Zakaria Z, Tivnan A, Flanagan L, Murray D W, Salvucci M, Stringer B W, Day B W, Boyd A W, Kögel D, Rehm M, O'Brien D F, Byrne A T, Prehn J H M
Centre for Systems Medicine, Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland, Dublin 2, Ireland.
National Centre for Neurosurgery, Beaumont Hospital, Dublin 9, Ireland.
Br J Cancer. 2016 Jan 19;114(2):188-98. doi: 10.1038/bjc.2015.420. Epub 2015 Dec 10.
Resistance to temozolomide (TMZ) greatly limits chemotherapeutic effectiveness in glioblastoma (GBM). Here we analysed the ability of the Inhibitor-of-apoptosis-protein (IAP) antagonist birinapant to enhance treatment responses to TMZ in both commercially available and patient-derived GBM cells.
Responses to TMZ and birinapant were analysed in a panel of commercial and patient-derived GBM cell lines using colorimetric viability assays, flow cytometry, morphological analysis and protein expression profiling of pro- and antiapoptotic proteins. Responses in vivo were analysed in an orthotopic xenograft GBM model.
Single-agent treatment experiments categorised GBM cells into TMZ-sensitive cells, birinapant-sensitive cells, and cells that were insensitive to either treatment. Combination treatment allowed sensitisation to therapy in only a subset of resistant GBM cells. Cell death analysis identified three principal response patterns: Type A cells that readily activated caspase-8 and cell death in response to TMZ while addition of birinapant further sensitised the cells to TMZ-induced cell death; Type B cells that readily activated caspase-8 and cell death in response to birinapant but did not show further sensitisation with TMZ; and Type C cells that showed no significant cell death or moderately enhanced cell death in the combined treatment paradigm. Furthermore, in vivo, a Type C patient-derived cell line that was TMZ-insensitive in vitro and showed a strong sensitivity to TMZ and TMZ plus birinapant treatments.
Our results demonstrate remarkable differences in responses of patient-derived GBM cells to birinapant single and combination treatments, and suggest that therapeutic responses in vivo may be greatly affected by the tumour microenvironment.
对替莫唑胺（TMZ）的耐药性极大地限制了胶质母细胞瘤（GBM）化疗的有效性。在此，我们分析了凋亡抑制蛋白（IAP）拮抗剂比瑞那潘增强市售及患者来源的GBM细胞对TMZ治疗反应的能力。
使用比色法细胞活力测定、流式细胞术、形态学分析以及促凋亡和抗凋亡蛋白的蛋白质表达谱分析，在一组市售及患者来源的GBM细胞系中分析对TMZ和比瑞那潘（birinapant）的反应。在原位异种移植GBM模型中分析体内反应。
单药治疗实验将GBM细胞分为TMZ敏感细胞、比瑞那潘敏感细胞以及对两种治疗均不敏感的细胞。联合治疗仅使一部分耐药GBM细胞对治疗敏感。细胞死亡分析确定了三种主要反应模式：A型细胞在对TMZ反应时容易激活半胱天冬酶 - 8并导致细胞死亡，而添加比瑞那潘进一步使细胞对TMZ诱导的细胞死亡敏感；B型细胞在对比瑞那潘反应时容易激活半胱天冬酶 - 8并导致细胞死亡，但对TMZ未表现出进一步的敏感性；C型细胞在联合治疗模式下未显示明显的细胞死亡或细胞死亡适度增强。此外，在体内，一种C型患者来源的细胞系在体外对TMZ不敏感，但对TMZ和TMZ加比瑞那潘治疗表现出强烈的敏感性。
我们的结果表明患者来源的GBM细胞对比瑞那潘单药和联合治疗的反应存在显著差异，并表明体内治疗反应可能受到肿瘤微环境的极大影响。
