The Key Laboratory of Experimental Teratology, Ministry of Education and Department of Pathology, Shandong University QiLu Medical College, School of Basic Medical Sciences, Jinan, China.
Department of Pathology, Binzhou Medical University, Binzhou, China.
Prostate. 2019 Apr;79(5):480-488. doi: 10.1002/pros.23754. Epub 2019 Jan 4.
Cullin 4B (CUL4B), a scaffold protein that assembles CRL4B ubiquitin ligase complexes, is overexpressed in many types of solid tumors and contributes to epigenetic silencing of tumor suppressors. However, its clinical significance and underlying molecular mechanisms in prostate cancer (PCa) remain unknown.
The clinical significance of CUL4B in PCa was characterized by in silico method. RT-qPCR and Western blot were used to study the transcript and protein expression levels of CUL4B and C-MYC. Bioinformatics tools, chromatin immunoprecipitation (ChIP) and luciferase reporter assay were utilized to identify and characterize the microRNAs (miRNAs) regulated by CUL4B. The biological function of CUL4B and miR-33b-5p was evaluated by MTS, transwell, and wound healing assays, accordingly.
CUL4B is significantly overexpressed in PCa tissues compared with benign prostatic tissues and its overexpression is correlated with poor prognosis. CUL4B promotes proliferation and aggressiveness of PCa cells in vitro. Mechanistically, we demonstrate that CUL4B upregulates the expression of C-MYC at post-transcriptional level through epigenetic silencing of miR-33b-5p. Importantly, CUL4B-induced oncogenic activity in PCa by targeting C-MYC is repressed by miR-33b-5p.
Our results suggested a novel CUL4B/miR-33b/C-MYC axis implicated in PCa cell growth and progression. This might provide novel insight into how CUL4B contributed to PCa aggressiveness and progression.
Cullin 4B（CUL4B）是一种组装 CRL4B 泛素连接酶复合物的支架蛋白，在许多实体瘤中过表达，并有助于肿瘤抑制因子的表观遗传沉默。然而，其在前列腺癌（PCa）中的临床意义和潜在分子机制尚不清楚。
通过计算机方法研究 CUL4B 在 PCa 中的临床意义。采用 RT-qPCR 和 Western blot 检测 CUL4B 和 C-MYC 的转录本和蛋白表达水平。利用生物信息学工具、染色质免疫沉淀（ChIP）和荧光素酶报告基因检测来鉴定和表征受 CUL4B 调控的 microRNAs（miRNAs）。通过 MTS、transwell 和划痕愈合实验评估 CUL4B 和 miR-33b-5p 的生物学功能。
与良性前列腺组织相比，CUL4B 在 PCa 组织中显著过表达，其过表达与预后不良相关。CUL4B 在体外促进 PCa 细胞的增殖和侵袭能力。机制上，我们证明 CUL4B 通过表观遗传沉默 miR-33b-5p 在上转录后水平上调 C-MYC 的表达。重要的是，miR-33b-5p 可抑制 CUL4B 通过靶向 C-MYC 诱导的 PCa 致癌活性。
我们的研究结果表明，CUL4B/miR-33b/C-MYC 轴在 PCa 细胞生长和进展中发挥作用。这可能为 CUL4B 如何促进 PCa 的侵袭性和进展提供新的见解。
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