A novel NF-κB-inducing kinase-MAPK signaling pathway up-regulates NF-κB activity in melanoma cells
A novel NF-κB-inducing kinase-MAPK signaling pathway up-regulates NF-κB activity in melanoma cells
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DOI：
10.1074/jbc.m112210200
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发表时间：
2002-03-08
影响因子：
4.8
通讯作者：
Richmond, A
中科院分区：
文献类型：
--
作者：
Dhawan, P;Richmond, A
NF-κ B的组成性激活是包括乳腺癌、结肠癌、胰腺癌、卵巢癌和黑色素瘤在内的各种类型肿瘤的新标志。在黑色素瘤细胞中，CXC趋化因子CXCL1的基础表达是组成性上调的。这种上调可以部分归因于NF-κ B的组成性激活。先前的研究表明，在Hs294T黑色素瘤细胞中，基础IkappaB激酶（IKK）活性升高，这导致IkappaB磷酸化和降解速率增加。IkappaB-α磷酸化和降解的增加导致NF-κ B的核定位增加了19倍。然而，上游IKK激酶活性仅上调约2倍，不能解释观察到的NF-κ B活性增加。我们现在证明，NF-κ B诱导激酶（NIK）在黑色素瘤细胞中高度表达，与正常细胞相比，这些细胞中IKK相关的NIK活性增强。激酶死亡的NIK阻断了Hs294T黑色素瘤细胞中的组成型NF-κ B或CXCL 1启动子活性，但在对照正常人表皮黑色素细胞中没有。野生型NIK的瞬时过表达导致细胞外信号调节激酶1和2（ERK 1/2）的磷酸化增加，其以浓度依赖性方式被p42/44 MAPK抑制剂PD98059抑制。此外，NF-kappaB启动子活性随着显性负性ERK表达构建体的过表达而降低，EMSA分析进一步支持ERK作用于NF-kappaB上游并调节NF-kappaB DNA结合活性的假设。综上所述，我们的数据暗示了IkappaB激酶和MAPK信号级联参与了NIK诱导的NF-κ B的组成性激活。
Constitutive activation of NF-kappaB is an emerging hallmark of various types of tumors including breast, colon, pancreatic, ovarian, and melanoma. In melanoma cells, the basal expression of the CXC chemokine, CXCL1, is constitutively up-regulated. This up-regulation can be attributed in part to constitutive activation of NF-kappaB. Previous studies have shown an elevated basal IkappaB kinase (IKK) activity in Hs294T melanoma cells, which leads to an increased rate of IkappaB phosphorylation and degradation. This increase in IkappaB-alpha phosphorylation and degradation leads to an similar to19-fold higher nuclear localization of NF-kappaB. However, the upstream IKK kinase activity is up-regulated by only about 2-fold and cannot account for the observed increase in NF-kappaB activity. We now demonstrate that NF-kappaB-inducing kinase (NIK) is highly expressed in melanoma cells, and IKK-associated NIK activity is enhanced in these cells compared with the normal cells. Kinase-dead NIK blocked constitutive NF-kappaB or CXCL1 promoter activity in Hs294T melanoma cells, but not in control normal human epidermal melanocytes. Transient overexpression of wild type NIK results in increased phosphorylation of extracellular signal-regulated kinases 1 and 2 (ERK1/2), which is inhibited in a concentration-dependent manner by PD98059, an inhibitor of p42/44 MAPK. Moreover, the NF-kappaB promoter activity decreased with overexpression of dominant negative ERK expression constructs, and EMSA analyses further support the hypothesis that ERK acts upstream of NF-kappaB and regulates the NF-kappaB DNA binding activity. Taken together, our data implicate involvement of IkappaB kinase and MAPK signaling cascades in NIK-induced constitutive activation of NF-kappaB.