Proteasome inhibitors induce death but activate NF-κB on endometrial carcinoma cell lines and primary culture explants
Proteasome inhibitors induce death but activate NF-κB on endometrial carcinoma cell lines and primary culture explants
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DOI：
10.1074/jbc.m601350200
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发表时间：
2006-08-04
影响因子：
4.8
通讯作者：
Matias-Guiu, Xavier
中科院分区：
文献类型：
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作者：
Dolcet, Xavier;Llobet, David;Matias-Guiu, Xavier
蛋白酶体抑制剂目前被用作化疗药物，因为它们能够阻断NF-κ B，NF-κ B是在许多不同类型的人类癌症中组成型激活的转录因子。在本研究中，我们证明，蛋白酶体抑制剂诱导子宫内膜癌细胞系和原代外植体的细胞死亡，但不是阻止NF-κ B B，他们增加其转录活性。蛋白酶体抑制剂诱导IKK α/β的磷酸化、I κ B α的磷酸化和降解以及丝氨酸536上p65 NF-κ B亚基的磷酸化。蛋白酶体介导的NF-κ B活性可被I κ B α的不可降解形式或IKK α或IKK β的显性阴性形式阻断。慢病毒递送IKK α或IKK β的shRNA导致NF-κ B转录活性的阻断，并抑制p65在丝氨酸536上的磷酸化，但对I κ Ba降解没有影响。这些结果提示p65磷酸化在蛋白酶体转运蛋白诱导的NF-κ B活化中的作用。因此，p65的siRNA敲低抑制蛋白酶体转运蛋白诱导的NF-κ B转录活性。我们的研究结果表明，蛋白酶体抑制剂，包括硼替佐米，诱导子宫内膜癌细胞和原代外植体的细胞死亡。然而，它们激活NF-κ B而不是阻断其转录潜力。因此，蛋白酶体抑制剂是NF-κ B激活的阻断剂的概念应在特定的细胞类型中仔细检查。
Proteasome inhibitors are currently used as chemotherapeutic drugs because of their ability to block NF-kappa B, a transcription factor constitutively activated in many different types of human cancer. In the present study, we demonstrate that proteasome inhibitors induce cell death in endometrial carcinoma cell lines and primary explants but, instead of blocking NF-kappa B, they increase its transcriptional activity. Proteasome inhibitors induce phosphorylation of IKK alpha/beta, phosphorylation and degradation of I kappa B alpha, and phosphorylation of the p65 NF-kappa B subunit on serine 536. Proteasome inhibitor-induced NF-kappa B activity can be blocked by a non-degradable form of I kappa B alpha or dominant negative forms of either IKK alpha or IKK beta. Lentiviral delivery of shRNAs to either IKK alpha or IKK beta cause blockade of NF-kappa B transcriptional activity and inhibit phosphorylation of p65 on serine 536, but has no effect on I kappa Ba degradation. These results suggest a role for p65 phosphorylation in proteasome inhibitor-induced NF-kappa B activation. Accordingly, siRNA knockdown of p65 inhibits proteasome inhibitor-induced NF-kappa B transcriptional activity. Our results demonstrate that proteasome inhibitors, including bortezomib, induce cell death on endometrial carcinoma cells and primary explants. However, they activate NF-kappa B instead of blocking its transcriptional potential. Therefore, the concept that proteasome inhibitors are blockers of NF-kappa B activation should be carefully examined in particular cell types.