PAR2 promotes tumor-associated angiogenesis in lung adenocarcinoma through activating EGFR pathway

Metastasis of advanced lung adenocarcinoma (LUAD) is a key cause of cancer-related death, and angiogenesis is the main feature of tumor growth and metastasis.

The expression level of F2R like trypsin receptor 1(F2RL1) which encodes protease-activated receptor 2 (PAR2) protein in LUAD tissues was analyzed by bioinformatics. The effects of F2RL1 overexpression/silencing on cell proliferation and sphere-forming were analyzed by Cell Counting Kit-8 and colony formation assays, stem cell sphere-forming assay, and angiogenesis assay, respectively. The F2RL1 mRNA expression level and the PAR2 protein expression level, vascular endothelial growth factor A (VEGFA), and epidermal growth factor receptor (EGFR) in lung cancer cell lines were evaluated by real-time quantitative polymerase chain reaction and western blot. The level of VEGFA secreted by lung cancer cells was analyzed by Enzyme-linked immunosorbent assay (ELISA). The effect of F2RL1-mediated EGFR signaling on angiogenesis was further explored by EGFR inhibitor AG1478.

F2RL1 was substantially up-regulated in LUAD tissues and cells, and overexpression of F2RL1 could promote proliferation and stem cell sphere-forming of lung cancer cell lines, as well as formation of blood vessels and branch points of human umbilical vein endothelial cells (HUVECs). Meanwhile, overexpression of F2RL1 significantly upregulated VEGFA expression and promoted EGFR phosphorylation. EGFR inhibitor AG1478 treatment significantly down-regulated pEGFR, and AG1478 treatment reversed the promoting effect of cancer cell cultured medium (oe-F2RL1) on HUVEC angiogenesis.

In summary, this study revealed the molecular mechanism of PAR2 promoting LUAD angiogenesis by activating EGFR signaling pathway, which further improves our understanding of LUAD angiogenesis, and provides a potential therapeutic strategy for LUAD treatment.