Erdmann Kati, Kaulke Knut, Rieger Christiane, Salomo Karsten, Wirth Manfred P, Fuessel Susanne
Department of Urology, Technische Universität Dresden, Fetscherstr. 74, 01307, Dresden, Germany.
J Cancer Res Clin Oncol. 2016 Nov;142(11):2249-61. doi: 10.1007/s00432-016-2222-4. Epub 2016 Aug 25.
The tumor-suppressive microRNAs miR-26a and miR-138 are significantly down-regulated in prostate cancer (PCa) and have been identified as direct regulators of enhancer of zeste homolog 2 (EZH2), which is a known oncogene in PCa. In the present study, the influence of miR-26a and miR-138 on EZH2 and cellular function including the impact on the cell cycle regulating network was evaluated in PCa cells.
PC-3 and DU-145 PCa cells were transfected with 100 nM of miRNA mimics, siRNA against EZH2 (siR-EZH2) or control constructs for 4 h. Analyses of gene expression and cellular function were conducted 48 h after transfection.
Both miRNAs influenced the EZH2 expression and activity only marginally, whereas siR-EZH2 led to a notable decrease of the EZH2 expression and activity. Both miRNAs inhibited short- and/or long-term proliferation of PCa cells but showed no effect on viability and apoptosis. In PC-3 cells, miR-26a and miR-138 caused a significant surplus of cells in the G0/G1 phase of 6 and 12 %, respectively, thus blocking the G1/S-phase transition. Treatment with siR-EZH2 was without substantial influence on cellular function and cell cycle. Therefore, alternative target genes involved in cell cycle regulation were identified in silico. MiR-26a significantly diminished the expression of its targets CCNE1, CCNE2 and CDK6, whereas CCND1, CCND3 and CDK6 were suppressed by their regulator miR-138.
The present findings suggest an anti-proliferative role for miR-26a and miR-138 in PCa by blocking the G1/S-phase transition independent of EZH2 but via a concerted inhibition of crucial cell cycle regulators.
肿瘤抑制性 microRNA miR - 26a 和 miR - 138 在前列腺癌（PCa）中显著下调，并已被确定为zeste 同源物 2（EZH2）增强子的直接调节因子，EZH2 是 PCa 中一种已知的致癌基因。在本研究中，评估了 miR - 26a 和 miR - 138 对 EZH2 以及细胞功能（包括对细胞周期调节网络的影响）在 PCa 细胞中的作用。
将 100 nM 的 miRNA 模拟物、针对 EZH2 的 siRNA（siR - EZH2）或对照构建体转染至 PC - 3 和 DU - 145 PCa 细胞中 4 小时。转染后 48 小时进行基因表达和细胞功能分析。
两种 microRNA 对 EZH2 的表达和活性影响甚微，而 siR - EZH2 导致 EZH2 的表达和活性显著降低。两种 microRNA 均抑制 PCa 细胞的短期和/或长期增殖，但对细胞活力和凋亡无影响。在 PC - 3 细胞中，miR - 26a 和 miR - 138 分别使处于 G0/G1 期的细胞显著增加 6%和 12%，从而阻断 G1/S 期转换。用 siR - EZH2 处理对细胞功能和细胞周期无实质性影响。因此，通过计算机分析确定了参与细胞周期调节的其他靶基因。miR - 26a 显著降低其靶标 CCNE1、CCNE2 和 CDK6 的表达，而 CCND1、CCND3 和 CDK6 则被其调节因子 miR - 138 抑制。
本研究结果表明，miR - 26a 和 miR - 138 在 PCa 中具有抗增殖作用，通过阻断 G1/S 期转换，独立于 EZH2，但通过协同抑制关键的细胞周期调节因子来实现。
