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Epithelial to mesenchymal transition is impaired in colon cancer cells with microsatellite instability.

ABSTRACT: Colorectal cancers (CRCs) displaying DNA microsatellite instability (MSI) are associated with a favorable natural history, but the molecular basis for this observation has not been defined. We sought to determine whether the epithelial to mesenchymal transition (EMT) is impaired in MSI-positive CRCs that characteristically have a mutant transforming growth factor-beta receptor type II (TGFBR2) gene.The induction of EMT by transforming growth factor-beta1 (TGF-beta1) was analyzed by phase contrast microscopy, immunofluorescence, quantitative reverse transcription polymerase chain reaction, immunoblotting, and cellular migration, and invasion assays. Expression of EMT markers was evaluated by immunohistochemistry and quantitative reverse transcription polymerase chain reaction in a series of human colorectal tumors.TGF-beta1 induced changes in cellular morphology, gene expression, motility, and invasion consistent with EMT in microsatellite stable (MSS) colon cancer cells, whereas cells with MSI and mutant TGFBR2 were unresponsive to TGF-beta1. These effects did not require Smad4, but depended on the recruitment of extracellular signal-regulated kinase. Tumor cells with MSI but wild-type TGFBR2 underwent EMT in response to TGF-beta1, indicating that TGFBR2 genotype is a key determinant of the EMT response in tumors with MSI. In human colorectal tumors, expression of EMT markers was significantly associated with adverse clinicopathologic features and the absence of MSI.These findings define a unique genotype-phenotype relationship between TGFBR2 and EMT that may contribute to the improved prognosis consistently observed in colon cancers with MSI.

SUBMITTER: Pino MS

PROVIDER: S-EPMC2846966 | biostudies-literature | 2010 Apr

REPOSITORIES: biostudies-literature

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Epithelial to mesenchymal transition is impaired in colon cancer cells with microsatellite instability.

Pino Maria S MS Kikuchi Hirotoshi H Zeng Min M Herraiz Maria-Teresa MT Sperduti Isabella I Berger David D Park Do-Youn DY Iafrate A John AJ Zukerberg Lawrence R LR Chung Daniel C DC

Gastroenterology 20091221 4

<h4>Background & aims</h4>Colorectal cancers (CRCs) displaying DNA microsatellite instability (MSI) are associated with a favorable natural history, but the molecular basis for this observation has not been defined. We sought to determine whether the epithelial to mesenchymal transition (EMT) is impaired in MSI-positive CRCs that characteristically have a mutant transforming growth factor-beta receptor type II (TGFBR2) gene.<h4>Methods</h4>The induction of EMT by transforming growth factor-beta1 ...[more]

PMID: 20026115

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Project description:Aberrant T-cell factor (TCF) transcription is implicated in the majority of colorectal cancers (CRCs). TCF transcription induces epithelial-mesenchymal transition (EMT), promoting a tumor-initiating cell (TIC) phenotype characterized by increased proliferation, multidrug resistance (MDR), invasion and metastasis. The data presented herein characterize topoisomerase IIα (TopoIIα) as a required component of TCF transcription promoting EMT. Using chromatin immunoprecipitation (ChIP) and protein co-immunoprecipitation (co-IP) studies, we show that TopoIIα forms protein-protein interactions with β-catentin and TCF4 and interacts with Wnt response elements (WREs) and promoters of direct target genes of TCF transcription, including: MYC, vimentin, AXIN2 and LEF1. Moreover, both TopoIIα and TCF4 ChIP with the N-cadherin promoter, which is a new discovery indicating that TCF transcription may directly regulate N-cadherin expression. TopoIIα N-terminal ATP-competitive inhibitors, exemplified by the marine alkaloid neoamphimedine (neo), block TCF activity in vitro and in vivo. Neo effectively inhibits TopoIIα and TCF4 from binding WREs/promoter sites, whereas protein-protein interactions remain intact. Neo inhibition of TopoIIα-dependent TCF transcription also correlates with significant antitumor effects in vitro and in vivo, including the reversion of EMT, the loss of TIC-mediated clonogenic colony formation, and the loss of cell motility and invasion. Interestingly, non-ATP-competitive inhibitors of TopoIIα, etoposide and merbarone, were ineffective at preventing TopoIIα-dependent TCF transcription. Thus, we propose that TopoIIα participation in TCF transcription may convey a mechanism of MDR to conventional TopoIIα inhibitors. However, our results indicate that TopoIIα N-terminal ATP-binding sites remain conserved and available for drug targeting. This article defines a new strategy for targeted inhibition of TCF transcription that may lead to effective therapies for the treatment of CRC and potentially other Wnt-dependent cancers.

Dataset Information

Epithelial to mesenchymal transition is impaired in colon cancer cells with microsatellite instability.

Publications

Epithelial to mesenchymal transition is impaired in colon cancer cells with microsatellite instability.

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