Cell Signal Unit, Okinawa Institute of Science and Technology Graduate University, Onna-son, Okinawa, Japan.
Laboratory of Metabolism, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.
Oncogene. 2019 Apr;38(14):2580-2594. doi: 10.1038/s41388-018-0603-7. Epub 2018 Dec 10.
Lung cancer is one of the major causes of cancer death and clarification of its molecular pathology is highly prioritized. The physiological importance of mRNA degradation through the CCR4-NOT deadenylase has recently been highlighted. For example, mutation in CNOT3, a gene coding for CNOT3 subunit of the CCR4-NOT complex, is found to be associated with T-cell acute lymphoblastic leukemia, T-ALL, though its contribution to other cancers has not been reported. Here, we provide evidence suggesting that CNOT3 is required for the growth of non-small cell lung cancer. Depletion of CNOT3 suppresses proliferation of A549 human non-small cell lung cancer cells with enhanced mRNA stability and subsequent elevated expression of p21. In addition, we identified the mRNA for Krüppel-like factor 2 transcription factor, an inducer of p21, as a novel mRNA degradation target of CNOT3 in non-small cell lung cancer cells. Aberrant up-regulation of Krüppel-like factor 2 by CNOT3 depletion leads to impairment in the proliferation of A549 cells. Consistent with these findings, elevated mRNA expression of CNOT3 in non-small cell lung cancer in comparison with the paired normal lung epithelium was confirmed through scrutinization of the RNA-sequencing datasets from The Cancer Genome Atlas. Moreover, we found an inverse correlation between CNOT3 and CDKN1A (encoding p21) mRNA expression using the combined datasets of normal lung epithelium and non-small cell lung cancer. Thus, we propose that the up-regulation of CNOT3 facilitates the development of non-small cell lung cancer through down-regulation of Krüppel-like factor 2 and p21, contrary to tumor suppressive functions of CNOT3 in T-ALL.
肺癌是癌症死亡的主要原因之一，阐明其分子病理学具有高度优先级。最近，通过 CCR4-NOT 脱腺苷酸酶进行 mRNA 降解的生理重要性已得到强调。例如，CCR4-NOT 复合物的 CNOT3 亚基编码基因 CNOT3 的突变与 T 细胞急性淋巴细胞白血病（T-ALL）有关，尽管其对其他癌症的贡献尚未报道。在这里，我们提供的证据表明 CNOT3 是非小细胞肺癌生长所必需的。CNOT3 的耗竭抑制了 A549 人非小细胞肺癌细胞的增殖，同时增强了 mRNA 的稳定性，并随后上调了 p21 的表达。此外，我们鉴定了 Krüppel 样因子 2 转录因子的 mRNA，即 p21 的诱导剂，作为非小细胞肺癌细胞中 CNOT3 的一种新型 mRNA 降解靶标。CNOT3 耗竭导致 Krüppel 样因子 2 的异常上调，从而损害 A549 细胞的增殖。通过仔细研究癌症基因组图谱中的 RNA 测序数据集，证实了与配对正常肺上皮相比，非小细胞肺癌中 CNOT3 的 mRNA 表达升高。此外，我们使用正常肺上皮和非小细胞肺癌的组合数据集发现 CNOT3 和 CDKN1A（编码 p21）mRNA 表达之间存在负相关。因此，我们提出 CNOT3 的上调通过下调 Krüppel 样因子 2 和 p21 促进非小细胞肺癌的发展，与 CNOT3 在 T-ALL 中的肿瘤抑制功能相反。
