INTERLEUKIN-1-ALPHA INDUCES CORTICOTROPIN-RELEASING FACTOR SECRETION AND SYNTHESIS FROM NPLC-KC CELLS THROUGH VARIOUS 2ND-MESSENGER PATHWAYS

Interleukin-1 (IL1) is a key messenger implicated in endocrine and imm une systems that interact to mediate the stress response. Corticotropi n-releasing factor (CRF) secretion and synthesis in the NPLC-KC human hepatoma cell line has been shown to respond to IL1 stimulation. We ha ve studied how various inhibitors of second messenger pathways alter t his IL1 effect. NPLC-KC cells were grown in six-well Costar plates and treated for 12 or 24 h with or without 500 pM IL1 (alpha form) in the presence of various inhibitors of second messenger pathways. Inhibito rs included the protein kinase C (PKC) inhibitor, H-7; the protein kin ase A inhibitor, IP20; or the cyclooxygenase inhibitor indomethacin (I ND). Both cell extracts and secretion media were assayed for CRF-Like immunoreactivity by radioimmunoassay. IP20, H-7, and IND all reduced b asal CRF secretion at 24 h but not at 12 h. No effects were seen on ba sal CRF synthesis with these inhibitors. The three inhibitors also red uced IL1 effects on CRF secretion at 12 and 24 h. The reduction seen w ith all three inhibitors was statistically significant (P < 0.05) at 1 2 h. Although a reduction was seen with all three inhibitors at 24 h, a statistically significant reduction (P < 0.05) was demonstrable only for H-7. IL1 stimulated CRF synthesis in the NPLC-KC cells appears to only involve PKC pathways. Only the PKC inhibitor H-7 reduced the aug mentation that IL1 produces on CRF synthesis. This effect was statisti cally significant at 12 and 24 h (P < 0.05). (C) 1994 Wiley-Liss, Inc.