Double vulnerability of active-NRF2 lung squamous cell carcinoma to NRF2 and TRIM24

Abstract

Lung squamous cell cancer (LUSC) is associated with very poor survival due to the lack of specific treatments. A common genetic alteration in LUSC involves mutations in (protein named NRF2) or its regulator, , resulting in increased activity of the NRF2 transcription factor (TF). This study compares the requirement for active-NRF2 in LUSC cell lines. Although normal-NRF2 cells are more sensitive to oxidative stress, they do not require NRF2 for survival under non-stress conditions, in contrast, LUSC cells with active-NRF2 mutations depend on NRF2 for viability. NRF2 depletion in patient-derived organoid cultures with active-NRF2 as well as in xenografts with active-NRF2 triggers cell death. The focus of this study is to find genes that rescue cell death upon NRF2-depletion in active-NRF2 cells. A CRISPRa/dCas9 screening for gene targets capable of rescuing cell survival in these cells identified as a gene whose expression saves cell survival in NRF2-depleted active-NRF2 LUSC cells. Alongside oxidative stress, the lack of TRIM24 selectively contributed to the induction of cell death (apoptosis and ferroptosis) in active-NRF2 LUSC cells. Cells with a high copy number ratio also undergo cell death. The increase in cell death observed upon TRIM24 depletion involves a reduction of TRIM24/PI3Kα complexes which destabilizes the PI3Kα catalytic subunit. Notably, overexpression of PI3Kα rescues cell survival in TRIM24-depleted active-NRF2 cells. These findings point to novel therapeutic approaches in LUSC.