Preclinical investigation of the novel histone deacetylase inhibitor AR-42 in the treatment of cancer-induced cachexia

Purpose: We assessed the anti-cachectic activity of the novel HDAC inhibitor AR-42 in murine models of cancer cachexia. Methods: Effects on classic features of cachexia, including decreased body weight, skeletal muscle and adipose tissue mass, muscle fiber cross-sectional area, and muscle strength, and increased intramuscular mRNA expression of E3 ligases Atrogin-1/MAFbx and MuRF1 were examined. Metabolomic analysis, whole transcriptome shotgun sequencing (RNA-seq) analysis, and cytokine profiling were used to compare metabolic phenotype and mRNA expression profiles in muscle, and cytokine production in serum, respectively, in AR-42- and vehicle-treated tumor-bearing and tumor-free control mice. Results: Orally administered AR-42 suppressed cancer cachexia in the C-26 colon adenocarcinoma model. This anti-cachectic effect, also confirmed in Lewis lung carcinoma-bearing mice, was not observed after treatment with other HDAC inhibitors (vorinostat, romidepsin). Cytokine profiling and RNA-seq analyses revealed effects of AR-42 on tumor-induced changes in inflammatory cytokine production and multiple transcriptional programs in muscle, including the inhibition of multiple pro-cachexia drivers, such as IL-6 and its receptor IL-6ra, leukemia inhibitory factor, Foxo1, Atrogin-1, MuRF1, adipose triglyceride lipase, uncoupling protein 3, and myocyte enhancer factor 2c. Metabolomic analysis indicated the reprogramming of skeletal muscle metabolism, including reduced glycolysis and glycogen synthesis and increased protein degradation, which was restored by AR-42 to a state characteristic of tumor-free mice. Conclusions: These findings support further investigation of AR-42 as part of a comprehensive therapeutic strategy for cancer cachexia. Overall design: Mice bearing subcutaneous C-26 tumors, as well as tumor-free mice, were randomized into groups that were treated with either AR-42 (50 mg/kg, p.o. by gavage, every other day) or vehicle (0.5% methylcellulose (w/v) and 0.1% Tween-80 (v/v) in sterile water) starting 6 days after cell injection. Skeletal muscles (hind limb) were harvested at terminal sacrifice on day-15 after tumor cell injection, snap-frozen in liquid nitrogen, and stored at -80 degress F until analysis. For RNA-seq, 3 muscle samples were analyzed from each of 4 groups: (a) tumor-bearing/vehicle treated (T/Veh); (b) tumor-bearing/AR-42-treated (T/AR); (c) tumor-free/vehicle-treated (TF/Veh); (d) tumor-free/Ar-42-treated (TF/AR).