Diminished expression of CRHR2 in human colon cancer promotes tumor growth and EMT via persistent IL-6/Stat3 signaling.
OBJECTIVE
Chronic inflammation promotes development and progression of colorectal cancer (CRC). We explored the distribution of Corticotropin-Releasing-Hormone (CRH)-family of receptors and ligands in CRC and their contribution in tumor growth and oncogenic EMT.


METHODS
mRNA expression of CRH-family members was analyzed in CRC (N=56) and control (N=46) samples, 7 CRC cell lines and normal NCM460 cells. Immunohistochemical detection of CRHR2 was performed in 20 CRC and 5 normal tissues. Cell proliferation, migration and invasion were compared between Urocortin-2 (Ucn2)-stimulated parental and CRHR2-overexpressing (CRHR2+) cells in absence or presence of IL-6. CRHR2/Ucn2-targeted effects on tumor growth and EMT were validated in SW620-xenograft mouse models.


RESULTS
CRC tissues and cell lines showed decreased mRNA and protein CRHR2 expression compared to controls and NCM460, respectively. The opposite trend was shown for Ucn2. CRHR2/Ucn2 signaling inhibited cell proliferation, migration, invasion and colony formation in CRC-CRHR2+ cells.In vivo, SW620-CRHR2+ xenografts showed decreased growth, reduced expression of EMT-inducers and elevated levels of EMT-suppressors. IL-1b, IL-6 and IL-6R mRNAs where diminished in CRC-CRHR2+ cells, while CRHR2/Ucn2 signaling inhibited IL-6-mediated Stat3 activation, invasion, migration and expression of downstream targets acting as cell cycle- and EMT-inducers. Expression of cell cycle- and EMT-suppressors was augmented in IL-6/Ucn2-stimulated CRHR2+ cells. In patients, CRHR2 mRNA expression was inversely correlated with IL-6R and vimentin levels and metastasis occurrence, while positively associated with E-cadherin expression and overall survival.


CONCLUSIONS
CRHR2 downregulation in CRC supports tumor expansion and spread through maintaining persistent inflammation and constitutive Stat3 activation. CRHR2lowCRC phenotypes are associated with higher risk for distant metastases and poor clinical outcomes.
IBD Center, Division of Digestive Diseases, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.
Jorge A
JA
Rodriguez
Unidad de Investigacion en Enfermedades Oncologicas, Hospital Infantil de Mexico Federico Gomez, Mexico City, Mexico.
Sara
S
Huerta-Yepez
IBD Center, Division of Digestive Diseases, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.
Ivy Ka Man
IK
Law
Unidad de Investigacion en Enfermedades Oncologicas, Hospital Infantil de Mexico Federico Gomez, Mexico City, Mexico.
Guillermina J
GJ
Baay-Guzman
Unidad de Investigacion en Enfermedades Oncologicas, Hospital Infantil de Mexico Federico Gomez, Mexico City, Mexico.
Belen
B
Tirado-Rodriguez
IBD Center, Division of Digestive Diseases, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.
Jill M
JM
Hoffman
Center for Systems Biomedicine, Division of Digestive Diseases, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.
Dimitrios
D
Iliopoulos
IBD Center, Division of Digestive Diseases, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA ; Dept. of Gastroenterology and Hepatology, Leiden University Medical Center, Leiden, The Netherlands.
Daniel W
DW
Hommes
Dept. of Gastroenterology and Hepatology, Leiden University Medical Center, Leiden, The Netherlands.
Hein W
HW
Verspaget
Gail and Gerard Oppenheimer Family Center for Neurobiology of Stress, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.
Lin
L
Chang
IBD Center, Division of Digestive Diseases, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.
Charalabos
C
Pothoulakis
IBD Center, Division of Digestive Diseases, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA ; Unidad de Investigacion en Enfermedades Oncologicas, Hospital Infantil de Mexico Federico Gomez, Mexico City, Mexico ; Division of Surgery, School of Medicine, University of Crete, Heraklion, Crete, Greece.
Stavroula
S
Baritaki
colorectal cancer; inflammation; metastasis; neuropeptides