Cancer cachexia associates with a systemic autophagy-inducing activity mimicked by cancer cell-derived IL-6 trans-signaling

The role of TGF-β signaling in muscle atrophy, sarcopenia and cancer cachexia

Skeletal muscle, comprising a significant proportion (40 to 50 percent) of total body weight in humans, plays a critical role in maintaining normal physiological conditions. Muscle atrophy occurs when the rate of protein degradation exceeds protein synthesis. Sarcopenia refers to age-related muscle atrophy, while cachexia represents a more complex form of muscle wasting associated with various diseases such as cancer, heart failure, and AIDS. Recent research has highlighted the involvement of signaling pathways, including IGF1-Akt-mTOR, MuRF1-MAFbx, and FOXO, in regulating the delicate balance between muscle protein synthesis and breakdown. Myostatin, a member of the TGF-β superfamily, negatively regulates muscle growth and promotes muscle atrophy by activating Smad2 and Smad3. It also interacts with other signaling pathways in cachexia and sarcopenia. Inhibition of myostatin has emerged as a promising therapeutic approach for sarcopenia and cachexia. Additionally, other TGF-β family members, such as TGF-β1, activin A, and GDF11, have been implicated in the regulation of skeletal muscle mass. Furthermore, myostatin cooperates with these family members to impair muscle differentiation and contribute to muscle loss. This review provides an overview of the significance of myostatin and other TGF-β signaling pathway members in muscular dystrophy, sarcopenia, and cachexia. It also discusses potential novel therapeutic strategies targeting myostatin and TGF-β signaling for the treatment of muscle atrophy.

IL-6 promotes tumor growth through immune evasion but is dispensable for cachexia

Various cytokines have been implicated in cancer cachexia. One such cytokine is IL-6, deemed as a key cachectic factor in mice inoculated with colon carcinoma 26 (C26) cells, a widely used cancer cachexia model. Here we tested the causal role of IL-6 in cancer cachexia by knocking out the IL-6 gene in C26 cells. We found that the growth of IL-6 KO tumors was dramatically delayed. More strikingly, while IL-6 KO tumors eventually reached the similar size as wild-type tumors, cachexia still took place, despite no elevation in circulating IL-6. In addition, the knockout of leukemia inhibitory factor (LIF), another IL-6 family cytokine proposed as a cachectic factor in the model, also affected tumor growth but not cachexia. We further showed an increase in the infiltration of immune cell population in the IL-6 KO tumors compared with wild-type controls and the defective IL-6 KO tumor growth was rescued in immunodeficient mice while cachexia was not. Thus, IL-6 promotes tumor growth by facilitating immune evasion but is dispensable for cachexia.

The interplay between autophagy and cGAS-STING signaling and its implications for cancer

Autophagy is an intracellular process that targets various cargos for degradation, including members of the cGAS-STING signaling cascade. cGAS-STING senses cytosolic double-stranded DNA and triggers an innate immune response through type I interferons. Emerging evidence suggests that autophagy plays a crucial role in regulating and fine-tuning cGAS-STING signaling. Reciprocally, cGAS-STING pathway members can actively induce canonical as well as various non-canonical forms of autophagy, establishing a regulatory network of feedback mechanisms that alter both the cGAS-STING and the autophagic pathway. The crosstalk between autophagy and the cGAS-STING pathway impacts a wide variety of cellular processes such as protection against pathogenic infections as well as signaling in neurodegenerative disease, autoinflammatory disease and cancer. Here we provide a comprehensive overview of the mechanisms involved in autophagy and cGAS-STING signaling, with a specific focus on the interactions between the two pathways and their importance for cancer.

The autophagy inhibitor NSC185058 suppresses mTORC1-mediated protein anabolism in cultured skeletal muscle

The mammalian target of rapamycin (mTOR), and specifically the mTOR complex 1 (mTORC1) is the central regulator of anabolism in skeletal muscle. Among the many functions of this kinase complex is the inhibition of the catabolic process of autophagy; however, less work has been done in investigating the role of autophagy in regulating mTORC1 signaling. Using an in vitro model to better understand the pathways involved, we activated mTORC1 by several different means (growth factors, leucine supplementation, or muscle contraction), alone or with the autophagy inhibitor NSC185058. We found that inhibiting autophagy with NSC185058 suppresses mTORC1 activity, preventing any increase in cellular protein anabolism. These decrements were the direct result of action on the mTORC1 kinase, which we demonstrate, for the first time, cannot function when autophagy is inhibited by NSC185058. Our results indicate that, far from being a matter of unidirectional action, the relationship between mTORC1 and the autophagic cascade is more nuanced, with autophagy serving as an mTORC1 input, and mTORC1 inhibition of autophagy as a form of homeostatic feedback to regulate anabolic signaling. Future studies of cellular metabolism will have to consider this fundamental intertwining of protein anabolism and catabolism, and how it ultimately serves to regulate muscle proteostasis.

Cancer-associated muscle weakness - From triggers to molecular mechanisms

Skeletal muscle weakness is a debilitating consequence of many malignancies. Muscle weakness has a negative impact on both patient wellbeing and outcome in a range of cancer types and can be the result of loss of muscle mass (i.e. muscle atrophy, cachexia) and occur independently of muscle atrophy or cachexia. There are multiple cancer specific triggers that can initiate the progression of muscle weakness, including the malignancy itself and the tumour environment, as well as chemotherapy, radiotherapy and malnutrition. This can induce weakness via different routes: 1) impaired intrinsic capacity (i.e., contractile dysfunction and intramuscular impairments in excitation-contraction coupling or crossbridge cycling), 2) neuromuscular disconnection and/or 3) muscle atrophy. The mechanisms that underlie these pathways are a complex interplay of inflammation, autophagy, disrupted protein synthesis/degradation, and mitochondrial dysfunction. The current lack of therapies to treat cancer-associated muscle weakness highlight the critical need for novel interventions (both pharmacological and non-pharmacological) and mechanistic insight. Moreover, most research in the field has placed emphasis on directly improving muscle mass to improve muscle strength. However, accumulating evidence suggests that loss of muscle function precedes atrophy. This review primarily focuses on cancer-associated muscle weakness, independent of cachexia, and provides a solid background on the underlying mechanisms, methodology, current interventions, gaps in knowledge, and limitations of research in the field. Moreover, we have performed a mini-systematic review of recent research into the mechanisms behind muscle weakness in specific cancer types, along with the main pathways implicated.

Advancing cancer cachexia diagnosis with -omics technology and exercise as molecular medicine

Muscle atrophy exacerbates disease outcomes and increases mortality, whereas the preservation of skeletal muscle mass and function play pivotal roles in ensuring long-term health and overall quality-of-life. Muscle atrophy represents a significant clinical challenge, involving the continued loss of muscle mass and strength, which frequently accompany the development of numerous types of cancer. Cancer cachexia is a highly prevalent multifactorial syndrome, and although cachexia is one of the main causes of cancer-related deaths, there are still no approved management strategies for the disease. The etiology of this condition is based on the upregulation of systemic inflammation factors and catabolic stimuli, resulting in the inhibition of protein synthesis and enhancement of protein degradation. Numerous necessary cellular processes are disrupted by cachectic pathology, which mediate intracellular signalling pathways resulting in the net loss of muscle and organelles. However, the exact underpinning molecular mechanisms of how these changes are orchestrated are incompletely understood. Much work is still required, but structured exercise has the capacity to counteract numerous detrimental effects linked to cancer cachexia. Primarily through the stimulation of muscle protein synthesis, enhancement of mitochondrial function, and the release of myokines. As a result, muscle mass and strength increase, leading to improved mobility, and quality-of-life. This review summarises existing knowledge of the complex molecular networks that regulate cancer cachexia and exercise, highlighting the molecular interplay between the two for potential therapeutic intervention. Finally, the utility of mass spectrometry-based proteomics is considered as a way of establishing early diagnostic biomarkers of cachectic patients.

Cachexia is associated with depression, anxiety and quality of life in cancer patients

OBJECTIVES

This study aimed to compare depression, anxiety and quality of life (QoL) between cachexia and non-cachexia patients, and explore the relationship between cachexia and depression, anxiety and QoL in patients with cancer.

METHODS

A total of 528 patients from cancer centres of four hospitals were enrolled in this cross-sectional study. All patients were divided into cachexia and non-cachexia according to international consensus definition of cachexia. Patient Health Questionnaire-9 (PHQ-9), Generalized Anxiety Disorder-7 (GAD-7) and Quality of Life Questionnaire-Cancer 30 (QLQ-C30) were used to evaluate depression, anxiety and QoL.

RESULTS

285 patients (53.98%) were classified as cachexia. The prevalence of depression, anxiety, severe depression and severe anxiety in cachexia was 30.2%, 18.6%, 6.7% and 8.4%, respectively, which were significantly higher than in non-cachexia (all p<0.01). Patients with cachexia obviously acquired poorer physical function (PF), role function (RF), cognitive function (CF), emotional function (EF), social function (SF) and overall QoL than non-cachexia patients (all p<0.01). Cachexia was positively associated with depression (unstandardised coefficient (B)=2.123, p<0.001) and anxiety (B=1.123, p=0.024), and had a negative relationship with PF, CF, EF, SF and overall QoL (all B<0, all p<0.05).

CONCLUSIONS

Cachexia was associated with greater depression and anxiety and poorer QoL in patients with cancer, which emphasised the importance of timely identification and management of cachexia to improve the psychological problems and QoL among patients with cancer.

Cancer Cachexia and breast cancer stem cell signalling - A crosstalk of signalling molecules

Cancer Cachexia is a condition characterized by the involuntary loss of lean body mass, a negative protein and energy balance, and systemic inflammation. This syndrome profoundly impacts the patient's quality of life and is linked to poor chemotherapy response and reduced survival. Despite multiple mechanisms being implicated in its development, and various cytokines believed to contribute to the persistent catabolic state, cachexia is still not fully recognized and is often left untreated. Cachexia is caused by altered metabolic adaptation and lack of anticactic therapy due to systemic cytokines promoting and fuelling cancer growth. The exact molecular mechanisms and clinical endpoints remain poorly defined. It has an occurrence rate of 30%-80%, accounting for 20% of total cancer mortality. Tumor cells remodel the microenvironment suitable for their proliferation, wherein they communicate with fibroblast cells to modulate their expression and induce tumor progressive cytokines. Several studies have reported its strong correlation with systemic cytokines that initiate and aggravate the condition. Plenty of studies show the prominent role of cancer-induced cachexia in pancreatic cancer, colon cancer, and lung cancer. However, limited data are available for breast cancer-induced cachexia, highlighting the need for studying it. Breast cancer stem cells (BCSCs) are a prominently explored area in breast cancer research. They are characterized by CD44+/CD24-/ALDH+ expression and are a focus of cancer research. They are a source of renewal and differentiation within the tumor environment and are responsible for progression, and chemotherapeutic resistance. The tumor microenvironment and its cytokines are responsible for maintaining and inducing their differentiation. Cytokines significantly impact BCSC development and self-renewal, stimulating or inhibiting proliferation depending on cytokine and environment. Pro-inflammatory mediators like IL-6, TNF-α, and IL-8 increase proliferation, promoting tumor growth. Experimental models and clinical studies have shown a direct relationship between cytokines and BCSC proliferation. Several of them seem to be interconnected as they initiate signalling down different pathways but converge at BCSC increase and tumor proliferation. This review highlights the common pathways between cachexia and BCSC signalling, to identify potential therapeutic targets that can aid both conditions.

The uncharacterized transcript KIAA0930 confers a cachexic phenotype on cancer cells

Patients with cancer cachexia have a poor prognosis and impaired quality of life. Numerous studies using preclinical models have shown that inflammatory cytokines play an important role in the development of cancer cachexia; however, no clinical trial targeting cytokines has been successful. Therefore, it is essential to identify molecular mechanisms to develop anti-cachexia therapies. Here we identified the uncharacterized transcript KIAA0930 as a candidate cachexic factor based on analyses of microarray datasets and an in vitro muscle atrophy assay. While conditioned media from pancreatic, colorectal, gastric, and tongue cancer cells caused muscle atrophy in vitro, conditioned medium from KIAA0930 knockdown cells did not. The PANC-1 orthotopic xenograft study showed that the tibialis anterior muscle weight and cross-sectional area were increased in mice bearing KIAA0930 knockdown cells compared to control mice. Interestingly, KIAA0930 knockdown did not cause consistent changes in the secretion of inflammatory cytokines/chemokines from a variety of cancer cell lines. An initial characterization experiment showed that KIAA0930 is localized in the cytosol and not secreted from cells. These data suggest that the action of KIAA0930 is independent of the expression of cytokines/chemokines and that KIAA0930 could be a novel therapeutic target for cachexia.

Association of Body Composition and Handgrip Strength with Interleukin-6 (IL-6) and Vitamin D Level in Cancer Patients

Introduction

Cachexia is prevalent in cancer and is associated with poorer prognosis. We aimed to investigate the association of interleukin-6 (IL-6) and vitamin D levels with cachexia in cancer patients. We also assessed the relationship between body composition profile and cachexia, IL-6, and vitamin D levels.

Methods

A cross-sectional study was conducted at Dharmais National Cancer Hospital. The study included patients with newly diagnosed biopsy-proven nasopharyngeal cancer, lung cancer, breast cancer, cervical cancer, or non-Hodgkin lymphoma. Blood samples, anthropometrics, and body composition were measured.

Results

A total of 150 cancer patients were included in the study, with a median age of 52 years, and 64% (n = 96) are female. The prevalence of cachexia was 57%. Cancer patients with cachexia had higher IL-6 levels (P = 0.025). No association between cachexia and vitamin D levels was found (P = 0.787). Patients with cachexia had lower body composition components than those without cachexia (P < 0.05). Vitamin D levels were positively correlated with muscle mass, visceral fat, and handgrip strength (P < 0.05), while no association between IL-6 and body composition was found.

Conclusion

Cancer-associated cachexia is associated with a higher level of IL-6, lower BMI, lower fat mass index, and lower visceral fat. Vitamin D levels, but not IL-6, are correlated with muscle mass, muscle strength, and visceral fat in cancer patients.

IL-6 is dispensable for causing cachexia in the colon carcinoma 26 model

Various cytokines have been implicated in cancer cachexia. One such cytokine is IL-6, which has been deemed a key cachectic factor in mice inoculated with the colon carcinoma 26 (C26) cells, one of the most widely used models of cancer cachexia. Here to test the causal role of IL-6 in cancer cachexia, we used CRISPR/Cas9 editing to knock out IL-6 in C26 cells. We found that growth of IL-6 KO C26 tumors was dramatically delayed. Most strikingly, while IL-6 KO tumors eventually reached the similar size as wild-type tumors, cachexia still took place, despite no elevation in circulating IL-6. We further showed an increase of immune cell populations in IL-6 KO tumors and the defective IL-6 KO tumor growth was rescued in immunodeficient mice. Thus, our results invalidated IL-6 as a necessary factor for causing cachexia in the C26 model and revealed instead its important role in regulating tumor growth via immune suppression.

Conditioned Media from Head and Neck Cancer Cell Lines and Serum Samples from Head and Neck Cancer Patients Drive Catabolic Pathways in Cultured Muscle Cells

BACKGROUND

The role of secreted factors from the tumor cells in driving cancer cachexia and especially muscle loss is unknown. We wanted to study both the action of secreted factors from head and neck cancer (HNC) cell lines and circulating factors in HNC patients on skeletal muscle protein catabolism.

METHODS

Conditioned media (CM) made from head and neck cancer cell lines and mix of sera from head and neck cancer (HNC) patients were incubated for 48 h with human myotubes. The atrophy and the catabolic pathway were monitored in myotubes. The patients were classified regarding their skeletal muscle loss observed at the outset of management.

RESULTS

Tumor CM (TCM) was able to produce atrophy on myotubes as compared with control CM (CCM). However, a mix of sera from HNC patients was not able to produce atrophy in myotubes. Despite this discrepancy on atrophy, we observed a similar regulation of the catabolic pathways by the tumor-conditioned media and mix of sera from cancer patients. The catabolic response after incubation with the mix of sera seemed to depend on the muscle loss seen in patients.

CONCLUSION

This study found evidence that the atrophy observed in HNC patients cannot be solely explained by a deficit in food intake.

Progressive development of melanoma-induced cachexia differentially impacts organ systems in mice

Cachexia is a systemic wasting syndrome that increases cancer-associated mortality. How cachexia progressively and differentially impacts distinct tissues is largely unknown. Here, we find that the heart and skeletal muscle undergo wasting at early stages and are the tissues transcriptionally most impacted by cachexia. We also identify general and organ-specific transcriptional changes that indicate functional derangement by cachexia even in tissues that do not undergo wasting, such as the brain. Secreted factors constitute a top category of cancer-regulated genes in host tissues, and these changes include upregulation of the angiotensin-converting enzyme (ACE). ACE inhibition with the drug lisinopril improves muscle force and partially impedes cachexia-induced transcriptional changes, although wasting is not prevented, suggesting that cancer-induced host-secreted factors can regulate tissue function during cachexia. Altogether, by defining prevalent and temporal and tissue-specific responses to cachexia, this resource highlights biomarkers and possible targets for general and tissue-tailored anti-cachexia therapies.

GDF15 neutralization restores muscle function and physical performance in a mouse model of cancer cachexia

Cancer cachexia is a disorder characterized by involuntary weight loss and impaired physical performance. Decline in physical performance of patients with cachexia is associated with poor quality of life, and currently there are no effective pharmacological interventions that restore physical performance. Here we examine the effect of GDF15 neutralization in a mouse model of cancer-induced cachexia (TOV21G) that manifests weight loss and muscle function impairments. With comprehensive assessments, our results demonstrate that cachectic mice treated with the anti-GDF15 antibody mAB2 exhibit body weight gain with near-complete restoration of muscle mass and markedly improved muscle function and physical performance. Mechanistically, the improvements induced by GDF15 neutralization are primarily attributed to increased caloric intake, while altered gene expression in cachectic muscles is restored in caloric-intake-dependent and -independent manners. The findings indicate potential of GDF15 neutralization as an effective therapy to enhance physical performance of patients with cachexia.

Review of the endocrine organ-like tumor hypothesis of cancer cachexia in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is one of the most fatal types of solid tumors, associated with a high prevalence of cachexia (~80%). PDAC-derived cachexia (PDAC-CC) is a systemic disease involving the complex interplay between the tumor and multiple organs. The endocrine organ-like tumor (EOLT) hypothesis may explain the systemic crosstalk underlying the deleterious homeostatic shifts that occur in PDAC-CC. Several studies have reported a markedly heterogeneous collection of cachectic mediators, signaling mechanisms, and metabolic pathways, including exocrine pancreatic insufficiency, hormonal disturbance, pro-inflammatory cytokine storm, digestive and tumor-derived factors, and PDAC progression. The complexities of PDAC-CC necessitate a careful review of recent literature summarizing cachectic mediators, corresponding metabolic functions, and the collateral impacts on wasting organs. The EOLT hypothesis suggests that metabolites, genetic instability, and epigenetic changes (microRNAs) are involved in cachexia development. Both tumors and host tissues can secrete multiple cachectic factors (beyond only inflammatory mediators). Some regulatory molecules, metabolites, and microRNAs are tissue-specific, resulting in insufficient energy production to support tumor/cachexia development. Due to these complexities, changes in a single factor can trigger bi-directional feedback circuits that exacerbate PDAC and result in the development of irreversible cachexia. We provide an integrated review based on 267 papers and 20 clinical trials from PubMed and ClinicalTrials.gov database proposed under the EOLT hypothesis that may provide a fundamental understanding of cachexia development and response to current treatments.

Autoimmunity, cancer and COVID-19 abnormally activate wound healing pathways: critical role of inflammation

Recent evidence indicates that targeting IL-6 provides broad therapeutic approaches to several diseases. In patients with cancer, autoimmune diseases, severe respiratory infections [e.g. coronavirus disease 2019 (COVID-19)] and wound healing, IL-6 plays a critical role in modulating the systemic and local microenvironment. Elevated serum levels of IL-6 interfere with the systemic immune response and are associated with disease progression and prognosis. As already noted, monoclonal antibodies blocking either IL-6 or binding of IL-6 to receptors have been used/tested successfully in the treatment of rheumatoid arthritis, many cancer types, and COVID-19. Therefore, in the present review, we compare the impact of IL-6 and anti-IL-6 therapy to demonstrate common (pathological) features of the studied diseases such as formation of granulation tissue with the presence of myofibroblasts and deposition of new extracellular matrix. We also discuss abnormal activation of other wound-healing-related pathways that have been implicated in autoimmune disorders, cancer or COVID-19.

Cancer cachexia as a multiorgan failure: Reconstruction of the crime scene

Cachexia is a devastating syndrome associated with the end-stage of several diseases, including cancer, and characterized by body weight loss and severe muscle and adipose tissue wasting. Although different cancer types are affected to diverse extents by cachexia, about 80% of all cancer patients experience this comorbidity, which highly reduces quality of life and response to therapy, and worsens prognosis, accounting for more than 25% of all cancer deaths. Cachexia represents an urgent medical need because, despite several molecular mechanisms have been identified, no effective therapy is currently available for this devastating syndrome. Most studies focus on skeletal muscle, which is indeed the main affected and clinically relevant organ, but cancer cachexia is characterized by a multiorgan failure. In this review, we focus on the current knowledge on the multiple tissues affected by cachexia and on the biomarkers with the attempt to define a chronological pathway, which might be useful for the early identification of patients who will undergo cachexia. Indeed, it is likely that the inefficiency of current therapies might be attributed, at least in part, to their administration in patients at the late stages of cachexia.

Muscular contraction's therapeutic potential for cancer-induced wasting

Skeletal muscle atrophy and dysfunction contribute to cancer patient morbidity and mortality. Cachexia pathophysiology is highly complex, given that perturbations to the systemic cancer environment and the interaction with diverse tissues can contribute to wasting processes. Systemic interleukin 6 (IL-6) and glycoprotein 130 (gp130) receptor signaling have established roles in some types of cancer-induced muscle wasting through disruptions to protein turnover and oxidative capacity. While exercise has documented benefits for cancer prevention and patient survival, there are significant gaps in our understanding of muscle adaptation and plasticity during severe cachexia. Preclinical models have provided valuable insight into the adaptive potential of muscle to contraction within the cancer environment. We summarize the current understanding of how resistance-type exercise impacts mechanisms involved in cancer-induced muscle atrophy and dysfunction. Specifically, the role of IL-6 and gp130 receptor in the pathophysiology of muscle wasting and the adaptive response to exercise is explained. The discussion includes current knowledge gaps and future research directions needed to improve preclinical research and accelerate clinical translation in human cancer patients.

Cancer Cachexia and Antitumor Immunity: Common Mediators and Potential Targets for New Therapies

Cancer cachexia syndrome (CCS) is a multifactorial metabolic syndrome affecting a significant proportion of patients. CCS is characterized by progressive weight loss, alterations of body composition and a systemic inflammatory status, which exerts a major impact on the host’s innate and adaptive immunity. Over the last few years, the development of immune checkpoint inhibitors (ICIs) transformed the treatment landscape for a wide spectrum of malignancies, creating an unprecedented opportunity for long term remissions in a significant subset of patients. Early clinical data indicate that CCS adversely impairs treatment outcomes of patients receiving ICIs. We herein reviewed existing evidence on the potential links between the mechanisms that promote the catabolic state in CCS and those that impair the antitumor immune response. We show that the biological mediators and processes leading to the development of CCS may also participate in the modulation and the sustainment of an immune suppressive tumor microenvironment and impaired anti-tumor immunity. Moreover, we demonstrate that the deregulation of the host’s metabolic homeostasis in cancer cachexia is associated with resistance to ICIs. Further research on the interrelation between cancer cachexia and anti-tumor immunity is required for the effective management of resistance to immunotherapy in this specific but large subgroup of ICI treated individuals.

Ovarian cancer ascites induces skeletal muscle wasting in vitro and reflects sarcopenia in patients

BACKGROUND

Cachexia-associated skeletal muscle wasting or 'sarcopenia' is highly prevalent in ovarian cancer and contributes to poor outcome. Drivers of cachexia-associated sarcopenia in ovarian cancer remain elusive, underscoring the need for novel and better models to identify tumour factors inducing sarcopenia. We aimed to assess whether factors present in ascites of sarcopenic vs. non-sarcopenic ovarian cancer patients differentially affect protein metabolism in skeletal muscle cells and to determine if these effects are correlated to cachexia-related patient characteristics.

METHODS

Fifteen patients with an ovarian mass and ascites underwent extensive physical screening focusing on cachexia-related parameters. Based on computed tomography-based body composition imaging, six cancer patients were classified as sarcopenic and six were not; three patients with a benign condition served as an additional non-sarcopenic control group. Ascites was collected, and concentrations of cachexia-associated factors were assessed by enzyme-linked immunosorbent assay. Subsequently, ascites was used for in vitro exposure of C2C12 myotubes followed by measurements of protein synthesis and breakdown by radioactive isotope tracing, qPCR-based analysis of atrophy-related gene expression, and NF-κB activity reporter assays.

RESULTS

C2C12 protein synthesis was lower after exposure to ascites from sarcopenic patients (sarcopenia 3.1 ± 0.1 nmol/h/mg protein vs. non-sarcopenia 5.5 ± 0.2 nmol/h/mg protein, P < 0.01), and protein breakdown rates tended to be higher (sarcopenia 31.2 ± 5.2% vs. non-sarcopenia 20.9 ± 1.9%, P = 0.08). Ascites did not affect MuRF1, Atrogin-1, or REDD1 expression of C2C12 myotubes, but NF-κB activity was specifically increased in cells exposed to ascites from sarcopenic patients (sarcopenia 2.2 ± 0.4-fold compared with control vs. non-sarcopenia 1.2 ± 0.2-fold compared with control, P = 0.01). Protein synthesis and breakdown correlated with NF-κB activity (r_s  = -0.60, P = 0.03 and r_s  = 0.67, P = 0.01, respectively). The skeletal muscle index of the ascites donors was also correlated to both in vitro protein synthesis (r_s  = 0.70, P = 0.005) and protein breakdown rates (r_s  = -0.57, P = 0.04).

CONCLUSIONS

Ascites of sarcopenic ovarian cancer patients induces pronounced skeletal muscle protein metabolism changes in C2C12 cells that correlate with clinical muscle measures of the patient and that are characteristic of cachexia. The use of ascites offers a new experimental tool to study the impact of both tumour-derived and systemic factors in various cachexia model systems, enabling identification of novel drivers of tissue wasting in ovarian cancer.

The impact of nutritional status on pancreatic cancer therapy

INTRODUCTION

Pancreatic Ductal Adenocarcinoma (PDAC) is an aggressive disease with poor outcomes. One of the reasons for the dismal prognosis resides in its impressive ability to alter the nutritional status of patients who develop malnutrition, cachexia, anorexia, and sarcopenia in most cases. The ideal way to measure such changes in PDAC patients, in order to readily identify them and avoid complications or discontinuations of treatment is a relatively unexplored area. In addition, most PDAC patients experience pancreatic exocrine insufficiency (PEI) that contributes to the complex puzzle of malnutrition and that can be treated with Pancreatic Enzyme Replacement Therapy (PERT).

AREAS COVERED

We review current knowledge on the impact of nutritional status on both surgical and medical treatments for PDAC, reporting available data on the causes of malnutrition, characteristics, and advantages of different tools to investigate nutritional status and possible strategies to improve patient outcomes.

EXPERT OPINION

All PDAC patients should receive a careful nutritional assessment at diagnosis, and this should be repeated alongside their treatment path. Screening tools and biochemical variables or scores are associated with prognosis, but bioimpedance vector analysis (BIVA) and radiological assessment of body composition seem more accurate in predicting clinical outcomes and postoperative complications.

Nutrition challenges of cancer cachexia

Cancer cachexia, or progressive weight loss, often despite adequate nutrition contributes greatly to cancer morbidity and mortality. Cachexia is metabolically distinct from starvation or protein malnutrition, although many patients with cancer and cachexia exhibit lowered appetite and food consumption. Tumors affect neural mechanisms that regulate appetite and energy expenditure, while promoting wasting of peripheral tissues via catabolism of cardiac and skeletal muscle, adipose, and bone. These multimodal actions of tumors on the host suggest a need for multimodal interventions. However, multiple recent consensus guidelines for management of cancer cachexia differ in treatment recommendations, highlighting the lack of effective, available therapies. Challenges to defining appropriate nutrition or other interventions for cancer cachexia include lack of consensus on definitions, low strength of evidence from clinical trials, and a scarcity of robust, rigorous, and mechanistic studies. However, efforts to diagnose, stage, and monitor cachexia are increasing along with clinical trial activity. Furthermore, preclinical models for cancer cachexia are growing more sophisticated, encompassing a greater number of tumor types in organ-appropriate contexts and for metastatic disease to model the clinical condition more accurately. It is expected that continued growth, investment, and coordination of research in this topic will ultimately yield robust biomarkers, clinically useful classification and staging algorithms, targetable pathways, pivotal clinical trials, and ultimately, cures. Here, we provide an overview of the clinical and scientific knowledge and its limitations around cancer cachexia.

MMP12 knockout prevents weight and muscle loss in tumor-bearing mice

BACKGROUND

Colorectal cancer is a malignant gastrointestinal cancer, in which some advanced patients would develop cancer cachexia (CAC). CAC is defined as a multi-factorial syndrome characterized by weight loss and muscle loss (with or without fat mass), leading to progressive dysfunction, thereby increasing morbidity and mortality. Apc^Min/+ mice develop spontaneous intestinal adenoma, which provides an established model of colorectal cancer for CAC study. Upon studying the Apc^Min/+ mouse model, we observed a marked decrease in weight gain beginning around week 15. Such a reduction in weight gain was rescued when Apc^Min/+ mice were crossed with MMP12^-/- mice, indicating that MMP12 has a role in age-related Apc^Min/+-associated weight loss. As a control, the weight of MMP12^-/- mice on a weekly basis, their weight were not significantly different from those of WT mice.

METHODS

Apc^Min/+; MMP12^-/- mice were obtained by crossing Apc^Min/+ mice with MMP12 knockout (MMP12 ^-/-) mice. Histological scores were assessed using hematoxylin-eosin (H&E) staining. MMP12 expression was confirmed by immunohistochemistry and immunofluorescence staining. ELISA, protein microarrays and quantitative Polymerase Chain Reaction (qPCR) were used to investigate whether tumor could up-regulate IL-6. Cell-based assays and western blot were used to verify the regulatory relationship between IL-6 and MMP12. Fluorescence intensity was measured to determine whether MMP12 is associated with insulin and insulin-like growth factor 1 (IGF-1) in vitro. MMP12 inhibitors were used to explore whether MMP12 could affect the body weight of Apc^Min/+ mice.

RESULTS

MMP12 knockout led to weight gain and expansion of muscle fiber cross-sectional area (all mice had C57BL/6 background) in Apc^Min/+ mice, while inhibiting MMP12 could suppress weight loss in Apc^Min/+ mice. MMP12 was up-regulated in muscle tissues and peritoneal macrophages of Apc^Min/+ mice. IL-6 in tumor cells and colorectal cancer patients is up-regulation. IL-6 stimulated MMP12 secretion of macrophage.

CONCLUSIONS

MMP12 is essential for controlling body weight of Apc ^Min/+ mice. Our study shows that it exists the crosstalk between cancer cells and macrophages in muscle tissues that tumor cells secrete IL-6 inducing macrophages to up-regulate MMP12. This study may provide a new perspective of MMP12 in the treatment for weight loss induced by CAC.

A Blueprint for Cancer-Related Inflammation and Host Innate Immunity

Both in situ and allograft models of cancer in juvenile and adult Drosophila melanogaster fruit flies offer a powerful means for unravelling cancer gene networks and cancer-host interactions. They can also be used as tools for cost-effective drug discovery and repurposing. Moreover, in situ modeling of emerging tumors makes it possible to address cancer initiating events-a black box in cancer research, tackle the innate antitumor immune responses to incipient preneoplastic cells and recurrent growing tumors, and decipher the initiation and evolution of inflammation. These studies in Drosophila melanogaster can serve as a blueprint for studies in more complex organisms and help in the design of mechanism-based therapies for the individualized treatment of cancer diseases in humans. This review focuses on new discoveries in Drosophila related to the diverse innate immune responses to cancer-related inflammation and the systemic effects that are so detrimental to the host.

Disrupted NOS2 metabolism drives myoblast response to wasting-associated cytokines

Skeletal muscle wasting drives negative clinical outcomes and is associated with a spectrum of pathologies including cancer. Cancer cachexia is a multi-factorial syndrome that encompasses skeletal muscle wasting and remains understudied, despite being a frequent and serious co-morbidity. Deviation from the homeostatic balance between breakdown and regeneration leads to muscle wasting disorders, such as cancer cachexia. Muscle stem cells (MuSCs) are the cellular compartment responsible for muscle regeneration, which makes MuSCs an intriguing target in the context of wasting muscle. Molecular studies investigating MuSCs and skeletal muscle wasting largely focus on transcriptional changes, but our group and others propose that metabolic changes are another layer of cellular regulation underlying MuSC dysfunction in cancer cachexia. In the present study, we combined gene expression and non-targeted metabolomic profiling of myoblasts exposed to wasting conditions (cancer cell conditioned media, CC-CM) to derive a more complete picture of the myoblast response to wasting factors. After mapping these features to annotated pathways, we found that more than half of the mapped pathways were amino acid-related, linking global amino acid metabolic disruption to conditioned media-induced myoblast defects. Notably, arginine metabolism was a highly enriched pathway in combined metabolomic and transcriptomic data. Arginine catabolism generates nitric oxide (NO), an important signaling molecule known to have negative effects on mature muscle. We hypothesize that tumor-derived disruptions in Nitric Oxide Synthase (NOS)2-regulated arginine catabolism impair differentiation of MuSCs. The work presented here further investigates the effect of NOS2 overactivity on myoblast proliferation and differentiation. We show that NOS2 inhibition is sufficient to rescue wasting phenotypes associated with inflammatory cytokines. Ultimately, this work provides new insights into MuSC biology and opens up potential therapeutic avenues for addressing disrupted MuSC dynamics in cancer cachexia.

Relationship of Cachexia with Self-Care Agency and Quality of Life in Cancer Patients: The Case of Turkey

Objective:

This study aims to determine the effects of cachexia, causing major problems in the world and Turkey, on self-care agency and quality of life in cancer patients.

Methods:

The population of this cross-sectional and relationship-seeking study consisted of cancer patients in Turkey from April 1 to April 20, 2021. Using the snowball sampling method, 174 patients were sampled. “Patient Information Form,” “The European Organization for Research and Treatment of Cancer C30 Cancer Quality of Life Scale,” and “Exercise of Self-Care Agency Scale” were used as data collection tools.

Results:

In the study, 52 patients (29.9%) were found to have cachexia. Function, general well-being, symptom (except insomnia), and self-care agency, which are subdimensions of the quality-of-life scale, were found to be significantly lower in patients with cachexia than patients without cachexia (P < 0.001). It was determined that there was a significant negative correlation between the cachexia status of the patients and the five basic functions in the functional scale (physical, role, emotional, cognitive, and social function), general well-being, and self-care agency, and there was a significant positive correlation between the cachexia status of the patients and the symptom scale (P < 0.001). According to the results of multiple linear regression analysis, it was found that the factor that significantly affected the cachexia status of the patients was their self-care agency (P < 0.001).

Conclusions:

It was determined that cachexia caused significantly lower self-care agency and quality of life in cancer patients. Furthermore, quality of life was related to self-care agency.

Are cachexia-associated tumors transmitTERS of ER stress?

Cancer cachexia is associated with deficient response to chemotherapy. On the other hand, the tumors of cachectic patients remarkably express more chemokines and have higher immune infiltration. For immunogenicity, a strong induction of the unfolded protein response (UPR) is necessary. UPR followed by cell surface exposure of calreticulin on the dying tumor cell is essential for its engulfment by macrophages and dendritic cells. However, some tumor cells upon endoplasmic reticulum (ER) stress can release factors that induce ER stress to other cells, in the so-called transmissible ER stress (TERS). The cells that received TERS produce more interleukin 6 (IL-6) and chemokines and acquire resistance to subsequent ER stress, nutrient deprivation, and genotoxic stress. Since ER stress enhances the release of extracellular vesicles (EVs), we suggest they can mediate TERS. It was found that ER stressed cachexia-inducing tumor cells transmit factors that trigger ER stress in other cells. Therefore, considering the role of EVs in cancer cachexia, the release of exosomes can possibly play a role in the process of blunting the immunogenicity of the cachexia-associated tumors. We propose that TERS can cause an inflammatory and immunosuppressive phenotype in cachexia-inducing tumors.

Drosophila Larval Models of Invasive Tumorigenesis for In Vivo Studies on Tumour/Peripheral Host Tissue Interactions during Cancer Cachexia

Cancer cachexia is a common deleterious paraneoplastic syndrome that represents an area of unmet clinical need, partly due to its poorly understood aetiology and complex multifactorial nature. We have interrogated multiple genetically defined larval Drosophila models of tumourigenesis against key features of human cancer cachexia. Our results indicate that cachectic tissue wasting is dependent on the genetic characteristics of the tumour and demonstrate that host malnutrition or tumour burden are not sufficient to drive wasting. We show that JAK/STAT and TNF-α/Egr signalling are elevated in cachectic muscle and promote tissue wasting. Furthermore, we introduce a dual driver system that allows independent genetic manipulation of tumour and host skeletal muscle. Overall, we present a novel Drosophila larval paradigm to study tumour/host tissue crosstalk in vivo, which may contribute to future research in cancer cachexia and impact the design of therapeutic approaches for this pathology.

Interleukins in cancer: from biology to therapy

Interleukins and associated cytokines serve as the means of communication for innate and adaptive immune cells as well as non-immune cells and tissues. Thus, interleukins have a critical role in cancer development, progression and control. Interleukins can nurture an environment enabling and favouring cancer growth while simultaneously being essential for a productive tumour-directed immune response. These properties of interleukins can be exploited to improve immunotherapies to promote effectiveness as well as to limit side effects. This Review aims to unravel some of these complex interactions.

The Effect of Mechanical Stretch on Myotube Growth Suppression by Colon-26 Tumor-Derived Factors

Preclinical models and in vitro experiments have provided valuable insight into the regulation of cancer-induced muscle wasting. Colon-26 (C26) tumor cells induce cachexia in mice, and conditioned media (CM) from these cells promotes myotube atrophy and catabolic signaling. While mechanical stimuli can prevent some effects of tumor-derived factors on myotubes, the impact of mechanical signaling on tumor-derived factor regulation of myosin heavy chain (MyHC) expression is not well understood. Therefore, we examined the effects of stretch-induced mechanical signaling on C2C12 myotube growth and MyHC expression after C26 CM exposure. C26 CM was administered to myotubes on day 5 of differentiation for 48 h. During the last 4 or 24 h of C26 CM exposure, 5% static uniaxial stretch was administered. C26 CM suppressed myotube growth and MyHC protein and mRNA expression. Stretch for 24 h increased myotube size and prevented the C26 CM suppression of MyHC-Fast protein expression. Stretch did not change suppressed MyHC mRNA expression. Stretch for 24 h reduced Atrogin-1/MAFbx, MuRF-1, and LC3B II/I ratio and increased integrin β1D protein expression and the myogenin-to-MyoD protein ratio. Stretch in the last 4 h of CM increased ERK1/2 phosphorylation but did not alter the CM induction of STAT3 or p38 phosphorylation. These results provide evidence that in myotubes pre-incubated with CM, the induction of mechanical signaling can still provide a growth stimulus and preserve MyHC-Fast protein expression independent of changes in mRNA expression.

Type 2 immunity is maintained during cancer-associated adipose tissue wasting

Objectives: Cachexia is a systemic metabolic disorder characterized by loss of fat and muscle mass, which disproportionately impacts patients with gastrointestinal malignancies such as pancreatic cancer. While the immunologic shifts contributing to the development of other adipose tissue (AT) pathologies such as obesity have been well described, the immune microenvironment has not been studied in the context of cachexia.

Methods: We performed bulk RNA-sequencing, cytokine arrays, and flow cytometry to characterize the immune landscape of visceral AT (VAT) in the setting of pancreatic and colorectal cancers.

Results: The cachexia inducing factor IL-6 is strongly elevated in the wasting VAT of cancer bearing mice, but the regulatory type 2 immune landscape which characterizes healthy VAT is maintained. Pathologic skewing toward Th1 and Th17 inflammation is absent. Similarly, the VAT of patients with colorectal cancer is characterized by a Th2 signature with abundant IL-33 and eotaxin-2, albeit also with high levels of IL-6.

Conclusions: Wasting AT during the development of cachexia may not undergo drastic changes in immune composition like those seen in obese AT. Our approach provides a framework for future immunologic analyses of cancer associated cachexia.

Pancreatic cancer cachexia: three dimensions of a complex syndrome

Cancer cachexia is a multifactorial syndrome that is characterised by a loss of skeletal muscle mass, is commonly associated with adipose tissue wasting and malaise, and responds poorly to therapeutic interventions. Although cachexia can affect patients who are severely ill with various malignant or non-malignant conditions, it is particularly common among patients with pancreatic cancer. Pancreatic cancer often leads to the development of cachexia through a combination of distinct factors, which, together, explain its high prevalence and clinical importance in this disease: systemic factors, including metabolic changes and pathogenic signals related to the tumour biology of pancreatic adenocarcinoma; factors resulting from the disruption of the digestive and endocrine functions of the pancreas; and factors related to the close anatomical and functional connection of the pancreas with the gut. In this review, we conceptualise the various insights into the mechanisms underlying pancreatic cancer cachexia according to these three dimensions to expose its particular complexity and the challenges that face clinicians in trying to devise therapeutic interventions.

Role of myokines and osteokines in cancer cachexia

Cancer-induced muscle wasting, i.e. cachexia, is associated with different types of cancer such as pancreatic, colorectal, lung, liver, gastric and esophageal. Cachexia affects prognosis and survival in cancer, and it is estimated that it will be the ultimate cause of death for up to 30% of cancer patients. Musculoskeletal alterations are known hallmarks of cancer cachexia, with skeletal muscle atrophy and weakness as the most studied. Recent evidence has shed light on the presence of bone loss in cachectic patients, even in the absence of bone-metastatic disease. In particular, we and others have shown that muscle and bone communicate by exchanging paracrine and endocrine factors, known as myokines and osteokines. This review will focus on describing the role of the most studied myokines, such as myostatin, irisin, the muscle metabolite β-aminoisobutyric acid, BAIBA, and IL-6, and osteokines, including TGF-β, osteocalcin, sclerostin, RANKL, PTHrP, FGF23, and the lipid mediator, PGE₂ during cancer-induced cachexia. The interplay of muscle and bone factors, together with tumor-derived soluble factors, characterizes a complex clinical scenario in which musculoskeletal alterations are amongst the most debilitating features. Understanding and targeting the "secretome" of cachectic patients will likely represent a promising strategy to preserve bone and muscle during cancer cachexia thereby enhancing recovery.

Phenotypic features of cancer cachexia-related loss of skeletal muscle mass and function: lessons from human and animal studies

Cancer cachexia is a complex multi-organ catabolic syndrome that reduces mobility, increases fatigue, decreases the efficiency of therapeutic strategies, diminishes the quality of life, and increases the mortality of cancer patients. This review provides an exhaustive and comprehensive analysis of cancer cachexia-related phenotypic changes in skeletal muscle at both the cellular and subcellular levels in human cancer patients, as well as in animal models of cancer cachexia. Cancer cachexia is characterized by a major decrease in skeletal muscle mass in human and animals that depends on the severity of the disease/model and the localization of the tumour. It affects both type 1 and type 2 muscle fibres, even if some animal studies suggest that type 2 muscle fibres would be more prone to atrophy. Animal studies indicate an impairment in mitochondrial oxidative metabolism resulting from a decrease in mitochondrial content, an alteration in mitochondria morphology, and a reduction in mitochondrial metabolic fluxes. Immuno-histological analyses in human and animal models also suggest that a faulty mechanism of skeletal muscle repair would contribute to muscle mass loss. An increase in collagen deposit, an accumulation of fat depot outside and inside the muscle fibre, and a disrupted contractile machinery structure are also phenotypic features that have been consistently reported in cachectic skeletal muscle. Muscle function is also profoundly altered during cancer cachexia with a strong reduction in skeletal muscle force. Even though the loss of skeletal muscle mass largely contributes to the loss of muscle function, other factors such as muscle-nerve interaction and calcium handling are probably involved in the decrease in muscle force. Longitudinal analyses of skeletal muscle mass by imaging technics and skeletal muscle force in cancer patients, but also in animal models of cancer cachexia, are necessary to determine the respective kinetics and functional involvements of these factors. Our analysis also emphasizes that measuring skeletal muscle force through standardized tests could provide a simple and robust mean to early diagnose cachexia in cancer patients. That would be of great benefit to cancer patient's quality of life and health care systems.

Exosomal microRNAs in cancer-related sarcopenia: Tumor-derived exosomal microRNAs in muscle atrophy

Cancer-associated sarcopenia is a complex metabolic syndrome marked by muscle mass wasting. Muscle wasting is a serious complication that is a primary contributor to cancer-related mortality. The underlying molecular mechanisms of cancer-associated sarcopenia have not been completely described to date. In general, evidence shows that the main pathophysiological alterations in sarcopenia are associated with the degradation of cellular components, an exceptional inflammatory secretome and mitochondrial dysfunction. Importantly, we highlight the prospect that several miRNAs carried by tumor-derived exosomes that have shown the ability to promote inflammatory secretion, activate catabolism, and even participate in the regulation of cellular degradation pathways can be delivered to and exert effects on muscle cells. In this review, we aim to describe the current knowledge about the functions of exosomal miRNAs in the induction of cancer-associated muscle wasting and propose potential treatment strategies.

Predictive impact of C-reactive protein to albumin ratio for recurrent or metastatic head and neck squamous cell carcinoma receiving nivolumab

Although the neutrophil to lymphocyte ratio (NLR) was reported to be a predictive biomarker for clinical outcomes in various types of cancer, including recurrent or metastatic head and neck cancer (R/M HNSCC) treated with nivolumab, the usefulness of the pretreatment C-reactive protein/albumin ratio (CAR) as a prognostic marker remains to be clarified. This study aimed to analyze the clinical usability of the CAR in comparison with that of the NLR. 46 R/M HNSCC patients treated with nivolumab were retrospectively analyzed. The optimal cutoff value for the CAR was calculated using receiver operating characteristic curve analysis. The optimal cutoff value for the CAR was set to 0.30. On multivariate analyses, a high CAR was significantly associated with poor overall survival (adjusted HR, 2.19; 95% CI, 1.42–3.47; p < 0.01) and progression-free survival (adjusted HR, 1.98; 95% CI, 1.38–2.80; p < 0.01). The overall response rate and disease control rate for the high CAR patients were lower than for the low CAR patients. The CAR had significantly higher area under the curve values than the NLR at 2 and 4 months. The pretreatment CAR might be an independent marker for prognosis and efficacy in R/M HNSCC patients treated with nivolumab.

Deciphering the Role of the Coagulation Cascade and Autophagy in Cancer-Related Thrombosis and Metastasis

Thrombotic complications are the second leading cause of death among oncology patients worldwide. Enhanced thrombogenesis has multiple origins and may result from a deregulation of megakaryocyte platelet production in the bone marrow, the synthesis of coagulation factors in the liver, and coagulation factor signaling upon cancer and the tumor microenvironment (TME). While a hypercoagulable state has been attributed to factors such as thrombocytosis, enhanced platelet aggregation and Tissue Factor (TF) expression on cancer cells, further reports have suggested that coagulation factors can enhance metastasis through increased endothelial-cancer cell adhesion and enhanced endothelial cell activation. Autophagy is highly associated with cancer survival as a double-edged sword, as can both inhibit and promote cancer progression. In this review, we shall dissect the crosstalk between the coagulation cascade and autophagic pathway and its possible role in metastasis and cancer-associated thrombosis formation. The signaling of the coagulation cascade through the autophagic pathway within the hematopoietic stem cells, the endothelial cell and the cancer cell are discussed. Relevant to the coagulation cascade, we also examine the role of autophagy-related pathways in cancer treatment. In this review, we aim to bring to light possible new areas of cancer investigation and elucidate strategies for future therapeutic intervention.

Cancer-Associated Muscle Wasting-Candidate Mechanisms and Molecular Pathways

Excessive muscle loss is commonly observed in cancer patients and its association with poor prognosis has been well-established. Cancer-associated sarcopenia differs from age-related wasting in that it is not responsive to nutritional intervention and exercise. This is related to its unique pathogenesis, a result of diverse and interconnected mechanisms including inflammation, disordered metabolism, proteolysis and autophagy. There is a growing body of evidence that suggests that the tumor is the driver of muscle wasting by its elaboration of mediators that influence each of these pro-sarcopenic pathways. In this review, evidence for these tumor-derived factors and putative mechanisms for inducing muscle wasting will be reviewed. Potential targets for future research and therapeutic interventions will also be reviewed.

Cachexia, a Systemic Disease beyond Muscle Atrophy

Cachexia is a complication of dismal prognosis, which often represents the last step of several chronic diseases. For this reason, the comprehension of the molecular drivers of such a condition is crucial for the development of management approaches. Importantly, cachexia is a syndrome affecting various organs, which often results in systemic complications. To date, the majority of the research on cachexia has been focused on skeletal muscle, muscle atrophy being a pivotal cause of weight loss and the major feature associated with the steep reduction in quality of life. Nevertheless, defining the impact of cachexia on other organs is essential to properly comprehend the complexity of such a condition and potentially develop novel therapeutic approaches.

Molecular mechanisms of cancer cachexia‑induced muscle atrophy (Review)

Muscle atrophy is a severe clinical problem involving the loss of muscle mass and strength that frequently accompanies the development of numerous types of cancer, including pancreatic, lung and gastric cancers. Cancer cachexia is a multifactorial syndrome characterized by a continuous decline in skeletal muscle mass that cannot be reversed by conventional nutritional therapy. The pathophysiological characteristic of cancer cachexia is a negative protein and energy balance caused by a combination of factors, including reduced food intake and metabolic abnormalities. Numerous necessary cellular processes are disrupted by the presence of abnormal metabolites, which mediate several intracellular signaling pathways and result in the net loss of cytoplasm and organelles in atrophic skeletal muscle during various states of cancer cachexia. Currently, the clinical morbidity and mortality rates of patients with cancer cachexia are high. Once a patient enters the cachexia phase, the consequences are difficult to reverse and the treatment methods for cancer cachexia are very limited. The present review aimed to summarize the recent discoveries regarding the pathogenesis of cancer cachexia-induced muscle atrophy and provided novel ideas for the comprehensive treatment to improve the prognosis of affected patients.

Serum IL6 as a Prognostic Biomarker and IL6R as a Therapeutic Target in Biliary Tract Cancers

PURPOSE

Biliary tract cancer (BTC) is a heterogeneous group of rare gastrointestinal malignancies with dismal prognosis often associated with inflammation. We assessed the prognostic value of IL6 and YKL-40 compared with CA19-9 before and during palliative chemotherapy. We also investigated in mice whether IL6R inhibition in combination with gemcitabine could prolong chemosensitivity.

EXPERIMENTAL DESIGN

A total of 452 Danish participants with advanced (locally advanced and metastatic) BTC were included from six clinical trials (February 2004 to March 2017). Serum CA19-9, IL6, and YKL-40 were measured before and during palliative treatment. Associations between candidate biomarkers and progression-free survival (PFS) and overall survival (OS) were analyzed by univariate and multivariate Cox regression. Effects of inhibiting IL6R and YKL-40 were assessed in vitro, and of IL6R inhibition in vivo.

RESULTS

High pretreatment levels of CA19-9, IL6, and YKL-40, and increasing levels during treatment, were associated with short PFS and OS in patients with advanced BTC. IL6 provided independent prognostic information, independent of tumor location and in patients with normal serum CA19-9. ROC analyses showed that IL6 and YKL-40 were predictive of very short OS (OS < 6 months), whereas CA19-9 was best to predict OS > 1.5 years. Treatment with anti-IL6R and gemcitabine significantly diminished tumor growth when compared with gemcitabine monotherapy in an in vivo transplant model of BTC.

CONCLUSIONS

Serum IL6 and YKL-40 are potential new prognostic biomarkers in BTC. IL6 provides independent prognostic information and may be superior to CA19-9 in certain contexts. Moreover, anti-IL6R should be considered as a new treatment option to sustain gemcitabine response in patients with BTC.

Mitochondrial Metabolism in Cancer Cachexia: Novel Drug Target

BACKGROUND

Cancer cachexia is a metabolic syndrome prevalent in the majority of the advanced cancers and is associated with complications such as anorexia, early satiety, weakness, anaemia, and edema, thereby reducing performance and impairing quality of life. Skeletal muscle wasting is a characteristic feature of cancer-cachexia and mitochondria is responsible for regulating total protein turnover in skeletal muscle tissue.

METHODS

We carried out exhaustive search for cancer cachexia and role of mitochondria in the same in various databases. All the relevant articles were gathered and the pertinent information was extracted out and compiled which was further structured into different sub-sections.

RESULTS

Various findings on the mitochondrial alterations in connection to its disturbed normal physiology in various models of cancer-cachexia have been recently reported, suggesting a significant role of the organelle in the pathogenesis of the complications involved in the disorder. It has also been reported that reduced mitochondrial oxidative capacity is due to reduced mitochondrial biogenesis as well as altered balance between fusion and fission protein activities. Moreover, autophagy in mitochondria (termed as mitophagy) is reported to play an important role in cancer cachexia.

CONCLUSION

The present review aims to put forth the changes occurring in mitochondria and hence explore possible targets which can be exploited in cancer-induced cachexia for treatment of such a debilitating condition.

Non-coding RNAs as Putative Biomarkers of Cancer-Associated Cachexia

Cachexia is a complex metabolic syndrome that determines a severe body weight loss characterized by a marked reduction in muscle mass. About 80% of patients with advanced cancer develop cachexia due to both the tumor itself and cancer treatment (radiotherapy and/or chemotherapy), which is associated to a worse prognosis. Despite its clinical relevance, this syndrome is still under-diagnosed and it lacks effective treatments. Radio-chemotherapy treatment is essential in patients with advanced head and neck cancers (HNSCC). Although this treatment has improved patients' life expectancy, it has also dramatically increased their need for assistance and support. The management of adverse symptoms, including cachexia, is of great importance in order to avoid delays in therapy, reduction of dosages and hospitalizations. MicroRNAs (miRNAs) are small non-coding RNA molecules, which have emerged as powerful biomarkers in stratifying human cancers. Due to their high stability in body fluids, miRNAs might be excellent non-invasive biomarkers for the early detection and follow-up of cancer patients. Here, we will summarize the current knowledge and debate the strong need to identify circulating biomarkers for the early diagnosis of cachexia. We will propose circulating non-coding RNAs as biomarkers for detecting early cachexia and implementing specific treatment. We will also discuss the potential use of circulating miRNAs as biomarkers of cachexia in HNSCC patients' blood samples collected before and after radio-chemotherapy treatment. Our intent is to pave the way to the identification of specific circulating miRNAs associated to cachexia occurrence and to the design of specific interventions aimed at improving the quality of life of cancer patients.

Cancer cachexia has many symptoms but only one cause: anoxia

During nearly 100 years of research on cancer cachexia (CC), science has been reciting the same mantra: it is a multifactorial syndrome. The aim of this paper is to show that the symptoms are many, but they have a single cause: anoxia. CC is a complex and devastating condition that affects a high proportion of advanced cancer patients. Unfortunately, it cannot be reversed by traditional nutritional support and it generally reduces survival time. It is characterized by significant weight loss, mainly from fat deposits and skeletal muscles. The occurrence of cachexia in cancer patients is usually a late phenomenon. The conundrum is why do similar patients with similar tumors, develop cachexia and others do not? Even if cachexia is mainly a metabolic dysfunction, there are other issues involved such as the activation of inflammatory responses and crosstalk between different cell types.  The exact mechanism leading to a wasting syndrome is not known, however there are some factors that are surely involved, such as anorexia with lower calorie intake, increased glycolytic flux, gluconeogenesis, increased lipolysis and severe tumor hypoxia. Based on this incomplete knowledge we put together a scheme explaining the molecular mechanisms behind cancer cachexia, and surprisingly, there is one cause that explains all of its characteristics: anoxia.  With this different view of CC we propose a treatment based on the physiopathology that leads from anoxia to the symptoms of CC.  The fundamentals of this hypothesis are based on the idea that CC is the result of anoxia causing intracellular lactic acidosis. This is a dangerous situation for cell survival which can be solved by activating energy consuming gluconeogenesis. The process is conducted by the hypoxia inducible factor-1α. This hypothesis was built by putting together pieces of evidence produced by authors working on related topics.

A novel transplantable model of lung cancer-associated tissue loss and disrupted muscle regeneration

BACKGROUND

Cancer-associated muscle wasting (CAW), a symptom of cancer cachexia, is associated with approximately 20% of lung cancer deaths and remains poorly characterized on a mechanistic level. Current animal models for lung cancer-associated cachexia are limited in that they (1) primarily employ flank transplantation methods, (2) have short survival times not reflective of the patient condition, and (3) are typically performed in young mice not representative of mean patient age. This study investigates a new model for lung cancer-associated cachexia that can address these issues and also implicates muscle regeneration as a contributor to CAW.

METHODS

We used tail vein injection as a method to introduce tumor cells that seed primarily in the lungs of mice. Body composition of tumor-bearing mice was longitudinally tracked using NMR-based, echo magnetic resonance imaging (echoMRI). These data were combined with histological and molecular assessments of skeletal muscle to provide a complete analysis of muscle wasting.

RESULTS

In this new lung CAW model, we observed (1) progressive loss in whole body weight, (2) progressive loss of lean and fat mass, (3) a circulating cytokine/inflammatory profile similar to that seen in other models of CAW, (4) histological changes associated with muscle wasting, and (5) molecular changes in muscle that implicate suppression of muscle repair/regeneration. Finally, we show that survival can be extended without lessening CAW by titrating injected cell number.

CONCLUSIONS

Overall, this study describes a new model of CAW that could be useful for further studies of lung cancer-associated wasting and accompanying changes in the regenerative capacity of muscle. Additionally, this model addresses many recent concerns with existing models such as immunocompetence, tumor location, and survival time.

Drosophila as a model to understand autophagy deregulation in human disorders

Autophagy has important functions in normal physiology to maintain homeostasis and protect against cellular stresses by the removal of harmful cargos such as dysfunctional organelles, protein aggregates and invading pathogens. The deregulation of autophagy is a hallmark of many diseases and therapeutic targeting of autophagy is highly topical. With the complex role of autophagy in disease it is essential to understand the genetic and molecular basis of the contribution of autophagy to pathogenesis. The model organism, Drosophila, provides a genetically amenable system to dissect out the contribution of autophagy to human disease models. Here we review the roles of autophagy in human disease and how autophagy studies in Drosophila have contributed to the understanding of pathophysiology.

Exercise as an anti-inflammatory therapy for cancer cachexia: a focus on interleukin-6 regulation

Cancer cachexia is a complicated disorder of extreme, progressive skeletal muscle wasting. It is directed by metabolic alterations and systemic inflammation dysregulation. Numerous studies have demonstrated that increased systemic inflammation promotes this type of cachexia and have suggested that cytokines are implicated in the skeletal muscle loss. Exercise is firmly established as an anti-inflammatory therapy that can attenuate or even reverse the process of muscle wasting in cancer cachexia. The interleukin IL-6 is generally considered to be a key player in the development of the microenvironment of malignancy; it promotes tumor growth and metastasis by acting as a bridge between chronic inflammation and cancerous tissue and it also induces skeletal muscle atrophy and protein breakdown. Paradoxically, a beneficial role for IL-6 has also been identified recently, and that is its status as a “founding member” of the myokine class of proteins. Skeletal muscle is an important source of circulating IL-6 in people who participate in exercise training. IL-6 acts as an anti-inflammatory myokine by inhibiting TNFα and improving glucose uptake through the stimulation of AMPK signaling. This review discusses the action of IL-6 in skeletal muscle tissue dysfunction and the role of IL-6 as an “exercise factor” that modulates the immune system. This review also sheds light on the main considerations related to the treatment of muscle wasting in cancer cachexia.

Autocrine activin A signalling in ovarian cancer cells regulates secretion of interleukin 6, autophagy, and cachexia

BACKGROUND

The majority of patients with advanced cancer develop cachexia, a weight loss syndrome that severely reduces quality of life and limits survival. Our understanding of the underlying mechanisms that cause the condition is limited, and there are currently no treatment options that can completely reverse cachexia. Several tumour-derived factors and inflammatory mediators have been suggested to contribute to weight loss in cachectic patients. However, inconsistencies between studies are recurrent. Activin A and interleukin 6 (IL-6) are among the best studied factors that seem to be important, and several studies support their individual role in cachexia development.

METHODS

We investigated the interplay between activin A and IL-6 in the cachexia-inducing TOV21G cell line, both in culture and in tumours in mice. We previously found that the human TOV21G cells secrete IL-6 that induces autophagy in reporter cells and cachexia in mice. Using this established cachexia cell model, we targeted autocrine activin A by genetic, chemical, and biological approaches. The secretion of IL-6 from the cancer cells was determined in both culture and tumour-bearing mice by a species-specific ELISA. Autophagy reporter cells were used to monitor the culture medium for autophagy-inducing activities, and muscle mass changes were evaluated in tumour-bearing mice.

RESULTS

We show that activin A acts in an autocrine manner to promote the synthesis and secretion of IL-6 from cancer cells. By inhibiting activin A signalling, the production of IL-6 from the cancer cells is reduced by 40-50% (up to 42% reduction on protein level, P = 0.0048, and 48% reduction on mRNA level, P = 0.0308). Significantly reduced IL-6 secretion (P < 0.05) from the cancer cells is consistently observed when using biological, chemical, and genetic approaches to interfere with the autocrine activin A loop. Inhibiting activin signalling also reduces the ability of the cancer cells to accelerate autophagy in non-cancerous cells (up to 43% reduced autophagy flux, P = 0.0006). Coherent to the in vitro data, the use of an anti-activin receptor 2 antibody in cachectic tumour-bearing mice reduces serum levels of cancer cell-derived IL-6 by 62% (from 417 to 159 pg/mL, P = 0.03), and, importantly, it reverses cachexia and counteracts loss of all measured muscle groups (P < 0.0005).

CONCLUSIONS

Our data support a functional link between activin A and IL-6 signalling pathways and indicate that interference with activin A-induced IL-6 secretion from the tumour has therapeutic potential for cancer-induced cachexia.

Metastasis and cachexia: alongside in clinics, but not so in animal models

Cancer cachexia is a paraneoplastic syndrome characterized by lean mass wasting (with or without fat mass decrease), culminating in involuntary weight loss, which is the key clinical observation nowadays. There is a notable lack of studies involving animal models to mimic the clinical reality, which are mostly patients with cachexia and metastatic disease. This mismatch between the clinical reality and animal models could at least partly contribute to the poor translation observed in the field. In this paper, we retrieved and compared animal models used for cachexia research from 2017 and 10 years earlier (2007) and observed that very little has changed. Especially, clinically relevant models where cachexia is studied in an orthotopic or metastatic context were and still are very scarce. Finally, we described and supported the biological rationale behind why, despite technical challenges, these two phenomena-metastasis and cachexia-should be modelled in parallel, highlighting the overlapping pathways between them. To sum up, this review aims to contribute to rethinking and possibly switching the models currently used for cachexia research, to hopefully obtain better and more translational outcomes.