Urokinase plasminogen activator is necessary but not sufficient for prostate cancer cell invasion.

The expression and function of urokinase plasminogen activator (uPA), an extracellular protease, were examined in four established prostate cancer lines, and one uPA-transfected cell line. The cell lines exhibited variable efficiency in uPA transcription, translation and specific proteolytic activity. A statistically significant inhibition of Boyden chamber invasion by anti-uPA monoclonal antibodies was demonstrated in cell lines TSU-PR1 and PC3. This inhibition suggests a direct role for uPA in the invasion of prostate cancer. However, variable processing of uPA mRNA, protein and proteolytic activity make prediction of in vitro invasion of prostate cancer difficult. Stable transfection experiments suggest that the proteolytic cascade generated by a cell is multiform and solitary alterations in uPA may not modify the proteolytic capability for invasion.