Gribble S M, Roberts I, Grace C, Andrews K M, Green A R, Nacheva E P
Department of Haematology, University of Cambridge, Cambridge, United Kingdom.
Cancer Genet Cytogenet. 2000 Apr 1;118(1):1-8. doi: 10.1016/s0165-4608(99)00169-7.
The transformation of chronic myeloid leukemia (CML) from a chronic phase to an acute phase is frequently accompanied by additional chromosome changes. Extensive chromosome G-banded studies have revealed the secondary changes are nonrandom and frequently include trisomy 8, isochromosome 17q, trisomy 19, or an extra copy of the Philadelphia chromosome. In addition to these secondary chromosome changes, complex structural rearrangements often occur to form marker structures that remain unidentified by conventional G-banded analysis. The CML-derived cell line, K562, has been widely used in research since it was originally established in 1975. The K562 karyotype however, has remained incomplete, and marker structures have never been fully described. Recent advances in fluorescence in situ hybridization (FISH) technology have introduced the possibility of chromosome classification based on 24-color chromosome painting (M-FISH). In this study, we report a clarified karyotype for K562 obtained by a combination of the following molecular cytogenetic techniques: comparative genomic hybridization (CGH), FISH mapping using locus-specific probes, and M-FISH. Multicolor FISH has identified the marker structures in this cell line. The characteristic marker chromosome in K562 has been confirmed by this study to be a der(18)t(1;18). Multicolor FISH confirmed the identity of marker structures partially identified by G-banding as der(6)t(6;6),der(17)t(9;17),der(21)t(1;21),der(5)t(5;6). In addition M-FISH has revealed a deleted 20q and a complex small metacentric marker comprised of material from chromosomes 1, 6, and 20. A cryptic rearrangement was revealed between chromosomes 12 and 21 that produced a structure that looks like a normal chromosome 12 homologue by G-banding analysis. Finally, M-FISH detected regions from chromosome 13 intercalated into two acrocentric markers.
慢性髓性白血病（CML）从慢性期转变为急性期时，常伴有额外的染色体变化。广泛的染色体G显带研究表明，继发性变化并非随机发生，常包括8号染色体三体、17号染色体长臂等臂染色体、19号染色体三体或额外的费城染色体拷贝。除了这些继发性染色体变化外，还经常发生复杂的结构重排，形成常规G显带分析无法识别的标记结构。CML衍生的细胞系K562自1975年最初建立以来，已广泛应用于研究。然而，K562的核型仍不完整，标记结构也从未得到充分描述。荧光原位杂交（FISH）技术的最新进展引入了基于24色染色体描绘（M-FISH）进行染色体分类的可能性。在本研究中，我们报告了通过以下分子细胞遗传学技术组合获得的K562的明确核型：比较基因组杂交（CGH）、使用位点特异性探针的FISH定位和M-FISH。多色FISH已识别出该细胞系中的标记结构。本研究证实K562中特征性的标记染色体为der(18)t(1;18)。多色FISH证实了G显带部分识别的标记结构为der(6)t(6;6)、der(17)t(9;17)、der(21)t(1;21)、der(5)t(5;6)。此外，M-FISH还揭示了20号染色体长臂缺失以及由1号、6号和20号染色体物质组成的复杂小中着丝粒标记。通过G显带分析发现12号和21号染色体之间存在隐匿性重排，产生了一个看起来像正常12号染色体同源物的结构。最后，M-FISH检测到13号染色体区域插入到两个近端着丝粒标记中。
