Induction of endoplasmic reticulum stress by deletion of Grp78 depletes Apc mutant intestinal epithelial stem cells.
Intestinal epithelial stem cells are highly sensitive to differentiation induced by endoplasmic reticulum (ER) stress. Colorectal cancer develops from mutated intestinal epithelial stem cells. The most frequent initiating mutation occurs in Apc, which results in hyperactivated Wnt signalling. This causes hyperproliferation and reduced sensitivity to chemotherapy, but whether these mutated stem cells are sensitive to ER stress induced differentiation remains unknown. Here we examined this by generating mice in which both Apc and ER stress repressor chaperone Grp78 can be conditionally deleted from the intestinal epithelium. For molecular studies, we used intestinal organoids derived from these mice. Homozygous loss of Apc alone resulted in crypt elongation, activation of the Wnt signature and accumulation of intestinal epithelial stem cells, as expected. This phenotype was however completely rescued on activation of ER stress by additional deletion of Grp78. In these Apc-Grp78 double mutant animals, stem cells were rapidly lost and repopulation occurred by non-mutant cells that had escaped recombination, suggesting that Apc-Grp78 double mutant stem cells had lost self-renewal capacity. Although in Apc-Grp78 double mutant mice the Wnt signature was lost, these intestines exhibited ubiquitous epithelial presence of nuclear β-catenin. This suggests that ER stress interferes with Wnt signalling downstream of nuclear β-catenin. In conclusion, our findings indicate that ER stress signalling results in loss of Apc mutated intestinal epithelial stem cells by interference with the Wnt signature. In contrast to many known inhibitors of Wnt signalling, ER stress acts downstream of β-catenin. Therefore, ER stress poses a promising target in colorectal cancers, which develop as a result of Wnt activating mutations.
Academic Medical Center, Tygat Institute for Liver and Intestinal Research and Department of Gastroenterology and Hepatology, Amsterdam, The Netherlands.
J F
JF
van Lidth de Jeude
Academic Medical Center, Tygat Institute for Liver and Intestinal Research and Department of Gastroenterology and Hepatology, Amsterdam, The Netherlands.
B J
BJ
Meijer
Academic Medical Center, Tygat Institute for Liver and Intestinal Research and Department of Gastroenterology and Hepatology, Amsterdam, The Netherlands.
M C B
MCB
Wielenga
Academic Medical Center, Tygat Institute for Liver and Intestinal Research and Department of Gastroenterology and Hepatology, Amsterdam, The Netherlands.
C N
CN
Spaan
Academic Medical Center, Tygat Institute for Liver and Intestinal Research and Department of Gastroenterology and Hepatology, Amsterdam, The Netherlands.
B
B
Baan
Academic Medical Center, Tygat Institute for Liver and Intestinal Research and Department of Gastroenterology and Hepatology, Amsterdam, The Netherlands.
S L
SL
Rosekrans
Academic Medical Center, Tygat Institute for Liver and Intestinal Research and Department of Gastroenterology and Hepatology, Amsterdam, The Netherlands.
S
S
Meisner
Academic Medical Center, Tygat Institute for Liver and Intestinal Research and Department of Gastroenterology and Hepatology, Amsterdam, The Netherlands.
Y H
YH
Shen
USC/Norris Comprehensive Cancer Center, Department of Biochemistry and Molecular Biology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA.
A S
AS
Lee
Research Centre for Infectious Diseases, Department of Molecular and Cellular Biology, School of Biological Sciences, University of Adelaide, South Australia, Australia.
J C
JC
Paton
Research Centre for Infectious Diseases, Department of Molecular and Cellular Biology, School of Biological Sciences, University of Adelaide, South Australia, Australia.
A W
AW
Paton
Academic Medical Center, Tygat Institute for Liver and Intestinal Research and Department of Gastroenterology and Hepatology, Amsterdam, The Netherlands.
V
V
Muncan
Academic Medical Center, Tygat Institute for Liver and Intestinal Research and Department of Gastroenterology and Hepatology, Amsterdam, The Netherlands.
G R
GR
van den Brink
Academic Medical Center, Tygat Institute for Liver and Intestinal Research and Department of Gastroenterology and Hepatology, Amsterdam, The Netherlands.|Academic Medical Center, Department of Internal Medicine, Amsterdam, The Netherlands.
J
J
Heijmans
D025601:Adenomatous Polyposis Coli Protein / Q000235:genetics*; D000818:Animals; D002454:Cell Differentiation; D049109:Cell Proliferation; D003110:Colonic Neoplasms / Q000235:genetics*; D000091342:Endoplasmic Reticulum Chaperone BiP; D059865:Endoplasmic Reticulum Stress; D004847:Epithelial Cells / Q000166:cytology* / Q000378:metabolism; D017353:Gene Deletion; D015972:Gene Expression Regulation, Neoplastic; D006360:Heat-Shock Proteins / Q000235:genetics*; D006801:Humans; D051379:Mice; D008822:Mice, Transgenic; D009154:Mutation; D013234:Stem Cells / Q000166:cytology* / Q000378:metabolism; D060449:Wnt Signaling Pathway; D051176:beta Catenin / Q000378:metabolism
D025601:Adenomatous Polyposis Coli Protein; D000091342:Endoplasmic Reticulum Chaperone BiP; C000717247:HSPA5 protein, human; D006360:Heat-Shock Proteins; C000717248:Hspa5 protein, mouse; C000613192:adenomatous polyposis coli protein, mouse; D051176:beta Catenin