CIAP1 regulates the EGFR/Snai2 axis in triple negative breast cancer cells
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ABSTRACT: Inhibitor of apoptosis (IAP) proteins constitute a conserved family of molecules which regulate both apoptosis and receptor signaling. They are often deregulated in cancer cells and represent potential targets for therapy. In our work, we investigated the effect of IAP inhibition in vivo to identify novel downstream genes expressed in an IAP-dependent manner that could contribute to cancer aggressiveness. To this end, immunocompromised mice engrafted subcutaneously with the triple negative breast cancer MDA-MB231 cell line were treated with SM83, a pan-IAP inhibitor developed by us, and tumor nodules were profiled for gene expression. Our work suggests that IAP-targeted therapy could contribute to EGFR inhibition and the reduction of its downstream mediators. This approach could be particularly effective in cells characterized by high levels of EGFR and Snai2, such as triple negative breast cancer.
Project description:Inhibitor of apoptosis (IAP) proteins constitute a family of conserved molecules that regulate both apoptosis and receptor signaling. They are often deregulated in cancer cells and represent potential targets for therapy. In our work, we investigated the effect of IAP inhibition in vivo to identify novel downstream genes expressed in an IAP-dependent manner that could contribute to cancer aggressiveness. To this end, immunocompromised mice engrafted subcutaneously with the triple-negative breast cancer MDA-MB231 cell line were treated with SM83, a Smac mimetic that acts as a pan-IAP inhibitor, and tumor nodules were profiled for gene expression. SM83 reduced the expression of Snai2, an epithelial-to-mesenchymal transition factor often associated with increased stem-like properties and metastatic potential especially in breast cancer cells. By testing several breast cancer cell lines, we demonstrated that Snai2 downregulation prevents cell motility and that its expression is promoted by cIAP1. In fact, the chemical or genetic inhibition of cIAP1 blocked epidermal growth factor receptor (EGFR)-dependent activation of the mitogen-activated protein kinase (MAPK) pathway and caused the reduction of Snai2 transcription levels. In a number of breast cancer cell lines, cIAP1 depletion also resulted in a reduction of EGFR protein levels which derived from the decrease of its gene transcription, though, paradoxically, the silencing of cIAP1 promoted EGFR protein stability rather than its degradation. Finally, we provided evidence that IAP inhibition displays an anti-tumor and anti-metastasis effect in vivo. In conclusion, our work indicates that IAP-targeted therapy could contribute to EGFR inhibition and to the reduction of its downstream mediators. This approach could be particularly effective in tumors characterized by high levels of EGFR and Snai2, such as triple-negative breast cancer.
Project description:Goal of this study was to investigate the time-dependent impact of ONC201 on gene expression changes in MDA-MB231, a triple negative breast cancer cell line
Project description:Systems modelling of the EGFR-PYK2-c-Met interaction network predicted and prioritized synergistic drug combinations for Triple-negative breast cancer
Project description:Checkpoint blockade immunotherapy has failed in pancreatic cancer and other poorly responsive tumor types in part due to inadequate T cell priming. Naïve T cells can receive co-stimulation not only via CD28 but also through TNF superfamily receptors that signal via NF-κB. Antagonists of the ubiquitin ligases cIAP1/2, also called SMAC mimetics, induce degradation of cIAP1/2 proteins, allowing for the accumulation of NIK and constitutive, ligand-independent activation of alternate NF-κB signaling that mimics co-stimulation in T cells. In tumor cells, cIAP1/2 antagonists can increase TNF production and TNF-mediated apoptosis; however, pancreatic cancer cells are resistant to cytokine-mediated apoptosis, even in the presence of cIAP1/2 antagonism. Here, we confirm our previous findings that even poorly immunogenic tumors with a paucity of T cells can experience T cell-dependent anti-tumor immunity, and we provide transcriptional clues into how these rare T cells coordinate downstream immune responses.
Project description:Induction of non-canonical NF-kB signaling with IAP antagonists mimics costimulatory signaling, augmenting anti-tumor immunity. We now show that induction of non-canonical NF-kB signaling induces T-cell dependent immune responses even in B2M-null tumors, demonstrating that direct CD8 T cell recognition of tumor cell expressed MHC class I is not required. Instead, T cell-produced cytokines reprogram macrophages to be tumoricidal. In wildtype mice IAP antagonism reduces tumor burden by increasing phagocytosis of tumor cells. We characterized by RNA-Seq the transcriptional profile of intratumoral phagocytes with and without treatment with the IAP antagonist LCL161.
Project description:Induction of non-canonical NF-kB signaling with IAP antagonists mimics costimulatory signaling, augmenting anti-tumor immunity. We show that induction of non-canonical NF-kB signaling induces T-cell dependent immune responses even in B2M-null tumors, demonstrating that direct CD8 T cell recognition of tumor cell expressed MHC class I is not required. Instead, T cell-produced cytokines reprogram macrophages to be tumoricidal. In wildtype mice, IAP antagonism reduces tumor burden by increasing phagocytosis of tumor cells. We characterized by RNA-Seq the transcriptional response of macrophages to T-cell produced lymphotoxin (LT) in the presence or absence of the IAP antagonist LCL161.
Project description:Experiments to test the effect of CtBP2 inhibition on metabolism of breast cell lines. In particular, experiment 1 involves comparison between a normal breast cell line (MCF102A) and a triple-negative breast cancer cell line (MDA-MB231). Experiment 2 is a study between MDA-MB231 silenced for CtBP2 by stable RNA interference (shCtBP2 cells) compared to scramble (shCTRL cells). Experiment 3 is a comparison between a normal breast cell line (MCF102A) and a triple-negative breast cancer cell line (MDA-MB231)in the presence of the absence of small-molecule CtBP inhibitors: HIPP (400 μM) or P4 (300 μM)for 48 hours.
Project description:Jörg W. Stucki & Hans-Uwe Simon. Mathematical modeling of the regulation of caspase-3 activation and degradation. Journal of Theoretical Biology 234, 1 (2005).
Caspases are thought to be important players in the execution process of apoptosis. Inhibitors of apoptosis (IAPs) are able to block caspases and therefore apoptosis. The fact that a subgroup of the IAP family inhibits active caspases implies that not each caspase activation necessarily leads to apoptosis. In such a scenario, however, processed and enzymically active caspases should somehow be removed. Indeed, IAP–caspase complexes covalently bind ubiquitin, resulting in degradation by the 26S proteasome. Following release from mitochondria, IAP antagonists (e.g. second mitochondrial activator of caspases (Smac)) inactivate IAPs. Moreover, although pro-apoptotic factors such as irradiation or anti-cancer drugs may release Smac from mitochondria in tumor cells, high cytoplasmic survivin and ML-IAP levels might be able to neutralize it and, consequently, IAPs would further be able to bind activated caspases. Here, we propose a simple mathematical model, describing the molecular interactions between Smac deactivators, Smac, IAPs, and caspase-3, including the requirements for both induction and prevention of apoptosis, respectively. In addition, we predict a novel mechanism of caspase-3 degradation that might be particularly relevant in long-living cells.
Project description:Induction of non-canonical NF-kB signaling with IAP antagonists mimics costimulatory signaling, augmenting anti-tumor immunity. We show that induction of non-canonical NF-kB signaling induces T-cell dependent immune responses even in B2M-null tumors, demonstrating that direct CD8 T cell recognition of tumor cell expressed MHC class I is not required. Instead, T cell-produced cytokines reprogram macrophages to be tumoricidal. We characterized by single-cell RNA-Seq the transcriptional profile of immune cells infilitrating mouse pancreatic tumors treated with the IAP anatagonist LCL161.