Document Detail

Activated Ras protein accelerates cell cycle progression to perturb Madin-Darby canine kidney cystogenesis.
MedLine Citation:
PMID:  22829590     Owner:  NLM     Status:  MEDLINE    
In a number of human cancer cells, K-RAS is frequently mutated and activated constitutively, culminating in the induction of continuous cell growth, a hallmark of cancer cells. It is still unclear, however, how the mutated K-RAS induces morphological abnormalities in cancerous tissues. To investigate the mechanism underlying the K-RAS-induced morphological changes, we utilized an auxin-dependent protein expression system, which enabled us to rapidly induce and evaluate constitutively active K-Ras in MDCK (Madin-Darby canine kidney) cysts, a model for polarized epithelial structure. Cells carrying the constitutively active KRasV12 gene were morphologically indistinguishable from normal cells in two-dimensional culture. However, in a gel of extracellular matrix, KRasV12-expressing cells failed to form a spherical cyst. When KRasV12 induction was delayed until after cyst formation, some cells in the cyst wall lost polarity and were extruded into and accumulated in the luminal space. With effector-specific mutants of KRasV12 and inhibitors for MEK and PI3-kinase, we found that both the Raf-MEK-ERK and PI3-kinase axes are necessary and sufficient for this phenotype. Live cell imaging with cell cycle indicators showed that KRasV12 expression promoted cell cycle progression, which was prevented by either MEK or PI3-kinase inhibitors. From these results, we provide a model wherein active-Ras induces cell cycle progression leading to apical cell extrusion through Raf and PI3-kinase in a cooperative manner. The system developed here can be applied to drug screening for various cancers originating from epithelial cells.
Atsuro Sakurai; Michiyuki Matsuda; Etsuko Kiyokawa
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2012-07-24
Journal Detail:
Title:  The Journal of biological chemistry     Volume:  287     ISSN:  1083-351X     ISO Abbreviation:  J. Biol. Chem.     Publication Date:  2012 Sep 
Date Detail:
Created Date:  2012-09-17     Completed Date:  2012-12-04     Revised Date:  2013-09-17    
Medline Journal Info:
Nlm Unique ID:  2985121R     Medline TA:  J Biol Chem     Country:  United States    
Other Details:
Languages:  eng     Pagination:  31703-11     Citation Subset:  IM    
Laboratory of Bioimaging and Cell Signaling, Graduate School of Biostudies, Kyoto University, Yoshida Konoe-cho, Kyoto 606-8501, Japan.
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MeSH Terms
Carcinoma / metabolism*
Cell Proliferation
Cell Separation
Fluorescence Resonance Energy Transfer
Gene Expression Regulation, Neoplastic*
Kidney / metabolism*
Models, Genetic
Phosphatidylinositol 3-Kinases / metabolism*
raf Kinases / metabolism
ras Proteins / metabolism*
Reg. No./Substance:
EC 2.7.1.-/Phosphatidylinositol 3-Kinases; EC Kinases; EC Proteins

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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