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.