Molecular regulation of normal and leukemic hematopoietic cells by CITED2

Berger, G. (Gerbrig) (2013) Molecular regulation of normal and leukemic hematopoietic cells by CITED2. thesis, Medicine.

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Abstract

One of the major problems in acute myeloid leukemia (AML) is the inability to target leukemic stem cells (LSCs), resulting in recurrent and often resistant disease. Therefore, understanding the regulation of healthy hematopoietic as well as leukemic cells is vital to solve this problem. The transcriptional co-activator CITED2 is shown to be essential for normal hematopoiesis, and is also associated with leukemia. However, knowledge regarding the mechanisms by which CITED2 functions is limited. This study aims to clarify the regulatory mechanism of CITED2, emphasizing on the tumour suppressor protein p53 as a possible downstream target for inhibition. In normal hematopoietic stem and progenitor cells, knockdown of CITED2 resulted in decreased proliferation and a differentiation-shift towards myeloid, as revealed by long term cultures and colony-forming cell assays. The response to the chemotherapeutic agent cytarabine was investigated in the leukemic NB4 cell line by means of Annexin-V staining (apoptosis) and MTS assays (cell viability). Chemotherapy-induced apoptosis was reduced after overexpression of CITED2, and this effect was also observed by means of improvement in cell viability. On the other hand, cell viability upon cytarabine treatment was impaired in CITED2 knockdown cells and induction of chemotherapy-induced apoptosis was most effective in cells with CITED2 downregulation. Both observations could be rescued with additional downregulation of p53, functionally demonstrating that CITED2 interferes with chemotherapy-induced apoptosis in a p53-dependent manner. In addition, mass spectrometry analysis of protein-interaction partners for CITED2 demonstrates various ways in which CITED2 can be linked to p53, showing exciting new proteins for further research possible involved in CITED2 function. In conclusion, this project further explores the role of CITED2 in regulation of hematopoietic cells under both normal and leukemic conditions. CITED2 was shown to be a potential inhibitor of p53 function, interesting since malfunction of p53 is a common feature in cancers. These findings could help aid our understanding of mechanisms responsible for therapeutic resistance in leukemia.

Item Type:	Thesis (Thesis)
Supervisor name:	Schepers, Dr. H. and Schuringa, Prof. Dr. J.J.
Faculty:	Medical Sciences
Date Deposited:	25 Jun 2020 11:05
Last Modified:	25 Jun 2020 11:05
URI:	https://umcg.studenttheses.ub.rug.nl/id/eprint/2479

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