SMYD2 is a lysine methyltransferase that catalyzes the monomethylation of several protein substrates including p53. SMYD2 is overexpressed in a significant percentage of esophageal squamous primary carcinomas, and that overexpression correlates with poor patient survival. However, the mechanism(s) by which SMYD2 promotes oncogenesis is not understood. A small molecule probe for SMYD2 would allow for the pharmacological dissection of this biology. In this report, we disclose LLY-507, a cell-active, potent small molecule inhibitor of SMYD2. LLY-507 is >100-fold selective for SMYD2 over a broad range of methyltransferase and non-methyltransferase targets. A 1.63-A resolution crystal structure of SMYD2 in complex with LLY-507 shows the inhibitor binding in the substrate peptide binding pocket. LLY-507 is active in cells as measured by reduction of SMYD2-induced monomethylation of p53 Lys(370) at submicromolar concentrations. We used LLY-507 to further test other potential roles of SMYD2. Mass spectrometry-based proteomics showed that cellular global histone methylation levels were not significantly affected by SMYD2 inhibition with LLY-507, and subcellular fractionation studies indicate that SMYD2 is primarily cytoplasmic, suggesting that SMYD2 targets a very small subset of histones at specific chromatin loci and/or non-histone substrates. Breast and liver cancers were identified through in silico data mining as tumor types that display amplification and/or overexpression of SMYD2. LLY-507 inhibited the proliferation of several esophageal, liver, and breast cancer cell lines in a dose-dependent manner. These findings suggest that LLY-507 serves as a valuable chemical probe to aid in the dissection of SMYD2 function in cancer and other biological processes.

中文翻译：

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LLY-507，一种具有细胞活性的、有效的、选择性的蛋白质赖氨酸甲基转移酶 SMYD2 抑制剂。

SMYD2 是一种赖氨酸甲基转移酶，可催化包括 p53 在内的多种蛋白质底物的单甲基化。SMYD2 在相当大比例的食管鳞状原发癌中过度表达，并且这种过度表达与患者生存率较差相关。然而，SMYD2 促进肿瘤发生的机制尚不清楚。SMYD2 的小分子探针将允许对该生物学进行药理学剖析。在本报告中，我们公开了 LLY-507，一种具有细胞活性的、有效的 SMYD2 小分子抑制剂。LLY-507 对 SMYD2 的多种甲基转移酶和非甲基转移酶靶标的选择性高出 100 倍以上。SMYD2 与 LLY-507 复合物的 1.63 A 分辨率晶体结构显示抑制剂结合在底物肽结合袋中。通过在亚微摩尔浓度下 SMYD2 诱导的 p53 Lys(370) 单甲基化减少来测量，LLY-507 在细胞中具有活性。我们使用 LLY-507 进一步测试 SMYD2 的其他潜在作用。基于质谱的蛋白质组学表明，LLY-507 抑制 SMYD2 对细胞整体组蛋白甲基化水平没有显着影响，亚细胞分级分离研究表明 SMYD2 主要存在于细胞质中，这表明 SMYD2 靶向特定染色质位点上的一小部分组蛋白，并且/或非组蛋白底物。通过计算机数据挖掘，乳腺癌和肝癌被鉴定为显示 SMYD2 扩增和/或过度表达的肿瘤类型。LLY-507 以剂量依赖性方式抑制多种食管癌细胞系、肝癌细胞系和乳腺癌细胞系的增殖。