Estrogen sulfotransferase (SULT1E1) expression in benign and malignant human bone tumors

Background and Objectives: 17 beta-estradiol regulates growth and differentiation in normal and malignant bone. E2 is inactivated to 17 beta-estradiol-sulfate through estrogen sulfotransferase (SULT1E1). Results: In an explorative study, SULT1E1 mRNA expression was assessed in a broad range of samples from benign, primary and secondary malignant bone tumors. We detected SULT1E1 mRNA in 31/50 tumor samples (10/19 malignant, 6/13 benign tumors; 15/18 metastases). Significantly more SULT1E1-positive samples were found in metastases than in primary bone tumors (P = 0.019). Yet, there was no difference between malignant and benign primary tumors (P = 0.718). SULT1E1 mRNA levels were not related to patients' age, gender, tumor location, stage, grading, and chemotherapy pretreatment. Relative SULT1E1 mRNA levels did not correlate with that of estrogen-receptor alpha (ER alpha) as assessed by quantitative TaqMan PCR (10 malignant, 8 benign tissue samples). In the latter, ER alpha mRNA, but not SULT1E1 mRNA levels were significantly lower than in the malignant samples (P = 0.006 and P=0.71, respectively). Also, pronounced expression of SULTIEI mRNA but not of ERa mRNA was observed in osteosarcoma (MG-63, HOS) and Ewing's sarcoma (TC-71) cells, while human osteoblasts and BMSC contained ERa but not SULT1E1 mRNA. Conclusion: Frequent expression of SULT1E1 mRNA in various human bone tumors suggests that sulfonation might be important to control E2 levels and activity.