Medizinische Universität Graz Austria/Österreich - Forschungsportal - Medical University of Graz
Gewählte Publikation:
Katschnig, AM.
Deficient Base Excision Repair in Acute Myeloid Leukemia. Consequences of Oxidative DNA Damage
[ Diplomarbeit/Master Thesis (UNI) ] Karl-Franzens Universität Graz; 2012. pp.97.
- Autor*innen der Med Uni Graz:
- Betreuer*innen:
- Sill Heinz
- Altmetrics:
- Abstract:
- Acute myeloid leukemia (AML) is an aggressive human neoplasm of the hematopoietic system characterized by genomic instability. A major contributor to mutagenic DNA damage is ROS, which is a manifold class of oxygen-derived radical species. The base excision repair (BER) pathway is specialized in removal of oxidized and alkylation-derived DNA damage, however, associations between BER deficiencies and myeloid leukemogenesis have not been elucidated yet. Preliminary data of our group have revealed a significant BER deficiency in a substantial proportion of AML patient samples and in five myeloid cell lines. The aim of my thesis was to evaluate the functional consequence of this BER deficiency and unravel underlying mechanisms. To pursue this issue, cytotoxicity assays using two ROSinducing agents, hydrogen peroxide (H2O2) and arsenic trioxide (ATO), and sequence analysis of initial BER genes of five BER proficient (BER+) and five BER deficient (BER-) cell lines were performed. To exclude diverging ROS metabolism in BER+ and BER- cell lines, flow-cytometric analysis of ROS induction after H2O2 treatment was accomplished before. However differences in ROS metabolism between both groups were not statistically significant. Evaluation of sensitivity of BER+ and BER- cell lines towards H2O2 and ATO indicated higher sensitivities of BER+ cell lines towards treatment, however, statistical evaluation using the Mann- Whitney-U test revealed no significant differences. Sequence analysis of the three initial BER genes MUTYH, NEIL 1/2 revealed a heterozygous A>G mutation (rs34612342) in exon 7 of MUTYH in the BER- cell line MONOMAC-1. Furthermore, a non-synonymous variation in MUTYH exon 12 (rs3219489) was found in this cell line. To reveal a compound heterozygous state of MUTYH, which might lead to loss of BER function, cloning and sequencing of MUTYH cDNA harboring the mutation and the SNP was performed. Compound heterozygosity of MUTYH in MONOMAC-1 could be confirmed. Furthermore, a heterozygous C>A variation (rs8191666) was found in exon 4 of NEIL2 in the BER- cell line Kasumi-1, which might affect the DNA binding domain of the glycosylase. These data demonstrate that treatment with H2O2 and ATO does not induce significantly different cytotoxicities in BER+ and BERmyeloid cell lines. However, single nucleotide variants might contribute to a functional BER impairment of distinct cell lines. Since DNA repair deficiencies have already been linked to cancer development, it is of great importance to further investigate these findings and the role of BER in the maintenance of genomic integrity.