@article{91a561dff58340c7b51e490dce4416fc,
title = "Hypoxia-induced autophagy drives colorectal cancer initiation and progression by activating the PRKC/PKC-EZR (ezrin) pathway",
abstract = "In solid tumors, cancer stem cells (CSCs) or tumor-initiating cells (TICs) are often found in hypoxic niches. Nevertheless, the influence of hypoxia on TICs is poorly understood. Using previously established, TIC-enrichedpatient-derived colorectal cancer (CRC) cultures, we show that hypoxia increases the self-renewal capacity of TICs while inducing proliferation arrest in their more differentiated counterpart cultures. Gene expression data revealed macroautophagy/autophagy as one of the major pathways induced by hypoxia in TICs. Interestingly, hypoxia-induced autophagy was found to induce phosphorylation of EZR (ezrin) at Thr567 residue, which could be reversed by knocking down ATG5, BNIP3, BNIP3L, or BECN1. Furthermore, we identified PRKCA/PKCα as a potential kinase involved in hypoxia-induced autophagy-mediated TIC self-renewal. Genetic targeting of autophagy or pharmacological inhibition of PRKC/PKC and EZR resulted in decreased tumor-initiating potential of TICs. In addition, we observed significantly reduced in vivo tumor initiation and growth after a stable knockdown of ATG5. Analysis of human CRC samples showed that p-EZR is often present in TICs located in the hypoxic and autophagic regions of the tumor. Altogether, our results establish the hypoxia-autophagy-PKC-EZR signaling axis as a novel regulatory mechanism of TIC self-renewal and CRC progression. Autophagy inhibition might thus represent a promising therapeutic strategy for cancer patients. Abbreviations: ATG: autophagy related; BECN1: beclin 1; BNIP3: BCL2 interacting protein 3; BNIP3L: BCL2 interacting protein 3 like; CQ: chloroquine; CSC: cancer stem cells; CRC: colorectal cancer; HIF1A/HIF-1α: hypoxia inducible factor 1 subunit alpha; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; PRKC/PKC: protein kinase C; SQSTM1/p62: sequestosome 1; TICs: tumor-initiating cells.",
keywords = "Autophagy, cancer stem cell, colorectal cancer, ezrin, hypoxia, protein kinase C, self-renewal capacity, tumor-initiating cell",
author = "Komal Qureshi-Baig and Diana Kuhn and Elodie Viry and Pozdeev, {Vitaly I.} and Martine Schmitz and Fabien Rodriguez and Pit Ullmann and Eric Koncina and Martin Nurmik and Sonia Frasquilho and Nazarov, {Petr V.} and Nikolaus Zuegel and Marc Boulmont and Yervand Karapetyan and Laurent Antunes and Daniel Val and Michel Mittelbronn and Bassam Janji and Serge Haan and Elisabeth Letellier",
note = "Funding Information: We would like to thank all the contributing surgeons and nurses from the Centre Hospitalier du Luxembourg, the Centre Hospitalier Emile Mayrisch and the Clinical and Epidemiological Investigation Centre of the Luxembourg Institute of Health (LIH) for their work with the patients. The authors would also like to thank their collaborators at the Integrated Biobank of Luxembourg (IBBL), particularly Dr. Fay Betsou and Dr. Nikolai Goncharenko for the overall set-up of the patient sample collection and RNA extraction. We are also grateful to Dr. Djalil Coowar and Dr. Marthe Schmit for managing the animal facility of the University of Luxembourg. We are thankful to all the members of the Genomics Research Unit of the LIH, especially Nathalie Nicot and Arnaud Muller, as well as Aur{\'e}lien Ginolhac from the Bioinformatic Core Facility at the University of Luxembourg for performing the microarray experiments and/or for providing bioinformatics support. We would also like to thank Associate Professor Paul Wilmes for access to his microscope facility. Finally, we would like to thank Dr. Christelle Bahlawane from the IBBL for her assistance and invaluable input in critical discussions. MM would like to thank the Luxembourg National Research Fund for the support (FNR Pearl P16/BM/11192868). Funding Information: This project was supported by the TELEVIE (28504270, R-AGR-3140) and Fondation Cancer (grant F1R-LSC-PAU-13HY2C) and Janssen Cilag. Dr. Komal Qureshi-Baig, Dr. Pit Ullmann and Martin Nurmik are supported by the Fonds National de la Recherche (FNR) (under the AFR grant scheme and PRIDE scheme) and by the Fondation du P?lican de Mie and Pierre Hippert-Faber under the aegis of the Fondation de Luxembourg. EV is supported by a TELEVIE grant (7456517, R-AGR-3377). EL is supported by a CORE (C16/BM/11282028) and a POC grant (PoC18/12554295). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. We would like to thank all the contributing surgeons and nurses from the Centre Hospitalier du Luxembourg, the Centre Hospitalier Emile Mayrisch and the Clinical and Epidemiological Investigation Centre of the Luxembourg Institute of Health (LIH) for their work with the patients. The authors would also like to thank their collaborators at the Integrated Biobank of Luxembourg (IBBL), particularly Dr. Fay Betsou and Dr. Nikolai Goncharenko for the overall set-up of the patient sample collection and RNA extraction. We are also grateful to Dr. Djalil Coowar and Dr. Marthe Schmit for managing the animal facility of the University of Luxembourg. We are thankful to all the members of the Genomics Research Unit of the LIH, especially Nathalie Nicot and Arnaud Muller, as well as Aur?lien Ginolhac from the Bioinformatic Core Facility at the University of Luxembourg for performing the microarray experiments and/or for providing bioinformatics support. We would also like to thank Associate Professor Paul Wilmes for access to his microscope facility. Finally, we would like to thank Dr. Christelle Bahlawane from the IBBL for her assistance and invaluable input in critical discussions. MM would like to thank the Luxembourg National Research Fund for the support (FNR Pearl P16/BM/11192868). Publisher Copyright: {\textcopyright} 2019 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.",
year = "2020",
month = aug,
day = "2",
doi = "10.1080/15548627.2019.1687213",
language = "English",
volume = "16",
pages = "1436--1452",
journal = "Autophagy",
issn = "1554-8627",
publisher = "Landes Bioscience",
number = "8",
}