RIP140 increases APC expression and controls intestinal homeostasis and tumorigenesis
Marion Lapierre, … , Malcolm Parker, Vincent Cavailles
Marion Lapierre, … , Malcolm Parker, Vincent Cavailles
Published March 25, 2014
Citation Information: J Clin Invest. 2014;124(5):1899-1913. https://doi.org/10.1172/JCI65178.
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Research Article Oncology

RIP140 increases APC expression and controls intestinal homeostasis and tumorigenesis

Abstract

Deregulation of the Wnt/APC/β-catenin signaling pathway is an important consequence of tumor suppressor APC dysfunction. Genetic and molecular data have established that disruption of this pathway contributes to the development of colorectal cancer. Here, we demonstrate that the transcriptional coregulator RIP140 regulates intestinal homeostasis and tumorigenesis. Using Rip140-null mice and mice overexpressing human RIP140, we found that RIP140 inhibited intestinal epithelial cell proliferation and apoptosis. Interestingly, following whole-body irradiation, mice lacking RIP140 exhibited improved regenerative capacity in the intestine, while mice overexpressing RIP140 displayed reduced recovery. Enhanced RIP140 expression strongly repressed human colon cancer cell proliferation in vitro and after grafting onto nude mice. Moreover, in murine tissues and human cancer cells, RIP140 stimulated APC transcription and inhibited β-catenin activation and target gene expression. Finally, RIP140 mRNA and RIP140 protein levels were decreased in human colon cancers compared with those in normal mucosal tissue, and low levels of RIP140 expression in adenocarcinomas from patients correlated with poor prognosis. Together, these results support a tumor suppressor role for RIP140 in colon cancer.

Authors

Marion Lapierre, Sandrine Bonnet, Caroline Bascoul-Mollevi, Imade Ait-Arsa, Stéphan Jalaguier, Maguy Del Rio, Michela Plateroti, Paul Roepman, Marc Ychou, Julie Pannequin, Frédéric Hollande, Malcolm Parker, Vincent Cavailles

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Figure 6

Regulation of APC gene transcription by RIP140 in human colon cancer cells.

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Regulation of APC gene transcription by RIP140 in human colon cancer cel...
(A) Expression of members of the β-catenin degradation complex was measured by real-time qPCR. Values represent fold changes ± SD corrected by 28S mRNA and normalized to HCT-GFP cells; n = 6 independent experiments. (B) Same as in A for RKO-siCTL and RKO-siRIP cells. (C) Schematic drawing of the human APC gene promoter region showing experimentally characterized transcription factor–binding sites. HCT116 cells were transfected with two different APC gene promoter reporter vectors or with an SV40-based reporter vector with or without a RIP140 expression vector. Relative luciferase activity was expressed as the means ± SD; n = 3 independent experiments. (D) ChIP experiments were performed on the APC gene proximal promoter, on an upstream region (Control), or on the CCNE2 promoter after ChIP using an antibody against total histone H3, an antibody against RIP140, or an irrelevant antibody (IgG). (E) Expression of APC was measured by real-time qPCR after overexpression (APC) or silencing (siAPC) of the APC gene. Values represent fold changes ± SD corrected by 28S mRNA and normalized to control cells; n = 6 independent experiments. (F) ABC immunolabeling in HCT116 cells with overexpression (APC) or silencing (siAPC) of the APC gene (β-catenin in green and nuclear staining in blue). Quantifications represent the means ± SD; n = 3 independent experiments for each condition. Original magnification, ×63. (G) Same as in F, with or without RIP140 overexpression. In each condition, data are expressed relative to controls without overexpression of RIP140. Mann-Whitney U test. *P < 0.05; **P < 0.01; ***P < 0.001.