Heparin‐binding epidermal growth factor‐like growth factor functionally antagonizes interstitial cystitis antiproliferative factor via mitogen‐activated protein kinase pathway activation

• Published in: BJU international Vol. 103; no. 4; pp. 541 - 546
• Main Authors: Kim, Jayoung, Keay, Susan K., Freeman, Michael R.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.02.2009; Wiley-Blackwell
• Subjects: APF; Biological and medical sciences; Blotting, Western; Cell Proliferation - drug effects; Cystitis, Interstitial - metabolism; Epithelial Cells - drug effects; Glycoproteins - antagonists & inhibitors; HB‐EGF; Heparin-binding EGF-like Growth Factor; Humans; Intercellular Signaling Peptides and Proteins - pharmacology; Intercellular Signaling Peptides and Proteins - secretion; interstitial cystitis; Medical sciences; mitogen activated protein kinase; Mitogen-Activated Protein Kinases - metabolism; Muscle Contraction - drug effects; Nephrology. Urinary tract diseases; Urinary Bladder - drug effects; Urinary system involvement in other diseases. Miscellaneous; Urinary tract. Prostate gland; Antineoplastic agent; Nephrology; Urinary system disease; Enzyme; HB-EGF; Transferases; Mitogen-activated protein kinase; mitogen activated protein kinase; Activation; Urinary tract disease; Urology; Heparin-binding epidermal growth factor-like growth factor; APF; Interstitial cystitis
• ISSN: 1464-4096; 1464-410X
• DOI: 10.1111/j.1464-410X.2008.08097.x

OBJECTIVE To delineate the mechanism underlying the potential functional relationship between interstitial cystitis antiproliferative factor (APF) and heparin‐binding epidermal growth factor‐like growth factor (HB‐EGF), as APF has previously been shown to decrease the proliferation rate of normal bladder epithelial cells and the amount of HB‐EGF produced by these cells. MATERIALS AND METHODS APF‐responsive T24 transitional carcinoma bladder cells were treated with high‐pressure liquid chromatography‐purified native APF with or without HB‐EGF to determine the involvement of signalling pathways and proliferation by Western blot analysis, p38 mitogen‐activated protein kinase (MAPK) and extracellular signal‐regulated kinase (Erk)/MAPK assays, and 3‐(4,5‐dimethylthiazolyl‐2)‐2,5‐diphenyltetrazolium bromide (MTT) assay. RESULTS Cyclic stretch induced the secretion of HB‐EGF from T24 cells overexpressing the HB‐EGF precursor, resulting in enhanced proliferation. T24 cells treated with APF had increased p38MAPK activity and suppressed cell growth, events that were both reversed by treatment with a p38MAPK‐selective inhibitor. Activation of Erk/MAPK by HB‐EGF was inhibited by APF, and APF did not stimulate p38MAPK in the presence of soluble HB‐EGF or when cells overexpressed constitutively secreted HB‐EGF. Lastly, APF inhibitory effects on cell growth were attenuated by HB‐EGF. CONCLUSIONS These results indicate that HB‐EGF and APF are functionally antagonistic and signal through parallel MAPK signalling pathways in bladder cells.