Decreased miR-497-5p Suppresses IL-6 Induced Atrophy in Muscle Cells

Abstract

Interleukin-6 (IL-6) is a pro-inflammatory cytokine associated with skeletal muscle wasting in cancer cachexia. The control of gene expression by microRNAs (miRNAs) in muscle wasting involves the regulation of thousands of target transcripts. However, the miRNA-target networks associated with IL6-induced muscle atrophy remain to be characterized. Here, we show that IL-6 promotes the atrophy of C2C12 myotubes and changes the expression of 20 miRNAs (5 up-regulated and 15 down-regulated). Gene Ontology analysis of predicted miRNAs targets revealed post-transcriptional regulation of genes involved in cell differentiation, apoptosis, migration, and catabolic processes. Next, we performed a meta-analysis of miRNA-published data that identified miR-497-5p, a down-regulated miRNAs induced by IL-6, also down-regulated in other muscle-wasting conditions. We used miR-497-5p mimics and inhibitors to explore the function of miR-497-5p in C2C12 myoblasts and myotubes. We found that miR-497-5p can regulate the expression of the cell cycle genes CcnD2 and CcnE1 without affecting the rate of myoblast cellular proliferation. Notably, miR-497-5p mimics induced myotube atrophy and reduced Insr expression. Treatment with miR-497-5p inhibitors did not change the diameter of the myotubes but increased the expression of its target genes Insr and Igf1r. These genes are known to regulate skeletal muscle regeneration and hypertrophy via insulin-like growth factor pathway and were up-regulated in cachectic muscle samples. Our miRNA-regulated network analysis revealed a potential role for miR-497-5p during IL6-induced muscle cell atrophy and suggests that miR-497-5p is likely involved in a compensatory mechanism of muscle atrophy in response to IL-6.

The complex pathophysiology of cardiac cachexia: A review of current pathophysiology and implications for clinical practice

“…75 The combination of nutritional support and aerobic exercise should be provided as it might be appropriate to manage CC symptoms. This is because dietary support; high calories and protein supplements, help to compensate excessive catabolism and build the muscle 76 while the latter restores the proteasome overactivation and protect the oxidation stress and UPS overactivation 77 as bowel oedema can be decreased with improved food Fish oil-omega-3 polyunsaturated fatty acids; PUFA-, containing rich protein, rich calories, nutritional supplements and important amino acid have been used in CC patients 80 and shown to reduce TNF-α. 81 PUFA together with BCAA have potential benefits but extensive evidence is currently lacking.…”

Muscle and Bone Defects in Metastatic Disease

“…Mechanistically, overexpression of miR-203 resulted in suppressed proliferation and stimulated apoptosis of skeletal muscle cells via targeting BIRC5 (survivin), a negative regulator of apoptosis. While miR-181a-3p and both miR-195a-5p and miR-125b-1-3p induced muscle atrophy by activating apoptotic signaling pathways [61,62], a decrease in miR-497-5p mediated by IL-6, counteracted muscle atrophy by stimulating expression of hypertrophy-related genes in cancer cachexia [63]. Furthermore, miR-450-5p and miR-451a were found differentially expressed in skeletal muscle of cachectic lung cancer patients; however, more research is needed to better understand their regulation in muscle atrophy [64].…”

What Role Do Inflammatory Cytokines Play in Cancer Cachexia?

“…IL-6 is a soluble pleiotropic IL involved in both anabolic and catabolic pathways. Over 100 ng/mL physiological level is required to participate in catabolic ways [3]. Along with IL-6, TNF-α, also named cachectin, IL-1-beta, and IFN-γ activate the NF-κB pathway, promote the transcription of ubiquitin-proteasome E3 ligase [19,20], and responsible for muscle proteolysis NF-κB is upregulated rapidly in the nucleus [4].…”

“…Cancer cachexia is a complex multifactorial syndrome that affects about half of cancer patients and threefourths of those with advanced cancer [3][4][5]. They are also responsible for one-fourth of the deaths in cancer patients [6][7][8].…”

“…Cancer cachexia is usually diagnosed only after a weight loss of 7-15% [ 3 ] and decreases the quality of a patient’s life. It is screened considering various factors such as weight loss in the last six months, upper arm circumference, triceps skinfold thickness, strength in the handgrip, C-reactive protein (CRP) levels, and screening tools such as malnutrition universal screening tool (MUST) [ 12 ].…”