The importance of molecular cytogenetic analysis prior to using cell lines in research: The case of the KG-1a leukemia cell line

Abstract

Abstract. KG-1 and its less differentiated subline KG-1a are leukemia cell lines used in research in a number of laboratories. The karyotypes of the two lines were initially identical. In the following years, further analysis revealed that the cell lines had acquired additional karyotypical abnormalities and differed in the presence of certain typical chromosomal rearrangements. To obtain cytogenetic authentication prior to the use of the two cell lines, we analyzed their karyotype by combining DAPI-and CMA-chromosome bandings and a fluorescence in situ hybridization (FISH)-based approach by using BAC clones useful for the identification of chromosome regions of interest. Sequences of the MYC, PLZF, RARA and BCR genes, that are known to play a critical role in leukemogenesis, and certain BAC clones mapped to five known common fragile sites (CFS) were used for the FISH analysis. A telomeric probe (TTAGGG)n and a set of BAC clones were used to characterize the marker chromosome der(1) that was observed in the cell line KG-1a. The existence of notable differences between the karyotype of the KG-1a cell line previously described, and that described in this study, demonstrate that the use of established cancer cell lines should be preceded by cytogenetic and/ or molecular characterization. IntroductionKG-1 and KG-1a leukemia cell lines have been used in research in numerous laboratories. KG-1, a cell line established in 1978 by Koeffler and Golde (1), was derived from the bone marrow of a male individual with erythroleukemia that developed into acute myeloid leukemia (AML). The KG-1 cells are mostly at the myeloblast or promyelocyte stage of maturation.KG-1a is a less differentiated subline of KG-1 developed after 35 passages. The karyotypes of the two lines were initially identical (2). The comparative karyotypic analysis of the two cell lines performed in subsequent years by other authors using various cytogenetic and molecular techniques (3,4) revealed that the cell lines had acquired additional karyotypical abnormalities and, although sharing several identical structural aberrations, differed in the presence of certain typical chromosomal rearrangements. Particularly, Mrózek et al (4) used G-banding, spectral karyotyping (SKY) and fluorescence in situ hybridization (FISH) analyses to produce a detailed description of chromosome aberrations in the KG-1 and KG-1a cell lines. Comparative analysis of the two karyotypes is extremely useful for authentication of the two cell lines.To obtain a characterization and cytogenetic authentication of the two cell lines prior to use, their karyotype was analyzed by combining DAPI-and CMA-chromosome bandings and a FISH-based approach. For FISH analyses a number of BAC clones useful for the identification of chromosome regions of interest were employed, including the MYC, retinoic acid receptor (RARA), promyelocytic leukemia zinc finger (PLZF) and breakpoint cluster region (BCR) genes. Evidence suggests that the MYC copy number gain has a role in human myeloid leukemia (5 and ref...

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“…These anomalies are mostly dependent on the karyotype, namely chromosomal rearrangements. For example, the first chromosome received a doubled long arm, the sixteenth chromosome's deleted short arm, two copies of the twenty-second chromosome, and a lack of the Y chromosome, among other things [16]. The KG-1a cells (ATCC, Manassas, VA, USA) were stored, maintained, and cultivated according to "Handling information" (atcc.org, KG-1a-CCL-246.1).…”