FAK-independent regulation of prolidase activity and collagen biosynthesis in MCF-7 cells

Prolidase E.C. 3.4.13.9] plays an important role in the recycling of proline for collagen synthesis and cell growth and this enzyme activity determines the rate of collagen turnover. It has been previously suggested that prolidase activity is regulated through signal mediated by the interaction of ECM proteins, with b1 integrin receptor and that this interaction is disturbed in MCF-7 cells. The potential candidates for mediating signal transduction are the nonreceptor tyrosine kinase p125FAK and two mitogen-activated protein (MAP) kinases, ERK-1 and ERK-2, which are activated upon attachment of cells to ECM. We found that serum starvation of MCF-7 cells for 24 hours contributed to a significant decrease (by about 30%) in prolidase activity and collagen biosynthesis. These phenomena were accompanied by suppression of MAP kinases expression without any effect on the expression of FAK. The data suggest that prolidase activity and collagen biosynthesis respond to signal mediated by MAP kinases, independently of FAK expression in MCF-7 cells.