Institute for Experimental Cancer Research in Pediatrics, Goethe-University, Komturstrasse 3a, Frankfurt 60528, Germany.
German Cancer Consortium (DKTK), Partner Site Frankfurt, Germany.
Cell Death Dis. 2017 Jun 15;8(6):e2879. doi: 10.1038/cddis.2017.239.
The lysine-specific demethylase 1 (LSD1) is overexpressed in several cancers including rhabdomyosarcoma (RMS). However, little is yet known about whether or not LSD1 may serve as therapeutic target in RMS. We therefore investigated the potential of LSD1 inhibitors alone or in combination with other epigenetic modifiers such as histone deacetylase (HDAC) inhibitors. Here, we identify a synergistic interaction of LSD1 inhibitors (i.e., GSK690, Ex917) and HDAC inhibitors (i.e., JNJ-26481585, SAHA) to induce cell death in RMS cells. By comparison, LSD1 inhibitors as single agents exhibit little cytotoxicity against RMS cells. Mechanistically, GSK690 acts in concert with JNJ-26481585 to upregulate mRNA levels of the proapoptotic BH3-only proteins BMF, PUMA, BIM and NOXA. This increase in mRNA levels is accompanied by a corresponding upregulation of BMF, PUMA, BIM and NOXA protein levels. Importantly, individual knockdown of either BMF, BIM or NOXA significantly reduces GSK690/JNJ-26481585-mediated cell death. Similarly, genetic silencing of BAK significantly rescues cell death upon GSK690/JNJ-26481585 cotreatment. Also, overexpression of antiapoptotic BCL-2 or MCL-1 significantly protects RMS cells from GSK690/JNJ-26481585-induced cell death. Furthermore, GSK690 acts in concert with JNJ-26481585 to increase activation of caspase-9 and -3. Consistently, addition of the pan-caspase inhibitor N-benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone (zVAD.fmk) significantly reduces GSK690/JNJ-26481585-mediated cell death. In conclusion, concomitant LSD1 and HDAC inhibition synergistically induces cell death in RMS cells by shifting the ratio of pro- and antiapoptotic BCL-2 proteins in favor of apoptosis, thereby engaging the intrinsic apoptotic pathway. This indicates that combined treatment with LSD1 and HDAC inhibitors is a promising new therapeutic approach in RMS.
赖氨酸特异性去甲基酶 1（LSD1）在包括横纹肌肉瘤（RMS）在内的几种癌症中过表达。然而，目前尚不清楚 LSD1 是否可以作为 RMS 的治疗靶点。因此，我们研究了 LSD1 抑制剂单独或与其他表观遗传修饰剂（如组蛋白去乙酰化酶（HDAC）抑制剂）联合使用的潜力。在这里，我们确定 LSD1 抑制剂（即 GSK690、Ex917）和 HDAC 抑制剂（即 JNJ-26481585、SAHA）的协同作用可诱导 RMS 细胞死亡。相比之下，LSD1 抑制剂作为单一药物对 RMS 细胞几乎没有细胞毒性。从机制上讲，GSK690 与 JNJ-26481585 协同作用，上调促凋亡 BH3 仅蛋白 BMF、PUMA、BIM 和 NOXA 的 mRNA 水平。mRNA 水平的增加伴随着 BMF、PUMA、BIM 和 NOXA 蛋白水平的相应上调。重要的是，BMF、BIM 或 NOXA 的单独敲低显着降低了 GSK690/JNJ-26481585 介导的细胞死亡。同样，GSK690/JNJ-26481585 共处理时 BAK 的遗传沉默显着挽救了细胞死亡。此外，过表达抗凋亡 BCL-2 或 MCL-1 可显着保护 RMS 细胞免受 GSK690/JNJ-26481585 诱导的细胞死亡。此外，GSK690 与 JNJ-26481585 协同作用可增加半胱天冬酶-9 和 -3 的激活。一致地，添加泛半胱天冬酶抑制剂 N-苄氧羰基-Val-Ala-Asp-氟甲基酮（zVAD.fmk）显着降低了 GSK690/JNJ-26481585 介导的细胞死亡。总之，LSD1 和 HDAC 抑制的同时抑制通过有利于凋亡的方式改变促凋亡和抗凋亡 BCL-2 蛋白的比例，从而使内在凋亡途径失活，从而协同诱导 RMS 细胞死亡。这表明 LSD1 和 HDAC 抑制剂的联合治疗是 RMS 的一种有前途的新治疗方法。
