Glycyl-L-histidyl-L-lysine, a growth promoting factor for human cells

The growth promoting activity of a synthesis tripeptide, glycyl-L-histidyl-L-lysine (GHL) as a possible serum substitute was determined using human KB cells. GHL was found to stimulate the growth of human KB, and HeLa cells, but not WI-38 cells when employed in serum limited medium containing bovine serum albumin (BSA). The rate of growth of cells in this medium was similar to that of cells grown in medium containing 5% serum. While BSA did enhance slightly the growth of cells, its major function appeared to be in maintaining cellular viability. The growth promoting activity was specific for GHL; other synthetic peptides which were similar in composition had no activity, but they did interfere with the growth promoting activity of GHL. These observations suggest that by modifying GHL, analogues could be developed which might regulate cell growth and be useful in cancer chemotherapy.