The present study aimed to investigate the expression, biological function and mechanism of action of engrailed homeobox 2 (EN2) in non-small cell lung cancer (NSCLC) at the tissue and cellular level. A total of 42 patients who underwent surgical resection of NSCLC tissues between January 2014 and January 2015 were included in the present study. EN2 mRNA expression levels in explanted NSCLC tissues were determined using reverse-transcription quantitative polymerase chain reaction analysis. Adenocarcinoma human alveolar basal epithelial A549 cells were transfected with negative control plasmids or those containing EN2, enabling its overexpression. To assess the effect of EN2 overexpression in A549 cells, a Cell Counting kit-8 assay was used to analyze cellular proliferation, a Transwell assay was used to evaluate cellular migration and invasion and flow cytometry was used to detect the cell cycle distribution. To measure protein expression of EN2 and β-catenin in A549 cells, western blotting was also conducted. EN2 mRNA expression levels in NSCLC tissues were lower than those in normal tissues, and were associated with metastasis, clinical staging and differentiation degrees of NSCLC. Increased expression of EN2 inhibited the proliferation of A549 cells , and suppressed their migration and invasion. Elevated EN2 expression inhibited the proliferation of A549 cells by regulating the G/S phase transition. β-catenin protein expression levels and nuclear translocation in A549 cells were inhibited by EN2 overexpression. The present study demonstrated that expression of EN2 in NSCLC tissues was downregulated and negatively associated with the degree of disease differentiation, lymphatic metastasis and clinical staging. Overexpression of EN2 inhibits the proliferation, migration and invasion of A549 cells, as well as the expression of β-Catenin and nuclear translocation.

Background Lung adenocarcinoma (AD) remains one of the most common cancers. Early diagnosis of AD improves therapeutic strategy and lengthens survival time. The objective of this study is to identify hub genes influencing the process of lung AD. Methods The microarray profiles of GSE43458 were extracted from the Gene Expression Omnibus (GEO) database to screen potential targets during lung AD. Differentially expressed genes (DEGs) between AD patients and normal controls were detected. Then gene ontology (GO) and Kyoto Encyclopedia of Gene and Genome (KEGG) pathway analysis were performed. Moreover, the major modules of protein-protein interaction (PPI) network of those DEGs were performed using the MCODE plug of the Cytoscape. The hub genes were validated in the Oncomine and GEPIA datasets. Additionally, the prognostic values of hub genes were evaluated in Kaplan Meier plotter and GEPIA databases. Results Totally, 859 DEGs were identified, including 278 up-regulated and 581 down-regulated genes. Functional annotation suggested those DEGs were related to cell adhesion, migration and motility. Besides, helicase lymphoid-specifics (HELLs) and selenoprotein P1 (SEPP1) were regarded as hub genes in AD. Then, the upregulation of HELLs and downregulation of SEPP1 were validated in the Oncomine and GEPIA databases, respectively. Moreover, Kaplan-Meier and GEPIA databases also suggested both HELLs and SEPP1 could affect the prognosis of lung AD patients. Conclusions Our study demonstrated HELLs and SEPP1 were hub genes contributing to the progress of lung AD. They could be potential target genes for the diagnosis and therapy of lung AD.