Non-Canonical Hedgehog Signaling Is a Positive Regulator of the WNT Pathway and Is Required for the Survival of Colon Cancer Stem Cells
Joseph L. Regan,
Dirk Schumacher,
Stephanie Staudte,
Andreas Steffen,
Johannes Haybaeck,
Ulrich Keilholz,
Caroline Schweiger,
Nicole Golob-Schwarzl,
Dominik Mumberg,
David Henderson,
Hans Lehrach,
Christian R.A. Regenbrecht,
Reinhold Schäfer,
Martin Lange
Affiliations
Joseph L. Regan
Bayer AG, Drug Discovery, Pharmaceuticals, 13342 Berlin, Germany; Charité Comprehensive Cancer Center, Charité – Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany; Corresponding author
Dirk Schumacher
Laboratory of Molecular Tumor Pathology, Charité Universitätsmedizin Berlin, 10117 Berlin, Germany; German Cancer Consortium (DKTK), DKFZ, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
Stephanie Staudte
Bayer AG, Drug Discovery, Pharmaceuticals, 13342 Berlin, Germany; Charité Comprehensive Cancer Center, Charité – Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
Andreas Steffen
Bayer AG, Drug Discovery, Pharmaceuticals, 13342 Berlin, Germany
Johannes Haybaeck
Department of Pathology, Medical Faculty, Otto von Guericke University Magdeburg, Leipziger Straße 44, Haus 28, 39120 Magdeburg, Germany; Institute of Pathology, Medical University Graz, Auenbruggerplatz 25, 8036 Graz, Austria
Ulrich Keilholz
Charité Comprehensive Cancer Center, Charité – Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
Caroline Schweiger
Institute of Pathology, Medical University Graz, Auenbruggerplatz 25, 8036 Graz, Austria
Nicole Golob-Schwarzl
Institute of Pathology, Medical University Graz, Auenbruggerplatz 25, 8036 Graz, Austria
Dominik Mumberg
Bayer AG, Drug Discovery, Pharmaceuticals, 13342 Berlin, Germany
David Henderson
Bayer AG, Drug Discovery, Pharmaceuticals, 13342 Berlin, Germany
Hans Lehrach
Max Planck Institute for Molecular Genetics, Ihnestrasse 73, 14195 Berlin, Germany
Summary: Colon cancer is a heterogeneous tumor driven by a subpopulation of cancer stem cells (CSCs). To study CSCs in colon cancer, we used limiting dilution spheroid and serial xenotransplantation assays to functionally define the frequency of CSCs in a panel of patient-derived cancer organoids. These studies demonstrated cancer organoids to be enriched for CSCs, which varied in frequency between tumors. Whole-transcriptome analysis identified WNT and Hedgehog signaling components to be enhanced in CSC-enriched tumors and in aldehyde dehydrogenase (ALDH)-positive CSCs. Canonical GLI-dependent Hedgehog signaling is a negative regulator of WNT signaling in normal intestine and intestinal tumors. Here, we show that Hedgehog signaling in colon CSCs is autocrine SHH-dependent, non-canonical PTCH1 dependent, and GLI independent. In addition, using small-molecule inhibitors and RNAi against SHH-palmitoylating Hedgehog acyltransferase (HHAT), we demonstrate that non-canonical Hedgehog signaling is a positive regulator of WNT signaling and required for colon CSC survival. : Colon cancer is a heterogeneous tumor driven by a subpopulation(s) of therapy-resistant cancer stem cells (CSCs). Regan et al. use 3D culture models to demonstrate that CSC survival is regulated by non-canonical, SHH-dependent, PTCH1-dependent Hedgehog signaling, which acts as a positive regulator of WNT signaling to block CSC differentiation. Keywords: WNT pathway, non-canonical Hedgehog signaling, cancer stem cell, colon cancer, cancer organoid, PTCH1, HHAT, SHH
