HCT116 colorectal liver metastases exacerbate muscle wasting in a mouse model for the study of colorectal cancer cachexia

Abstract

Colorectal cancer (CRC) is often accompanied by formation of liver metastases (LM) and skeletal muscle (SkM) wasting, i.e. cachexia. Despite affecting the majority of CRC patients, cachexia remains underserved, understudied, and uncured. Animal models for the study of CRC-induced cachexia, in particular models containing LM are sparse, thus we aimed to characterize two new models of CRC cachexia. Male NSG mice were injected subcutaneously (HCT116) or intrasplenically with human HCT116 CRC tumor cells to disseminate LM (mHCT116), while experimental controls received saline (n= 5-8/group). Tumor growth was accompanied by loss of SkM mass (HCT116: −20%; mHCT116: −31%; quadriceps muscle) and strength (HCT116: −20%; mHCT116: −27%), with worsened loss of SkM mass in mHCT116 compared to HCT116 (gastrocnemius: −19%; tibialis anterior: −22%; quadriceps: −21%). Molecular analyses revealed elevated protein ubiquitination in HCT116, whereas mHCT116 also displayed elevated Murf-1 and Atrogin-1 expression, along with reduced mitochondrial proteins PGC1α, OPA1, Mitofusin-2, and Cytochrome-C. Further, elevated IL-6 levels were found in the blood of mHCT116 hosts, which was associated with higher phosphorylation of STAT3 in SkM. To clarify if STAT3 was a main player in muscle wasting in this model, HCT116 cells were co-cultured with C2C12 myotubes. Marked myotube atrophy (–53%) was observed, along with elevated phospho-STAT3 levels (+149%). Conversely, inhibition of STAT3 signaling by means of a JAK/STAT3 inhibitor was sufficient to rescue myotube atrophy induced by HCT116 cells (+55%). Overall, our results indicate that the formation of LM exacerbates cachectic phenotype and associated SkM molecular alterations in HCT116 tumor hosts.