Expression and Regulation of Constitutive and Acute Phase Serum Amyloid A mRNAs in Hepatic and Non‐Hepatic Cell Lines

‘Acute phase’ and ‘constitutive’ SAA (A-SAA and C-SAA, respectively) mRNA levels were measured in hepatic and non-hepatic cell lines after treatment with monocyte conditioned medium (MoCM), with or without dexamethasone (Dex). A-SAA mRNAs were detected in MoCM-treated hepatoma cell lines (PLC/PRF/5, HuH7, HepG2, and Hep3B), a fibroblast cell line (MRC5), six epithelial cell lines (RT4/31, SW13, Hela Ohio, HCT-8, CaCo2, and KB), and an endothelial cell line ECV304. In KB cells, Dex alone caused a dramatic increase in A-SAA mRNA levels. C-SAA was detected in all hepatic and non-hepatic cell lines. Two differentially regulated size classes of C-SAA mRNA were detected in the hepatoma cell lines. A-SAA mRNA levels were measured in ECV304 cells treated with IL-1β, IL-6, TNFα and Dex, in various combinations, and revealed different profiles to those seen for hepatic cells. The extent of polyadenylation of A-SAA mRNA in ECV304 and KB cells differed whereas the polyadenylation of C-SAA mRNA remained constant. These data suggest that the parameters that determine the steady state mRNA levels and post-transcriptional regulation of A-SAA and C-SAA mRNAs are different and are cell type specific.