Lung cancer is the most common malignancy worldwide. Thus, there is a critical need for diagnostic biomarkers with adequate sensitivity and specificity for lung cancer detection. Glycans in glycoproteins are significantly altered in cancer, and may serve as a tool for identifying potential diagnostic biomarkers. Recent studies have reported changes in α-1-antitrypsin (A1AT) glycosylation in lung cancer serum, tissue and cell lines. In this study, a lectin microarray was used to detect glycosylation changes in serum A1AT from patients with lung adenocarcinoma (ADC), squamous cell lung cancer, small-cell lung cancer (SCLC) and benign pulmonary diseases. Differentially expressed glycosylated patterns of A1AT were identified by lectin arrays and were confirmed by lectin-based enzyme-linked immunosorbent assay (ELISA). We found that galactosylated A1AT could distinguish non-small-cell lung cancer (NSCLC) from benign pulmonary diseases (AUC = 0.834); fucosylated A1AT showed exceptional capability in distinguishing ADC from benign diseases (AUC = 0.919) or other lung cancer subtypes (AUC = 0.844), and A1AT containing poly-LacNAc could detect SCLC from benign diseases (AUC = 0.905) or NSCLC (AUC = 0.707). The present study indicates that glycosylated patterns of A1AT may serve as potential biomarkers for detection of lung cancer. Further studies in larger sample sizes are necessary to validate the clinical utility of these markers.

MicroRNAs (miRNAs) play a critical role in cancer development and progression. Aberrant expression of miR-15a has recently been reported in several cancers, but its role in non-small cell lung cancer (NSCLC) still remains obscure. We investigated the effects of miR-15a on proliferation, apoptosis, and metastasis in A549 cells. Eighteen paired NSCLC and adjacent non-tumor lung tissues were surgically removed and immediately snap frozen until total RNA was extracted and confirmed by two independent pathologists. The targets of miR-15a were predicted by bioinformatics tools. RNA isolation and quantitative real-time PCR (qRT-PCR), Western blot analysis, cell proliferation assay, cell cycle analysis, cell apoptosis assay, and migration and invasion assays were done. The wild type (WT) or mutant type (MT) 3'-untranslated region (UTR) vectors were co-transfected with miR-15a or negative control into A549 cells, and after 24 h of transfection, luciferase activity was measured using the Dual-Glo luciferase assay kit. Statistical analysis was performed using SPSS 13.0 software (SPSS, Chicago, IL, USA). P values of less than 0.05 were considered statistically significant. miR-15a was significantly downregulated in NSCLC than in adjacent non-cancerous tissues. miR-15a overexpression remarkably inhibited cell viability, invasion, and migration and promoted the apoptosis of NSCLC cells. Additionally, inhibition of miR-15a expression had the opposite effects on tumor progression, while cell cycle remained unaltered. Furthermore, we identified that BCL2L2 was a target of miR-15a and negatively regulated by miR-15a at the translational level. miR-15a acts as a tumor suppressor in NSCLC by directly targeting BCL2L2 and may serve as a potential diagnostic biomarker and therapeutic target for NSCLC.

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Lung cancer has the highest mortality rate among cancers; however, its nosogenesis is still unclear. Genome-wide association studies have shown that the telomerase reverse transcriptase (TERT) gene, located in the chromosome 5p15.33 region, is one of the genes associated with the risk of lung cancer. In this case-control study, we genotyped 11 tag single-nucleotide polymorphisms of the TERT gene to evaluate their association with lung cancer risk in the Han Chinese population. Two tag single-nucleotide polymorphisms were found to be associated with lung cancer risk on using the χ2-test: rs4246742 [odds ratio (OR)=0.77, 95% confidence interval (CI) 0.60-0.98; P=0.03] and rs2853672 (OR=1.26, 95% CI 1.01-1.57; P=0.045). By using SNPStats software we also found rs2242652 (OR=1.47, 95% CI 1.02-2.13; P=0.04) in the dominant model and rs2736098 (OR=1.38, 95% CI 1.06-1.80; P=0.017), rs2853672 (OR=1.41, 95% CI 1.11-1.80; P=0.0048), and rs4246742 (OR=0.75, 95% CI 0.58-0.97; P=0.029) in the log-additive model. 'T/C-T/T' of rs10069690 conferred an increased risk for male sex in the dominant model (OR=1.80, 95% CI, 1.05-3.08; P=0.03) and 'TC' increased risk for male sex in the overdominant model (OR=1.85, 95% CI, 1.08-3.17; P=0.031). Our findings, combined with previous studies, suggest that polymorphisms in the TERT gene contribute to the risk for lung cancer in the Chinese Han population.

Family of forkhead box transcription factors, including forkhead box P4 (FOXP4), plays an important role in oncogenesis. The current study is to evaluate the role of FOXP4 in regulating human non-small cell lung cancer (NSCLC). Quantitative RT-PCR and Western blot were performed to evaluate the gene and protein expressions of FOXP4 in six NSCLC cell lines and 55 NSCLC patients. Lentivirus of small hairpin RNA (FOXP4-shRNA) was used to downregulate FOXP4 in NSCLC cell lines A549 and H1703 cells. Its effect on NSCLC growth, invasion, and cell cycle were evaluated by cell proliferation assay, migration assay, and cell cycle assay, respectively. Dual luciferase assay and Western blot were used to examine whether microRNA-138 (miR-138) was an upstream regulator of FOXP4. The dependence of FOXP4 on miR-138 associated signaling pathway was evaluated by ectopically overexpressing enhancer of zeste homolog 2 (EZH2), a known miR-138 target in NSCLC. FOXP4 was highly expressed in both NSCLC cell lines and NSCLC patients. FOXP4 downregulation by FOXP4-shRNA markedly reduced cancer cell growth and invasion, as well as induced cell cycle arrest in A549 and H1703 cells. MiR-138 was confirmed to be an upstream regulator of FOXP4 and directly regulated FOXP4 expression in A549 and H1703 cells. FOXP4 downregulation-mediated inhibition on cancer cell growth and invasion was independent on overexpressing EZH2, another direct target of miR-138 in NSCLC. Our data demonstrated that FOXP4 was a critical regulator in NSCLC and independently associated with miR-138 regulation.