EFFECT OF GROWTH-FACTORS ON GROWTH OF BOVINE PARATHYROID CELLS IN SERUM-FREE MEDIUM

Published work has suggested a possible role of the epidermal growth f actor receptor (EGFr) in parathyroid disease. Bovine parathyroid cells (BPCs) are frequently used as a tissue model for studying parathyroid disorders. We have studied the effect of the EGFr ligands EGF and tra nsforming growth factor alpha (TGF alpha), alone and with insulin-like growth factors IGF-I and IGF-II on BPC growth. Experiments were run i n triplicate and repeated three times. Cell numbers were assessed on d ay 5 by colorimetric MTT assay as well as by tritiated thymidine uptak e. Results show that TGF alpha alone (p < 0.05) and IGF-I and IGF-II a lone (p < 0.05) significantly stimulated growth over controls (t-test) . Furthermore, the combination of TGF alpha with IGF-I and IGF-II exhi bited significant enhancement above that seen with IGF-I and IGF-II al one (p < 0.01). EGF did not stimulate growth over controls. EGFr may b e expressed in BPCs, but TGF alpha exhibits a more potent growth stimu lus than EGF. Addition of IGF-I or IGF-II to the growth medium further enhances this effect.