Enzyme Engineering
Open Access

Abstract

A human peptide protects against therapy-induced leukemia

R. Wiehe

Cancer treatment with doxorubicin and etoposide increases the risk of rearrangements in the Mixed linage leukemia or myeloid/lymphoid leukemia (MLL) gene [1-3], encompassing a 7.3 kb breakpoint cluster region (MLLbcr) on chromosome 11 with a therapy-related 0.4 kb hotspot [2]. It was demonstrated that the mitochondrial enzyme endonuclease G (EndoG) accumulates in the nucleus after genotoxic treatment inducing replication stress where it cleaves the MLLbcr [4]. A GFPbased reporter plasmid mimicking MLLbcr rearrangements was engineered [5] and used to screen a fractionated lyophilized hemofiltrate peptide library from patients with chronic renal failure aiming at identification of a human peptide preventing MLLbcr rearrangements. Thus, cells were pretreated with peptides followed by etoposide or doxorubicin exposure and FACS analysis to detect GFP reconstitution. Following two rounds of chromatographic fractionation and mass spectrometric analysis, we identified a peptide that mitigates MLLbcr rearrangements in different cell types without affecting cell cycle or cell death (image). Immunofluorescence microscopy and chromatin immunoprecipitation revealed that the peptide inhibited nuclear EndoG accumulation and MLLbcr binding, whereas overall DNA damage was not influenced by the peptide. Taken together, we describe a human peptide preventing MLLbcr rearrangements by interfering with nuclear EndoG functions.

Published Date: 2020-10-31; Received Date: 2020-10-17