PPARγ和RXR激动剂抑制人卵巢颗粒细胞芳香化酶活性和其mRNA的水平

Inhibition of PPARγ and RXR agonists on aromatase activity and its mRNA transcriptional level in human ovarian granulosa cells

目的 探讨过氧化酶体增殖物激活受体γ(PPARγ)和维甲类X受体 (RXR)激动剂对人卵巢颗粒细胞芳香化酶活性的调节作用。方法 测定人卵巢颗粒细胞 (KGN)在PPARγ激动剂曲格列酮、吡格列酮和前列腺素J2 以及RXR激动剂LG10 0 2 68处理前后芳香化酶活性、雌酮 (E1)的变化以及P45 0芳香化酶 (P45 0arom)mRNA的表达水平。对P45 0arom启动子Ⅱ进行分析 ,以确定PPARγ和RXR是否直接抑制P45 0arommRNA的转录。结果 (1)PPARγ激动剂和RXR激动剂均能显著抑制芳香化酶活性 ,两者结合使用抑制作用进一步增强并且使E1的生成减少 ;(2 )芳香化酶活性的降低与P45 0arommRNA水平下降有关 ;(3 )PPARγ和RXR激动剂对 1.0kb长的P45 0arom启动子Ⅱ控制的荧光素酶蛋白无调节作用。结论 PPARγ和RXR激动剂对人卵巢颗粒细胞的芳香化酶活性和P45 0arommRNA的水平有抑制作用。

Objective To investigate the regulatory effects of peroxisome-proliferator activated receptor γ (PPARγ) and retinoid X receptor (RXR) agonists on the aromatase activity in human ovarian granulosa cells. Methods Human ovarian granulosa cancer cells, named KGN cells, were treated with PPARγ agonists including troglitazone (TGZ), pioglitazone and prostaglandin J_2 (PGJ_2), and RXR agonist LG100268 for various durations. The culture media were then collected for analysis of the aromatase activity determined by measuring the 〔 3H〕H_2O released upon the conversion of 〔1β- 3H〕 androstenedion to estrone (E_1), and the E_1 production was determined by radioimmunoassay. In order to determine whether or not PPARγ and RXR directly inhibited P450aromatase (P450arom) mRNA transcription, P450arom promotor Ⅱ was analysed. Results (1) PPARγ agonists including TGZ, pioglitazone and PGJ_2, or RXR agonist LG100268 alone significantly inhibited the aromatase activity in cultured KGN cells, while combined treatment with both PPARγ agonist and LG100268 caused a much greater inhibition on the aromatase activity and a decrease of the E_1 production; (2) The changes in the aromatase activity were associated with comparable changes in the P450arom mRNA level based on a RNase protection assay and (3) The luciferase activity driven by P450arom promoter Ⅱ (1.0 kb) was not decreased by adding PPARγ and RXR agonists in transfected KGN cells either at basic state or in the state stimulated by forskolin. Conclusion PPARγ and RXR agonists inhibite the aromatase activity and decrease the level of P450arom mRNA.