Jiang Hongmei, Wang Yixuan, Wang Jingjing, Wang Yafei, Wang Sheng, He Enyang, Guo Jing, Xie Ying, Wang Jingya, Li Xin, Peng Ziyi, Wang Mengqi, Hou Jian, Liu Zhiqiang
The Province and Ministry Co-sponsored Collaborative Innovation Center for Medical Epigenetics, Tianjin Key Laboratory of Cellular Homeostasis and Human Diseases, Department of Physiology and Pathophysiology, School of Basic Medical Science, Tianjin Medical University, Tianjin, China.
Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Tianjin Key Laboratory of Cancer Prevention and Therapy, Tianjin's Clinical Research Center for Cancer, Tianjin, China.
Clin Transl Med. 2022 Apr;12(4):e744. doi: 10.1002/ctm2.744.
t(4;14)(p16;q32) cytogenetic abnormality renders high level of histone methyltransferase NSD2 in multiple myeloma (MM) patients, and predicts poor clinical prognosis, but mechanisms of NSD2 in promoting chemoresistance have not been well elucidated.
An epigenetics compound library containing 181 compounds was used to screen inhibitors possessing a prior synergistic effect with bortezomib (BTZ) in vitro. Molecular biology techniques were applied to uncover underlying mechanisms. Transcriptome profile assay was performed by RNA-seq. NSG mouse-based xenograft model and intra-bone model were applied to qualify the synergistic effect in vivo.
We identified an Aurora kinase A inhibitor (MLN8237) possessed a significant synergistic effect with BTZ on t(4;14) positive MM cells. Aurora A protein level positively correlated with NSD2 level, and gain- and loss-of-functions of Aurora A correspondingly altered NSD2 protein and H3K36me2 levels. Mechanistically, Aurora A phosphorylated NSD2 at S56 residue to protect the protein from cleavage and degradation, thus methylation of Aurora A and phosphorylation of NSD2 bilaterally formed a positive regulating loop. Transcriptome profile assay of MM cells with AURKA depletion identified IL6R, STC2 and TCEA2 as the downstream target genes responsible for BTZ-resistance (BR). Clinically, higher expressions of these genes correlated with poorer outcomes of MM patients. Combined administration of MLN8237 and BTZ significantly suppressed tumour growth in LP-1 cells derived xenografts, and remarkably alleviated bone lesion in femurs of NSG mice.
Aurora A phosphorylates NSD2 at S56 residue to enhance NSD2 methyltransferase activity and form a positive regulating loop in promoting MM chemoresistance, thus pharmacologically targeting Aurora A sensitizes t(4;14) positive MM to the proteasome inhibitors treatment. Our study uncovers a previously unknown reason of MM patients with t(4;14) engendering chemoresistance, and provides a theoretical basis for developing new treatment strategy for MM patients with different genomic backgrounds.
细胞遗传学异常t(4;14)(p16;q32)使多发性骨髓瘤（MM）患者体内组蛋白甲基转移酶NSD2水平升高，并预示着不良的临床预后，但NSD2促进化疗耐药的机制尚未完全阐明。
使用包含181种化合物的表观遗传学化合物库在体外筛选与硼替佐米（BTZ）具有协同作用的抑制剂。应用分子生物学技术揭示潜在机制。通过RNA测序进行转录组分析。基于NSG小鼠的异种移植模型和骨内模型用于验证体内的协同作用。
我们发现一种极光激酶A抑制剂（MLN8237）与BTZ对t(4;14)阳性MM细胞具有显著的协同作用。极光A蛋白水平与NSD2水平呈正相关，极光A的功能获得和缺失相应地改变了NSD2蛋白和H3K36me2水平。机制上，极光A在S56残基处磷酸化NSD2以保护该蛋白不被切割和降解，因此极光A的甲基化和NSD2的磷酸化双向形成一个正调控环。对AURKA缺失的MM细胞进行转录组分析确定IL6R、STC2和TCEA2为导致BTZ耐药（BR）的下游靶基因。临床上，这些基因的高表达与MM患者的较差预后相关。联合使用MLN8237和BTZ显著抑制了LP-1细胞来源的异种移植瘤的生长，并显著减轻了NSG小鼠股骨的骨病变。
极光A在S56残基处磷酸化NSD2以增强NSD2甲基转移酶活性，并在促进MM化疗耐药中形成一个正调控环，因此从药理学上靶向极光A可使t(4;14)阳性MM对蛋白酶体抑制剂治疗敏感。我们的研究揭示了t(4;14) MM患者产生化疗耐药的一个先前未知的原因，并为针对不同基因组背景的MM患者开发新的治疗策略提供了理论依据。
