Walenga RW, Kester M, Coroneos E, Butcher S, Dwivedi R, Statt C. Constitutive expression of prostaglandin endoperoxide G/H synthetase (PGHS)-2 but not PGHS-1 in hum an tracheal epithelial cells in vitro.
PROSTAGLANDINS 1996;
52:341-59. [PMID:
8948503 DOI:
10.1016/s0090-6980(96)00101-3]
[Citation(s) in RCA: 42] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Primary cultures of human tracheal epithelial (HTE) cells cultured in vitro, in defined serum-free media, express prostaglandin endoperoxide G/H synthase (PGHS) activity and produce prostaglandin E2 (PGE2). In contrast to every other cell type studied to date, HTE cells appear to constitutively express PGHS-2, the 'inducible' form of the enzyme, while expressing little or no PGHS-1, the 'housekeeping' isoenzyme in vitro. Prostaglandin synthesis in HTE cells was reduced by a selective PGHS-2 inhibitor, N-[2-cyclohexyloyl-4-nitrophenyl] methane-sulfonamide (NS398), with an IC50 of approximately 1 microM. Immunoblotting and immunoprecipitation of enzymatic activity with isozyme-specific antisera revealed only the PGHS-2 isoform. Full length human cDNA probes detected only PGHS-2 message in Northern blots. Neither PGHS-2 activity nor mRNA levels were dependent on, nor stimulated by peptide growth factors present in the defined serum-free growth medium, or by serum. Prolonged maintenance in the absence of retinoic acid, however, lead to a decline in PGHS activity. Phorbol-myristate acetate (PMA) induced PGHS-2 activity and mRNA and neither PMA-induced, nor constitutive PGHS-2 expression was suppressed by corticosteroids. Actinomycin D-treatment for six hours reduced the PGHS-2 activity and mRNA to only 50% that of untreated cells, suggesting that PGHS-2 mRNA is extremely stable in these cells. HTE cells, at least in vitro, appear unique among prostaglandin-producing cells in that they express PGHS-2, constitutively, independent of regulation by growth factors, serum, or corticosteroids and fail to express PGHS-1 under any culture condition studied.
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