PLATELET-DERIVED GROWTH-FACTOR ISOFORMS PREVENT CELL-DEATH DURING STARVATION OF AKR-2B FIBROBLASTS

Confluent AKR-2B fibroblasts rapidly desintegrate upon removal of seru m until a final density of similar to 50% of the initial value was rea ched after 12 h. This density remained unchanged for at least 48 h. Pl atelet-derived growth factor (PDGF)-BB stimulated more than 95% of the se cells to divide. PDGF-AB or -BB added immediately after serum remov al caused complete survival of the cells, but did not stimulate cell d ivision as demonstrated by two-dimensional DNA flow cytometry. PDGF-AA was less effective leading to similar to 75% of the initial cell dens ity. This effect could be augmented by the addition of ocadaic acid, a potent phosphatase inhibitor, suggesting that protein phosphorylation plays a role in this process. By using tyrphostin AG807 it was demons trated that the signaling mechanism for survival requires receptor tyr osine autophosphorylation. (C) 1994 Wiley-Liss, Inc.