The effect of 16,16'-dimethyl prostaglandin E2 (dmPGE2) on the human colonic adenocarcinoma derived mucus-secreting goblet cell line HT29-18N2 was investigated. The proliferation rate of HT29-18N2 was increased by exposure to 10 or 100 microM dmPGE2. Exposure to 10 or 100 microM dmPGE2 caused a significant decrease in the rate of radiolabeled glucosamine incorporation into newly synthesized glycoproteins during an 8 or 24 h exposure. At concentrations as low as 1 microM, dmPGE2 accelerated the secretion of mucin glycoproteins as assessed by the release of newly synthesized radiolabeled glycoproteins, a mucin-specific enzyme-linked immunoassay and a whole-mount immunofluorescence assay. A 1 h exposure to dmPGE2 did not, however, result in a morphometrically detectable decrease in intracellular mucous granule stores or elicit any other readily detectable morphological change. The experimental results suggest elevated levels of PGs may contribute to the previously recognized decreases in intracellular mucin stores and shifts in the types of mucins species present at sites of mucosal inflammation in ulcerative colitis patients.