Converging signals synergistically activate the LAMC2 promoter and lead to accumulation of the laminin gamma 2 chain in human colon carcinoma cells

TY - JOUR

T1 - Converging signals synergistically activate the LAMC2 promoter and lead to accumulation of the laminin gamma 2 chain in human colon carcinoma cells

AU - Olsen, Jørgen

AU - Kirkeby, Lene T

AU - Brorsson, Marianne M

AU - Dabelsteen, Sally

AU - Troelsen, Jesper T

AU - Bordoy, Randi

AU - Fenger, Kirsten

AU - Larsson, Lars-Inge

AU - Simon-Assmann, Patricia

N1 - Keywords: Carcinoma; Colonic Neoplasms; DNA-Binding Proteins; Drug Synergism; Hepatocyte Growth Factor; Humans; Laminin; Promoter Regions, Genetic; Regulatory Sequences, Nucleic Acid; Response Elements; Signal Transduction; Smad3 Protein; Smad4 Protein; Trans-Activators; Transcription Factor AP-1; Transforming Growth Factor beta; Tumor Cells, Cultured

PY - 2003

Y1 - 2003

N2 - The trimeric extracellular matrix molecule laminin-5 and its constituent chains (alpha 3, beta 3, gamma 2) are normally not detectable intracellularly in intestinal epithelial cells but the laminin gamma 2 chain can be detected in cancer cells at the invasive front of a subset of colon carcinomas. These cells are subjected to cytokines such as transforming growth factor beta 1 (TGF-beta 1) and hepatocyte growth factor (HGF), produced by the tumour cells or by the surrounding stromal cells. The purpose of the present work was to investigate whether TGF-beta 1 and HGF, known to stimulate the LAMC2 gene encoding the laminin gamma 2 chain, might synergize to activate the LAMC2 promoter, and to identify the promoter elements involved. We find evidence for synergy between TGF-beta and HGF with respect to laminin gamma 2 chain expression and promoter activation and demonstrate that this requires the 5' activator protein-1 (AP-1) element of the promoter and an additional upstream element which is also responsive to co-expression of the Smad3 protein from the TGF-beta signalling pathway. The transcripts encoding the other laminin-5 chains are not synergistically activated by HGF and TGF-beta. Thus the synergistic activation of the LAMC2 gene is mediated via different cis-elements and results in an overproduction of the laminin gamma 2 chain relative to the other laminin-5 constituent chains. This difference may explain why laminin gamma 2 chains accumulate in the cells at the invasive front of colon carcinomas.

AB - The trimeric extracellular matrix molecule laminin-5 and its constituent chains (alpha 3, beta 3, gamma 2) are normally not detectable intracellularly in intestinal epithelial cells but the laminin gamma 2 chain can be detected in cancer cells at the invasive front of a subset of colon carcinomas. These cells are subjected to cytokines such as transforming growth factor beta 1 (TGF-beta 1) and hepatocyte growth factor (HGF), produced by the tumour cells or by the surrounding stromal cells. The purpose of the present work was to investigate whether TGF-beta 1 and HGF, known to stimulate the LAMC2 gene encoding the laminin gamma 2 chain, might synergize to activate the LAMC2 promoter, and to identify the promoter elements involved. We find evidence for synergy between TGF-beta and HGF with respect to laminin gamma 2 chain expression and promoter activation and demonstrate that this requires the 5' activator protein-1 (AP-1) element of the promoter and an additional upstream element which is also responsive to co-expression of the Smad3 protein from the TGF-beta signalling pathway. The transcripts encoding the other laminin-5 chains are not synergistically activated by HGF and TGF-beta. Thus the synergistic activation of the LAMC2 gene is mediated via different cis-elements and results in an overproduction of the laminin gamma 2 chain relative to the other laminin-5 constituent chains. This difference may explain why laminin gamma 2 chains accumulate in the cells at the invasive front of colon carcinomas.

U2 - 10.1042/BJ20021454

DO - 10.1042/BJ20021454

M3 - Journal article

C2 - 12519076

SN - 0264-6021

VL - 371

SP - 211

EP - 221

JO - Biochemical Journal

JF - Biochemical Journal

IS - Pt 1

ER -