Induction of apoptosis in luteinized granulosa cells by the MAP kinase kinase (MEK) inhibitor PD98059

Our objective is to test the hypothesis that inhibition of mitogen-activate d protein (MAP) kinase kinase (MEK) with PD98059 in human luteinized granul osa cells will block epidermal growth (EGF)-stimulated MAP kinase activity and induce apoptosis, Luteinized granulosa cells from human in vitro fertil ization aspirates were cultured and treated with the following: (1) vehicle ; (2) PD98059; (3) EGF; (4) PD98059 + EGF. Treatment with PD98059 suppresse d MAP kinase activity, inhibited MAP kinase phosphorylation by Western blot analysis, blocked nuclear translocation of phosphorylated MAP kinase by co nfocal microscopy, and increased percentages of subdiploid apoptotic nuclei by flow cytometry, Our data are the first evidence that a relationship may exist between the MAP kinase pathway and control of apoptosis in human lut einized granulosa cells. These results support the hypothesis that suppress ion of the MAP kinase pathway may lead to apoptosis in these cells. (C) 199 9 Academic Press.