OBJECTIVE: To detect the expression of estrogen sulfotransferase (EST) in breast tissues, and to investigate its significance in breast carcinogenesis and the relationship between EST mRNA and estrogen.METHODS: Seven specimens of normal human breast tissues from patients with benign breast diseases were implanted subcutaneously into athymic nude mice, one specimen divided into many pieces to be implanted into 2 groups of mice, totalling 14 mice. Then the 14 mice were divided into 2 groups: as control and the other injected intramuscularly with estradiol benzoate (B-E(2)) every other day for 6 weeks. Six weeks after, the implanted tissues were taken out. Reverse transcription polymerase chain reaction (RT-PCR) was used to detect the expression of EST mRNA in 24 specimens of breast cancer, 6 specimens of normal breast tissues around the breast fibroadenoma, all resected during operation, and the specimens of implanted normal breast tissues from the mice (control group and B-E(2) group). The protein expression of estrogen receptor (ER) was detected by immunohistochemistry in the 24 specimens of breast cancer.RESULTS: EST mRNA was expressed in all normal human breast tissues and the expression was increased in the grafts from mice of B-E(2) group. However, the specimens of breast cancer showed decrease or absence of EST mRNA expression.CONCLUSION: EST mRNA expression is decreased or lost in breast cancer tissues. EST mRNA can be regulated by estrogen in normal breast tissues.
Adult Breast