Identification of oncostatin M target genes by RNA-seq in mouse primary myotube cells

Cancer cachexia is a debilitating wasting syndrome marked by inflammation and loss of adipose and skeletal muscle tissues. While about 20% of cancer deaths are caused by cachexia, there are no effective treatments available, and molecular mechanisms underlying cancer cachexia remain elusive. Oncostatin M, belonging to the gp130/IL6 cytokine family, is mainly released by macrophages, monocytes, and T-cells and exert pleiotropic activities in cell differentiation, proliferation, and inflammatory network. In various cell and cancer types, OSM was paradoxically reported to both promote and inhibit inflammation. Even though cytokine IL-6 is known to be associated with muscle atrophy, the functional significance of cytokine OSM in skeletal muscle cells is poorly understood. The advent of high-throughput sequencing technologies presented an unprecedented approach to study RNA. Therefore, it has become the prime choice to characterize and quantify cell transcripts. Here, we aim to investigate tumor signaling to muscle tissue by identifying cytokine Oncostatin M target genes in skeletal muscle cells using high- throughput RNA sequencing (RNA-seq) technology. Using "Tailored Pipeline," we have analyzed IL6 family cytokines, specifically OSM, IL6 and, LIF. We treated mouse primary myotube cells with these cytokines and deciphered the differentially expressed genes that were significantly up-and down-regulated and show association with muscle atrophy. RNA sequencing showed widespread alterations in cytokine treated samples compared to control samples, with the largest differences in OSM treated samples compared to other conditions. OSM significantly induced muscle atrophy-related genes such as Ampd3, Sln, Murf-1, Atrogin-1, and Serpina3n. Consistent with this, these signature genes were validated using qRT-PCR. GSEA analysis revealed that top commonly enriched pathways include hypoxia, inflammatory response pathway, glycolysis, and IL6-JAK-STAT3 pathways. These results provide a global view of OSM, IL6, and LIF expression responses in mouse primary myotube cells with cytokine-specific response patterns. Our results suggest these cytokines may use similar signaling mechanisms in mouse primary myotube cells. Compared to IL6 and LIF, OSM potently promotes cellular atrophy in cultured myotubes. Elucidating cytokine-induced mechanisms may establish potential therapeutic targets for the treatment of the cachectic syndrome. Our findings support an important role for OSM in cellular muscle atrophy and suggest that OSM could be targeted as a novel factor in fighting cachexia associated with cancer or other chronic diseases.