Cancer Center, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China.
Department of Thoracic Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China.
Theranostics. 2018 Jan 1;8(3):650-662. doi: 10.7150/thno.21963. eCollection 2018.
Radioresistance is considered the main cause of local relapse in lung cancer. However, the molecular mechanisms of radioresistance remain poorly understood. This study investigates the role of CDK16 in radioresistance of human lung cancer cells. The expression levels of CDK16 were determined by immunohistochemistry in lung cancer tissues and adjacent normal lung tissues. Immunoprecipitation assay and GST pulldown were utilized to detect the protein-protein interaction. The phosphorylation of p53 was evaluated by kinase assay. Poly-ubiquitination of p53 was examined by ubiquitination assay. Cell growth and apoptosis, ROS levels and DNA damage response were measured for functional analyses. We showed that CDK16 is frequently overexpressed in lung cancer cells and tissues, and high levels of CDK16 are correlated with lymph node stage and poor prognosis in lung cancer patients. Furthermore, we provided evidence that CDK16 binds to and phosphorylates p53 at Ser315 site to inhibit transcriptional activity of p53. Moreover, we uncovered that this phosphorylation modification accelerates p53 degradation via the ubiquitin/proteasome pathway. Importantly, we demonstrated that CDK16 promotes radioresistance by suppressing apoptosis and ROS production as well as inhibiting DNA damage response in lung cancer cells in a p53-dependent manner. Our findings suggest that CDK16 negatively modulates p53 signaling pathway to promote radioresistance, and therefore represents a promising therapeutic target for lung cancer radiotherapy.
放射抵抗被认为是肺癌局部复发的主要原因。然而，放射抵抗的分子机制仍知之甚少。本研究探讨了 CDK16 在人肺癌细胞放射抵抗中的作用。通过免疫组化法检测肺癌组织和相邻正常肺组织中 CDK16 的表达水平。免疫沉淀和 GST 下拉实验用于检测蛋白-蛋白相互作用。激酶实验评估 p53 的磷酸化水平。泛素化实验检测 p53 的多聚泛素化。进行细胞生长和凋亡、ROS 水平和 DNA 损伤反应的功能分析。我们发现 CDK16 在肺癌细胞和组织中频繁过表达，并且 CDK16 高水平与肺癌患者的淋巴结分期和预后不良相关。此外，我们提供了证据表明 CDK16 结合并磷酸化 p53 上的 Ser315 位点，从而抑制 p53 的转录活性。此外，我们发现这种磷酸化修饰通过泛素/蛋白酶体途径加速 p53 的降解。重要的是，我们证明 CDK16 通过抑制肺癌细胞中的凋亡和 ROS 产生以及抑制 DNA 损伤反应，以依赖 p53 的方式促进放射抵抗。我们的研究结果表明，CDK16 负调控 p53 信号通路以促进放射抵抗，因此代表了肺癌放疗的一个有前途的治疗靶点。
