Abstract
In order to assess the possible antiproliferative action of bromocriptine on pituitary tumors, the effects of the drug on colony formation were studied using GH3 cells grown in double-layered agar. Bromocriptine (300 nM) clearly inhibited both the number of colonies arising from single tumor cells as well as the size of the tumor cell colonies (p<0.001). The drug did not inhibit colony formation by cells derived from 2 non-pituitary tumors. The data show that this dopamine agonist blocks proliferation of rat pituitary tumor cells in vitro and lend further support to the preliminary clinical observations of an anti-tumor effect of bromocriptine in man.