Session: 603. Oncogenes and Tumor Suppressors: Poster I
Hematology Disease Topics & Pathways:
AML, HSCs, Adult, Diseases, Animal models, cell regulation, Biological Processes, Technology and Procedures, cytogenetics, Cell Lineage, Study Population, Myeloid Malignancies, genomics, genetic profiling, Clinically relevant, hematopoiesis, flow cytometry, NGS, RNA sequencing, pathogenesis
Results: We first identified the upregulation of CDKN1C in the presence of EVI1 overexpression using RNA-seq on sorted hematopoietic stem and progenitor leukemia cells from our previously published EVI1+ leukemia mouse model (EVI1TO) (Ayoub et al., 2018). Since CDKN1C/ P57 expression has been linked to high relapse rates in AML patients following chemotherapy (Radujkovic et al., 2016), we confirmed the upregulation of CDKN1C using RNA-seq on sorted populations (mononucleated cells (MNCs), leukemia stem cells (LSCs), and minimal residual disease (MRD)) from activated-MECOM AML patients in comparison to nonactivated-MECOM high risk AML patients (67 samples from 27 patients). Additionally, we found EVI1 overexpression produces a reversible block in differentiation and engraftment that can be rescued by ablating EVI1 overexpression or by additional mutations. In an effort to identify EVI1-induced transcriptional regulations for CDKN1C, we performed chromatin immunoprecipitation and sequencing (ChIP-seq) and assayed for transposase accessible Chromatin (ATAC-seq) using our in vivo and in vitro EVI1 overexpression models. ChIP-seq for EVI1 showed a binding site for EVI1 located 300 kb from CDKN1C transcription start site (TSS), and ATAC-seq in EVI1 overexpressing AML showed an open chromatin pattern at the CDKN1C TSS only in the presence of EVI1 overexpression. We are presently investigating the molecular mechanism involved in the transcriptional regulation of CDKN1C in the presence of EVI1 overexpression.
Conclusions: Our data suggest a correlation between EVI1 and CDKN1C expression in high risk AML with 3q abnormalities and provide insights into a potential molecular mechanism for MECOM activation in controlling leukemic stem cell quiescence and resistance to chemotherapy by upregulating CDKN1C.
Disclosures: Andreeff: Daiichi-Sankyo; Jazz Pharmaceuticals; Celgene; Amgen; AstraZeneca; 6 Dimensions Capital: Consultancy; Daiichi-Sankyo; Breast Cancer Research Foundation; CPRIT; NIH/NCI; Amgen; AstraZeneca: Research Funding; Centre for Drug Research & Development; Cancer UK; NCI-CTEP; German Research Council; Leukemia Lymphoma Foundation (LLS); NCI-RDCRN (Rare Disease Clin Network); CLL Founcdation; BioLineRx; SentiBio; Aptose Biosciences, Inc: Membership on an entity's Board of Directors or advisory committees; Amgen: Research Funding.