Reconstituted basement membrane reduces proliferation and increases prolactin expression of GH(3) cells

This study investigated the effects of reconstituted basement membrane Matr igel on the proliferation and prolactin expression of GH(3) cells in cultur e for 6 days. When cells were cultured on Matrigel, the initial attachment was increased but the cell number was not changed with time whereas rapid i ncrease in cell number was observed in cultures on plastic. Bromodeoxyuridi ne (BrdU)-labeling showed that BrdU incorporation ratio of GH, cells cultur ed on Matrigel was about one half of that observed with cells cultured on p lastic (9.7+/-0.7% vs. 18.7+/-1.2%). Immunocytochemistry revealed that the ratio of the prolactin-immunoreactive GH(3) cells was about 3.6 times (58.4 +/-2.9% on Matrigel vs. 16.2+/-1.4% on plastic), which was compatible with the results of Western blot analysis. In situ hybridization demonstrated th at prolactin mRNA-positive cells were identified more frequently when cells were cultured on Matrigel compared to cultures on plastic. These findings indicate that Matrigel is a proper culture substrate for the long-term cult ure of GH(3) pituitary cells due to the inhibition of overgrowth and promot ion of prolactin expression.