Abstract
RUNX3 has been suggested to be a tumor suppressor of gastric cancer. The gastric mucosa of the Runx3-null mouse develops hyperplasia due to enhanced proliferation and suppressed apoptosis accompanied by a decreased sensitivity to transforming growth factor beta1 (TGF-beta1). It is known that TGF-beta1 induces cell growth arrest by activating CDKN1A (p21(WAF1)(/Cip1)), which encodes a cyclin-dependent kinase inhibitor, and this signaling cascade is considered to be a tumor suppressor pathway. However, the lineage-specific transcription factor that cooperates with SMADs to induce p21 expression is not known. Here we show that RUNX3 is required for the TGF-beta-dependent induction of p21 expression in stomach epithelial cells. Overexpression of RUNX3 potentiates TGF-beta-dependent endogenous p21 induction. In cooperation with SMADs, RUNX3 synergistically activates the p21 promoter. In contrast, RUNX3-R122C, a mutation identified in a gastric cancer patient, abolished the ability to activate the p21 promoter or cooperate with SMADs. Furthermore, areas in mouse and human gastric epithelium where RUNX3 is expressed coincided with those where p21 is expressed. Our results suggest that at least part of the tumor suppressor activity of RUNX3 is associated with its ability to induce p21 expression.
Publication types
-
Research Support, Non-U.S. Gov't
MeSH terms
-
Animals
-
Cell Cycle Proteins / genetics*
-
Core Binding Factor Alpha 3 Subunit
-
Cyclin-Dependent Kinase Inhibitor p21
-
DNA-Binding Proteins / analysis
-
DNA-Binding Proteins / genetics
-
DNA-Binding Proteins / metabolism*
-
Gastric Mucosa / chemistry
-
Gastric Mucosa / drug effects
-
Gastric Mucosa / growth & development*
-
Gene Expression / drug effects
-
Gene Expression Profiling
-
Gene Expression Regulation
-
Humans
-
Mice
-
Mutation
-
Promoter Regions, Genetic / drug effects
-
Smad Proteins
-
Stomach Neoplasms / genetics
-
Stomach Neoplasms / metabolism*
-
Trans-Activators / metabolism*
-
Transcription Factors / analysis
-
Transcription Factors / genetics
-
Transcription Factors / metabolism*
-
Transforming Growth Factor beta / metabolism
-
Transforming Growth Factor beta / pharmacology*
-
Transforming Growth Factor beta1
-
Tumor Suppressor Proteins / analysis
-
Tumor Suppressor Proteins / genetics
-
Tumor Suppressor Proteins / metabolism*
-
Up-Regulation
Substances
-
CDKN1A protein, human
-
Cdkn1a protein, mouse
-
Cell Cycle Proteins
-
Core Binding Factor Alpha 3 Subunit
-
Cyclin-Dependent Kinase Inhibitor p21
-
DNA-Binding Proteins
-
Runx3 protein, human
-
Runx3 protein, mouse
-
Smad Proteins
-
TGFB1 protein, human
-
Tgfb1 protein, mouse
-
Trans-Activators
-
Transcription Factors
-
Transforming Growth Factor beta
-
Transforming Growth Factor beta1
-
Tumor Suppressor Proteins