The 1q21.3 region driver gene EFNA3 promotes disease progression via inhibition of lung adenocarcinoma cell apoptosis

Background: Lung adenocarcinoma (LUAD) is the leading cause of cancer deaths in the world. Therefore, it is necessary to explore the underlying mechanism of EFNA3 (a 1q21.3 region driver gene) in the progression of LUAD cells. Methods: Differentially-expressed genes (DEGs) in LUAD tissues were screened based on The Cancer Genome Atlas (TCGA) database. The gene copy number variations in the 1q21.3 region were clarified by copy number variation analysis. Genes associated with overall survival (OS) were identified by Kaplan Meier (KM) analysis. The intersection of the genes was used to obtain the driver genes. LUAD patients were grouped with driver gene expression, and the DEGs were identified. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis was used to identify the enrichment pathways of the driver genes. EFNA3 was knocked down using lentiviral infection in A549 and PC9 cell lines. The efficiencies of lentiviral infection were confirmed by RT-PCR (reverse transcription polymerase chain reaction). After EFNA3 knockdown, changes in cell viability were confirmed by the 3-(4,5-dimethylthiazol-2-yl)-2,5diphenyltetrazolium bromide (MTT) assay, changes in cell proliferation and apoptosis were confirmed by enzyme-linked immunosorbent assay (ELISA), while changes in the expression of apoptosis-related proteins (Bax and caspase 3) were confirmed by RT-PCR and western blot. Results: A total of 483 LUAD samples and 59 normal control samples were obtained from TCGA database, and 640 upregulated genes were identified. 154 genes with a coefficient of copy number variations greater than 10% in the 1q23.1 region and 1,247 genes that were significantly associated with patient OS were selected. The intersection results indicated that EFNA3 might be a driver gene of LUAD. KEGG enrichment analysis indicated that the DEGs were mainly enriched in apoptosis-related pathways. Cell experiments showed that after lentiviral knockdown of EFNA3, EFNA3 messenger RNA (mRNA) and protein expression was significantly reduced (P<0.05), cell viability was markedly reduced (P<0.05), LUAD cell apoptosis increased notably (P<0.05), and LUAD cell proliferation decreased significantly (P<0.05). After EFNA3 knockdown, the expression of apoptosis-related proteins (Bax and caspase3) and mRNA in LUAD cells increased markedly (P<0.05). Conclusions: As a driver gene in the progression of LUAD, EFNA3 mainly affects the progression of LUAD by regulating LUAD cell apoptosis.