Neurotensin Receptor 1 Regulates HER4 Tyrosine Phosphorylation in Lung Cancer Cells

Neurotensin (NTS) binds to the G protein-coupled receptors (GPCRs) NTSR1 and NTSR2. NTSR1 regulates transactivation of the EGFR, HER2, and HER3, but its effects on HER4 are unknown. By Western blot, NTSR1 and HER4 were present in six lung cancer cell lines examined. In NCI-H522 or NCI-H661 cells, adding NTS increased phosphorylation (P) of tyrosine (Y) 1284 on HER4. Because SR48692 antagonized NTS's ability to increase P-HER4 or P-ERK, NTSR1 may play an important role in NSCLC. SR48692, HER4 siRNA, reactive oxygen species inhibitors, and the tyrosine kinase inhibitor ibrutinib inhibited NTS-induced P-HER4. Adding NTS to NCI-H661 cells increased the formation of HER4/HER4, HER4/ EGFR, and HER4/HER2 dimers. Adding NTS to NSCLC cells increased both P-ERK and P-AKT, which were inhibited by PD98059 and LY294002, respectively. The growth of NCI-H522 or NCI-H661 cells was stimulated by NTS or neuregulin 1 (NRG1), a HER4 ligand, but inhibited by SR48692 or ibrutinib. The results indicate that NTSR1 regulates HER4 transactivation, thereby increasing the proliferation of lung cancer cells.