Odero M D, Zeleznik-Le N J, Chinwalla V, Rowley J D
University of Navarra, Pamplona, Navarra, Spain.
Genes Chromosomes Cancer. 2000 Dec;29(4):333-8.
Cell lines derived from patients with leukemia are used in many molecular biology studies. Here we report the cytogenetic analysis of the THP-1 cell line using G-banding, fluorescence in situ hybridization (FISH), and spectral karyotyping (SKY), and the molecular characterization of the MLL-AF9 rearrangement by RT-PCR. The THP-1 cell line was established from the peripheral blood of a 1-year-old boy with acute monocytic leukemia (AML-M5). THP-1 is near-diploid and consists of two related subclones with a number of aberrations, including the t(9;11), associated with AML M5. The use of FISH allowed us to identify and characterize otherwise hidden cytogenetic rearrangements, which include duplication of the 3' portion of MLL in the derivative 9 chromosome and a deletion of the 5' portion of the AF9 gene involved in the translocation. In addition to confirming the FISH results, SKY allowed for a more precise characterization of the karyotype of THP-1 and allowed us to identify other abnormalities in this cell line, including der(1)t(1;12), der(20)t(1;20), deletions 6p, 12p, and 17p, trisomy 8, and monosomy 10. Sequencing of the RT-PCR product showed a direct in-frame fusion product on the derivative chromosome 11 between exon 6 (exon 9) of MLL and exon 5 of AF9, which is most commonly involved in MLL-AF9 translocations. This study demonstrates that combining different techniques to achieve a more precise characterization of the THP-1 cell line provides important information that will be valuable for understanding the critical events required for leukemogenesis.
源自白血病患者的细胞系被用于许多分子生物学研究。在此，我们报告了使用G显带、荧光原位杂交（FISH）和光谱核型分析（SKY）对THP-1细胞系进行的细胞遗传学分析，以及通过逆转录聚合酶链反应（RT-PCR）对MLL-AF9重排进行的分子特征分析。THP-1细胞系源自一名1岁急性单核细胞白血病（AML-M5）男孩的外周血。THP-1接近二倍体，由两个相关的亚克隆组成，存在一些畸变，包括与AML M5相关的t(9;11)。FISH的使用使我们能够识别和表征其他隐藏的细胞遗传学重排，其中包括衍生9号染色体上MLL 3'部分的重复以及参与易位的AF9基因5'部分的缺失。除了证实FISH结果外，SKY还能更精确地表征THP-1的核型，并使我们能够识别该细胞系中的其他异常，包括der(1)t(1;12)、der(20)t(1;20)、6p、12p和17p缺失、8号染色体三体和10号染色体单体。RT-PCR产物的测序显示，在衍生的11号染色体上，MLL的外显子6（外显子9）与AF9的外显子5之间存在直接的读码框内融合产物，这是MLL-AF9易位中最常见的情况。这项研究表明，结合不同技术以更精确地表征THP-1细胞系可提供重要信息，这对于理解白血病发生所需的关键事件将具有重要价值。
