Journal Article

Dietary flavonoids induce <i>MLL</i> translocations in primary human CD34<sup>+</sup> cells

Sahar Barjesteh van Waalwijk van Doorn-Khosrovani, Jannie Janssen, Lou M. Maas, Roger W.L. Godschalk, Jan G. Nijhuis and Frederik J. van Schooten

in Carcinogenesis

Volume 28, issue 8, pages 1703-1709
Published in print August 2007 | ISSN: 0143-3334
Published online April 2007 | e-ISSN: 1460-2180 | DOI: https://dx.doi.org/10.1093/carcin/bgm102
Dietary flavonoids induce MLL translocations in primary human CD34+ cells

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Genetic abnormalities leading to infant leukemias already occur during fetal development and often involve rearrangements of the mixed-lineage leukemia (MLL) gene. These rearrangements resemble the aberrations observed in therapy-related leukemias following treatment with topoisomerase II (topoII)-inhibiting agents such as etoposide. Since flavonoids are potent topoII inhibitors, we examined the role of three widely consumed dietary flavonoids (quercetin, genistein and kaempferol) on the development of MLL rearrangements in primary human CD34+ cells. Using the neutral Comet assay, we demonstrated a dose-dependent double-strand break (DSB) formation after exposure to flavonoids. An incorrect repair of these DSBs resulted in chromosomal translocations that co-localized with those identified in infant leukemias. Most of these translocations were formed by microhomology-mediated end joining. Moreover, in all but one translocation, SINE/Alu or LINE/L1 repetitive elements were present in at least one side of the breakpoint junction. Beside MLL translocations, fluorescence in situ hybridization analysis demonstrated monosomy or trisomy of MLL in 8–10% of the quercetin-exposed CD34+ cells. Our study demonstrates that biologically relevant concentrations of flavonoids can induce MLL abnormalities in primary hematopoietic progenitor cells. This is particularly alarming knowing that the differences in metabolism and excretion rate between mother and fetus can lead to a higher flavonoid concentration on the fetal side. Therefore, it is important to raise public awareness and set guidelines for marketing flavonoid supplements to reduce the risk of infant leukemias.

Journal Article.  5072 words.  Illustrated.

Subjects: Clinical Cytogenetics and Molecular Genetics

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