Lavau C, Szilvassy S J, Slany R, Cleary M L
Systemix, Inc., Palo Alto, CA 94304, USA.
EMBO J. 1997 Jul 16;16(14):4226-37. doi: 10.1093/emboj/16.14.4226.
A subset of chromosomal translocations in acute leukemias results in the fusion of the trithorax-related protein HRX with a variety of heterologous proteins. In particular, leukemias with the t(11;19)(q23;p13.3) translocation express HRX-ENL fusion proteins and display features which suggest the malignant transformation of myeloid and/or lymphoid progenitor(s). To characterize directly the potential transforming effects of HRX-ENL on primitive hematopoietic precursors, the fusion cDNA was transduced by retroviral gene transfer into cell populations enriched in hematopoietic stem cells. The infected cells had a dramatically enhanced potential to generate myeloid colonies with primitive morphology in vitro. Primary colonies could be replated for at least three generations in vitro and established primitive myelomonocytic cell lines upon transfer into suspension cultures supplemented with interleukin-3 and stem cell factor. Immortalized cells contained structurally intact HRX-ENL proviral DNA and expressed a low-level of HRX-ENL mRNA. In contrast, wild-type ENL or a deletion mutant of HRX-ENL lacking the ENL component did not demonstrate in vitro transforming capabilities. Immortalized cells or enriched primary hematopoietic stem cells transduced with HRX-ENL induced myeloid leukemias in syngeneic and SCID recipients. These studies demonstrate a direct role for HRX-ENL in the immortalization and leukemic transformation of a myeloid progenitor and support a gain-of-function mechanism for HRX-ENL-mediated leukemogenesis.
急性白血病中的一部分染色体易位会导致与三胸相关蛋白HRX与多种异源蛋白融合。特别是，具有t(11;19)(q23;p13.3)易位的白血病表达HRX-ENL融合蛋白，并表现出提示髓系和/或淋巴系祖细胞恶性转化的特征。为了直接表征HRX-ENL对原始造血前体细胞的潜在转化作用，通过逆转录病毒基因转移将融合cDNA转导到富含造血干细胞的细胞群体中。被感染的细胞在体外产生具有原始形态的髓系集落的潜力显著增强。原代集落可以在体外传代至少三代，并在转移到补充有白细胞介素-3和干细胞因子的悬浮培养物中时建立原始髓单核细胞系。永生化细胞含有结构完整的HRX-ENL前病毒DNA，并表达低水平的HRX-ENL mRNA。相比之下，野生型ENL或缺乏ENL成分的HRX-ENL缺失突变体没有表现出体外转化能力。用HRX-ENL转导的永生化细胞或富集的原代造血干细胞在同基因和SCID受体中诱导髓系白血病。这些研究证明了HRX-ENL在髓系祖细胞的永生化和白血病转化中的直接作用，并支持HRX-ENL介导的白血病发生的功能获得机制。
