Expression of receptor-binding cancer antigen expressed on SiSo cells in endometrial carcinoma and the correlation thereof with the expression of estrogen receptor subtypes

Abstract

To investigate the expression of receptor-binding cancer antigen expressed on SiSo cells (RCAS1) and estrogen receptor subtypes in normal, hyperplastic, and carcinomatous endometrium and to explore their possible roles in carcinogenesis and progression of endometrial carcinoma. Immunohistochemistry and semi-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) were applied to detect the protein and mRNA expression of RCAS1, estrogen receptor (ER) alpha and ERbeta in 20 specimens of normal endometrium, 24 specimens of hyperplastic endometrium, and 50 specimens of carcinomatous endometrium. Western blotting was used to detect the RCAS1 protein expression. Normal endometrium and simple and complex hyperplastic endometrium showed a P pattern of RCAS1 expression; carcinomatous endometrium showed the D pattern; and the atypical hyperplastic endometrium showed both, 30% (6/20) of which showed D pattern. The high level RCAS1 protein expression rates of the normal, simple and complex hyperplasia, atypical hyperplasia, and endometrial carcinoma were 0% (0/20), 9.1% (2/22), 45.0% (9/20), and 68.0% (34/50) respectively with a significant difference between any 2 groups (all P < 0.05). The high level expression of RCAS1 was detected more frequently in the carcinomatous endometrium with deep myometrial invasion, vascular invasion, and positive of ERalpha (all P < 0.05). The Western blotting and RT-PCR results were correlated with the immunohistochemistry results. The RCAS1 mRNA level was positively correlated with the ERalphamRNA level (P < 0.01), but not correlated with the ERbetamRNA level (P > 0.05). The expression and distribution of RCAS1 may be involved in the malignant transformation of endometrium, and RCAS1 coexpression with ERalpha may be associated with the development and metastasis of endometrial carcinoma.