Keratinocyte growth factor enhances urokinase-type plasminogen activator activity in HPV16 DNA-immortalized human...

We recently demonstrated that keratinocyte growth factor (KGF), a fibroblast-derived growth factor, induced anchorage-independent growth of HPV16 DNA-immortalized human uterine exocervical epithelial cells (HCE16/3 cell line) in soft agarose assay. We have now studied whether KGF might also regulate the plasminogen activator (PA) system, another transformation parameter related to cell invasiveness. HCE16/3 cells were found to produce urokinase-type PA (uPA) and small amounts of tissue-type PA (tPA) as determined by immunocapture assay. Secretion of both uPA and tPA was increased when HCE16/3 cells were exposed to KGF for 4 h and continued to increase during the next 24 h. The early increase following KGF treatment was presumably mediated by binding of KGF to its receptors. Enhanced secretion of uPA in HCE16/3 cells by KGF was also seen by zymographic analysis and immunofluorescence. According to Northern blotting KGF upregulated the transcription of uPA gene in HCE16/3 cells; the upregulation occurred only after 12 h of KGF treatment, suggesting that stimulation of uPA production by KGF is a biphasic event. As proteolysis is a prerequisite for tumor cell invasion, taken together with our previous results, the present findings suggest that KGF may play an important role in the transition of immortalized uterine cervical epithelial cells from in situ to invasive carcinoma.