Biomedical Experimental Laboratory, Sciences Faculty, University of Tarapaca, Arica, Chile.
Int J Mol Med. 2011 Nov;28(5):847-53. doi: 10.3892/ijmm.2011.745. Epub 2011 Jul 8.
Previous studies suggest that the effects of Egr-1 on tumorigenesis are critically dependent on the levels of Egr-1 and the cellular context. For this reason, we examined the effects of blocking the Egr-1 activity by a short interfering RNA (siRNA) against Egr-1 on the expression of nuclear factor-κB (NF-κB) and activator protein-1 (AP-1) signaling in the PC-3 and LNCaP prostate carcinoma cell lines. We observed that the reduction in expression of Egr-1 in PC-3 and LNCaP cells by effects of the siRNA vector resulted in lower cell viability and increased apoptosis at 24 and 120 h after transfection. This reduced cell viability correlated well with a reduced activity of the NF-κB and AP-1 factors. We analyzed the expression and activity of these factors and found that p65 and IκB but not p50 were reduced in the siRNA-treated cells. Similarly, we found that c-Fos but not c-Jun was reduced in the siRNA treated cells. These effects were translated to reduced transcriptional activity of NF-κB over cellular inhibitor of apoptosis (cIAP) and p21 genes, as assayed by RT-PCR and of AP-1 over a luciferase reporter activated by AP-1 response elements. Egr-1 was also found to interact directly with p65 and IκB members of the NF-κB family, thereby was able to regulate directly their activity by post-transcriptional effects. These results suggest that Egr-1 may promote prostate cancer development by modulating the activity of factors NF-κB and AP-1, which are involved in cell proliferation and apoptosis.
先前的研究表明，Egr-1 对肿瘤发生的影响取决于 Egr-1 的水平和细胞环境。因此，我们通过针对 Egr-1 的短干扰 RNA（siRNA）来检测阻断 Egr-1 活性对 PC-3 和 LNCaP 前列腺癌细胞系中核因子-κB（NF-κB）和激活蛋白-1（AP-1）信号转导的影响。我们观察到，siRNA 载体对 PC-3 和 LNCaP 细胞中 Egr-1 表达的抑制作用导致细胞活力降低，转染后 24 和 120 小时细胞凋亡增加。这种降低的细胞活力与 NF-κB 和 AP-1 因子活性的降低密切相关。我们分析了这些因子的表达和活性，发现 p65 和 IκB 而不是 p50 在 siRNA 处理的细胞中减少。同样，我们发现 c-Fos 而不是 c-Jun 在 siRNA 处理的细胞中减少。这些作用转化为 NF-κB 对细胞凋亡抑制剂（cIAP）和 p21 基因的转录活性降低，如通过 RT-PCR 检测，AP-1 对 AP-1 反应元件激活的荧光素酶报告基因的转录活性降低。Egr-1 还被发现与 NF-κB 家族的 p65 和 IκB 成员直接相互作用，从而通过转录后效应直接调节它们的活性。这些结果表明，Egr-1 可能通过调节参与细胞增殖和凋亡的 NF-κB 和 AP-1 因子的活性来促进前列腺癌的发展。
