Role of PPARgamma and EGFR signalling in the urothelial terminal differentiation programme.
Recently, considerable interest has focused on the ability of activated peroxisome proliferator-activated receptor gamma (PPARgamma) to promote cytodifferentiation in adipocytes and some carcinoma cells; however, the role of PPARgamma in normal epithelial cytodifferentiation is unknown. Using uroplakin (UP) gene expression as a specific correlate of terminal urothelial cytodifferentiation, we investigated the differentiation-inducing effects of PPARgamma activation in normal human urothelial (NHU) cells grown as finite cell lines in monoculture. Two high-affinity activators of PPARgamma, troglitazone (TZ) and rosiglitazone (RZ) induced the expression of mRNA for UPII and UPIb and, to a lesser extent, UPIa. The specificity of the effect was shown by pretreating cells with a PPARgamma antagonist, GW9662, which attenuated the TZ-induced response in a dose-specific manner. The PPARgamma-mediated effect on UP gene expression was maximal when there was concurrent inhibition of autocrine-activated epidermal growth factor receptor (EGFR) signalling through either the phosphatidylinositol 3-kinase or extracellular signal-regulated kinase (ERK) pathways. The use of a specific EGFR tyrosine kinase inhibitor, PD153035, correlated with PPARgamma dephosphorylation and translocation to the nucleus, indicating a mechanism for regulating the balance between proliferation and differentiation. This is the first identification of specific factors involved in regulating differentiation-associated gene changes in urothelium and the first unambiguous evidence of a role for PPARgamma signalling in the terminal differentiation programme of a normal epithelium.
Varley
Claire L
CL
Jack Birch Unit of Molecular Carcinogenesis, Department of Biology, University of York YO10 5YW, UK.
Stahlschmidt
Jens
J
Lee
Wen-Chun
WC
Holder
Julie
J
Diggle
Christine
C
Selby
Peter J
PJ
Trejdosiewicz
Ludwik K
LK
Southgate
Jennifer
J
D021581:Active Transport, Cell Nucleus; D017667:Adipocytes / Q000378:metabolism; D000813:Anilides / Q000494:pharmacology; D000818:Animals; D015153:Blotting, Western; D002417:Cattle; D002454:Cell Differentiation; D002460:Cell Line; D049109:Cell Proliferation; D002839:Chromans / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004815:Epidermal Growth Factor / Q000378:metabolism; D004848:Epithelium / Q000378:metabolism; D066246:ErbB Receptors / Q000378:metabolism*; D005786:Gene Expression Regulation; D006801:Humans; D047468:Immunoprecipitation; D008024:Ligands; D008562:Membrane Glycoproteins / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D008856:Microscopy, Fluorescence; D047495:PPAR gamma / Q000378:metabolism / Q000502:physiology*; D010766:Phosphorylation; D011401:Promoter Regions, Genetic; D011799:Quinazolines / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D012260:Ribonucleases / Q000378:metabolism; D015398:Signal Transduction; D045162:Thiazolidinediones / Q000378:metabolism; D013997:Time Factors; D000077288:Troglitazone; D060170:Uroplakin II; D060171:Uroplakin III; D060167:Uroplakin Ia; D060169:Uroplakin Ib; D019459:Urothelium / Q000166:cytology / Q000378:metabolism*
C457499:2-chloro-5-nitrobenzanilide; D000813:Anilides; D002839:Chromans; D004791:Enzyme Inhibitors; D008024:Ligands; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D047495:PPAR gamma; D011799:Quinazolines; D012333:RNA, Messenger; D045162:Thiazolidinediones; C086451:UPK1A protein, human; C086452:UPK1B protein, human; C554658:UPK2 protein, human; D060170:Uroplakin II; D060171:Uroplakin III; D060167:Uroplakin Ia; D060169:Uroplakin Ib; D004815:Epidermal Growth Factor; D066246:ErbB Receptors; D012260:Ribonucleases; D000077288:Troglitazone; C088860:4-((3-bromophenyl)amino)-6,7-dimethoxyquinazoline