Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taiwan; Department of Biochemistry and Molecular Cell Biology, School of Medicine, College of Medicine, Taipei Medical University, Taiwan.
Department of Neurosurgery, Taipei City Hospital Ren-Ai Branch, Taipei, Taiwan.
Life Sci. 2020 Aug 1;254:117807. doi: 10.1016/j.lfs.2020.117807. Epub 2020 May 16.
Xanthohumol (XN), a natural prenylated flavonoid isolated from Humulus lupulus L. (hops), possess the therapeutic effects in glioblastoma multiforme (GBM), which is a grade IV aggressive glioma in adults. However, low bioavailability and extractive yield limit the clinical applications of XN. To comprehensively investigate XN-mediated gene networks in inducing cell death is helpful for drug development and cancer research. Therefore, we aim to identify the detailed molecular mechanisms of XN's effects on exhibiting cytotoxicity for GBM therapy.
XN significantly induced GBM cell death and enhanced temozolomide (TMZ) cytotoxicity, a first-line therapeutic drug of GBM. XN-mediated transcriptome profiles and canonical pathways were identified. DNA repair signaling, a well-established mechanism against TMZ cytotoxicity, was significantly correlated with XN-downregulated genes. Replication factor C subunit 2 (RFC2), a DNA repair-related gene, was obviously downregulated in XN-treated cells. Higher RFC2 levels which occupied poor patient survival were also observed in high grade GBM patients and tumors. Inhibition of RFC2 reduced cell viability, induced cell apoptosis, and enhanced both XN and TMZ cytotoxicity. By intersecting array data, bioinformatic prediction, and in vitro experiments, microRNA (miR)-4749-5p, a XN-upregulated microRNA, was identified to target to RFC2 3'UTR and inhibited RFC2 expression. A negative correlation existed between miR-4749-5p and RFC2 in GBM patients. Overexpression of miR-4749-5p significantly promoted XN- and TMZ-mediated cytotoxicity, and reduced RFC2 levels.
Consequently, we suggest that miR-4749-5p targeting RFC2 signaling participates in XN-enhanced TMZ cytotoxicity of GBM. Our findings provide new potential therapeutic directions for future GBM therapy.
黄腐酚（XN）是一种从啤酒花（Humulus lupulus L.）中分离得到的天然类异戊二烯黄酮，对多形性胶质母细胞瘤（GBM）具有治疗作用，GBM 是成人中一种侵袭性的 IV 级神经胶质瘤。然而，低生物利用度和提取产率限制了 XN 的临床应用。全面研究 XN 诱导细胞死亡的基因网络有助于药物开发和癌症研究。因此，我们旨在确定 XN 对 GBM 治疗表现出细胞毒性的详细分子机制。
XN 显著诱导 GBM 细胞死亡并增强替莫唑胺（TMZ）的细胞毒性，TMZ 是 GBM 的一线治疗药物。XN 介导的转录组谱和经典途径被确定。DNA 修复信号，一种对抗 TMZ 细胞毒性的成熟机制，与 XN 下调基因显著相关。复制因子 C 亚基 2（RFC2）是一种与 DNA 修复相关的基因，在 XN 处理的细胞中明显下调。在高级别 GBM 患者和肿瘤中，也观察到占据较差患者生存的更高 RFC2 水平。抑制 RFC2 降低细胞活力，诱导细胞凋亡，并增强 XN 和 TMZ 的细胞毒性。通过阵列数据、生物信息学预测和体外实验的交叉，确定了微 RNA（miR）-4749-5p 是一种 XN 上调的微 RNA，靶向 RFC2 3'UTR 并抑制 RFC2 表达。在 GBM 患者中，miR-4749-5p 与 RFC2 之间存在负相关。miR-4749-5p 的过表达显著促进了 XN 和 TMZ 介导的细胞毒性，并降低了 RFC2 水平。
因此，我们认为 miR-4749-5p 靶向 RFC2 信号参与了 XN 增强 TMZ 对 GBM 的细胞毒性。我们的研究结果为未来 GBM 治疗提供了新的潜在治疗方向。
