1,4-dihydroxy Quininib Activates Ferroptosis Pathways in OMM2.5 cells: Implications for Treatment of Metastatic Uveal Melanoma.

Abstract

Purpose : Uveal melanoma (UM) is an ocular cancer, with propensity for lethal liver metastases. When
metastatic disease occurs, as few as 8% of patients survive beyond two years. Efficacious treatments
for metastatic UM are urgently needed. 1,4-dihydroxy quininib, a CysLT 1 receptor antagonist, alters
UM cancer hallmarks in vitro, ex vivo and in vivo. Here, the objective is to understand the 1,4-
dihydroxy quininib mechanism of action and its translational potential in UM.

Methods : Proteomic profiling identified proteins differentially expressed in OMM2.5 cells by 1,4-dihydroxy
quininib. Gene ontology classification revealed the most altered biological processes. Glutathione
peroxidase 4 (GPX4) expression was assessed by immunoblots of UM cell lines and
immunohistochemistry of liver tumours from an orthotopic OMM2.5-derived xenograft mouse
model. Glutathione and lipid hydroperoxide were measured by biochemical assays. Association
between expression of specific ferroptosis transcripts and disease-free-survival in UM patients was
performed using the Tissue Cancer Genome Atlas (TCGA).

Results : Proteome profiling revealed 1,4-dihydroxy quininib treatment alters expression of ferroptosis
markers in OMM2.5 cells. In agreement, after 1,4-dihydroxy quininib treatment, GPX4, a pivotal
ferroptosis modulator, was significantly decreased in immunoblots (p<0.001), while glutathione and
lipid hydroperoxide were significantly increased (p<0.5; p<0.001). Preliminary data suggests GPX4
expression is also decreased in liver tumours from an orthotopic OMM2.5-derived xenograft mouse
model treated with 25 mg/kg 1,4-dihydroxy quininib. TCGA analysis revealed high levels of
ferroptosis associated transcripts e.g. SCL7A11, ACSL3 to correlate with reduced disease-free-
survival in the disomy 3/normal BAP1 UM cohort.

Conclusions : 1,4-dihydroxy quininib induces ferroptosis, a form of cell death driven by iron-dependent
peroxidation of phospholipids, in OMM2.5 cells. High expression levels of key genes modulating
ferroptosis are associated with a worse prognosis in UM. Overall, our results support ferroptosis
modulation as a potential treatment approach for UM.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.