Amplification of chromosomal region 8p11–12 is a common genetic alteration that has been implicated in the aetiology of lung squamous cell carcinoma (LUSC)^1,2,3. The FGFR1 gene is the main candidate driver of tumorigenesis within this region⁴. However, clinical trials evaluating FGFR1 inhibition as a targeted therapy have been unsuccessful⁵. Here we identify the histone H3 lysine 36 (H3K36) methyltransferase NSD3, the gene for which is located in the 8p11–12 amplicon, as a key regulator of LUSC tumorigenesis. In contrast to other 8p11–12 candidate LUSC drivers, increased expression of NSD3 correlated strongly with its gene amplification. Ablation of NSD3, but not of FGFR1, attenuated tumour growth and extended survival in a mouse model of LUSC. We identify an LUSC-associated variant NSD3(T1232A) that shows increased catalytic activity for dimethylation of H3K36 (H3K36me2) in vitro and in vivo. Structural dynamic analyses revealed that the T1232A substitution elicited localized mobility changes throughout the catalytic domain of NSD3 to relieve auto-inhibition and to increase accessibility of the H3 substrate. Expression of NSD3(T1232A) in vivo accelerated tumorigenesis and decreased overall survival in mouse models of LUSC. Pathological generation of H3K36me2 by NSD3(T1232A) reprograms the chromatin landscape to promote oncogenic gene expression signatures. Furthermore, NSD3, in a manner dependent on its catalytic activity, promoted transformation in human tracheobronchial cells and growth of xenografted human LUSC cell lines with amplification of 8p11–12. Depletion of NSD3 in patient-derived xenografts from primary LUSCs containing NSD3 amplification or the NSD3(T1232A)-encoding variant attenuated neoplastic growth in mice. Finally, NSD3-regulated LUSC-derived xenografts were hypersensitive to bromodomain inhibition. Thus, our work identifies NSD3 as a principal 8p11–12 amplicon-associated oncogenic driver in LUSC, and suggests that NSD3-dependency renders LUSC therapeutically vulnerable to bromodomain inhibition.

染色体区域 8p11–12 的扩增是一种常见的遗传改变，与肺鳞状细胞癌 (LUSC) 的病因有关^1,2,3。FGFR1基因是该区域内肿瘤发生的主要候选驱动因素⁴。然而，评估 FGFR1 抑制作为靶向治疗的临床试验均未成功⁵。在这里，我们鉴定组蛋白 H3 赖氨酸 36 (H3K36) 甲基转移酶 NSD3，其基因位于 8p11-12 扩增子中，是 LUSC 肿瘤发生的关键调节因子。与其他 8p11-12 候选 LUSC 驱动程序相比，NSD3的表达增加与其基因扩增密切相关。消融NSD3 , 但不是FGFR1，在 LUSC 小鼠模型中减弱肿瘤生长并延长生存期。我们确定了一个 LUSC 相关变体 NSD3(T1232A)，它在体外和体内显示出对 H3K36 (H3K36me2) 二甲基化的催化活性增加。结构动力学分析表明，T1232A 取代引起整个 NSD3 催化域的局部迁移率变化，以减轻自动抑制并增加 H3 底物的可及性。NSD3(T1232A) 在体内的表达加速了 LUSC 小鼠模型的肿瘤发生并降低了总体存活率。NSD3(T1232A) 病理生成 H3K36me2 重编程染色质景观以促进致癌基因表达特征。此外，NSD3 在某种程度上取决于其催化活性，促进人气管支气管细胞的转化和异种移植人 LUSC 细胞系的生长，扩增 8p11-12。NSD3 在来自含有NSD3扩增或 NSD3(T1232A) 编码变体减弱了小鼠的肿瘤生长。最后，NSD3 调节的 LUSC 衍生异种移植物对溴结构域抑制过敏。因此，我们的工作将 NSD3 确定为LUSC中主要的 8p11-12 扩增子相关致癌驱动因素，并表明 NSD3 依赖性使 LUSC 在治疗上易受溴结构域抑制的影响。