1 This study demonstrates the localization of the prostaglandin (PG)D-2 rec
eptor (DP) within the mucous-secreting globlet cells of the human colon by
in situ hybridization, which suggests a role for DP in mucous secretion. Se
lective high affinity ligands were used, therefore, to evaluate DP regulati
on of mucous secretion in LS174T human colonic adenocarcinoma cells.
2 The expression of hDP in LS174T cells was confirmed at the mRNA level by
reverse transcriptase-polymerase chain reaction, and at the protein level b
y radioligand binding assays and signal transduction (cyclic AMP accumulati
on) assays. PGD(2) and the highly selective DP-specific agonist L-644,698 (
(4-(3-(3-(3-hydroxyoctyl)-4-oxo-2-thiazolidinyl) propyl) benzoic acid) (rac
emate), but not PGE(2) competed for [H-3]-PGD(2)-specific binding to LS174T
cell membranes (K-i values of 0.4 nM and 7 nM, respectively). The DP-speci
fic agonists PGD(2), PGJ(2), BW245C (5-(6-carboxyhexyl)-1-(3-cyclohexyl-3-h
ydroxypropylhydantoin)), and L-644,698 showed similar potencies in stimulat
ing cyclic AMP accumulation (EC50 values: 45-90 nM) and demonstrated the ex
pected rank order of potency. PGE(2) also elicited cyclic AMP production in
this cell line (EC50 value: 162 nM).
3 The activation of cyclic AMP production by PGD(2) and L-644,698, but not
PGE(2), was inhibited by the selective DP antagonist BW A868C. Thus, PGD(2)
and L-644,698 act through hDP in LS174T cells. PGD(2), L-644,698 and PGE(2
) tan established mucin secretagogue) potently stimulated mucin secretion i
n LS174T cells in a concentration-dependent manner (EC50<50nM). However, BW
A868C effectively antagonized only the mucin secretion mediated by PGD(2)
and L-644,698 and not PGE(2). These data support a role for the DP receptor
in the regulation of mucous secretion.