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A feedforward circuit shaped by ECT2 and USP7 contributes to breast carcinogenesis.
Theranostics ( IF 12.4 ) Pub Date : 2020-8-29 , DOI: 10.7150/thno.46878
Qi Zhang 1 , Cheng Cao 1 , Wenchen Gong 1 , Kaiwen Bao 1 , Qian Wang 1 , Yuejiao Wang 1 , Liyuan Bi 2 , Shuai Ma 1 , Jiao Zhao 1 , Ling Liu 1 , Shanshan Tian 1 , Kai Zhang 1 , Jie Yang 1 , Zhi Yao 1 , Nan Song 1 , Lei Shi 1
Affiliation  

Rationale: A number of guanine nucleotide exchange factors (GEFs) including epithelial cell transforming factor ECT2 are believed to drive carcinogenesis through activating distinct oncogenic GTPases. Yet, whether GEF-independent activity of ECT2 also plays a role in tumorigenesis remains unclear./nMethods: Immunohistochemical (IHC) staining, colony formation and xenograft assays were used to examine the role of ECT2 in breast carcinogenesis. Co-immunoprecipitation, immunofluorescent stainings, in vivo deubiquitination and in vitro deubiquitination experiments were performed to examine the physical and functional interaction between ECT2 and ubiquitin-specific protease USP7. High-throughput RNA sequencing, quantitative reverse transcription-PCR and Western blotting were employed to investigate the biological significance of the interplay between ECT2 and USP7./nResults: We report that ECT2 plays a tumor-promoting role in breast cancer, and GEF activity-deficient ECT2 is able to alleviate ECT2 depletion associated growth defects in breast cancer cells. Mechanistically, we demonstrated that ECT2 physically interacts with ubiquitin-specific protease USP7 and functionally facilitates USP7 intermolecular self-association, -deubiquitination and -stabilization in a GEF activity-independent manner. USP7 in turn, deubiquitinates and stabilizes ECT2, resulting in a feedforward regulatory circuit that ultimately sustains the expression of oncogenic protein MDM2./nConclusion: Our study uncovers a GEF-independent role of ECT2 in promoting survival of breast cancer cells, provides a molecular insight for the reciprocal regulation of ECT2 and USP7, and supports the pursuit of ECT2/USP7 as potential targets for breast cancer intervention.

中文翻译:

由ECT2和USP7形成的前馈回路有助于乳腺癌的发生。

理由:包括上皮细胞转化因子ECT2在内的许多鸟嘌呤核苷酸交换因子(GEF)被认为通过激活独特的致癌GTPases来驱动致癌作用。然而,尚不清楚ECT2的GEF依赖性活性是否在肿瘤发生中也起作用。/n方法:免疫组织化学(IHC)染色,菌落形成和异种移植测定法被用来检验ECT2在乳腺癌致癌作用中的作用。免疫共沉淀,免疫荧光染色,体内去泛素化和体外进行了脱泛素化实验以检查ECT2和泛素特异性蛋白酶USP7之间的物理和功能相互作用。高通量RNA测序,定量逆转录PCR和Western印迹被雇用来调查ECT2和USP7./n之间的相互作用的生物学意义结果:我们报告说,ECT2在乳腺癌中起到促进肿瘤的作用,而GEF活性不足的ECT2能够缓解ECT2耗竭相关的乳腺癌细胞生长缺陷。从机理上讲,我们证明了ECT2与泛素特异性蛋白酶USP7发生物理相互作用,并以与GEF活性无关的方式在功能上促进了USP7的分子间自缔合,-去泛素化和-稳定化。USP7反过来,去泛素和稳定ECT2,产生的前馈调节电路,最终维持致癌蛋白MDM2./n的表达结论: 我们的研究揭示了ECT2在促进乳腺癌细胞存活中与GEF无关的作用,为ECT2和USP7的相互调节提供了分子生物学的见解,并支持追求ECT2 / USP7作为乳腺癌干预的潜在靶标。
更新日期:2020-08-30
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