Ability Of Lung Cancer Cells Research Articles

Cyclooxygenase-2 is associated with malignant phenotypes in human lung cancer.

The objective of the present study was to investigate whether cyclooxygenase-2 (COX-2) is associated with malignancy, and to investigate its molecular mechanisms in human lung cancer tumor malignancy. The present study used RNA interference (RNAi) methodology and celecoxib, a COX-2 inhibitor, to investigate the effect of COX-2 knockdown on the proliferation and invasion abilities of lung cancer cells and the molecular mechanisms involved. Human lung adenocarcinoma A549-si10 and LTEP-A2 cells transfected with a specific small interfering RNA (A549-si10 and LTEP-A2-si10, respectively) grew more slowly compared with parental cell lines and cells transfected with pU6. The colony formation of A549-si10 and LTEP-A2-si10 cells was also reduced. In addition, A549-si10 and LTEP-A2-si10 cells were characterized by decreased metastatic and invasive abilities. The proliferation and invasive potential of parental A549 and LTEP-A2 cells was inhibited following treatment with celecoxib. In vivo, a COX-2 knockdown resulted in a decrease of proliferation and reduction of vascular endothelial growth factor (VEGF), matrix metalloproteinase-2 (MMP-2) and endothelial growth factor receptor (EGFR) expression in A549 xenografts. In conclusion, the present study revealed that COX-2 plays a extremely important role in tumor growth, infiltration and metastasis via the regulation of VEGF, MMP-2 and EGRF expression. Therefore, COX-2 is a potential therapeutic target for lung cancer.

WSTF promotes proliferation and invasion of lung cancer cells by inducing EMT via PI3K/Akt and IL-6/STAT3 signaling pathways

Williams syndrome transcription factor (WSTF), which is encoded by the BAZ1B gene, was first identified as a hemizygously deleted gene in patients with Williams syndrome. WSTF protein has been reported to be involved in transcription, replication, chromatin remodeling and DNA damage response, and also functions as a tyrosine protein kinase. However, the function of WSTF in cancer is not known. Here, we show that WSTF overexpression promotes proliferation, colony formation, migration and invasion of lung cancer A549 and H1299 cells. WSTF overexpression also promotes tumor growth and invasive abilities of lung cancer cells in mouse xenograft models. cDNA microarray and subsequent qRT-PCR validation revealed that WSTF overexpression significantly upregulated the expression of EMT (epithelial to mesenchymal transition) marker fibronectin (FN1) and EMT-inducing genes Fos and CEACAM6. The changes of EMT markers including downregulated E-cadherin and upregulated N-cadherin and FN1 were further confirmed at both mRNA and protein levels upon WSTF overexpression, with typical morphological changes of EMT. Furthermore, WSTF activates both PI3K/Akt and IL-6/STAT3 oncogenic signaling pathways. Treatment with PI3K inhibitor ZSTK474 or STAT3 inhibitor niclosamide reversed the effects of WSTF overexpression by inhibiting cell proliferation, migration and invasion, with decreased level of p-Akt, p-STAT3 and IL-6. ZSTK474 and niclosamide also reversed EMT markers and EMT-inducing proteins including Snail, Slug, Twist and CEACAM6 in WSTF-overexpressing A549 cells. Taken together, these results demonstrate that WSTF may act as an oncoprotein in lung cancer to accelerate tumor aggressiveness by promoting EMT via activation of PI3K/Akt and IL-6/STAT3 pathways.

Repression of the autophagic response sensitises lung cancer cells to radiation and chemotherapy.

Background:The cellular autophagic response to radiation is complex. Various cells and tissues respond differentially to radiation, depending on both the dose of exposure and the time post irradiation. In the current study, we determined the autophagosomal and lysosomal response to radiation in lung cancer cell lines by evaluating the expression of the associated proteins, as well as the effect of relevant gene silencing in radio and chemosensitisation. Furthermore, tumour sensitisation was evaluated in in vivo autophagic gene silencing model after irradiation.Methods:A549 and H1299 cell lines were utilised as in vitro cancer models. Both cell lines were transfected with various small-interfering RNAs, silencing auto-lysosomal genes, and irradiated with 4 Gy. Cell growth response was evaluated with AlamarBlue assay. Western blot and confocal microscopy were utilised for the characterisation of the auto-lysosomal flux. Also, the H1299 cell line was stable transfected with small-hairpin RNA of the MAP1LC3A gene, and the tumour radiosensitisation in Athymic Nude-Foxn1nu was evaluated.Results:Following exposure to 4 Gy of radiation, A549 cells exhibited a significant induction of the autophagic flux, which was not supported by transcriptional activation of auto-lysosomal genes (LC3A, LC3B, p62, TFEB and LAMP2a), resulting in aggresome accumulation. Recovery of transcriptional activity and autophagy efficacy occurred 7 days post irradiation. Alternatively, H1299 cells, a relatively radio-resistant cell line, sharply responded with an early (at 2 days) transcriptional activation of auto-lysosomal genes that sustained an effective autophagosomal flux, resulting in adequate aggresome clearance. Subsequently, we tested the silencing of four genes (LC3A, LC3B, TFEB and LAMP2a), confirming a significant radiosensitisation and chemosensitisation to various chemotherapeutic agents, including cisplatin and taxanes. In mouse xenografts, exposure to radiation significantly reduced tumour growth (P<0.001), which was exacerbated among shLC3A-H1299 transfected tumours.Conclusions:The ability of lung cancer cells to survive after irradiation at 4 Gy depends on their ability to sustain a functional autophagic flux. Abrogation of such ability results in increased radiosensitivity and susceptibility to various chemotherapy agents. Selective inhibitors of cancer cell autophagic function may prove important for the eradication of lung cancer.

Zinc induces epithelial to mesenchymal transition in human lung cancer H460 cells via superoxide anion-dependent mechanism.

BackgroundEpithelial to mesenchymal transition (EMT) has been shown to be a crucial enhancing mechanism in the process of cancer metastasis, as it increases cancer cell capabilities to migrate, invade and survive in circulating systems. This study aimed to investigate the effect of essential element zinc on EMT characteristics in lung cancer cells.MethodsThe effect of zinc on EMT was evaluated by determining the EMT behaviors using migration, invasion and colony formation assay. EMT markers were examined by western blot analysis. Reactive oxygen species (ROS) were detected by specific fluorescence dyes and flow cytometry. All results were analyzed by ANOVA, followed by individual comparisons with post hoc test.ResultsThe present study has revealed for the first time that the zinc could induce EMT and related metastatic behaviors in lung cancer cells. Results showed that treatment of the cells with zinc resulted in the significant increase of EMT markers N-cadherin, vimentin, snail and slug and decrease of E-cadherin proteins. Zinc-treated cells exhibited the mesenchymal-like morphology and increased cancer cell motility with significant increase of activated FAK, Rac1, and RhoA. Also, tumorigenic abilities of lung cancer cells could be enhanced by zinc. Importantly, the underlying mechanism was found to be caused by the ability of zinc to generate intracellular superoxide anion. Zinc was shown to induce cellular superoxide anion generation and the up-regulation of EMT markers and the induced cell migration and invasion in zinc-treated cells could be attenuated by the treatment of MnTBAP, a specific superoxide anion inhibitor.ConclusionKnowledge gains from this study may highlight the roles of this important element in the regulation of EMT and cancer metastasis and fulfill the understanding in the area of cancer cell biology.

Pharmacogenomic Analysis of Adenylate Kinase‐4 Gene Expression Signature Identifies Withaferin‐A as an Anti‐Metastatic Agent in Non‐Small Cell Lung Cancer

Lung cancer remains the leading cause of cancer death in the world due to metastatic disseminations. So far, there are no effective therapies available to fight this fatal process. Previously, we identified adenylate kinase 4 (AK4) as a lung cancer progression marker that enhances the invasion and metastasis ability of lung cancer cells. Therefore, we queried connectivity map profiles of AK4‐associated gene expression signature and identified Withaferin‐A (WFA) as a potential agent to treat metastatic lung cancer. We found WFA potently inhibited invasion and migration of CL1‐5 and A549 cells up to 50 percent at low‐cytotoxic doses in vitro. WFA treatment also abolished the invasion activity induced by AK4 ectopic overexpression in CL1‐0 cells. Microarray analysis further revealed that differentially regulated genes upon WFA treatment were significantly enriched in gene sets annotated with cell movement and invasion of cancer cells. WFA treatment resulted in activation of stress response pathways as canonical pathway analysis indicated genes involved in ER and oxidative stress were also significantly enriched. In addition, upstream analysis showed AMPK was activated upon WFA treatment. We then validated AMPK activation was sufficient to suppress TGF‐beta‐mediated epithelial‐to‐mesenchymal transition through knockdown of AK4. Furthermore, in vivo therapeutic model showed that WFA administration significantly decreased lung orthotopic xenograft tumor growth and liver and kidney metastasis compared to the control group. These results identify WFA can be applied to treat metastatic lung cancer through repurposing approved drugs that reverse AK4‐associated gene expression signature.

Tumour-suppression function of KLF12 through regulation of anoikis.

Suppression of detachment-induced cell death, known as anoikis, is an essential step for cancer metastasis to occur. We report here that expression of KLF12, a member of the Kruppel-like family of transcription factors, is downregulated in lung cancer cell lines that have been selected to grow in the absence of cell adhesion. Knockdown of KLF12 in parental cells results in decreased apoptosis following cell detachment from matrix. KLF12 regulates anoikis by promoting the cell cycle transition through S phase and therefore cell proliferation. Reduced expression levels of KLF12 results in increased ability of lung cancer cells to form tumours in vivo and is associated with poorer survival in lung cancer patients. We therefore identify KLF12 as a novel metastasis-suppressor gene whose loss of function is associated with anoikis resistance through control of the cell cycle.

Micro ribonucleic acid (RNA)-101 inhibits cell proliferation and invasion of lung cancer by regulating cyclooxygenase-2.

BackgroundMicro ribonucleic acid (miR-101) can regulate the expression of cyclooxygenase-2 (COX-2) and participate in the pathogenesis of malignant tumors. This study investigates the effects of miRNA-101 and COX-2 in lung cancer and the impact of miR-101 on the proliferation and invasion of human lung cancer A549 cell line.MethodsThe expression of miR-101 in 20 separate lung cancer tissues was detected by real time polymerase chain reaction; COX-2 expression was also detected. A549 cells were transfected with miR-101 or negative control oligonucleotide duplex mimic (miR-NC). In vivo tumorigenesis abilities were detected in localized human lung cancer xeno-transplant models in BALB/c nude mice.ResultsMiR-101 expression was significantly lower and the level of COX-2 significantly higher in lung cancer tissues than in adjacent parenchyma (2.918 ± 1.006 vs. 5.953 ± 1.976, P = 0.001; 0.887 ± 0.260 vs. 0.355 ± 0.156, P = 0.001, respectively). Correlation analysis revealed that miR-101 negatively correlated with COX-2 in lung cancer tissues (R = −0.596, P = 0.002). Compared with A549-miR-NC cells, the expression of COX-2 was significantly decreased in A549 cells transfected with miR-101 (P < 0.001). The proliferation of A549 cells was markedly inhibited after transfection of miR-101. The in vivo tumor growth of A549 cells transfected with miR-101 was significantly slower than wide type A549 cells.ConclusionMiR-101 expression is decreased in lung cancer, inducing an increase in COX-2 level. Enforced expression of miR-101 can remarkably reduce the cell proliferation and invasion ability of lung cancer cells.

ING5 inhibits cancer aggressiveness via preventing EMT and is a potential prognostic biomarker for lung cancer.

The proteins of the Inhibitor of Growth (ING) candidate tumor suppressor family are involved in multiple cellular functions such as cell cycle regulation, apoptosis, and chromatin remodeling. ING5 is the new member of the family whose actual role in tumor suppression is not known. Here we show that ING5 overexpression in lung cancer A549 cells inhibited cell proliferation and invasiveness, while ING5 knockdown in lung cancer H1299 cells promoted cell aggressiveness. ING5 overexpression also abrogated tumor growth and invasive abilities of lung cancer cells in mouse xenograft models. Further study showed that ING5 overexpression inhibited EMT indicated by increase of E-cadherin and decrease of N-cadherin, Snail and slug at mRNA and protein levels, which was accompanied with morphological changes. cDNA microarray and subsequent qRT-PCR validation revealed that ING5 significantly downregulated expression of EMT (epithelial to mesenchymal transition)-inducing genes including CEACAM6, BMP2 and CDH11. Clinical study by tissue microarray showed that nuclear ING5 negatively correlated with clinical stages and lymph node metastasis of lung cancer. Furthermore, high level of nuclear ING5 was associated with a better prognosis. Taken together, these findings uncover an important role for ING5 as a potent tumor suppressor in lung cancer growth and metastasis.

Capn4 promotes non-small cell lung cancer progression via upregulation of matrix metalloproteinase 2.

The expression of calpain small subunit 1 (Capn4) is correlated with the invasion of several types of tumors. However, the roles of Capn4 in non-small cell lung cancer (NSCLC) remain unclear. In this study, we found that the expression of Capn4 in NSCLC tissues was much higher than that in nontumorous samples. High levels of Capn4 expression were associated with lymph node metastasis and large tumor size in NSCLC patients. The 5-year overall survival rate in the Capn4(high) group was significantly lower than that in the Capn4(low) group. In multivariate analysis, Capn4 was identified as an independent prognostic factor for overall survival. Moreover, in an in vitro analysis, downregulation of Capn4 expression by siRNA suppressed the invasive potential of lung cancer cells. Finally, we demonstrated that Capn4 enhanced the invasion ability of lung cancer cells by upregulating the expression of matrix metalloproteinase 2. Our findings indicated that Capn4 may represent a potential therapeutic target and a novel prognostic marker of NSCLC.

Suppression of proliferation, tumorigenicity and metastasis of lung cancer cells after their transduction by interferon-beta gene in baculovirus vector

BackgroundGene therapy represents an interesting alternative treatment for cancers. Interferon-beta is well known as a multifunctional cytokine that provides antiviral, antiproliferative, antiangiogenic and immunomodulating effects. For this reason introduction of this cytokine gene in baculovirus vector is seen as a rather promising tool for anticancer therapy. AimInvestigation of biological behavior in vitro and in vivo of lung cancer cells modified by interferon-beta gene which was introduced into the cells in vitro with baculovirus vector. Materials and MethodsStudies were performed on mouse Lewis lung carcinoma cells as the tumor model (LL cell line). Transductions of cells by recombinant baculoviruses, in vitro and in vivo analysis of tumor cell biology and immunocytochemical method have been used. ResultsThe study of various in vitro biological parameters of LL cancer cells transduced by recombinant baculovirus with interferon gene demonstrated that the transduction of cells is accompanied by significant inhibition of their proliferation and ability to form colonies in semisolid agar. Also, transduction of LL cells with interferon gene inhibited their tumorigenicity, i.e. the ability to cause formation of tumors and metastases in lungs of mice in vivo. Anti-tumor activity of recombinant interferon is realized via high level of its local production in tumors, induced by LL carcinoma cells, transduced with recombinant interferon-beta gene. Recombinant baculovirus without interferon gene did not influence significantly on tumorigenicity and metastatic ability of lung cancer cells. ConclusionsIntroduction of interferon-beta gene in Lewis lung carcinoma cells in vitro in recombinant baculovirus leads to inhibition of their proliferation potential and malignant behavior in vitro, tumorigenicity and metastatic activity in vivo.

Lung cancer cells induce senescence and apoptosis of pleural mesothelial cells via transforming growth factor-beta1.

Pleural dissemination is commonly associated with metastatic advanced lung cancer. The injury of pleural mesothelial cells (PMCs) by soluble factors, such as transforming growth factor-beta1 (TGF-β1), is a major driver of lung cancer pleural dissemination (LCPD). In this study, we examine the effects of TGF-β1 on PMC injury and the ability of TGF-β1 inhibition to alleviate this effect both in vitro and in vivo. PMCs were co-cultured with the high TGF-β1-expressing lung cancer cell line A549 and with various TGF-β1 signaling inhibitors. Expression of cleaved-caspase 3, cleaved-caspase 9, p21, and p16 were evaluated by Western blot and immunofluorescent confocal imaging. Apoptosis was measured by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltrazoliumbromide assay and AnnexinV-propidium iodide (PI) staining. PMC senescence was assessed by staining for senescence-associated β-galactosidase (SA-β-Gal). The ability of lung cancer cells (LCCs) to adhere to injured PMCs was investigated using an LCC-PMC adhesion assay. In our mouse model, PMC injury status was monitored by hematoxylin-eosin (H&E) and Masson's trichrome staining. LCCs expressing high levels of TGF-β1 induce apoptosis and senescence of PMCs in a co-culture system. Injured PMCs adhere to LCCs, which may further promote LCPD. Importantly, PMC monolayer injury could be reversed with TGF-β1 inhibitors. This was consistent with our in vivo data showing that the TGF-β1 inhibitor SB-431542 attenuated PMC barrier injury induced by A549 culture medium in our mouse model. Our study highlights the importance of TGF-β1 signaling in LCPD and establishes this signaling pathway as a potential therapeutic target in the disease.

Abstract 5265: S100P increases Twist expression and triggers FAK/AKT signaling in lung cancer

Abstract Lung cancer accounts for 12% of all new cases of cancers worldwide and is the leading cause of cancer-related death. S100P, a calcium binding protein, has been reported to involve in cancer metastasis. However, the role of S100P is poorly known in lung cancer. This study first reports that S100P enhances the migration and invasion ability of lung cancer cells through the Twist1 upregulation and FAK (focal adhesion kinase)/Src/AKT signaling pathway. Compared to low invasive CL1-0, the expression of S100P is greater in that of high invasive CL1-5 cells. Overexpression of S100P increases the migration and invasion in CL1-0 cells, whereas knockdown of S100P expression decreases the migration and invasion of CL1-5 cells. Enhancement of S100P expression triggers FAK activation, which in turn increases the activation of Src and AKT signaling. Blockade of FAK by specific inhibitor prevents S100P-mediated cell migration and invasion. In the other hand, S100P also increases Twist1, which is responsible for epithelial-mesenchymal transition in lung cancer. More important, elevated expression of S100P protein was also found in human lung cancer specimen. This study demonstrates that S100P may be a novel anticancer target gene for the prevention of non-small cell lung cancer metastasis. In other way, it also can be a biomarker for prognosis of lung cancer metastasis. Citation Format: Yung-Yu Liang, Po-Lin Kuo, Ya-Ling Hsu. S100P increases Twist expression and triggers FAK/AKT signaling in lung cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5265. doi:10.1158/1538-7445.AM2014-5265

Identification analysis of eukaryotic expression plasmid Rap2a and its effect on the migration of lung cancer cells

背景与目的小G蛋白家族成员Rap2a可调控内皮素和细胞粘附从而影响细胞运动及细胞与基质间相互作用，但其在肿瘤发生发展中的作用仍属未知。克隆人Ras家族小G蛋白Rap2a的cDNA，构建其真核表达质粒并在肺癌细胞表达，初步探讨Rap2a在肺癌发生发展中的作用。方法Western blot检测Rap2a在肺癌细胞中的内源性表达。人骨肉瘤细胞株U2OS提取细胞总RNA，经逆转录聚合酶链式反应逆转录成cDNA，PCR扩增Rap2a基因，酶切后插入pcDNA3.1(+)构建真核表达质粒pcDNA3.1(+)-Rap2a，采用酶切及测序鉴定。重组质粒转染H1299和A549细胞，Western blot检测目的基因表达。Transwell小室迁移实验观察Rap2a对肺癌细胞迁移能力的影响。明胶酶谱实验检测Rap2a对细胞分泌基质金属蛋白酶（matrix metalloproteinase, MMP）2的影响。结果与正常细胞相比，肺癌细胞中Rap2a基础表达水平明显增高。双酶切及测序结果显示重组质粒pcDNA3.1(+)-Rap2a成功构建，Werstern blot检测到H1299和A549细胞有相应蛋白表达。迁移实验结果显示转染Rap2a基因后肿瘤细胞迁移能力明显增加。明胶酶谱实验结果显示Rap2a过表达后肺癌细胞分泌MMP2的量随之增加。结论人Rap2a真核表达质粒成功构建，Rap2a基因在肺癌细胞株成功表达并能促进肺癌细胞的迁移能力。

MicroRNA-133a suppresses multiple oncogenic membrane receptors and cell invasion in non-small cell lung carcinoma.

Non-small cell lung cancers (NSCLCs) cause high mortality worldwide, and the cancer progression can be activated by several genetic events causing receptor dysregulation, including mutation or amplification. MicroRNAs are a group of small non-coding RNA molecules that function in gene silencing and have emerged as the fine-tuning regulators during cancer progression. MiR-133a is known as a key regulator in skeletal and cardiac myogenesis, and it acts as a tumor suppressor in various cancers. This study demonstrates that miR-133a expression negatively correlates with cell invasiveness in both transformed normal bronchial epithelial cells and lung cancer cell lines. The oncogenic receptors in lung cancer cells, including insulin-like growth factor 1 receptor (IGF-1R), TGF-beta receptor type-1 (TGFBR1), and epidermal growth factor receptor (EGFR), are direct targets of miR-133a. MiR-133a can inhibit cell invasiveness and cell growth through suppressing the expressions of IGF-1R, TGFBR1 and EGFR, which then influences the downstream signaling in lung cancer cell lines. The cell invasive ability is suppressed in IGF-1R- and TGFBR1-repressed cells and this phenomenon is mediated through AKT signaling in highly invasive cell lines. In addition, by using the in vivo animal model, we find that ectopically-expressing miR-133a dramatically suppresses the metastatic ability of lung cancer cells. Accordingly, patients with NSCLCs who have higher expression levels of miR-133a have longer survival rates compared with those who have lower miR-133a expression levels. In summary, we identified the tumor suppressor role of miR-133a in lung cancer outcome prognosis, and we demonstrated that it targets several membrane receptors, which generally produce an activating signaling network during the progression of lung cancer.

The effect of catalase on migration and invasion of lung cancer cells by regulating the activities of cathepsin S, L, and K

Abundant clinical evidences indicate that up-regulation of several cathepsins in many human cancers is correlated with malignant progression and poor patient prognosis. In addition, a decrease in catalase activity or accumulation of hydrogen peroxide correlates with cancer metastasis. Recent studies indicate that cathepsin activation and expression can be modulated via H2O2 treatment. However, the actual relationship between catalase and cathepsins is not yet fully understood. In the present study, we found that catalase expression (or activity) was higher, while intracellular and extracellular Cat S, Cat L, and Cat K activities were lower in the non-invasive CL1-0 cells compared to the highly invasive CL1-5 cells. After CL1-0 cells were transfected with catalase-shRNA, the corresponding ROS (H2O2) level and Cat S, Cat L, or Cat K expression (or activity) was up-regulated, accompanied by an increase in cell migration and invasion. On the other hand, ROS (H2O2) level, cathepsin S, L, and K activities, cell migration and invasion were decreased in catalase-overexpressed CL1-5 cells. It is suggested that catalase may regulate cathepsin activity by controlling the production of ROS (H2O2), leading to variation in migration and invasion ability of lung cancer cells.

RASSF3 downregulation increases malignant phenotypes of non-small cell lung cancer

BackgroundRas-Association Family1A (RASSF1A) is a well-established tumor suppressor. Ten RASSF homologues comprise this family, and each member is considered a tumor suppressor. RASSF3 is one of the RASSF family members, but its function has not yet been clarified. Recently, we found that RASSF3 interacts with MDM2 and facilitates its ubiquitination, which induces apoptosis through p53 stabilization. However, the role of RASSF3 in human malignancies remains largely unknown. Patients and methodsNinety-five non-small cell lung cancer (NSCLC) patients from Nagoya University Hospital and 45 NSCLC patients from Aichi Cancer Center Hospital underwent pulmonary resection at each hospital, and lung cancer and corresponding non-cancerous lung tissues were collected. The expression levels of RASSF3 were analyzed using quantitative real-time reverse transcription PCR. We performed statistical analysis to investigate the correlation with RASSF3 expression and the clinicopathological characteristics. We also transfected RASSF3-siRNA into NSCLC cells, and performed motility assays to evaluate the influence on migration ability. ResultsRASSF3 expression levels were downregulated in 125 of a total 140 NSCLCs. In a multivariate logistic regression analysis, the low RASSF3 expression group below the median value was independently correlated with progressive phenotypes (lymph node metastasis and pleural invasion), non-adenocarcinoma histology and wild-type epidermal growth factor receptor (EGFR) status. In motility assays, RASSF3-knockdown NSCLC cells increased the migration rate compared to the control cells. ConclusionsWe found that the expression levels of RASSF3 were frequently downregulated in NSCLCs. Downregulation of RASSF3 strongly correlated with the progressive phenotypes of NSCLCs and EGFR wild-type status. In vitro studies also suggested that RASSF3 downregulation increases migration ability of lung cancer cells. Together, our findings indicate RASSF3 is a candidate tumor suppressor gene of NSCLCs.

Luteolin attenuates TGF-β1-induced epithelial–mesenchymal transition of lung cancer cells by interfering in the PI3K/Akt–NF-κB–Snail pathway

AimsLuteolin is a natural flavonoid that possesses a variety of pharmacological activities, such as anti-inflammatory and anti-cancer abilities. Whether luteolin regulates the transformation ability of lung cancer cells remains unclear. The current study aims to uncover the effects and underlying mechanisms of luteolin in regulation of and epithelial–mesenchymal transition of lung cancer cells. Main methodsThe lung adenocarcinoma A549 cells were used in this experiment; the cells were pretreated with luteolin followed by administration with TGF-β1. The expression levels of various cadherin and related upstream regulatory modules were examined. Key findingsPretreatment of luteolin prevented the morphological change and downregulation of E-cadherin of A549 cells induced by TGF-β1. In addition, the activation of PI3K–Akt–IκBa–NF-κB–Snail pathway which leads to the decline of E-cadherin induced by TGF-β1 was also attenuated under the pretreatment of luteolin. SignificanceWe provide the mechanisms about how luteolin attenuated the epithelial–mesenchymal transition of A549 lung cancer cells induced by TGF-β1. This finding will strengthen the anti-cancer effects of flavonoid compounds via the regulation of migration/invasion and EMT ability of various cancer cells.

Aberrant hypermethylation and reduced expression of disabled-2 promote the development of lung cancers

Disabled-2 (Dab2) is considered a tumor suppressor and is downregulated in cancers. We examined the promoter methylation status and expression levels of Dab2, and investigated their roles in the development of lung cancers. Methylation-specific PCR was employed to analyze the methylation status of Dab2 in 100 lung cancer tissues. The cytoplasmic and nuclear expression of the Dab2 protein was determined using western blot analysis. Demethylation treatment using 5-Aza-2-deoxycytidine (5-Aza-dC) was performed in three lung cancer cell lines. Dab2 expression was upregulated by Dab2 transfection or interrupted by Dab2 siRNA in lung cancer cells. Proliferative and invasive ability tests were performed with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTS) and a Matrigel invasion assay, respectively. The methylation rate of Dab2 was significantly higher in lung cancer tissues compared to normal lung tissues. Dab2 methylation correlated with the reduced nuclear and cytoplasmic expression of Dab2, as well as the TNM stage and lymphatic metastasis of lung cancers. Treatment with 5-Aza-dC was able to eliminate the hypermethylation of Dab2, enhance Dab2 expression, and inhibit β-catenin expression, and the proliferative and invasive ability of lung cancer cells. Upregulation of Dab2 expression reduced β-catenin expression and proliferation and invasiveness of lung cancer cells. However, interruption of Dab2 expression induced the opposite results. Dab2 methylation is common in lung cancers, and is one of the most important factors responsible for the reduced expression of Dab2. Aberrant hypermethylation and reduced expression of Dab2 promote the development of lung cancers.

High expression of SNIP1 correlates with poor prognosis in Non-small cell lung cancer and SNIP1 interferes with the recruitment of HDAC1 to RB in vitro

The Rb tumor suppressor gene performs a critical role in controlling cell proliferation and tumorigenesis; it recruits HDAC1 protein into the E2F complexes to repress transcription. In this study, we demonstrate that SNIP1, RB and HDAC1 were significantly expressed in same lung cancer tissues in a tissue microarray (TMA) containing 300 non-small cell lung cancers (NSCLC). High expression level of SNIP1 in tumor patients was significantly correlated with poor prognosis in NSCLC (log-rank P for OS=0.01, log-rank P for DFS=0.001). Functionally, SNIP1 competes with HDAC1 for binding to RB and reduces HDAC activity in vitro. Knockdown of SNIP1 reduced colony formation ability of lung cancer cells. These findings may indicate the involvement of SNIP1 in progression of lung cancer by regulating the RB/HDAC1 interaction.

Ataxia–telangiectasia group D complementing gene (ATDC) upregulates matrix metalloproteinase 9 (MMP-9) to promote lung cancer cell invasion by activating ERK and JNK pathways

Although the expression pattern and biological functions of ataxia-telangiectasia group D complementing gene (ATDC) had been implicated in several types of cancer, the roles and potential mechanisms of ATDC in lung cancer cell invasion are still ambiguous. In this study, we used gain- and loss-of-function analyses to explore the roles and potential mechanisms of ATDC in lung cancer cell invasion. siRNA knockdown of ATDC impaired cell invasion in A549 and H1299 cell lines, and its overexpression promoted cell invasion in HBE cell line. ATDC may contribute to the invasive ability of lung cancer cells by promoting the expression of invasion-related matrix metalloproteinase 9 (MMP-9). In addition, ATDC increased activating protein 1 (AP-1) reporter luciferase activity and the protein and mRNA levels of c-Jun and c-Fos. We further demonstrated that the roles of ATDC on cell invasion, MMP-9 upregulation, and AP-1 activation were dependent on extracellular signal-regulated protein kinase (ERK) and c-Jun N-terminal kinase (JNK) pathway activation, and ERK inhibitor U0126 or JNK inhibitor SP600125 blocked these effects of ATDC. These results suggested that ATDC upregulates MMP-9 to promote lung cancer cell invasion by activating ERK and JNK pathways.