Brcmocriptine Inhibits Colony Formation by Rat Pituitary Tumor Cells in a Double-Layered Agar Clonogenic Assay.

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 less than 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.