Dissecting the Transcriptional Regulation of the Tumor Antioxidant Response



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Tumors rely on hyperactive metabolism to maintain their proliferation rates, which generates ROS and results in lipid peroxidation. Excessive accumulation of lipid peroxides leads to ferroptosis, a newly discovered mechanism of cell death. Recent evidence suggests that lipid peroxides accumulate during radio- and immunotherapy, and are generated in cancer cells that colonize distant organs. Hence, understanding anti-ferroptotic pathways in cancer and sensitizing tumors to ferroptosis has emerged as a major opportunity for cancer treatment. Building upon this, we aim to identify master transcriptional regulators involved in cancer anti-ferroptotic response. To identify these transcription factors, a CRISPR/Cas9 screen was performed in a patient-derived lymphoma cell line targeting all putative transcription factors in the human genome. These cells were cultured under a control condition or grown in the presence of a compound that induces ferroptosis. Next-generation sequencing and bioinformatic analysis ranked each gene by its essentiality under ferroptosis, and the top hit of the screen was identified as anti-ferroptosis transcriptional regulator 1 (AFTR1), a two zinc-finger-containing transcription factor. The results of the screen were validated by knocking out AFTR1 in various cancer cell lines and confirming its essentiality in cell viability upon induction of ferroptosis, whereas it was not essential under standard conditions. The high amplification of the AFTR1 gene locus in several cancer types also indicated its potential as a target for cancer therapy. Therefore, these findings offer a promising opportunity to develop novel therapeutic strategies to sensitize cancer cells to ferroptosis and improve the efficacy of current therapies. ***This project was completed with contributions from Javier Garcia Bermudez from the Children's Medical Center Research Institute at UT Southwestern.