Tumor contains small population of cancer stem cells (CSC) that are responsible for its maintenance and relapse. Analysis of these CSCs may lead to effective prognostic and therapeutic strategies for the treatment of cancer patients. We report here the identification of CSCs from human lung cancer cells using Aldefluor assay followed by fluorescence-activated cell sorting analysis. Isolated cancer cells with relatively high aldehyde dehydrogenase 1 (ALDH1) activity display in vitro features of CSCs, including capacities for proliferation, self-renewal, and differentiation, resistance to chemotherapy, and expressing CSC surface marker CD133. In vivo experiments show that the ALDH1-positive cells could generate tumors that recapitulate the heterogeneity of the parental cancer cells. Immunohistochemical analysis of 303 clinical specimens from three independent cohorts of lung cancer patients and controls show that expression of ALDH1 is positively correlated with the stage and grade of lung tumors and related to a poor prognosis for the patients with early-stage lung cancer. ALDH1 is therefore a lung tumor stem cell-associated marker. These findings offer an important new tool for the study of lung CSCs and provide a potential prognostic factor and therapeutic target for treatment of the patients with lung cancer.

Non-small-cell lung cancer (NSCLC) is the leading cause of cancer-related death. Developing minimally invasive techniques that can diagnose NSCLC, particularly at an early stage, may improve its outcome. Using microarray platforms, we previously identified 12 microRNAs (miRNAs) the aberrant expressions of which in primary lung tumors are associated with early-stage NSCLC. Here, we extend our previous research by investigating whether the miRNAs could be used as potential plasma biomarkers for NSCLC. We initially validated expressions of the miRNAs in paired lung tumor tissues and plasma specimens from 28 stage I NSCLC patients by real-time quantitative reverse transcription PCR, and then evaluated diagnostic value of the plasma miRNAs in a cohort of 58 NSCLC patients and 29 healthy individuals. The altered miRNA expressions were reproducibly confirmed in the tumor tissues. The miRNAs were stably present and reliably measurable in plasma. Of the 12 miRNAs, five displayed significant concordance of the expression levels in plasma and the corresponding tumor tissues (all r>0.850, all P<0.05). A logistic regression model with the best prediction was defined on the basis of the four genes (miRNA-21, -126, -210, and 486-5p), yielding 86.22% sensitivity and 96.55% specificity in distinguishing NSCLC patients from the healthy controls. Furthermore, the panel of miRNAs produced 73.33% sensitivity and 96.55% specificity in identifying stage I NSCLC patients. In addition, the genes have higher sensitivity (91.67%) in diagnosis of lung adenocarcinomas compared with squamous cell carcinomas (82.35%) (P<0.05). Altered expressions of the miRNAs in plasma would provide potential blood-based biomarkers for NSCLC.

BackgroundPim-1 kinase is a proto-oncogene and its dysregulation contributes to tumorigenesis and progression of a variety of malignancies. Pim-1 was suggested as a therapeutic target of cancers. The functional relevance of Pim-1 and the mechanism underlying its dysregulation in lung tumorigenesis remained unclear. This study aimed to investigate if Pim-1 has important functions in non-small-cell lung cancer (NSCLC) by: 1) evaluating the clinicopathologic significance of Pim-1 through analysing its expression in 101 human NSCLCs tissues using quantitative PCR, Western Blot and immunohistochemical studies, 2) determining its role in NSCLC and drug resistance using in vitro assays, and 3) investigating the regulatory mechanism of Pim-1 dysregulation in lung tumorigenesis.ResultsPim-1 was upregulated in 66.2% of the lung tumor tissues and its expression was significantly related to advanced stage (P = 0.019) and lymph node metastasis (P = 0.026). Reduced Pim-1 expression suppressed NSCLC cell growth, cell cycle progression and migration in vitro. Pim-1 was a novel target of miR-486-5p determined by luciferase report assay, and ectopic miR-486-5p expression in cancer cells reduced Pim-1 expression. Furthermore, eukaryotic translation initiation factor 4E (eIF4E) controlled the synthesis of Pim-1 in NSCLC cells, and its expression was positively associated with that of Pim-1 in NSCLC tissue specimens (r = 0.504, p < 0.001). The downregulated miR-486-5p and upregulated eIF4E in NSCLC cells led to the overexpression of Pim-1 by relieving the inhibitory effect of the 3′-UTR or 5′-UTR of Pim-1 mRNA, respectively. Moreover, Pim-1 knockdown sensitized NSCLC cells to cisplatin and EGFR tyrosine kinase inhibitor, gefitinib.ConclusionsPim-1 kinase could be a critical survival signaling factor in NSCLC, and regulated by miR-486-5p and eIF4E. Pim-1 kinase may provide a potential target for diagnosis and treatment for lung cancer.Electronic supplementary materialThe online version of this article (doi:10.1186/1476-4598-13-240) contains supplementary material, which is available to authorized users.