title: Therapy-related acute myeloid leukemia-like MLL rearrangements are induced by etoposide in primary human CD34+ cells and remain stable after clonal expansion.
abstract: Rearrangements involving the MLL gene on chromosome band 11q23 are a hallmark of therapy-related acute myeloid leukemias following treatment with topoisomerase II poisons including etoposide. Therapy-related and de novo genomic translocation breakpoints cluster within a well-characterized 8.3-kb fragment of MLL. Repair of etoposide-stabilized DNA topoisomerase II covalent complexes may initiate MLL rearrangements observed in patients. We used a culture system of primary human hematopoietic CD34+ cells and inverse polymerase chain reaction to characterize the spectrum of stable genomic rearrangements promoted by etoposide exposure originating within an MLL translocation hotspot in therapy-related leukemia. Alterations to the region were observed at a readily detectable frequency in etoposide-treated cells. Illegitimate repair events after minimal repair included MLL tandem duplications and translocations, with minor populations of deletions or insertions. In stably repaired cells that proliferated for 10 to 14 days, the significant majority of illegitimate events were MLL tandem duplications, and several deletions, inversions, insertions, and translocations. Thus, etoposide promotes specific rearrangements of MLL consistent with the full spectrum of oncogenic events identified in leukemic samples. Although etoposide-initiated rearrangements are frequent, only a small subset of translocations occurs in cells that proliferate significantly.
authors.affiliation: Institute of Cancer Genetics, Department of Pathology, Columbia University College of Physicians and Surgeons, 1150 St Nicholas Ave, New York, NY, USA.
authors.forename: Jolanta
authors.initials: J
authors.lastname: Libura
authors.forename: Diana J
authors.initials: DJ
authors.lastname: Slater
authors.forename: Carolyn A
authors.initials: CA
authors.lastname: Felix
authors.forename: Christine
authors.initials: C
authors.lastname: Richardson
mesh_terms: D000208:Acute Disease; D018952:Antigens, CD34; D049109:Cell Proliferation; D002478:Cells, Cultured; D002999:Clone Cells; D004268:DNA-Binding Proteins / Q000235:genetics*; D005047:Etoposide / Q000009:adverse effects*; D005312:Fetal Blood; D015321:Gene Rearrangement / Q000187:drug effects*; D006412:Hematopoietic Stem Cells / Q000187:drug effects* / Q000473:pathology; D011495:Histone-Lysine N-Methyltransferase; D006801:Humans; D007951:Leukemia, Myeloid / Q000139:chemically induced* / Q000235:genetics; D051788:Myeloid-Lymphoid Leukemia Protein; D016609:Neoplasms, Second Primary / Q000235:genetics*; D011519:Proto-Oncogenes / Q000235:genetics*; D014157:Transcription Factors / Q000235:genetics*; D014178:Translocation, Genetic
chemical_list: D018952:Antigens, CD34; D004268:DNA-Binding Proteins; C497422:KMT2A protein, human; D014157:Transcription Factors; D051788:Myeloid-Lymphoid Leukemia Protein; D005047:Etoposide; D011495:Histone-Lysine N-Methyltransferase