BackgroundCD73 (ecto-5′-nucleotidase) is implicated in the development of many types of cancer. CD73 inhibitors are currently being tested in clinical trials for the treatment of cancer. Understanding the molecular and cellular actions of CD73 inhibitors is the key to improving this line of therapy.MethodsQuantitative real-time PCR (qRT-PCR) was used to detect the expression of CD73 and miR-30a-5p; Western blot and immunohistochemical assays were used to investigate the levels of CD73 and other proteins. Flow cytometry was used to determine cell cycle stage and apoptosis. CCK-8 and clonogenic assays were used to investigate cell proliferation. Wound healing, migration and invasion assays were used to investigate the motility of cells. A lung carcinoma xenograft mouse model was used to investigate the in vivo effects of CD73 and miR-30a-5p.ResultsIn the present study, we found that CD73 is overexpressed and miR-30a-5p is underexpressed in non-small cell lung cancer tissues compared with adjacent noncancerous. Further, we showed that CD73 is a direct target of miR-30a-5p by luciferase reporter assays, qRT-PCR and western blot analysis. We also found that overexpression of miR-30a-5p in these non-small cell lung cancer cell lines inhibited cell proliferation in vitro and in vivo. Moreover, the epithelial-to-mesenchymal phenotype was suppressed and cell migration and invasion were inhibited; these effects were brought about via the EGF signaling pathway.ConclusionsOur findings reveal a new post-transcriptional mechanism of CD73 regulation via miR-30a-5p and EGFR-related drug resistance in non-small cell lung cancer.Electronic supplementary materialThe online version of this article (doi:10.1186/s12943-017-0591-1) contains supplementary material, which is available to authorized users.

Abstract. Lung cancer is the leading cause of cancer-related mortality worldwide and although there have been improvements in treatment there is a low survival rate. The aim of the present study was to investigate the effect of microRNA (miRNA) on cell pathways. A miRNA microarray was used to profile miRNAs of lung cancer tissues. It was identified that 33 miRNAs with >2.0-fold change and FDR <0.05 were differentially expressed between the adjacent noncancerous lung tissues and non-small cell lung cancers NSCLCs (P<0.005). The data were optimized in combination with physical interaction analysis to obtain crucial miRNAs. The results showed that differentially expressed miRNAs were associated with biological processes such as cell migration, protein phosphorylation and neuron differentiation, and signaling pathways such as MAPK, TGF-β and PI3K/ Akt signaling pathways. Validation of significant miRNAs in independent 40 paired NSCLC tissues demonstrated that the expression level of miR-486-5p and miR-30a-5p was significantly downregulated in another 40 paired lung cancer tissues. Taken together, the results provided strong evidence of the possible involvement of miRNAs in the development and progression of NSCLC. Thus, the results are of importance for clinical investigators and for those who design miRNA-based novel cancer therapeutics.

The TGF-β/Smad signaling pathway plays important roles in cancer cell proliferation, apoptosis, differentiation, angiogenesis and epithelial-mesenchymal transition (EMT), which is the key event in the early stages of cancer metastasis and enhances the capability of cell migration and invasion. Smad4 acts as the only Co-Smad of TGF/Smad signaling pathway and plays the key role in TGF-β-mediated EMT. Nevertheless, the mRNA regulation mechanisms of Smad4 in human non-small cell lung cancer (NSCLC) remains largely unclear. Computational algorithms predicted that the 3'-UTR of Smad4 is a target of miR‑205. Here, we validated that miR‑205 could directly bind to 3'-UTR of Smad4 by luciferase assays. Moreover, we investigated the functional roles of miR‑205 and its molecular link to Smad4 in lung cancer cells. In this study, we confirmed that overexpression of miR‑205 suppressed the expression of Smad4, in turn, weakened the TGF-β/Smad signaling pathway and inhibited TGF-β/Smad4-induced EMT, invasion and migration ultimately. Furthermore, this study shows that miR‑205 can serve as a promising therapeutic target of highly aggressive NSCLC.

Neuropilin 1 (NRP1) is a transmembrane glycoprotein that acts as a co‐receptor for multiple extracellular ligands and typically performs growth‐promoting functions in cancer cells. Accumulating evidence indicates that NRP1 is upregulated, and may be an independent predictor of cancer relapse and poor survival, in many cancer types, including non‐small cell lung cancer (NSCLC). Recent evidence suggests that NRP1 affects tumour cell viability via the epidermal growth factor receptor (EGFR) and Erb‐B2 receptor tyrosine kinase 2 (ErbB2) signalling pathways in venous endothelial cells and in multiple cancer cells. In the present study, we aimed to evaluate the role of NRP1 in NSCLC tumourigenesis and to explore a new post‐transcriptional mechanism of NRP1 regulation via a microRNA that mediates EGFR signalling regulation in lung carcinogenesis. The results showed that miR‐338‐3p is poorly expressed and NRP1 is overexpressed in NSCLC tissues relative to their levels in adjacent noncancerous tissues. Luciferase reporter assays, quantitative real‐time reverse transcription PCR, and Western blot analyses showed that NRP1 is a direct target of miR‐338‐3p. Overexpression of miR‐338‐3p in NSCLC cell lines inhibited cell proliferation in vitro and in vivo. Moreover, cell migration and invasion were inhibited by miR‐338‐3p overexpression. These effects occurred via the EGF signalling pathway. Our data revealed a new post‐transcriptional mechanism by which miR‐338‐3p directly targets NRP1; this mechanism plays a role in enhancing drug sensitivity in EGFR wild‐type patients with NSCLC.

BackgroundLung cancer is a major public health issue in most countries, including China. The expression of RelB is associated with poor prognosis in diverse cancers. However, whether RelB expression could be an indicator of poor prognosis in non‐small cell lung cancer (NSCLC) is still unclear.MethodsThe expression of RelB in NSCLC tumor tissue and adjacent non‐neoplastic tissues were examined by immunohistochemistry. Chi‐square or two‐tailed Fisher's exact tests were used to analyze possible associations between qualitative clinicopathological variables and RelB expression. Kaplan–Meier analysis and a Cox regression model were employed to determine independent prognostic factors.ResultsThe expression of RelB was increased in tumor tissue compared with adjacent non‐neoplastic tissue in NSCLC patients. High RelB expression was significantly correlated with degree of differentiation (P = 0.023), depth of tumor invasion (P < 0.001), lymph node metastasis (P = 0.017), distant metastases (P = 0.004), and tumor node metastasis stage (P < 0.001) in patients with NSCLC. NSCLC patients with high RelB expression had significantly shorter overall survival than those with low RelB expression (P < 0.001). Our results indicate that high RelB expression is an independent prognostic factor for patients with NSCLC (P < 0.001).ConclusionsHigh RelB expression could provide a basis for judgment of prognosis in patients with NSCLC.