Veeranki Omkara Lakshmi, Tong Zhimin, Dokey Rashmi, Mejia Alicia, Zhang Jianhu, Qiao Yawei, Singh Pankaj Kumar, Katkhuda Riham, Mino Barbara, Tailor Ramesh, Canales Jaime Rodriguez, Bassett Roland, Ajani Jaffer, Wu Ji Yuan, Kopetz Scott, Blum Mariela, Hofstetter Wayne, Tetzlaff Michael, Krishnan Sunil, Lin Steven H, Maru Dipen
Department of Pathology, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA.
Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA.
Oncotarget. 2019 Jul 23;10(45):4703-4718. doi: 10.18632/oncotarget.27095.
Cyclin-dependent kinase 9 (CDK9) transcriptionally regulates several proteins and cellular pathways central to radiation induced tissue injury. We investigated a role of BAY1143572, a new highly specific CDK9 inhibitor, as a sensitizer to radiation in esophageal adenocarcinoma. synergy between the CDK9 inhibitor and radiation was evaluated by clonogenic assay. synergy between the CDK9 inhibitor and radiation was assessed in multiple xenograft models including a patient's tumor derived xenograft (PDX). Reverse phase protein array (RPPA), western blotting, immunohistochemistry, and qPCR were utilized to identify and validate targets of the CDK9 inhibitor. The CDK9 inhibitor plus radiation significantly reduced growth of FLO-1, SKGT4, OE33, and radiation resistant OE33R xenografts and PDXs as compared to the cohorts treated with either single agent CDK9 inhibitor or radiation alone. RPPA identified Axl as a candidate target of CDK9 inhibition. Western blot and qPCR demonstrated reduced Axl mRNA ( = 0.02) and protein levels after treatment with CDK9 inhibitor with or without radiation in FLO-1 and SKGT4 cells. Axl protein expression in FLO-1 xenografts treated with combination of CDK9 inhibitor and radiation was significantly lower than the xenografts treated with radiation alone ( = 0.003). Clonogenic assay performed after overexpression of Axl in FLO-1 and SKGT4 cells enhanced radiosensitization by the CDK9 inhibitor, suggesting dependency of radiosensitization effects of the CDK9 inhibitor on Axl. In conclusion, these findings indicate that targeting CDK9 by BAY1143572 significantly enhances the effects of radiation and Axl is a novel downstream target of CDK9 in esophageal adenocarcinoma.
细胞周期蛋白依赖性激酶9（CDK9）在转录水平上调节多种对辐射诱导的组织损伤至关重要的蛋白质和细胞通路。我们研究了新型高特异性CDK9抑制剂BAY1143572作为食管腺癌辐射增敏剂的作用。通过克隆形成试验评估CDK9抑制剂与辐射之间的协同作用。在包括患者肿瘤来源异种移植（PDX）在内的多个异种移植模型中评估CDK9抑制剂与辐射之间的协同作用。利用反向蛋白质阵列（RPPA）、蛋白质免疫印迹、免疫组织化学和定量聚合酶链反应（qPCR）来鉴定和验证CDK9抑制剂的靶点。与单独使用CDK9抑制剂或单独进行辐射治疗的队列相比，CDK9抑制剂加辐射显著降低了FLO-1、SKGT4、OE33和辐射抗性OE33R异种移植瘤及PDX的生长。RPPA确定Axl是CDK9抑制的候选靶点。蛋白质免疫印迹和qPCR表明，在FLO-1和SKGT4细胞中，无论有无辐射，用CDK9抑制剂处理后Axl mRNA（P = 0.02）和蛋白质水平均降低。用CDK9抑制剂与辐射联合处理的FLO-1异种移植瘤中Axl蛋白表达明显低于单独接受辐射处理的异种移植瘤（P = 0.003）。在FLO-1和SKGT4细胞中过表达Axl后进行的克隆形成试验增强了CDK9抑制剂的放射增敏作用，表明CDK9抑制剂的放射增敏作用依赖于Axl。总之，这些发现表明，BAY1143572靶向CDK9可显著增强辐射的作用，且Axl是食管腺癌中CDK9的一个新的下游靶点。
