CXCR4-EGFR heteromers show ligand-dependent changes in conformation and signaling

The chemokine CXCR4 receptor and epidermal growth factor receptor (EGFR) are cell surface receptors that are overexpressed in numerous types of cancer. In this study, we have investigated the formation of CXCR4-EGFR heteromers using bioluminescence resonance energy transfer (BRET) and nanobody-based proximity ligation assays (PLAs). The present study demonstrated that EGFR and CXCR4 can form oligomeric complexes that were capable of coupling to PLCγ, Gi proteins and β-arrestin-2. The presence of these oligomeric complexes was detected by PLA in native HeLa cells at endogenous levels of expression using receptor-selective nanobody-oligonucleotide conjugates. Furthermore, the individual receptor components of the oligomer underwent conformation changes in response to EGF and CXCL12, which in the case of Gi-signalling led to altered responses to combinations of CXCL12 and EGF. This may have clinical implications in those cancers where both EGFR and CXCR4 are overexpressed.