Effects of epidermal growth factor on collagen synthesis by an epithelioid cell line derived from normal rat kidney

Studies were performed to characterize the effects of both acute and chronic exposure to epidermal growth factor (EGF) on collagen biosynthesis by NRK52E cells, an epithelioid line established from normal rat kidney. Both conditions of exposure to EGF stimulated cell growth. Qualitative analysis revealed that NRK52E cells continued to synthesize types I, III, IV, and V collagens under all circumstances. However, both acute and chronic exposure to EGF increased two- to fourfold the amounts of collagenous proteins secreted by NRK52E cells, but decreased by 40 to 80% the amounts of collagenous material derived from the cell layers. Quantitative evaluation of type I and type III molecules confirmed that both conditions of exposure to EGF resulted in substantial increases in the amounts of these types of collagen secreted by the cells. However, analysis of the cell-associated types I and III molecules revealed that, while prolonged exposure to EGF significantly decreased the production of both types of collagen, acute exposure minimally affected type I collagen levels, but decreased type III production greater than 40%. Thus, conditions of acute exposure resulted in a slight increase in the total amount of type I collagen produced, but a slight decrease in the amount of type III collagen synthesized. In contrast, chronic exposure to EGF decreased the total amount of both collagen types synthesized, with type III being decreased to a greater extent (approximately 70%) than was type I (approximately 50%). Thus, the ratio of type III to type I collagen produced by NRK52E cells was decreased under both conditions of exposure to EGF. Therefore, these studies establish that EGF can modify matrix production in an epithelioid line of renal origin.