E2F1-mediated repression of WNT5A expression Promotes Brain Metastasis Dependent on the ERK1/2 pathway in EGFR-Mutant Non-Small Cell Lung Cancer
Abstract Background: Brain metastasis (BM) is associated with poor prognosis in patients with advanced non-small cell lung cancer (NSCLC). Epidermal growth factor receptor (EGFR) mutation reportedly enhances the development of BM. However, the exact mechanism of how EGFR-mutant NSCLC contributes to BM remains unknown. This study was aimed at exploring the mechanism of BM development in EGFR-mutant NSCLC.Methods: WNT5A, was identified by analyzing RNA sequencing data of BM tissue from NSCLC. The expression of WNT5A in NSCLC plasma (n=94) and cells were detected by quantitative real-time PCR (qRT-PCR) and western blotting. WNT5A functions were examined by cell viability, migration, invasion, and immunohistochemistry assay in vitro. A xenograft nude mouse model and BM model were used to observe tumor growth and brain metastasis in vivo. The potential transcription factor of WNT5A was explored using bioinformatics analysis and verified by chromatin immunoprecipitation (ChIP) and luciferase reporter assays. WNT5A targets in NSCLC cells were confirmed using luciferase reporter assay, qRT-PCR, and western blotting.Results: WNT5A was downregulated in BM tissues and EGFR-mutant samples and cells. The overexpression of WNT5A inhibited the growth, migration, and invasion of EGFR-mutant cells in vitro and retarded tumor growth and metastasis in vivo compared to the EGFR wide-type cells. ChIP and luciferase reporter assays showed that E2F1 negatively regulated WNT5A at transcriptional levels, which was suppressed by ERK1/2 inhibitor (U0126) in EGFR-mutant cells. Furthermore, WNT5A inhibited β-catenin activity and the transcriptional levels of its downstream genes in cancer progression.Conclusions: Our research revealed the role of WNT5A in NSCLC BM with EGFR mutation and proved that E2F1-mediated repression of WNT5A was dependent on the ERK1/2 pathway, supporting the notion that targeting the ERK1/2-E2F1-WNT5A pathway could be an effective strategy for treating BM in EGFR-mutant NSCLC.