Molecular Modeling of the FOXO4-TP53 Interaction to Design Senolytic Peptides for the Elimination of Senescent Cancer Cells

Abstract

Background: Senescent cells accumulate in tissues over time as part of the natural aging process and the removal of senescent cells has shown promise for alleviating many different age-related diseases in mice. Cancer is an age-associated disease and there are numerous mechanisms driving cellular senescence in cancer that can be detrimental to recovery. Thus, it would be beneficial to eliminate senescent cancer cells to prevent cancer recurrence or progression. Methods: We used molecular modeling to develop a series of rationally designed peptides to mimic and target FOXO4 disrupting the FOXO4-TP53 interaction and releasing TP53 to induce apoptosis. We then tested these peptides as senolytic agents for the elimination of senescent cancer cells both in cell culture and in vivo. Findings: Here we show that these peptides can act as senolytics for eliminating senescent human cancer cells both in cell culture and in orthotopic mouse models. We then further characterized one peptide, ES2, showing that it co-localizes with FOXO4 foci and binds FOXO4 to a greater extent compared to TP53. Finally, we show that concomitant intra-tumoral injection of ES2 plus a BRAF inhibitor results in a significant increase in apoptosis in a transgenic mouse model of melanoma. Interpretation: Taken together, our results reveal that peptides can be generated to specifically eliminate FOXO4+ senescent cancer cells, which has implications for eradicating residual disease and as a combination therapy for frontline treatment of cancer. Funding Statement: This work was supported by the Cancer Early Detection Advanced Research Center at Oregon Health & Science University. Declaration of Interests: S.S. Cinaroglu, Y. Ahiska, U. Sezerman, G.B. Akcapinar, E. Timucin have a patent for the ES2 structure and are members of a company, Eternans Ltd. that is working on ES2 for therapeutic use. No potential conflicts of interest were disclosed by the other authors. Ethics Approval Statement: All experiments were approved by Oregon Health and Science University (OHSU) Institutional Animal Care and Use Committee (IACUC) (TR01_I0674) and conformed to the guidelines set by United States Animal Welfare Act and the National Institutes of Health.