Department of Urology, the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.
Department of Urology, Zhejiang Provincial People's Hospital, Hangzhou, China.
Cancer Med. 2019 Sep;8(12):5716-5734. doi: 10.1002/cam4.2455. Epub 2019 Aug 7.
The aim of this study is to investigate the functions and mechanisms of miR-608 in prostate cancer (PCa). CISH and qRT-PCR analysis demonstrated that miR-608 was low expressed in PCa tissues and cells, which was partly attributed to the methylation of CpG island adjacent to the transcription start site (TSS) of miR-608 gene. Intracellular miR-608 overexpression inhibited in vivo PCa tumor growth, and suppressed PCa cell proliferation, G2/M transition, and migration in vitro, which was independent of EMT-associated mechanisms. Then RAC2, a GTPase previously deemed hematopoiesis-specific but now discovered to exist and play important roles in PCa, was verified by western blot and dual-luciferase reporter assays to mediate the effects of miR-608 through RAC2/PAK4/LIMK1/cofilin pathway. MiR-608 also promoted the apoptosis of PCa cells through BCL2L1/caspase-3 pathway by targeting the 3'-UTR of BCL2L1. Moreover, PAK4, the downstream effector of RAC2, was found to be targeted by miR-608 at the mRNA coding sequence (CDS) instead of the canonical 3'-UTR. Knocking down RAC2, PAK4, or BCL2L1 with siRNAs reproduced the antiproliferative, mitosis-obstructive, antimigratory and proapoptotic effects of miR-608 in PCa cells, which could be attenuated by downregulating miR-608. In conclusion, miR-608 suppresses PCa progression, and its activation provides a new therapeutic option for PCa.
本研究旨在探究 miR-608 在前列腺癌（PCa）中的作用和机制。CISH 和 qRT-PCR 分析表明，miR-608 在 PCa 组织和细胞中低表达，部分原因是 miR-608 基因转录起始位点（TSS）附近 CpG 岛的甲基化。细胞内 miR-608 过表达抑制体内 PCa 肿瘤生长，并抑制 PCa 细胞体外增殖、G2/M 期转换和迁移，这与 EMT 相关机制无关。然后通过 Western blot 和双荧光素酶报告基因检测验证 RAC2，一种先前被认为是造血特异性的 GTPase，但现在发现它存在于前列腺癌中并发挥重要作用，通过 RAC2/PAK4/LIMK1/cofilin 通路介导 miR-608 的作用。miR-608 还通过靶向 BCL2L1 的 3'-UTR 来促进 PCa 细胞的凋亡。此外，RAC2 的下游效应物 PAK4 被发现在 miR-608 的 mRNA 编码序列（CDS）而不是典型的 3'-UTR 上被靶向。用 siRNAs 敲低 RAC2、PAK4 或 BCL2L1 可重现 miR-608 在 PCa 细胞中的抗增殖、有丝分裂障碍、抗迁移和促凋亡作用，而下调 miR-608 可减弱这些作用。总之，miR-608 抑制 PCa 的进展，其激活为 PCa 提供了一种新的治疗选择。
