Nelson Institute of Environmental Medicine, New York University, School of Medicine, New York, New York.
Department of Pediatrics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
Mol Carcinog. 2019 May;58(5):777-793. doi: 10.1002/mc.22970. Epub 2019 Jan 29.
Although overexpression of the non-canonical NFκB subunit p52 has been observed in several tumors, the function and mechanism of p52 in bladder cancer (BC) are less well understood. Here, we aimed at understanding the role and mechanism underlying p52 regulation of BC invasion. Human p52 was stably knockdown with shRNA targeting p52 in two bladder cancer cell lines (T24 and UMUC3). Two constitutively expressing constructs, p52 and p100, were stably transfected in to T24 or UMUC3, respectively. The stable transfectants were used to determine function and mechanisms responsible for p52 regulation of BC invasion. We demonstrate that p52 mediates human BC invasion. Knockdown of p52 impaired bladder cancer invasion by reduction of rhogdiβ mRNA stability and expression. Positively regulation of rhogdiβ mRNA stability was mediated by p52 promoting AUF1 protein degradation, consequently resulting in reduction of AUF1 binding to rhogdiβ mRNA. Further studies indicated that AUF1 protein degradation was mediated by upregulating USP8 transcription, which was modulated by its negative regulatory transcription factor Sp1. Moreover, we found that p52 upregulated miR-145, which directly bound to the 3'-UTR of sp1 mRNA, leading to downregulation of Sp1 protein translation. Our results reveal a comprehensive pathway that p52 acts as a positive regulator of BC invasion by initiating a novel miR-145/Sp1/USP8/AUF1/RhoGDIβ axis. These findings provide insight into the understanding of p52 in the pathology of human BC invasion and progression, which may be useful information in the development of preventive and therapeutic approaches for using p52 as a potential target.
虽然在几种肿瘤中观察到非典型 NFκB 亚基 p52 的过表达，但 p52 在膀胱癌 (BC) 中的功能和机制了解较少。在这里，我们旨在了解 p52 调节 BC 侵袭的作用和机制。使用针对 p52 的 shRNA 在两种膀胱癌细胞系 (T24 和 UMUC3) 中稳定敲低人 p52。将两个组成型表达构建体 p52 和 p100 分别稳定转染到 T24 或 UMUC3 中。使用稳定转染子来确定负责 p52 调节 BC 侵袭的功能和机制。我们证明 p52 介导人 BC 侵袭。通过降低 rhogdiβ mRNA 稳定性和表达，p52 的敲低削弱了膀胱癌的侵袭能力。rhogdiβ mRNA 稳定性的正向调节是通过 p52 促进 AUF1 蛋白降解介导的，这导致 AUF1 与 rhogdiβ mRNA 的结合减少。进一步的研究表明，AUF1 蛋白降解是通过上调 USP8 转录介导的，USP8 转录受其负调控转录因子 Sp1 调节。此外，我们发现 p52 上调了 miR-145，miR-145 直接与 sp1 mRNA 的 3'-UTR 结合，导致 Sp1 蛋白翻译下调。我们的研究结果揭示了一个全面的途径，即 p52 通过启动一个新的 miR-145/Sp1/USP8/AUF1/RhoGDIβ 轴，作为 BC 侵袭的正调节剂。这些发现为理解 p52 在人类 BC 侵袭和进展的病理学中的作用提供了深入的了解，这可能为使用 p52 作为潜在靶点开发预防和治疗方法提供有用的信息。
