Z526 alleviates cancer cachexia-induced muscle and adipose inflammatory injury in vitro via suppression of macrophage...

Cancer cachexia is a multifactorial syndrome characterized by skeletal muscle wasting and adipose tissue atrophy. Our previous study showed that Z526 alleviated cancer cachexia-associated symptoms and reduced circulating inflammatory cytokine levels, suggesting that its effects may involve modulation of macrophage-associated inflammation. We therefore investigated the contribution of macrophages to cancer cachexia and the effects and underlying mechanisms of Z526. Compared with MC38 CM, C26 CM induced a stronger pro-inflammatory response in RAW264.7 cells, whereas RAW264.7/C26 co-culture supernatants contained higher TNF-α and IL-6 levels than supernatants from either cell type cultured alone. Conditioned medium from the RAW264.7/C26 co-culture also induced stronger activation of inflammation-associated signaling proteins, including MAPK, NF-κB, STAT3, and AMPK, in myotubes and adipocytes and caused more pronounced myotube atrophy and adipocyte lipolysis. Direct addition of Z526 to myotubes and adipocytes attenuated these cachexia-associated changes; this attenuation was accompanied by modulation of inflammation-responsive metabolic signaling pathways. In addition, conditioned medium from Z526-pretreated co-cultures caused less myotube atrophy and adipocyte lipolysis, and this protection was associated with reduced TNF-α and IL-6 levels in the conditioned medium. Mechanistically, Z526 reduced ROS accumulation and MAPK/NF-κB activation in macrophages stimulated with conditioned medium from cachexia-inducing tumor cells; these changes were accompanied by attenuated pro-inflammatory macrophage activation and reduced cytokine expression. Collectively, our findings support the involvement of cachexia-associated pro-inflammatory macrophage activation in tissue injury and suggest that the protective effects of Z526 may involve suppression of macrophage ROS-associated MAPK/NF-κB activation together with modulation of inflammatory signaling in muscle and adipose cells.