Cancer Susceptibility to Stapled Oncolytic Peptides Is Dictated by Membrane Cholesterol and Inflammatory Signaling

Relapsed and refractory cancers effectively overcome diverse treatment modalities that primarily target nucleic acids and proteins. The plasma membranes of cancer cells represent an alternative and underutilized target, with the potential for membrane lysis to induce rapid, proinflammatory cell death that circumvents the challenges of intratumor heterogeneity and immune evasion. In this study, we repurposed StAMP51.2, a stapled magainin 2 peptide previously optimized for selective membrane lysis of Gram-negative bacteria, to target cancer cell membranes. The Profiling Relative Inhibition Simultaneously in Mixtures (PRISM) assay, a high-throughput cancer cytotoxicity screen, revealed cancer cells most vulnerable to StAMP51.2 and biomarkers of susceptibility, specifically reduced cholesteryl esters and elevated triacylglycerols. This signature was validated in pairs of sensitive (OCI-AML3 and THP-1) and resistant (K562 and KMS-11) leukemia cell lines, with their differential responses correlated to distinct lipidomic profiles. Susceptibility of OCI-AML3 cells in culture extended to the in vivo context, in which StAMP51.2 suppressed leukemic growth in orthotopic and intraperitoneal models. To further characterize the mechanism of action, StAMP51.2-resistant OCI-AML3 cells were generated, which required 4 months of low-level exposure. Strikingly, drug-resistant OCI-AML3 cells recapitulated the lipidomic phenotype of naturally resistant K562 cells. Transcriptomic analyses further revealed that lipid reprogramming was accompanied by pervasive downregulation of inflammatory signaling. Thus, in advancing StAMP51.2 as an oncolytic prototype, this study uncovered an immunoregulatory axis that links membrane integrity to inflammatory signaling.

A stapled oncolytic peptide targets cancer cell membranes and induces a lipid-inflammation axis that underlies susceptibility, offering a promising therapeutic strategy beyond traditional nucleic acid and protein targets.