Intestinal epithelial cell-specific CD98 expression regulates tumorigenesis in Apc(Min/+) mice.
The transmembrane glycoprotein CD98 regulates integrin signaling that in turn controls cell proliferation and survival. CD98 expression is upregulated in various carcinomas, including colorectal cancer. Recently, by generating gain- and loss-of-function mouse models featuring genetic manipulation of CD98 expression specifically in intestinal epithelial cells (IECs), we have explored the crucial role of CD98 in the regulation of intestinal homeostasis and inflammation-associated tumorigenesis. In the present study, we investigated the contribution of CD98 to intestinal tumorigenesis in Apc(Min/+) mice and the underlying mechanism of action. Mice featuring IEC-specific CD98 overexpression (Tg animals) were crossed with Apc(Min/+) mice, and the characteristics of intestinal adenoma formation were assessed. Compared with Apc(Min/+) mice, Tg/Apc(Min/+) animals exhibited increases in both intestinal tumor incidence and tumor size; these parameters correlated with enhanced proliferation and decreased apoptosis of IECs. IEC-specific CD98 overexpression resulted in increased synthesis of the oncogenic proteins c-myc and cyclin-D1 in Apc(Min/+) mice, independently of the Wnt-APC-β-catenin pathway, suggesting the implication of CD98 overexpression-mediated Erk activation. IEC-specific CD98 overexpression enhanced the production of proinflammatory cytokines and chemokines that are crucial for tumorigenesis. We validated our results in mice exhibiting IEC-specific CD98 downregulation (CD98(flox/+)VillinCre animals). IEC-specific CD98 downregulation efficiently attenuated tumor incidence and growth in Apc(Min/+) mice. The reduction of intestinal tumorigenesis upon IEC-specific CD98 downregulation was caused by the attenuation of IEC proliferation and cytokine/chemokine production. In conclusion, we show that CD98 exerts an oncogenic activity in terms of intestinal tumorigenesis, via an ability to regulate tumor growth and survival.
Department of Biology, Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, GA, USA. hang.nguyen@u-clermont1.fr
Hang Thi Thu
HT
Nguyen
Guillaume
G
Dalmasso
Yutao
Y
Yan
Hamed
H
Laroui
Moiz
M
Charania
Sarah
S
Ingersoll
Saravanan
S
Ayyadurai
Yuchen
Y
Zhang
Shanthi
S
Sitaraman
Didier
D
Merlin
D000236:Adenoma / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D025601:Adenomatous Polyposis Coli Protein / Q000235:genetics*; D000818:Animals; D017209:Apoptosis / Q000502:physiology; D049109:Cell Proliferation; D002471:Cell Transformation, Neoplastic / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D016207:Cytokines / Q000378:metabolism; D004847:Epithelial Cells / Q000378:metabolism*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005260:Female; D027261:Fusion Regulatory Protein-1 / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D006651:Histocytochemistry; D007413:Intestinal Mucosa / Q000378:metabolism* / Q000473:pathology; D007414:Intestinal Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D020935:MAP Kinase Signaling System; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism
D025601:Adenomatous Polyposis Coli Protein; D016207:Cytokines; D027261:Fusion Regulatory Protein-1; D048049:Extracellular Signal-Regulated MAP Kinases; D020929:Mitogen-Activated Protein Kinase Kinases