The human STS gene is localized on the X-chromosome and consists of 10 exons. Inactivating mutations in STS gene have been associated with X-linked ichthyosis. Six different promoters were detected to drive STS expression giving rise to transcripts with unique first exons, and exon 1 alpha was associated with the promoter that drives expression in the placenta [ 24 ]. Induction of STS transcription by estradiol through binding to ER and via activation of estrogen-response elements in the promoter region results in driving the 1a and 1b transcripts in breast carcinoma [ 25 ]. Furthermore, regulation of STS activity by tumor necrosis factor alpha and interleukin 6 was found in breast cancer, most likely through a posttranslational modification [ 26 ].
Placental steroid sulfatase deficiency is a genetic disorder only recently reported in the medical literature. Most documented cases of placental sulfatase deficiency have been marked by delay in onset of labor, lack of cervical dilatation, and relative refractoriness of oxytocic agents and amniotomy. We have studied the placenta, cultured fibroblasts, and amniotic fluid cells from an affected patient. The activities of estrone sulfatase, pregnenolone sulfatase, dehydroepiandrosterone sulfatase, and arylsulfatase C in the placenta from the patient were severely deficient. Arylsulfatases A and B were present at levels within the normal range for this tissue. Fibroblast dehydroepiandrosterone sulfatase activity was virtually absent in the patient's cells and present at normal levels in individuals with a variety of lysosomal disorders. It would thus appear that the mutation responsible for steroid sulfatase deficiency is genetically and biochemically distinct from those involved in the lysosomal sulfatase deficiency states. The cell culture studies further suggest that the defect is a generalized one which should be detectable in midtrimester of pregnancy and may have phenotypic consequences in later postnatal life.