Exogenously added growth factors have no effect on formation of cell junctions and cytoskeleton in urothelial cells in culture

To elucidate the effects of epidermal growth factor-EGF and transforming gr owth factor-TGF beta 1 on cellular structure, especially on cell junctions and cytoskeleton, the distribution of ZO1, E-cadherin and desmoplakin as we ll as the organization of actin and keratin filaments have been examined im munohistochemically. In EGF-treated cultures as well as in TGF beta 1-treat ed cultures, the distribution of adhesion proteins looked similar. On the s ites where cells made contacts, the presence of ZO1, E-cadherin and desmopl akin was revealed seen as a continuous line around cells. EGF as well as TG F beta 1 treatment induced no difference in the presence and distribution o f cytokeratin 20; this marker of terminal differentiation was limited to su perficial urothelial cells only. Also, the distribution of actin filaments was not significantly altered by any of the growth factors used. This indic ates that neither cell junctions nor cytoskeleton of urothelial cells were affected by exogenously added growth factors. This may result from the infl uence of stroma on the formation of urothelium during the first days of cul ture of urinary bladder explants and the production of growth factors in th e culture itself.