治疗性抗药性仍然是阻止H3K27M改变的弥漫性中线胶质瘤（DMG）进展的主要障碍。抗药性部分由ALDH阳性癌干细胞（CSC）驱动，H3K27M突变DMG活检中观察到高ALDH1A3表达。我们假设ALDH介导的干性和抗性可能在一定程度上由癌基因组蛋白本身驱动。删除H3K27M后，ALDH1A3表达显著下降，并伴随着星形标记表达的增加和神经球形成能力的丧失，表明分化。我们在这里展示了癌基因组蛋白通过Wnt依赖方式调节ALDH1A3的组蛋白乙酰化，并且H3K27M表达的丧失导致DMG对放射治疗的敏感性增加。H3K27M改变的DMG中观察到的Wnt信号增强可能源自癌基因组蛋白对Wnt抑制物EYA4的mRNA和蛋白表达的显著抑制。因此，我们的研究结果确定了EYA4作为DMG中的真正肿瘤抑制子，在抑制EYA4的同时，导致异常的Wnt信号传导来调控干性和分化。未来的研究将探讨EYA4在DMG中的过表达是否可以阻碍生长和侵袭。总之，我们对H3K27M介导的癌干性和分化调控机制有了深入的了解，为探索DMG的新治疗靶点提供了合理性。版权所有 © 2023. Elsevier Inc.出版。

Therapeutic resistance remains a major obstacle to preventing progression of H3K27M-altered Diffuse Midline Glioma (DMG). Resistance is driven in part by ALDH-positive cancer stem cells (CSC), with high ALDH1A3 expression observed in H3K27M-mutant DMG biopsies. We hypothesized that ALDH-mediated stemness and resistance may in part be driven by the oncohistone itself. Upon deletion of H3K27M, ALDH1A3 expression decreased dramatically and was accompanied by a gain in astrocytic marker expression and a loss of neurosphere forming potential, indicative of differentiation. Here we show that the oncohistone regulates histone acetylation through ALDH1A3 in a Wnt-dependent manner and that loss of H3K27M expression results in sensitization of DMGs to radiotherapy. The observed elevated Wnt signaling in H3K27M-altered DMG likely stems from a dramatic suppression of mRNA and protein expression of the Wnt inhibitor EYA4 driven by the oncohistone. Thus, our findings identify EYA4 as a bona fide tumor suppressor in DMG that upon suppression, results in aberrant Wnt signaling to orchestrate stemness and differentiation. Future studies will explore whether overexpression of EYA4 in DMG can impede growth and invasion. In summary, we have gained mechanistic insight into H3K27M-mediated regulation of cancer stemness and differentiation, which provides rationale for exploring new therapeutic targets for DMG.Copyright © 2023. Published by Elsevier Inc.