TUMOR NECROSIS FACTOR-ALPHA-DEPENDENT REGULATION OF PROSTAGLANDIN ENDOPEROXIDE SYNTHASE-2

Tumour necrosis factor alpha (TNF-alpha)-mediated regulation of prosta glandin endoperoxide synthase-2 (PGHS-2) mRNA levels was examined in m urine fibrosarcoma MCA-101 cells. We demonstrated that the formation o f prostaglandin E-2 (PGE(2)) is highly dependent on the expression of PGHS-2, enzyme in these cells. TNF-alpha-induced PGE(2) production,vas evident after 12 h and was associated with a significant TNF-alpha-me diated increase in PGHS-2 immunoreactive protein. A specific PGHS-2 in hibitor, NS-398, completely abolished the TNF-alpha-mediated increase in PGE(2) production, suggesting that the PGE(2) formed in response to TNF-alpha was derived from PGHS-2, TNF-alpha-mediated PGHS-2 mRNA acc umulation was observed at 1 h, remained elevated for 24 h, and was blo cked by actinomycin D, indicating that TNF-alpha increases PGHS-2 gene transcription. A significant post-transcriptional mechanism also cont ributed to the increased PGHS-2 mRNA accumulation as the mRNA half-lif e was approximately 4-5 h in TNF-alpha-stimulated cells, Inhibition of protein tyrosine phosphatases (PTPs) and protein tyrosine kinases (PT Ks) inhibited the TNF-alpha-mediated increase in PGHS-2 mRNA levels. W e suggest that PTPs and PTKs play a role in the transcriptional and/or post-transcriptional mechanisms that contribute to the regulation of the PGHS-2 gene by TNF-alpha. (C) 1998 Academic Press Limited.