Invasion Of Lung Adenocarcinoma Cells Research Articles

MiR-373-3p Promotes Invasion and Metastasis of Lung Adenocarcinoma Cells

背景与目的肺癌位居全球癌症相关死亡率的首位，其中肿瘤转移是导致肺癌患者死亡的主要原因，研究表明miR-373与多种肿瘤细胞的侵袭转移有密切关系。本研究旨在探讨miR-373-3p在非小细胞肺癌(non-small cell lung cancer, NSCLC)中的表达情况及其对肺腺癌细胞侵袭转移能力的影响。方法利用qRT-PCR法检测miR-373-3p在NSCLC组织和肺腺癌细胞株中的表达。瞬时转染hsa-miR-373-3p的mimics和inhibitor至肺腺癌H1299和A549细胞株中，利用Transwell小室检测转染后肺腺癌细胞侵袭转移能力的改变，Western blot检测转染后肺腺癌细胞中基质金属蛋白酶-9(matrix metalloproteinase-9, MMP-9)及MMP-14蛋白水平的改变。结果miR-373-3p在51例NSCLC组织和5种肺腺癌细胞株中均明显高表达。在miR-373-3p低表达的H1299细胞中过表达miR-373-3p，细胞的侵袭转移能力明显提高，同时MMP-9及MMP-14的表达上调；在miR-373-3p高表达的A549细胞中抑制miR-373-3p表达，细胞的侵袭转移能力下降，并且下调MMP-9和MMP-14的表达。结论miR-373-3p可能通过正向调节MMP-9、MMP-14的表达而促进肺腺癌细胞的侵袭转移能力。

Upregulation of SOX9 promotes cell proliferation, migration and invasion in lung adenocarcinoma.

Sex determining region Y-box 9 (SOX9) is an important transcription factor in development and has been implicated in several types of cancer. Although the association between upregulation of SOX9 and lung adenocarcinoma (ADC) has been reported previously, the role of SOX9 in the proliferation, migration and invasion of cancer cells remains unclear. Therefore, in the present study, SOX9 expression was detected in 163 human lung adenocarcinoma tissues by immunohistochemistry and western blotting. It was found that the SOX9 protein was over-expressed in the majority of lung adenocarcinoma. The full-length human SOX9 plasmid was then transfected into the lung ADC A549 cell line. An MTT assay was used to investigate the role of SOX9 in cell proliferation. Scratch and extracellular matrix cell invasion assays were performed to investigate whether SOX9 promotes the migration and invasion of lung ADC cells. The results revealed that ectopic overexpression of SOX9 in the lung adenocarcinoma cell line resulted in a marked increase in cell proliferation, migration and invasion. Accordingly, knockdown of SOX9 by RNA interference resulted in the inhibition of cell growth, migration and invasion. The present data indicate that SOX9 may act as a novel marker for lung adenocarcinoma and perform an important role in cell proliferation, migration and invasion.

USP22 promotes tumor progression and induces epithelial-mesenchymal transition in lung adenocarcinoma.

Our previous study showed that USP22 as an oncogene may mediate cancer development and progression in NSCLC, but the underlying molecular mechanism remains uncharacterized. Epithelial-mesenchymal transition (EMT) has been reported to play an important role in migration and invasion of the tumor cells. Thus, this study aims to determine the clinical significance and the possible roles of USP22 in EMT and progression of lung adenocarcinoma. Immunohistochemistry was used to determine the expression of USP22 in clinical samples. The clinical correlations and prognostic significance of the aberrantly expressed proteins were evaluated by statistical analysis. Moreover, we evaluated whether USP22 could induce EMT in cultured lung cancer cells. The USP22 expression was positive in 76.03% of specimens and was correlated with advanced clinicopathologic classifications (differentiation, T and AJCC stages) and TGF-β1 expression (p=0.008). Multivariate Cox regression analysis revealed that USP22 expression level was an independent prognostic factor for both overall survival and disease-free survival (HR, 2.060; p=0.013 and HR, 1.993; p=0.016). In vitro study revealed that USP22 can regulate proliferation and invasive properties, and induce EMT of lung adenocarcinoma cells. Moreover, USP22 may up-regulate TGF-β1 expression. Our data indicated that USP22 may promote lung adenocarcinoma cell invasion by the induction of EMT.

Knockdown of MMP12 inhibits the growth and invasion of lung adenocarcinoma cells.

Matrix metalloproteinase-12 (MMP12) is involved in many pathological processes including cancer. The expression and function of MMP12 in lung adenocarcinoma (LAC) remain unclear. The present study aimed to investigate the correlation of MMP12 expression with LAC patients and clarify its role in growth and invasion of LAC cells. The expression of MMP12 in human LAC was examined by immunohistochemical assay using a tissue microarray procedure. A loss-of-function experiment was used for observing the effects of lentiviral vector-mediated MMP12 shRNA (shMMP12) on cell growth and invasion in LAC cell lines (A549), indicated by MTT and Transwell assays. We found that the expression of MMP12 protein was significantly increased in LAC tissues compared with that in adjacent non-cancerous tissues (ANCT) (57.69% vs. 32.69%, P = 0.019), and was closely correlated with the pathological stage and lymph node metastasis of LAC patients (P = 0.01; P = 0.003). Knockdown of MMP12 inhibited proliferation and invasion of LAC cells followed by the downregulation of proliferating cell nuclear antigen (PCNA) and vascular endothelial growth factor (VEGF). In conclusion, our findings show that high expression of MMP12 is correlated with the pathological stage and tumor metastasis of LAC patients, and knockdown of MMP12 suppresses the development of LAC cells, suggesting that MMP12 may be a promising therapeutic target for the treatment of LAC.

Knockdown of PTTG1 inhibits the growth and invasion of lung adenocarcinoma cells through regulation of TGFB1/SMAD3 signaling.

Increased expression of pituitary tumor-transforming gene 1 (PTTG1) is expressed in many tumors and regulates tumor growth and progression. However, the precise function of PTTG1 in the tumorigenesis of lung adenocarcinoma (LAC) is not defined yet. Here, we examined the expression of PTTG1 in human LAC tissues by immunohistochemical assay using a tissue microarray procedure. A loss-of-function experiment was carried out to investigate the effects of lentiviral vector-mediated PTTG1 shRNA (shPTTG1) on cell growth and invasive potential in LAC cell lines (A549 and LETPα-2), assessed by MTT and Transwell assays. As a consequence, we found that the expression of PTTG1 protein was markedly upregulated in LAC tissues compared with the adjacent non-cancerous tissues (ANCT) (54.0% vs. 28.0%, P = 0.008), and was positively associated with the lymphatic invasion of the tumor (P = 0.01). Moreover, knockdown of PTTG1 expression inhibited tumor proliferation and invasion of LAC cells, companied by the decreased expression of CyclinD1 and MMP-2 and increased expression of p-TGFβ1 and p-SMAD3. Collectively, our findings indicate that high expression of PTTG1 is correlated with the tumor metastasis of LAC patients, and knockdown of PTTG1 suppresses the growth and invasion of LAC cells through upregulation of the TGFβ1/SMAD3 signaling, suggesting that PTTG1 may be a potential target for developing an effective immunotherapeutic strategy for LAC.

17-AAG suppresses growth and invasion of lung adenocarcinoma cells via regulation of the LATS1/YAP pathway.

The large tumour suppressor 1 (LATS1) signalling network has been proved to be an essential regulator within the cell, participating in multiple cellular phenotypes. However, it is unclear concerning the clinical significance of LATS1 and the regulatory mechanisms of 17-Allylamino-17- demethoxygeldanamycin (17-AAG) in lung adenocarcinoma (LAC). The aim of the present study was to investigate the correlation of LATS1 and yes-associated protein (YAP) expression with clinicopathological characteristics in LAC patients, and the effects of 17-AAG on biological behaviours of LAC cells. Subcutaneous LAC tumour models were further established to observe the tumour growth in nude mice. The results showed that the positive expression of LATS1 was significantly lowered (26.7% versus 68.0%, P < 0.001), while that of YAP was elevated (76.0% versus 56.0%, P + 0.03) in LAC tissues compared to the adjacent non-cancerous tissues; LAST1 expression was negatively correlated with YAP expression (r + 0.432, P < 0.001) and lymphatic invasion of the tumour (P + 0.015). In addition, 17-AAG inhibited proliferation and invasion, and induced cell apoptosis and cycle arrest in LAC cells together with increased expression of E-cadherin and p-LATS1, and decreased expression of YAP and connective tissue growth factor. Tumour volumes and weight were much smaller in 17-AAG-treated groups than those in untreated group (P < 0.01). Taken together, our findings indicate that decreased expression of LATS1 is associated with lymphatic invasion of LAC, and 17-AAG suppresses growth and invasion of LAC cells via regulation of the LATS1/YAP pathway in vitro and in vivo, suggesting that we may provide a promising therapeutic strategy for the treatment of human LAC.

LAMC2 enhances the metastatic potential of lung adenocarcinoma.

Lung cancer is the number one cancer killer, and metastasis is the main cause of high mortality in lung cancer patients. However, mechanisms underlying the development of lung cancer metastasis remain unknown. Using genome-wide transcriptional analysis in an experimental metastasis model, we identified laminin γ2 (LAMC2), an epithelial basement membrane protein, to be significantly upregulated in lung adenocarcinoma metastatic cells. Elevated LAMC2 increased traction force, migration, and invasion of lung adenocarcinoma cells accompanied by the induction of epithelial-mesenchymal transition (EMT). LAMC2 knockdown decreased traction force, migration, and invasion accompanied by EMT reduction in vitro, and attenuated metastasis in mice. LAMC2 promoted migration and invasion via EMT that was integrin β1- and ZEB1-dependent. High LAMC2 was significantly correlated with the mesenchymal marker vimentin expression in lung adenocarcinomas, and with higher risk of recurrence or death in patients with lung adenocarcinoma. We suggest that LAMC2 promotes metastasis in lung adenocarcinoma via EMT and may be a potential therapeutic target.

FOXM1 promotes lung adenocarcinoma invasion and metastasis by upregulating SNAIL.

The forkhead box M1 (FOXM1) transcription factor is one of the key genes inducing tumor invasion and metastasis by an unknown mechanism. In this study, we set out to investigate the effects of FOXM1 overexpression on metastatic human lung adenocarcinoma and the underlying mechanism. FOXM1 expression was analyzed in 78 frozen lung adenocarcinoma tissue samples using an Affymetrix microarray and a 155-paraffin-embedded lung adenocarcinoma tissue microarray with immunohistochemical detection. FOXM1 was found to be overexpressed in lung adenocarcinoma, particularly in metastatic patients, compared to non-metastatic patients. Knockdown of FOXM1 by a specific siRNA significantly suppressed EMT progression, migration and invasion of lung adenocarcinoma cells in vitro, and tumor growth and metastasis in vivo, whereas restored expression of FOXM1 had the opposite effect. FOXM1 binds directly to the SNAIL promoter through two specific binding sites and constitutively transactivates it. Collectively, our findings indicate that FOXM1 may play an important role in advancing lung adenocarcinoma progression. Aberrant FOXM1 expression directly and constitutively activates SNAIL, thereby promoting lung adenocarcinoma metastasis. Inhibition of FOXM1-SNAIL signaling may present an ideal target for future treatment.

MicroRNA-29a suppresses the growth, migration, and invasion of lung adenocarcinoma cells by targeting carcinoembryonic antigen-related cell adhesion molecule 6

Carcinoembryonic antigen-related cell adhesion molecule 6 (CEACAM6) is an important regulator of cell adhesion, invasion, and metastasis. The aim of this study was to evaluate the functional roles of CEACAM6 in lung adenocarcinoma and to identify miRNAs that inhibit the growth, migration, and invasion of lung adenocarcinoma cells by targeting CEACAM6. CEACAM6 expression is associated with poor prognosis of patients with lung adenocarcinoma, and CEACAM6 has important functional roles in controlling the growth, migration, and invasion of lung adenocarcinoma cells in vitro and in vivo. Furthermore, miR-29a can suppress the growth, migration, and invasion of lung adenocarcinoma cells by targeting CEACAM6. Therefore, miR-29a/CEACAM6 axis represents a potential therapeutic target for treatment of lung adenocarcinoma.

Benzo(a)pyrene promotes A549 cell migration and invasion through up-regulating Twist.

Benzo(a)pyrene (BaP) is one of the strongest carcinogens in cigarette smoke, which is an established human carcinogen. Twist, a transcription factor of the basic helix-loop-helix class, is reported to regulate lung cancer metastasis. Evidence has shown that BaP could induce Twist mRNA expression in non-small cell lung cancer (NSCLC) cell line A549 and promote lung adenocarcinoma cell invasion. However, it is unclear whether BaP promotes the migration and invasion of NSCLC cells by Twist modulation. A549 cell was exposed to BaP for different time. MTT assay was applied to assess cell proliferation. Silencing of Twist was done by small interfering RNA. Wound-healing assay was used to evaluate the capability of cell migration. Transwell assay was used to detect the capability of cell invasion. Western blotting and quantitative polymerase chain reaction were used to detect Twist expression. The levels of Twist protein expression and mRNA expression were increased with the treatment of BaP, compared with solvent control. The capability of wound healing of A549 cells was increased in BaP-treated group, compared with solvent control. BaP enhanced the capability of invasion of A549 cells. Twist knockdown could block the migration and invasion of A549 cells induced by BaP treatment. The mRNA levels of Twist were higher in metastatic NSCLC tissue samples than in primary NSCLC tissue samples, and higher levels of Twist mRNA were observed in metastatic NSCLC tissue samples with smoking history than in those with nonsmoking history. BaP treatment could promote the migration and invasion of NSCLC cells by up-regulating Twist expression.

The MZF1/c-MYC axis mediates lung adenocarcinoma progression caused by wild-type lkb1 loss.

Liver kinase B1 (LKB1) loss in lung adenocarcinoma is commonly caused by genetic mutations, but these mutations rarely occur in Asian patients. We recently reported wild-type LKB1 loss via the alteration of NKX2-1/p53-axis-promoted tumor aggressiveness and predicted poor outcomes in cases of lung adenocarcinoma. The mechanistic action of wild-type LKB1 loss within tumor progression remains unknown. The suppression of MYC by LKB1 controls epithelial organization; therefore, we hypothesize that MYC expression can be increased via wild-type LKB1 loss and promotes tumor progression. Here, MYC transcription is upregulated by LKB1-loss-mediated MZF1 expression. The wild-type LKB1-loss-mediated MZF1/MYC axis is responsible for soft-agar growth, migrationand invasion in lung adenocarcinoma cells. Moreover, wild-type LKB1 loss-induced cell invasiveness was markedly suppressed by MYC inhibitors (10058-F4 and JQ1). Patients with low-LKB1/high-MZF1 or low-LKB1/high-MYC tumors have shorter overall survival and relapse-free-survival periods than patients with high-LKB1/low-MZF1 or high-LKB1/low-MYCtumors. In summary, MZF1-mediated MYC expression may promote tumor progression, resulting in poor outcomes in cases of lung adenocarcinoma with low-wild-type-LKB1 tumors.

Metformin inhibits the IL-6-induced epithelial-mesenchymal transition and lung adenocarcinoma growth and metastasis.

ObjectiveEpithelial-mesenchymal transition (EMT) plays an important role in cancer tumorigenesis. However, the underlying mechanisms of EMT in lung adenocarcinoma, and how this process might be inhibited, remain to be explored. This study investigated the role of IL-6 in lung adenocarcinoma cell EMT and explored the potential effects of metformin on this process.MethodsInvasion assay and MTT assay was performed to determine cell invasion and cell proliferation. Western blotting, immunofluorescence, real-time PCR, ELISA, and immunohistochemistry were performed to detect the expression of IL-6, E-cadherin, Vimentin, and p-STAT3.ResultsWe discovered that IL-6, via STAT3 phosphorylation, could promote lung adenocarcinoma cell invasion via EMT in vitro. This was supported by the inverse correlation between E-cadherin and IL-6 expression, positive correlation between IL-6 and vimentin mRNA expression and between STAT3 phosphorylation and IL-6 expression in tumor tissues. Importantly, metformin inhibited tumor growth and distant metastases in tumor-bearing nude mice and reversed IL-6-induced EMT both in vitro and in vivo. Furthermore, we found that blockade of STAT3 phosphorylation might be the underlying mechanism of metformin inhibition of IL-6-induced EMT.ConclusionsCollectively, our present results show that enhanced IL-6 expression, via STAT3 phosphorylation, is a mechanism of EMT in lung adenocarcinoma. We found that metformin could inhibit IL-6-induced EMT possibly by blocking STAT3 phosphorylation.

37-kDa laminin receptor precursor promotes lung adenocarcinoma cell invasion and metastasis by epithelial-to-mesenchymal transition.

37-kDa laminin receptor precursor (37LRP) has a crucial role in migration of some human cancers. Epithelial-to-mesenchymal transition (EMT) has received much attention in invasion and metastasis of lung cancer. Nevertheless, the role of 37LRP is not entirely clear in EMT promotion of lung cancer at present. In this study, we firstly examined the possible role of 37LRP in the invasiveness and metastasis process of lung cancer using immunohistochemistry of 80 lung adenocarcinoma cases, western blot and real-time PCR of 12 fresh lung adenocarcinoma tissues. The results showed that 37LRP significantly correlated with clinical stage and were highly expressed in metastatic lung adenocarcinomas compared with nonmetastatic ones. In vitro, we observed that 37LRP significantly increased the adhesive, invasive and metastatic abilities of human lung adenocarcinoma cell lines A549 by 37LRP-lentivirus interference. Furthermore, inoculation of A549 cells transduced with 37LRP-lentivirus in nude mice resulted in multi-metastases including the lung. In addition, western blotting and immunofluorescence were used to detect the significant difference in expression of E-cadherin and fibronectin in A549 by 37LRP-lentivirus interference compared with 37LRP-small interference RNA-lentivirus interference in vitro and vivo. The data indicated that A549 cells of epithelial cell characteristics might be induced to undergo EMT by 37LRP. A549 cells transduced with 37LRP-lentivirus showed marked morphological changes, accompanied by the decrease of epithelial marker E-cadherin and the increase of mesenchymal marker fibronectin. These results indicated that 37LRP may promote lung adenocarcinoma invasion and metastasis via the mechanism of EMT.

Enhanced invasion of lung adenocarcinoma cells after co-culture with THP-1-derived macrophages via the induction of EMT by IL-6

Lung cancer is the leading cause of cancer mortality worldwide, and the cause of death is metastasis. The epithelial-to-mesenchymal transition (EMT) plays a key role in the process of metastasis. Macrophages within the lung cancer microenvironment release cytokines, such as interleukin-6 (IL-6), and promote lung cancer cell invasion and metastasis. However, the interaction between macrophages and lung cancer cells and the effect of this interaction on the expression of IL-6, EMT, and the invasiveness of lung cancer cells remain unclear. Therefore, we established an in vitro co-culture model of human lung adenocarcinoma A549 or H1299 cells with THP-1-derived macrophages to illuminate the important role of macrophages in the invasion of lung cancer. In this study, we demonstrated that the concentrations of IL-6 in the co-culture supernatants were significantly increased compared with controls. Thus, a complex chemical cross-talk is induced by the indirect cell-to-cell contact between lung cancer cells and THP-1-derived macrophages. THP-1-derived macrophages appeared to play an important initiator role in the process. The analysis of the mRNA expression profiles of the sorted cells from the co-culture system revealed that the co-cultured lung cancer cells are the main source of the observed increase in IL-6 secretion. In addition, the interactions between lung cancer cells and THP-1-derived macrophages are bidirectional. The THP-1-derived macrophages underwent differentiation towards the M2-macrophage phenotype during the co-culture process. The expression of IL-6 was correlated with the induction of EMT, which contributed to a significant increase in the invasiveness of the A549 and H1299 cells in vitro. In addition, the addition of an anti-IL-6 antibody reversed these changes. In summary, we demonstrated that the in vitro co-culture of A549 or H1299 cells with THP-1-derived macrophages upregulates IL-6 expression, which increases the invasion ability of the A549 and H1299 cells through the EMT pathway. The THP-1-derived macrophages that interacted with the lung cancer cells differentiated towards the M2-macrophage phenotype. Thus, the inhibition of IL-6 or of the interactions between lung cancer cells and macrophages may be an effective target for anti-cancer therapy in patients with non-small cell lung cancer.

GPC5, a tumor suppressor, is regulated by miR-620 in lung adenocarcinoma

In the current study, a proportion of lung adenocarcinoma was shown to reduce GPC5 expression in the absence of transcriptional silencing of the tumor suppressor gene, GPC5, by aberrant methylation of CpG islands. It was hypothesized that the loss of GPC5 expression is associated with upregulation of miR‑620 in human lung adenocarcinoma tissue compared with the matched normal lung tissue. The downregulation of GPC5 in lung adenocarcinoma cell lines is regulated by miR‑620 through binding of the 3'‑untranslated region. Furthermore, blockage of miR‑620 inhibited the proliferation, migration and invasion of lung adenocarcinoma cells by directly regulating GPC5, and GPC5 knockdown eliminates this phenotype. These results provided a novel insight into the mechanism of miRNA regulation in lung adenocarcinoma.

MicroRNA-409-3p Functions as a Tumor Suppressor in Human Lung Adenocarcinoma by Targeting c-Met

Background/Aims: Dysregulation of microRNAs is correlated with tumor development. The aim of this study is to investigate the clinicopathologic and prognostic significance of microRNA (miR)-409-3p and its tumor suppressor roles in lung adenocarcinoma (LAD). Methods: Quantitative real-time PCR (qRT-PCR) was performed to detect miR-409-3p expression in LAD tissues and corresponding noncancerous tissues. Additionally, the correlations of miR-409-3p expression with clinicopathologic factors and prognosis of patients were statistically analyzed. Next, we investigated whether miR-409-3p could function as a tumor suppressor in LAD cells via regulation of Akt signaling by targeting receptor tyrosine kinase (c-Met). Results: MiR-409-3p was significantly downregulated in LAD tissues compared with corresponding noncancerous tissues. Low miR-409-3p expression was observed to be significantly correlated with poorer tumor differentiation, advanced pTNM stage and higher incidence of lymph node metastasis. Multivariate Cox regression analyses showed that miR-409-3p expression was an independent prognostic factor for LAD patients. Functional analyses indicated that miR-409-3p could inhibit growth, induce apoptosis, reduce migration and invasion in LAD cells via inactivation of Akt signaling by targeting c-Met. Conclusions: MiR-409-3p was an independent prognostic factor and functioned as a tumor suppressor in LAD via regulation of Akt signaling by targeting c-Met.

Adenovirus Mediated Knockdown and Bone Morphogenetic Protein 2 Inhibits Human Lung Cancer Growth and Invasion In Vitro and in Vivo

Bone morphogenetic protein 2 (BMP-2) is a member of the TGF-beta superfamily of signaling molecules, and has been shown to function as a tumor suppressor involved in development and progression of many malignancies. BMP-2 has previously been reported to be closely correlated with lung cancer. But, the role and molecular mechanisms of BMP-2 in lung cancer have not yet been comprehensively explained. The present study aims to elucidate the role of BMP-2 in growth and invasion of human lung adenocarcinoma (LAC) in vitro and in vivo. Adenovirus vector-mediated BMP-2 small hairpin RNA (shBMP-2) was used to transfect into A549 LAC cells to determine the functional relevance of BMP-2 and tumor growth and invasion in vitro and in vivo, and further investigate the expression levels of BMP-2, vascular endothelial growth factor (VEGF), matrix metallopeptidase-9 (MMP-9), phosphatidylinositol 3-kinase p85alpha (PI3Kp85alpha) and phosphorylated AKT (p-AKT). As a result, LAC cell proliferation and invasion were significantly diminished by knockdown of BMP-2 indicated by MTT and Transwell assays, and cell apoptosis and cycle arrest were markedly induced indicated by flow cytometry. When BMP-2 expression was knocked down, the expression of PI3Kp85alpha, p-AKT, VEGF and MMP-9 was also down-regulated in LAC cells. In addition, the tumor volumes in LAC subcutaneous nude mouse model treated with shBMP-2 were significantly smaller than those in control and ad-GFP groups. Taken together, our findings indicate that knockdown of BMP-2 inhibits growth and invasion of LAC cells possibly via blockade of the PI3K/AKT signaling pathway, and BMP-2 may be a potential therapeutic target for lung cancer.

Sphingosine-1-phosphate receptor-3 signaling up-regulates epidermal growth factor receptor and enhances epidermal growth factor receptor-mediated carcinogenic activities in cultured lung adenocarcinoma cells

Sphingosine-1-phosphate (S1P) regulates a wide array of biological functions. However, the role of S1P signaling in tumorigenesis remains to be elucidated. In this study, we show that S1P receptor subtype 3 (S1P₃) is markedly up-regulated in a subset of lung adenocarcinoma cells compared to normal lung epithelial cells. Specific knockdown of S1P₃ receptors inhibits proliferation and anchorage-independent growth of lung adenocarcinoma cells. Mechanistically, we demonstrate that S1P₃ signaling increases epidermal growth factor receptor (EGFR) expression via the Rho kinase (ROCK) pathway in lung adenocarcinoma cells. Nuclear run-off analysis indicates that S1P/S1P₃ signaling transcriptionally increases EGFR expression. Knockdown of S1P₃ receptors diminishes the S1P-stimulated EGFR expression in lung adenocarcinoma cells. Moreover, S1P treatment greatly enhances EGF-stimulated colony formation, proliferation and invasion of lung adenocarcinoma cells. Together, these results suggest that the enhanced S1P₃-EGFR signaling axis may contribute to the tumorigenesis or progression of lung adenocarcinomas.

MiR-200 Inhibits Lung Adenocarcinoma Cell Invasion and Metastasis by Targeting Flt1/VEGFR1

The microRNA-200 (miR-200) family is part of a gene expression signature that predicts poor prognosis in lung cancer patients. In a mouse model of K-ras/p53-mutant lung adenocarcinoma, miR-200 levels are suppressed in metastasis-prone tumor cells, and forced miR-200 expression inhibits tumor growth and metastasis, but the miR-200 target genes that drive lung tumorigenesis have not been fully elucidated. Here, we scanned the genome for putative miR-200 binding sites and found them in the 3'-untranslated region (3'-UTR) of 35 genes that are amplified in human cancer. Mining of a database of resected human lung adenocarcinomas revealed that the levels of one of these genes, Flt1/VEGFR1, correlate inversely with duration of survival. Forced miR-200 expression suppressed Flt1 levels in metastasis-prone lung adenocarcinoma cells derived from K-ras/p53-mutant mice, and negatively regulated the Flt1 3'-UTR in reporter assays. Cancer-associated fibroblasts (CAFs) isolated from murine lung adenocarcinomas secreted abundant VEGF and enhanced tumor cell invasion in coculture studies. CAF-induced tumor cell invasion was abrogated by VEGF neutralization or Flt1 knockdown in tumor cells. Flt1 knockdown decreased the growth and metastasis of tumor cells in syngeneic mice. We conclude that miR-200 suppresses lung tumorigenesis by targeting Flt1.

The Role of Cancer Stroma Interaction for Invasion of Lung Adenocarcinoma Cells

PURPOSE: Clinical studies reported a good prognosis for patients with small-sized Bronchiolo-alveolar carcinoma (BAC) of the lung in which cancer cells spread on the internal surface of alveoli, but did not infiltrate interstitially. In contrast, the prognosis of patients with BAC containing actively proliferating fibroblasts is poor, with cancer cells invading frequently into micro-vessels. The importance of cancer-stroma communication for the development of the invasive component of BAC was reported previously. In this report, cancer-stroma interaction for the development of the invasive component of BAC was investigated with both in-vitro experimental model and clinical specimens.