Trasino Steven E, Harrison Earl H, Wang Thomas T Y
Phytonutrients Laboratory, Agricultural Research Service, USDA, Beltsville, MD 20705, USA.
Exp Biol Med (Maywood). 2007 Jun;232(6):762-71.
Previous gene array data from our laboratory identified the retinoic acid (RA) biosynthesis enzyme aldehyde dehydrogenase 1A3 (ALDH1A3) as a putative androgen-responsive gene in human prostate cancer epithelial (LNCaP) cells. In the present study, we attempted to identify if any of the three ALDH1A/RA synthesis enzymes are androgen responsive and how this may affect retinoid-mediated effects in LNCaP cells. We demonstrated that exposure of LNCaP cells to the androgen dihydrotestosterone (DHT) results in a 4-fold increase in ALDH1A3 mRNA levels compared with the untreated control. The mRNA for two other ALDH1A family members, ALDH1A1 and ALDH1A2, were not detected and not induced by DHT in LNCaP cells. Inhibition of androgen receptor (AR) with both the antiandrogen bicalutamide and small interfering RNA for AR support that ALDH1A3 regulation by DHT is mediated by AR. Furthermore, specific inhibition of the extracellular signal-regulated kinase and Src family of kinases with PD98059 and PP1 supports that AR's regulation of ALDH1A3 occurs by the typical AR nuclear-translocation cascade. Consistent with an increase in ALDH1A3 mRNA, DHT-treated LNCaP cells showed an 8-fold increase in retinaldehyde-dependent NAD(+) reduction compared with control. Lastly, treatment of LNCaP with all-trans retinal (RAL) in the presence of DHT resulted in significant up-regulation of the RA-inducible, RA-metabolizing enzyme CYP26A1 mRNA compared with RAL treatment alone. Taken together, these data suggest that (i) the RA biosynthesis enzyme ALDH1A3 is androgen responsive and (ii) DHT up-regulation of ALDH1A3 can increase the oxidation of retinal to RA and indirectly affect RA bioactivity and metabolism.
我们实验室之前的基因芯片数据表明，视黄酸（RA）生物合成酶醛脱氢酶1A3（ALDH1A3）是人类前列腺癌上皮（LNCaP）细胞中一个假定的雄激素反应基因。在本研究中，我们试图确定三种ALDH1A/RA合成酶中是否有任何一种对雄激素有反应，以及这可能如何影响LNCaP细胞中类视黄醇介导的效应。我们证明，与未处理的对照相比，将LNCaP细胞暴露于雄激素双氢睾酮（DHT）会导致ALDH1A3 mRNA水平增加4倍。在LNCaP细胞中未检测到另外两个ALDH1A家族成员ALDH1A1和ALDH1A2的mRNA，且它们也不会被DHT诱导。用抗雄激素比卡鲁胺和针对雄激素受体（AR）的小干扰RNA抑制AR，支持DHT对ALDH1A3的调节是由AR介导的。此外，用PD98059和PP1特异性抑制细胞外信号调节激酶和Src激酶家族，支持AR对ALDH1A3的调节是通过典型的AR核转位级联发生的。与ALDH1A3 mRNA的增加一致，与对照相比，经DHT处理的LNCaP细胞中视黄醛依赖性NAD(+)还原增加了8倍。最后，与单独用全反式视黄醛（RAL）处理相比，在DHT存在下用RAL处理LNCaP导致RA诱导的、RA代谢酶CYP26A1 mRNA显著上调。综上所述，这些数据表明：（i）RA生物合成酶ALDH1A3对雄激素有反应；（ii）DHT对ALDH1A3的上调可增加视黄醛向RA的氧化，并间接影响RA的生物活性和代谢。
