Binding and processing of epidermal growth factor in Panc-I human pancreatic carcinoma cells

The binding of 125I-labeled epidermal growth factor (EGF) was studied in Panc-I human pancreatic carcinoma cells. At 37 degrees C, binding was rapid and associated with marked endocytosis of the ligand. Bound EGF was sequentially converted to a number of more acidic species as follows: pI 4.55 to pI 4.2, to pI 4.35, to pI 4.0. EGF internalization and processing were blocked at 4 degrees C. EGF did not alter cell growth when Panc-I cells were incubated in the presence of 2 to 10% serum. In contrast, when the serum concentration was lowered to 0.1%, EGF significantly enhanced cell replication after 6 days of culture.