Research Project: Identification of TRAIL sensivity/resistance mechanisms and searching for novel TRAIL-sensitizing agents in Glioblastoma Multiforme
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Contributors
Funders
ID
EC.00058
Authors
Önder, Tuğba Bağcı
Faculty Member
Publications
The pro-apoptotic Bcl-2 family member Harakiri (HRK) induces cell death in glioblastoma multiforme
(Nature Publishing Group (NPG), 2019) Cingöz, Ahmet; Karahüseyinoğlu, Serçin; Kayabölen, Alişan; Kaya, Ezgi; Lokumcu, Tolga; Önder, Tuğba Bağcı; Şahin, Gizem Nur; Şeker-Polat, Fidan; Şenbabaoğlu, Filiz; Sur, İlknur Erdem; School of Medicine; Yes; SCHOOL OF MEDICINE
Harakiri (HRK) is a BH3-only protein of the Bcl-2 family and regulates apoptosis by interfering with anti-apoptotic Bcl-2 and Bcl-xL proteins. While its function is mainly characterized in the nervous system, its role in tumors is ill-defined with few studies demonstrating HRK silencing in tumors. In this study, we investigated the role of HRK in the most aggressive primary brain tumor, glioblastoma multiforme (GBM). We showed that HRK is differentially expressed among established GBM cell lines and that HRK overexpression can induce apoptosis in GBM cells at different levels. This phenotype can be blocked by forced expression of Bcl-2 and Bcl-xL, suggesting the functional interaction of Bcl-2/ Bcl-xL and HRK in tumor cells. Moreover, HRK overexpression cooperates with tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), a known tumor-specific pro-apoptotic agent. Besides, secondary agents that augment TRAIL response, such as the histone deacetylase inhibitor MS-275, significantly increases HRK expression. In addition, GBM cell response to TRAIL and MS-275 can be partly abolished by HRK silencing. Finally, we showed that HRK induction suppresses tumor growth in orthotopic GBM models in vivo, leading to increased survival. Taken together, our results suggest that HRK expression is associated with GBM cell apoptosis and increasing HRK activity in GBM tumors might offer new therapeutic approaches.
Kdm2b, an h3k36-specific demethylase, regulates apoptotic response of gbm cells to trail
(Nature Publishing Group (NPG), 2017) Cingöz, Ahmet; Kahya, Zeynep; Karahüseyinoğlu, Serçin; Kaya, Ezgi; Kaya, Zeynep; Kazancıoğlu, Selena; Kurt, İbrahim Çağrı; Lack, Nathan Alan; Önder, Tamer Tevfik; Önder, Tuğba Bağcı; Özyerli, Ezgi; Şenbabaoğlu, Filiz; Sur, İlknur Erdem; Toparlak, Ömer Duhan; Gumus, Zeynep H.; School of Medicine; Graduate School of Health Sciences; Yes; GRADUATE SCHOOL OF HEALTH SCIENCES; SCHOOL OF MEDICINE
Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) can selectively kill tumor cells. TRAIL resistance in cancers is associated with aberrant expression of the key components of the apoptotic program. However, how these components are regulated at the epigenetic level is not understood. In this study, we investigated novel epigenetic mechanisms regulating TRAIL response in glioblastoma multiforme (GBM) cells by a short-hairpin RNA loss-of-function screen. We interrogated 48 genes in DNA and histone modification pathways and identified KDM2B, an H3K36-specific demethylase, as a novel regulator of TRAIL response. Accordingly, silencing of KDM2B significantly enhanced TRAIL sensitivity, the activation of caspase-8, -3 and -7 and PARP cleavage. KDM2B knockdown also accelerated the apoptosis, as revealed by live-cell imaging experiments. To decipher the downstream molecular pathways regulated by KDM2B, levels of apoptosis-related genes were examined by RNA-sequencing upon KDM2B loss, which revealed derepression of proapoptotic genes Harakiri (HRK), caspase-7 and death receptor 4 (DR4) and repression of antiapoptotic genes. The apoptosis phenotype was partly dependent on HRK upregulation, as HRK knockdown significantly abrogated the sensitization. KDM2B-silenced tumors exhibited slower growth in vivo. Taken together, our findings suggest a novel mechanism, where the key apoptosis components are under epigenetic control of KDM2B in GBM cells.
The fungal metabolite chaetocin is a sensitizer for pro-apoptotic therapies in glioblastoma
(Nature Publishing Group (NPG), 2019) Cingöz, Ahmet; Gönen, Mehmet; Kahya, Zeynep; Kayabölen, Alişan; Önder, Tuğba Bağcı; Özyerli, Ezgi; Şeker-Polat, Fidan; Sur, İlknur Erdem; Uyulur, Fırat; Gezen, Melike; Tolay, Nazife; Erman, Batu; Dunford, James; Oppermann, Udo; Department of Molecular Biology and Genetics; Department of Industrial Engineering; Graduate School of Health Sciences; Graduate School of Sciences and Engineering; School of Medicine; Yes; College of Engineering; College of Sciences; GRADUATE SCHOOL OF HEALTH SCIENCES; GRADUATE SCHOOL OF SCIENCES AND ENGINEERING; SCHOOL OF MEDICINE
Glioblastoma Multiforme (GBM) is the most common and aggressive primary brain tumor. Despite recent developments in surgery, chemo- and radio-therapy, a currently poor prognosis of GBM patients highlights an urgent need for novel treatment strategies. TRAIL (TNF Related Apoptosis Inducing Ligand) is a potent anti-cancer agent that can induce apoptosis selectively in cancer cells. GBM cells frequently develop resistance to TRAIL which renders clinical application of TRAIL therapeutics inefficient. In this study, we undertook a chemical screening approach using a library of epigenetic modifier drugs to identify compounds that could augment TRAIL response. We identified the fungal metabolite chaetocin, an inhibitor of histone methyl transferase SUV39H1, as a novel TRAIL sensitizer. Combining low subtoxic doses of chaetocin and TRAIL resulted in very potent and rapid apoptosis of GBM cells. Chaetocin also effectively sensitized GBM cells to further pro-apoptotic agents, such as FasL and BH3 mimetics. Chaetocin mediated apoptosis sensitization was achieved through ROS generation and consequent DNA damage induction that involved P53 activity. Chaetocin induced transcriptomic changes showed induction of antioxidant defense mechanisms and DNA damage response pathways. Heme Oxygenase 1 (HMOX1) was among the top upregulated genes, whose induction was ROS-dependent and HMOX1 depletion enhanced chaetocin mediated TRAIL sensitization. Finally, chaetocin and TRAIL combination treatment revealed efficacy in vivo. Taken together, our results provide a novel role for chaetocin as an apoptosis priming agent and its combination with pro-apoptotic therapies might offer new therapeutic approaches for GBMs.
Generation of TRAIL-resistant cell line models reveals distinct adaptive mechanisms for acquired resistance and re-sensitization
(Springer Nature, 2021) Cingöz, Ahmet; Gümüş, Zeynep Hülya; Morova, Tunç; Önder, Tuğba Bağcı; Özyerli, Ezgi; Şeker-Polat, Fidan; Solaroğlu, İhsan; Esai Selvan, Myvizhi; Bhere, Deepak; Shah, Khalid; School of Medicine; KUTTAM (Koç University Research Center for Translational Medicine); Yes; SCHOOL OF MEDICINE; Research Center
Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) induces tumor cell-specific apoptosis, making it a prime therapeutic candidate. However, many tumor cells are either innately TRAIL-resistant, or they acquire resistance with adaptive mechanisms that remain poorly understood. In this study, we generated acquired TRAIL resistance models using multiple glioblastoma (GBM) cell lines to assess the molecular alterations in the TRAIL-resistant state. We selected TRAIL-resistant cells through chronic and long-term TRAIL exposure and noted that they showed persistent resistance both in vitro and in vivo. Among known TRAIL-sensitizers, proteosome inhibitor Bortezomib, but not HDAC inhibitor MS-275, was effective in overcoming resistance in all cell models. This was partly achieved through upregulating death receptors and pro-apoptotic proteins, and downregulating major anti-apoptotic members, Bcl-2 and Bcl-xL. We showed that CRISPR/Cas9 mediated silencing of DR5 could block Bortezomib-mediated re-sensitization, demonstrating its critical role. While overexpression of Bcl-2 or Bcl-xL was sufficient to confer resistance to TRAIL-sensitive cells, it failed to override Bortezomib-mediated re-sensitization. With RNA sequencing in multiple paired TRAIL-sensitive and TRAIL-resistant cells, we identified major alterations in inflammatory signaling, particularly in the NF-kappa B pathway. Inhibiting NF-kappa B substantially sensitized the most resistant cells to TRAIL, however, the sensitization effect was not as great as what was observed with Bortezomib. Together, our findings provide new models of acquired TRAIL resistance, which will provide essential tools to gain further insight into the heterogeneous therapy responses within GBM tumors. Additionally, these findings emphasize the critical importance of combining proteasome inhibitors and pro-apoptotic ligands to overcome acquired resistance.
