Dual Targeting EZH2 and Histone Deacetylases in Human Uterine Sarcoma Cells Under Both 2D and 3D Culture Conditions.

Uterine sarcoma is strongly associated with poor prognosis. However, its treatment options remain limited. Tazemetostat is a potent and selective EZH2 inhibitor with limited clinical application. Entinostat is one of the strong inhibitors for HDAC1 and HDAC3. This study aimed to assess the effect of dual targeting of EZH2 and HDACs on the phenotype of uterine sarcoma cells in both 2D and 3D culture systems. The uterine sarcoma cell line (MES-SA) was treated with varying concentrations of tazemetostat and/or entinostat for 24, 48 and 72 h. For 3D culture conditions, the cells were combined with Matrigel and seeded in V-bottom plates and incubated for 5 days. Cell proliferation, cell cycle progression and apoptosis were evaluated. Additionally, the RNA expression, IHC staining, wound healing assay, DNMT and HDAC activity measurements were conducted. Our data showed that single-inhibitor treatment with entinostat or tazemetostat significantly increased the cytotoxicity and significantly enhanced apoptosis concomitantly. Furthermore, both inhibitors induced cell cycle arrest in 2D and 3D culture conditions. We also demonstrated that entinostat, but not tazemetostat, suppressed the wound healing in the 2D culture. The combination treatment showed a significantly superior effect compared to single-agent treatment. Our studies demonstrate that treatment with either entinostat or tazemetostat alone showed a potent anti-uterine sarcoma effect in 2D and 3D culture conditions. Importantly, the combination of entinostat and tazemetostat produced superior therapeutic effects, suggesting that dual targeting EZH2 and HDACs may provide a promising treatment option for this aggressive cancer.