Tsui Ke-Hung, Chung Li-Chuan, Feng Tsui-Hsia, Lee Tzu-Yi, Chang Phei-Lang, Chen Wen-Tsung, Juang Horng-Heng
Department of Urology, Chang Gung Memorial Hospital-Linko, Kwei-Shan, Tao-Yuan, Taiwan; Department of Anatomy, College of Medicine, Chang Gung University, Kwei-Shan, Tao-Yuan, Taiwan.
Prostate. 2015 May;75(6):603-15. doi: 10.1002/pros.22944. Epub 2015 Jan 5.
Liver X receptor (LXR) isoforms, LXRα and LXRβ, have similar protein structures and ligands, but diverse tissue distribution. We used two synthetic, non-steroidal LXR agonists, T0901317 and GW3965, to investigate the effects of LXR agonist modulation on prostate specific antigen (PSA) via the expressions of androgen receptors (AR), LXRα, or LXRβ, in prostate carcinoma cells.
LXRα- or LXRβ-knockdown cells were transduced with specific shRNA lentiviral particles. LXRα and LXRβ expressions were assessed by immunoblotting and RT-qPCR assays. Cell proliferation was determined by (3) H-thymidine incorporation assays. The effects of LXR agonists and epigallocatechin gallate (EGCG) on PSA expression were determined by ELISA, immunoblotting, or transient gene expression assays.
Treatment with either T0901317 or GW3965 significantly attenuated cell proliferation of LNCaP cells. T0901317 treatment suppressed PSA expression while GW3965 treatment enhanced PSA expression. The increase of PSA promoter activity by GW3965 was dependent on the expression of AR. Either LXRα- or LXRβ-knockdown did not affect the activation of androgen on PSA gene expression. However, as compared with mock knockdown-LNCaP cells, the LXRα-knockdown but not the LXRβ-knockdown attenuated the effects of T0901317 and GW3965 on PSA expressions. The effect of GW3965 on PSA expression was blocked by the addition of EGCG.
Our results indicate that T0901317 and GW3965 have divergent effects on PSA expressions. The effects of LXR agonists on PSA expression are LXRα-dependent and AR-dependent. EGCG blocks the inducing effect of GW3965 on PSA expression.
肝脏X受体（LXR）亚型LXRα和LXRβ具有相似的蛋白质结构和配体，但组织分布各异。我们使用两种合成的非甾体LXR激动剂T0901317和GW3965，通过雄激素受体（AR）、LXRα或LXRβ在前列腺癌细胞中的表达，来研究LXR激动剂调节对前列腺特异性抗原（PSA）的影响。
用特异性短发夹RNA慢病毒颗粒转导LXRα或LXRβ敲低细胞。通过免疫印迹和RT-qPCR检测评估LXRα和LXRβ的表达。通过³H-胸腺嘧啶核苷掺入试验测定细胞增殖。通过酶联免疫吸附测定（ELISA）、免疫印迹或瞬时基因表达试验，确定LXR激动剂和表没食子儿茶素没食子酸酯（EGCG）对PSA表达的影响。
用T0901317或GW3965处理可显著减弱LNCaP细胞的增殖。T0901317处理可抑制PSA表达，而GW3965处理则增强PSA表达。GW3965对PSA启动子活性的增加依赖于AR的表达。LXRα或LXRβ敲低均不影响雄激素对PSA基因表达的激活作用。然而，与模拟敲低的LNCaP细胞相比，LXRα敲低而非LXRβ敲低减弱了T0901317和GW3965对PSA表达的影响。添加EGCG可阻断GW3965对PSA表达的作用。
我们的结果表明，T0901317和GW3965对PSA表达具有不同的影响。LXR激动剂对PSA表达的影响是LXRα依赖性和AR依赖性的。EGCG可阻断GW3965对PSA表达的诱导作用。
