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 growth factor-TGF[beta]1 on cellular structure, especially on cell junctions and cytoskeleton, the distribution of ZO1, E-cadherin and desmoplakin as well as the organization of actin and keratin filaments have been examined immunohistochemically. In EGF-treated cultures as well as in TGF[beta]1-treated cultures, the distribution of adhesion proteins looked similar. On the sites where cells made contacts, the presence of ZO1, E-cadherin and desmoplakin was revealed seen as a continuous line around cells. EGF as well as TGF[beta]1 treatment induced no difference in the presence and distribution of cytokeratin 20; this marker of terminal differentiation was limited to superficial urothelial cells only. Also, the distribution of actin filaments was not significantly altered by any of the growth factors used. This indicates that neither cell junctions nor cytoskeleton of urothelial cells were affected by exogenously added growth factors. This may result from the influence of stroma on the formation of urothelium during the first days of culture of urinary bladder expiants and the production of growth factors in the culture itself.