Abstract 3195: Synergistic effects of combined treatment with hAT-MSC.sTRAIL and panobinostat in brainstem glioma

Abstract

Abstract Human adipose-derived mesenchymal stem cells expressing secreted form of the tumor necrosis factor-related apoptosis-inducing ligand (hAT-MSC.sTRAIL) have demonstrated therapeutic activity against various tumors. However, sTRAIL resistance remains a challenge in developing anticancer strategies. To solve this problem, many studies have tried to combine drugs to produce synergism or sensitize resistant cancer cells. Histone deacetylase inhibitors (HDACi) have been known to induce expression of TRAIL death receptors 4 and 5 (DR4/DR5). Herein, we evaluated the use of combined therapy of hAT-MSC.sTRAIL with HDAC inhibitor, panobinostat, in enhancing sensitivity to hAT-MSC.sTRAIL mediated apoptosis against the brainstem glioma. A sTRAIL was introduced into the characterized hAT-MSCs using electroporation. To confirm appropriate treatment concentration of panobinostat to the glioblastoma cells, dose titration was tested using cell viability assay. The therapeutic effect of single or combination treatment against glioblastoma was evaluated using primary cultured glioblastoma cells and cell lines. Orthotopic xenograft brainstem glioma mouse model was established using engineered firefly luciferase expressing tumor cells for bioluminescence in vivo imaging. Panobinostat induced anti-proliferative effects in dose and time-dependent manner (IC50 range, 0.05-0.2 μM) and effectively enhanced the expression of TRAIL DR4 and DR5, but not decoy receptors. Combined hAT-MSC.sTRAIL and panobinostat significantly decreased the tumor cell growth compared to each alone. Intriguingly, the combination treatment not only induced apoptosis but also autophagy. Using a preclinical brainstem mouse model, we confirmed that the combination of hAT-MSC.sTRAIL and panobinostat was safe and induced regression of tumor volume. Furthermore, the combination therapy prolonged the survival of brainstem glioma-bearing mice. Our results suggested that combination therapy of panobinostat enhanced the anti-cancer effect of hAT-MSC.sTRAIL and represent potential therapeutic approach to the brainstem glioma. Citation Format: Seung Ah Choi, Chanhee Lee, Pil Ae Kwak, Kyu-Chang Wang, Ji Hoon Phi, Ji Yeoun Lee, Sangjoon Chong, Seung-Ki Kim. Synergistic effects of combined treatment with hAT-MSC.sTRAIL and panobinostat in brainstem glioma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3195.