Conclusions
MPNST is an aggressive sarcoma that is notoriously therapy-resistant, hence the urgent need for improved anti-MPNST therapies. HDAC8 inhibition may be useful for MPNST by improving efficacy while limiting toxicities as compared to pan-HDACis.
Methods
Four Human MPNST cell lines, a murine-derived MPNST cell line, and two HDAC8 inhibitors (PCI-34051, PCI-48012; Pharmacyclics, Inc. Sunnyvale, CA) were studied. Proliferation was determined using MTS and clonogenic assays. Effects on cell cycle were determined via PI FACS analysis; effects on apoptosis were determined using Annexin V-PI FACS analysis and cleaved caspase 3 expression. In vivo growth effects of HDAC8i were evaluated using MPNST xenograft models. 2D gel electrophoresis and mass spectrometry were used to identify potential HDAC8 deacetylation substrates.
Results
HDAC8i induced cell growth inhibition and marked S-phase cell cycle arrest in human and murine-derived MPNST cells. Relative to control, HDAC8i induced apoptosis in both human and murine-derived MPNST cells. HDAC8i exhibited significant effects on MPNST xenograft growth (p=0.001) and tumor weight (p=0.02). Four potential HDAC8 substrate targets were identified using a proteomic approach: PARK7, HMGB1, PGAM1, PRDX6. Conclusions: MPNST is an aggressive sarcoma that is notoriously therapy-resistant, hence the urgent need for improved anti-MPNST therapies. HDAC8 inhibition may be useful for MPNST by improving efficacy while limiting toxicities as compared to pan-HDACis.