Central role of epidermal growth factor (EGF) receptor density in anchorage-independent growth of normal rat kidney cells.

Epidermal growth factor (EGF) receptor levels are known to play a central role in density dependent growth regulation of normal rat kidney (NRK) fibroblasts. Here we show that EGF receptor expression is strongly decreased when NRK cells are cultured under anchorage independent conditions, and that expression is returned to original levels upon cell readherence. Agents that stimulate anchorage independent growth (AIG) of NRK cells in the presence of EGF are shown to upregulate both EGF receptor promoter activity and (125)I-EGF binding capacity. These data show that two aspects of phenotypic transformation of NRK cells, namely density arrest and AIG, can both directly be correlated to EGF receptor levels.