Fusion Gene EPHB4-MET Driven by HOXA9 and Exerted Oncogenic Activity in Non-Small Cell Lung Cancer

BACKGROUND: Non-small cell lung cancer (NSCLC) is a type of lung cancer with high mortality. Mesenchymal-to-epithelial transition (MET) fusions are present in NSCLC and are associated with tumorigenesis. The Ephrin type-B receptor 4 (EPHB4)-MET fusion gene is a recently discovered gene, and there is a lack of research on its oncogenicity and driving mechanisms. In this study, we focused on the oncogenic properties and mechanism of the EPHB4-MET fusion gene. METHODS: To create EPHB4-MET gene fusion cells, BEAS-2B cells were infected with lentivirus harboring EPHB4-MET. The expression efficiency was measured using reverse-transcriptase polymerase chain reaction (RT-PCR). Subsequently, cell counting kit-8 (CCK-8), crystal violet staining, and transwell assays were performed to investigate the oncogenicity of EPHB4-MET gene fusion. Finally, dual luciferase assay and chromatin immunoprecipitation (ChIP) were used to probe the binding of homeobox domain transcription factor A9 (HOXA9) to the EPHB4 promoter. RESULTS: EPHB4-MET expression increased after infection with lentivirus, indicating that the gene fusion cell construction was successful. In addition, EPHB4-MET promoted MET activation of the downstream AKT pathway. Genes harboring EPHB4-MET significantly promoted cell proliferation, cell migration, and invasion. Subsequent research showed that via binding to the EPHB4 promoter region, HOXA9 induced the expression of EPHB4-MET, and knockdown of HOXA9 inhibited EPHB4-MET-induced oncogenic properties. CONCLUSION: In this study, we demonstrated that HOXA9 drove the expression of the fusion gene EPHB4-MET and exerted a tumorigenesis signature. HOXA9 may be a useful target for both diagnosis and treatment in patients with EPHB4-MET fusion genes in lung cancer.