A novel activating function of c-Src and Stat3 on HGF transcription in mammary carcinoma cells.
In the normal breast, hepatocyte growth factor (HGF) is primarily expressed by stromal cells, and stimulates in a paracrine manner epithelial cells expressing the HGF receptor (Met). In invasive human breast carcinomas, HGF and Met are frequently overexpressed, possibly establishing an autocrine HGF/Met loop that promotes tumour cell invasion. However, the mechanisms leading to autocrine HGF expression in carcinoma cells are not known. We previously demonstrated a cooperative effect between c-Src and Stat3 in the activation of HGF transcription in mammary carcinoma cells. The present report defines a novel Stat3 consensus site at nt -95 in the HGF promoter that is highly conserved in human and mouse, and is required for c-Src and Stat3 to activate HGF transcription in breast epithelial cells. DNA-protein binding studies demonstrated high affinity binding of a Stat3-containing complex to the nt -95 site. Endogenous Stat3 binding to this region of the HGF promoter in carcinoma cells expressing HGF was demonstrated using a chromatin immunoprecipitation assay. In addition, coexpression of Stat3 and activated c-Src caused increased expression of endogenous HGF mRNA and protein and marked cell scattering in breast epithelial cells. Our results delineate a novel c-Src/Stat3-dependent mechanism that regulates HGF promoter activity, and is linked to transformation of mammary epithelial cells.
Wojcik
E J
EJ
Department of Pathology and Molecular Medicine, Division of Cancer Biology and Genetics, Queen's University Cancer Research Institute, Kingston, ON, Canada.
Sharifpoor
S
S
Miller
N A
NA
Wright
T G
TG
Watering
R
R
Tremblay
E A
EA
Swan
K
K
Mueller
C R
CR
Elliott
B E
BE
D000818:Animals; D047369:Chromatin Immunoprecipitation; D024202:Electrophoretic Mobility Shift Assay; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D005799:Genes, Dominant; D017228:Hepatocyte Growth Factor / Q000235:genetics* / Q000378:metabolism; D008156:Luciferases / Q000378:metabolism; D008325:Mammary Neoplasms, Experimental / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D051379:Mice; D009154:Mutation / Q000235:genetics; D016392:Proto-Oncogene Proteins pp60(c-src) / Q000502:physiology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D050796:STAT3 Transcription Factor / Q000502:physiology*; D014158:Transcription, Genetic; D015533:Transcriptional Activation
D012333:RNA, Messenger; D050796:STAT3 Transcription Factor; D017228:Hepatocyte Growth Factor; D008156:Luciferases; D016392:Proto-Oncogene Proteins pp60(c-src)