Fig. 1: Lapatinib-tolerant OE19 persister cells exhibit NRF2-mediated transcriptional activation.

A OE19-PT cells were treated with lapatinib (500 nM) for 35 days and released from therapy for 1 day (OE19-PS) or 14 days (OE19-PT*) prior to being re-exposed to lapatinib (500 nM), neratinib (10 nM) or trastuzumab (10 µg/mL) for 3 days, or incubated with the GPX4 inhibitor RSL3 (500 nM) with or without the ferroptosis inhibitor Ferrostatin-1 (Fer-1, 1 µM) for 1 day. B Cell density was measured by crystal violet staining. One-way ANOVA was utilised to analyse statistical differences between treated versus mock treated cells with DMSO (n = 3). C, D X2K webtool was utilised to predict transcription factors interacting with regulatory binding regions of DEGs upregulated in OE19-PS (panel C) or in lapatinib-resistant OE19-R (panel D) cells compared with the OE19-PT cell line. E RNA-sequencing datasets were utilised to assess the level of NRF2 activity in OE19-PT and OE19-PS cells by GSVA of NRF2 core target gene signatures derived from human NSCLC and lymphoblastoid cells. Unpaired t-test was utilised to analyse statistical differences (n = 3). F Kaplan–Meier plot survival curves comparing subjects in the TCGA OAC cohort based on risk scores established from four NRF2 target genes. Samples were divided into two groups, high (red) and low (blue), based on the median value of risk scores. Cox regression was used to calculate the hazard ratio (HR) and the p-value.