TY - JOUR A1 - Fischer, Kyra A1 - Tognarelli, Sara A1 - Rösler, Stefanie A1 - Boedicker, Cathinka A1 - Schubert, Ralf A1 - Steinle, Alexander A1 - Klingebiel, Thomas A1 - Bader, Peter A1 - Fulda, Simone A1 - Ullrich, Evelyn T1 - The smac mimetic BV6 improves NK cell-mediated killing of rhabdomyosarcoma cells by simultaneously targeting tumor and effector cells T2 - Frontiers in immunology N2 - Rhabdomyosarcoma (RMS), the most common cancer of connective tissues in pediatrics, is often resistant to conventional therapies. One underlying mechanism of this resistance is the overexpression of Inhibitor of Apoptosis (IAP) proteins, leading to a dysfunctional cell death program within tumor cells. Smac mimetics (SM) are small molecules that can reactivate the cell death program by antagonizing IAP proteins and thereby compensating their overexpression. Here, we report that SM sensitize two RMS cell lines (RD and RH30) toward natural killer (NK) cell-mediated killing on the one hand, and increase the cytotoxic potential of NK cells on the other. The SM-induced sensitization of RH30 cells toward NK cell-mediated killing is significantly reduced through blocking tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) on NK cells prior to coculture. In addition, the presence of zVAD.fmk, a pancaspase inhibitor, rescues tumor cells from the increase in killing, indicating an apoptosis-dependent cell death. On the NK cell side, the presence of SM in addition to IL-2 during the ex vivo expansion leads to an increase in their cytotoxic activity against RH30 cells. This effect is mainly TNFα-dependent and partially mediated by NK cell activation, which is associated with transcriptional upregulation of NF-κB target genes such as IκBα and RelB. Taken together, our findings implicate that SM represent a novel double-hit strategy, sensitizing tumor and activating NK cells with one single drug. KW - natural killer cells KW - second mitochondria-derived activator of caspases mimetic KW - rhabdomyosarcoma KW - RH30 cells KW - RD cells KW - BV6 Y1 - 2017 UR - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/43174 UR - https://nbn-resolving.org/urn:nbn:de:hebis:30:3-431745 UR - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5339542 SN - 1664-3224 N1 - Copyright © 2017 Fischer, Tognarelli, Roesler, Boedicker, Schubert, Steinle, Klingebiel, Bader, Fulda and Ullrich. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms. VL - 8 IS - Art. 202 SP - 1 EP - 11 PB - Frontiers Media CY - Lausanne ER -