Germline variant GFI1-36N affects DNA repair in AML cells resulting in sensitivity to DNA damage and repair therapy
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ABSTRACT: Transcriptional repressor Growth factor independence 1 (GFI1) is a key regulator of haematopoiesis. We previously established that the germline variant GFI1-36N promotes acute myeloid leukemia (AML) development, however the mechanism is not full elucidated. Here using multi-omics approach, we show GFI1-36N expression impedes DNA repair in leukemic cells. We demonstrate the presence of GFI1-36N is associated with increased frequency of chromosomal aberrations and mutational burden in murine and human AML cells. In particular, GFI1-36N modulates DNA repair pathways, O6-methylguanine-DNA-methyltransferase (MGMT) and homologous recombination repair (HR). Mechanistically, GFI1-36N exhibits impaired binding to Ndrg1 promoter element compared to GFI1-36S (wild type), causing decreased NDRG1 levels consequently leading to suppression of MGMT expression, imprinted at the transcriptome and proteome, thus leaving the AML cells vulnerable to DNA damaging agents. Targeting MGMT via temozolomide and HR via olaparib caused specifically extensive lethality in in vitro and ex vivo human and AML samples expressing GFI1-36N. Whereas the effects were insignificant on non-malignant GFI1-36S or GFI1-36N cells. Further, mice transplanted with GFI1-36N leukemic cells treated with combination of temozolomide and olaparib had a significantly longer AML-free survival than mice transplanted with GFI1-36S leukemic cells. In summary, we show that GFI1-36N disturbs DNA repair activity via NDRG1-MGMT axis and thus provides critical insights into novel therapeutic option for AML presented with GFI1-36N variant. Key Points Presence of GFI1-36N impedes Homologous DNA and MGMT DNA repair selectively in AML cells via the NDRG1-MGMT axis. Use of temozolomide and olaparib allows selectively targeting GFI1-36N leukemic cells. Introduction Gfi1 is a transcription factor which regulates the development of haematopoietic cells as well as neuronal and intestinal epithelial cells 1-5. We reported that a variant of GFI1, denominated GFI1-36N (characterized by an exchange of serine to asparagine at position 36), has a prevalence of 5-7% in a healthy control population but is found at an increased frequency of 10-15% among MDS and AML patients 6,7. The expression of germline variant GFI1-36N predisposes the carriers to develop de novo AML and MDS and correlates with a poor prognosis 6,7. Recently, we and other showed that malignant cells with GFI1-36N variant have increased H3K9-acetylation at target genes resulting in higher expression of genes required for cell survival and proliferation 8. GFI1 exerts its repressive role by recruiting histone-modifying enzymes (deacetylases HDAC1-3, demethylase LSD1, methyl transferase G9a) and regulates the accessibility of DNA to its target genes such as Hoxa9, Pbx1, Meis1, CSF1 and CSFR1 9-15. We also showed that GFI1 regulates apoptosis through its regulation of p53 in lymphoblastic leukemia 16 and we have demonstrated that GFI1 facilitates DNA repair 17. However, it is not known how these activities are affected in the GFI1-36N variant and whether the ability of GFI1 to regulate DNA repair pathways is maintained and how this might affect the development of myeloid malignancies. In this study, we leveraged multi-omics profiling to gain mechanistic insights into the molecular architecture that drives leukemia in the presence of GFI1-36N. We provide evidence that GFI1-36N interferes with DNA in leukemic myeloid cells, which leads to a higher frequency of genetic aberrations in MDS/AML cells. We also show that GFI1-36N myeloid leukemic cells are more sensitive to targeting MGMT and HR repair deficient cells, which opens a new selective therapeutic window to treat AML/MDS.
INSTRUMENT(S): Q Exactive HF
ORGANISM(S): Homo Sapiens (human)
TISSUE(S): Blood Cell, Blood
DISEASE(S): Acute Leukemia
SUBMITTER: Ashokkumar Jayavelu
LAB HEAD: Dr.Ashok Kumar Jayavelu
PROVIDER: PXD037433 | Pride | 2024-01-26
REPOSITORIES: Pride
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