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Muhammad Ismail

Identifying Forkhead Box Q1 as a novel regulator of ferroptosis

Universität Rostock, 2023

https://doi.org/10.18453/rosdok_id00004666

Abstract: Ferroptosis, an iron-dependent form of regulated cell death, is characterized by phospholipid peroxidation and metabolic constraint. Ferroptosis has emerged to play an important role in cancer biology to contribute into many pathologies. Cells respond to ferroptotic stimuli by regulation of selenoproteins, including the key regulator of ferroptosis phospholipid hydroperoxide-reducing enzyme glutathione peroxidase 4 (GPX4). Though, the underlying mechanisms and signalling pathways of ferroptotic cell death remain relatively unknown. Current research aims at deeper understanding of the pathophysiological role of ferroptosis and how it may be exploited for the treatment of cancer and neurodegenerative diseases. In this cell-based study, the GPX4 inhibitor (1S, 3R)-RSL3 (RAS selective lethal) and the system xc- (a cysteine/glutamate antiporter system) inhibitor erastin were used to identify Forkhead Box Q1 (FOXQ1) as a promising factor involved in the regulation of cellular ferroptosis sensitivity. The transcription factor FOXQ1 is a member of forkhead proteins that control important functions in biological development and tumorigenesis. A very limited number of studies have investigated the role of the FOXQ1 in human cancer. However, whether FOXQ1 and FOXQ1-regulated genes have a potentially predictable role in ferroptosis remains to be further explored, since pleiotropic responses in different cell lines were observed in the present study. An overexpression cloning approach was used to elucidate the factors and cell-autonomous mechanisms that underlie the regulation of ferroptosis in the given cell line. Present data suggest increased sensitivity to ferroptosis in FOXQ1 overexpressing cells compared to control cells. The finding was expanded to a panel of human breast cancer cell lines to show that overexpression of FOXQ1 mediated the sensitivity to RSL3- and erastin-induced ferroptotic cell death. To demonstrate the effect of FOXQ1 mediated sensitivity to ferroptosis in stably overexpressing cancer cell lines, several ferroptosis regulatory genes were monitored at several time points. In an attempt to further illuminate the mechanism of ferroptosis execution, targeted knock out (KO) of FOXQ1 in different cancer cell lines was performed using CRISPR/CAS technology, which resulted in reduced invasive ability of the cells. Furthermore, it was demonstrated that FOXQ1 deletion results in lower proliferation rates of cells and cell death. Consequently, various cancer cell lines overexpressing FOXQ1 were generated to enable investigations on the role of FOXQ1 and the role of novel transcriptional targets of FOXQ1 in ferroptosis that may serve as a potential therapeutic target for the development of anticancer therapies.

doctoral thesis   free access