RMR is a peptide derived from the protein sequence flanking the threonine 209 phosphorylation site of the Runt-related transcription factor 3 (RUNX3) protein, chosen based on docking efficiency with the active site of P21 Activated Kinase 1 (PAK1), and ability to displace PAK1-RUNX3 interaction in models. PAK1 is an oncogenic serine/threonine kinase which modulates several signaling pathways involved in cancer, and phosphorylation of RUNX3 at T209 by PAK1 switches the function of RUNX3 from tumour suppressor to oncogene. RMR peptide is stable in vitro and in vivo, non toxic to normal cells, and inhibits threonine 209 phosphorylation in RUNX3 by PAK1. In cell culture models RMR peptide reduces proliferation of human oral squamous cell carcinoma samples, and in vivo causes 33% tumour regression in tumour xenograft models.
