Cancer and Inflammation Program, School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, New Territories, Hong Kong, China.
Cancer Lett. 2011 May 1;304(1):8-20. doi: 10.1016/j.canlet.2011.01.003. Epub 2011 Feb 25.
Although estrogens have been long implicated in the prostate carcinogenesis, direct evidence showing their carcinogenicity on prostatic epithelial cells has not yet been clearly demonstrated. In this study, we treated an immortalized, non-transformed and androgen-responsive rat prostatic epithelial cell line NRP-152 with 17β-estradiol (E2) at concentrations 1-3 microM for period 2-6 weeks. After in vitro treatment, we evaluated the anchorage-independent growth of E2-treated NRP-152 cells by soft agar assay and isolated the colonies formed by the transformed E2-NRP-152 cells in soft agar for further growth phenotype characterization. Our results showed that the isolated E2-NRP-152 clones displayed neoplastic transformation phenotype, as demonstrated by their capacity of forming colonies in soft agar and tumors in immunodeficient nude mice, while losing their spheroid formation capacity in Matrigel 3D-culture. Western blot and RT-PCR analyses showed that the transformed E2-NRP-152 cells expressed increased levels of ERα and several putative prostate cancer stem cell markers (integrins α2β1, CD44, CD133, ABCG2 and CXCR4) but decreased levels of ERβ and AR. Comet assay revealed that E2-treatment also induced formation of comet cells, indicating that E2 caused DNA damage to the NRP-152 cells. Our present findings demonstrated that in vitro E2 exposure could neoplastically transform the rat prostatic epithelial cells, indicating that E2 is carcinogenic to the prostatic epithelial cells.
尽管雌激素长期以来一直被认为与前列腺癌的发生有关，但直接证明其对前列腺上皮细胞致癌性的证据尚未得到明确证实。在这项研究中，我们用 17β-雌二醇（E2）处理一种永生化、非转化且对雄激素有反应的大鼠前列腺上皮细胞系 NRP-152，浓度为 1-3 μM，处理时间为 2-6 周。体外处理后，我们通过软琼脂试验评估 E2 处理的 NRP-152 细胞的无锚定依赖性生长，并分离软琼脂中形成的转化 E2-NRP-152 细胞的集落，以进一步进行生长表型特征分析。我们的结果表明，分离的 E2-NRP-152 克隆显示出肿瘤转化表型，这表现为它们在软琼脂中形成集落和在免疫缺陷裸鼠中形成肿瘤的能力，而在 Matrigel 3D 培养中失去了球体形成能力。Western blot 和 RT-PCR 分析表明，转化的 E2-NRP-152 细胞表达了更高水平的 ERα 和几种潜在的前列腺癌干细胞标记物（整合素 α2β1、CD44、CD133、ABCG2 和 CXCR4），但 ERβ 和 AR 的水平降低。彗星试验显示，E2 处理还诱导了彗星细胞的形成，表明 E2 对 NRP-152 细胞造成了 DNA 损伤。我们的研究结果表明，体外 E2 暴露可以使大鼠前列腺上皮细胞发生肿瘤转化，表明 E2 对前列腺上皮细胞具有致癌性。
