Center for Precision Environmental Health, Baylor College of Medicine, One Baylor Plaza, BCM130, Houston, TX, 77030, USA.
Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, USA.
Sci Rep. 2021 May 17;11(1):10461. doi: 10.1038/s41598-021-89933-7.
Loss of primary cilia in cells deficient for the tumor suppressor von Hippel Lindau (VHL) arise from elevated Aurora Kinase A (AURKA) levels. VHL in its role as an E3 ubiquitin ligase targets AURKA for degradation and in the absence of VHL, high levels of AURKA result in destabilization of the primary cilium. We identified NVP-BEZ235, a dual PI3K/AKT and mTOR inhibitor, in an image-based high throughput screen, as a small molecule that restored primary cilia in VHL-deficient cells. We identified the ability of AKT to modulate AURKA expression at the transcript and protein level. Independent modulation of AKT and mTOR signaling decreased AURKA expression in cells confirming AURKA as a new signaling node downstream of the PI3K cascade. Corroborating these data, a genetic knockdown of AKT in cells deficient for VHL rescued the ability of these cells to ciliate. Finally, inhibition of AKT/mTOR using NVP-BEZ235 was efficacious in reducing tumor burden in a 786-0 xenograft model of renal cell carcinoma. These data highlight a previously unappreciated signaling node downstream of the AKT/mTOR pathway via AURKA that can be targeted in VHL-null cells to restore ciliogenesis.
缺乏抑癌基因 von Hippel Lindau（VHL）的细胞中初级纤毛的丧失是由于 Aurora Kinase A（AURKA）水平升高所致。VHL 作为一种 E3 泛素连接酶，可将 AURKA 靶向降解，而在 VHL 缺失的情况下，AURKA 水平升高会导致初级纤毛不稳定。我们在基于图像的高通量筛选中发现了 NVP-BEZ235，这是一种双重 PI3K/AKT 和 mTOR 抑制剂，它可以恢复 VHL 缺陷细胞中的初级纤毛。我们发现 AKT 能够在转录和蛋白水平上调节 AURKA 的表达。AKT 和 mTOR 信号的独立调节降低了细胞中的 AURKA 表达，证实 AURKA 是 PI3K 级联下游的一个新的信号节点。这些数据得到了证实，在 VHL 缺陷细胞中敲低 AKT 的基因可挽救这些细胞的纤毛形成能力。最后，使用 NVP-BEZ235 抑制 AKT/mTOR 在肾透明细胞癌的 786-0 异种移植模型中有效减少了肿瘤负担。这些数据突出了 AKT/mTOR 通路下游以前未被认识到的通过 AURKA 的信号节点，该节点可在 VHL 缺失的细胞中被靶向以恢复纤毛发生。
