Roger C, Lambard S, Bouskine A, Mograbi B, Chevallier D, Nebout M, Pointis G, Carreau S, Fenichel P
INSERM U 670, 28 avenue de Valombrose, Faculté de Médecine, 06102 Nice Cedex 2, France.
J Mol Endocrinol. 2005 Aug;35(1):191-9. doi: 10.1677/jme.1.01704.
It is now well established that estrogens participate in the control of normal spermatogenesis and endogenous or environmental estrogens are involved in pathological germ cell proliferation including testicular germ cell tumors. Studying a human testicular seminoma cell line, JKT-1, we show here that 17beta-estradiol (10(-12) to 10(-6) M) induced in vitro a significant dose-dependent decrease of cell growth. This antiproliferative effect was maximum after 4 days of exposure at a physiologically intratesticular concentration of 10(-9) M, close to the K(d) of ER, and reversed by ICI 182780, an ER antagonist, suggesting an ER-mediated pathway. By RT-PCR and Western blot we were able to confirm that JKT-1, like tumoral seminoma cells and normal human testicular basal germ cells, expresses estrogen receptor beta (ERbeta), including ERbeta1 and ERbeta2, a dominant negative variant, but not ERalpha. Using immunofluorescence and confocal microscopy, ERbeta was observed as perinuclear intracytoplasmic spots in JKT-1 and tumoral seminoma cells without significant translocation of ERbeta into the nucleus, under 17beta-estradiol exposure. Double staining observed by confocal microscopy revealed that ERbeta colocalized in JKT-1 cells with cytochrome C, a mitochondrial marker. We report for the first time the expression of a functional aromatase complex in seminoma cells as assessed by RT-PCR, Western blot and enzymatic assay. Seminoma cells are able to respond to estrogens through a possible autocrine or paracrine loop. These preliminary results support estrogen-dependency of human testicular seminoma, the most frequent tumor of young men, and suggest potential pharmacological use. Whether this estrogen control, however, involves an ERbeta-mediated stimulation of cell apoptosis and/or an ERbeta-mediated inhibition of cell proliferation, remains to be further determined.
现已充分证实，雌激素参与正常精子发生的调控，内源性或环境雌激素与包括睾丸生殖细胞肿瘤在内的病理性生殖细胞增殖有关。在研究人睾丸精原细胞瘤细胞系JKT - 1时，我们在此表明，17β - 雌二醇（10⁻¹²至10⁻⁶ M）在体外诱导细胞生长出现显著的剂量依赖性降低。这种抗增殖作用在生理睾丸内浓度10⁻⁹ M（接近雌激素受体的解离常数K(d)）下暴露4天后达到最大，并被雌激素受体拮抗剂ICI 182780逆转，提示这是一条由雌激素受体介导的途径。通过逆转录 - 聚合酶链反应（RT - PCR）和蛋白质免疫印迹法（Western blot），我们能够证实，JKT - 1与肿瘤性精原细胞瘤细胞和正常人类睾丸基底生殖细胞一样，表达雌激素受体β（ERβ），包括ERβ1和ERβ2（一种显性负变体），但不表达ERα。利用免疫荧光和共聚焦显微镜观察，在17β - 雌二醇暴露下，ERβ在JKT - 1和肿瘤性精原细胞瘤细胞中表现为核周胞质内斑点，而ERβ没有明显转运至细胞核内。共聚焦显微镜观察的双重染色显示，ERβ在JKT - 1细胞中与线粒体标记物细胞色素C共定位。我们首次通过RT - PCR、Western blot和酶活性测定评估，报道了精原细胞瘤细胞中功能性芳香化酶复合物的表达。精原细胞瘤细胞能够通过可能的自分泌或旁分泌环对雌激素作出反应。这些初步结果支持人类睾丸精原细胞瘤（年轻男性最常见的肿瘤）对雌激素的依赖性，并提示其潜在的药理学用途。然而，这种雌激素调控是否涉及ERβ介导的细胞凋亡刺激和/或ERβ介导的细胞增殖抑制，仍有待进一步确定。
