Effects of Epidermal growth factor (EGF) on the suppression of GH3 cell growth / 대한해부학회지

ABSTRACT

Some of the pituitary prolactinomas were reported that they don't have active dopamine receptors and do not respond to bromocriptine which is a dopamine agonist. GH3 cell line which is derived from the rat pituitary tumor cells lacks affinity of dopamine receptors and secrete prolactin as well as small amount of growth hormone. Although it has been reported that epidermal growth factor (EGF) induces functional expression of dopamine receptors on GH3 cells in vitro, there has been a contradictory result. In the present study, EGF effect on the GH3 cell response to the bromocriptine was observed in order to investigate whether EGF induces dopamine receptor expression on dopamine resistant tumors in the absence of serum. GH3 cells were cultured for 4 days in the serum-supplemented medium (SSM) followed by culture in serum-free medium (SFM) with or without EGF. Additionally, effect of tamoxifen was also observed. EGF decreased the cell number and the ratio of cell division of GH3 cells while the ratio of prolactin-immunoreac-tive cells was increased. However, EGF did not show any significant effect on the GH3 cell response to bromocriptine treatment. Although tamoxifen decreased the GH3 cell number by increasing apoptosis, it did not influence GH3 cell response to bromocriptine. Our results indicate that EGF does not increase the affinity of dopamine receptors on GH3 cells and is not useful for the treatment of the dopamine-resistant prolactinoma.