MicroRNA-148a Suppresses Invasion and Metastasis of Human Non-Small-Cell Lung Cancer.

BACKGROUND/AIMS: microRNAs (miRNAs) are noncoding RNAs that regulate multiple targets through either the degradation of mRNAs or the inhibition of protein translation, thereby altering several functions simultaneously. Growing evidence indicates that miRNAs are involved in carcinogenesis and tumor progression in non-small-cell lung cancer (NSCLC). METHODS: In this study, the mRNA expression levels of miR-148a were examined in NSCLC cell lines and patient specimens using quantitative reverse transcription-PCR. The functions of miR-148a in migration/invasion and lung metastasis formation were determined by using transwell and tail vein injection assays, respectively. RESULTS: We demonstrated that miR-148a was down-regulated in NSCLC metastatic samples, and its expression was suppressed in NSCLC compared with the corresponding nonmalignant lung tissues. Clinical analysis indicated that miR-148a expression was lower in NSCLC patients compared with nonmalignant lung tissues . Decreased miR-148a was significantly associated with tumor node metastasis stage and lymph node metastasis. Furthermore, functional assays showed that miR-148a expression suppressed NSCLC cell invasive and migratory abilities in vitro and suppressed cancer metastasis in vivo, while inhibition of miR-148a enhanced NSCLC cell invasion and lung metastasis formation in a mouse model. CONCLUSIONS: Evidence from this study demonstrated that miR-148a exerts tumor-suppressive effects in NSCLC and suggests a new therapeutic option for NSCLC.

miRNA-200c inhibits invasion and metastasis of human non-small cell lung cancer by directly targeting ubiquitin specific peptidase 25.

BACKGROUND: Growing evidence indicates that miR-200c is involved in carcinogenesis and tumor progression in non-small-cell lung cancer (NSCLC). However, its precise biological role remains largely elusive. METHODS: The functions of miR-200c and USP25 in migration/invasion and lung metastasis formation were determined by transwell and tail vein injection assays, respectively. The potential regulatory targets of miR-200c were determined by prediction tools, correlation with target protein expression, and luciferase reporter assay. The mRNA expression levels of miR-200c and USP25 were examined in NSCLC cell lines and patient specimens using quantitative reverse transcription-PCR. The protein expression levels of USP25 were examined in NSCLC cell lines and patient specimens using western blot and immunohistochemical staining. RESULTS: We demonstrated that over-expression of miR-200c inhibited NSCLC cells migration, invasion, epithelial-mesenchymal transition (EMT) in vitro and lung metastasis formation in vivo. Further studies revealed that USP25 was a downstream target of miR-200c in NSCLC cells as miR-200c bound directly to the 3'-untranslated region of USP25, thus reducing both the messenger RNA and protein levels of USP25. Silencing of the USP25 gene recapitulated the effects of miR-200c over-expression. Clinical analysis indicated that miR-200c was negatively correlated with clinical stage, lymph node metastasis in NSCLC patients. Moreover, USP25 protein and mRNA level expressions were higher in NSCLC patients, compared to healthy control, and correlated with clinical stage and lymphatic node metastasis. CONCLUSIONS: These findings indicate that miR-200c exerts tumor-suppressive effects for NSCLC through the suppression of USP25 expression and suggests a new therapeutic application of miR-200c in the treatment of NSCLC.

Development of a highly metastatic model that reveals a crucial role of fibronectin in lung cancer cell migration and invasion.

BACKGROUND: The formation of metastasis is the most common cause of death in patients with lung cancer. A major implement to understand the molecular mechanisms involved in lung cancer metastasis has been the lack of suitable models to address it. In this study, we aimed at establishing a highly metastatic model of human lung cancer and characterizing its metastatic properties and underlying mechanisms. METHODS: The human lung adeno-carcinoma SPC-A-1 cell line was used as parental cells for developing of highly metastatic cells by in vivo selection in NOD/SCID mice. After three rounds of selection, a new SPC-A-1sci cell line was established from pulmonary metastatic lesions. Subsequently, the metastatic properties of this cell line were analyzed, including optical imaging of in vivo metastasis, immunofluorescence and immunohistochemical analysis of several epithelial mesenchymal transition (EMT) makers and trans-well migration and invasion assays. Finally, the functional roles of fibronectin in the invasive and metastatic potentials of SPC-A-1sci cells were determined by shRNA analysis. RESULTS: A spontaneously pulmonary metastatic model of human lung adeno-carcinoma was established in NOD/SCID mice, from which a new lung cancer cell line, designated SPC-A-1sci, was isolated. Initially, the highly metastatic behavior of this cell line was validated by optical imaging in mice models. Further analyses showed that this cell line exhibit phenotypic and molecular alterations consistent with EMT. Compared with its parent cell line SPC-A-1, SPC-A-1sci was more aggressive in vitro, including increased potentials for cell spreading, migration and invasion. Importantly, fibronectin, a mesenchymal maker of EMT, was found to be highly expressed in SPC-A-1sci cells and down-regulation of it can decrease the in vitro and in vivo metastatic abilities of this cell line. CONCLUSIONS: We have successfully established a new human lung cancer cell line with highly metastatic potentials, which is subject to EMT and possibly mediated by increased fibronectin expression. This cell line and its reproducible s.c. mouse model can further be used to identify underlying mechanisms of lung cancer metastasis.

RNA-binding protein KHSRP promotes tumor growth and metastasis in non-small cell lung cancer.

BACKGROUND: KH-type splicing regulatory protein (KHSRP) plays an important role in cancer invasion, but the relevant mechanism is not well known. In the present study, we investigated the function and potential molecular mechanism of KHSRP in non-small cell lung cancer (NSCLC) metastasis and elucidated its clinical significance. METHODS: Isobaric tags for relative and absolute quantitation and the SWATH™ approach were combined with nanoliquid chromatography-tandem mass spectrometry analysis to identify metastasis-associated nucleoproteins in NSCLC. Real-time PCR and Western blot were used to screen for metastasis-associated candidate molecules. Gene knockdown and overexpression were used to investigate their functions and molecular mechanisms in lung cancer cells. Coimmunoprecipitation (Co-IP) experiments were performed to identify the interactions between candidate molecules and their interacting proteins. Gene expression and its association with multiple clinicopathologic characteristics were analyzed by immunohistochemistry (IHC) and Western blot in human lung cancer specimens. RESULTS: KHSRP was identified as a metastasis-associated candidate molecule. In NSCLC cell lines, knockdown of KHSRP significantly reduced lung cancer cell proliferation, migration, and invasion in vitro and in vivo, whereas overexpression of KHSRP did the opposite. Mechanistically, the protein heterogeneous nuclear ribonucleoprotein C (C1/C2) (HNRNPC) was identified to interact with KHSRP using Co-IP experiments. In NSCLC cell lines, overexpression of HNRNPC significantly promoted lung cancer cell proliferation, migration, and invasion in vitro and in vivo. KHSRP and HNRNPC may induce human lung cancer cell invasion and metastasis by activating the IFN-α-JAK-STAT1 signaling pathway. Drastically higher expression levels of KHSRP and HNRNPC were observed in lung cancer tissues compared to those in adjacent noncancerous tissues. Increased KHSRP and HNRNPC expression was significantly associated with advanced tumor stages and metastasis (both lymph node and distant). Kaplan-Meier survival analysis showed that patients with high KHSRP and HNRNPC expression levels were predicted to have the shortest survival times and to have a poor prognosis. CONCLUSIONS: KHSRP plays an important role in NSCLC metastasis and may serve as a potential prognostic marker and novel therapeutic target for lung cancer metastasis treatment.

CPNE3 promotes migration and invasion in non-small cell lung cancer by interacting with RACK1 via FAK signaling activation.

Approximately 90% of patients diagnosed with non-small cell lung cancer (NSCLC) die due to distant metastases. However, the complicated molecular and cellular mechanisms involved in lung cancer metastasis remain poorly understood. Copine III (CPNE3), a member of a Ca2+-dependent phospholipid-binding protein family, was identified as a novel metastasis-associated protein in NSCLC in our previous study, however, its function in metastasis remains unclear. Here, we found that CPNE3 was expressed at high levels in NSCLC tissues and advanced TNM stages and was significantly associated with poor prognosis. In addition, CPNE3 interacted with phosphorylated erb-b2 receptor tyrosine kinase 2 (pErbB2) and receptor of activated protein C kinase 1 (RACK1) and activated the focal adhesion (FA) signaling pathway in NSCLC cells. Moreover, knockdown of RACK1 inhibited cell motility in the CPNE3-overexpressed NSCLC cells. These findings offer mechanistic insights into the oncogenic roles of CPNE3 and the pivotal effects of CPNE3 as a biomarker and therapeutic target for NSCLC metastasis.

[Establishing the nude mice bone metastasis model of lung adenocarcinoma and applying MicroCT into the observation].

BACKGROUND AND OBJECTIVE: 50%-70% of patients with advanced lung cancer will develop bone metastases. The aim of this study is to establish the nude mice bone metastasis model of lung adenocarcinoma using A549, H1299, SPC-A-1 and XL-2, all of which own different invasion and migration abilities in vitro and supervise the bone metastases by MicroCT. METHODS: fifty BALB/C-nu/nu nude mice were grouped into five groups on average randomly. Cells of the four cell lines were injected into the left cardiac ventricle of mice in the four experimental groups (0.2 mL/mouse) respectively; meanwhile, mice in the control group were injected with normal saline (0.2 mL/mouse) in the same manner. Periodical radiological examination was carried out to supervise the variation of the mice since the second week after injection. When mice in each group became thin obviously, end the experiment of this group. Before the end, pathological sections of bone tissues were made. We classified the bone metastatic sites into axial skeleton and limb bone, in order to compare the metastatic rates of these two different parts. The bone metastatic abilities of the four cell lines was statistically analyzed by comparing the average time cost in the appearance of bone metastases and the percentage of bone metastases among the experimental groups. RESULTS: Different metastatic sites which had been identified both by MicroCT and pathological sections appeared in each group of the four experimental groups. By contrast, no metastasis was observed in the control group. The percentage of cancer metastasizing to axial skeleton was remarkably higher than the percentage of tumor metastasizing to the limb bone in each experimental group, which was consistent with the clinical regularity and characteristics of skeletal metastases with lung cancer. Thus, the model has been established triumphantly. However, there were no statistical differences in the average time consumed and skeletal metastatic rate among the four experimental groups. CONCLUSIONS: The disruption in the bone can be clearly detected by MicroCT, which is benefit to supervise the osseous metastasis. We successfully developed the nude mice bone metastasis model of lung adenocarcinoma, which will pave the way for exploring novel prevention and therapy strategies clinically. The four cell lines varied in invasion and migration abilities in vitro, but there was no statistical difference in the metastatic ability in vivo, and the reason need to be explored further in future.