RAS-mutant AML LSCs originate from GMPs and drive clinical resistance to BH3 mimetics [scRNA-Seq]. RAS-mutant AML LSCs originate from GMPs and drive clinical resistance to BH3 mimetics [scRNA-Seq]

Cancer driver mutations often show distinct temporal acquisition patterns, but the biological basis for this, if any, remains unknown. RAS mutations occur invariably late in the course of acute myeloid leukemia (AML), upon progression or relapsed/refractory disease1-6. Here, by employing synthetic leukemogenesis in human cells, we first show that RAS mutations are obligatory late events that need to succeed earlier cooperating mutations. We provide the mechanistic explanation for this in a requirement for mutant RAS to specifically transform committed progenitors of the myelomonocytic lineage (granulocyte-monocyte progenitors, GMPs) harboring previously acquired driver mutations, revealing that advanced leukemic clones originate from a different cell type than more ancestral clones. Furthermore, we demonstrate that RAS-mutant leukemia stem cells (LSCs) give rise to monocytic disease, as frequently observed in patients with poor responses to treatment with the BCL2 inhibitor drug Venetoclax (VEN). We show that this is because RAS-mutant LSCs, in contrast to RAS-WT LSCs, have altered BCL2 family gene expression profiles and are resistant to VEN, driving clinical resistance and relapse with monocytic features. Our findings demonstrate that a specific genetic driver by imposing a specific LSC target cell restriction shapes the non-genetic cellular hierarchy of AML and critically impacts therapeutic outcomes in patients. Overall design: Single cell RNA-sequencing of AML patient bone marrow mononuclear cells using Chromium 10X Genomics 5' v1 protocol.

癌症驱动突变通常呈现独特的时序获得模式，但其背后的生物学基础（若存在）仍未明确。RAS突变在急性髓系白血病（acute myeloid leukemia, AML）的病程中始终发生于疾病进展或复发/难治阶段1-6。本研究通过在人类细胞中构建人工白血病发生体系，首次证实RAS突变是一类必需的晚期事件，其发生需以预先获得的协同突变为前提。针对这一现象，我们提出了机制性解释：突变型RAS需特异性转化携带有既往获得的驱动突变的髓单核细胞系定向祖细胞（granulocyte-monocyte progenitors, GMPs），这一发现表明晚期白血病克隆的起源细胞与更早期的祖先克隆存在显著差异。此外，我们证实RAS突变型白血病干细胞（leukemia stem cells, LSCs）可诱导单核细胞系疾病的发生，这一表型在对BCL2抑制剂维奈克拉（Venetoclax, VEN）治疗应答不佳的患者中较为常见。我们进一步揭示，该现象的成因在于：相较于RAS野生型（RAS-WT）白血病干细胞，RAS突变型白血病干细胞的BCL2家族基因表达谱发生改变，且对维奈克拉产生耐药性，最终导致临床耐药及伴单核细胞表型的疾病复发。本研究结果表明，特定的遗传驱动因子通过施加特定的白血病干细胞靶细胞限制，塑造了急性髓系白血病的非遗传细胞层级结构，并对患者的治疗结局产生关键性影响。
实验整体设计：采用Chromium 10X Genomics 5' v1 测序流程，对AML患者骨髓单个核细胞进行单细胞RNA测序。