ABSTRACT

Ubiquitin-specific protease 33 (USP33), a deubiquitinating enzyme (DUB), has been identified to serve as a tumor suppressor or an oncogene in different cancers. However, its role in retinoblastoma (RB) remains unknown. Here, we aimed to uncover USP33 expression profile and function in RB, and disclose the underlying mechanism. USP33 levels in RB tissues and cells were determined using RT-qPCR and western blotting assays. USP33 effects on cell growth, cycle, apoptosis and tumorigenesis were studied using MTT, Edu, cycle and western blotting and in vivo assays. The results showed that USP33 expression levels were elevated in RB tissues and cells as compared with normal retinal tissues and cells. Downregulation of USP33 in RB Y79 and WERI-RB1 cells leaded to significant increases in cell apoptosis, G1 phase arrest and tumorigenesis, and reductions in cell growth and G2 and S phase arrest, as well as inhibited the activation of the PI3K/AKT signaling. SP1 overexpression abolished the roles of USP33 downregulation in modulating the activation of PI3K/AKT signaling, cell growth, apoptosis, and cell cycle. This study uncovered that USP33 promoted the progression of RB through regulation of the SP1/PI3K/AKT pathway.

摘要

泛素特异性蛋白酶 33 (USP33) 是一种去泛素化酶 (DUB)，已被确定为不同癌症中的肿瘤抑制因子或癌基因。然而，它在视网膜母细胞瘤 (RB) 中的作用仍然未知。在这里，我们旨在揭示 RB 中的 USP33 表达谱和功能，并揭示其潜在机制。使用 RT-qPCR 和蛋白质印迹测定法测定 RB 组织和细胞中的 USP33 水平。使用 MTT、Edu、循环和蛋白质印迹以及在体内研究了 USP33 对细胞生长、周期、细胞凋亡和肿瘤发生的影响化验。结果表明，与正常视网膜组织和细胞相比，RB组织和细胞中USP33的表达水平升高。RB Y79 和 WERI-RB1 细胞中 USP33 的下调导致细胞凋亡、G1 期阻滞和肿瘤发生的显着增加，以及细胞生长和 G2 和 S 期阻滞的减少，以及抑制 PI3K/AKT 信号传导的激活。SP1 过表达消除了 USP33 下调在调节 PI3K/AKT 信号通路激活、细胞生长、细胞凋亡和细胞周期中的作用。本研究发现 USP33 通过调节 SP1/PI3K/AKT 通路促进 RB 的进展。