Synergistic anticancer effect of a combination of chidamide and etoposide against NK/T cell lymphoma.

Natural killer/T cell lymphoma (NKTCL) is a highly aggressive hematological malignancy. However, there is currently no consensus on therapies for refractory/relapsed patients. In this study, we investigated the synergistic anticancer effect and potential mechanism of combining chidamide, a histone deacetylases (HDACs) inhibitor, and etoposide, a DNA-damaging agent, in NKTCL. We demonstrated that chidamide or etoposide alone dose- and time-dependently inhibited the cell viability of NKTCL cell lines, YT, NKYS and KHYG-1. Functional experiments suggested that combined chidamide and etoposide treatment exerted synergistic antiproliferation effect and enhanced cell apoptotic death in vitro and in vivo. Furthermore, the expression of DNA damage related proteins was detected and we also examined the alternations in histone acetylation, cell cycle progression, and mitochondrial membrane potential (MMP). The results suggested that increased histone acetylation, cell cycle arrest at the G2/M phase and loss of MMP, converging to greater DNA damage, might account for the synergism of the combination of chidamide and etoposide in NKTCL. Taken together, our study provides an evident for possible application on combining HDACs inhibitors and DNA-damaging agents for the treatment of NKTCL.