Type II estrogen-binding sites in human ovarian cancer: correlation with estrogen, progesterone, and epidermal growth...

Type II estrogen-binding sites (Type II EBS) and the recently identified bioflavonoid-like ligand methyl-p-hydroxyphenyllactate may be regarded as a growth regulatory system active on both normal and neoplastic tissues. It has been reported that, in addition to estrogen and progesterone receptors, primary ovarian cancers also express Type II estrogen binding sites. These sites are able to bind estrogenic compounds and also some naturally occurring flavonoids such as quercetin. In this study we report the presence of cytosolic Type II EBS in a series of 10 normal ovaries, 42 primary ovarian tumors, and 14 metastatic deposits. Scattered levels of Type II EBS were found in normal ovarian tissues (median, 1603 fM/mg protein, range, 271-4943). In primary ovarian tumors and in omental metastases median levels of Type II EBS were 835 fM/mg protein (range, 134-4875) and 758 fM/mg protein (range, 204-2007), respectively. Although Type II EBS tend to be higher in normal than in malignant tissues the difference was not statistically significant. No correlation was found between Type II EBS levels and the common clinicopathological characteristics of the tumors. Moreover there was no relation between Type II EBS and estrogen and epidermal growth factor receptors. A significative inverse correlation with progesterone receptor levels was observed. The presence of Type II EBS in ovarian cancer could be of clinical importance since it has been demonstrated that bioflavonoids, through the interaction with Type II EBS, may exert a growth inhibitory activity both alone or in combination with chemotherapeutic agents on ovarian cancer cell lines and primary tumors.