Mikami K, Medová M, Nisa L, Francica P, Glück A A, Tschan M P, Blaukat A, Bladt F, Aebersold D M, Zimmer Y
Department of Radiation Oncology, Inselspital, Bern University Hospital and University of Bern, Bern, Switzerland. Department of Clinical Research, University of Bern, Bern, Switzerland.
Experimental Pathology, Institute of Pathology, University of Bern, Bern, Switzerland.
Mol Cancer Res. 2015 Dec;13(12):1544-53. doi: 10.1158/1541-7786.MCR-15-0022. Epub 2015 Sep 10.
Signaling via the MET receptor tyrosine kinase has been implicated in crosstalk with cellular responses to DNA damage. Our group previously demonstrated that MET inhibition in tumor cells with deregulated MET activity results in radiosensitization via downregulation of the ATR-CHK1-CDC25 pathway, a major signaling cascade responsible for intra-S and G2-M cell-cycle arrest following DNA damage. Here we aimed at studying the potential therapeutic application of ionizing radiation in combination with a MET inhibitor, EMD-1214063, in p53-deficient cancer cells that harbor impaired G1-S checkpoint regulation upon DNA damage. We hypothesized that upon MET inhibition, p53-deficient cells would bypass both G1-S and G2-M checkpoints, promoting premature mitotic entry with substantial DNA lesions and cell death in a greater extent than p53-proficient cells. Our data suggest that p53-deficient cells are more susceptible to EMD-1214063 and combined treatment with irradiation than wild-type p53 lines as inferred from elevated γH2AX expression and increased cytotoxicity. Furthermore, cell-cycle distribution profiling indicates constantly lower G1 and higher G2-M population as well as higher expression of a mitotic marker p-histone H3 following the dual treatment in p53 knockdown isogenic variant, compared with the parental counterpart.
The concept of MET inhibition-mediated radiosensitization enhanced by p53 deficiency is of high clinical relevance, as p53 is frequently mutated in numerous types of human cancer. The current data point for a therapeutic advantage for an approach combining MET targeting along with DNA-damaging agents for MET-positive/p53-negative tumors.
通过MET受体酪氨酸激酶的信号传导与细胞对DNA损伤的反应的串扰有关。我们小组先前证明，在MET活性失调的肿瘤细胞中抑制MET会通过下调ATR-CHK1-CDC25途径导致放射增敏，ATR-CHK1-CDC25途径是DNA损伤后负责S期和G2-M期细胞周期停滞的主要信号级联反应。在这里，我们旨在研究电离辐射与MET抑制剂EMD-1214063联合应用于p53缺陷癌细胞的潜在治疗应用，这些癌细胞在DNA损伤时G1-S检查点调节受损。我们假设，在抑制MET后，p53缺陷细胞将绕过G1-S和G2-M检查点，促进有大量DNA损伤的过早有丝分裂进入，并且比p53功能正常的细胞更容易发生细胞死亡。我们的数据表明，从γH2AX表达升高和细胞毒性增加推断，p53缺陷细胞比野生型p53细胞系对EMD-1214063以及与辐射联合治疗更敏感。此外，细胞周期分布分析表明，与亲本对应物相比，在p53敲低的同基因变体中进行双重治疗后，G1期细胞持续减少，G2-M期细胞增多，并且有丝分裂标记物磷酸化组蛋白H3的表达更高。
p53缺陷增强MET抑制介导的放射增敏的概念具有高度临床相关性，因为p53在多种人类癌症中经常发生突变。目前的数据表明，对于MET阳性/p53阴性肿瘤，将MET靶向与DNA损伤剂联合使用的方法具有治疗优势。
