Department of Pathogenobiology, Daqing Branch of Harbin Medical University, Daqing, China.
Oncol Res. 2013;20(10):437-45. doi: 10.3727/096504013x13685487925059.
RBP-J-interacting and tubulin-associated (RITA) is a novel RBP-J-interacting protein that downregulates Notch-mediated transcription. The current study focuses on the antitumor effect of RITA in human hepatocellular carcinoma (HCC) and aims to explore its molecular mechanism. Thirty paired HCC and adjacent non-tumoral liver samples were analyzed by real-time quantitative reverse transcriptase polymerase chain reaction (qRT-PCR). RITA overexpression was induced by transfection of a pcDNA3.1-Flag-RITA plasmid into HepG2 cells. RITA knockdown was achieved by siRNA transfection. mRNA and protein expression of target genes were quantified by qRT-PCR and Western blotting, respectively. Cell proliferation and apoptosis were measured using MTT assay and flow cytometry. Our results demonstrate that adjacent nontumoral liver samples exhibited increased RITA expression compared to HCC tissues (p < 0.05); RITA levels were associated with tumor differentiation status. Overexpression of RITA suppressed cell proliferation and promoted early apoptosis, while its silencing promoted cell growth dramatically (p < 0.05). RITA overexpression upregulated p53 and reduced cyclin E levels, whereas silencing of RITA had the opposite effect on p53 and cyclin E expression. Our in vitro results represent the first evidence that RITA might suppress tumor growth and induce apoptosis in HCCs, and may be a potent antitumoral agent for HCC treatment that deserves further exploration.
RBP-J 相互作用和微管相关蛋白（RITA）是一种新型的 RBP-J 相互作用蛋白，可下调 Notch 介导的转录。本研究主要关注 RITA 在人肝癌（HCC）中的抗肿瘤作用，并旨在探讨其分子机制。通过实时定量逆转录聚合酶链反应（qRT-PCR）分析 30 对 HCC 和相邻非肿瘤性肝组织样本。通过将 pcDNA3.1-Flag-RITA 质粒转染到 HepG2 细胞中诱导 RITA 过表达。通过 siRNA 转染实现 RITA 敲低。通过 qRT-PCR 和 Western blot 分别定量测定靶基因的 mRNA 和蛋白表达。通过 MTT 测定和流式细胞术测量细胞增殖和凋亡。我们的结果表明，与 HCC 组织相比，相邻非肿瘤性肝组织样本中 RITA 表达增加（p<0.05）；RITA 水平与肿瘤分化状态有关。RITA 过表达抑制细胞增殖并促进早期凋亡，而其沉默则显著促进细胞生长（p<0.05）。RITA 过表达上调了 p53 并降低了细胞周期蛋白 E 的水平，而 RITA 沉默对 p53 和细胞周期蛋白 E 的表达则有相反的影响。我们的体外结果首次表明，RITA 可能抑制 HCC 中的肿瘤生长并诱导细胞凋亡，可能是治疗 HCC 的有效抗肿瘤药物，值得进一步探索。
