Department of Pharmaceutical Sciences, School of Pharmacy, University of Colorado Denver, USA.
Cancer Prev Res (Phila). 2011 Aug;4(8):1222-32. doi: 10.1158/1940-6207.CAPR-10-0370. Epub 2011 May 5.
The epithelial-to-mesenchymal transition (EMT) in prostate cancer (PCA) cells is considered prerequisite for acquiring migratory/invasive phenotype, and subsequent metastasis. We hypothesized that promoting the E-cadherin expression in PCA cells by using nontoxic phytochemicals, like silibinin, would prevent EMT and consequently invasiveness. Our results showed that silibinin treatment (5-90 μmol/L) significantly inhibits migratory and invasive potential of advance human PCA PC3, PC3MM2, and C4-2B cells in in vitro assays. Importantly, the antimigratory/antiinvasive efficacy of silibinin was not due to its cytotoxicity toward PCA cells. Molecular analyses showed that silibinin increases E-cadherin level that was localized mainly at cellular membrane as evidenced by subcellular fractional and confocal analyses in PC3 cells, which might be responsible for morphologically observed shift toward epithelial character. Silibinin also decreased the levels of Slug, Snail, phospho-Akt(ser(473)), nuclear β-catenin, phospho-Src(tyr(419)) and Hakai; together they play an important role in regulating E-cadherin expression/function and EMT. Similar silibinin effects on E-cadherin, β-catenin, phospho-Src(tyr(419)), and Hakai levels were also observed in PC3MM2 and C4-2B PCA cells. Selective Src inhibition by dasatinib also showed increased E-cadherin expression in PC3 cells suggesting a possible involvement of Src inhibition in silibinin-caused increase in E-cadherin level. Additional studies in PC3 cells with stable knock-down of E-cadherin expression revealed that antimigratory/antiinvasive efficacy of silibinin is in-part dependent on E-cadherin expression. Together, our results showing antimigratory/antiinvasive effects of silibinin and associated mechanisms suggest that silibinin should be tested further in clinically relevant animal models toward exploiting its potential benefits against metastatic PCA.
前列腺癌细胞的上皮-间充质转化 (EMT) 被认为是获得迁移/侵袭表型以及随后转移的先决条件。我们假设，使用非毒性植物化学物质，如水飞蓟素，促进 PCA 细胞中 E-钙粘蛋白的表达，将阻止 EMT 并因此阻止侵袭性。我们的结果表明，水飞蓟素处理（5-90 μmol/L）显著抑制了体外试验中高级人 PCA PC3、PC3MM2 和 C4-2B 细胞的迁移和侵袭潜力。重要的是，水飞蓟素的抗迁移/抗侵袭作用不是由于其对 PCA 细胞的细胞毒性。分子分析表明，水飞蓟素增加了 E-钙粘蛋白的水平，该水平主要定位于细胞膜上，这可以通过亚细胞分级和 PC3 细胞的共聚焦分析来证明，这可能是形态上观察到的向上皮特征转变的原因。水飞蓟素还降低了 Slug、Snail、磷酸化-Akt(ser(473))、核 β-连环蛋白、磷酸化-Src(tyr(419)) 和 Hakai 的水平；它们共同在调节 E-钙粘蛋白表达/功能和 EMT 中发挥重要作用。在 PC3MM2 和 C4-2B PCA 细胞中也观察到了类似的水飞蓟素对 E-钙粘蛋白、β-连环蛋白、磷酸化-Src(tyr(419)) 和 Hakai 水平的影响。Src 的选择性抑制剂 dasatinib 也显示出在 PC3 细胞中 E-钙粘蛋白表达增加，这表明 Src 抑制可能参与了水飞蓟素引起的 E-钙粘蛋白水平增加。在具有稳定敲低 E-钙粘蛋白表达的 PC3 细胞中的进一步研究表明，水飞蓟素的抗迁移/抗侵袭作用在一定程度上依赖于 E-钙粘蛋白的表达。总之，我们的研究结果表明，水飞蓟素的抗迁移/抗侵袭作用及其相关机制表明，应该在临床相关的动物模型中进一步测试水飞蓟素，以利用其对转移性 PCA 的潜在益处。
