Glycosylation-dependent cell adhesion molecule 1 (GlyCAM 1) is induced by prolactin and suppressed by progesterone in mammary epithelium

Glycosylation-dependent cell adhesion molecule 1 (GlyCAM 1), a mucin-like e ndothelial glycoprotein, was induced by PRL and suppressed by progesterone in the mammary gland of mice, and in HC11 mouse mammary epithelial cells. C omplementary DNA microarray analysis revealed that expression of GlyCAM 1 w as reduced in the mammary gland of PRL-gene disrupted mice (PRL-/-) compare d with control (PRL+/-) littermates. This result was confirmed by in situ h ybridization and immunostaining. The messenger RNA (mRNA) encoding GIS CAM 1 was present in mammary epithelia of PRL-stimulated mice. Immunohistochemi stry indicated that GlyCAM 1 protein was detectable both in mammary epithel ia and in the ductal lumen in PRL+/- virgin mice, but not in PRL-/- mice. G lyCAM 1 mRNA was highly induced by grafting pituitary glands from normal li ttermates. Trace amounts of mRNA for GlyCAM 1 were detected by RT-PCR in ma mmary tissue of PRL-/- mice. Progesterone inhibited both basal and PRL-stim ulated GlyCAM 1 transcription. In HC11 cells, GlyCAM 1 mRNA was induced in cells treated with insulin, dexamethasone, and PRL. Similar to the in vivo studies. progesterone inhibited the induction of GlyCAM 1 transcription. In CHO cells, PRL stimulated transcription of a luciferase reporter gene cont aining an 800-bp promoter fragment of GlyCAM 1, and progesterone partially suppressed the PRL effect. These data demonstrate that expression of GlyCAM 1 in mammary gland is under the control of both PRL and progesterone.