Abstract (eng)
Signal Transducer and Activator of Transcription 3 (STAT3) is downstream of pathways activated by several different stimuli and regulates target genes involved in development and differentiation of various cell types. STAT3 occurs in two alternatively spliced variants, STAT3α and STAT3β. In the context of cancer, STAT3 was shown to be abnormally expressed and depending on the cellular context can play a role either as oncogene or tumour-suppressor. Preliminary data indicate that the STAT3β isoform has a tumour suppressive function in acute myeloid leukaemia (AML). This master thesis project focused on the establishment of STAT3 knock-out and STAT3α or STAT3β overexpressing AML cell lines. Six AML cell lines were characterised for their basic expression of the STAT3 isoforms. Newly cloned CRISPR/Cas9-sgRNA plasmids were successfully validated in HEK 293T cells, demonstrating the KO on the mRNA, protein and genomic level. However, nucleofection of AML cell lines with the verified plasmids demonstrated a rapid drop in viability under selection with antibiotics. In a second approach, AML cell lines were infected with lentivirus containing plasmids carrying either STAT3α or STAT3β to induce overexpression. Transduction with a GFP control plasmid showed high efficiencies of lentiviral infection whereas cells infected with the STAT3 plasmids exhibited a drop in viability. So far we were not able to create stable cell lines for studying the role of STAT3 in AML. Additional experiments are necessary to address the problem of reduced viability when AML cells are nucleofected or lentivirally infected with the STAT3 sgRNA or STAT3 overexpression plasmids.