Loss of prostasin (PRSS8) in human bladder transitional cell carcinoma cell lines is associated with epithelial-mesenchymal transition (EMT).
BACKGROUND
The glycosylphosphatidylinositol (GPI)-anchored epithelial extracellular membrane serine protease prostasin (PRSS8) is expressed abundantly in normal epithelia and essential for terminal epithelial differentiation, but down-regulated in human prostate, breast, and gastric cancers and invasive cancer cell lines. Prostasin is involved in the extracellular proteolytic modulation of the epidermal growth factor receptor (EGFR) and is an invasion suppressor. The aim of this study was to evaluate prostasin expression states in the transitional cell carcinomas (TCC) of the human bladder and in human TCC cell lines.


METHODS
Normal human bladder tissues and TCC on a bladder cancer tissue microarray (TMA) were evaluated for prostasin expression by means of immunohistochemistry. A panel of 16 urothelial and TCC cell lines were evaluated for prostasin and E-cadherin expression by western blot and quantitative PCR, and for prostasin gene promoter region CpG methylation by methylation-specific PCR (MSP).


RESULTS
Prostasin is expressed in the normal human urothelium and in a normal human urothelial cell line, but is significantly down-regulated in high-grade TCC and lost in 9 (of 15) TCC cell lines. Loss of prostasin expression in the TCC cell lines correlated with loss of or reduced E-cadherin expression, loss of epithelial morphology, and promoter DNA hypermethylation. Prostasin expression could be reactivated by demethylation or inhibition of histone deacetylase. Re-expression of prostasin or a serine protease-inactive variant resulted in transcriptional up-regulation of E-cadherin.


CONCLUSIONS
Loss of prostasin expression in bladder transitional cell carcinomas is associated with epithelial-mesenchymal transition (EMT), and may have functional implications in tumor invasion and resistance to chemotherapy.
Department of Molecular Biology, Burnett School of Biomedical Sciences, University of Central Florida College of Medicine, Orlando, Florida 32816, USA. lchen@mail.ucf.edu
Li-Mei
LM
Chen
Nicole J
NJ
Verity
Karl X
KX
Chai
D015820:Cadherins / Q000235:genetics / Q000378:metabolism; D002295:Carcinoma, Transitional Cell / Q000201:enzymology* / Q000235:genetics / Q000503:physiopathology; D002454:Cell Differentiation; D002460:Cell Line; D019175:DNA Methylation; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D012697:Serine Endopeptidases / Q000235:genetics / Q000378:metabolism*; D001743:Urinary Bladder / Q000166:cytology / Q000378:metabolism; D001749:Urinary Bladder Neoplasms / Q000201:enzymology* / Q000235:genetics / Q000503:physiopathology; D019459:Urothelium / Q000166:cytology* / Q000378:metabolism; D000099271:Prostasin
D015820:Cadherins; D012697:Serine Endopeptidases; D000099271:Prostasin