Presented in the order of the program. Not all speakers submitted abstracts: This page is not available from the website home page. Late speaker abstracts can be accepted during the meeting.
Monday JUNE 7th – 9:00AM-11:30 AM
SESSION 1: Cell death new ideas in therapeutics
Introduction: Zahra Zakeri, Queens College of CUNY, USA
Chair: Richard A Lockshin, St. John’s Univ., USA
Patrizia Agostinis, Univ. Leuven, Belgium., “Autophagy, a key player of the tumor-stroma dialogue and responses to inflammation”
Peter Vandenabeele, Univ. Ghent, Belgium., “Interaction of ferroptotic cancer cells and the immune system during prophylactic anti-cancer vaccination”
Short Talk – Ozlem Yedier-Bayram, Koç University, Turkey, “Unravelling epigenetic modifiers that regulate therapy resistance in triple negative breast cancer through epigenome-wide knockout screens”
Ozlem YEDIER-BAYRAM1,2, Ali Cenk AKSU1,2, Ayşe Derya Cavga1,2, Alisan
KAYABOLEN1,2, Ezgi Yagmur KALA1,2, Goktug KARABIYIK1,2, Tunc MOROVA1, Firat
UYULUR1,, Nathan LACK1,2,, Tamer T. ÖNDER1,2,, Tugba BAGCI-ONDER 1,2,*
1Koç University School of Medicine, Istanbul, Turkey
2Koç University Research Center for Translational Medicine, Istanbul, Turkey
Triple negative breast cancer (TNBC) is an aggressive subtype of breast cancer with poor prognosis. TNBC tumors do not express receptors for estrogen, progesterone or Her2, eliminating the possibility of targeted therapy applications. Therefore, current treatment option for TNBC is limited with surgery followed by conventional chemotherapy. However, acquired resistance to chemotherapy is a major challenge that in part causes in relapse, which is thought to be driven by coordinated actions of genetic and epigenetic events. Here, we aimed to elucidate the roles of full spectrum of epigenetic modifiers in induction and maintenance of chemoresistance in TNBC. We designed a CRISPR-Cas9 library targeting all chromatin readers, writers, erasers and associated proteins (Epigenetic Knock-Out Library – EPIKOL) to systematically interrogate the roles of epigenetic modifiers in naïve and chemoresistant TNBC cells. EPIKOL targets 779 genes with 10 sgRNAs per gene, including multiple controls and 35 essential genes to serve as depletion controls. First, through pooled EPIKOL screens on TNBC cell lines, we identified novel epigenetic modifiers crucial for cancer cell fitness. Members of the NSL complex were commonly depleted in all TNBC cell lines except the non-malignant control cell line, HMLE. We validated that the suppression of members of the NSL complex (KAT8, KANSL2 and KANSL3) caused cell fitness defects and increased apoptosis. Second, we generated chemoresistant TNBC models by exposing 3 different cell lines to escalating doses of Paclitaxel. Transcriptome analysis by RNA-sequencing were performed to reveal epigenetic modifiers that regulate chemoresistance. Next, we performed EPIKOL screen on paclitaxel-resistant cell lines and identified novel epigenetic regulators of chemotherapy resistance. Inhibition of the members of MLL and SWI/SNF complexes, as well as the genes related with histone ubiquitination re-sensitized chemoresistant cells. In summary, through EPIKOL screens on naïve and chemoresistant TNBC cells, we identified novel epigenetic modifiers that are crucial for cancer cell fitness and drug resistance. Collectively, these findings provide a basis to develop combination therapies targeting specific chromatin-based epigenetic factors to counteract TNBC cell viability and chemoresistant phenotype.
Key words: Epigenetics, CRISPR/Cas9, breast cancer, drug resistance, fitness
This work was supported by The Scientific and Technological Research Council of Turkey
(TUBITAK) 1003- 216S461 Grant
Short Talk – Marietta Zille, Burke Neurological Institute, Weill Cornell Medicine, and University of Lübeck, USA and Germany, “Hemin-induced death models hemorrhagic stroke and is a variant of classical neuronal ferroptosis:
Marietta Zille1,2,3, Saravanan S. Karuppagounder1,2, Yingxin Chen1,2, Amit Kumar1,2, Juan A. Oses-Prieto4, Alma L. Burlingame4, John H. Morris5, Rajiv R. Ratan1,2
1Burke Neurological Institute, 785 Mamaroneck Avenue, White Plains, NY 10605, USA 2Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, 407 E 61st Street, New York, NY 10065, USA
3Institute for Experimental and Clinical Pharmacology and Toxicology, University of Lübeck, Ratzeburger Allee 160, 23562 Lübeck, Germany
4Department of Pharmaceutical Chemistry, University of California, 600 16th Street, San Francisco, CA 94158, USA
5Resource on Biocomputing, Visualization, and Informatics, University of California, 600 16th Street, San Francisco, CA 94158, USA
Ferroptosis is a caspase-independent, iron-dependent form of regulated necrosis extant in rodent models of traumatic brain injury, Huntington’s disease, and hemorrhagic stroke. It can be activated by cystine deprivation leading to glutathione depletion, the insufficiency of the antioxidant glutathione peroxidase-4, and the hemolysis products hemoglobin and hemin. A cardinal feature of ferroptosis is the activation of extracellular regulated kinase (ERK) 1/2 culminating in its translocation to the nucleus. We have previously confirmed that the mitogen activated protein kinase kinase (MEK) inhibitor U0126 inhibits persistent ERK1/2 phosphorylation and ferroptosis. Here, we show that hemin exposure, a model of secondary injury in brain hemorrhage and ferroptosis, activated ERK1/2 in neurons. Accordingly, the MEK inhibitor U0126 protected against hemin-induced ferroptosis. Unexpectedly, U0126 prevented hemin-induced ferroptosis independent of its ability to inhibit ERK1/2 signaling. In contrast to classical ferroptosis in neurons or cancer cells, chemically diverse inhibitors of MEK did not block hemin-induced ferroptosis, nor did the forced expression of the ERK-selective MAP kinase phosphatase (MKP) 3. We conclude that hemin or hemoglobin-induced ferroptosis, unlike that induced by cystine deprivation-induced glutathione depletion, is ERK1/2-independent. Taken together with recent studies, our findings suggest the existence of a novel subtype of neuronal ferroptosis relevant to bleeding in the brain that is 5-lipoxygenase-dependent, and ERK- and transcription-independent. As U0126 also reduced cell death and improved functional recovery after hemorrhagic stroke, our unbiased phosphoproteome analysis of distinct ferroptotic deaths provides a template on which to build a search for U0126’s effects in a variant of neuronal ferroptosis.
SESSION 2: Cell death and Covid-19
Chair: Zahra Zakeri, Queens College of CUNY, USA
Dror Mevorach, Hadassah – Hebrew University, Medical Center in Jerusalem. Israel., “Covid-19 therapeutics strategies: Regulating the uncontrolled immune response”
Covid-19 therapeutics strategies: Regulating the uncontrolled immune response.
Dror Mevorach*, MD
Hadassah-Hebrew University, Jerusalem, Israel.
*Disclosure: DM is the CSO of Enlivex Therapeutics
The newly emerging coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was first reported in Wuhan, China, but has rapidly spread all over the world. Some COVID-19 patients encounter a severe symptom of acute respiratory distress syndrome (ARDS)-like disease with high mortality. This high severity is dependent on a cytokine storm, not most completely understood but involves nuclear factor kappa B (NF-κB) pathway and signalling in immune cells and non-immune cells. As a result, dozens of cytokines and chemokines are increased and both alveolar epithelial cells and endothelial cells are activated.
The pro-homeostatic nature of apoptotic cell clearance and interaction with the immune system leading to well characterized signalling events in macrophages and dendritic cells and are related to toll-like receptors, NF-κB, inflammasome, the lipid activated nuclear receptors, Tyro3, Axl, and Mertk receptors, as well as induction of signal transducer and activator of transcription 1(STAT1) and suppressor of cytokine signalling (SOCS), lead to immune system modulation. These properties of apoptotic cells were used to prepare early apoptotic cells (Allocetra) derived from mononuclear cells to treat 21 patients with severe (11) or critical (10) condition. The results being a 19/21 patients being discharged within one week with a complete resolution of cytokine storm measured by inflammation markers and 30 cytokines/chemokines/ hematopoietic growth factors.
The potential pro-homeostatic properties of apoptotic cells in inflammatory conditions will be discussed.
Adolfo García-Sastre, Mt. Sinai School of Medicine, USA, “Covid-19 antiviral discovery”
Development of novel antivirals against SARS-CoV-2
Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
The COVID-19 pandemic caused by SARS-CoV-2 has triggered an unprecedented speed of research towards the development of new therapies and vaccines. I will discuss our approaches and advances for the rational discovery of novel antivirals against SARS-CoV-2.
Tuesday JUNE 8th – 9:00AM-11:30 AM
SESSION 3: Mitochondrial Control of Regulated Cell Death
Chair: Jerry Chipuk, Mt. Sinai School of Medicine, USA
Hülya Bayir M.D.; Univ. Pittsburgh, USA., “Mitochondrial Oxidized Phospholipid Signaling in Regulated Cell Death”
Pere Puigserver Ph.D.; Dana-Farber Cancer Inst., USA., “Mechanisms of Mitochondrial Bioenergetic Failures and Cell Death”
Short Talk – Ben Loos, Stellenbosch University, South Africa, “Mitochondrial event localiser (MEL) – a novel tool to quantitatively describe mitochondrial fission, fusion and depolarization”.
Mitochondrial fission and fusion play an important role not only in maintaining mitochondrial homeostasis but also in preserving overall cellular viability. However, quantitative analysis based on the three-dimensional localisation of these highly dynamic mitochondrial events in the cellular context has not yet been accomplished. Moreover, it remains largely uncertain where in the mitochondrial network depolarisation is most likely to occur. Here, we present the mitochondrial event localiser (MEL), a method that allows high-throughput, automated and deterministic localisation and quantification of mitochondrial fission, fusion and depolarisation events in large three-dimensional fluorescence-based microscopy time-lapse sequences. In addition, MEL calculates the number of mitochondrial structures as well as their combined and average volume for each image frame in the time-lapse sequence. The mitochondrial event locations can subsequently be visualised by superposition over the fluorescence micrograph z-stack. We conclude that MEL is a viable method of quantitative mitochondrial event analysis, particularly for model systems associated with the study of cell death and mitochondrial quality control.
Short Talk — Inna Rabinovich-Nikitin, St. Boniface Hospital Albrechtsen Research Centre, Canada, “Mitochondrial autophagy and cell survival is regulated by the circadian clock gene in cardiac myocytes during ischemic stress”
Inna Rabinovich-Nikitin‡, Victoria Margulets‡, Rimpy Dhingra‡, and Lorrie A. Kirshenbaum‡†¶ ζ
Department of Physiology and Pathophysiology, The Institute of Cardiovascular Sciences, St. Boniface Hospital Albrechtsen Research Centre, Winnipeg, Manitoba, Canada,
Cardiac function is highly reliant on mitochondrial oxidative metabolism and quality control. The circadian Clock gene is critically linked to vital physiological processes including mitochondrial fission, fusion and bioenergetics, however, little is known of how the Clock gene regulates these vital processes in the heart. Herein, we identified a putative circadian CLOCK-mitochondrial interactome that gates an adaptive survival response during myocardial ischemia. We show by transcriptome and gene ontology mapping in CLOCK 19/19 mouse, that Clock transcriptionally coordinates the efficient removal of damaged mitochondria during myocardial ischemia by directly controlling transcription of genes required for mitochondrial fission, fusion and macroautophagy/autophagy. Loss of Clock gene activity impaired mitochondrial turnover resulting in the accumulation of damaged reactive oxygen species (ROS) producing mitochondria from impaired mitophagy. This coincided with ultrastructural defects to mitochondria, and impaired cardiac function. Interestingly, wild type CLOCK but not mutations of CLOCK defective for E-Box binding or interaction with its cognate partner ARNTL/BMAL-1 suppressed mitochondrial damage and cell death during acute hypoxia. Interestingly, the autophagy defect and accumulation of damaged mitochondria in CLOCK-deficient cardiac myocytes, was abrogated by restoring autophagy/mitophagy. Inhibition of autophagy by ATG7 knockdown abrogated the cytoprotective effects of CLOCK. Collectively, our results demonstrate that CLOCK regulates an adaptive stress response critical for cell survival by transcriptionally coordinating mitochondrial quality control mechanisms in cardiac myocytes. Interdictions that restore CLOCK activity may prove beneficial in reducing cardiac injury in individuals with disrupted circadian CLOCK.
Anne Hamacher-Brady, Ph.D.; Johns Hopkins Univ., USA., “Endolysosomes as Determinants of Mitochondrial Cell Death Signaling”
Luca Scorrano, M.D. Ph.D., Univ. Padua, Italy., “Keeping Mitochondria in Shape: A Matter of Life and Death”
Wednesday JUNE 9th – 9:00AM-11:30 AM
SESSION 4: “Caspases in Cancer; expected and surprising outcomes”
Chair: Sarit Larisch, Univ. Haifa, Israel
Philippe Jost, Medical Univ. Graz, Austria and Technical Univ. Munich, Germany., “Cell death and inflammation in myeloid leukemia”
Eli Arama, Weizmann Institute, Israel., “Inhibition of EMT and cell invasion by sub-lethal levels of caspase activity in Drosophila.”
Short Talk – K. Berthenet, CRCL and Université de Lyon, France, “Failed apoptosis enhances melanoma cancer aggressiveness”
Berthenet, K1, 2., Castillo Ferrer1, C.1, Popgeorgiev1, N., Hernandez-Vargas1, H., Ichim, G.1, 2 *
1 INSERM 1052, CNRS 5286, Cancer Research Center of Lyon (CRCL), Lyon, France.
2 LabEx DEVweCAN, Université de Lyon, Lyon, France
* Corresponding author: Gabriel.email@example.com
Apoptosis is without a doubt the spearhead of many anti-cancer chemotherapeutic drugs and radiotherapy. It is commonly accepted that the point of no return in the apoptotic process is the mitochondrial outer-membrane permeabilization (MOMP), followed by cytochrome c release, apoptosome assembly and massive caspase activation. Widespread effector caspase activation following complete MOMP kills a cell within minutes by cleaving hundreds of vital protein substrates. However, recent research has consistently shown caspases could be activated without inducing cell death. Moreover, non-lethal caspase activation has vital roles such as macrophages differentiation, muscle and neuronal function and even stemness or induced pluripotent stem cells. In cancer, failed apoptosis could have a dark side by damaging the DNA, triggering genomic instability and favoring oncogenic transformation. The generalizability of much research published on this issue is problematic in properly addressing a key question: what are the phenotypic consequences of failed apoptosis on cancer cells. This is particularly important since cancer drugs do not kill all cancer cells and the surviving ones are responsible for cancer relapse, drug resistance, metastasis and increased mortality.
This study therefore set out to assess the phenotypic effects of failed apoptosis. For this, we focused on melanoma since it is one of the most aggressive cancers, having a high rate of mortality. Using a sensitive caspase activation reporter in settings of failed apoptosis (inefficient BH3-only protein activation and non-lethal doses of chemotherapy), we isolated and thoroughly characterized melanoma cancer cells surviving the induction of apoptosis. Importantly, our results suggest these cells have a particular transcriptomic signature associated with focal adhesions, trans-endothelial migration and modifications of actin cytoskeleton. In line with this, cells surviving apoptosis have a gain in aggressiveness: they have an increased migration and invasion potential both in vitro (random migration, chemotaxis, wound healing and invasion assays) and in vivo (in models of Zebrafish and mouse metastasis) that is governed by the JNK-AP1 transcriptional axis.
Short Talk – Dana Mamriev, University of Haifa, Israel, “ARTS mimetic small-molecules promote the reversion of pre-malignant breast cells to a normal-like phenotype”
Dana Mamriev1, 2, Fatimah Hijaze1, 2, Keren Weidenfeld2, Dalit Barkan2 and Sarit Larisch1
1 Cell Death and Cancer Research Laboratory, Department of Biology, University of Haifa, Haifa 31905, Israel.
2 Tumor Dormancy and Metastasis Research Laboratory, Department of Biology, University of Haifa, Haifa 31905, Israel.
Breast cancer is one of the most common cancers and a major cause of death among women worldwide. We have investigated the role of the pro-apoptotic and tumor suppressor protein, ARTS, in tumorigenesis and progression of breast cancer. For that purpose we have used the MCF10 breast cancer 3D organoid model system which consist of normal (M1), pre-malignant (M2) and malignant ductal breast cells (M3). Interestingly ARTS was aberrantly expressed in pre-malignant M2 cells and these cells have showed reduce response to apoptotic stimuli. Preliminary results showed that exogenous expression of wild type ARTS in M2 cells resulted in reversion of the pre-malignant phenotype to a normal-like phenotype. Furthermore treatment of pre-malignant M2 cells with ARTS-mimetic small molecules similarly resulted in reversion of M2 cells into normal-like phenotype, with defined apico-basal polarization depicted by GM-130 and Laminin-5 respectively. We found moderate activation of caspase-3 in ARTS-mimetic small molecules treated M2 cells, with no apparent apoptosis. This is consistent with known effects of low levels active caspase 3 on promoting differentiation in various tissues.
Remarkably, knockdown of ARTS in M1 organoids, resulted in loss of apico-basal polarization resembling the M3 malignant phenotype. Together, these results suggest that the pro-apoptotic ARTS protein, plays a critical role in the transformation of normal breast tissue. Moreover, that ARTS-mimetic small molecules provide a promising basis for drug development for prevention of breast cancer.
Andreas Bergmann, Univ. Massachusetts Medical School, USA., “Caspase Function in Apoptosis-induced Proliferation”
University of Massachusetts Medical School,
Department of Molecular, Cell and Cancer Biology,
Worcester, MA 06105
Apoptosis and its molecular mediators, the caspases, have long been regarded as tumor suppressors and one hallmark of cancer is “Evading Apoptosis”. However, more recent evidence has suggested that apoptotic caspases can also promote proliferation and tumor growth under certain conditions. For example, apoptotic caspases, most notably the initiator caspase Dronc (Caspase-9 ortholog in Drosophila), can induce apoptosis-induced proliferation (AiP), a process during which caspases release mitogenic signals for compensatory proliferation independently of their apoptotic role. Using the “undead” AiP model, in which we uncouple the AiP function of Dronc from apoptosis by expression of P35, we showed that Dronc stimulates the NADPH oxidase Duox at the plasma membrane for generation of extracellular reactive oxygen species (ROS) which attract and activate Drosophila immune cells (hemocytes) to epithelial cells for AiP. Furthermore, in a genetic screen, we identified mutations of the unconventional myosin, Myo1D, as strong suppressors of AiP. We found that Myo1D, an Actin-based molecular motor, translocates Dronc to the basal side of the plasma membrane where Dronc – directly or indirectly – promotes the activation of Duox for ROS generation and AiP in a non-apoptotic manner. We propose that the basal side of the plasma membrane constitutes a non-apoptotic compartment for caspases.
In a search for a physiological P35-independent AiP model, we started examining the cellular turnover in the Drosophila intestine. The adult intestine turns over every 4 to 8 days due to the mitotic activity of intestinal stem cells (ISCs). Asymmetric ISC division generates a new ISC and an enteroblast which differentiates into an absorptive enterocyte. We found that many of the mechanistic requirements of AiP defined in undead tissue are also used for enterocyte turnover in the adult intestine. Importantly, we observed that in old enterocytes Dronc is localized at the basal site of the plasma membrane in a Myo1D-dependent manner very similar to undead cells in imaginal discs (although these enterocytes are not kept undead by expression of P35). We propose that these enterocytes enter into a transiently “undead”-like state during which they generate the signals including ROS to stimulate ISC activity. A transient “undead”-like state gives old enterocytes time to produce the signals for their replacement before they are dying and localizing Dronc to the membrane protects them from premature apoptosis. These findings will be discussed at the conference.
Dagmar Kulms, University of Dresden, Germany., “Nuclear Caspase-8 promotes progression of p53-proficient tumors.”
Ines Müller1, Elwira Strozyk1, Sebastian Schindler1, Stefan Beissert1, Htoo Zarni Oo3,4, Thomas Sauter5, Philippe Lucarelli5, Sebastian Raeth6, Angelika Hausser6, Nader Al Nakouzi3,4, Ladan Fazli3,4, Martin Gleave3,4, He Liu7, Hans-Uwe Simon7, Henning Walczak8, Douglas R. Green9, Mads Daugaard3,4, Dagmar Kulms1
1Experimental Dermatology, Department of Dermatology, TU-Dresden, 01307 Dresden, Germany
3Department of Urologic Sciences, Vancouver Prostate Centre, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada V5Z 1M9
4Vancouver Prostate Centre, Vancouver, BC, Canada V6H 3Z6
5Systems Biology, Life Science Research Unit, University of Luxembourg, 1511 Luxembourg
6Institute of Cell Biology and Immunology and Stuttgart Research Centre Systems Biology, University of Stuttgart, 70569 Stuttgart, Germany
7Institute of Pharmacology, University of Bern, 3010 Bern, Switzerland
8Centre for Cell Death, Cancer and Inflammation, UCL Cancer Institute, University College London, London WC1E 6DD, UK
9Department of Immunology, St. Judes Children´s Research Hospital, Memphis, TN 38105, USA
Cytosolic caspase-8 is a well-known mediator of death receptor signaling and its suppression can drive necroptosis. While caspase-8 expression is lost in some tumors, it is sustained or increased in others, indicating a conditional pro-survival function of caspase-8 in cancer. Nuclear localization of caspase-8 has been sporadically reported in some cancers, however, the significance of this remains to be elucidated. Here we show that tumor cells harness caspase-8 activity in the nucleus to override the G2/M cell cycle checkpoint. Caspase-8 is upregulated and localized to the nucleus in multiple cancer types correlating with treatment resistance and poor outcome of patients. Nuclear caspase-8 fuels cancer progression by promoting mitosis of cells that are normally paralyzed and/or executed at the G2/M checkpoint in a p53-dependent manner. In the nucleus, caspase-8 cleaves and inactivates the ubiquitin-specific peptidase 28 (USP28) thereby preventing stabilization of p53. This event leads to de facto p53 protein loss, switching cell fate from G2/M arrest and apoptosis towards mitotic cell division. Our work identifies a non-apoptotic role for caspase-8 employed by cancer cells to overcome the p53-dependent G2/M checkpoint and provides a rationale targeting caspase-8 in p53 proficient cancers.
Thursday JUNE 10th – 9:00AM-11:30 AM
SESSION 5: “Glorious uncertainties of Life: Self-eating and Self-preservation”
Chair: Shazib Pervaiz, Univ. Singapore, Singapore
Franck Oury, INSERM/Univ. Paris, France., “Autophagy promotes hippocampal functions and prevents aging-associated cognitive decline”
Matthew Davids, Dana Farber Cancer Institute, USA., “Venetoclax resistance in CLL”
Short Talk – Diede Houbaert, KU Leuven-VIB, Belgium, “The role of lymphatic endothelial autophagy in lymph node T cell trafficking”
Diede Houbaert, Odeta Meçe, Maarten Ganne, Marco BE Schaaf, Hannelore Maes, Patrizia Agostinis
1 Cell Death Research and Therapy (CDRT) Laboratory, Department of Cellular and Molecular Medicine,
KU Leuven-VIB, Belgium
Recent in vivo studies highlight an emerging role for endothelial cell-associated autophagy in the remodelling of the tumor vasculature and cancer cell dissemination. Melanoma cells can use both the blood and the lymphatic vascular systems as channels for metastatic spreading. Aside from that, the lymph nodes are a specialized niche in the generation of immune responses, through recruitment of lymphocytes and their subsequent activation by antigen presenting cells. However, nothing is known about the role of lymphatic endothelial cell (LEC) autophagy in melanoma dissemination and anti-tumor responses. To clarify the specific contribution of LEC-associated autophagy in tumor progression, we generated a transgenic mouse model, whereby ATG5 is deleted specifically in LEC (ATG5LEC-KO). Our preliminary data indicate that genetic deficiency of ATG5 in LEC, reduces intratumoral lymphangiogenesis and causes accumulation of naïve CD4+ and CD8+ T cells in the sentinel lymph node (LNs) of the melanoma bearing mice. Mechanistically we found that LEC-associated autophagy remodels lipid metabolism and regulates the secretion of the sphingosine-1-phosphate (S1P), a crucial lipid mediator regulating T cell trafficking and egress of T cells from LNs. None of these effects are phenocopied by the genetic deletion of ATG5 in the blood EC. These in vivo results support the hypothesis that LEC-autophagy by remodelling lipid metabolism has a profound impact on the tumor microenvironment and the secondary lymphoid organs involved in T cells responses. Experiments are ongoing to elucidate the mechanistic and signalling aspects of autophagy inhibition in the lymphatic vasculature and the in vivo impact on melanoma-induced lymphangiogenesis and antitumor immunity.
Short Talk – Lyndsey Flanagan, RCSI, Dublin, Ireland, “ABT-199 and epigenetic modifiers: promising novel combinations for the treatment of multiple myeloma”
ABT-199 and epigenetic modifiers: promising novel combinations for the treatment of Multiple Myeloma
Lyndsey Flanagan1, Michael O’Dwyer2, John Quinn3, Siobhan Glavey3 and Tríona Ní Chonghaile1
1Dept. of Physiology and Medical Physics, RCSI, Dublin.
2Apoptosis Research Centre, National University of Ireland Galway and Dept. of
Haematology, Galway University Hospital, Galway, Ireland
3Dept. of Haematology, Beaumont Hospital, Dublin 9
Multiple Myeloma (MM) is a malignancy of the antibody-producing plasma cells. Despite vast improvements to treatment, it remains an incurable and fatal disease(1). Therefore, novel innovative therapies are needed for relapsed/refractory MM.
The anti-apoptotic BCL-2 family of proteins (BCL-2, BCL-XL and MCL-1) are critical regulators of the intrinsic apoptotic pathway and determine the survival of human MM cells(2, 3). Therefore, the anti-apoptotic BCL-2 proteins represent attractive therapeutic targets in MM. Recently, ABT-199, a selective BCL-2 inhibitor, was FDA approved. The aim of the study is to develop a biomarker to identify MM samples that are reliant on BCL-2 and could be treated with ABT-199. In addition, we aim to identify novel combination treatments that will induce BCL-2 dependence in MM cells, enhancing sensitivity to ABT-199 treatment. To assess anti-apoptotic dependence, we used BH3 profiling, a functional assay that interrogates BCL-2 protein interactions using synthetic BH3 peptides to measure the loss of mitochondrial membrane potential. We screened a panel of BH3 mimetics in MM cells and patient bone marrow samples; ABT-199 (selective BCL-2 inhibitor), ABT-263 (BCL-2, BCL-xL and BCL-W inhibitor), WEHI-539 (BCL-XL inhibitor) and AMG-176 (selective MCL-1 inhibitor). The BH3 profile data and BH3 mimetics sensitivity data revealed that there is a diverse anti-apoptotic dependence in MM cell lines and primary patient samples.
Next, we performed a small molecule screen to identify epigenetic modifiers that could induce BCL-2 dependence in two MM cell lines. The screen included the following classes of epigenetic drugs: histone deacetylase inhibitors, histone methyltransferase inhibitors, DNA methyltransferase inhibitors and BET inhibitors. Interestingly, two classes of the epigenetic drugs, were synergistic with ABT-199 in two MM cell lines, (CI <0.8). We have also validated both combinations in a third MM cell line. Furthermore, we confirmed enhanced cell death following both ABT-199 and the two classes of epigenetic drugs in two patient MM samples ex-vivo. Future work will focus on determining the mechanism of enhanced cell death induced by the epigenetic drugs to improve the response to ABT-199 treatment.
- O. Landgren, B. M. Weiss, in Leukemia. (England, 2009), vol. 23, pp. 1691-1697.
- A. Letai, M. D. Sorcinelli, C. Beard, S. J. Korsmeyer, Antiapoptotic BCL-2 is required for maintenance of a model leukemia. Cancer Cell 6, 241-249 (2004).
- V. Del Gaizo Moore, K. D. Schlis, S. E. Sallan, S. A. Armstrong, A. Letai, BCL-2 dependence and ABT-737 sensitivity in acute lymphoblastic leukemia. Blood 111, 2300-2309 (2008).
Short Talk – Sahra Aras, Koç University, Turkey, “Regulation of cancer dormancy by microRNAs”
Regulation of cancer dormancy by microRNAs
Sahra Aras1,2*, Sukriye Bilir1,2*, Devrim Gozuacik 1,2,3†
1 Koc University School of Medicine, Istanbul, Turkey
2 Koc University Research Center for Translational Medicine (KUTTAM), Istanbul, Turkey
3 SUNUM Nanotechnology Research and Application Center, Istanbul, Turkey
* These authors have contributed equally to this work
† Correspondence: Prof. Devrim Gozuacik, MD PhD, e-mail: firstname.lastname@example.org
Tumors recurrence after cancer treatment accounts for the vast majority of cancer-related deaths. Cancer dormancy is an important mechanism involved in cancer metastasis and recurrence. Dormant cells stay in a quiescence-like state for months or even years, and when they reactivate, more aggressive and treatment-resistant tumors are formed. Cellular mechanims of dormancy are being explored. The role of microRNAs in the dormant cancer cell behaviour is not clear. In our lab, we established in vitro models of cancer dormancy. A comparative miRNASeq analysis of actively dividing cancer cells and their dormant conterparts revealed a list of dormancy-associated microRNAs. Analysis of potential targets of these microRNAs, showed that, they were involved in cell survival, metabolism, cell cycle, metastasis and autophagy pathways. Our results underline the importance of microRNAs in the regulation of dormant tumor behaviour. Hence, study of dormancy-associated microRNAs will allow a better understanding of the molecular pathways of cancer dormancy, chemotherapy resistance and recurrence, and contribute to the development of new diagnosis, follow-up and treatment strategies.
- Akkoc Y, Peker N, Akcay A and Gozuacik D (2021) Autophagy and Cancer Dormancy. Oncol.11:627023. doi: 10.3389/fonc.2021.627023
Laura Attardi, Stanford Univ., USA., “Understanding the role of p53-driven cell death in developmental syndromes”