Ligand-Based NMR Study of C-X-C Chemokine Receptor Type 4 (CXCR4)-Ligand Interactions on Living Cancer Cells

Peptides-binding G protein-coupled receptors play an important role in many pathological and physiological pathways. The assessment of the receptor-bound conformation of a peptidic ligand within a membrane receptor such as a GPCR is of outmost importance for a rational drug design of more potent analogues. In this work, we applied multiple ligand-based NMR methods to study the interaction of peptide heptamers, derived from the C-X-C Motif Chemokine 12 (CXCL12), and the C-X-C Chemokine Receptor Type 4 (CXCR4) on membranes of human T-Leukemia cells (CCRF-CEM cells). To the best of our knowledge, this is the first structural study reporting the receptor-bound conformation of a peptide to a GPCR directly on a living cell. The results obtained in the field of CXCL12/CXCR4 are proofs of concept, although important information for researchers dealing with the CXCR4 field arise. General application of the presented NMR methodologies is possible and surely may help to accelerate the discovery of new therapeutic agents targeting GPCRs.