Neurology Clinic and National Center for Tumor Diseases, University Hospital Heidelberg, Heidelberg, Germany.
Department of Neuropathology, Institute of Pathology, University Hospital Heidelberg, Heidelberg, Germany.
Neuro Oncol. 2021 Jan 30;23(1):76-87. doi: 10.1093/neuonc/noaa207.
Decitabine (DAC) is an FDA-approved DNA methyltransferase (DNMT) inhibitor that is used in the treatment of patients with myelodysplastic syndromes. Previously, we showed that DAC marks antitumor activity against gliomas with isocitrate dehydrogenase 1 (IDH1) mutations. Based on promising preclinical results, a clinical trial has been launched to determine the effect of DAC in IDH-mutant gliomas. The next step is to comprehensively assess the efficacy and potential determinants of response to DAC in malignant gliomas.
The expression and activity of telomerase reverse transcriptase (TERT) and DNMT1 were manipulated in patient-derived IDH1-mutant and -wildtype glioma lines, followed by assessment of cell proliferation with DAC treatment alone or in combination with telomerase inhibitors. RNA sequencing, Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment, and correlation analysis were performed.
IDH1-mutant glioma tumorspheres with hemizygous codeletion of chromosome arms 1p/19q were particularly sensitive to DAC and showed significant inhibition of DNA replication genes. Our transcriptome analysis revealed that DAC induced expression of cyclin-dependent kinase inhibitor 1A/p21 (CDKN1A), along with downregulation of TERT. These molecular changes were also observed following doxorubicin treatment, supporting the importance of DAC-induced DNA damage in contributing to this effect. We demonstrated that knockdown of p21 led to TERT upregulation. Strikingly, TERT overexpression increased DNMT1 levels and DAC sensitivity via a telomerase-independent mechanism. Furthermore, RNA inhibition (RNAi) targeting of DNMT1 abrogated DAC response in TERT-proficient glioma cells.
DAC downregulates TERT through p21 induction. Our data point to TERT and DNMT1 levels as potential determinants of response to DAC treatment.
地西他滨（DAC）是一种经美国食品药品监督管理局（FDA）批准的 DNA 甲基转移酶（DNMT）抑制剂，用于治疗骨髓增生异常综合征患者。此前，我们发现 DAC 对异柠檬酸脱氢酶 1（IDH1）突变的神经胶质瘤具有抗肿瘤活性。基于有前景的临床前结果，一项临床试验已经启动，以确定 DAC 在 IDH 突变型神经胶质瘤中的疗效。下一步是全面评估 DAC 在恶性神经胶质瘤中的疗效和潜在反应决定因素。
在患者来源的 IDH1 突变和野生型神经胶质瘤系中操纵端粒酶逆转录酶（TERT）和 DNMT1 的表达和活性，然后单独或与端粒酶抑制剂联合使用 DAC 处理来评估细胞增殖。进行 RNA 测序、京都基因与基因组百科全书（KEGG）富集和相关性分析。
1p/19q 染色体臂杂合性缺失的 IDH1 突变神经胶质瘤肿瘤球体对 DAC 特别敏感，并显示出 DNA 复制基因的显著抑制。我们的转录组分析表明，DAC 诱导细胞周期蛋白依赖性激酶抑制剂 1A/p21（CDKN1A）的表达，同时下调 TERT。在阿霉素处理后也观察到这些分子变化，这支持 DAC 诱导的 DNA 损伤在促成这种作用中的重要性。我们证明了 p21 的敲低导致 TERT 上调。引人注目的是，TERT 过表达通过非端粒酶依赖机制增加了 DNMT1 水平和 DAC 敏感性。此外，在 TERT 功能获得型神经胶质瘤细胞中，靶向 DNMT1 的 RNA 抑制（RNAi）消除了 DAC 反应。
DAC 通过诱导 p21 下调 TERT。我们的数据表明 TERT 和 DNMT1 水平是 DAC 治疗反应的潜在决定因素。
