Functional Role of Asparaginyl Endopeptidase Ubiquitination by TRAF6 in Tumor Invasion and Metastasis
Functional Role of Asparaginyl Endopeptidase Ubiquitination by TRAF6 in Tumor Invasion and Metastasis
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TRAF6 天冬酰胺酰内肽酶泛素化在肿瘤侵袭和转移中的功能作用
DOI：
10.1093/jnci/dju012
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发表时间：
2014-04-01
影响因子：
10.3
通讯作者：
Guo, Fang
中科院分区：
文献类型：
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作者：
Lin, Yingying;Qiu, Yongming;Guo, Fang
背景天冬酰胺酰内肽酶（AEP）与人类癌症的发生有关。然而，AEP调节的分子机制，包括前AEP激活的作用，仍然hailey.Methods我们研究了AEP的TRAF 6和它的调节肿瘤的进展和转移的癌细胞系，小鼠模型，和患者标本使用生化分析，共聚焦显微镜，免疫电镜，和迁移-侵袭测定的影响。通过酶联免疫吸附试验检测健康供体和乳腺癌患者的血清，并通过免疫组化评估314例乳腺癌标本的组织阵列中的AEP和TRAF 6。此外，在小鼠模型中评估AEP抑制剂或单克隆抗体对肺转移的作用。使用双尾学生t tests.Results组间的统计学意义，我们证明，TRAF 6泛素化的AEP通过K63连接的聚泛素，可逆的USP 17的前体，并形成一个复杂的HSP 90 α，随后促进前AEP细胞内的稳定性以及分泌。破坏pro-AEP和TRAF 6之间的相互作用或抑制HSP 90 alpha可以减少pro-AEP的分泌，从而减少肿瘤转移。在乳腺癌患者血清中检测到较高的循环AEP水平，并且AEP抑制剂或中和抗体在小鼠模型中显著降低肿瘤转移。值得注意的是，TRAF 6和AEP在人类乳腺肿瘤中过表达，并且与不良预后相关。AEP/TRAF 6低表达的患者平均存活111个月（95%置信区间[CI] = 108至115个月），而AEP/TRAF 6高表达的患者平均存活时间仅为61个月。（95% CI = 42至79个月;结论我们的研究阐明了乳腺癌中AEP调节的新机制和TRAF 6的另一种致癌途径，这表明AEP和TRAF 6蛋白水平可能对乳腺癌患者的预后有影响。因此，AEP可作为生物标志物以及新的治疗靶点。
Background Asparaginyl endopeptidase (AEP) has been implicated in human cancer development. However, the molecular mechanisms underlying AEP regulation, including the role of pro-AEP activation, remain elusive.Methods We investigated the regulation of AEP by TRAF6 and its effects on tumor progression and metastasis in cancer cell lines, murine models, and specimens from patients using biochemical analyses, confocal microscopy, immunoelectron microscopy, and migration-invasion assays. The sera of healthy donors and breast cancer patients were examined by enzyme-linked immunosorbent assay, and a tissue array of 314 breast cancer specimens was assessed for AEP and TRAF6 by immunohistochemistry. Furthermore, the effects of AEP inhibitors or monoclonal antibodies on pulmonary metastasis were evaluated in murine models. The statistical significance between groups was determined using two-tailed Student t tests.Results We demonstrate that TRAF6 ubiquitinates the proform of AEP through K63-linked polyubiquitin, reversible by USP17, and forms a complex with HSP90 alpha to subsequently promote pro-AEP intracellular stability as well as secretion. Disrupting the interaction between pro-AEP and TRAF6 or inhibiting HSP90 alpha reduced pro-AEP secretion and consequently reduced tumor metastasis. Higher circulating AEP levels were detected in the sera of breast cancer patients, and AEP inhibitors or neutralizing antibodies remarkably decreased tumor metastasis in murine models. Notably, TRAF6 and AEP were overexpressed in human breast neoplasms and correlated with poor prognosis. Patients with low AEP/TRAF6 expression survived for a mean of 111 months (95% confidence interval [CI] = 108 to 115 months), whereas those with high AEP/TRAF6 expression survived for a mean of only 61 months (95% CI = 42 to 79 months; P < .001).Conclusions Our study elucidates a novel mechanism of AEP regulation and an alternative oncogenic pathway for TRAF6 in breast cancer, which suggests that AEP and TRAF6 protein levels may have prognostic implications in breast cancer patients. Thus, AEP may serve as a biomarker as well as new therapeutic target.