γ-secretase inhibitor I inhibits neuroblastoma cells, with NOTCH and the proteasome among its targets

// Carmen Dorneburg 1 , Annika V. Gos 1 , Matthias Fischer 2 , Frederik Roels 2 , Thomas F.E. Barth 3 , Frank Berthold 2 , Roland Kappler 4 , Franz Oswald 5 , Jens T. Siveke 6 , Jan J. Molenaar 7 , Klaus-Michael Debatin 1 , and Christian Beltinger 1 1 Department of Pediatrics and Adolescent Medicine, University Medical Center Ulm, Ulm, Germany 2 Children’s Hospital, Department of Pediatric Oncology and Hematology, University of Cologne, Cologne, Germany 3 Department of Pathology, University Medical Center Ulm, Ulm, Germany 4 Department of Pediatric Surgery, Dr. von Hauner Children’s Hospital, Ludwig-Maximilians-University, Munich, Germany 5 Department of Internal Medicine I, University Medical Center Ulm, Ulm, Germany 6 Department of Internal Medicine, University Hospital Essen, Essen, Germany 7 Department of Oncogenomics, Academic Medical Center, Amsterdam, The Netherlands Correspondence to: Christian Beltinger, email: // Keywords : γ-secretase inhibitor, NOTCH, neuroblastoma, preclinical, in vivo Received : March 04, 2016 Accepted : August 12, 2016 Published : August 30, 2016 Abstract As high-risk neuroblastoma (NB) has a poor prognosis, new therapeutic modalities are needed. We therefore investigated the susceptibility of NB cells to γ-secretase inhibitor I (GSI-I). NOTCH signaling activity, the cellular effects of GSI-I and its mechanisms of cytotoxicity were evaluated in NB cells in vitro and in vivo . The results show that NOTCH signaling is relevant for human NB cells. Of the GSIs screened in vitro GSI-I was the most effective inhibitor of NB cells. Both MYCN- amplified and non-amplified NB cells were susceptible to GSI-I. Among the targets of GSI-I in NB cells were NOTCH and the proteasome. GSI-I caused G2/M arrest that was enhanced by acute activation of MYCN and led to mitotic dysfunction. GSI-I also induced proapoptotic NOXA. Survival of mice bearing an MYCN non-amplified orthotopic patient-derived NB xenograft was significantly prolonged by systemic GSI-I, associated with mitotic catastrophe and reduced angiogenesis, and without evidence of intestinal toxicity. In conclusion, the activity of GSI-I on multiple targets in NB cells and the lack of gastrointestinal toxicity in mice are advantageous and merit further investigations of GSI-I in NB.