MCL1 is Required for Maintenance of Intestinal Homeostasis and Prevention of Carcinogenesis in Mice

BACKGROUND & AIMS Intestinal epithelial homeostasis depends on a tightly regulated balance between intestinal epithelial cell (IEC) death and proliferation. Disruption of factors that promote IEC death result in intestinal inflammation, whereas loss of anti-apoptotic proteins, such as BCL2 or its family member BCL2L1, has no effect on intestinal homeostasis in mice. We investigated the functions of the anti-apoptotic protein MCL1, another member of the BCL2 family, in intestinal homeostasis in mice. METHODS We generated mice with IEC-specific disruption of Mcl1 (Mcl1$^{ΔIEC}$ mice) or tamoxifen-inducible IEC-specific disruption of Mcl1 (i-Mcl1$^{ΔIEC}$ mice); these mice and mice with full-length Mcl1 (controls) were raised under normal or germ-free conditions. Some mice were given antibiotics in their drinking water or the PORCUPINE WNT inhibitor WNT974. Mice were analyzed by endoscopy and for intestinal epithelial barrier permeability. Intestinal tissues were analyzed by histology, in situ hybridization, proliferation assays, and immunoblots. Levels of calprotectin, a marker of intestinal inflammation, were measured in intestinal tissues and feces. RESULTS Mcl1$^{ΔIEC}$ mice spontaneously developed apoptotic enterocolopathy, characterized by increased IEC apoptosis, hyperproliferative crypts, epithelial barrier dysfunction, and chronic inflammation. Loss of MCL1 retained intestinal crypts in a hyperproliferated state and prevented the differentiation of intestinal stem cells. Proliferation of intestinal stem cells in MCL1-deficient mice required WNT signaling and was associated with DNA damage accumulation. By 1 year of age, Mcl1$^{ΔIEC}$ mice developed intestinal tumors with morphologic and genetic features of human adenomas and carcinomas. Germ-free housing of Mcl1$^{ΔIEC}$ mice reduced markers of microbiota-induced intestinal inflammation but not tumor development. CONCLUSION The anti-apoptotic protein MCL1, a member of the BCL2 family, is required for maintenance of intestinal homeostasis and prevention of carcinogenesis in mice. Loss of MCL1 results in development of intestinal carcinomas, even under germ-free conditions, and therefore does not involve microbe-induced chronic inflammation. Mcl1$^{ΔIEC}$ mice might be used to study apoptotic enterocolopathy and inflammatory bowel diseases

A Dual Role of Caspase-8 in Triggering and Sensing Proliferation-Associated DNA Damage, a Key Determinant of Liver Cancer Development

Concomitant hepatocyte apoptosis and regeneration is a hallmark of chronic liver diseases (CLDs) predisposing to hepatocellular carcinoma (HCC). Here, we mechanistically link caspase-8-dependent apoptosis to HCC development via proliferation- and replication-associated DNA damage. Proliferation-associated replication stress, DNA damage, and genetic instability are detectable in CLDs before any neoplastic changes occur. Accumulated levels of hepatocyte apoptosis determine and predict subsequent hepatocarcinogenesis. Proliferation-associated DNA damage is sensed by a complex comprising caspase-8, FADD, c-FLIP, and a kinase-dependent function of RIPK1. This platform requires a non-apoptotic function of caspase-8, but no caspase-3 or caspase-8 cleavage. It may represent a DNA damage-sensing mechanism in hepatocytes that can act via JNK and subsequent phosphorylation of the histone variant H2AX

Platelet GPIbα is a mediator and potential interventional target for NASH and subsequent liver cancer

Non-alcoholic fatty liver disease ranges from steatosis to non-alcoholic steatohepatitis (NASH), potentially progressing to cirrhosis and hepatocellular carcinoma (HCC). Here, we show that platelet number, platelet activation and platelet aggregation are increased in NASH but not in steatosis or insulin resistance. Antiplatelet therapy (APT; aspirin/clopidogrel, ticagrelor) but not nonsteroidal anti-inflammatory drug (NSAID) treatment with sulindac prevented NASH and subsequent HCC development. Intravital microscopy showed that liver colonization by platelets depended primarily on Kupffer cells at early and late stages of NASH, involving hyaluronan-CD44 binding. APT reduced intrahepatic platelet accumulation and the frequency of platelet-immune cell interaction, thereby limiting hepatic immune cell trafficking. Consequently, intrahepatic cytokine and chemokine release, macrovesicular steatosis and liver damage were attenuated. Platelet cargo, platelet adhesion and platelet activation but not platelet aggregation were identified as pivotal for NASH and subsequent hepatocarcinogenesis. In particular, platelet-derived GPIbα proved critical for development of NASH and subsequent HCC, independent of its reported cognate ligands vWF, P-selectin or Mac-1, offering a potential target against NASH

Chemical hybridization of glucagon and thyroid hormone optimizes therapeutic impact for metabolic disease

Glucagon and thyroid hormone (T3) exhibit therapeutic potential for metabolic disease but also exhibit undesired effects. We achieved synergistic effects of these two hormones and mitigation of their adverse effects by engineering chemical conjugates enabling delivery of both activities within one precisely targeted molecule. Coordinated glucagon and T3 actions synergize to correct hyperlipidemia, steatohepatitis, atherosclerosis, glucose intolerance, and obesity in metabolically compromised mice. We demonstrate that each hormonal constituent mutually enriches cellular processes in hepatocytes and adipocytes via enhanced hepatic cholesterol metabolism and white fat browning. Synchronized signaling driven by glucagon and T3 reciprocally minimizes the inherent harmful effects of each hormone. Liver-directed T3 action offsets the diabetogenic liability of glucagon, and glucagon-mediated delivery spares the cardiovascular system from adverse T3 action. Our findings support the therapeutic utility of integrating these hormones into a single molecular entity that offers unique potential for treatment of obesity, type 2 diabetes, and cardiovascular disease

Chemical hybridization of glucagon and thyroid hormone optimizes therapeutic impact for metabolic disease

Glucagon and thyroid hormone (T3) exhibit therapeutic potential for metabolic disease but also exhibit undesired effects. We achieved synergistic effects of these two hormones and mitigation of their adverse effects by engineering chemical conjugates enabling delivery of both activities within one precisely targeted molecule. Coordinated glucagon and T3 actions synergize to correct hyperlipidemia, steatohepatitis, atherosclerosis, glucose intolerance, and obesity in metabolically compromised mice. We demonstrate that each hormonal constituent mutually enriches cellular processes in hepatocytes and adipocytes via enhanced hepatic cholesterol metabolism and white fat browning. Synchronized signaling driven by glucagon and T3 reciprocally minimizes the inherent harmful effects of each hormone. Liver-directed T3 action offsets the diabetogenic liability of glucagon, and glucagon-mediated delivery spares the cardiovascular system from adverse T3 action. Our findings support the therapeutic utility of integrating these hormones into a single molecular entity that offers unique potential for treatment of obesity, type 2 diabetes, and cardiovascular disease

Epitope spreading toward wild-type melanocyte-lineage antigens rescues suboptimal immune checkpoint blockade responses

Although immune checkpoint inhibitors (ICIs), such as anti-programmed cell death protein-1 (PD-1), can deliver durable antitumor effects, most patients with cancer fail to respond. Recent studies suggest that ICI efficacy correlates with a higher load of tumor-specific neoantigens and development of vitiligo in patients with melanoma. Here, we report that patients with low melanoma neoantigen burdens who responded to ICI had tumors with higher expression of pigmentation-related genes. Moreover, expansion of peripheral blood CD8+ T cell populations specific for melanocyte antigens was observed only in patients who responded to anti-PD-1 therapy, suggesting that ICI can promote breakdown of tolerance toward tumor-lineage self-antigens. In a mouse model of poorly immunogenic melanomas, spreading of epitope recognition toward wild-type melanocyte antigens was associated with markedly improved anti-PD-1 efficacy in two independent approaches: introduction of neoantigens by ultraviolet (UV) B radiation mutagenesis or the therapeutic combination of ablative fractional photothermolysis plus imiquimod. Complete responses against UV mutation-bearing tumors after anti-PD-1 resulted in protection from subsequent engraftment of melanomas lacking any shared neoantigens, as well as pancreatic adenocarcinomas forcibly overexpressing melanocyte-lineage antigens. Our data demonstrate that somatic mutations are sufficient to provoke strong antitumor responses after checkpoint blockade, but long-term responses are not restricted to these putative neoantigens. Epitope spreading toward T cell recognition of wild-type tumor-lineage self-antigens represents a common pathway for successful response to ICI, which can be evoked in neoantigen-deficient tumors by combination therapy with ablative fractional photothermolysis and imiquimod

A Dual Role of Caspase-8 in Triggering and Sensing Proliferation-Associated DNA Damage, a Key Determinant of Liver Cancer Development

Concomitant hepatocyte apoptosis and regeneration is a hallmark of chronic liver diseases (CLDs) predisposing to hepatocellular carcinoma (HCC). Here, we mechanistically link caspase-8-dependent apoptosis to HCC development via proliferation- and replication-associated DNA damage. Proliferation-associated replication stress, DNA damage, and genetic instability are detectable in CLDs before any neoplastic changes occur. Accumulated levels of hepatocyte apoptosis determine and predict subsequent hepatocarcinogenesis. Proliferation-associated DNA damage is sensed by a complex comprising caspase-8, FADD, c-FLIP, and a kinase-dependent function of RIPK1. This platform requires a non-apoptotic function of caspase-8, but no caspase-3 or caspase-8 cleavage. It may represent a DNA damage-sensing mechanism in hepatocytes that can act via JNK and subsequent phosphorylation of the histone variant H2AX.ISSN:1535-6108ISSN:1878-368

Platelet GPIbα is a mediator and potential interventional target for NASH and subsequent liver cancer

Non-alcoholic fatty liver disease ranges from steatosis to non-alcoholic steatohepatitis (NASH), potentially progressing to cirrhosis and hepatocellular carcinoma (HCC). Here, we show that platelet number, platelet activation and platelet aggregation are increased in NASH but not in steatosis or insulin resistance. Antiplatelet therapy (APT; aspirin/clopidogrel, ticagrelor) but not nonsteroidal anti-inflammatory drug (NSAID) treatment with sulindac prevented NASH and subsequent HCC development. Intravital microscopy showed that liver colonization by platelets depended primarily on Kupffer cells at early and late stages of NASH, involving hyaluronan-CD44 binding. APT reduced intrahepatic platelet accumulation and the frequency of platelet-immune cell interaction, thereby limiting hepatic immune cell trafficking. Consequently, intrahepatic cytokine and chemokine release, macrovesicular steatosis and liver damage were attenuated. Platelet cargo, platelet adhesion and platelet activation but not platelet aggregation were identified as pivotal for NASH and subsequent hepatocarcinogenesis. In particular, platelet-derived GPIbα proved critical for development of NASH and subsequent HCC, independent of its reported cognate ligands vWF, P-selectin or Mac-1, offering a potential target against NASH.We thank D. Heide, J. Hetzer, R. Hillermann, C. Gropp, F. Muller, S. Prokosch, D. Kull, R. Dunkl, O. Seelbach, M. Bawohl, R. Maire, M. Bieri, C. Mittmann, H. HoncharovaBiletska, A. Fitsche, A. Adili, P. Munzer, T. Nussbaumer, F. Prutek, G. Dharmalingam and I. Singh for excellent technical assistance. We thank K. Nikolaou for the help with the human cohort recruitment and analysis. M. Malehmir was partially supported by grants from the University Zurich (Zurich Integrative Human Physiology (ZHIP) Sprint Fellowship) and from the Hartmann Muller Stiftung, Zurich. A.W. was supported by a grant from the Swiss National Science Foundation (320030_182764/1). M. Heikenwaelder was supported by an ERC Consolidator grant (HepatoMetaboPath), an EOS grant, SFBTR 209, SFBTR179, Research Foundation Flanders (FWO) under grant 30826052 (EOS Convention MODEL-IDI), Deutsche Krebshilfe projects 70113166 and 70113167, and the Helmholtz-Gemeinschaft, Zukunftsthema 'Immunology and Inflammation' (ZT-0027). This project has received funding from the European Union's Horizon 2020 research and innovation program under grant agreement 667273 and the DFG (SFB/TR 240 (project 374031971) to B.N. and D. S.), ERC Consolidator grant 'CholangioConcept' (to L.Z.), and the German Research Foundation (DFG): grants FOR2314, SFB685 and the Gottfried Wilhelm Leibniz Program (to L.Z.). Further funding was provided by the German Ministry for Education and Research (BMBF) (eMed/Multiscale HCC), the German Universities Excellence Initiative (third funding line: 'future concept'), the German Center for Translational Cancer Research (DKTK) and the German-Israeli Cooperation in Cancer Research (DKFZ-MOST) (to L.Z. and M. Heikenwaelder). D. I. was supported by an EMBO Long-term Fellowship. J.M.L. is supported by Asociacion Espanola Contra el Cancer (Accelerator award: HUNTER), Spanish National Health Institute (SAF2013-41027), Generalitat de Catalunya (SGR 1162 and AGAUR, SGR-1358), the Samuel Waxman Cancer Research Foundation, the US Department of Defense (CA150272P3), the European Commission Horizon 2020 Program (HEPCAR, proposal number 667273-2), and the National Cancer Institute (P30 CA196521). D. A. M. is supported by CRUK grant C18342/A23390 and MRC grant MR/K001949/1. M. P. is supported by the German Research Foundation (DFG). M. G., T. G. and D. R. was supported by grants from the German Research Foundation (KFO274 and SFB/TR240 (project 374031971)). D. J. W. received a Wellcome Trust Strategic Award (098565/Z/12/Z) and funding from the Medical Research Council (MC-A654-5QB40). C.L.W. was funded by CRUK project Cancer Research UK Programme Grant C18342/A23390. H. G. A. has been supported by the Deutsche Forschungsgemeinschaft (SFB-TR209 'Liver Cancer').S