Expression of somatostatin receptor subtypes 1, 2, 3, and 5 in the hyperplastic and neoplastic endometrium
AL Railton1, I Richmond1, VL Green2 & SL Atkin2
Somatostatin (sst) acts via five G-protein-coupled receptors (sstr) that effect angiogenesis, cell proliferation and apoptosis. We have reported the expression of these receptors in normal endometrium and in this study we have extended those observations to the expression of sstr subtypes 1, 2, 3, and 5 within hyperplastic and neoplastic endometrium using immunohistochemistry. METHOD The avidin-biotin-peroxidase method was used to immunostain formalin-fixed, paraffin-embedded sections of hyperplastic endometrium, consisting of simple (n=10), and complex hyperplasia with (n=8) and without (n=5) as well as endometrial adenocarcinoma (n=14). The staining was scored positive or negative in the glandular epithelium, stroma and endothelium. RESULTS Sstr1, sstr2 sstr3 and sstr5 were expressed in the glandular epithelium of 2/10, 6/10, 2/10 and 1/10 simple hyperplastic samples, 2/5, 4/5, 3/5, and 0/5 complex hyperplastic samples without atypia, 5/8, 6/8, 6/8 and 3/8 atypical hyperplastic samples and 14/14, 14/14, 12/14 and 11/14 neoplastic samples of endometrium, respectively. The stroma appeared to have a lower frequency of expression of sstr1, sstr2, sstr3 and sstr5 with 1/10, 4/10, 3/10 and 1/10 samples of simple hyperplasia, 1/5, 3/5, 4/5 and 2/5 samples of complex hyperplasia without atypia, 1/8, 0/8, 0/8 and 2/8 samples of complex hyperplasia being positive in their stroma. The endothelium of the hyperplastic and neoplastic endometrium displayed very little sstr expression with only 1/10 simple hyperplastic samples positive for sstr2 and sstr3, and 1/5 samples of complex hyperplastic endometrium without atypia positive for sstr3 with the remaining samples being negative for each of the sstrs. CONCLUSION Sstr1, sstr2, sstr3 and sstr5 expression within the glandular epithelium tends to increase between the transition of simple hyperplasia to neoplasia. Less sstr expression was seen in stroma and in the endometrium of the hyperplastic and neoplastic endometrium.