Amelioration of muscle wasting by gintonin in cancer cachexia

The role of microRNAs in dexamethasone-induced skeletal muscle atrophy

Muscle atrophy is characterized by a decrease in muscle mass, strength, and activity. Recently, it was determined that microRNAs (miRNAs) can regulate muscle atrophy and that dexamethasone (Dex), an allergy and autoimmune disorder treatment that can induce muscle atrophy. Therefore, this study was designed to identify miRNAs expressed in Dex-induced muscle atrophy in mice using small RNA sequencing. A total of 820 miRNAs were identified, with 58 miRNAs expressed explicitly in atrophic muscles. Dex-induced muscle atrophy miRNAs clustered separately from the differential miRNAs in aging, disuse, and cancer-induced muscle atrophy models. The target genes of Dex-induced muscle atrophy miRNAs were independently enriched in inositol phosphate metabolism, hypoxia-inducible factor-1 signaling pathway, etc. Of note, there was a significant increase in the volume of fat cells and adipose weight in the Dex group, suggesting that fat deposition during Dex-induced skeletal muscle atrophy is a unique and typical feature. SIMPLE SUMMARY: Dexamethasone (Dex) is a glucocorticoid used to treat allergic and autoimmune diseases, but excessive use can lead to skeletal muscle atrophy. We used dexamethasone (Dex) to build a muscle atrophy model in mice, and obvious changes had taken place in mouse body weight, muscle tissue morphology and related genes. A large number of microRNAs were found to be differentially expressed, and their functions were enriched in pathways related to muscle development. At the same time, we compared the similarities and differences of microRNAs and their functions between Dex induced muscle atrophy model and other muscle atrophy models. Finally, we were surprised to find that Dex induced muscle atrophy is specifically accompanied by the accumulation of body fat.

Adipose-derived small extracellular vesicle miR-146a-5p targets Fbx32 to regulate mitochondrial autophagy and delay aging in skeletal muscle

This study investigates how miR-146a-5p, found in adipose tissue-derived small extracellular vesicles (sEV), influences mitochondrial autophagy and its impact on delaying skeletal muscle aging through the targeting of Fbx32. The findings highlight miR-146a-5p as crucial in skeletal muscle development and aging, influencing autophagy, apoptosis, differentiation, and proliferation, collectively impacting muscle atrophy. In C2C12 cells, miR-146a-5p mimics decreased apoptosis, autophagy, and reactive oxygen species (ROS) levels, while enhancing ATP production; conversely, miR-146a-5p inhibitors had the opposite effects. Furthermore, miR-146a-5p-enriched sEV from adipose tissue alleviated skeletal muscle atrophy in aged mice and promoted muscle fiber growth and repair by regulating mitochondrial autophagy and apoptosis. Mechanistically, miR-146a-5p modulated mitochondrial autophagy in myoblasts by targeting Fbx32 and impacting the FoxO3 signaling pathway. This led to a notable decrease in apoptosis-related gene expression, reduced ROS production, and elevated ATP levels. In conclusion, miR-146a-5p derived from WAT-sEV modulates myoblast autophagy, apoptosis, ROS, and differentiation through the Fbx32/FoxO3 signaling axis. This work presents a novel molecular target and theoretical framework for delaying skeletal muscle aging and developing therapies for skeletal muscle-related disorders.

Plant-Derived Treatments for Different Types of Muscle Atrophy

With the development of medicine and chemistry, an increasing number of plant-derived medicines have been shown to exert beneficial therapeutic on the treatment of various physical and psychological diseases. In particular, by using physical chemistry methods, we are able to examine the chemical components of plants and the effects of these substances on the human body. Muscle atrophy (MA) is characterized by decreased muscle mass and function, is caused by multiple factors and severely affects the quality of life of patients. The multifactorial and complex pathogenesis of MA hinders drug research and disease treatment. However, phytotherapy has achieved significant results in the treatment of MA. We searched PubMed and the Web of Science for articles related to plant-derived substances and muscle atrophy. After applying exclusion and inclusion criteria, 166 and 79 articles met the inclusion criteria, respectively. A total of 173 articles were included in the study after excluding duplicates. The important role of phytoactives such as curcumin, resveratrol, and ginsenosides in the treatment of MA (e.g., maintaining a positive nitrogen balance in muscles and exerting anti-inflammatory and antioxidant effects) has been extensively studied. Unfortunately, MA dose not have to a single cause, and each cause has its own unique mechanism of injury. This review focuses on the therapeutic mechanisms of active plant components in MA and provides insights into the personalized treatment of MA.

Gintonin Stimulates Glucose Uptake in Myocytes: Involvement of Calcium and Extracellular Signal-Regulated Kinase Signaling

Ginseng has anti-hyperglycemic effects. Gintonin, a glycolipoprotein derived from ginseng, also stimulates insulin release from pancreatic beta cells. However, the role of gintonin in glucose metabolism within skeletal muscle is unknown. Here, we showed the effect of gintonin on glucose uptake, glycogen content, glucose transporter (GLUT) 4 expression, and adenosine triphosphate (ATP) content in C2C12 myotubes. Gintonin (3-30 μg/mL) dose-dependently stimulated glucose uptake in myotubes. The expression of GLUT4 on the cell membrane was increased by gintonin treatment. Treatment with 1-3 μg/mL of gintonin increased glycogen content in myotubes, but the content was decreased at 30 μg/mL of gintonin. The ATP content in myotubes increased following treatment with 10-100 μg/mL gintonin. Gintonin transiently elevated intracellular calcium concentrations and increased the phosphorylation of extracellular signal-regulated kinase (ERK). Gintonin-induced transient calcium increases were inhibited by treatment with the lysophosphatidic acid receptor inhibitor Ki16425, the phospholipase C inhibitor U73122, and the inositol 1,4,5-trisphosphate receptor antagonist 2-aminoethoxydiphenyl borate. Gintonin-stimulated glucose uptake was decreased by treatment with U73122, the intracellular calcium chelator 1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid tetra(acetoxymethyl) ester, and the ERK inhibitor PD98059. These results show that gintonin plays a role in glucose metabolism by increasing glucose uptake through transient calcium increases and ERK signaling pathways. Thus, gintonin may be beneficial for glucose metabolism control.

Molecular Mechanisms of Cachexia: A Review

Cachexia is a condition characterized by substantial loss of body weight resulting from the depletion of skeletal muscle and adipose tissue. A considerable fraction of patients with advanced cancer, particularly those who have been diagnosed with pancreatic or gastric cancer, lung cancer, prostate cancer, colon cancer, breast cancer, or leukemias, are impacted by this condition. This syndrome manifests at all stages of cancer and is associated with an unfavorable prognosis. It heightens the susceptibility to surgical complications, chemotherapy toxicity, functional impairments, breathing difficulties, and fatigue. The early detection of patients with cancer cachexia has the potential to enhance both their quality of life and overall survival rates. Regarding this matter, blood biomarkers, although helpful, possess certain limitations and do not exhibit universal application. Additionally, the available treatment options for cachexia are currently limited, and there is a lack of comprehensive understanding of the underlying molecular pathways associated with this condition. Thus, this review aims to provide an overview of molecular mechanisms associated with cachexia and potential therapeutic targets for the development of effective treatments for this devastating condition.

Advances in research on cell models for skeletal muscle atrophy

Skeletal muscle, the largest organ in the human body, plays a crucial role in supporting and defending the body and is essential for movement. It also participates in regulating the processes of protein synthesis and degradation. Inhibition of protein synthesis and activation of degradation metabolism can both lead to the development of skeletal muscle atrophy, a pathological condition characterized by a decrease in muscle mass and fiber size. Many physiological and pathological conditions can cause a decline in muscle mass, but the underlying mechanisms of its pathogenesis remain incompletely understood, and the selection of treatment strategies and efficacy evaluations vary. Moreover, the early symptoms of this condition are often not apparent, making it easily overlooked in clinical practice. Therefore, it is necessary to develop and use cell models to understand the etiology and influencing factors of skeletal muscle atrophy. In this review, we summarize the methods used to construct skeletal muscle cell models, including hormone, inflammation, cachexia, genetic engineering, drug, and physicochemical models. We also analyze, compare, and evaluate the various construction and assessment methods.

Cancer cachexia: molecular mechanisms and treatment strategies

Muscle wasting is a consequence of physiological changes or a pathology characterized by increased catabolic activity that leads to progressive loss of skeletal muscle mass and strength. Numerous diseases, including cancer, organ failure, infection, and aging-associated diseases, are associated with muscle wasting. Cancer cachexia is a multifactorial syndrome characterized by loss of skeletal muscle mass, with or without the loss of fat mass, resulting in functional impairment and reduced quality of life. It is caused by the upregulation of systemic inflammation and catabolic stimuli, leading to inhibition of protein synthesis and enhancement of muscle catabolism. Here, we summarize the complex molecular networks that regulate muscle mass and function. Moreover, we describe complex multi-organ roles in cancer cachexia. Although cachexia is one of the main causes of cancer-related deaths, there are still no approved drugs for cancer cachexia. Thus, we compiled recent ongoing pre-clinical and clinical trials and further discussed potential therapeutic approaches for cancer cachexia.

miR-27b-3p Attenuates Muscle Atrophy by Targeting Cbl-b in Skeletal Muscles

As it is well known, muscle atrophy is a process in which protein degradation increases and protein synthesis decreases. This process is regulated by a variety of links. Among them, microRNAs play an essential role in this process, which has attracted widespread attention. In this paper, we find that miR-27b-3p and Cbl-b genes are significantly differentially expressed in the induced atrophy model. The dual-luciferase experiment and Western blot analysis confirmed that miR-27b-3p could regulate the expression of Cbl-b. In C2C12-differentiated myotubes, the overexpression of the Cbl-b gene showed that Cbl-b could upregulate the expression of MuRF-1 and Atrogin-1, which are related marker genes of muscle atrophy, at both the mRNA and protein levels, indicating that the Cbl-b gene can specifically affect muscle atrophy. The knockdown of the Cbl-b gene after C2C12-differentiated myotubes induced atrophy treatment can downregulate the expression of muscle-atrophy-related genes, indicating that manual intervention to downregulate the expression of Cbl-b has a certain alleviating effect on muscle atrophy. These data suggest that miR-27b-3p can regulate the expression of the Cbl-b gene and then exert a particular influence on muscle atrophy through the Cbl-b gene.