M. Nagano et al., EXPRESSION OF PROLACTIN AND GROWTH-HORMONE RECEPTOR GENES AND THEIR ISOFORMS IN THE GASTROINTESTINAL-TRACT, American journal of physiology: Gastrointestinal and liver physiology, 31(3), 1995, pp. 431-442
Distribution of transcripts for prolactin and growth hormone receptors
(PRLR and GHR) and their isoforms was characterized in the gastrointe
stinal (GI) tract from several species by reverse transcription-polyme
rase chain reaction combined with Southern analysis. Human, rabbit, an
d fetal and adult rat PRLR and GHR transcripts were detected in isolat
ed gastric glands, gastric cell fractions, and intestinal mucosa linea
ges. Human PRLR and GHR transcripts were also observed throughout the
cancerous progression of the colonic and gastric mucosa from adenomas
to colonic liver metastasis and gastrointestinal cancer cell lines at
various stages of growth and differentiation. Prolactin (PRL) produced
no detectable effect on M1 gastric mucin secretion in HT-29 cells ada
pted to methotrexate (HT-29-MTX) or on acid secretion in isolated rabb
it parietal cells. GHRd3, an isoform of human GHR transcript missing e
xon 3, was also broadly expressed and was the only form found in gastr
ic and colorectal adenocarcinomas. Interestingly, several extra bands
of polymerase chain reaction products of the human PRLR, which were sm
aller than the expected size, were observed not only in the GI tract b
ut also in liver and T-47D breast cancer cells. These products from hu
man intestinal and breast cancer cell lines were subsequently subclone
d and sequenced, and we isolated six isoforms of the receptor transcri
pts. One of these clones encodes a putative human PRL binding protein.
The expression of PRL and PRLR transcripts was also clearly observed
in intraepithelial lymphocytes purified from the mouse intestine. The
widespread expression of the PRL and GH receptor transcripts in gastri
c and intestinal mucosal lineages, particularly in epithelia, suggests
regulatory roles of these hormones on digestive and immune functions,
including metabolism, growth, or differentiation.