Whole chromosome losses resulting in near-haploid karyotypes are found in a rare subgroup of treatment-refractory acute lymphoblastic leukemia. To systematically dissect the unique physiology and uncover susceptibilities that can be exploited in near-haploid leukemia, we leveraged single-cell RNA-Seq and computational inference of cell cycle stages to pinpoint key differences between near-haploid and diploid leukemia cells. Combining cell cycle stage-specific differential expression with gene essentiality scores from a genome-wide CRISPR-Cas9-mediated knockout screen, we identified the homologous recombination pathway component RAD51B as an essential gene in near-haploid leukemia. DNA damage analyses revealed significantly increased sensitivity of RAD51-mediated repair to RAD51B loss in the G2/M stage of near-haploid cells, suggesting a unique role of RAD51B in the homologous recombination pathway. Elevated G2/M and G1/S checkpoint signaling was part of a RAD51B signature expression program in response to chemotherapy in a xenograft model of human near-haploid B-ALL, and RAD51B and its associated programs were overexpressed in a large panel of near-haploid B-ALL patients. These data highlight a unique genetic dependency on DNA repair machinery in near-haploid leukemia and demarcate RAD51B as a promising candidate for targeted therapy in this treatment-resistant disease.
在治疗难治性急性淋巴细胞白血病的一个罕见亚群中，发现了导致近单倍体核型的全染色体丢失。为系统解析近单倍体白血病的独特生理机制并挖掘其潜在治疗靶点，我们运用单细胞RNA测序技术，结合细胞周期阶段的计算推断，精准定位了近单倍体与二倍体白血病细胞之间的关键差异。通过整合细胞周期阶段特异性差异表达分析与全基因组CRISPR-Cas9介导的基因敲除筛选所获基因必要性评分，我们鉴定出同源重组通路组分RAD51B为近单倍体白血病中的必需基因。DNA损伤分析显示，在近单倍体细胞的G2/M期，RAD51介导的修复途径对RAD51B缺失表现出显著增强的敏感性，提示RAD51B在同源重组通路中具有独特功能。在人源近单倍体B-ALL异种移植模型中，升高的G2/M和G1/S检查点信号构成RAD51B特征性表达程序对化疗应答的部分机制，且该特征程序在大量近单倍体B-ALL患者中过度表达。这些数据揭示了近单倍体白血病对DNA修复机制的特殊遗传依赖性，并确立RAD51B作为这一耐药性疾病靶向治疗的有前景候选靶点。
肿瘤(癌症)患者之家