Clinical importance of long noncoding RNA LINC00460 expression in plasma cell-free tumor RNA in EGFR-mutant adenocarcinoma.

Abstract

e20529 Background: Long noncoding RNA (lncRNA) is longer than 200 nucleotides and does not encode proteins. The IncRNA LINC00460 was reported to be involved in physiological and pathological processes such as proliferation, invasion, metastasis, and epithelial–mesenchymal transition (EMT). However, its role in epidermal growth factor receptor ( EGFR)-mutant lung adenocarcinoma is unclear. Methods: Non–small cell lung cancer (NSCLC) cells with knockout of LINC00460 were generated with a CRISPR-Cas9 system and used to investigate the effect of LINC00460 on gefitinib-induced cell death in an MTT assay. Western blot was used to observe change in EMT-related proteins, and changes in expression of EMT-related proteins were detected with an immunofluorescence assay. In addition, among 38 EGFR mutant lung adenocarcinomas treated by EGFR-TKI, cell-free tumor RNA extracted from blood plasma samples was analyzed for LINC00460 by using a real-time PCR assay. In addition, we assessed the association between LINC00460 expression and progression-free survival (PFS) after EGFR-TKI therapy. Results: LINC00460 was up-regulated by EGFR activation. LINC00460 expressions were significantly greater in NSCLC tumors than in adjacent normal tissues (p < 0.01). H1299 cells with LINC00460 knockout were more sensitive to gefitinib. LINC00460 was induced by transcription factors such as FOS and NF-κB in EGFR-mutant lung adenocarcinoma and gefitinib-resistant cells. LINC00460 overexpression was involved in gefitinib resistance. The MTT assay showed that LINC00460 expression was greater in cells with acquired resistance to EGFR-TKIs (gefitinib, erlotinib, and osimertinib). Western blot and immunofluorescence revealed that LINC00460 expression was associated with changes in the expression of EMT-related proteins. Patients with high LINC00460 expression in plasma cell-free tumor RNA had significantly shorter PFS after EGFR-TKI therapy than did those with low expression (median PFS: 688 vs 1089 days, respectively; p = 0.024). Conclusions: LINC00460 appears to be a novel factor involved in malignant transformation of EGFR mutant–positive lung adenocarcinoma and increased EGFR-TKI resistance. LINC00460 expression in plasma cell-free tumor RNA in EGFR-mutant adenocarcinoma was associated with shorter PFS after EGFR-TKI therapy.