Sarott Roman, Gourisankar Sai, Karim Basel, Nettles Sabin, Yang Haopeng, Dwyer Brendan G, Simanauskaite Juste M, Tse Jason, Abuzaid Hind, Krokhotin Andrey, Zhang Tinghu, Hinshaw Stephen M, Green Michael R, Crabtree Gerald R, Gray Nathanael S
bioRxiv. 2023 Oct 25:2023.10.23.563687. doi: 10.1101/2023.10.23.563687.
Protein kinases are disease drivers whose therapeutic targeting traditionally centers on inhibition of enzymatic activity. Here chemically induced proximity is leveraged to convert kinase inhibitors into context-specific activators of therapeutic genes. Bivalent molecules that link ligands of the transcription factor B-cell lymphoma 6 (BCL6) to ATP-competitive inhibitors of cyclin-dependent kinases (CDKs) were developed to re-localize CDK to BCL6-bound loci on chromatin and direct phosphorylation of RNA Pol II. The resulting BCL6-target proapoptotic gene expression translated into killing of diffuse large B-cell lymphoma (DLBCL) cells at 72 h with EC50s of 0.9 - 10 nM and highly specific ablation of the BCL6-regulated germinal center response in mice. The molecules exhibited 10,000-fold lower cytotoxicity in normal lymphocytes and are well tolerated in mice. Genomic and proteomic evidence corroborated a gain-of-function mechanism where, instead of global enzyme inhibition, a fraction of total kinase activity is borrowed and re-localized to BCL6-bound loci. The strategy demonstrates how kinase inhibitors can be used to context-specifically activate transcription, accessing new therapeutic space.
蛋白激酶是疾病驱动因子，其传统治疗靶点集中在抑制酶活性上。在此，利用化学诱导邻近效应将激酶抑制剂转化为治疗基因的背景特异性激活剂。开发了将转录因子B细胞淋巴瘤6（BCL6）的配体与细胞周期蛋白依赖性激酶（CDK）的ATP竞争性抑制剂连接起来的二价分子，以使CDK重新定位到染色质上与BCL6结合的位点，并直接使RNA聚合酶II磷酸化。由此产生的靶向BCL6的促凋亡基因表达在72小时内转化为对弥漫性大B细胞淋巴瘤（DLBCL）细胞的杀伤，其半数有效浓度（EC50）为0.9 - 10 nM，并在小鼠体内高度特异性地消除了BCL6调节的生发中心反应。这些分子在正常淋巴细胞中的细胞毒性低10000倍，并且在小鼠中耐受性良好。基因组和蛋白质组学证据证实了一种功能获得机制，即不是全局抑制酶活性，而是借用一部分总激酶活性并将其重新定位到与BCL6结合的位点。该策略展示了激酶抑制剂如何用于背景特异性激活转录，开拓新的治疗空间。
