Expression of estrogen receptor (ER) in oral mucosa and salivary glands.
OBJECTIVE
To assess the expression of estrogen receptor (ER) in oral mucosa and salivary glands, buccal mucosal biopsies from ten postmenopausal women (taken before and during the hormone replacement therapy), as well as, single biopsies from 20 healthy 19-year-old women were analyzed for ER expression. Salivary gland biopsies were taken from the minor labial salivary glands (n=6), submandibular glands (n=5) and parotid gland (n=1) from women at different ages.


METHODS
total RNA extracted from the tissue samples was reverse-transcripted (RT) to single-stranded cDNA, and the RT-polymerase chain reaction (RT-PCR) product was subjected to nucleotide sequencing to confirm the match with ER cDNA. Immunohistochemistry (IHC) with a monoclonal ER antibody (ER-ICA, Abbott) and Western blot analysis with monoclonal antibody against ER-related antigen (ER-D5, Amersham) were performed on the biopsies taken from the postmenopausal women.


RESULTS
ER mRNA was expressed in 18/20 (90%) and 20/20 (100%) of the mucosal biopsies in the postmenopausal and 19-year-old women, respectively. The expression of mRNA was detected in all the submandibular gland samples, in the single parotid gland, as well as, in 4/6 (67%) of the labial glands. ER expression could not be detected by IHC, indicating either a very low level of expressed protein or difficulties in recognizing the epitopes by IHC. However, Western blot demonstrated 8/8 (100%) of the mucosal biopsies of postmenopausal women positive for ER-related antigen.


CONCLUSIONS
the presence of ER mRNA and immunoreactive ER protein suggests that estrogens have a biological role in oral mucosa and salivary glands.
Leimola-Virtanen
R
R
Department of Oral Pathology, Institute of Dentistry and Medicity Research Laboratory, University of Turku, Lemminkäisenkatu 2, FIN-20520, Turku, Finland. riita.leimola-virtanen@utu.fi
Salo
T
T
Toikkanen
S
S
Pulkkinen
J
J
Syrjänen
S
S
D000911:Antibodies, Monoclonal; D015153:Blotting, Western; D005260:Female; D015870:Gene Expression; D020249:Hormone Replacement Therapy; D006801:Humans; D007150:Immunohistochemistry; D008875:Middle Aged; D009061:Mouth Mucosa / Q000378:metabolism* / Q000473:pathology; D017698:Postmenopause; D012333:RNA, Messenger / Q000032:analysis; D011960:Receptors, Estrogen / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012469:Salivary Glands / Q000378:metabolism* / Q000473:pathology
D000911:Antibodies, Monoclonal; D012333:RNA, Messenger; D011960:Receptors, Estrogen