CRISPR library screening analysis on DMSO and Erlotinib 10µM treated samples

ABSTRACT: Triple-negative breast cancers (TNBCs) are the most aggressive subtype of breast cancer that have poor prognosis and very few treatment options. Although approximately 40-70% of TNBC patients have EGFR overexpression, anti-EGFR therapies exerted little to no clinical benefit. This could be due to (i) the presence of an inherent resistance mechanism, (ii) the presence of EGFR protein in its inactive form, or (iii) lack of EGFR on the surface of plasma membrane. Several studies have shown that EGFR is present in the intracellular compartments, instead of the plasma membrane surface, in TNBC patients. Previous studies have demonstrated that intracellular EGFR renders TNBC tumors resistant to anti-EGFR therapies. Here, we used genome wide CRISPR library screening to identify the markers of resistance to EGFR inhibitors. Our CRISPR screening identified a redox protein, thioredoxin reductase 3 (TXNRD3), to be depleted in erlotinib-treated MDA-MB-231 cells suggesting that loss of TXNRD3 may sensitize TNBC cells to EGFR inhibitors. siRNA-induced knockdown and pharmacological inhibition of TXNRD3 using an FDA-approved drug auranofin significantly sensitized EGFR-high TNBC cells to EGFR inhibitors. Mechanistically, TXNRD3 knockdown or inhibition increased oxidative stress resulting in increased EGFR phosphorylation at Y1068 (active EGFR protein). Moreover, auranofin also increased surface accumulation of EGFR and sensitized SUM159PT cells to cetuximab-induced ADCC. Auranofin and erlotinib combination therapy exerted a significant anti-cancer activity in vivo in MDA-MB-231 cell line-derived xenograft and in murine syngeneic 4T1.2 TNBC model. Collectively, these data suggests that TXNRD3 inhibition using auranofin activates EGFR and increases its surface localization, which then sensitizes TNBC cells to anti-EGFR therapies. Hence, auranofin combined with anti-EGFR therapies may be a viable approach for the treatment of TNBC patients.

ORGANISM(S): Homo sapiens

PROVIDER: GSE279690 | GEO | 2025/09/01

REPOSITORIES: GEO