The RS4;11 cell line as a model for leukaemia with t(4;11)(q21;q23): Revised characterisation of cytogenetic features

Denise Ragusa; Evgeny M Makarov; Oliver Britten; Daniela Moralli; Catherine M Green; Sabrina Tosi

doi:10.1002/cnr2.1207

The RS4;11 cell line as a model for leukaemia with t(4;11)(q21;q23): Revised characterisation of cytogenetic features

Cancer Rep (Hoboken). 2019 Oct;2(5):e1207. doi: 10.1002/cnr2.1207. Epub 2019 Aug 7.

Authors

Denise Ragusa¹, Evgeny M Makarov^{1

2}, Oliver Britten¹, Daniela Moralli³, Catherine M Green³, Sabrina Tosi^{1

2}

Affiliations

¹ Division of Biosciences, College of Health and Life Sciences, Institute of Environment, Health and Societies, Brunel University London, Uxbridge, UK.
² Genome Engineering and Maintenance Network, Institute of Environment, Health and Societies, Brunel University London, Uxbridge, UK.
³ Chromosome Dynamics, Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK.

Abstract

Background: Haematological malignancies harbouring rearrangements of the KMT2A gene represent a unique subtype of leukaemia, with biphenotypic clinical manifestations, a rapid and aggressive onset, and a generally poor prognosis. Chromosomal translocations involving KMT2A often cause the formation of oncogenic fusion genes, such as the most common translocation t(4;11)(q21;q23) producing the KMT2A-AFF1 chimera.

Aim: The aim of this study was to confirm and review the cytogenetic and molecular features of the KMT2A-rearranged RS4;11 cell line and put those in context with other reports of cell lines also harbouring a t(4;11) rearrangement.

Methods and results: The main chromosomal rearrangements t(4;11)(q21;q23) and i(7q), described when the cell line was first established, were confirmed by fluorescence in situ hybridisation (FISH) and 24-colour karyotyping by M-FISH. Additional cytogenetic abnormalities were investigated by further FISH experiments, including the presence of trisomy 18 as a clonal abnormality and the discovery of one chromosome 8 being an i(8q), which indicates a duplication of the oncogene MYC. A homozygous deletion of 9p21 containing the tumour-suppressor genes CDKN2A and CDKN2B was also revealed by FISH. The production of the fusion transcript KMT2A-AFF1 arising from the der(11)t(4;11) was confirmed by RT-PCR, but sequencing of the amplified fragment revealed the presence of multiple isoforms. Two transcript variants, resulting from alternative splicing, were identified differing in one glutamine residue in the translated protein.

Conclusion: As karyotype evolution is a common issue in cell lines, we highlight the need to monitor cell lines in order to re-confirm their characteristics over time. We also reviewed the literature to provide a comparison of key features of several cell lines harbouring a t(4;11). This would guide scientists in selecting the most suitable research model for this particular type of KMT2A-leukaemia.

Keywords: KMT2A; MLL; RS4;11; clonal evolution; leukaemia; t(4;11)(q23;q21).

MeSH terms

Cell Line, Tumor
Chromosomes, Human, Pair 11 / genetics
Chromosomes, Human, Pair 4 / genetics
DNA-Binding Proteins / genetics*
Histone-Lysine N-Methyltransferase / genetics*
Humans
Karyotyping
Leukemia / genetics*
Leukemia / pathology
Myeloid-Lymphoid Leukemia Protein / genetics*
Oncogene Proteins, Fusion / genetics*
Sequence Deletion
Transcriptional Elongation Factors / genetics*
Translocation, Genetic

Substances

DNA-Binding Proteins
KMT2A protein, human
Oncogene Proteins, Fusion
Transcriptional Elongation Factors
Myeloid-Lymphoid Leukemia Protein
AFF1 protein, human
Histone-Lysine N-Methyltransferase