Induction of the chromosomal translocation t(14;18) by targeting the BCL-2 locus with specific binding I-125-labeled triplex-forming oligonucleotides

Dahmen, Volker; Schmitz, Sabine; Kriehuber, Ralf

doi:10.1016/j.mrgentox.2017.09.002

Journal Article

FZJ-2017-06705

Induction of the chromosomal translocation t(14;18) by targeting the BCL-2 locus with specific binding I-125-labeled triplex-forming oligonucleotides

Dahmen, V.FZJ* ; Schmitz, S.FZJ* ; Kriehuber, R. (Corresponding author)FZJ*

2017
Elsevier Science Amsterdam [u.a.]

Mutation research / Genetic toxicology and environmental mutagenesis 823, 58 - 64 (2017) [10.1016/j.mrgentox.2017.09.002]

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Abstract: Triplex-Forming oligonucleotides (TFO) bind sequence-specific to the DNA double helix in-vitro and in-vivo andare a promising tool to manipulate genes or gene regulatory elements. TFO as a carrier molecule for short-rangeparticle emitter such as Auger-Electron-Emitters (AEE) bear the potential to introduce radiation-induced sitespecificcomplex DNA lesions, which are known to induce chromosomal translocations. We studied gene expression,translocation frequency and protein expression in SCL-II cells after transfection with the AEE Iodine-125 (I-125) labeled TFO-BCL2 targeting the human BCL2 gene. The TFO-BCL2 binds to the BCL2 gene in closeproximity to a known major-breakage-region (mbr). SCL-II cells were transfected with I-125 labeled TFO andstored for decay accumulation. Monitoring of BCL2 translocations was done with the Fluorescence-In-Situ-Hybridization (FISH) method. The utilized FISH probes were designed to detect a t(14;18) translocation of theBCL2 gene, which is a common translocation leading to an overexpression of BCL2 protein. Analysis of BCL2gene expression levels was done via quantitative Real-Time PCR. Verification of gene expression on the proteinlevel was analyzed by Western blotting. The relative gene expression of BCL2 in I-125-TFO-BCL2 transfectedcells showed a significant up-regulation when compared to controls. Analysis of the BCL2 t(14;18) translocationfrequency revealed a significant 1.8- to 2-fold increase when compared to control cells. This 2-fold increase wasnot reflected on the protein level. We conclude that I-125 decays within the BCL2 gene facilitate the t(14;18)chromosomal translocation in the SCL-II cells and that the increased frequency contributes to the observedoverall enhanced BCL2 gene expression.

Keyword(s): Biology (2nd)

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