17β-Hydroxysteroid dehydrogenase type I and aromatase in ovarian cortical inclusion cysts

Previous evidence suggests a link between the ovarian surface epithelium and cortical inclusion cysts and the origin of epithelial ovarian cancer. The presence of 17β-hydroxysteroid dehydrogenase type I, aromatase and estrogen receptor alpha has previously been demonstrated in these epithelial components of the human ovary. The aim of this study was to provide further evidence on these enzymes involved in estrogen biosynthesis and the estrogen receptor in cortical inclusion cysts and the ovarian surface epithelium in the ovaries of women between the ages of 23 and 80. Our results were obtained via immunohistochemistry of formalin-fixed, paraffin-embedded tissue samples from patients who underwent medically indicated oophorectomy. The observed frequencies of cortical inclusion cysts within the ovarian cortex did not reveal significant variation with patient age. The presence of HSD17B1, aromatase and estrogen receptor alpha was observed in more than 60% of the cortical inclusion cysts, with a higher frequency than that of the ovarian surface epithelium. The highest frequency was observed in cortical inclusion cysts with tubal-like epithelium. The estrogen receptor distribution was determined in the ovary stroma, and 17β-hydroxysteroid dehydrogenase type 1 was also identified in the stromal cells. The expression of estrogen receptor alpha in the cortical inclusion cysts was reduced in patients with cervical squamous cell carcinoma. This evidence supports the involvement of estrogen in the biology of the ovarian surface epithelium and cortical inclusion cysts in the ovary.