because it can improve metabolism and combat obesity through non-shivering thermogenesis. However, recent studies have also indicated that especially in critical illness, overactivated brown adipose tissue or extensive browning of white adipose tissue may bring damage to individuals mainly by exacerbating hypermetabolism. In this review, the phenomenon of fat browning in critical illness will be discussed, along with the potential harm, possible regulatory mechanism and corresponding clinical treatment options of the induction of fat browning. The current research on fat browning in critical illness will offer more comprehensive understanding of its biological characteristics, and inspire researchers to develop new complementary treatments for the hypermetabolic state that occurs in critically ill patients.

Energy Landscape Reveals the Underlying Mechanism of Cancer-Adipose Conversion in Gene Network Models

Cancer is a systemic heterogeneous disease involving complex molecular networks. Tumor formation involves an epithelial-mesenchymal transition (EMT), which promotes both metastasis and plasticity of cancer cells. Recent experiments have proposed that cancer cells can be transformed into adipocytes via a combination of drugs. However, the underlying mechanisms for how these drugs work, from a molecular network perspective, remain elusive. To reveal the mechanism of cancer-adipose conversion (CAC), this study adopts a systems biology approach by combing mathematical modeling and molecular experiments, based on underlying molecular regulatory networks. Four types of attractors are identified, corresponding to epithelial (E), mesenchymal (M), adipose (A) and partial/intermediate EMT (P) cell states on the CAC landscape. Landscape and transition path results illustrate that intermediate states play critical roles in the cancer to adipose transition. Through a landscape control approach, two new therapeutic strategies for drug combinations are identified, that promote CAC. These predictions are verified by molecular experiments in different cell lines. The combined computational and experimental approach provides a powerful tool to explore molecular mechanisms for cell fate transitions in cancer networks. The results reveal underlying mechanisms of intermediate cell states that govern the CAC, and identified new potential drug combinations to induce cancer adipogenesis.

Mechanisms of cancer cachexia and targeted therapeutic strategies

Tumor cachexia is a multifactorial syndrome characterized by systemic dysfunction, including anorexia and severe weight loss that is resistant to standard nutritional interventions. It is estimated that approximately 20 % of cancer patients succumb to cachexia in the later stages of their disease. Thus, understanding its pathogenesis is vital for improving therapeutic outcomes. Recent research has focused on the imbalance between energy intake and expenditure in cachexia. Clinically, cachexia presents with anorexia, adipose tissue atrophy, and skeletal muscle wasting, each driven by distinct mechanisms. Anorexia arises primarily from tumor-secreted factors and cancer-induced hormonal disruptions that impair hypothalamic regulation of appetite. Adipose tissue atrophy is largely attributed to enhanced lipolysis, driven by increased activity of enzymes such as adipose triglyceride lipase and hormone-sensitive lipase, coupled with decreased lipoprotein lipase activity. The browning of white adipose tissue, facilitated by uncoupling protein 1, further accelerates fat breakdown by increasing energy expenditure. Skeletal muscle atrophy, a hallmark of cachexia, results from dysregulated protein turnover via the ubiquitin-proteasome and autophagy-lysosomal pathways, as well as mitochondrial dysfunction. Additionally, chemotherapy can exacerbate cachexia. This review examines the molecular mechanisms underlying cancer cachexia and discusses current therapeutic strategies, aiming to inform future research and improve treatment approaches.

A comprehensive review of animal models for cancer cachexia: Implications for translational research

Cancer cachexia is a multifactorial syndrome characterized by progressive weight loss and a disease process that nutritional support cannot reverse. Although progress has been made in preclinical research, there is still a long way to go in translating research findings into clinical practice. One of the main reasons for this is that existing preclinical models do not fully replicate the conditions seen in clinical patients. Therefore, it is important to understand the characteristics of existing preclinical models of cancer cachexia and pay close attention to the latest developments in preclinical models. The main models of cancer cachexia used in current research are allogeneic and xenograft models, genetically engineered mouse models, chemotherapy drug-induced models, Chinese medicine spleen deficiency models, zebrafish and Drosophila models, and cellular models. This review aims to revisit and summarize the commonly used animal models of cancer cachexia by evaluating existing preclinical models, to provide tools and support for translational medicine research.

Chemotherapy effects on mitochondrial function in adipose tissue in oesophageal and gastroesophageal junction adenocarcinomas with or without associated cachexia: protocol for a prospective, comparative observational study (ChiFMeOE)

INTRODUCTION

Cachexia is strongly associated with digestive cancers, particularly oesogastric cancer. Mitochondria in adipose tissue are involved in the regulation of metabolism and physiopathology of cancer cachexia in animal studies. Chemotherapeutic regimens used to control tumour development could also alter mitochondrial function in adipose tissue. We hypothesise that cachexia induces an increase in adipose tissue mitochondrial energy metabolism and that chemotherapy can mitigate this. The purpose of the ChiFMeOE study is to identify adipocyte factors involved in the energy imbalance associated with the cachectic process and their response to chemotherapeutic treatments in patients with oesogastric cancer.

METHODS AND ANALYSIS

ChiFMeOE is a single-centre observational study that will prospectively include 60 patients referred to chemotherapy and surgery for oesophageal and gastro-oesophageal junction adenocarcinomas at the University Hospital of Clermont-Ferrand, France. Visceral and subcutaneous adipose tissue biopsies will be collected during surgery scheduled before and after neoadjuvant chemotherapy administration, as well as cachexia and nutritional assessment. The primary outcome is the maximum mitochondrial respiration rate (Vmax) measured by high-resolution respirometry. Secondary outcomes are other mitochondrial parameters (ie, enzymatic activities, proteins content and gene expression), tumour characteristics, nutritional status and body composition.

ETHICS AND DISSEMINATION

The study was approved by an independent institutional review board on June 2023 (Comité de protection des personnes Sud-Méditerranée V; 2023-A00582-43) and declared to the French regulatory authority for research. Written informed consent will be obtained prior to patient inclusion. The principal investigator will be notified of any changes in patient's health status requiring a modification of his management and/or treatment during the course of the protocol. Results will be published in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov, NCT05954117.

β-Adrenergic blockade attenuates adverse adipose tissue responses after burn

Severe burn injuries are defined by a prolonged hypermetabolic response characterized by increases in resting energy expenditure, systemic catabolism, and multi-organ dysfunction. The sustained elevation of catecholamines following a burn injury is thought to significantly contribute to this hypermetabolic response, leading to changes in adipose tissue such as increased lipolysis and the browning of subcutaneous white adipose tissue (WAT). Failure to mitigate these adverse changes within the adipose tissue has been shown to exacerbate the post-burn hypermetabolic response and lead to negative outcomes. Propranolol, a non-selective β-blocker, has been clinically administered to improve outcomes of pediatric and adult burn patients, but there is inadequate knowledge of its effects on the distinct adipose tissue depots. In this study, we investigated the adipose depot-specific alterations that occur in response to burn injury. Moreover, we explored the therapeutic effects of β-adrenoceptor blockade via the drug propranolol in attenuating these burn-induced pathophysiological changes within the different fat depots. Using a murine model of thermal injury, we show that burn injury induces endoplasmic reticulum (ER) stress in the epididymal (eWAT) but not in the inguinal (iWAT) WAT depot. Conversely, burn injury induces the activation of key lipolytic pathways in both eWAT and iWAT depots. Treatment of burn mice with propranolol effectively mitigated adverse burn-induced alterations in the adipose by alleviating ER stress in the eWAT and reducing lipolysis in both depots. Furthermore, propranolol treatment in post-burn mice attenuated UCP1-mediated subcutaneous WAT browning following injury. Overall, our findings suggest that propranolol serves as an effective therapeutic intervention to mitigate the adverse changes induced by burn injury, including ER stress, lipotoxicity, and WAT browning, in both adipose tissue depots. KEY MESSAGES: Burn injury adversely affects adipose tissue metabolism via distinct changes in both visceral and subcutaneous adipose depots. Propranolol, a non-selective β-adrenergic blocker, attenuates many of the adverse adipose tissue changes mediated by burn injury.

Systemic Metabolic and Volumetric Assessment via Whole-Body [18F]FDG-PET/CT: Pancreas Size Predicts Cachexia in Head and Neck Squamous Cell Carcinoma

Background/Objectives: Cancer-associated cachexia in head and neck squamous cell carcinoma (HNSCC) is challenging to diagnose due to its complex pathophysiology. This study aimed to identify metabolic biomarkers linked to cachexia and survival in HNSCC patients using [18F]FDG-PET/CT imaging and machine learning (ML) techniques. Methods: We retrospectively analyzed 253 HNSCC patients from Vienna General Hospital and the MD Anderson Cancer Center. Automated organ segmentation was employed to quantify metabolic and volumetric data from [18F]FDG-PET/CT scans across 29 tissues and organs. Patients were categorized into low weight loss (LoWL; grades 0-2) and high weight loss (HiWL; grades 3-4) groups, according to the weight loss grading system (WLGS). Machine learning models, combined with Cox regression, were used to identify survival predictors. Shapley additive explanation (SHAP) analysis was conducted to determine the significance of individual features. Results: The HiWL group exhibited increased glucose metabolism in skeletal muscle and adipose tissue (p = 0.01), while the LoWL group showed higher lung metabolism. The one-year survival rate was 84.1% in the LoWL group compared to 69.2% in the HiWL group (p < 0.01). Pancreatic volume emerged as a key biomarker associated with cachexia, with the ML model achieving an AUC of 0.79 (95% CI: 0.77-0.80) and an accuracy of 0.82 (95% CI: 0.81-0.83). Multivariate Cox regression confirmed pancreatic volume as an independent prognostic factor (HR: 0.66, 95% CI: 0.46-0.95; p < 0.05). Conclusions: The integration of metabolic and volumetric data provided a strong predictive model, highlighting pancreatic volume as a key imaging biomarker in the metabolic assessment of cachexia in HNSCC. This finding enhances our understanding and may improve prognostic evaluations and therapeutic strategies.

GRP75 triggers white adipose tissue browning to promote cancer-associated cachexia

Cachexia, which affects 50-80% of cancer patients, is a debilitating syndrome that leads to 20% of cancer-related deaths. A key feature of cachexia is adipose tissue atrophy, but how it contributes to the development of cachexia is poorly understood. Here, we demonstrate in mouse models of cancer cachexia that white adipose tissue browning, which can be a characteristic early-onset manifestation, occurs prior to the loss of body weight and skeletal muscle wasting. By analysing the proteins differentially expressed in extracellular vesicles derived from cachexia-inducing tumours, we identified a molecular chaperone, Glucose-regulated protein 75 (GRP75), as a critical mediator of adipocyte browning. Mechanistically, GRP75 binds adenine nucleotide translocase 2 (ANT2) to form a GRP75-ANT2 complex. Strikingly, stabilized ANT2 enhances its interaction with uncoupling protein 1, leading to elevated expression of the latter, which, in turn, promotes adipocyte browning. Treatment with withanone, a GRP75 inhibitor, can reverse this browning and alleviate cachectic phenotypes in vivo. Overall, our findings reveal a novel mechanism by which tumour-derived GRP75 regulates white adipose tissue browning during cachexia development and suggest a potential white adipose tissue-centred targeting approach for early cachexia intervention.

IL36G-producing neutrophil-like monocytes promote cachexia in cancer

Most patients with advanced cancer develop cachexia, a multifactorial syndrome characterized by progressive skeletal muscle wasting. Despite its catastrophic impact on survival, the critical mediators responsible for cancer cachexia development remain poorly defined. Here, we show that a distinct subset of neutrophil-like monocytes, which we term cachexia-inducible monocytes (CiMs), emerges in the advanced cancer milieu and promotes skeletal muscle loss. Unbiased transcriptome analysis reveals that interleukin 36 gamma (IL36G)-producing CD38+ CiMs are induced in chronic monocytic blood cancer characterized by prominent cachexia. Notably, the emergence of CiMs and the activation of CiM-related gene signatures in monocytes are confirmed in various advanced solid cancers. Stimuli of toll-like receptor 4 signaling are responsible for the induction of CiMs. Genetic inhibition of IL36G-mediated signaling attenuates skeletal muscle loss and rescues cachexia phenotypes in advanced cancer models. These findings indicate that the IL36G-producing subset of neutrophil-like monocytes could be a potential therapeutic target in cancer cachexia.

Supplementation with Fish Oil and Selenium Protects Lipolytic and Thermogenic Depletion of Adipose in Cachectic Mice Treated with an EGFR Inhibitor

Lung cancer and cachexia are the leading causes of cancer-related deaths worldwide. Cachexia is manifested by weight loss and white adipose tissue (WAT) atrophy. Limited nutritional supplements are conducive to lung cancer patients, whereas the underlying mechanisms are poorly understood. In this study, we used a murine cancer cachexia model to investigate the effects of a nutritional formula (NuF) rich in fish oil and selenium yeast as an adjuvant to enhance the drug efficacy of an EGFR inhibitor (Tarceva). In contrast to the healthy control, tumor-bearing mice exhibited severe cachexia symptoms, including tissue wasting, hypoalbuminemia, and a lower food efficiency ratio. Experimentally, Tarceva reduced pEGFR and HIF-1α expression. NuF decreased the expression of pEGFR and HIF-2α, suggesting that Tarceva and NuF act differently in prohibiting tumor growth and subsequent metastasis. NuF blocked LLC tumor-induced PTHrP and expression of thermogenic factor UCP1 and lipolytic enzymes (ATGL and HSL) in WAT. NuF attenuated tumor progression, inhibited PTHrP-induced adipose tissue browning, and maintained adipose tissue integrity by modulating heat shock protein (HSP) 72. Added together, Tarceva in synergy with NuF favorably improves cancer cachexia as well as drug efficacy.

The role of interleukin-6 family cytokines in cancer cachexia

Cachexia is a wasting syndrome that manifests in more than half of all cancer patients. Cancer-associated cachexia negatively influences the survival of patients and their quality of life. It is characterized by a rapid loss of adipose and skeletal muscle tissues, which is partly mediated by inflammatory cytokines. Here, we explored the crucial roles of interleukin-6 (IL-6) family cytokines, including IL-6, leukemia inhibitory factor, and oncostatin M, in the development of cancer cachexia. These cytokines have been shown to exacerbate cachexia by promoting the wasting of adipose and muscle tissues, activating mechanisms that enhance lipolysis and proteolysis. Overlapping effects of the IL-6 family cytokines depend on janus kinase/signal transducer and activator of transcription 3 signaling. We argue that the blockade of these cytokine pathways individually may fail due to redundancy and future therapeutic approaches should target common downstream elements to yield effective clinical outcomes.

Circular RNAs in human diseases

Circular RNAs (circRNAs) are a unique class of RNA molecules formed through back-splicing rather than linear splicing. As an emerging field in molecular biology, circRNAs have garnered significant attention due to their distinct structure and potential functional implications. A comprehensive understanding of circRNAs' functions and potential clinical applications remains elusive despite accumulating evidence of their involvement in disease pathogenesis. Recent research highlights their significant roles in various human diseases, but comprehensive reviews on their functions and applications remain scarce. This review provides an in-depth examination of circRNAs, focusing first on their involvement in non-neoplastic diseases such as respiratory, endocrine, metabolic, musculoskeletal, cardiovascular, and renal disorders. We then explore their roles in tumors, with particular emphasis on exosomal circular RNAs, which are crucial for cancer initiation, progression, and resistance to treatment. By detailing their biogenesis, functions, and impact on disease mechanisms, this review underscores the potential of circRNAs as diagnostic biomarkers and therapeutic targets. The review not only enhances our understanding of circRNAs' roles in specific diseases and tumor types but also highlights their potential as novel diagnostic and therapeutic tools, thereby paving the way for future clinical investigations and potential therapeutic interventions.

The Different Shades of Thermogenic Adipose Tissue

PURPOSE OF REVIEW

By providing a concise overview of adipose tissue types, elucidating the regulation of adipose thermogenic capacity in both physiological contexts and chronic wasting diseases (a protracted hypermetabolic state that precipitates sustained catabolism and consequent progressive corporeal atrophy), and most importantly, delving into the ongoing discourse regarding the role of adipose tissue thermogenic activation in chronic wasting diseases, this review aims to provide researchers with a comprehensive understanding of the field.

RECENT FINDINGS

Adipose tissue, traditionally classified as white, brown, and beige (brite) based on its thermogenic activity and potential, is intricately regulated by complex mechanisms in response to exercise or cold exposure. This regulation is adipose depot-specific and dependent on the duration of exposure. Excessive thermogenic activation of adipose tissue has been observed in chronic wasting diseases and has been considered a pathological factor that accelerates disease progression. However, this conclusion may be confounded by the detrimental effects of excessive lipolysis. Recent research also suggests that such activation may play a beneficial role in the early stages of chronic wasting disease and provide potential therapeutic effects. A more comprehensive understanding of the changes in adipose tissue thermogenesis under physiological and pathological conditions, as well as the underlying regulatory mechanisms, is essential for the development of novel interventions to improve health and prevent disease.

Brown adipose tissue facilitates the fever response following infection with Salmonella enterica serovar Typhimurium in mice

Brown adipose tissue (BAT) combusts lipids and glucose to generate heat. Via this process of nonshivering thermogenesis, BAT plays a pivotal role in thermoregulation in cold environments, but its contribution to immune-induced fever is less clear. Male APOE∗3-Leiden.CETP mice, a well-established model for human-like lipoprotein metabolism, and wild-type mice were given an intraperitoneal injection of Salmonella enterica serovar Typhimurium (S.tm). Energy expenditure and substrate utilization, plasma lipid levels, fatty acid (FA) uptake by adipose tissues, and lipid content and thermogenic markers in adipose tissues were examined. S.tm infection led to a set of characteristic symptoms, including elevated body temperature and decreased body weight. Whole-body energy expenditure was significantly decreased 72 h postinfection, but fat oxidation was increased and accompanied by a substantial reduction in plasma triglyceride (TG) levels as demonstrated in APOE∗3-Leiden.CETP mice. S.tm infection strongly increased uptake of FAs from TG-rich lipoproteins by BAT, which showed a positive correlation with body temperature in infected mice. Upon histological examination of BAT from wild-type or APOE∗3-Leiden.CETP mice, elevated levels of tyrosine hydroxylase were observed, indicative of stimulated sympathetic activity. In addition, the gene expression profile was consistent with more adrenergic stimulation, while lipid content was reduced. Furthermore, browning of white adipose tissue was observed, evidenced by a modest increase in TG-derived FA uptake, the presence of multilocular cells, and induction of uncoupling protein 1 expression. We proposed that BAT, or thermogenic adipose tissue in general, is involved in the maintenance of elevated body temperature upon invasive bacterial infection.

Impact of body composition on outcomes of immune checkpoint inhibitor combination therapy in patients with previously untreated advanced renal cell carcinoma

BACKGROUND

Data on the association between body composition and outcomes in patients with advanced renal cell carcinoma (RCC) treated with immune checkpoint inhibitor (ICI) combination therapy are limited.

METHODS

We retrospectively evaluated the clinical and radiographic data of 159 patients with advanced RCC, including 84 receiving ICI dual combination therapy (immunotherapy [IO]-IO group) and 75 receiving combinations of ICIs with tyrosine kinase inhibitors (TKIs) (IO-TKI group). Pretreatment computed tomography images were used to calculate body composition, including skeletal muscle mass and fat tissue area. Sarcopenia was defined based on skeletal muscle and psoas muscle indexes. The total fat index, subcutaneous fat index (SFI), and visceral fat index were also calculated.

RESULTS

In the IO-IO treatment group, there was no significant association between body composition and survival or tumor response (P > 0.05). In the IO-TKI treatment group, the high SFI was associated with longer progression-free survival (hazard ratio, 2.70; P = 0.0091) and overall survival (hazard ratio, 26.0; P = 0.0246) than the low SFI, which remained significant after adjusting for covariates. Furthermore, in the high-SFI population, patients treated with IO-TKI therapy had longer progression-free survival (P = 0.0019) and overall survival (P = 0.0287) than those treated with IO-IO therapy, while there was no significant survival difference between the 2 treatment groups in the low-SFI population (P > 0.05).

CONCLUSION

The SFI can be potentially utilized as an effective predictive and prognostic biomarker for first-line ICI combination therapy for advanced RCC.

Role of the sympathetic nervous system in cancer-associated cachexia and tumor progression in tumor-bearing BALB/c mice

BACKGROUND

Adipose and muscle tissue wasting outlines the cachectic process during tumor progression. The sympathetic nervous system (SNS) is known to promote tumor progression and research suggests that it might also contribute to cancer-associated cachexia (CAC) energetic expenditure through fat wasting.

METHODS

We sympathectomized L5178Y-R tumor-bearing male BALB/c mice by intraperitoneally administering 6-hydroxydopamine to evaluate morphometric, inflammatory, and molecular indicators of CAC and tumor progression.

RESULTS

Tumor burden was associated with cachexia indicators, including a 10.5% body mass index (BMI) decrease, 40.19% interscapular, 54% inguinal, and 37.17% visceral adipose tissue loss, a 12% food intake decrease, and significant (p = 0.038 and p = 0.0037) increases in the plasmatic inflammatory cytokines IL-6 and IFN-γ respectively. Sympathectomy of tumor-bearing mice was associated with attenuated BMI and visceral adipose tissue loss, decreased interscapular Ucp-1 gene expression to basal levels, and 2.6-fold reduction in Mmp-9 relative gene expression, as compared with the unsympathectomized mice control group.

CONCLUSION

The SNS contributes to CAC-associated morphometric and adipose tissue alterations and promotes tumor progression in a murine model.

Nutritional Mechanisms of Cancer Cachexia

Cancer cachexia is a complex systemic wasting syndrome. Nutritional mechanisms that span energy intake, nutrient metabolism, body composition, and energy balance may be impacted by, and may contribute to, the development of cachexia. To date, clinical management of cachexia remains elusive. Leaning on discoveries and novel methodologies from other fields of research may bolster new breakthroughs that improve nutritional management and clinical outcomes. Characteristics that compare and contrast cachexia and obesity may reveal opportunities for cachexia research to adopt methodology from the well-established field of obesity research. This review outlines the known nutritional mechanisms and gaps in the knowledge surrounding cancer cachexia. In parallel, we present how obesity may be a different side of the same coin and how obesity research has tackled similar research questions. We present insights into how cachexia research may utilize nutritional methodology to expand our understanding of cachexia to improve definitions and clinical care in future directions for the field.

The Role of Adipocytes Recruited as Part of Tumor Microenvironment in Promoting Colorectal Cancer Metastases

Adipose tissue dysfunction, which is associated with an increased risk of colorectal cancer (CRC), is a significant factor in the pathophysiology of obesity. Obesity-related inflammation and extracellular matrix (ECM) remodeling promote colorectal cancer metastasis (CRCM) by shaping the tumor microenvironment (TME). When CRC occurs, the metabolic symbiosis of tumor cells recruits adjacent adipocytes into the TME to supply energy. Meanwhile, abundant immune cells, from adipose tissue and blood, are recruited into the TME, which is stimulated by pro-inflammatory factors and triggers a chronic local pro-inflammatory TME. Dysregulated ECM proteins and cell surface adhesion molecules enhance ECM remodeling and further increase contractibility between tumor and stromal cells, which promotes epithelial-mesenchymal transition (EMT). EMT increases tumor migration and invasion into surrounding tissues or vessels and accelerates CRCM. Colorectal symbiotic microbiota also plays an important role in the promotion of CRCM. In this review, we provide adipose tissue and its contributions to CRC, with a special emphasis on the role of adipocytes, macrophages, neutrophils, T cells, ECM, and symbiotic gut microbiota in the progression of CRC and their contributions to the CRC microenvironment. We highlight the interactions between adipocytes and tumor cells, and potential therapeutic approaches to target these interactions.

Extracellular vesicles in tumor-adipose tissue crosstalk: key drivers and therapeutic targets in cancer cachexia

Cancer cachexia is a complex metabolic syndrome characterized by unintentional loss of skeletal muscle and body fat. This syndrome is frequently associated with different types of cancer and negatively affects the prognosis and outcome of these patients. It involves a dynamic interplay between tumor cells and adipose tissue, where tumor-derived extracellular vesicles (EVs) play a crucial role in mediating intercellular communication. Tumor cells release EVs containing bioactive molecules such as hormones (adrenomedullin, PTHrP), pro-inflammatory cytokines (IL-6), and miRNAs (miR-1304-3p, miR-204-5p, miR-155, miR-425-3p, miR-146b-5p, miR-92a-3p), which can trigger lipolysis and induce the browning of white adipocytes contributing to a cancer cachexia phenotype. On the other hand, adipocyte-derived EVs can reprogram the metabolism of tumor cells by transporting fatty acids and enzymes involved in fatty acid oxidation, resulting in tumor growth and progression. These vesicles also carry leptin and key miRNAs (miR-155-5p, miR-10a-3p, miR-30a-3p, miR-32a/b, miR-21), thereby supporting tumor cell proliferation, metastasis formation, and therapy resistance. Understanding the intricate network underlying EV-mediated communication between tumor cells and adipocytes can provide critical insights into the mechanisms driving cancer cachexia. This review consolidates current knowledge on the crosstalk between tumor cells and adipose tissue mediated by EVs and offers valuable insights for future research. It also addresses controversial topics in the field and possible therapeutic approaches to manage cancer cachexia and ultimately improve patient outcomes and quality of life.

Engineering an energy-dissipating hybrid tissue in vivo for obesity treatment

Obesity is a global health challenge with limited therapeutic solutions. Here, we demonstrate the engineering of an energy-dissipating hybrid tissue (EDHT) in the body for weight control. EDHT is constructed by implanting a synthetic gel matrix comprising immunomodulatory signals and functional cells into the recipient mouse. The immunomodulatory signals induce the host stromal cells to create an immunosuppressive niche that protects the functional cells, which are overexpressing the uncoupling protein 1 (UCP1), from immune rejection. Consequently, these endogenous and exogenous cells co-develop a hybrid tissue that sustainedly produces UCP1 to accelerate the host's energy expenditure. Systematic experiments in high-fat diet (HFD) and transgenic (ob/ob) mice show that EDHT efficiently reduces body weight and relieves obesity-associated pathological conditions. Importantly, an 18-month observation for safety assessment excludes cell leakage from EDHT and reports no adverse physiological responses. Overall, EDHT demonstrates convincing efficacy and safety in controlling body weight.

Exosomal miRNA 16-5p/29a-3p from pancreatic cancer induce adipose atrophy by inhibiting adipogenesis and promoting lipolysis

Over 80% of the patients with pancreatic ductal adenocarcinoma (PDAC) have cachexia/wasting syndrome. Cachexia is associated with reduced survival, decreased quality of life, and higher metastasis rates. Here, we demonstrate that fat loss is the earliest feature of PDAC-exosome-induced cachexia. MicroRNA sequencing of exosomal components from normal and cancer-derived exosomes revealed enrichment of miR-16-5p, miR-21-5p, miR-29a-3p, and miR-125b-5p in serum exosomes of mice harboring PDAC and patients with PDAC. Further, miR-16-5p and miR-29a-3p inhibited adipogenesis through decreasing Erlin2 and Cmpk1 expression which downregulates C/EBPβ and PPARγ. Synergistically, miR-29a-3p promotes lipolysis through increasing ATGL expression by suppressing MCT1 expression. Furthermore, PDAC-exosomes deprived of miR-16-5p and miR-29a-3p fail to induce fat loss. Hence, miR-16-5p and miR-29a-3p exosomal miRs are essential for PDAC-induced fat loss. Thus, we unravel that PDAC induces adipose atrophy via exosomal miRs. This knowledge may provide new diagnostic and therapeutic strategies for PDAC-induced cachexia.

Cancer-associated adipocytes in the ovarian cancer microenvironment

The tumor microenvironment (TME) plays a critical role in high energy metabolism during tumorigenesis, progression and metastasis. Among them, adipocytes, as an important component of the TME, can transform into cancer-associated adipocytes (CAAs) through dedifferentiation via interactions with tumor cells. These CAAs provide nutrients, growth factors, cytokines and metabolites to the tumor and later transdifferentiate into other stromal cells at a later stage to alter tumor growth, metastasis and the drug response and ultimately influence the treatment and prognosis of ovarian cancer. This review outlines the physiological functions of CAAs and discusses the progress in the use of CAAs as therapeutic targets in ovarian cancer.

Tumor metabolic activity is associated with subcutaneous adipose tissue radiodensity and survival in non-small cell lung cancer

BACKGROUND

Cachexia-associated body composition alterations and tumor metabolic activity are both associated with survival of cancer patients. Recently, subcutaneous adipose tissue properties have emerged as particularly prognostic body composition features. We hypothesized that tumors with higher metabolic activity instigate cachexia related peripheral metabolic alterations, and investigated whether tumor metabolic activity is associated with body composition and survival in patients with non-small-cell lung cancer (NSCLC), focusing on subcutaneous adipose tissue.

METHODS

A retrospective analysis was performed on a cohort of 173 patients with NSCLC. 18F-fluorodeoxyglucose positron emission tomography-computed tomography (PET-CT) scans obtained before treatment were used to analyze tumor metabolic activity (standardized uptake value (SUV) and SUV normalized by lean body mass (SUL)) as well as body composition variables (subcutaneous and visceral adipose tissue radiodensity (SAT/VAT radiodensity) and area; skeletal muscle radiodensity (SM radiodensity) and area). Subjects were divided into groups with high or low SAT radiodensity based on Youden Index of Receiver Operator Characteristics (ROC). Associations between tumor metabolic activity, body composition variables, and survival were analyzed by Mann-Whitney tests, Cox regression, and Kaplan-Meier analysis.

RESULTS

The overall prevalence of high SAT radiodensity was 50.9% (88/173). Patients with high SAT radiodensity had shorter survival compared with patients with low SAT radiodensity (mean: 45.3 vs. 50.5 months, p = 0.026). High SAT radiodensity was independently associated with shorter overall survival (multivariate Cox regression HR = 1.061, 95% CI: 1.022-1.101, p = 0.002). SAT radiodensity also correlated with tumor metabolic activity (SULpeak rs = 0.421, p = 0.029; SUVpeak rs = 0.370, p = 0.048). In contrast, the cross-sectional areas of SM, SAT, and VAT were not associated with tumor metabolic activity or survival.

CONCLUSION

Higher SAT radiodensity is associated with higher tumor metabolic activity and shorter survival in patients with NSCLC. This may suggest that tumors with higher metabolic activity induce subcutaneous adipose tissue alterations such as decreased lipid density, increased fibrosis, or browning.