Department of Radiation Oncology, Zhongshan Hospital, Fudan University, Shanghai, China.
Department of Thoracic Surgery, Zhongshan Hospital, Fudan University, Shanghai, China.
Int J Biol Sci. 2020 Jan 30;16(6):1010-1022. doi: 10.7150/ijbs.40173. eCollection 2020.
Radiotherapy is an effective approach for the treatment of lung adenocarcinoma. However, evidence suggests that lung adenocarcinoma can easily develop tolerance to radiotherapy. The purpose of this study was to investigate the effect and mechanism of SMAD3 on the radiosensitivity of lung adenocarcinoma and . We found that knockdown of SMAD3 using two short hairpin RNAs in lentivirus vectors significantly inhibited cell growth and increased radiosensitivity of the lung adenocarcinoma cell lines A549, H1299, and H1975. Using RNA sequencing and bioinformatics analyses, we found that the significantly differentially expressed genes in SMAD3 knockdown cells were mainly enriched in the cell cycle process. We then showed that knockdown of SMAD3 significantly reduced expression of cyclin-dependent kinase inhibitor 1 (p21) and increased the proportion of G2/M phase cells and the radiosensitivity of lung adenocarcinoma. Chromatin immunoprecipitation results in the Gene Expression Omnibus (GEO) database and our luciferase assay verified that SMAD3 directly bound the p21 promoter. A series of rescue experiments showed that overexpression of p21 partly reversed the effect of SMAD3 on proliferation and radioresistance and . Moreover, we found that the expression levels of SMAD3 and p21 were highly correlated, and both correlated with the patients' survival in online databases and clinical specimens. Expression of SMAD3 and p21 was also significantly different between radioresistant and radiosensitive patients in our hospital. Our results indicate that SMAD3 is a potential prognosis and radiosensitivity indicator as well as a target for radiotherapy and other treatments of patients with lung adenocarcinoma.
放射治疗是治疗肺腺癌的有效方法。然而，有证据表明，肺腺癌很容易对放射治疗产生耐受性。本研究旨在探讨 SMAD3 对肺腺癌放射敏感性的影响及其机制。我们发现，使用慢病毒载体中的两个短发夹 RNA 敲低 SMAD3 显著抑制了肺腺癌细胞系 A549、H1299 和 H1975 的细胞生长并提高了其放射敏感性。通过 RNA 测序和生物信息学分析，我们发现 SMAD3 敲低细胞中显著差异表达的基因主要富集在细胞周期过程中。随后我们表明，SMAD3 的敲低显著降低了细胞周期蛋白依赖性激酶抑制剂 1（p21）的表达，增加了 G2/M 期细胞的比例，并提高了肺腺癌的放射敏感性。基因表达综合数据库（GEO）中的染色质免疫沉淀结果和我们的荧光素酶检测实验验证了 SMAD3 可直接结合 p21 启动子。一系列挽救实验表明，p21 的过表达部分逆转了 SMAD3 对增殖和放射抵抗的影响。此外，我们发现 SMAD3 和 p21 的表达水平高度相关，且在在线数据库和临床标本中均与患者的生存相关。在我们医院的研究中，我们还发现，SMAD3 和 p21 的表达在放射抵抗和放射敏感患者之间存在显著差异。我们的研究结果表明，SMAD3 是肺腺癌患者的一种潜在预后和放射敏感性指标，也是放射治疗和其他治疗的靶点。
