Abstract

Background

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.

Methods

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.

Results

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.

Conclusions

DAC downregulates TERT through p21 induction. Our data point to TERT and DNMT1 levels as potential determinants of response to DAC treatment.

中文翻译：

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TERT和DNMT1表达预测神经胶质瘤对地西他滨的敏感性

摘要

背景

地西他滨（DAC）是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症患者。以前，我们表明DAC标记具有异柠檬酸脱氢酶1（IDH1）突变的神经胶质瘤的抗肿瘤活性。基于有希望的临床前结果，已经启动了一项临床试验，以确定DAC在IDH突变型神经胶质瘤中的作用。下一步是全面评估恶性神经胶质瘤对DAC的疗效和潜在决定因素。

方法

端粒酶逆转录酶（TERT）和DNMT1的表达和活性在患者来源的IDH1突变和野生型神经胶质瘤细胞系中被操纵，然后单独使用DAC处理或与端粒酶抑制剂联合评估细胞增殖。进行了RNA测序，《京都基因与基因组百科全书》（KEGG）富集以及相关分析。

结果

IDH1突变的神经胶质瘤球体具有半合子的染色体臂1p / 19q编码，对DAC特别敏感，并显示出对DNA复制基因的显着抑制作用。我们的转录组分析显示DAC诱导了细胞周期蛋白依赖性激酶抑制剂1A / p21（CDKN1A）的表达，并下调了TERT。阿霉素治疗后也观察到了这些分子变化，支持了DAC诱导的DNA损伤在促进这种作用中的重要性。我们证明了敲除p21导致了TERT上调。令人惊讶的是，TERT的过表达通过端粒酶非依赖性机制增加了DNMT1水平和DAC敏感性。此外，靶向DNMT1的RNA抑制（RNAi）消除了精通TERT的神经胶质瘤细胞中的DAC反应。

结论

DAC通过p21诱导下调TERT。我们的数据表明，TERT和DNMT1水平是对DAC治疗反应的潜在决定因素。