title: Effect of growth factors and lactogenic hormones on expression of plasminogen activator-related genes and cell proliferation in a bovine mammary epithelial cell line.
abstract: There is conflicting evidence in the literature as to whether up-regulation of urokinase plasminogen activator (u-PA) expression is related to bovine mammary epithelial cell growth. The role of u-PA receptor (u-PAR) and that of the plasminogen activator inhibitors type 1 and type 2 (PAI-1 and PAI-2) in bovine mammary epithelial cell proliferation is not known. The effect of growth factors and various hormones known to affect mammary function on expression of u-PA, u-PAR, PAI-1, PAI-2 and cell proliferation using the BME-UV1 bovine mammary epithelial cell line was examined. Cell proliferation was measured using the MTT assay and direct cell enumeration. Results showed that both IGF-1 and EGF increased cell proliferation but EGF was a more potent mitogen than IGF-1. Furthermore, IGF-1 increased by 2-fold expression of both u-PA and u-PAR while EGF increased by 3·8-fold the expression of only u-PAR. Both growth factors had no effect on expression of PAI-1 and PAI-2. In a manner consistent with changes in gene expression, EGF and to a lesser extent IGF-1 up-regulated total cell associated, membrane-bound and secreted u-PA activity. Thus, a strong correlation exists between u-PAR gene expression along with the activity of u-PA present on cell membranes and cell proliferation. Dexamethasone, prolactin and surprisingly insulin had no effect on cell proliferation. Dexamethasone alone and when combined with insulin or prolactin up-regulated gene expression of both PAI- and PAI-2 but not that of u-PA and u-PAR. Decreased total cell-associated, membrane-bound and secreted u-PA activity was detected in cells cultured in the presence of dexamethasone when combined with insulin or prolactin. However no such effect was observed in the presence of dexamethasone alone. Thus, dexamethasone acting synergistically with prolactin or insulin inhibits the activation of the plasmin-plasminogen system but this inhibition is not correlated with any changes in cell proliferation.
authors.affiliation: Department of Animal Science and Aquaculture, Agricultural University of Athens, 75 Iera Odos, 11855 Athens, Greece. gtheod@aua.gr
authors.forename: Georgios
authors.initials: G
authors.lastname: Theodorou
authors.forename: Chiara
authors.initials: C
authors.lastname: Pecorini
authors.forename: Raffaella
authors.initials: R
authors.lastname: Rebucci
authors.forename: Francesca
authors.initials: F
authors.lastname: Saccone
authors.forename: Christina
authors.initials: C
authors.lastname: Lecchi
authors.forename: Ioannis
authors.initials: I
authors.lastname: Politis
authors.forename: Antonella
authors.initials: A
authors.lastname: Baldi
mesh_terms: D000818:Animals; D002417:Cattle; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects*; D036341:Intercellular Signaling Peptides and Proteins / Q000494:pharmacology*; D008321:Mammary Glands, Animal / Q000166:cytology*; D010960:Plasminogen Activators / Q000235:genetics / Q000378:metabolism*; D011388:Prolactin / Q000494:pharmacology*
chemical_list: D036341:Intercellular Signaling Peptides and Proteins; D011388:Prolactin; D010960:Plasminogen Activators