Inhibition of HSP90 reversed STAT3 mediated muscle wasting induced by cancer cachexia

Cancer cachexia is one of the most common causes of death among cancer patients, no effective anti-cachectic treatment that is currently available. In experimental cachectic models, aberrant activation of STAT3 in skeletal muscle has been found contribute to muscle wasting. However, its clinical association, the factors regulating STAT3 activation and the molecular mechanisms of STAT3-induced muscle atrophy in cancer cachexia remain incompletely understood. Here, we show that there are the enhanced interaction between STAT3 and HSP90, that cause the persistent STAT3 activation in the skeletal muscle of cancer cachexia patients, are the crucial event for the development of cachectic muscle wasting. Administration of HSP90 inhibitors alleviated the muscle wasting in C26 tumor bearing cachetic mice model or C26 conditional medium induced C2C12 myotube atrophy. A mechanistic study indicated that in cachectic skeletal muscle, prolonged STAT3 activation triggered muscle wasting in a FOXO1-dependent manner, STAT3 activated FOXO1 by binding directly to its promoter. Our results provide key insights into the role of the HSP90/STAT3/FOXO1 axis in cachectic muscle wasting, which shows promising therapeutic potential as a target for the treatment of cancer cachexia.