Molecular modelling 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 ageing 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 develop a senolytic that acts not only on ageing cells but also senescent cancer cells to prevent cancer recurrence or progression. Methods We used molecular modelling 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 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 disrupts FOXO4-TP53 foci, activates TP53 mediated apoptosis and preferentially binds FOXO4 compared to TP53. Next, we show that intratumoural delivery of ES2 plus a BRAF inhibitor results in a significant increase in apoptosis and a survival advantage in mouse models of melanoma. Finally, we show that repeated systemic delivery of ES2 to older mice results in reduced senescent cell numbers in the liver with minimal toxicity. Interpretation Taken together, our results reveal that peptides can be generated to specifically target and eliminate FOXO4+ senescent cancer cells, which has implications for eradicating residual disease and as a combination therapy for frontline treatment of cancer. Funding This work was supported by the Cancer Early Detection Advanced Research Center at Oregon Health & Science University.

Development of a novel senolytic by precise disruption of FOXO4-p53 complex

“…1). In this study, Le et al [6] take a different approach by disrupting the FOXO4-p53 interaction with FOXO4 blocking peptides, which enable release and activation of p53. Using an atomistic model to simulate the FOXO4-p53 interaction, Le et al identify the CR3 domain on FOXO4.…”

“…A series of peptides were then designed to target high-affinity binding to the CR3 domain. Le et al [6] further test these putative senolytic peptides in a wide range of senescent cell types. ES2 peptides show the most potent senolytic activity among others and are 3-7 times more effective than the previously reported peptide FOXO4-DRI in both in-vitro and in-vivo studies.…”

“…ES2 peptides show the most potent senolytic activity among others and are 3-7 times more effective than the previously reported peptide FOXO4-DRI in both in-vitro and in-vivo studies. Le et al [6] highlight the safety and efficacy of ES2 in combination with the chemotherapeutic Dabrafenib as a onetwo punch therapy in preclinical mouse models of melanoma.…”

“…Given the heterogeneity of senescent cancer cells in tumour regions and TIS in normal tissues at sites distal to a tumour, the selection and design of senolytics as therapeutics warrant extensive evaluation. Le et al [6] show compelling evidence for efficacy of senolytics in multiple xenograft cancer models. Notably, the combined therapies of ES2 and a Braf inhibitor result in greater elimination of both cancer and senescent cells as well as significant improvement in survival compared to chemotherapy alone.…”

“…The work of Le et al. in EBioMedicine [6] is based on the previously reported involvement of the FOXO4-p53 complex [1] , a key regulator of SCAPs. FOXO4 is elevated in senescent cells and essential for maintaining viability of senescent cells by sequestering p53 in the nucleus [1] .…”