Anti-angiogenic activity of naturally occurring lower size isoforms of Buffalo pituitary prolactin

The lower size (14 kDa-18 kDa) isoforms of buffalo pituitary prolactin (PRL), separated from the monomer and higher size forms, has anti-angiogenic activity in human endothelial cell migration assay and chick embryo chorioallantoic membrane (CAM) analysis. The isoforms also showed 35 times less immunoreactivity than the hormone monomer. There was no 16 kDa isoform of buffalo PRL. This is the first demonstration that the PRL fragments, which are physiologically cleaved in pituitary glands and biochemically purified, inhibit angiogenesis.