The sulfatase pathway as estrogen supply in endometrial cancer.

Contradictory results are reported about the level of steroid sulfatase (STS), estrogen sulfotransferase (SULT1E1; together, the sulfatase pathway) and aromatase (CYP19A1) in endometrial cancer (EC). The aim of this study was to explore the levels of these enzymes in a well-characterized cohort of EC patients and postmenopausal controls. Endometrial tissues from 31 EC patients (21 grade 1 and 10 grade 2-3) and 19 postmenopausal controls were collected. Levels of mRNA (RT-qPCR) and protein (immunohistochemistry) were determined. STS enzyme activity was measured by HPLC, whereas SULT1E1 enzyme activity was determined using a novel method based on liquid chromatography-mass spectrometry (LC-MS/MS). No significant differences in STS, SULT1E1 mRNA or protein levels and STS:SULT1E1 ratio were found. STS enzyme activity and STS:SULT1E1 activity ratio were significantly decreased in ECs compared with controls. CYP19A1 mRNA levels were lower in ECs than in controls. A novel highly sensitive and accurate protocol to assess SULT1E1 activity is presented. STS enzyme activity and the STS:SULT1E1 activity ratio seem to be lower in ECs than in controls. STS is an important route for estrogen supply in endometrial cells.