Jiang, Qu ORCID: 0000-0001-8517-7750 (2023). The oncogenic role of the lysine-specific demethylase KDM1A in chronic lymphocytic leukemia. PhD thesis, Universität zu Köln.
PDF (Doctoral Dissertation)
Thesis_Qu Jiang_Final.pdf Download (22MB) |
Abstract
Chronic lymphocytic leukemia (CLL) is the most prevalent leukemia in adults in the Western world. Despite the advances in the identification of various genomic and molecular alterations and the management of treatment for CLL, it remains an incurable disease. Epigenetic alterations are considered to centrally shape the transcriptional signatures that drive disease evolution and underlie the biological and clinical subsets in CLL. However, characterizations of epigenetic regulators, particularly histone-modifying enzymes, are very rudimentary in CLL. Aberrant expression of the T-cell leukemia/lymphoma 1A (TCL1A) proto-oncogene is a hallmark of CLL and high TCL1A levels are associated with aggressive disease features. As a well-accepted disease model, Eμ-TCL1A transgenic (tg) mice produce B-cell proliferations that closely resemble human CLL. In the context of the yet-evolving molecular concept of the 14kDa TCL1A protein, it was shown that TCL1A interacts with the DNA methyltransferase 3A (DNMT3A), thereby reducing its enzymatic activity and contributing to epigenetic reprogramming in CLL. Fittingly, induced mono- or bi-allelic losses of Dnmt3a result in murine CLL. Nevertheless, the functional network around TCL1A, particularly with epigenetics, is incomplete and as a causal oncogene in CLL, a better molecular understanding would help in improving disease concepts and treatment rationales in this still incurable neoplasm. Here, we identify the epigenetic modifier, lysine-specific demethylase KDM1A as a novel interaction partner of the TCL1A protein in B cells. This demethylase has been implicated in many cancer entities and its overexpression has been linked to poor prognoses. Currently, KDM1A inhibitors are being investigated for cancer therapy in clinal trials. In this context, we proposed that KDM1A is involved in CLL pathogenesis by altering its epigenetic landscape. Therefore, we set out to address: (1) how does TCL1A affect KDM1A’s function/activity? (2) what are the biological outcomes of increased KDM1A levels in CLL? (3) which KDM1A-mediated pathways contribute to the biology of CLL? To address these central questions, we have analyzed the subcellular localization of TCL1A and KDM1A as well as their interacting complex. TCL1A interacted with KDM1A in the nucleus. Interestingly, their protein interaction increased the histone demethylase activity of KDM1A in B cells. TCL1A also affected histone posttranslational modifications (PTMs). Furthermore, we could show that KDM1A is overexpressed in CLL B cells as compared to healthy B cells. By analyzing the gene expression profiling (GEP) data of patients included in the CLL8 trial, we demonstrated that higher KDM1A expression levels and the associated gene signatures correlate with adverse clinical characteristics and unfavorable clinical outcomes, e.g., higher white blood cell (WBC) counts, higher serum thymidine kinase levels, a higher rate of TP53 mutations/deletions, and shorter progression-free survival (PFS). In addition, enrichment of different pathways involved in tumor progression was also associated with KDM1A expression levels. Next, we took advantage of the doxycycline (Dox)-inducible Kdm1a knockdown mouse model and the TCL1A-tg Eμ-TCL1A mice to achieve a whole-organismal Kdm1a knockdown in murine CLL. The genetic Kdm1a depletion in Eµ-TCL1A mice reduced the leukemic burden in peripheral blood, spleen, and bone marrow. This was accompanied by upregulation of p53 and pro-apoptotic pathways identified by RNA-sequencing analysis. The analysis of differentially expressed genes (DEGs) upon Kdm1a knockdown suggested that Kdm1a acts as a transcriptional repressor in murine CLL. This might be due to enrichment of regulatory elements of upregulated genes with H3K4 methylation upon the Kdm1a knockdown, which leads to activation these genes. Thus, we performed chromatin immunoprecipitation sequencing (ChIP-seq) experiments, which demonstrated an increase in H3K4me3 marks in Kdm1a knockdown leukemic cells. Moreover, KDM1A expression in the components of the microenvironment had an impact on their support for CLL progression. The loss of KDM1A in monocytic cells and stromal cells led to impaired support of CLL cell proliferation and survival in vitro. Notably, Kdm1a knockdown in Eµ-TCL1A prolonged the overall survival (OS) of leukemic animals. In vitro, KDM1A inhibition by the pharmacologic compound C12 induced apoptosis and increased H3K4/9 target methylation levels in leukemic B cells. Overall, in completion of all aims, we established a relevant pathogenic role for KDM1A in CLL, as a pro-oncogenic molecule in CLL cells and in components of their microenvironment. Our data further provide a rationale for therapeutic KDM1A inhibition in CLL.
Item Type: | Thesis (PhD thesis) | ||||||||||||
Translated abstract: |
|
||||||||||||
Creators: |
|
||||||||||||
URN: | urn:nbn:de:hbz:38-653494 | ||||||||||||
DOI: | 10.1182/blood.2022017230 | ||||||||||||
Date: | 6 April 2023 | ||||||||||||
Place of Publication: | Blood | ||||||||||||
Language: | English | ||||||||||||
Faculty: | Faculty of Medicine | ||||||||||||
Divisions: | CECAD - Cluster of Excellence Cellular Stress Responses in Aging-Associated Diseases | ||||||||||||
Subjects: | Medical sciences Medicine | ||||||||||||
Uncontrolled Keywords: |
|
||||||||||||
Date of oral exam: | 25 October 2022 | ||||||||||||
Referee: |
|
||||||||||||
Refereed: | Yes | ||||||||||||
URI: | http://kups.ub.uni-koeln.de/id/eprint/65349 |
Downloads
Downloads per month over past year
Altmetric
Export
Actions (login required)
View Item |