Biomedical Research Centre of Aragon (CIBA), IIS Aragon/University of Zaragoza, Zaragoza, Spain.
Department of Biochemistry and Molecular and Cell Biology, University of Zaragoza, Zaragoza, Spain.
Cell Death Differ. 2018 Sep;25(9):1536-1548. doi: 10.1038/s41418-018-0112-9. Epub 2018 May 9.
Cytotoxic CD8 T (Tc) cells are the main executors of transformed and cancer cells during cancer immunotherapy. The latest clinical results evidence a high efficacy of novel immunotherapy agents that modulate Tc cell activity against bad prognosis cancers. However, it has not been determined yet whether the efficacy of these treatments can be affected by selection of tumoural cells with mutations in the cell death machinery, known to promote drug resistance and cancer recurrence. Here, using a model of prophylactic tumour vaccination based on the LCMV-gp33 antigen and the mouse EL4 T lymphoma, we analysed the molecular mechanism employed by Tc cells to eliminate cancer cells in vivo and the impact of mutations in the apoptotic machinery on tumour development. First of all, we found that Tc cells, and perf and gzmB are required to efficiently eliminate EL4.gp33 cells after LCMV immunisation during short-term assays (1-4 h), and to prevent tumour development in the long term. Furthermore, we show that antigen-pulsed chemoresistant EL4 cells overexpressing Bcl-X or a dominant negative form of caspase-3 are specifically eliminated from the peritoneum of infected animals, as fast as parental EL4 cells. Notably, antigen-specific Tc cells control the tumour growth of the mutated cells, as efficiently as in the case of parental cells. Altogether, expression of the anti-apoptotic mutations does not confer any advantage for tumour cells neither in the short-term survival nor in long-term tumour formation. Although the mechanism involved in the elimination of the apoptosis-resistant tumour cells is not completely elucidated, neither necroptosis nor pyroptosis seem to be involved. Our results provide the first experimental proof that chemoresistant cancer cells with mutations in the main cell death pathways are efficiently eliminated by Ag-specific Tc cells in vivo during immunotherapy and, thus, provide the molecular basis to treat chemoresistant cancer cells with CD8 Tc-based immunotherapy.
细胞毒性 CD8 T（Tc）细胞是癌症免疫治疗过程中转化和癌细胞的主要执行者。最新的临床结果表明，新型免疫治疗药物能够调节 Tc 细胞活性，对预后不良的癌症具有很高的疗效。然而，目前还不确定这些治疗方法的疗效是否会受到肿瘤细胞中细胞死亡机制突变的影响，这些突变已知会促进耐药性和癌症复发。在这里，我们使用基于 LCMV-gp33 抗原和小鼠 EL4 T 淋巴瘤的预防性肿瘤疫苗模型，分析了 Tc 细胞在体内消除癌细胞的分子机制以及细胞凋亡机制突变对肿瘤发展的影响。首先，我们发现 Tc 细胞和 perf 和 gzmB 是在短期（1-4 小时）试验中有效消除 LCMV 免疫后 EL4.gp33 细胞所必需的，并且可以长期预防肿瘤的发生。此外，我们还表明，过表达 Bcl-X 或 caspase-3 显性负形式的抗原脉冲化疗耐药 EL4 细胞会从感染动物的腹膜中被特异性清除，速度与亲本 EL4 细胞一样快。值得注意的是，抗原特异性 Tc 细胞能像对亲本细胞一样有效地控制突变细胞的肿瘤生长。总之，凋亡抑制突变的表达既不能使肿瘤细胞在短期存活中获得优势，也不能使肿瘤细胞在长期肿瘤形成中获得优势。尽管涉及消除抗凋亡肿瘤细胞的机制尚未完全阐明，但坏死和细胞焦亡似乎都不参与其中。我们的研究结果首次提供了实验证据，证明在免疫治疗过程中，Ag 特异性 Tc 细胞能有效地在体内消除主要细胞死亡途径中具有突变的化疗耐药癌细胞，从而为基于 CD8 Tc 的免疫治疗治疗化疗耐药癌细胞提供了分子基础。
