The effects of growth factors on proliferation, survival and motility in a human embryonal carcinoma derived cell line

The balance between different cell populations in the developing organism is controlled by regulating the rates of multiplication, differentiation or death of their constituent cells. In the absence of a human embryonic stem cell that can be studied in vitro, the embryonal carcinoma derived cell line Tera-2 has for long been considered the second best alternative for studies in vitro. This cell line is multipotent in vivo and can be induced to undergo differentiation in vitro by addition ofretinoic acid.In this thesis, it is reported that differentiation has a marked effect on the expression of one growth factor gene in vitro. K-FGF mRNA was rapidly downregulated by addition of retinoic acid. However, when cells were cultured in RA for an extended period oftime (> 15 days) the K-FGF transcript reappeared.When Tera-2 cells were grown in serum-free medium, the increase in total cell number was stimulated by the addition of 1-10 ng/ml medium of aFGF or bFGF. The FGF effect was specific and could be abrogated by protamine sulphate. At least two classes of FGF receptors were found to bind to FGF in Tera-2 cells. By a combination of cell counts, autoradiography and immunohistochemistry it was possible to conclude that Tera-2 cells, grown in serum-free medium undergo apoptosis.The stimulatory effects of aFGF and bFGF on cell numbers could be concluded to be the result of the growth factor abrogating the apoptotic process. By adding the Insulin-like growth factor I or II to Tera-2 cells in serum-free medium an even greater survival effect was observed..Basic FGF at high concentrations exerted only a marginal effect on cell proliferation, but rather had a preferential effect on cell locomotion, supporting the concept that one growth factor can give rise to different biological effects at different concentrations.