GPX4 inhibitors (Hainan University)

A highly selective ferroptosis inducer with drug-like properties can significantly advance the research on inducing ferroptosis for anticancer treatment. We previously reported a highly active GPX4 inhibitor 26a, but its activity and stability need further improvement. In this work, a novel GPX4 inhibitor (R)-9i with more potent cytotoxicity (IC₅₀ = 0.0003 μM against HT1080) and ferroptosis selectivity (selectivity index = 24933) was gained via further electrophilic warhead screening and structure-based optimization. The cellular thermal shift assay (CETSA) indicated that (R)-9i could stabilize GPX4 with a T_m value of 6.2 °C. Furthermore, (R)-9i showed strong binding affinity against GPX4 (K_D = 20.4 nM). More importantly, (R)-9i has more favorable pharmacokinetic properties than 26a, which endowed (R)-9i with potential in antitumor research and as a tool drug for further study of ferroptosis. Associated with these, (R)-9i treatment significantly inhibited tumor growth in the xenograft tumor mouse model without detectable toxicity.

Ferroptosis is a nonapoptotic type of cell death that is dependent on iron and involves the accumulation of reactive oxygen species. Ferroptosis suppressor protein 1 (FSP1) and glutathione peroxidase 4 (GPX4) are ferroptosis regulators that inhibit ferroptosis through independent pathways. This study assessed the prognostic value of GPX4 and FSP1 expression in colorectal cancer (CRC). We also examined the effects of FSP1 and GPX4 inhibition on cell survival of CRC cells.

This study included 206 surgical specimens from Stage II or III CRC patients. FSP1 and GPX4 expression was analyzed immunohistochemically, and the association of their expression levels with clinical outcome was evaluated. We also examined the effects of FSP1 and GPX4 inhibitors on the cell proliferative capacity of CRC cell lines.

Overall survival and recurrence-free survival were reduced in patients with high expression of FSP1 or GPX4, and those with both GPX4 and FSP1 expression showed worse prognosis. Positivity of both FSP1 and GPX4 was an independent poor prognostic factor for CRC patients. In CRC cells, the combination of GPX4 and FSP1 inhibitors led to more effective cell death than either inhibitor alone.

High expression of both GPX4 and FSP1 is a significant poor prognostic factor for CRC. Simultaneous inhibition of GPX4 and FSP1 to induce ferroptosis may be a novel therapeutic strategy in CRC.