Department of Oncology, Beijing Chest Hospital, Capital Medical University and Beijing Tuberculosis and Thoracic Tumor Research Institute, Beijing, China.
Department of Oncology, Beijing Chest Hospital, Capital Medical University and Beijing Tuberculosis and Thoracic Tumor Research Institute, Beijing, China.
Biochem Biophys Res Commun. 2019 May 7;512(3):479-485. doi: 10.1016/j.bbrc.2019.03.093. Epub 2019 Mar 21.
Lung cancer is one of the leading causes of cancer-related death in developed countries. Despite decades of intensive efforts to comate this malignant disease, the prognosis of lung cancer remains unfavorable and is especially poor in advanced non-small cell lung cancer (NSCLC). However, whether and how the m6A demethylase FTO functions in lung cancer cells remain unknown. Here in the present study, we show that FTO plays an oncogenic role in human NSCLC. FTO mRNA and protein levels were overexpressed in human NSCLC tissues and cell lines, which was associated with the reduced m6A content. We next knocked down FTO expression in human lung cancer cell lines with lentivirus-mediated shRNAs and the cellular proliferation assay demonstrated that FTO loss-of-function reduced the proliferation rate of cancer cells. FTO knockdown also inhibited the colony formation ability of lung cancer cells. Importantly, our xenograft experiment showed that FTO knockdown reduced lung cancer cells growth in vivo. Mechanism analysis demonstrated that FTO decreased the m6A level and increased mRNA stability of ubiquitin-specific protease (USP7), which was relied on the demethylase activity of FTO. USP7 mRNA level was overexpressed in human lung cancer tissues and USP7 expression was positively correlated with FTO mRNA level. Genetic knockdown or pharmacological inhibition (P5091 or P22027) of USP7 reduced the proliferation rate of lung cancer cells and decreased the capacity of colony formation of lung cancer cells in vitro, whereas lung cancer cells growth inhibition by FTO knockdown is restored by overexertion of USP7. Collectively, our findings demonstrate that the m6A demethylase FTO promotes the growth of NSCLC cells by increasing the expression of USP7.
肺癌是发达国家癌症相关死亡的主要原因之一。尽管数十年来人们一直在努力治疗这种恶性疾病，但肺癌的预后仍然不佳，尤其是在晚期非小细胞肺癌（NSCLC）中。然而，FTO 是否以及如何在肺癌细胞中发挥作用仍不清楚。在本研究中，我们发现 FTO 在人非小细胞肺癌中发挥致癌作用。FTO mRNA 和蛋白水平在人非小细胞肺癌组织和细胞系中过表达，与 m6A 含量降低有关。接下来，我们使用慢病毒介导的 shRNA 敲低了人肺癌细胞系中的 FTO 表达，细胞增殖实验表明 FTO 功能丧失降低了癌细胞的增殖速率。FTO 敲低也抑制了肺癌细胞的集落形成能力。重要的是，我们的异种移植实验表明 FTO 敲低减少了肺癌细胞在体内的生长。机制分析表明，FTO 降低了泛素特异性蛋白酶 (USP7) 的 m6A 水平和 mRNA 稳定性，这依赖于 FTO 的去甲基酶活性。USP7 mRNA 水平在人肺癌组织中过表达，USP7 表达与 FTO mRNA 水平呈正相关。USP7 的遗传敲低或药理学抑制 (P5091 或 P22027) 降低了肺癌细胞的增殖速率，并降低了肺癌细胞在体外的集落形成能力，而 FTO 敲低对肺癌细胞生长的抑制作用可通过过表达 USP7 得到恢复。总之，我们的研究结果表明，m6A 去甲基酶 FTO 通过增加 USP7 的表达促进 NSCLC 细胞的生长。
