Session: Parallel session 10 - Health and biological sciences

Characterization of an Auranofin-resistant A2780 ovarian cancer cell line

Xhesika LIMAJ¹, Agnès DELAUNAY-MOISAN², Gwenaelle LE PAVEC², Tania GAMBERI³, Iman HADDAD¹, Joelle VINH¹, Giovanni CHIAPPETTA ¹

¹Spectrométrie de Masse Biologique et Protéomique, LPC, UMR ESPCI CNRS 8249, PARIS, France
²Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC) , Ville Gif-sur-Yvette, 91198, France
³Department of Experimental and Clinical Biomedical Sciences "Mario Serio", University of Florence, Florence 50134, Italy

Pathological conditions, like cancer, alter biological homeostasis pathways. In A2780 ovarian cancer cells the activation of Nuclear Factor Erythroid 2 Like 2 (Nrf2) increases in response of elevated Reactive Oxygen Species (ROS) levels. Auranofin (AF), a gold-based drug, impairs ROS scavenging efficiency in A2780 cells by inhibiting Thioredoxin Reductase 1 (TXNRD1) and inducing cell death. We performed a proteomic analysis on AF-sensitive (A2780S) and AF-resistant (A2780R) ovarian cancer cell lines to investigate the molecular mechanisms developed by resistant cells to escape cell death . A2780S and A2780R cells (N=3) were treated for 24h with 1µM AF, using untreated cells as control. Data were acquired using Data Independent Acquisition (DIA) with an Orbitrap Eclipse tribrid mass spectrometer (ThermoFisher Scientific).

Our proteomic dataset revealed a downregulation of Glutathione-specific gamma-glutamylcyclotransferase 1 (CHAC1) in the AF-treated or untreated A2780R cells, compared to the A2780S cells. CHAC1 is responsible for glutathione (GSH) degradation, and we hypothesize that CHAC1 could be involved in AF-mediated cell death. CHAC1 lower expression in the A2780R cells was confirmed by transcriptomic analysis. A GSH measurement at different time points revealed a slower GSH decrease in the AF-treated A2780R cells. Additionally, we observed downregulated retinoic acid (RA) cytoplasmatic and nuclear transporters (CRABP1 and CRABP2) in the A2780R cells. A cell viability assay showed that combining AF treatment with RA (10µM) decreased cell survival compared to the AF treatment only in the A2780S cells. Interestingly, combined AF with an agonist of the RA nuclear receptor RARα (BMS753, 10 µM) reduced both cell lines' viability. We hypothesize that BMS753 can enter the nucleous bypassing CRABP2 nuclear transport. CRABP1 and CRABP2 are involved in the regulation of cell growth inhibition and therefore it could be a resistance mechanism to AF-induced cell death.