TUMOR-NECROSIS-FACTOR-ALPHA INDUCES INTERLEUKIN-6 MESSENGER-RNA AND PROTEIN IN HUMAN GRANULOSA LUTEINIZING CELLS VIA PROTEIN-TYROSINE KINASE WITHOUT INVOLVING CERAMIDE

This study examines how interleukin-6 (IL-6) expression by human lutei nizing granulosa cells is regulated. IL-6 was assayed in culture super natants, mRNA in cells by in situ hybridization and by a competitive r everse-transcriptase polymerase chain reaction (RT-PCR). TNF alpha (10 0 pg(-1) ng/ml) induced IL-6 mRNA and protein. Phorbol 12-myristate 13 -acetate (PMA) (50 nM) mimicked this effect. DibutyrylcAMP (1 mM) and 10 mu M forskolin, C2-, C6- and C8-ceramide (15 mu M), all had no effe ct. The inhibitor of protein tyrosine kinase (PTK), genistein (100 mu g/ml) reduced tumor necrosis factor (TNF) effects. The inhibitors of p rotein kinase C (PKC) (staurosporine, 10 nM), of phospholipase C (U731 22, 2 mu M), of phospholipase A2 (PLA(2)), (indomethacin 30 mu M, mepa crin 50 mu M, nordihydroguaiaretic acid 10 mu M, ONO-RS-082 3,5 mu M), none prevented it. Hence, IL-6 is induced by TNF alpha via activation of PTK. Protein kinase A, phosphoinositide and conventional PKC, sphi ngomyelin and PLA(2) pathways are not implicated. (C) 1997 Elsevier Sc ience Ireland Ltd.