Department of Biomedical Sciences, University of Lausanne, Bugnon 7, 1005, Lausanne, Switzerland.
Cell Death Dis. 2020 Nov 30;11(11):1019. doi: 10.1038/s41419-020-03231-0.
It is of clinical importance to identify biomarkers predicting the efficacy of DNA damaging drugs (genotoxins) so that nonresponders are not unduly exposed to the deleterious effects of otherwise inefficient drugs. Here, we initially focused on the bleomycin genotoxin because of the limited information about the genes implicated in the sensitivity or resistance to this compound. Using a whole-genome CRISPR/Cas9 gene knockout approach, we identified ASH2L, a core component of the H3K4 methyl transferase complex, as a protein required for bleomycin sensitivity in L1236 Hodgkin lymphoma. Knocking down ASH2L in these cells and in the NT2D1 testicular cancer cell line rendered them resistant to bleomycin, etoposide, and cisplatin but did not affect their sensitivity toward ATM or ATR inhibitors. ASH2L knockdown decreased cell proliferation and facilitated DNA repair via homologous recombination and nonhomologous end-joining mechanisms. Data from the Tumor Cancer Genome Atlas indicate that patients with testicular cancer carrying alterations in the ASH2L gene are more likely to relapse than patients with unaltered ASH2L genes. The cell models we have used are derived from cancers currently treated either partially (Hodgkin's lymphoma), or entirely (testicular cancer) with genotoxins. For such cancers, ASH2L levels could be used as a biomarker to predict the response to genotoxins. In situations where tumors are expressing low levels of ASH2L, which may allow them to resist genotoxic treatment, the use of ATR or ATM inhibitors may be more efficacious as our data indicate that ASH2L knockdown does not affect sensitivity to these inhibitors.
确定预测 DNA 损伤药物（遗传毒素）疗效的生物标志物具有重要的临床意义，这样非应答者就不会因使用效率低下的药物而遭受不必要的有害影响。在这里，我们最初专注于博来霉素遗传毒素，因为关于涉及这种化合物敏感性或耐药性的基因的信息有限。我们使用全基因组 CRISPR/Cas9 基因敲除方法，鉴定出 ASH2L 作为霍奇金淋巴瘤对博来霉素敏感性所必需的蛋白质，它是 H3K4 甲基转移酶复合物的核心组成部分。在这些细胞和 NT2D1 睾丸癌细胞系中敲低 ASH2L 使它们对博来霉素、依托泊苷和顺铂产生耐药性，但不影响它们对 ATM 或 ATR 抑制剂的敏感性。ASH2L 敲低降低了细胞增殖，并通过同源重组和非同源末端连接机制促进了 DNA 修复。来自肿瘤癌症基因组图谱的数据表明，携带 ASH2L 基因突变的睾丸癌患者比未发生 ASH2L 基因突变的患者更有可能复发。我们使用的细胞模型源自目前部分（霍奇金淋巴瘤）或完全（睾丸癌）用遗传毒素治疗的癌症。对于这些癌症，ASH2L 水平可作为预测对遗传毒素反应的生物标志物。在肿瘤表达低水平 ASH2L 的情况下，这可能使它们能够抵抗遗传毒性治疗，使用 ATR 或 ATM 抑制剂可能更有效，因为我们的数据表明，ASH2L 敲低不影响对这些抑制剂的敏感性。
