In Silico–Designed <scp>TGFβRI</scp>/<scp>TGFβRII</scp> Receptor Complex Peptide Inhibitors Exhibit Biological Activity In Vitro

TGF-β (transforming growth factor β) is a pleiotropic cytokine found in three isoforms in humans. It regulates cell proliferation, wound healing, immune cell recruitment, contributes to epithelial-to-mesenchymal transition (EMT) and to the conversion of fibroblasts to myofibroblasts. TGF-β signalling pathway hyperactivity underlies many human disorders. The aim of this study was to evaluate a series of novel, in silico-designed peptide inhibitors (PIs) of the TGFβ/TGFβRI/TGFβRII complex. Luciferase-based luminescence assays on HEK293T cells were used to comparatively assess PI biological activity and calculate IC₅₀ values. Flow cytometry was used to assess PI cytotoxicity on HEK293T cells. The PIs caused significant luminescence level reductions compared to controls. Additionally, three of the PIs caused luminescence reductions that did not differ significantly from the effects of SD-208, a small molecule TGFβ inhibitor. None of the PIs exhibited cytotoxicity. Our TGFBR PIs have demonstrated activity in vitro, with no observed cytotoxicity. Our results suggest the PIs may be of interest in the treatment of fibrotic disorders, chronic inflammatory diseases, or certain neoplastic cancers. The PIs will be further refined in silico and tested via assays carried out on cancer cell lines and CD4+/CD8+ T cells.