Expression of estrogen receptor (ER) in oral mucose and salivary glands

Objectives: To assess the expression of estrogen receptor (ER) in oral muco sa and salivary glands, buccal mucosal biopsies from ten postmenopausal wom en (taken before and during the hormone replacement therapy), as well as, s ingle biopsies from 20 healthy 19-year-old women were analyzed for ER expre ssion. Salivary gland biopsies were taken from the minor labial salivary gl ands (n = 6), submandibular glands (n = 5) and parotid gland (n = I) from w omen at different ages. Methods: total RNA extracted from the tissue sample s was reverse-transcribted (RT) to single-stranded cDNA, and the RT-polymer ase chain reaction (RT-PCR) product was subjected to nucleotide sequencing to confirm the match with ER cDNA. Immunohistochemistry (IHC) with a monocl onal ER antibody (ER-ICA, Abbott) and Western blot analysis with monoclonal antibody against ER-related antigen (ER-D5, Amersham) were performed on th e biopsies taken from the postmenopausal women. Results: ER mRNA was expres sed in 18/20 (90%) and 20/20 (100%) of the mucosal biopsies in the postmeno pausal and 19-year-old women, respectively. The expression of mRNA was dete cted in all the submandibular gland samples, in the single parotid gland, a s well as, in 4/6 (67%) of the labial glands. ER expression could not be de tected by IHC, indicating either a very low level of expressed protein or d ifficulties in recognizing the epitopes by IHC. However, Western blot demon strated 8/8 (100%) of the mucosal biopsies of postmenopausal women positive for ER-related antigen. Conclusions: the presence of ER mRNA and immunorea ctive ER protein suggests that estrogens have a biological role in oral muc osa and salivary glands: (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.