lncRNA EGFR-AS1 facilitates leiomyosarcoma progression and immune escape via the EGFR–MYC–PD-L1 axis
Meiling Chen, Fan Li, Guangrong Huang, Zhi-feng Sun
Abstract
AIM: this study aimed to investigate the role of long non-coding RNA (lncRNA) epidermal growth factor receptor antisense RNA 1 (EGFR-AS1), an antisense transcript of EGFR, in leiomyosarcoma (LMS) and the underlying mechanisms. METHODS: levels of EGFR-AS1 and programmed death ligand 1 (PD-L1) were measured in LMS tissues and cell lines using quantitative real-time PCR (qRT-PCR), as well as western blotting and/or immunohistochemical staining; flow cytometry was employed to validate the role of EGFR-AS1 in altering the activity of CD8+ T cells; interaction of EGFR-AS1 and EGFR was determined by fluorescent in situ hybridization (FISH) and RNA pull-down; regulation of MYC on the PD-L1 promoter was assessed by chromatin immunoprecipitation (ChIP); a xenograft in vivo tumor growth assay was applied to verify the EGFR-AS1/EGFR/MYC/PD-L1 axis in vivo. RESULTS: up-regulation of EGFR-AS1 and PD-L1 in LMS tissues was negatively correlated with CD8+ T-cell infiltration; EGFR-AS1 positively regulated PD-L1, thereby strengthening interaction of LMS cells and CD8+ T cells and triggering CD8+ T cell apoptosis via the PD-1/PD-L1 checkpoint; EGFR-AS1 co-localized and interacted with EGFR to promote MYC activity; MYC was identified as a transcriptional activator of PD-L1. CONCLUSION: lncRNA EGFR-AS1 was demonstrated to increase PD-L1 expression through the EGFR/MYC pathway in LMS cells, thereby repressing T-cell infiltration and contributing to immune escape.