Constitutive activation of nuclear factor kappaB p50/p65 and Fra-1 and JunD is essential for deregulated interleukin 6 expression in prostate cancer.
Constitutive activation of nuclear factor kappaB p50/p65 and Fra-1 and JunD is essential for deregulated interleukin 6 expression in prostate cancer.
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发表时间：
2003-05
期刊：
影响因子：
11.2
通讯作者：
L. Zerbini;Yihong Wang;Je-Yoel Cho;T. Libermann
中科院分区：
文献类型：
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作者：
L. Zerbini;Yihong Wang;Je-Yoel Cho;T. Libermann
到目前为止，没有有效的治疗晚期雄激素非依赖性前列腺癌的患者，而雄激素消融治疗，手术和放射治疗是有效的治疗局部，雄激素依赖性肿瘤。雄激素依赖性和非依赖性前列腺癌之间差异的机制仍然难以捉摸。白细胞介素（IL）-6是一种多效性细胞因子，其在正常生理条件下的表达受到严格控制。然而，异常的组成型IL-6基因表达与前列腺癌进展和对化疗的抗性有关，并且与前列腺癌发病率和死亡率直接相关。特别引人注目的是IL-6在难治性前列腺癌中的表达大幅增加。IL-6除了作为免疫调节细胞因子的作用外，还作为前列腺癌细胞的生长和分化因子发挥作用。为了确定导致晚期前列腺癌中IL-6表达失调的分子机制，我们检测了雄激素非依赖性前列腺癌细胞中IL-6基因表达的调控元件。我们证明，与雄激素敏感的LNCaP细胞相反，雄激素不敏感的PC-3和DU 145细胞由于增强的启动子活性而表达高水平的IL-6蛋白和mRNA。IL-6启动子的去调节激活在很大程度上是由核因子（NF）-kappaB p50和p65以及激活蛋白1（AP-1）JunD和Fra-1家族成员的组合组成性激活介导的，如电泳迁移率变动分析、定点诱变和转染实验所证明的。NF-κ B和AP-1位点的突变显著降低了两种雄激素非依赖性前列腺癌细胞系中IL-6启动子的活性。此外，使用编码IkappaB α阻遏基因或显性失活JunD突变体的腺病毒载体抑制这些转录因子导致IL-6基因表达在mRNA和蛋白质水平上的强烈下调，如分别通过实时PCR和ELISA测量的。此外，IL-6基因表达的阻断导致DU 145细胞中组成性激活的信号转导子和转录激活子3信号通路的急剧抑制。我们的数据首次表明，在雄激素非依赖性前列腺癌细胞中，NF-κ B p50和p65以及AP-1 JunD和Fra-1的联合异常激活导致IL-6表达失调，这表明前列腺癌治疗干预的新的潜在切入点。
To date, no effective treatment for patients with advanced androgen-independent prostate cancer is available, whereas androgen ablation therapy, surgery, and radiation therapy are effective in treating local, androgen-dependent tumors. The mechanisms underlying the differences between androgen-dependent and -independent prostate cancer remain elusive. Interleukin (IL)-6 is a pleiotropic cytokine whose expression under normal physiological conditions is tightly controlled. However, aberrant constitutive IL-6 gene expression has been implicated in prostate cancer progression and resistance to chemotherapy and has been directly linked to prostate cancer morbidity and mortality. Particularly striking is the large increase in the expression of IL-6 in hormone-refractory prostate cancer. IL-6, in addition to its role as an immunomodulatory cytokine, functions as a growth and differentiation factor for prostate cancer cells. To determine the molecular mechanisms that lead to deregulated IL-6 expression in advanced prostate cancer, we examined the regulatory elements involved in IL-6 gene expression in androgen-independent prostate cancer cells. We demonstrate that, in contrast to the androgen-sensitive LNCaP cells, androgen-insensitive PC-3 and DU145 cells express high levels of IL-6 protein and mRNA due to enhanced promoter activity. Deregulated activation of the IL-6 promoter is for the most part mediated by a combined constitutive activation of the nuclear factor (NF)-kappaB p50 and p65 and the activator protein 1 (AP-1) JunD and Fra-1 family members as demonstrated by electrophoretic mobility shift assays, site-directed mutagenesis, and transfection experiments. Mutation of the NF-kappaB and AP-1 sites drastically reduces IL-6 promoter activity in both androgen-independent prostate cancer cell lines. Additionally, inhibition of these transcription factors using adenovirus vectors encoding either the IkappaBalpha repressor gene or a dominant negative JunD mutant leads to a strong down-regulation of IL-6 gene expression at the mRNA and protein level as measured by real-time PCR and ELISA, respectively. Furthermore, the blockade of IL-6 gene expression results in drastic inhibition of the constitutively activated signal transducers and activators of transcription 3 signaling pathway in DU145 cells. Our data demonstrate for the first time that a combined aberrant activation of NF-kappaB p50 and p65 and AP-1 JunD and Fra-1 in androgen-independent prostate cancer cells results in deregulated IL-6 expression, suggesting a novel potential entry point for therapeutic intervention in prostate cancer.