Abstract 2075: GPCRs for pituitary adenylate cyclase activating polypeptide regulate transactivation of HER3 in non-small cell lung cancer cells

Abstract

Abstract HER3, which lacks intrinsic kinase activity, plays an important role in cancer proliferation by formation of heterodimers with the EGFR or HER2 (Kiavue et al., Oncogene, 2019). Peptide GPCRs for pituitary adenylate cyclase activating polypeptide (PACAP) stimulate growth by transactivation of the EGFR and HER2 (Moody et al., JPET, 2012 and Peptides, 2019), but its effect on HER3 is unknown. The ability of PACAP to cause tyrosine phosphorylation of the EGFR, HER2 and HER3 was investigated. Using a panel of 17 non-small cell lung cancer (NSCLC) cell lines, mRNA for EGFR, HER2, HER3 was detected in 94%, 88%, and 100% of the cell lines, respectively. Addition of 100 nM PACAP but not vasoactive intestinal peptide to A549 cells increased EGFR, HER2 and HER3 tyrosine phosphorylation by 420, 240 and 190%, respectively. The increase is EGFR tyrosine phosphorylation was blocked by gefitinib or PACAP(6-38), a PAC1 antagonist. The increase in HER2 tyrosine phosphorylation caused by PACAP was inhibited by Herceptin or PACAP(6-38). The increase in HER3 tyrosine phosphorylation caused by PACAP was inhibited by the HER3 blocking antibody mAb3481 or PACAP(6-38). Immunoprecipitation experiments indicated the PACAP addition to A549 cells resulted in the formation of EGFR/HER2 and HER2/HER3 heterodimers, whereas addition of EGF resulted in EGFR/HER2 heterodimers and addition of the HER3 agonist neuregulin-1 resulted in HER2/HER3 heterodimers. Addition of N-acetyl-cysteine (antioxidant), Tiron (superoxide scavenger) or diphenylene iodonium (Nox/Duox inhibitor) impaired the ability of PACAP to cause EGFR, HER2 or HER3 transactivation. The results indicate that reactive oxygen species are essential for PACAP to cause EGFR, HER2 or HER3 transactivation in non small cell lung cancer cells. Citation Format: Terry W. Moody, Lingaku Lee, Robert T. Jensen. GPCRs for pituitary adenylate cyclase activating polypeptide regulate transactivation of HER3 in non-small cell lung cancer cells [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2075.