Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota, USA.
Section of Cellular Dynamics, The Hormel Institute, University of Minnesota, Austin, Minnesota, USA.
Neuro Oncol. 2022 Oct 3;24(10):1700-1711. doi: 10.1093/neuonc/noac093.
H3K27M-mutant diffuse midline glioma (DMG) is a lethal brain tumor that usually occurs in children. Despite advances in our understanding of its underlying biology, efficacious therapies are severely lacking.
We screened a library of drugs either FDA-approved or in clinical trial using a library of patient-derived H3K27M-mutant DMG cell lines with cell viability as the outcome. Results were validated for clinical relevance and mechanistic importance using patient specimens from biopsy and autopsy, patient-derived cell lines, inhibition by gene knockdown and small molecule inhibitors, and patient-derived xenografts.
Kinase inhibitors were highly toxic to H3K27M-mutant DMG cells. Within this class, STAT3 inhibitors demonstrated robust cytotoxic activity in vitro. Mechanistic analyses revealed one form of activated STAT3, phospho-tyrosine- 705 STAT3 (pSTAT3), was selectively upregulated in H3K27M-mutant cell lines and clinical specimens. STAT3 inhibition by CRISPR/Cas9 knockout, shRNA or small molecule inhibition reduced cell viability in vitro, and partially restored expression of the polycomb repressive mark H3K27me3, which is classically lost in H3K27M-mutant DMG. Putative STAT3-regulated genes were enriched in an H3K27M-knockout DMG cell line, indicating relative gain of STAT3 signaling in K27M-mutant cells. Treatment of patient-derived intracranial xenografts with WP1066, a STAT3 pathway inhibitor currently in clinical use for pediatric brain tumors, resulted in stasis of tumor growth, and increased overall survival. Finally, pSTAT3(Y705) was detected in circulating plasma extracellular vesicles of patients with H3K27M-mutant DMG.
STAT3 is a biologically relevant therapeutic target in H3K27M-mutant DMG. STAT3 inhibition should be considered in future clinical trials.
H3K27M 突变弥漫中线脑胶质瘤（DMG）是一种致命的脑肿瘤，通常发生在儿童中。尽管我们对其基础生物学的认识有所提高，但有效的治疗方法却严重缺乏。
我们使用患者来源的 H3K27M 突变 DMG 细胞系文库，以细胞活力为结果，筛选了一个药物文库，这些药物要么是 FDA 批准的，要么是正在临床试验中的。使用活检和尸检的患者标本、患者来源的细胞系、基因敲低和小分子抑制剂的抑制作用以及患者来源的异种移植物，验证了结果的临床相关性和机制重要性。
激酶抑制剂对 H3K27M 突变 DMG 细胞具有高度毒性。在这一类中，STAT3 抑制剂在体外表现出强大的细胞毒性活性。机制分析表明，一种形式的激活 STAT3，磷酸酪氨酸 705 STAT3（pSTAT3），在 H3K27M 突变细胞系和临床标本中选择性地上调。CRISPR/Cas9 敲除、shRNA 或小分子抑制 STAT3 抑制可降低体外细胞活力，并部分恢复多梳抑制标记 H3K27me3 的表达，H3K27M 突变 DMG 中通常丢失该标记。假定的 STAT3 调节基因在 H3K27M 敲除 DMG 细胞系中富集，表明在 K27M 突变细胞中 STAT3 信号的相对获得。用 WP1066 治疗患者来源的颅内异种移植物，一种目前用于儿科脑肿瘤的 STAT3 途径抑制剂，导致肿瘤生长停滞，并增加总生存期。最后，在 H3K27M 突变 DMG 患者的循环血浆细胞外囊泡中检测到 pSTAT3（Y705）。
STAT3 是 H3K27M 突变 DMG 中的一个生物学相关的治疗靶点。在未来的临床试验中应考虑使用 STAT3 抑制剂。
