An integrative transcriptome study reveals Ddit4/Redd1 as a key regulator of cancer cachexia in rodent models

Transcriptomic signature of cancer cachexia by integration of machine learning, literature mining and meta-analysis

BACKGROUND

Cancer cachexia is a severe metabolic syndrome marked by skeletal muscle atrophy. A successful clinical intervention for cancer cachexia is currently lacking. The study of cachexia mechanisms is largely based on preclinical animal models and the availability of high-throughput transcriptomic datasets of cachectic mouse muscles is increasing through the extensive use of next generation sequencing technologies.

METHODS

Cachectic mouse muscle transcriptomic datasets of ten different studies were combined and mined by seven attribute weighting models, which analysed both categorical variables and numerical variables. The transcriptomic signature of cancer cachexia was identified by attribute weighting algorithms and was used to evaluate the performance of eleven pattern discovery models. The signature was employed to find the best combination of drugs (drug repurposing) for developing cancer cachexia treatment strategies, as well as to evaluate currently used cachexia drugs by literature mining.

RESULTS

Attribute weighting algorithms ranked 26 genes as the transcriptomic signature of muscle from mice with cancer cachexia. Deep Learning and Random Forest models performed better in differentiating cancer cachexia cases based on muscle transcriptomic data. Literature mining revealed that a combination of melatonin and infliximab has negative interactions with 2 key genes (Rorc and Fbxo32) upregulated in the transcriptomic signature of cancer cachexia in muscle.

CONCLUSIONS

The integration of machine learning, meta-analysis and literature mining was found to be an efficient approach to identifying a robust transcriptomic signature for cancer cachexia, with implications for improving clinical diagnosis and management of this condition.

Unlocking Prognostic Genes and Multi-Targeted Therapeutic Bioactives from Herbal Medicines to Combat Cancer-Associated Cachexia: A Transcriptomics and Network Pharmacology Approach

Cachexia is a devastating fat tissue and muscle wasting syndrome associated with every major chronic illness, including cancer, chronic obstructive pulmonary disease, kidney disease, AIDS, and heart failure. Despite two decades of intense research, cachexia remains under-recognized by oncologists. While numerous drug candidates have been proposed for cachexia treatment, none have achieved clinical success. Only a few drugs are approved by the FDA for cachexia therapy, but a very low success rate is observed among patients. Currently, the identification of drugs from herbal medicines is a frontier research area for many diseases. In this milieu, network pharmacology, transcriptomics, cheminformatics, and molecular docking approaches were used to identify potential bioactive compounds from herbal medicines for the treatment of cancer-related cachexia. The network pharmacology approach is used to select the 32 unique genes from 238 genes involved in cachexia-related pathways, which are targeted by 34 phytocompounds identified from 12 different herbal medicines used for the treatment of muscle wasting in many countries. Gene expression profiling and functional enrichment analysis are applied to decipher the role of unique genes in cancer-associated cachexia pathways. In addition, the pharmacological properties and molecular interactions of the phytocompounds were analyzed to find the target compounds for cachexia therapy. Altogether, combined omics and network pharmacology approaches were used in the current study to untangle the complex prognostic genes involved in cachexia and phytocompounds with anti-cachectic efficacy. However, further functional and experimental validations are required to confirm the efficacy of these phytocompounds as commercial drug candidates for cancer-associated cachexia.

Females display relatively preserved muscle quality compared with males during the onset and early stages of C26-induced cancer cachexia

Cancer cachexia is clinically defined by involuntary weight loss >5% in <6 mo, primarily affecting skeletal muscle. Here, we aimed to identify sex differences in the onset of colorectal cancer cachexia with specific consideration to skeletal muscle contractile and metabolic functions. Eight-weeks old BALB/c mice (69 males, 59 females) received subcutaneous C26 allografts or PBS vehicle. Tumors were developed for 10-, 15-, 20-, or 25 days. Muscles and organs were collected, in vivo muscle contractility, protein synthesis rate, mitochondrial function, and protein turnover markers were assessed. One-way ANOVA within sex and trend analysis between sexes were performed, P < 0.05. Gastrocnemius and tibialis anterior (TA) muscles became atrophic in male mice at 25 days, whereas female mice exhibited no significant differences in muscle weights at endpoints despite presenting hallmarks of cancer cachexia (fat loss, hepatosplenomegaly). We observed lowered muscle contractility and protein synthesis concomitantly to muscle mass decay in males, with higher proteolytic markers in muscles of both sexes. mRNA of Opa1 was lower in TA, whereas Bnip3 was higher in gastrocnemius after 25 days in male mice, with no significant effect in female mice. Our data suggest relative protections to skeletal muscle in females compared with males despite other canonical signs of cancer cachexia and increased protein degradation markers; suggesting we should place onus upon nonmuscle tissues during early stages of cancer cachexia in females. We noted potential protective mechanisms relating to skeletal muscle contractile and mitochondrial functions. Our findings underline possible heterogeneity in onset of cancer cachexia between biological sexes, suggesting the need for sex-specific approaches to treat cancer cachexia.NEW & NOTEWORTHY Our study demonstrates biological-sex differences in phenotypic characteristics of cancer cachexia between male and female mice, whereby females display many common characteristics of cachexia (gonadal fat loss and hepatosplenomegaly), protein synthesis markers alterations, and common catabolic markers in skeletal muscle despite relatively preserved muscle mass in early-stage cachexia compared with males. Mechanisms of cancer cachexia appear to differ between sexes. Data suggest need to place onus of early cancer cachexia detection and treatment on nonmuscle tissues in females.

The time-course of cancer cachexia onset reveals biphasic transcriptional disruptions in female skeletal muscle distinct from males

BACKGROUND

Cancer-cachexia (CC) is a debilitating condition affecting up to 80% of cancer patients and contributing to 40% of cancer-related deaths. While evidence suggests biological sex differences in the development of CC, assessments of the female transcriptome in CC are lacking, and direct comparisons between sexes are scarce. This study aimed to define the time course of Lewis lung carcinoma (LLC)-induced CC in females using transcriptomics, while directly comparing biological sex differences.

RESULTS

We found the global gene expression of the gastrocnemius muscle of female mice revealed biphasic transcriptomic alterations, with one at 1 week following tumor allograft and another during the later stages of cachexia development. The early phase was associated with the upregulation of extracellular-matrix pathways, while the later phase was characterized by the downregulation of oxidative phosphorylation, electron transport chain, and TCA cycle. When DEGs were compared to a known list of mitochondrial genes (MitoCarta), ~ 47% of these genes were differently expressed in females exhibiting global cachexia, suggesting transcriptional changes to mitochondrial gene expression happens concomitantly to functional impairments previously published. In contrast, the JAK-STAT pathway was upregulated in both the early and late stages of CC. Additionally, we observed a consistent downregulation of Type-II Interferon signaling genes in females, which was associated with protection in skeletal muscle atrophy despite systemic cachexia. Upregulation of Interferon signaling was noted in the gastrocnemius muscle of cachectic and atrophic male mice. Comparison of female tumor-bearing mice with males revealed ~ 70% of DEGs were distinct between sexes in cachectic animals, demonstrating dimorphic mechanisms of CC.

CONCLUSION

Our findings suggest biphasic disruptions in the transcriptome of female LLC tumor-bearing mice: an early phase associated with ECM remodeling and a late phase, accompanied by the onset of systemic cachexia, affecting overall muscle energy metabolism. Notably, ~ 2/3 of DEGs in CC are biologically sex-specific, providing evidence of dimorphic mechanisms of cachexia between sexes. Downregulation of Type-II Interferon signaling genes appears specific to CC development in females, suggesting a new biological sex-specific marker of CC not reliant on the loss of muscle mass, that might represent a protective mechanism against muscle loss in CC in female mice.

Nanocarbon-Enforced Anisotropic MusCAMLR for Rapid Rescue of Mechanically Damaged Skeletal Muscles

Mechanical damages to skeletal muscles could be detrimental to the active work hours and lifestyle of athletes, mountaineers, and security personnel. In this regard, the slowness of conventional treatment strategies and drug-associated side effects greatly demand the design and development of novel biomaterials, which can rescue such mechanically damaged skeletal muscles. To accomplish this demand, we have developed a musculoresponsive polymer-carbon composite for assisting myotubular regeneration (MusCAMLR). The MusCAMLR is enforced to attain anisotropic muscle-like characteristics while incorporating a smartly passivated nanoscale carbon material in the PNIPAM gel under physiological conditions as a stimulus, which is not achieved by the pristine nanocarbon system. The MusCAMLR establishes a specific mechanical interaction with muscle cells, supports myotube regeneration, maintains excellent mechanical similarity with the myotube, and restores the structural integrity and biochemical parameters of mechanically damaged muscles in a delayed onset muscle soreness (DOMS) rat model within a short period of 72 h. Concisely, this study discloses the potential of smartly passivated nanocarbon in generating an advanced biomaterial system, MusCAMLR, from a regularly used polymeric hydrogel system. This engineered polymer-carbon composite reveals its possible potential to be used as a nondrug therapeutic alternative for rescuing mechanically damaged muscles and probably can be extended for therapy of various other diseases including muscular dystrophy.

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.

Cancer Cachexia: Signaling and Transcriptional Regulation of Muscle Catabolic Genes

Simple Summary

An uncontrollable loss in the skeletal muscle of cancer patients which leads to a significant reduction in body weight is clinically referred to as cancer cachexia (CC). While factors derived from the tumor environment which trigger various signaling pathways have been identified, not much progress has been made clinically to effectively prevent muscle loss. Deeper insights into the transcriptional and epigenetic regulation of muscle catabolic genes may shed light on key regulators which can be targeted to develop new therapeutic avenues.

Abstract

Cancer cachexia (CC) is a multifactorial syndrome characterized by a significant reduction in body weight that is predominantly caused by the loss of skeletal muscle and adipose tissue. Although the ill effects of cachexia are well known, the condition has been largely overlooked, in part due to its complex etiology, heterogeneity in mediators, and the involvement of diverse signaling pathways. For a long time, inflammatory factors have been the focus when developing therapeutics for the treatment of CC. Despite promising pre-clinical results, they have not yet advanced to the clinic. Developing new therapies requires a comprehensive understanding of how deregulated signaling leads to catabolic gene expression that underlies muscle wasting. Here, we review CC-associated signaling pathways and the transcriptional cascade triggered by inflammatory cytokines. Further, we highlight epigenetic factors involved in the transcription of catabolic genes in muscle wasting. We conclude with reflections on the directions that might pave the way for new therapeutic approaches to treat CC.

Nutritional Sensor REDD1 in Cancer and Inflammation: Friend or Foe?

Regulated in Development and DNA Damage Response 1 (REDD1)/DNA Damage-Induced Transcript 4 (DDIT4) is an immediate early response gene activated by different stress conditions, including growth factor depletion, hypoxia, DNA damage, and stress hormones, i.e., glucocorticoids. The most known functions of REDD1 are the inhibition of proliferative signaling and the regulation of metabolism via the repression of the central regulator of these processes, the mammalian target of rapamycin (mTOR). The involvement of REDD1 in cell growth, apoptosis, metabolism, and oxidative stress implies its role in various pathological conditions, including cancer and inflammatory diseases. Recently, REDD1 was identified as one of the central genes mechanistically involved in undesirable atrophic effects induced by chronic topical and systemic glucocorticoids widely used for the treatment of blood cancer and inflammatory diseases. In this review, we discuss the role of REDD1 in the regulation of cell signaling and processes in normal and cancer cells, its involvement in the pathogenesis of different diseases, and the approach to safer glucocorticoid receptor (GR)-targeted therapies via a combination of glucocorticoids and REDD1 inhibitors to decrease the adverse atrophogenic effects of these steroids.

TXNIP inhibits the progression of osteosarcoma through DDIT4-mediated mTORC1 suppression

Osteosarcoma (OS) is the most common primary malignant bone tumor in adolescents and children. The pathogenesis of this disease is complex and the mechanisms involved have not been fully elucidated. Thioredoxin-interacting protein (TXNIP), as a member of the α-rhodopsin inhibitory protein family, can combine with thioredoxin to inhibit its antioxidant function. This process inhibits glucose absorption and metabolic rearrangement necessary for the regulation of cellular growth. In recent years, TXNIP has emerged as a new candidate target for tumors. However, the biological function and role of TXNIP in OS remains unclear. This study confirmed the low expression of TXNIP in OS tissues and cells, which was significantly related to the poor survival rate and clinical characteristics of patients with OS. Various cell phenotype experiments have shown that TXNIP inhibits the proliferation, migration, and invasion of OS cells, and promotes their apoptosis. Further studies found that the tumor suppressor effect of TXNIP was mediated by upregulating DNA damage-inducible transcript 4 (DDIT4) and inhibiting the phosphorylation of mechanistic target of rapamycin complex 1 (mTORC1) downstream substrate S6. Based on the above, our study explored the key role of TXNIP/DDIT4/mTORC1 suppression as a regulatory axis in the progression of OS, and laid the foundation for precise targeted therapy for OS.

Tumor cell anabolism and host tissue catabolism-energetic inefficiency during cancer cachexia

Cancer-associated cachexia (CC) is a pathological condition characterized by sarcopenia, adipose tissue depletion, and progressive weight loss. CC is driven by multiple factors such as anorexia, excessive catabolism, elevated energy expenditure by growing tumor mass, and inflammatory mediators released by cancer cells and surrounding tissues. In addition, endocrine system, systemic metabolism, and central nervous system (CNS) perturbations in combination with cachexia mediators elicit exponential elevation in catabolism and reduced anabolism in skeletal muscle, adipose tissue, and cardiac muscle. At the molecular level, mechanisms of CC include inflammation, reduced protein synthesis, and lipogenesis, elevated proteolysis and lipolysis along with aggravated toxicity and complications of chemotherapy. Furthermore, CC is remarkably associated with intolerance to anti-neoplastic therapy, poor prognosis, and increased mortality with no established standard therapy. In this context, we discuss the spatio-temporal changes occurring in the various stages of CC and highlight the imbalance of host metabolism. We provide how multiple factors such as proteasomal pathways, inflammatory mediators, lipid and protein catabolism, glucocorticoids, and in-depth mechanisms of interplay between inflammatory molecules and CNS can trigger and amplify the cachectic processes. Finally, we highlight current diagnostic approaches and promising therapeutic interventions for CC.

The myokine Fibcd1 is an endogenous determinant of myofiber size and mitigates cancer-induced myofiber atrophy

Decline in skeletal muscle cell size (myofiber atrophy) is a key feature of cancer-induced wasting (cachexia). In particular, atrophy of the diaphragm, the major muscle responsible for breathing, is an important determinant of cancer-associated mortality. However, therapeutic options are limited. Here, we have used Drosophila transgenic screening to identify muscle-secreted factors (myokines) that act as paracrine regulators of myofiber growth. Subsequent testing in mouse myotubes revealed that mouse Fibcd1 is an evolutionary-conserved myokine that preserves myofiber size via ERK signaling. Local administration of recombinant Fibcd1 (rFibcd1) ameliorates cachexia-induced myofiber atrophy in the diaphragm of mice bearing patient-derived melanoma xenografts and LLC carcinomas. Moreover, rFibcd1 impedes cachexia-associated transcriptional changes in the diaphragm. Fibcd1-induced signaling appears to be muscle selective because rFibcd1 increases ERK activity in myotubes but not in several cancer cell lines tested. We propose that rFibcd1 may help reinstate myofiber size in the diaphragm of patients with cancer cachexia.

Aging Aggravates Cachexia in Tumor-Bearing Mice

Simple Summary

Cachexia is a deadly disease that accompanies many different types of cancers. Animal studies on cachexia have so far mostly been conducted using young mice, while cancer in humans is a disease of high age. Mouse models used to date may therefore not be suitable to study cachexia with relevance to patients. By comparing young and old mice of three different strains and two different tumor types, we here show that the age of mice has a substantial effect on cachexia progression (specifically body weight, tissue weight, fiber size, molecular markers) that is dependent on the mouse strain studied. This is independent of glucose tolerance. The cachexia markers IL6 and GDF15 differ between ages in both mice and patients. Future studies on cachexia should consider the age and strain of mice.

Abstract

Background: Cancer is primarily a disease of high age in humans, yet most mouse studies on cancer cachexia are conducted using young adolescent mice. Given that metabolism and muscle function change with age, we hypothesized that aging may affect cachexia progression in mouse models. Methods: We compare tumor and cachexia development in young and old mice of three different strains (C57BL/6J, C57BL/6N, BALB/c) and with two different tumor cell lines (Lewis Lung Cancer, Colon26). Tumor size, body and organ weights, fiber cross-sectional area, circulating cachexia biomarkers, and molecular markers of muscle atrophy and adipose tissue wasting are shown. We correlate inflammatory markers and body weight dependent on age in patients with cancer. Results: We note fundamental differences between mouse strains. Aging aggravates weight loss in LLC-injected C57BL/6J mice, drives it in C57BL/6N mice, and does not influence weight loss in C26-injected BALB/c mice. Glucose tolerance is unchanged in cachectic young and old mice. The stress marker GDF15 is elevated in cachectic BALB/c mice independent of age and increased in old C57BL/6N and J mice. Inflammatory markers correlate significantly with weight loss only in young mice and patients. Conclusions: Aging affects cachexia development and progression in mice in a strain-dependent manner and influences the inflammatory profile in both mice and patients. Age is an important factor to consider for future cachexia studies.

Low-Dose Metformin as a Monotherapy Does Not Reduce Non-Small-Cell Lung Cancer Tumor Burden in Mice

Non-small-cell lung cancer (NSCLC) makes up 80-85% of lung cancer diagnoses. Lung cancer patients undergo surgical procedures, chemotherapy, and/or radiation. Chemotherapy and radiation can induce deleterious systemic side effects, particularly within skeletal muscle. To determine whether metformin reduces NSCLC tumor burden while maintaining skeletal muscle health, C57BL/6J mice were injected with Lewis lung cancer (LL/2), containing a bioluminescent reporter for in vivo tracking, into the left lung. Control and metformin (250 mg/kg) groups received treatments twice weekly. Skeletal muscle was analyzed for changes in genes and proteins related to inflammation, muscle mass, and metabolism. The LL/2 model effectively mimics lung cancer growth and tumor burden. The in vivo data indicate that metformin as administered was not associated with significant improvement in tumor burden in this immunocompetent NSCLC model. Additionally, metformin was not associated with significant changes in key tumor cell division and inflammation markers, or improved skeletal muscle health. Metformin treatment, while exhibiting anti-neoplastic characteristics in many cancers, appears not to be an appropriate monotherapy for NSCLC tumor growth in vivo. Future studies should pursue co-treatment modalities, with metformin as a potentially supportive drug rather than a monotherapy to mitigate cancer progression.

REDD1 deletion attenuates cancer cachexia in mice

Cancer cachexia is a wasting disorder associated with advanced cancer that contributes to mortality. Cachexia is characterized by involuntary loss of body weight and muscle weakness that affects physical function. Regulated in DNA damage and development 1 (REDD1) is a stress-response protein that is transcriptionally upregulated in muscle during wasting conditions and inhibits mechanistic target of rapamycin complex 1 (mTORC1). C2C12 myotubes treated with Lewis lung carcinoma (LLC)-conditioned media increased REDD1 mRNA expression and decreased myotube diameter. To investigate the role of REDD1 in cancer cachexia, we inoculated 12-week old male wild-type or global REDD1 knockout (REDD1 KO) mice with LLC cells and euthanized 28-days later. Wild-type mice had increased skeletal muscle REDD1 expression, and REDD1 deletion prevented loss of body weight and lean tissue mass, but not fat mass. We found that REDD1 deletion attenuated loss of individual muscle weights and loss of myofiber cross sectional area. We measured markers of the Akt/mTORC1 pathway and found that, unlike wild-type mice, phosphorylation of both Akt and 4E-BP1 was maintained in the muscle of REDD1 KO mice after LLC inoculation, suggesting that loss of REDD1 is beneficial in maintaining mTORC1 activity in mice with cancer cachexia. We measured Foxo3a phosphorylation as a marker of the ubiquitin proteasome pathway and autophagy and found that REDD1 deletion prevented dephosphorylation of Foxo3a in muscles from cachectic mice. Our data provides evidence that REDD1 plays an important role in cancer cachexia through the regulation of both protein synthesis and protein degradation pathways.