Gene expression profiling of EZH2 mutant and wild type DLBCL cell lines treated with EZH2 inhibitor

Summary from the GEO: "We studied transcriptional changes by Affymetrix human microarrays in DLBCL cell lines as a result of treatment with GSK126, a potent, highly-selective, SAM-competitive, small molecule inhibitor of EZH2<br/>In eukaryotes, epigenetic post-translational modification of histones is critical for regulation of chromatin structure and gene expression. EZH2 is the catalytic subunit of the Polycomb Repressive Complex 2 (PRC2) and is responsible for repressing target gene expression through methylation of histone H3 on lysine 27 (H3K27). Over-expression of EZH2 is implicated in tumorigenesis and correlates with poor prognosis in multiple tumor types. Recent reports have identified somatic heterozygous mutations of Y641 and A677 residues within the catalytic SET domain of EZH2 in diffuse large B-cell lymphoma (DLBCL) and follicular lymphoma (FL). The Y641 residue is the most frequently mutated residue, with 22% of GCB (Germinal Cell B-cell) DLBCL and FL harboring mutations at this site. These lymphomas exhibit increased H3K27 tri-methylation (H3K27me3) due to altered substrate preferences of the mutant enzymes. However, it is unknown whether direct inhibition of EZH2 methyltransferase activity alone will be effective in treating lymphomas carrying activating EZH2 mutations. Herein, we demonstrate that GSK126, a potent, highly-selective, SAM-competitive, small molecule inhibitor of EZH2 methyltransferase activity, decreases global H3K27me3 levels and reactivates silenced PRC2 target genes. GSK126 effectively inhibits the proliferation of EZH2 mutant DLBCL cell lines and dramatically inhibits the growth of EZH2 mutant DLBCL xenografts in mice. Together, these data demonstrate that pharmacological inhibition of EZH2 activity may provide a promising treatment for EZH2 mutant lymphoma.<br/>10 DLBCL cell lines (7 mutant and 3 wild type EZH2), that were differentially sensitive to GSK126 in proliferation assays, were treated for 72 hours, in duplicate (n=2), with either DMSO (vehicle) or 500nM of GSK126, a potent selective EZH2 inhibitor. EZH2 mutant cell lines are Pfeiffer, KARPAS-422, WSU-DLCL2, SU-DHL-10, SU-DHL-6, DB and SU-DHL-4. EZH2 wildtype cell lines are HT, OCI-LY-19 and Toledo.<br/>10 DLBCL cell lines (7 mutant and 3 wild type EZH2), that were differentially sensitive to GSK126 in proliferation assays, were treated for 72 hours, in duplicate (n=2), with either DMSO (vehicle) or 500nM of GSK126, a potent selective EZH2 inhibitor. EZH2 mutant cell lines are Pfeiffer, KARPAS-422, WSU-DLCL2, SU-DHL-10, SU-DHL-6, DB and SU-DHL-4. EZH2 wildtype cell lines are HT, OCI-LY-19 and Toledo."

本摘要源自 GEO 数据库：我们研究了 GSK126 治疗DLBCL 细胞系时，通过 Affymetrix 人源微阵列检测到的转录变化。GSK126 是一种高效、高度选择性的 SAM 竞争性小分子抑制剂，能够抑制 EZH2 的甲基转移酶活性。在真核生物中，组蛋白的表观遗传后翻译修饰对于染色质结构和基因表达的调控至关重要。EZH2 是多梳抑制复合体 2 (PRC2) 的催化亚基，通过甲基化组蛋白 H3 的赖氨酸 27 位 (H3K27) 来抑制靶基因的表达。EZH2 的过表达与肿瘤的发生有关，并在多种肿瘤类型中与不良预后相关。近期研究表明，在弥漫性大 B 细胞淋巴瘤 (DLBCL) 和滤泡性淋巴瘤 (FL) 中，EZH2 的催化 SET 结构域存在 Y641 和 A677 位点的体细胞杂合突变。Y641 位点是突变最频繁的位点，其中 22% 的 GCB (原发细胞 B 细胞) DLBCL 和 FL 存在此位点突变。这些淋巴瘤由于突变酶底物偏好性的改变，表现出 H3K27 三甲基化 (H3K27me3) 的增加。然而，尚不清楚单独直接抑制 EZH2 甲基转移酶活性是否对携带激活型 EZH2 突变的淋巴瘤治疗有效。在本研究中，我们展示了 GSK126 能够降低全局 H3K27me3 水平，并重新激活沉默的 PRC2 靶基因。GSK126 能够有效抑制 EZH2 突变型 DLBCL 细胞系的增殖，并在小鼠体内显著抑制 EZH2 突变型 DLBCL 异种移植的生长。综上所述，EZH2 活性的药理抑制可能为 EZH2 突变淋巴瘤的治疗提供一种有希望的策略。本研究中，对 10 种 DLBCL 细胞系（7 种突变型和 3 种野生型 EZH2）进行了处理，这些细胞系在 GSK126 增殖实验中对 GSK126 的敏感性不同。处理持续 72 小时，重复两次（n=2），使用 DMSO（溶剂）或 500nM 的 GSK126，一种高效的 EZH2 抑制剂。EZH2 突变型细胞系包括 Pfeiffer、KARPAS-422、WSU-DLCL2、SU-DHL-10、SU-DHL-6、DB 和 SU-DHL-4。EZH2 野生型细胞系包括 HT、OCI-LY-19 和 Toledo。