To better understand the mechanism(s) underlying lung cancer invasion and metastasis, a Transwell invasion chamber was used to select progressively more invasive cancer cell populations from a clonal cell line of human lung adenocarcinoma, CL1. Five sublines with progressive invasiveness, designated CL1-1, CL1-2, CL1-3, CL1-4, and CL1-5, were obtained through this in vitro selection process. Their invasive abilities through basement membrane matrix showed a 4- to 6-fold increase over that of the parental cells. Moreover, the sublines manifested an increase in their colony-forming ability on soft agar, tumorigenicity, and metastatic potency in severe combined immunodeficiency (SCID) mice. Examining the phenotypes of the cell lines revealed increased expression of 92 kD gelatinase and an increase in the cell population stained with anti-keratin-8 and -18 antibodies. Clonal isolation of anti-keratin-18-antibody-positive and -negative cell populations demonstrated a correlated enhancement of the invasiveness of these cells and their expression of keratin-18. These results support the notion that the metastatic behavior of lung cancer cells can be characterized with this in vitro system, and that the properties of these progressively invasive cancer cells can be clonally studied.

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Dysregulation of microRNAs has a critical role in cancer progression. Here we identify an intronic microRNA, miR-135b that is upregulated in highly invasive non-small-cell lung cancer cells. Expression of miR-135b enhances cancer cell invasive and migratory abilities in vitro and promotes cancer metastasis in vivo, while specific inhibition of miR-135b by a miR-135b-specific molecular sponge and antagomirs suppresses cancer cell invasion, orthotopic lung tumour growth and metastasis in a mouse model. miR-135b targets multiple key components in the Hippo pathway, including LATS2, b-TrCP and NDR2, as well as LZTS1. Expression of miR-135b, LZTS1, LATS2 and nuclear TAZ predicts poor outcomes of non-small-cell lung cancer. We find that miR-135b is dually regulated by DNA demethylation and nuclear factor-kappaB signalling, implying that abnormal expression of miR-135b in cancer may result from inflammatory and epigenetic modulations. We conclude that miR-135b is an oncogenic microRNA and a potential therapeutic target for non-small-cell lung cancer.

Purpose: In a previous genome-wide gene expression profiling analysis using an invasion cancer cell lines model, we have identified Slug as selectively overexpressed in the highly invasive cancer cells. Here, we investigated the clinical significance of Slug in lung adenocarcinoma and the role of Slug in the process of cancer cell invasion and metastasis. Experimental Design: Real-time quantitative reverse transcription-PCR was used to investigate Slug mRNA in surgically resected lung adenocarcinoma of 54 patients and its correlation with survival.We overexpressed Slug in a lung adenocarcinoma cell line with very low Slug levels and investigated the in vitro and in vivo effects of Slug expression. Results: High expression of Slug mRNA in lung cancer tissue was significantly associated with postoperative relapse (P = 0.03) and shorter patient survival (P < 0.001). The overexpression of Slug enhanced xenograft tumor growth and increased microvessel counts in angiogenesis assay. Both inducible and constitutive overexpression of Slug suppressed the expression of E-cadherin and increased the in vitro invasive ability. Zymography revealed increased matrix metalloproteinase-2 activity in Slug overexpressed cells. ELISA, reverse transcription-PCR, and immunohistochemistry confirmed the increase of matrix metalloproteinase-2 proteins and mRNA in Slug overexpressed cells and xenograft tumors. Conclusions: Slug expression can predict the clinical outcome of lung adenocarcinoma patients. Slug is a novel invasion-promoting gene in lung adenocarcinoma.Lung cancer is the leading cause of cancer death worldwide.Metastasis is the most common cause of death in lung cancer patients and is a major obstacle to the successful treatment. The spread of tumor cells from a primary tumor to the secondary sites within the body is a complicated process involving cell proliferation and migration, degradation of basement membrane, invasion, adhesion, and angiogenesis (1). A variety of positive and negative factors are involved in this highly sophisticated process of metastasis (2). Current clinical means cannot accurately identify those patients who will develop metastasis. To develop effective new strategies for the prediction, diagnosis, and treatment of metastasis of lung cancer, molecular mechanisms controlling metastasis must be identified (3).Cancers are a mass of heterogeneous neoplastic cells with different properties, including metastatic potential (4). During cancer development, some tumor cells acquire metastatic phenotypes, overexpression of metastasis-promoting genes or loss of expression of metastasis-suppressing genes. Recently, several groups have successfully used gene expression profiling techniques and model systems with different invasive or metastatic ability to identify genes that correlate with invasiveness or metastatic potential (5 -9).Multiple rounds of in vitro and in vivo selection of subclones of cancer cells originating from the same primary lung adenocarcinoma may result in the establishment of several ...

NRP1 is a cancer invasion and angiogenesis enhancer. NRP1 expression is an independent predictor of cancer relapse and poor survival in NSCLC patients. NRP1 plays a critical role in tumorigenesis, cancer invasion, and angiogenesis through VEGF, PI3K, and Akt pathways. NRP1 may have potential as a new therapeutic target in NSCLC.