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Author: Ahmed Sadik3
Tryptophan stress activates EGFR-RAS-signaling to MTORC1 and p38/MAPK to sustain translation and AHR-dependent autophagy

Abstract (Expand)

Limited supply and catabolism restrict the essential amino acid tryptophan (Trp) in tumors. How tumors sustain translation under Trp stress remains unclear. Unlike other amino acids, Trp stress activates …s the EGFR, which enhances macropinocytosis and RAS signaling to the MTORC1 and p38/MAPK kinases, sustaining translation. The AHR forms part of the Trp stress proteome and promotes autophagy to sustain Trp levels, and ceramide biosynthesis. Thus, Trp restriction elicits pro-translation signals enabling adaptation to nutrient stress, placing Trp into a unique position in the amino acid-mediated stress response. Our findings challenge the current perception that Trp restriction inhibits MTORC1 and the AHR and explain how both cancer drivers remain active. A glioblastoma patient subgroup with enhanced MTORC1 and AHR displays an autophagy signature, highlighting the clinical relevance of MTORC1-AHR crosstalk. Regions of high Trp or high ceramides are mutually exclusive, supporting that low Trp activates the EGFR-MTORC1-AHR axis in glioblastoma tissue.

Authors: Pauline Pfänder, Lucas Hensen, Patricia Razquin Navas, Marie Solvay, Mirja Tamara Prentzell, Ahmed Sadik, Alexander M. Heberle, Sophie Seifert, Leon Regin, Tobias Bausbacher, Anna-Sophia Egger, Madlen Hotze, Tobias Kipura, Bianca Berdel, Ivana Karabogdan, Luis F. Somarribas Patterson, Michele Reil, Deepak Sayeeram, Vera Peters, Jose Ramos Pittol, Ineke van ’t Land-Kuper, Teresa Börding, Saskia Trump, Alienke van Pijkeren, Yang Zhang, Fabricio Loayza-Puch, Alexander Kowar, Sönke Harder, Lorenz Waltl, André Gollowitzer, Tetsushi Kataura, Viktor I. Korolchuk, Shad A. Mohammed, Phillipp Sievers, Felix Sahm, Hartmut Schlüter, Andreas Koeberle, Carsten Hopf, Marcel Kwiatkowski, Christine Sers, Benoit J. Van den Eynde, Christiane A. Opitz, Kathrin Thedieck

Date Published: 17th Jan 2023

Publication Type: Journal

IL4I1 Is a Metabolic Immune Checkpoint that Activates the AHR and Promotes Tumor Progression

Abstract (Expand)

Aryl hydrocarbon receptor (AHR) activation by tryptophan (Trp) catabolites enhances tumor malignancy and suppresses anti-tumor immunity. The context specificity of AHR target genes has so far impeded … systematic investigation of AHR activity and its upstream enzymes across human cancers. A pan-tissue AHR signature, derived by natural language processing, revealed that across 32 tumor entities, interleukin-4-induced-1 (IL4I1) associates more frequently with AHR activity than IDO1 or TDO2, hitherto recognized as the main Trp-catabolic enzymes. IL4I1 activates the AHR through the generation of indole metabolites and kynurenic acid. It associates with reduced survival in glioma patients, promotes cancer cell motility, and suppresses adaptive immunity, thereby enhancing the progression of chronic lymphocytic leukemia (CLL) in mice. Immune checkpoint blockade (ICB) induces IDO1 and IL4I1. As IDO1 inhibitors do not block IL4I1, IL4I1 may explain the failure of clinical studies combining ICB with IDO1 inhibition. Taken together, IL4I1 blockade opens new avenues for cancer therapy.

Authors: Ahmed Sadik, Luis F. Somarribas Patterson, Selcen Öztürk, Soumya R. Mohapatra, Verena Panitz, Philipp F. Secker, Pauline Pfänder, Stefanie Loth, Heba Salem, Mirja Tamara Prentzell, Bianca Berdel, Murat Iskar, Erik Faessler, Friederike Reuter, Isabelle Kirst, Verena Kalter, Kathrin I. Foerster, Evelyn Jäger, Carina Ramallo Guevara, Mansour Sobeh, Thomas Hielscher, Gernot Poschet, Annekathrin Reinhardt, Jessica C. Hassel, Marc Zapatka, Udo Hahn, Andreas von Deimling, Carsten Hopf, Rita Schlichting, Beate I. Escher, Jürgen Burhenne, Walter E. Haefeli, Naveed Ishaque, Alexander Böhme, Sascha Schäuble, Kathrin Thedieck, Saskia Trump, Martina Seiffert, Christiane A. Opitz

Date Published: 1st Sep 2020

Publication Type: Journal

The PI3K and MAPK/p38 pathways control stress granule assembly in a hierarchical manner

Abstract (Expand)

All cells and organisms exhibit stress-coping mechanisms to ensure survival. Cytoplasmic protein-RNA assemblies termed stress granules are increasingly recognized to promote cellular survival under … stress. Thus, they might represent tumor vulnerabilities that are currently poorly explored. The translationinhibitory eIF2α kinases are established as main drivers of stress granule assembly. Using a systems approach, we identify the translation enhancers PI3K and MAPK/p38 as pro-stressgranule- kinases. They act through the metabolic master regulator mammalian target of rapamycin complex 1 (mTORC1) to promote stress granule assembly.When highly active, PI3K is the main driver of stress granules; however, the impact of p38 becomes apparent as PI3K activity declines. PI3K and p38 thus act in a hierarchical manner to drive mTORC1 activity and stress granule assembly. Of note, this signaling hierarchy is also present in human breast cancer tissue. Importantly, only the recognition of the PI3K-p38 hierarchy under stress enabled the discovery of p38’s role in stress granule formation. In summary, we assign a new prosurvival function to the key oncogenic kinases PI3K and p38, as they hierarchically promote stress granule formation.

Authors: Alexander Martin Heberle, Patricia Razquin Navas, Miriam Langelaar-Makkinje, Katharina Kasack, Ahmed Sadik, Erik Faessler, Udo Hahn, Philip Marx-Stoelting, Christiane A Opitz, Christine Sers, Ines Heiland, Sascha Schäuble, Kathrin Thedieck

Date Published: 28th Mar 2019

Publication Type: Not specified

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