Myokines related to leukocyte recruitment are down-regulated in osteosarcoma

Myokines are cytokines that are secreted by muscle cells during exercises, muscle development and pathology. Studies have shown that expression of some individual myokines was altered in tumors. However, comprehensive analyses of myokines' expression in osteosarcoma (OS), the most common malignant tumor in musculoskeletal system, have not been performed. In this study, we analyzed the expression of 35 myokines in osteosarcoma, peritumoral skeletal muscle, and cancellous bone by qRT-PCR. Heatmap analysis based on the expression pattern of these myokines revealed that OS is more likely derived from cancellous bone than peritumoral skeletal muscle. Thus, we compared the expression of myokines between OS and cancellous bone to reveal a potential role of myokines in OS development. Our results showed that expression of 19 myokines in OS was significantly lower than that in cancellous bone. KEGG signaling pathway analysis showed that these 19 myokines are involved in several important signaling pathways, one of which was associated with leukocyte recruitment in TNF-α signaling. We verified that expression of these leukocyte recruitment-related myokines were down-regulated in OS cell line MNNG compared to those in human BMSC. Downregulation of the myokines related to leukocyte recruitment suggests that escaping from host immune system may help the occurrence of osteosarcoma.