Department of Urology and Helen-Diller Comprehensive Cancer Center, University of California San Francisco, San Francisco, CA, USA.
Nucleic Acid Ther. 2012 Oct;22(5):335-43. doi: 10.1089/nat.2012.0354. Epub 2012 Aug 21.
RNA activation (RNAa) is a mechanism of gene activation triggered by promoter-targeted small double-stranded RNA (dsRNA), also known as small activating RNA (saRNA). p21(WAF1/CIP1) (p21) is a putative tumor suppressor gene due to its role as a key negative regulator of the cell cycle and cell proliferation. It is frequently downregulated in cancer including hepatocellular carcinoma (HCC), but is rarely mutated or deleted, making it an ideal target for RNAa-based overexpression to restore its tumor suppressor function. In the present study, we investigated the antigrowth effects of p21 RNAa in HCC cells. Transfection of a p21 saRNA (dsP21-322) into HepG2 and Hep3B cells significantly induced the expression of p21 at both the mRNA and protein levels, and inhibited cell proliferation and survival. Further analysis of dsP21-322 transfected cells revealed that dsP21-322 arrested the cell cycle at the G(0)/G(1) phase in HepG2 cells but at G(2)/M phase in Hep3B cells which lack functional p53 and Rb genes, and induced both early and late stage apoptosis by activating caspase 3 in both cell lines. These results demonstrated that RNAa of p21 has in vitro antigrowth effects on HCC cells via impeding cell cycle progression and inducing apoptotic cell death. This study suggests that targeted activation of p21 by RNAa may be explored as a novel therapy for the treatment of HCC.
RNA 激活 (RNAa) 是一种由启动子靶向的小双链 RNA（dsRNA）触发的基因激活机制，也称为小激活 RNA（saRNA）。p21(WAF1/CIP1)（p21）是一种潜在的肿瘤抑制基因，因为它作为细胞周期和细胞增殖的关键负调节剂发挥作用。它在包括肝细胞癌（HCC）在内的癌症中经常下调，但很少发生突变或缺失，使其成为基于 RNAa 的过表达以恢复其肿瘤抑制功能的理想靶标。在本研究中，我们研究了 p21 RNAa 在 HCC 细胞中的抗增殖作用。将 p21 saRNA（dsP21-322）转染到 HepG2 和 Hep3B 细胞中，显著诱导 p21 在 mRNA 和蛋白水平的表达，并抑制细胞增殖和存活。对转染 dsP21-322 的细胞进行进一步分析表明，dsP21-322 将细胞周期阻滞在 HepG2 细胞的 G(0)/G(1)期，但在缺乏功能性 p53 和 Rb 基因的 Hep3B 细胞中阻滞在 G(2)/M 期，并通过激活 caspase 3 在两种细胞系中诱导早期和晚期凋亡。这些结果表明，p21 的 RNAa 通过阻碍细胞周期进程和诱导细胞凋亡在体外对 HCC 细胞具有抗增殖作用。本研究表明，通过 RNAa 靶向激活 p21 可能被探索为治疗 HCC 的一种新疗法。
