Kukreja Promil, Abdel-Mageed Asim B, Mondal Debasis, Liu Kai, Agrawal Krishna C
Department of Pharmacology, Tulane University Health Sciences Center, New Orleans, Louisiana 70112, USA.
Cancer Res. 2005 Nov 1;65(21):9891-8. doi: 10.1158/0008-5472.CAN-05-1293.
The chemokine stromal-derived factor-1alpha (SDF-1alpha/CXCL-12) and its receptor, CXCR4, play a crucial role in adhesion and transendothelium migration (TEM) of prostate cancer cells. We tested the hypothesis that enhanced expression of CXCR4 in prostate cancer cells is dependent upon SDF-1alpha-mediated activation of nuclear factor-kappaB (NF-kappaB). SDF-1alpha increased the CXCR4 mRNA and protein expression in PC-3 cells but not in LNCaP cells. Similarly, SDF-1alpha enhanced the NF-kappaB-dependent transcriptional activity in PC-3 cells but not in LNCaP cells. SDF-1alpha increased PC-3 cell adhesion to the human umbilical vein endothelial cell monolayer and enhanced TEM, which was abrogated with anti-CXCR4 monoclonal antibody (mAb). Suppression of NF-kappaB activity in PC-3 cells by a mutant IkappaBalpha super-repressor adenoviral vector decreased the CXCR4 mRNA expression and inhibited adhesion and TEM. Transient overexpression of p65 subunit of NF-kappaB in PC-3 cells up-regulated CXCR4 receptor expression and increased the adhesion and TEM of these cells in response to SDF-1alpha gradient. Treatment of PC-3 cells with SDF-1alpha leads to nuclear translocation of NF-kappaB protein within 15 to 30 minutes, which correlated with IkappaBalpha phosphorylation. A p42/44 mitogen-activated protein kinase [MAPK, extracellular signal regulated kinase-1/2 (ERK-1/2)] biphasic activation pattern was observed in these cells at 15 minutes and 3 hours after SDF-1alpha treatment. Phosphorylation of IkappaB kinase alpha was observed within 30 minutes, which was blocked by PD98059 [MAPK kinase (MEK) inhibitor]. PD98059 cotreatment significantly inhibited SDF-1alpha-induced NF-kappaB reporter activity and CXCR4 receptor expression as shown by flow cytometry. These data suggest that SDF-1alpha-induced expression of CXCR4 in PC-3 cells is dependent on MEK/ERK signaling cascade and NF-kappaB activation.
趋化因子基质细胞衍生因子-1α（SDF-1α/CXCL-12）及其受体CXCR4在前列腺癌细胞的黏附及跨内皮迁移（TEM）过程中发挥着关键作用。我们验证了如下假说：前列腺癌细胞中CXCR4表达的增强依赖于SDF-1α介导的核因子-κB（NF-κB）激活。SDF-1α可增加PC-3细胞中CXCR4的mRNA及蛋白表达，但对LNCaP细胞无此作用。同样，SDF-1α可增强PC-3细胞中NF-κB依赖的转录活性，而对LNCaP细胞无此作用。SDF-1α增加了PC-3细胞对人脐静脉内皮细胞单层的黏附，并增强了TEM，抗CXCR4单克隆抗体（mAb）可消除这种作用。用突变型IκBα超级阻遏物腺病毒载体抑制PC-3细胞中的NF-κB活性，可降低CXCR4 mRNA表达，并抑制黏附及TEM。在PC-3细胞中瞬时过表达NF-κB的p65亚基，可上调CXCR4受体表达，并增加这些细胞在SDF-1α梯度作用下的黏附及TEM。用SDF-1α处理PC-3细胞可导致NF-κB蛋白在15至30分钟内发生核转位，这与IκBα磷酸化相关。在SDF-1α处理后的15分钟和3小时，这些细胞中观察到p42/44丝裂原活化蛋白激酶[MAPK，细胞外信号调节激酶-1/2（ERK-1/2）]呈现双相激活模式。在30分钟内观察到IκB激酶α的磷酸化，其被PD[98059 MAPK激酶（MEK）抑制剂]阻断。如流式细胞术所示，PD98059联合处理显著抑制了SDF-1α诱导的NF-κB报告基因活性及CXCR4受体表达。这些数据表明，SDF-1α诱导PC-3细胞中CXCR4的表达依赖于MEK/ERK信号级联反应及NF-κB激活。
