Targeting the p27 E3 ligase SCFSkp2 results in p27-and Skp2-mediated cell-cycle arrest and activation of autophagy
Targeting the p27 E3 ligase SCFSkp2 results in p27-and Skp2-mediated cell-cycle arrest and activation of autophagy
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DOI：
10.1182/blood-2007-09-112904
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发表时间：
2008-05-01
期刊：
影响因子：
20.3
通讯作者：
Orlowski, Robert Z.
中科院分区：
文献类型：
--
作者：
Chen, Qing;Xie, Weilin;Orlowski, Robert Z.
P27（KiP 1）水平降低是许多恶性肿瘤的不良预后因素，可通过上调SCFSkp 2 E3连接酶功能发生，导致p27泛素化和蛋白酶体介导的降解增强。虽然蛋白酶体抑制剂稳定P27（Kip 1），但抑制SCFSkp 2的药物可能代表更直接的靶向药物，有望提高疗效并降低毒性。使用高通量筛选，我们鉴定了化合物A（CpdA），其在体外干扰SCFSkP 2连接酶功能，并诱导细胞中p21和其他SCFSkp 2底物的特异性积累，而不激活热休克蛋白反应。CpdA阻止Skp 2掺入SCFSkp 2连接酶，并诱导G（1）/S细胞周期停滞以及SCFSkp 2和p27依赖性细胞杀伤。这种程序性细胞死亡是半胱天冬酶非依赖性的，而是通过自噬激活发生的。在多发性骨髓瘤模型中，CpdA克服了对地塞米松、多柔比星和美法仑以及硼替佐米的耐药性，并且还与这种蛋白酶体抑制剂协同作用。重要的是，CpdA对患者来源的浆细胞和髓样和淋巴母细胞样白血病母细胞都有活性，并显示出对肿瘤细胞的优先活性，同时相对保留其他骨髓成分。这些发现为进一步开发SCFSkP 2抑制剂作为一类新型抗肿瘤药物提供了合理的框架。
Decreased P27(KiP1) levels are a poor prognostic factor in many malignancies, and can occur through up-regulation of SCFSkp2 E3 ligase function, resulting in enhanced p27 ubiquitination and proteasome-mediated degradation. While proteasome inhibitors stabilize P27(Kip1), agents inhibiting SCFSkp2 may represent more directly targeted drugs with the promise of enhanced efficacy and reduced toxicity. Using high-throughput screening, we identified Compound A (CpdA), which interfered with SCFSkP2 ligase function in vitro, and induced specific accumulation of p21 and other SCFSkp2 substrates in cells without activating a heat-shock protein response. CpdA prevented incorporation of Skp2 into the SCFSkp2 ligase, and induced G(1)/S cell-cycle arrest as well as SCFSkp2- and p27-dependent cell killing. This programmed cell death was caspase-independent, and instead occurred through activation of autophagy. In models of multiple myeloma, CpdA overcame resistance to dexamethasone, doxorubicin, and melphalan, as well as to bortezomib, and also acted synergistically with this proteasome inhibitor. Importantly, CpdA was active against patient-derived plasma cells and both myeloid and lymphoblastoid leukemia blasts, and showed preferential activity against neoplastic cells while relatively sparing other marrow components. These findings provide a rational framework for further development of SCFSkP2 inhibitors as a novel class of antitumor agents.