CDK5-mediated phosphorylation and stabilization of TPX2 promotes hepatocellular tumorigenesis
CDK5-mediated phosphorylation and stabilization of TPX2 promotes hepatocellular tumorigenesis
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CDK5介导的TPX2磷酸化和稳定促进肝细胞肿瘤发生
DOI：
10.1186/s13046-019-1297-6
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发表时间：
2019-07-04
影响因子：
11.3
通讯作者：
Zhang, Jie
中科院分区：
文献类型：
--
作者：
Wang, Fuqiang;Zhao, Wenxing;Zhang, Jie
背景CDK 5是CDK家族的非典型成员，在多器官肿瘤的发生中起重要作用，但CDK 5及其底物在HCC发生发展中的作用尚不清楚。在HCC细胞系、离体异种移植物和二乙基亚硝胺诱导的HCC模型中探索CDK 5在细胞功能和肿瘤发生中的作用。此外，比较磷酸化蛋白质组学筛选确定了癌蛋白TPX 2作为CDK 5的新底物。结果CDK 5在肝癌组织中表达明显增高，且与肝癌的严重程度、复发率和5年病死率相关。外源性表达的CDK 5而非激酶死亡的CDK 5促进HCC细胞的增殖、迁移和侵袭。CDK 5的功能性消融显著抑制HCC细胞的恶化。过表达CDK 5的HCC细胞异种移植促进肿瘤发生，而CDK 5的基因敲低降低了体内HCC的生长和转移。更重要的是，杂合敲除CDK 5（Cdk 5 +/−）减弱了二乙基亚硝胺诱导的HCC肿瘤发生。CDK 5介导的TPX 2在丝氨酸486处的磷酸化促进其蛋白质稳定性。TPX 2沉默可恢复CDK 5过表达的HCC细胞迁移能力。用他莫昔芬治疗抑制细胞生长和迁移的HCC，表现出积极的CDK 5在HCC中的作用。ConclusionsOur结果表明，CDK 5的激活与HCC肿瘤发生。CDK 5介导的TPX 2磷酸化和稳定化促进肝细胞增殖和致瘤性。
BackgroundCDK5, an atypical member of the CDK family, play a significant role in the tumorigenesis of multiple organ, but CDK5 and its substrates in genesis and development of HCC is still unclear.MethodsExpression of CDK5 in HCC tumor and paired adjacent noncancerous tissues from 90 patients were measured by Western blotting, immunohistochemistry, and real-time PCR. The role of CDK5 in cell function and tumorigenesis was explored in HCC cell lines, ex vivo xenografts and diethylnitrosamine induced HCC model. Furthermore, comparative phosphoproteomic screening identified the oncoprotein TPX2 as a new substrate of CDK5. We also identified the effect of CDK5/P25 interaction blocker tamoxifen on HCC cell growth and migration.ResultsCDK5 was increased in HCC tisues and the level of CDK5 was correlated with the severity of HCC based on patient recurrence and 5-year fatality rate. Exogenously expressed CDK5 but not kinase-dead CDK5 promoted proliferation, migration, and invasion of HCC cells. Functional ablation of CDK5 significantly inhibited the exacerbation of HCC cells. Xenograft implantation of HCC cells overexpressing CDK5 promoted tumorigenesis, and genetic knockdown of CDK5 reduced HCC growth and metastasis in vivo. More importantly, heterozygous knockout CDK5 (Cdk5+/−) attenuated HCC tumorigenesis induced by diethylnitrosamine. CDK5-mediated phosphorylation of TPX2 at serine 486 promoted its protein stability. TPX2 silence could restore HCC cell migration capability with overexpression CDK5. Treatment with tamoxifen inhibited cell growth and migration of HCC, demonstrating the role of active CDK5 in HCC.ConclusionsOur results suggest activation of CDK5 is associated with HCC tumorigenesis. CDK5-mediated phosphorylation and stabilization of TPX2 promotes hepatocellular proliferation and tumorigenicity.