Nakagawa-Saito Yurika, Mitobe Yuta, Togashi Keita, Suzuki Shuhei, Sugai Asuka, Kitanaka Chifumi, Okada Masashi
Department of Molecular Cancer Science, Yamagata University School of Medicine, Yamagata, Japan.
Department of Neurosurgery, Yamagata University School of Medicine, Yamagata, Japan.
Anticancer Res. 2023 Mar;43(3):1131-1138. doi: 10.21873/anticanres.16258.
BACKGROUND/AIM: Givinostat is a pan-histone deacetylase (HDAC) inhibitor that has demonstrated excellent tolerability as well as efficacy in patients with polycythemia vera. Accumulating in vitro and in vivo evidence suggests givinostat is also promising as a therapeutic agent targeting glioma stem cells (GSCs), the cancer stem cells of glioblastoma (GBM) considered responsible for its intractable nature. However, it remains to be shown how givinostat impacts the therapeutic effects of temozolomide, a DNA-alkylating agent and the key component of GBM treatment given not only during postoperative radiotherapy but also thereafter as maintenance chemotherapy.
The effects of givinostat and knockdown of O-methylguanine-DNA methyltransferase (MGMT) or Sp1 on the mRNA and protein expression of relevant genes in human GSC lines were examined by RT-PCR and western blot analyses. The dye exclusion method was used to evaluate cell viability.
Givinostat enhanced the cytotoxic activity of temozolomide in GSC lines expressing MGMT, in which the MGMT expression was shown to contribute to their temozolomide resistance. Givinostat inhibited MGMT expression in GSCs and, in parallel, the expression of Sp1, a transcription factor involved in the control of MGMT promoter activity. Knockdown experiments demonstrated Sp1 expression was indeed required for MGMT expression in GSCs.
Givinostat, in addition to its own cytotoxic activity, sensitizes GSCs to temozolomide by inhibiting Sp1-dependent MGMT expression in GSCs. Combining givinostat with temozolomide could therefore be a rational therapeutic strategy to effectively eliminate GSCs and thus help overcome the therapy resistance of GBM.
背景/目的：吉维司他是一种泛组蛋白去乙酰化酶（HDAC）抑制剂，已在真性红细胞增多症患者中显示出优异的耐受性和疗效。越来越多的体外和体内证据表明，吉维司他作为一种靶向胶质瘤干细胞（GSCs）的治疗药物也很有前景，胶质瘤干细胞是胶质母细胞瘤（GBM）的癌症干细胞，被认为是其难治性的原因。然而，吉维司他如何影响替莫唑胺的治疗效果仍有待研究，替莫唑胺是一种DNA烷化剂，也是GBM治疗的关键组成部分，不仅在术后放疗期间使用，而且在之后作为维持化疗使用。
通过RT-PCR和蛋白质印迹分析，研究吉维司他以及O-甲基鸟嘌呤-DNA甲基转移酶（MGMT）或Sp1基因敲低对人GSC系中相关基因mRNA和蛋白质表达的影响。采用染料排除法评估细胞活力。
吉维司他增强了替莫唑胺对表达MGMT的GSC系的细胞毒性活性，其中MGMT的表达被证明导致它们对替莫唑胺耐药。吉维司他抑制GSCs中MGMT的表达，同时也抑制Sp1的表达，Sp1是一种参与控制MGMT启动子活性的转录因子。基因敲低实验表明，Sp1的表达确实是GSCs中MGMT表达所必需的。
吉维司他除了自身的细胞毒性活性外，还通过抑制GSCs中Sp1依赖性MGMT的表达，使GSCs对替莫唑胺敏感。因此，将吉维司他与替莫唑胺联合使用可能是一种合理的治疗策略，以有效消除GSCs，从而有助于克服GBM的治疗耐药性。
