Steroid sulfatase (EC 3.1.6.2) is an
enzyme that removes the
sulfate group from 3beta-hydroxysteroid
sulfates. This
enzyme is best known for its role in
estrogen production via the fetal adrenal-placental pathway during pregnancy; however, it also has important functions in other physiological and pathological
steroid pathways. The objective of this study was to examine the distribution of
steroid sulfatase in normal human tissues and in breast
cancers using immunohistochemistry, employing a newly developed
steroid sulfatase antibody. A rabbit polyclonal antiserum was generated against a
peptide representing a conserved region of the
steroid sulfatase protein. In Western blotting experiments using human placental microsomes, this antiserum crossreacted with a 65 kDa
protein, the reported size of
steroid sulfatase. The antiserum also crossreacted with single
protein bands in Western blots of microsomes from two human
breast cancer cell lines (MDA-MB-231 and MCF-7) and from rat liver; however, there were some size differences in the immunoreactive bands among tissues. The
steroid sulfatase antibody was used in immunohistochemical analyses of individual human tissue slides as well as a human tissue microarray. For single tissues, human placenta and liver showed strong positive staining against the
steroid sulfatase antibody. ER+/PR+ breast
cancers also showed relatively strong levels of
steroid sulfatase immunoreactivity. Normal human breast showed moderate levels of
steroid sulfatase immunoreactivity, while ER-/PR-
breast cancer showed weak immunoreactivity. This confirms previous reports that
steroid sulfatase is higher in
hormone-dependent breast
cancers. For the tissue microarray, most tissues showed some detectable level of
steroid sulfatase immunoreactivity, but there were considerable differences among tissues, with skin, liver and lymph nodes having the highest immunoreactivity and brain tissues having the lowest. These data reveal the utility of immunohistochemistry in evaluation of
steroid sulfatase activity among tissues. The newly developed antibody should be useful in studies of both humans and rats.