Altered expression of adhesion molecules and epithelial-mesenchymal transition in silica-induced rat lung carcinogenesis

Glutamine induces remodeling of tight junctions in Caco-2 colorectal cancer cell

Malignant cells often exhibit significant metabolic alterations, including the utilization of different nutrients to meet energetic and biosynthetic demands. Recent studies have shown that glutamine can support primary colorectal tumor growth and also serve as an alternate energy source during distant metastasis under glucose-limited conditions. However, the overall effects of glutamine on cancer cell physiology are not completely understood. In this study, we investigated how glutamine impacts epithelial integrity in colorectal cancer cells under glucose deprivation. Human colorectal cancer (Caco-2) cells were grown to confluency in transwells and cultured in glucose/pyruvate-free DMEM with various glutamine concentrations (0-50 mM). Cell viability was assessed, and monolayer integrity was examined in terms of transepithelial resistance (TER) and paracellular permeability. Tight junction (TJ) component proteins were examined by immunofluorescence staining and Western blotting. A dose-dependent decrease in TER was observed in Caco-2 cells, but paracellular permeability was not affected after 24 h incubation with glutamine. At the same time, the TJ proteins, zonula occludens (ZO)-1 and Claudin-1, showed lateral undulations and punctate staining patterns accompanied by enlargement of cellular and nuclear sizes. Furthermore, decreased protein levels of ZO-1, but not claudin-1, were found in detergent-insoluble cellular fractions. Notably, the decreased TER and alterations in TJ structure were not associated with cell viability changes. Moreover, the addition of glutamate, which is produced by the first step of glutamine catabolism, had no impact on TER. Our results suggested that the enteral glutamine may play an important role in the regulation of TJ dynamics in colorectal cancer cells.

Downregulation of CD166 inhibits invasion, migration, and EMT in the radio-resistant human nasopharyngeal carcinoma cell line CNE-2R

Objective: CD166 is known as a tumor stem cell specific marker, associating with tumor metastasis. The purpose of this study was to further discuss CD166 gene on cell proliferation, invasion, metastasis, and the epithelial-mesenchymal transition (EMT) in CNE-2R cell line of nasopharyngeal carcinoma (NPC). Materials and methods: CNE-2R cells were transfected with lentivirus CD166-shRNA, and quantitative reverse transcription polymerase chain reaction (RT-qPCR), and Western blotting were used to confirm the silencing effects. The wound healing test and transwell test were carried out to assess cell invasive and migratory abilities in vitro. With the establishment of xenograft nude mouse model, Western blotting and immunohistochemistry were undertaken to detect the expression level of E-cadherin, N-cadherin, and vimentin. In vivo metastasis detection was carried out by injecting tumor cells into nude mice via the tail vein. Results: The invasive and migratory abilities of CNE-2R cells were significantly reduced after CD166 was downregulated. In addition, silencing of CD166 of CNE-2R cells increased the expression of E-cadherin, while down-regulated the expression of N-cadherin and vimentin. Immunohistochemistry of tumors showed consistent results with in-situ tumor formation experiment. Additionally, the growth of transplanted tumor was inhibited. In addition, in vivo metastasis test proved that knockdown of CD166 suppressed pulmonary metastasis and liver metastasis according to hematoxylin and eosin (H&E) staining. Expression of E-cadherin increased, while expression of N-cadherin and vimentin decreased, as revealed by Western blotting of metastatic lung tumors. Conclusion: Silencing of CD166 in CNE-2R cells evidently inhibited proliferation, invasion, metastasis, and EMT process in vivo and in vitro.

The emerging roles of a novel CCCH-type zinc finger protein, ZC3H4, in silica-induced epithelial to mesenchymal transition

BACKGROUND

The epithelial to mesenchymal transition (EMT) contributes to fibrosis during silicosis. Zinc finger CCCH-type containing 4 protein (ZC3H4) is a novel CCCH-type zinc finger protein that activates inflammation in pulmonary macrophages during silicosis. However, whether ZC3H4 is involved in EMT during silicosis remains unclear. In this study, we investigated the circular ZC3H4 (circZC3H4) RNA/microRNA-212 (miR-212) axis as the upstream molecular mechanism regulating ZC3H4 expression and the downstream mechanism by which ZC3H4 regulates EMT as well as its accompanying migratory characteristics.

METHODS

The protein levels were assessed via Western blotting and immunofluorescence staining. Scratch assays were used to analyze the increased mobility induced by silica. The CRISPR/Cas9 system and small interfering RNAs (siRNAs) were employed to analyze the regulatory mechanisms of ZC3H4 in EMT and migration changes.

RESULTS

Specific knockdown of ZC3H4 blocked EMT and migration induced by silicon dioxide (SiO₂). Endoplasmic reticulum (ER) stress mediated the effects of ZC3H4 on EMT. circZC3H4 RNA served as an miR-212 sponge to regulate ZC3H4 expression, which played a pivotal role in EMT. Tissue samples from mice and patients confirmed the upregulation of ZC3H4 in alveolar epithelial cells.

CONCLUSIONS

ZC3H4 may act as a novel regulator in the progression of SiO₂-induced EMT, which provides a reference for further pulmonary fibrosis research.

Polo-like kinase 4 mediates epithelial-mesenchymal transition in neuroblastoma via PI3K/Akt signaling pathway

Neuroblastoma (NB) is the most common malignant tumor in infancy and most common extracranial solid tumor in childhood. With the improvement of diagnosis and treatment, the survival rate of patients with low-risk and intermediate-risk NB can reach up to 90%. In contrast, for high-risk NBs, the long-term survival rate is still <40% because of heterogeneity of this tumor. The pathogenesis of NB is still not explicit, therefore it is of great significance to explore the mechanism of NB tumorigenesis and discover new therapeutic targets for NB. Polo-like kinase 4 (PLK4), one of the polo-like kinase family members, is an important regulator of centriole replication. The aberrant expression of PLK4 was found in several cancers and a recent study has unraveled a novel function of PLK4 as a mediator of invasion and metastasis in Hela and U2OS cells. However, the function of PLK4 in NB development and progression remains to be elucidated. The study showed the expression level of PLK4 in NB tissues was remarkably upregulated and high expression of PLK4 was negatively correlated with clinical features and survival, which suggested that PLK4 could be a potential tumor-promoting factor of NB. Functional studies indicated downregulation of PLK4 suppressed migration and invasion and promoted apoptosis in NB cells. Further experiments showed that downregulation of PLK4 in NB cells inhibited EMT through the PI3K/Akt signaling pathway. Animal experiments demonstrated that the downregulation of PLK4 in SK-N-BE(2) cells dramatically suppressed tumorigenesis and metastasis. PLK4 may be a promising therapeutic target for NB.

Characterization of preneoplastic and neoplastic rat mesothelial cell lines: the involvement of TETs, DNMTs, and 5-hydroxymethylcytosine

Malignant mesothelioma (MM) is one of the worst cancers in terms of clinical outcome, urging the need to establish and characterize new preclinical tools for investigation of the tumorigenic process, improvement of early diagnosis and evaluation of new therapeutic strategies. For these purposes, we characterized a collection of 27 cell lines established from F344 rats, after 136 to 415 days of induction with crocidolite asbestos administered intraperitoneally. Four mesotheliomas were distinguished from 23 preneoplastic mesothelial cell lines (PN) according to their propensity to generate tumors after orthotopic transplantation into syngeneic rats, their growth pattern, and the expression profile of three genes. PN cell lines were further discriminated into groups / subgroups according to morphology in culture and the expression profiles of 14 additional genes. This approach was completed by analysis of positive and negative immunohistochemical MM markers in the four tumors, of karyotype alterations in the most aggressive MM cell line in comparison with a PN epithelioid cell line, and of human normal mesothelial and mesothelioma cells and a tissue array. Our results showed that both the rat and human MM cell lines shared in common a dramatic decrease in the relative expression of Cdkn2a and of epigenetic regulators, in comparison with PN and normal human mesothelial cells, respectively. In particular, we identified the involvement of the relative expression of the Ten-Eleven Translocation (TET) family of dioxygenases and Dnmt3a in relation to the 5-hydroxymethylcytosine level in malignant transformation and the acquisition of metastatic potential.

Hypoxia modulates the stem cell population and induces EMT in the MCF-10A breast epithelial cell line

A common feature among pre-malignant lesions is the induction of hypoxia through increased cell propagation and reduced access to blood flow. Hypoxia in breast cancer has been associated with poor patient prognosis, resistance to chemotherapy and increased metastasis. Although hypoxia has been correlated with factors associated with the latter stages of cancer progression, it is not well documented how hypoxia influences cells in the earliest stages of transformation. Using the immortalized MCF-10A breast epithelial cell line, we used hypoxic culture conditions to mimic reduced O2 levels found within early pre-malignant lesions and assessed various cellular parameters. In this non-transformed mammary cell line, O2 deprivation led to some changes not immediately associated with cancer progression, such as decreased proliferation, cell cycle arrest and increased apoptosis. In contrast, hypoxia did induce other changes more consistent with an increased metastatic potential. A rise in the CD44+CD24-/low-labeled cell sub-population along with increased colony forming capability indicated an expanded stem cell population. Hypoxia also induced cellular and molecular changes consistent with an epithelial-to-mesenchymal transition (EMT). Furthermore, these cells now exhibited increased migratory and invasive abilities. These results underscore the contribution of the hypoxic tumour microenvironment in cancer progression and dissemination.

WNT signaling - lung cancer is no exception

Since the initial discovery of the oncogenic activity of WNT ligands our understanding of the complex roles for WNT signaling pathways in lung cancers has increased substantially. In the current review, the various effects of activation and inhibition of the WNT signaling pathways are summarized in the context of lung carcinogenesis. Recent evidence regarding WNT ligand transport mechanisms, the role of WNT signaling in lung cancer angiogenesis and drug transporter regulation and the importance of microRNA and posttranscriptional regulation of WNT signaling are also reviewed.

Down-regulation of E-cadherin enhances prostate cancer chemoresistance via Notch signaling

Background

The chemoresistance of prostate cancer (PCa) is invariably associated with the aggressiveness and metastasis of this disease. New emerging evidence indicates that the epithelial-to-mesenchymal transition (EMT) may play pivotal roles in the development of chemoresistance and metastasis. As a hallmark of EMT, E-cadherin is suggested to be a key marker in the development of chemoresistance. However, the molecular mechanisms underlying PCa chemoresistance remain unclear. The current study aimed to explore the association between EMT and chemoresistance in PCa as well as whether changing the expression of E-cadherin would affect PCa chemoresistance.

Methods

Parental PC3 and DU145 cells and their chemoresistant PC3-TxR and DU145-TxR cells were analyzed. PC3-TxR and DU145-TxR cells were transfected with E-cadherin-expressing lentivirus to overexpress E-cadherin; PC3 and DU145 cells were transfected with small interfering RNA to silence E-cadherin. Changes of EMT phenotype-related markers and signaling pathways were assessed by Western blotting and quantitative real-time polymerase chain reaction. Tumor cell migration, invasion, and colony formation were then evaluated by wound healing, transwell, and colony formation assays, respectively. The drug sensitivity was evaluated using MTS assay.

Results

Chemoresistant PC3-TxR and DU145-TxR cells exhibited an invasive and metastatic phenotype that associated with EMT, including the down-regulation of E-cadherin and up-regulation of Vimentin, Snail, and N-cadherin, comparing with that of parental PC3 and DU145 cells. When E-cadherin was overexpressed in PC3-TxR and DU145-TxR cells, the expression of Vimentin and Claudin-1 was down-regulated, and tumor cell migration and invasion were inhibited. In particular, the sensitivity to paclitaxel was reactivated in E-cadherin-overexpressing PC3-TxR and DU145-TxR cells. When E-cadherin expression was silenced in parental PC3 and DU145 cells, the expression of Vimentin and Snail was up-regulated, and, particularly, the sensitivity to paclitaxel was decreased. Interestingly, Notch-1 expression was up-regulated in PC3-TxR and DU145-TxR cells, whereas the E-cadherin expression was down-regulated in these cells comparing with their parental cells. The use of γ-secretase inhibitor, a Notch signaling pathway inhibitor, significantly increased the sensitivity of chemoresistant cells to paclitaxel.

Conclusion

The down-regulation of E-cadherin enhances PCa chemoresistance via Notch signaling, and inhibiting the Notch signaling pathway may reverse PCa chemoresistance.

Global DNA methylation and PTEN hypermethylation alterations in lung tissues from human silicosis

BACKGROUND

Silicosis is a respiratory disease caused by long-term silica dust exposure. Our previous study has demonstrated that silica mediates the activation of phosphatidylinositol 3-kinase (PI3K)/phosphatase and tensin homolog deleted on chromosome 10 (PTEN)/serine or threonine kinase (AKT)/mitogen-activated protein kinases (MAPK)/AP-1 pathway in human embryo lung fibroblasts (HELFs). The purpose of this study is to identify genome-wide aberrant DNA methylation profiling in lung tissues from silicosis patients.

METHODS

We performed Illumina Human Methylation 450K Beadchip arrays to investigate the methylation alteration in formalin-fixed, paraffin-embedded (FFPE) lung specimens, immunohistochemistry to detect the level of c-Jun and PTEN proteins; methylation specific PCR (MS-PCR) to identify PTEN and c-Jun promoter methylation in HELFs.

RESULTS

We found 86,770 CpG sites and 79,660 CpG sites significantly differed in methylation status in early-stage and advanced-stage compared with GEO normal lung methylation data. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed the methylated status of MAPK signaling pathway was considered changed. The number of PTEN and c-Jun CpG promoter methylated-sites were increased in advanced-stage. Early-stage showed the positive expression of c-Jun and PTEN protein and negative or mild expression in advanced-stage. PTEN promoter was no differentially methylated and c-Jun promoter differed at 12 and 24 h in HELFs.

CONCLUSIONS

Abnormal DNA methylation on genome-scale was implicated in silicosis, and PTEN promoter hypermethylation might be associated with decrease of PTEN protein.

Matrix-Gla protein promotes osteosarcoma lung metastasis and associates with poor prognosis

Osteosarcoma (OS) is the most prevalent osseous tumour in children and adolescents and, within this, lung metastases remain one of the factors associated with a dismal prognosis. At present, the genetic determinants driving pulmonary metastasis are poorly understood. We adopted a novel strategy using robust filtering analysis of transcriptomic profiling in tumour osteoblastic cell populations derived from human chemo-naive primary tumours displaying extreme phenotypes (indolent versus metastatic) to uncover predictors associated with metastasis and poor survival. We identified MGP, encoding matrix-Gla protein (MGP), a non-collagenous matrix protein previously associated with the inhibition of arterial calcification. Using different orthotopic models, we found that ectopic expression of Mgp in murine and human OS cells led to a marked increase in lung metastasis. This effect was independent of the carboxylation of glutamic acid residues required for its physiological role. Abrogation of Mgp prevented lung metastatic activity, an effect that was rescued by forced expression. Mgp levels dramatically altered endothelial adhesion, trans-endothelial migration in vitro and tumour cell extravasation ability in vivo. Furthermore, Mgp modulated metalloproteinase activities and TGFβ-induced Smad2/3 phosphorylation. In the clinical setting, OS patients who developed lung metastases had high serum levels of MGP at diagnosis. Thus, MGP represents a novel adverse prognostic factor and a potential therapeutic target in OS. Microarray datasets may be found at: http://bioinfow.dep.usal.es/osteosarcoma/ Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Identification of methylation markers for the prediction of nodal metastasis in oral and oropharyngeal squamous cell carcinoma

Hypermethylation is an important mechanism for the dynamic regulation of gene expression, necessary for metastasizing tumour cells. Our aim is to identify methylation tumour markers that have a predictive value for the presence of regional lymph node metastases in patients with oral and oropharyngeal squamous cell carcinoma (OOSCC). Significantly differentially expressed genes were retrieved from four reported microarray expression profiles comparing pN0 and pN+ head-neck tumours, and one expression array identifying functionally hypermethylated genes. Additional metastasis-associated genes were included from the literature. Thus genes were selected that influence the development of nodal metastases and might be regulated by methylation. Methylation-specific PCR (MSP) primers were designed and tested on 8 head-neck squamous cell carcinoma cell lines and technically validated on 10 formalin-fixed paraffin-embedded (FFPE) OOSCC cases. Predictive value was assessed in a clinical series of 70 FFPE OOSCC with pathologically determined nodal status. Five out of 28 methylation markers (OCLN, CDKN2A, MGMT, MLH1 and DAPK1) were frequently differentially methylated in OOSCC. Of these, MGMT methylation was associated with pN0 status (P = 0.02) and with lower immunoexpression (P = 0.02). DAPK1 methylation was associated with pN+ status (P = 0.008) but did not associate with protein expression. In conclusion, out of 28 candidate genes, two (7%) showed a predictive value for the pN status. Both genes, DAPK1 and MGMT, have predictive value for nodal metastasis in a clinical group of OOSCC. Therefore DNA methylation markers are capable of contributing to diagnosis and treatment selection in OOSCC. To efficiently identify additional new methylation markers, genome-wide methods are needed.

Glyoxalase I drives epithelial-to-mesenchymal transition via argpyrimidine-modified Hsp70, miR-21 and SMAD signalling in human bronchial cells BEAS-2B chronically exposed to crystalline silica Min-U-Sil 5: Transformation into a neoplastic-like phenotype

Glyoxalase I (Glo1) is the main scavenging enzyme of methylglyoxal (MG), a potent precursor of advanced glycation end products (AGEs). AGEs are known to control multiple biological processes, including epithelial to mesenchymal transition (EMT), a multistep phenomenon associated with cell transformation, playing a major role in a variety of diseases, including cancer. Crystalline silica is a well-known occupational health hazard, responsible for a great number of human pulmonary diseases, such as silicosis. There is still much debate concerning the carcinogenic role of crystalline silica, mainly due to the lack of a causal demonstration between silica exposure and carcinogenesis. It has been suggested that EMT might play a role in crystalline silica-induced lung neoplastic transformation. The aim of this study was to investigate whether, and by means of which mechanism, the antiglycation defence Glo1 is involved in Min-U-Sil 5 (MS5) crystalline silica-induced EMT in BEAS-2B human bronchial epithelial cells chronically exposed, and whether this is associated with the beginning of a neoplastic-like transformation process. By using gene silencing/overexpression and scavenging/inhibitory agents, we demonstrated that MS5 induced hydrogen peroxide-mediated c-Jun-dependent Glo1 up-regulation which resulted in a decrease in the Argpyrimidine-modified Hsp70 protein level which triggered EMT in a novel mechanism involving miR-21 and SMAD signalling. The observed EMT was associated with a neoplastic-like phenotype. The results obtained provide a causal in vitro demonstration of the MS5 pro-carcinogenic transforming role and more importantly they provide new insights into the mechanisms involved in this process, thus opening new paths in research concerning the in vivo study of the carcinogenic potential of crystalline silica.

Immunohistochemical localization of epidermal growth factor system in the lung of the Japanese quail (Coturnix coturnix japonica) during the post-hatching period

The purpose of this study is to determine the possible changes in the localization of the four Epidermal Growth Factor Receptors and three ligands in quail lungs from the first day of hatching until the 125th after hatching using immunohistochemical methods. Immunohistochemical results demonstrated that four EGFRs and their ligands are chiefly located in the cytoplasm of cells. Additionally, ErbB4, AREG, and NRG1 are localized to the nucleus and nucleolus, but EGF is present in the nucleolus. ErbB2 was also found in the cell membrane. In the epithelium of secondary bronchi, the goblet cells only exhibited ErbB1 and ErbB2, whereas the basal and ciliated cells exhibited EGFRs and ligands immunoreactivity. The atrial granular cells displayed moderate levels of ErbB1-ErbB3 and EGF and strong levels of ErbB4, AREG, and NRG1 immunoreactivity. While the squamous atrial cells and squamous respiratory cells of air capillaries and endothelial cells of blood capillaries exhibited moderate to strong ErbB2, ErbB4, AREG, and NRG1 immunoreactivity, they had negative or weak ErbB1, ErbB3, and EGF immunoreactivity. The expression levels of ErbB2-ErbB4, EGF, AREG, and NRG1 were also detected in fibroblasts. Although ErbB2 was highly expressed in the bronchial and vascular smooth muscle cells, weak expression of ErbB1, ErbB3, AREG and EGF and moderate expression of ErbB4 and NRG1 were observed. Macrophages were only negative for ErbB1. In conclusion, these data indicate that the EGFR-system is functionally active at hatching, which supports the hypothesis that the members of EGFR-system play several cell-specific roles in quail lung growth after hatching.

Down regulated expression of Claudin-1 and Claudin-5 and up regulation of β-catenin: association with human glioma progression

Glioblastoma multiforme is the most common form of intracranial malignancy in humans, and is characterized by aggressive tumor growth, tissue invasion and neurodegenerative properties. The present study investigated the expression status of tight junction associated Claudin 1 (CLDN1), Claudin 5 (CLDN5) and Adheren junction associated β-catenin genes in the light of their critical role in the progression of both low- and high-grade human gliomas. Using quantitative PCR and Western blot methods the mRNA and protein status of CLDN1, CLDN5 and β-catenin genes were studied in a total of 25 human gliomas of World Health Organization (WHO) grades I-IV, non-cancerous control brain tissues and their corresponding model cell lines (C6, U373, U118, T98 and U87MG). Quantitative analysis of the transcript and protein expression data showed that CLDN1 and CLDN5 were significantly down regulated (p=<0.001) in tumors of all four grades and model cell lines. This decrease in expression pattern was in accordance with the increasing grade of the tumor. A 4-fold stronger reduction of CLDN1 when compared to CLDN5 was evident in high-grade tumors. Interestingly, β-catenin was up regulated in all tumor types we studied (p=<0.005). Our findings, suggest that down regulated CLDN1 and CLDN5 genes have potential relevance in relation to the progression of glioblastoma multiforme. Hence, their therapeutic targeting may provide both insight and leads to control the cellular proliferation and subsequent invasiveness among affected individuals.

miR-210 regulates the interaction between pancreatic cancer cells and stellate cells

There is accumulating evidence that pancreatic stellate cells (PSCs) promote the progression of pancreatic cancer. microRNAs (miRNAs) are small non-coding RNAs acting as negative regulators of gene expression at the post-transcriptional level. This study aimed to clarify the role of miRNAs in the interaction between PSCs and pancreatic cancer cells. Pancreatic cancer cells were mono-cultured or indirectly co-cultured with PSCs. miRNAs were prepared, and Agilent's miRNA microarray containing probes for 904 human miRNAs was used to identify differentially expressed miRNAs. miR-210 was identified as an upregulated miRNA by co-culture with PSCs. Conditioned media of PSCs activated ERK and Akt, but not hypoxia-inducible factor-1α pathway. PSCs-induced miR-210 upregulation was inhibited by inhibitors of ERK and PI3K/Akt pathways. Inhibition of miR-210 expression decreased migration, decreased the expression of vimentin and snai-1, and increased the membrane-associated expression of β-catenin in Panc-1 cells co-cultured with PSCs. In conclusion, our results suggest a novel role of miR-210 in the interaction between PSCs and pancreatic cancer cells.

TGF-β1 induces the dissolution of tight junctions in human renal proximal tubular cells: role of the RhoA/ROCK signaling pathway

The RhoA/ROCK signaling pathway plays a significant role in transforming growth factor (TGF)-β1-mediated epithelial-mesenchymal transition (EMT). It remains unclear, however, whether the RhoA/ROCK signaling pathway mediates TGF-β1-induced EMT by promoting the dissolution of tight junctions (TJs) in renal proximal tubular epithelial cells. In this study, we aimed to investigate the association between TGF-β1-mediated Rho/ROCK signaling and TJs in a cell line derived from human renal proximal tubular cells (HK-2 cells). HK-2 cells were treated with 5 ng/ml TGF-β1 for 0, 12, 24 and 48 h. Zona occludens protein 1 (also known as tight junction protein 1; ZO-1) and occludin mRNA and protein levels were determined by real-time PCR and western blot analysis, respectively. The HK-2 cells were then divided into three groups: a control group (serum-free culture medium for 24 h); a TGF-β1 group (treated with 5 ng/ml TGF-β1 for 24 h); and a TGF-β1 + Y-27632 (a specific ROCK inhibitor) group (pre-treated with 10 µM Y-27632 for 2 h and subsequently treated with 5 ng/ml TGF-β1 for 24 h). The levels of ZO-1 and occludin were detected by real-time PCR, western blot analysis and immunofluorescence. As shown by our results, the mRNA and protein levels of ZO-1 and occludin were decreased in the HK-2 cells following treatment with TGF-β1 in a time-dependent manner; in addition, ZO-1 and occludin levels in the TGF-β1 + Y-27632 group were significantly increased compared with those of the TGF-β1 group (P<0.05), with no significant changes compared with the control group. Our results indicate that the Rho/ROCK signaling pathway mediated by TGF-β1 plays a role in the dissolution of TJs during EMT.

Down-regulation of canonical and up-regulation of non-canonical Wnt signalling in the carcinogenic process of squamous cell lung carcinoma

The majority of lung cancers (LC) belong to the non-small cell lung carcinoma (NSCLC) type. The two main NSCLC sub-types, namely adenocarcinoma (AC) and squamous cell carcinoma (SCC), respond differently to therapy. Whereas the link between cigarette smoke and lung cancer risk is well established, the relevance of non-canonical Wnt pathway up-regulation detected in SCC remains poorly understood. The present study was undertaken to investigate further the molecular events in canonical and non-canonical Wnt signalling during SCC development. A total of 20 SCC and AC samples with matched non-cancerous controls were obtained after surgery. TaqMan array analysis confirmed up-regulation of non-canonical Wnt5a and Wnt11 and identified down-regulation of canonical Wnt signalling in SCC samples. The molecular changes were tested in primary small airway epithelial cells (SAEC) and various lung cancer cell lines (e.g. A549, H157, etc). Our studies identified Wnt11 and Wnt5a as regulators of cadherin expression and potentiated relocation of β-catenin to the nucleus as an important step in decreased cellular adhesion. The presented data identifies additional details in the regulation of SCC that can aid identification of therapeutic drug targets in the future.

[Epithelial-mesenchymal transition and tumor metastasis]

Metastasis is the transfer of malignant tumors from one organ to a distant organ. It is the most common cause of death in cancer patients. Different molecular mechanisms enable tumor cells to infiltrate the surrounding tissue, invade blood vessels and leave the blood stream at a different site. Epithelial-mesenchymal transition (EMT) is critical for appropriate embryonic development, and this process is re-engaged in adults during wound healing, tissue regeneration, organ fibrosis, and cancer progression. EMT is the first step in tumor invasion and metastasis. A detailed knowledge of the molecular requirements for EMT in human cancer will help us to better understand tumor progression and to delineate more effective strategies for future therapeutic intervention.

A roundabout way to cancer

The Slit family of secreted proteins and their transmembrane receptor, Robo, were originally identified in the nervous system where they function as axon guidance cues and branching factors during development. Since their discovery, a great number of additional roles have been attributed to Slit/Robo signaling, including regulating the critical processes of cell proliferation and cell motility in a variety of cell and tissue types. These processes are often deregulated during cancer progression, allowing tumor cells to bypass safeguarding mechanisms in the cell and the environment in order to grow and escape to new tissues. In the past decade, it has been shown that the expression of Slit and Robo is altered in a wide variety of cancer types, identifying them as potential therapeutic targets. Further, studies have demonstrated dual roles for Slits and Robos in cancer, acting as both oncogenes and tumor suppressors. This bifunctionality is also observed in their roles as axon guidance cues in the developing nervous system, where they both attract and repel neuronal migration. The fact that this signaling axis can have opposite functions depending on the cellular circumstance make its actions challenging to define. Here, we summarize our current understanding of the dual roles that Slit/Robo signaling play in development, epithelial tumor progression, and tumor angiogenesis.

Therapeutic and prognostic importance of epithelial-mesenchymal transition in liver cancers: insights from experimental models

Hepatocellular carcinoma (HCC) and hepatic metastases of colon cancers are malignant conditions of the liver that cause significant morbidity and mortality worldwide. Experimental models suggest that both conditions are characterized by epithelial-mesenchymal transition (EMT). Whilst ongoing research efforts aim to definitively clarify its role in human cancer patients, data from experimental models have unraveled a number of potential therapeutic targets as well as markers of prognostic importance. This area of research is generating intense interest amongst both basic scientists and clinicians. Some questions have been answered, but many important issues remain unresolved. We expect that in the near future, studies of human tissues can definitively clarify the role of EMT in the development and progression of human malignant diseases of the liver and that further studies can be carried out to determine how best to target aspects of the process for the treatment of patients with hepatocellular carcinoma and hepatic metastases of colon cancers.

PTTG induces EMT through integrin αVβ3-focal adhesion kinase signaling in lung cancer cells

Pituitary tumor transforming gene (PTTG) is a well-studied oncogene for its role in tumorigenesis and serves as a marker of malignancy in several cancer types including lung. In the present study, we defined the role of PTTG in actin cytoskeleton remodeling, cell migration and induction of epithelial mesenchymal transition (EMT) through the regulation of integrin α(V)β(3)-FAK (focal adhesion kinase) signaling pathway. Overexpression of PTTG through an adenovirus vector resulted in a significant increase in the expression of integrins α(V) and β(3), a process that was reversed with the downregulation of PTTG expression through the use of an adenovirus expressing PTTG-specific small interfering RNA (siRNA). Western blot analysis of cells infected with adenovirus PTTG cDNA resulted in increased FAK and enhanced expression of adhesion complex molecules paxillin, metavincullin, and talin. Furthermore, downstream signaling genes Rac1, RhoA, Cdc42 and DOCK180 showed upregulation upon PTTG overexpression. This process was dependent on integrin α(V), as blockage by antagonist echistatin (RGD peptide) or α(V)-specific siRNA resulted in a decrease in FAK and subsequent adhesion molecules. Actin cytoskeleton disruption was detected as a result of integrin-FAK signaling by PTTG as well as enhanced cell motility. Taken together, our results suggest for the first time an important role of PTTG in regulation of integrins α(V) and β(3) and adhesion-complex proteins leading to induction of EMT.

Aberrant β-catenin expression in the histologic differentiation of oral squamous cell carcinoma and verrucous carcinoma: an immunohistochemical study

β-Catenin acts as a structural protein at cell-cell adherens junctions and as a transcription activator mediating Wnt signal transduction. Altered β-catenin expression has been associated with loss of cell differentiation and acquisition of an invasive phenotype. In the present study, β-catenin expression was compared immunohistochemically between oral squamous cell carcinoma (30 cases) and verrucous carcinoma (30 cases), and correlated with different histological grades of oral squamous cell carcinoma. Positivity for β-catenin was seen in 17 cases (56.6%) of oral squamous cell carcinoma and 25 cases (83.3%) of verrucous carcinoma, and was significantly correlated with the grade of oral squamous cell carcinoma, whereas no significant correlation of β-catenin expression was observed between oral squamous cell carcinoma and verrucous carcinoma. In oral squamous cell carcinoma, the number of β-catenin-positive cases and the intensity of expression decreased as cancers became more poorly differentiated. Decreased membranous localization and intense cytoplasmic staining were observed in poorly differentiated squamous cell carcinoma. In verrucous carcinoma, β-catenin was demonstrable mainly in the membrane. Down-regulation of β-catenin was significantly correlated with lack of differentiation in oral squamous cell carcinoma. Reduced membranous expression and predominant cytoplasmic localization were prominent among higher-grade tumors, suggesting stabilization of β-catenin and its role as a signaling molecule. Predominant membranous expression in verrucous carcinoma was similar to that observed in well differentiated squamous cell carcinoma, thus corroborating its role in cell adhesion in these subgroups.

Role of Estrogen Receptor-α in the Regulation of Claudin-6 Expression in Breast Cancer Cells

Purpose

In our previous studies we showed that upregulating claudin-6 (CLDN6) expression may contribute to preventing breast cancer, and that 17β-estradiol induces a concentration- and time-related effect on CLDN6 mRNA and protein expression in MCF-7 cells. However, the mechanisms of 17β-estradiol regulation of CLDN6 are still unclear. We determined the role of estrogen receptors in the regulation of CLDN6 expression in human breast cancer tissues and a cell line.

Methods

CLDN6, estrogen receptor alpha (ERα) and estrogen receptor beta (ERβ) expression in breast cancer tissues were examined using immunohistochemistry. The human breast cancer cell line, MCF-7, which expresses ERα but not ERβ was used. CLDN6 and ERα expression were measured by reverse transcriptase-PCR, Western blotting and immunofluorescent staining. Treatments with propyl pyrazole triol (PPT) and ICI 182, 780 (ICI) were performed.

Results

The results revealed that CLDN6 expression was related to ERα in breast cancer tissues (p=0.033). PPT, an ERα-selective ligand, upregulated CLDN6 expression at 10^-5 mol/L after 24 hours. The effect of PPT on regulating CLDN6 expression in MCF-7 cells was blocked by ICI.

Conclusion

These findings suggest that Erα reulates CLDN6 expression in breast cancer tissues and that 17β-estradiol induces CLDN6 expression through an ERα pathway in MCF-7 cells.

Pancreatic stellate cells promote epithelial-mesenchymal transition in pancreatic cancer cells

The interaction between pancreatic cancer cells and pancreatic stellate cells (PSCs), a major profibrogenic cell type in the pancreas, is receiving increasing attention. There is accumulating evidence that PSCs promote the progression of pancreatic cancer by increasing cancer cell proliferation and invasion as well as by protecting them from radiation- and gemcitabine-induced apoptosis. Because epithelial-mesenchymal transition (EMT) plays a critical role in the progression of pancreatic cancer, we hypothesized that PSCs promote EMT in pancreatic cancer cells. Panc-1 and SUIT-2 pancreatic cancer cells were indirectly co-cultured with human PSCs isolated from patients undergoing operation for pancreatic cancer. The expression of epithelial and mesenchymal markers was examined by real-time PCR and immunofluorescent staining. The migration of pancreatic cancer cells was examined by scratch and two-chamber assays. Pancreatic cancer cells co-cultured with PSCs showed loose cell contacts and a scattered, fibroblast-like appearance. The expression of E-cadherin, cytokeratin 19, and membrane-associated β-catenin was decreased, whereas vimentin and Snail (Snai-1) expression was increased more in cancer cells co-cultured with PSCs than in mono-cultured cells. The migration of pancreatic cancer cells was increased by co-culture with PSCs. The PSC-induced decrease of E-cadherin expression was not altered by treatment with anti-TGF-β-neutralizing antibody, excluding a central role of TGF-β in this process. In conclusion, PSCs promoted EMT in pancreatic cancer cells suggesting a novel mechanism by which PSCs contribute to the aggressive behavior of pancreatic cancer cells.

Effects of asbestiform antigorite on human alveolar epithelial A549 cells: a morphological and immunohistochemical study

The purpose of the study was to investigate the biological risk of asbestiform antigorite, which is a fibrous variety of antigorite, one of the natural mineral fibres of the serpentine group to which asbestos chrysotile belongs. Asbestiform antigorite is very abundant and commonly found associated with asbestos chrysotile in serpentinites, a kind of rock outcropping present in many geographical locations worldwide. In this study we evaluated the morphological, immunohistochemical and functional effects of antigorite fibres in alveolar epithelial cancer cells (A549), a standardized human cell line currently used as a model to study cytotoxicity induced by pharmacological agents. The antigorite fibres were identified and characterized morphologically and chemically by X-ray powder diffractometry, transmission and scanning electron microscopy, both with annexed energy dispersive spectrometry. The effects of 50 microg/ml of antigorite in A549 lung cells treated at 24 and 48 h resulted in increased synthesis of VEGF, Cdc42 and beta-catenin that represent potential risks for cancer development. Phalloidin labelling showed an irregular distribution of filamentous actin resulting from antigorite contact. Our studies indicate potential cellular toxicity of antigorite in vivo, providing the opportunity to elucidate the effect of asbestos on cancer induction and possible modes of therapy.

Expression of periostin in the serum of NSCLC and its function on proliferation and migration of human lung adenocarcinoma cell line (A549) in vitro

Periostin is over expressed in many epithelial malignant cancers, including lung cancer, breast cancer, ovarian cancer and colon cancer. It is related with the progression and migration of breast and ovarian cancer cells in vitro. The aim of this study was to investigate the serum level of periostin in non-small cell lung cancer (NSCLC) and its relationship with established biological and prognostic factors by enzyme-linked-immunosorbent serologic assay. We also observe the function of periostin on the proliferation and migration of human lung adenocarcinoma cell line (A549) and discuss the mechanism. The mean value for serum periostin (POSTN) was elevated in NSCLC patients (242.84 + or - 5.33 pg/ml) compared to the normal healthy volunteers (215.66 + or - 11.67 pg/ml) (p = 0.030). The serum level of periostin of NSCLC patients had no connection with gender, age, pathological type, TNM stage, lymph node status, tumor size and invasiveness. We constructed a plasmid named pEGFP-N1/POSTN expressing full-length human periostin. Transfecting the plasmid to A549 cells and periostin was efficiently expressed in transfected A549 cells. Our data showed that periostin could promote the proliferation and migration of A549 cells by inducing vimentin and N-cadherin expression and downregulating E-cadherin expression. These results strongly suggest that periostin is a novel molecular which play an important role during the progression and development of NSCLC.

Global transcriptional characterization of a mouse pulmonary epithelial cell line for use in genetic toxicology

Prior to its application for in vitro toxicological assays, thorough characterization of a cell line is essential. The present study uses global transcriptional profiling to characterize a lung epithelial cell line (FE1) derived from MutaMouse [White, P.A., Douglas, G.R., Gingerich, J., Parfett, C., Shwed, P., Seligy, V., Soper, L., Berndt, L., Bayley, J., Wagner, S., Pound, K., Blakey, D., 2003. Development and characterization of a stable epithelial cell line from Muta Mouse lung. Environmental and Molecular Mutagenesis 42, 166-184]. Results presented here demonstrate the origin of the FE1 lung cell line as epithelial, presenting both type I and type II alveolar phenotype. An assessment of toxicologically-relevant genes, including those involved in the response to stress and stimuli, DNA repair, cellular metabolism, and programmed cell death, revealed changes in expression of 22-27% of genes in one or more culture type (proliferating and static FE1 cultures, primary epithelial cultures) compared with whole lung isolates. Gene expression analysis at 4 and 24h following benzo(a)pyrene exposure revealed the induction of cyp1a1, cyp1a2, and cyp1b1 in FE1 cells and lung isolates. The use of DNA microarrays for gene expression profiling allows an improved understanding of global, coordinated cellular events arising in cells under different physiological conditions. Taken together, these data indicate that the FE1 cell line is derived from a cell type relevant to toxic responses in vivo, and shows some similarity in response to chemical insult as the original tissue.

Prognostic significance of epithelial-mesenchymal and mesenchymal-epithelial transition protein expression in non-small cell lung cancer

PURPOSE

In carcinomas, invasive tumor growth is accompanied by desmoplastic stroma reaction and facilitated by epithelial-mesenchymal transition (EMT) of cancer cells. We investigated the prognostic significance of the EMT indicator proteins periostin and vimentin in comparison with versican, a putative indicator of the opposite mechanism mesenchymal-epithelial transition (MET), and to the desmoplasia proteins collagen and elastin in non-small cell lung cancer (NSCLC).

EXPERIMENTAL DESIGN

Tumor of 533 patients with surgically resected NSCLC was used for analysis of stromal and epithelial protein expression by immunohistochemistry (EMT-MET proteins) and Elastica van Gieson histochemical staining (collagen and elastin). A semiquantitative sum scoring system was done on three tissue microarrays.

RESULTS

Of the 533 patients, 48% had squamous cell carcinoma, 47% adenocarcinoma, and 5% adenosquamous carcinoma. High expression of periostin in either stroma or tumor epithelia, independently scored by two pathologists, correlated with male gender, higher stage, higher pT category, and larger tumor size, and in only stroma with tumor relapse. High expression of versican in either stroma or epithelia as well as of stromal collagen had fewer but concordant associations with advanced tumor and periostin, respectively. High expression of elastin was oppositely associated with less advanced disease. Associations of high vimentin were inconsistent (all P values < 0.05). High stromal periostin was found to be a prognostic factor for decreased progression-free survival on univariate analysis (P = 0.007).

CONCLUSIONS

Because up-regulation is frequently observed in the stromal and epithelial tumor compartment, EMT-MET indicator proteins may be integrated in progression models of NSCLC.

Analysis of APC, alpha-, beta-catenins, and N-cadherin protein expression in aggressive fibromatosis (desmoid tumor)

The aims of this study were to analyze the cadherin/catenin adhesion complex in cells from abdominal and extra-abdominal aggressive fibromatosis tumors, and to estimate the correlation between the expression of the tested proteins and the clinical data of the desmoid patients. Immunohistochemistry was used to examine the expression of the cadherin/catenin adhesion complex: APC protein, alpha-, beta-catenin, and N-cadherin in archival material derived from 15 cases of extra-abdominal desmoid tumor (E-AD) and 20 cases of abdominal (AD) desmoid tumor. The tested proteins demonstrated cytoplasmic (c) staining. Furthermore, nuclear (n) or cytoplasmic and nuclear (c+n) staining was observed for beta-catenin. The mean values of the percentage of positive cells for the tested proteins between E-AD vs. AD did not demonstrate any statistically significant difference except for alpha-catenin. In the E-AD group, in both cases of recurrent tumors, no alpha-catenin expression was observed but the expression of this protein was detected in primary tumors. In the groups investigated, no statistically significant correlation was found between alpha-catenin, beta-catenin (c), (n) and (c+n) expression, and tumor size (p>0.1). The results regarding beta-catenin expression obtained in our study confirm the previous findings that nuclear accumulation of this protein plays a crucial role in the pathogenesis of aggressive fibromatosis.

Claudin-1 Protein Expression is a Prognostic Marker of Patient Survival in Renal Cell Carcinomas

Purpose: Claudin-1 is a tight junction protein described in normal tissues as well as in malignancies. We aimed to assess the diagnostic or prognostic significance of claudin-1 expression in renal cell carcinoma and to correlate the expression of claudin-1 with clinical, histopathologic, and prognostic parameters in renal cell carcinoma.

Experimental Design: A tissue microarray was constructed using formalin-fixed, paraffin-embedded tissue from renal cell carcinomas and corresponding normal renal tissue from 318 patients. The protein expression of claudin-1 was assessed and correlated to clinicopathologic tumor parameters including patient survival. A separate cohort of 44 papillary renal cell carcinoma was used for validation of results.

Results: Claudin-1 was expressed in 29.9% of renal cell cancer cases. Whereas the vast majority of clear cell carcinomas were negative for claudin-1, most papillary tumors (76-86%) were positive. Claudin-1 expression was associated with markers of unfavorable tumor biology in clear cell renal cell carcinoma, whereas the opposite was valid for papillary renal cell carcinoma. In clear cell renal cell carcinoma claudin-1 positivity was a prognosticator of shortened disease-specific patient survival in univariate analysis (P = 0.008), which also remained significant in multivariate analyses in the clinically important subgroups of nonmetastasized or asymptomatic patients.

Conclusions: Claudin-1 is expressed in the majority of papillary renal cell carcinomas, suggesting a diagnostic value of this marker. Its expression is an independent prognosticator of shortened disease-specific patient survival in clinically relevant subgroups of clear cell renal cell carcinoma. Further functional studies are needed to clarify the different biological roles of claudin-1 expression in these histologic subtypes of renal cell carcinoma.

Dog as model for down-expression of E-cadherin and beta-catenin in tubular epithelial cells in renal fibrosis

Mechanism of renal fibrosis leading to end stage kidney remains still a challenge of interest in humans. The pathogenesis of chronic kidney disease is characterized by progressive loss of kidney function and fibrosis. The mechanism of epithelial-mesenchymal transition (EMT) has been predominantly studied in in vitro studies, and we previously demonstrated the EMT of tubular epithelial cells in dogs. In this study, we examined and quantified the modifications of cadherin-catenin complex by immunohistochemistry of E-cadherin and beta-catenin and the mesenchymal marker vimentin in 25 dogs with three different spontaneous inflammatory renal diseases. Results showed a significant down-expression of levels of E-cadherin and beta-catenin directly correlated with the tubular-interstitial damage (TID). In TID grades 2 and 3, E-cadherin expression was significantly reduced (p < 0.001). beta-catenin expression was overall similar to E-cadherin. The mesenchymal-associated protein, vimentin, was de novo identified in tubules within areas of inflammation. In this work, we identified the loss of cadherin or catenin expression as a progressive mechanism in tubulo-interstitial fibrosis, which allows dissociation of structural integrity of renal epithelia and loss of epithelial polarity. The dog might result more significant as model for new therapies.

Aberrant promoter hypermethylation in serum DNA from patients with silicosis

It is well established that patients with silicosis are at high risk for lung cancer; however, it is difficult to detect lung cancer by chest radiography during follow-up treatment of patients with silicosis because of preexisting diffuse pulmonary shadows. The purpose of this study is to evaluate the usefulness of detection of serum DNA methylation for early detection of lung cancer in silicosis. Serum samples from healthy controls (n = 20) and silicosis patients with (n = 11) and without (n = 67) lung cancer were tested for aberrant hypermethylation at the promoters of the DNA repair gene O(6)-methylguanine-DNA methyltransferase (MGMT), p16(INK4a), ras association domain family 1A (RASSF1A), the apoptosis-related gene death-associated protein kinase (DAPK) and retinoic acid receptor beta (RARbeta) by methylation-specific polymerase chain reaction. Aberrant promoter methylation in at least one of five tumor suppressor genes was detected more frequently in the serum DNA of silicosis patients with lung cancer than in that of patients without it (P = 0.006). Furthermore, the odds ratio of having lung cancer was 9.77 (P = 0.009) for those silicosis patients with methylation of at least one gene. Extended exposure to silica (>30 years) was correlated with an increased methylation frequency (P = 0.017); however, methylation status did not correlate with age, smoking history or radiographic findings of silicosis. These results suggest that testing for aberrant promoter methylation of tumor suppressor genes using serum DNA may facilitate early detection of lung cancer in patients with silicosis.

Proteomic analysis of stage I primary lung adenocarcinoma aimed at individualisation of postoperative therapy

Although postoperative adjuvant chemotherapy (PAC) with uracil–tegafur significantly improves the prognosis of patients with stage I lung adenocarcinoma, subset analysis has revealed that only 11.5% of patients with stage IB derive actual benefit from such therapy. Therefore, it is extremely important to identify patients for whom adjuvant chemotherapy will be beneficial. We performed comprehensive protein analysis of 24 surgically resected specimens of stage I adenocarcinoma using liquid chromatography-tandem mass spectrometry (LC-MS/MS), followed by bioinformatical investigations to identify protein molecules. Furthermore, we carried out immunohistochemical studies of 90 adenocarcinoma specimens to validate the results of LC-MS/MS. We detected two kinds of protein molecules (myosin IIA and vimentin) by LC-MS/MS. We confirmed their immunohistochemical expression and distribution, and evaluated the relationship between the expression of these proteins and prognosis after adjuvant chemotherapy. Patients with no expression of either myosin IIA or vimentin showed a significantly better outcome regardless of PAC using uracil–tegafur. However, we were unable to select responders to uracil–tegafur using these proteins. Cases of adenocarcinoma lacking expression of either myosin IIA or vimentin show a good outcome without PAC, and therefore do not require such treatment.

Molecular analysis of a multistep lung cancer model induced by chronic inflammation reveals epigenetic regulation of p16 and activation of the DNA damage response pathway

The molecular hallmarks of inflammation-mediated lung carcinogenesis have not been fully clarified, mainly due to the scarcity of appropriate animal models. We have used a silica-induced multistep lung carcinogenesis model driven by chronic inflammation to study the evolution of molecular markers and genetic alterations. We analyzed markers of DNA damage response (DDR), proliferative stress, and telomeric stress: gamma-H2AX, p16, p53, and TERT. Lung cancer-related epigenetic and genetic alterations, including promoter hypermethylation status of p16(CDKN2A), APC, CDH13, Rassf1, and Nore1A, as well as mutations of Tp53, epidermal growth factor receptor, K-ras, N-ras, and c-H-ras, have been also studied. Our results showed DDR pathway activation in preneoplastic lesions, in association with inducible nitric oxide synthase and p53 induction. p16 was also induced in early tumorigenic progression and was inactivated in bronchiolar dysplasias and tumors. Remarkably, lack of mutations of Ras and epidermal growth factor receptor, and a very low frequency of Tp53 mutations suggest that they are not required for tumorigenesis in this model. In contrast, epigenetic alterations in p16(CDKN2A), CDH13, and APC, but not in Rassf1 and Nore1A, were clearly observed. These data suggest the existence of a specific molecular signature of inflammation-driven lung carcinogenesis that shares some, but not all, of the molecular landmarks of chemically induced lung cancer.

Bone morphogenetic protein 4 induces epithelial-mesenchymal transition through MSX2 induction on pancreatic cancer cell line

In our study, we found that bone morphogenetic protein 4 (BMP4) has a novel effect as an inducer of epithelial-mesenchymal transition (EMT) on Panc-1 cells, a human pancreatic carcinoma cell line. BMP4-treated Panc-1 cells showed loose cell contacts and a scattered, fibroblast-like appearance along with E-cadherin downregulation, Vimentin upregulation and enhanced cell migration, which are characteristic of EMT. BMP4 treatment also induced homeobox gene MSX2 expression, which we previously showed to be associated with EMT in pancreatic carcinoma cells. BMP4 treatment activated the Smad signaling pathway, and extracellular signal-related kinase (ERK) and p38 mitogen-activated kinase (MAPK) pathways in these cells. MSX2 was markedly induced by BMP4 through the ERK and p38 MAPK pathways in collaboration with the Smad signaling pathway. The repression of E-cadherin, induction of Vimentin and enhanced cell migration disappeared when siRNA-based MSX2 downregulated pancreatic cancer cells were treated with BMP4. These findings indicate that BMP4 may be involved in pancreatic carcinoma development through the promotion of EMT and that MSX2 is indispensable to this process.

Poly(ADP-ribose) polymerase-1 regulates vimentin expression in lung cancer cells

Vimentin is one of the mammalian intermediate filament proteins. It is expressed in cells of mesenchymal origin and is characteristic of proliferating cells at the fetal stage. During malignancy, vimentin expression is activated in certain lung epithelial cells. Examination of a group of lung cancer cells showed a marked difference in their vimentin expression. The difference in vimentin expression among lung cancer cells is due to differential regulation at the transcriptional level. Analysis of the vimentin promoter revealed a 102-bp promoter sequence that is important for promoter activity in a lung cancer cell line in which vimentin is strongly expressed. This promoter region interacts with poly(ADP-ribose) polymerase-1 (PARP-1), which is also a transcription regulator. Exogenous expression of PARP-1 increased vimentin promoter activity. A shortened PARP-1 without the COOH-terminal catalytic domain showed the same promoter activation effect. Treatment of cells with H(2)O(2) reduced PARP-1 and vimentin expression at the protein level. H(2)O(2) also dose dependently suppressed vimentin promoter activity in cells overexpressing PARP-1. These results demonstrate that vimentin expression in lung cancer cells is regulated at the transcriptional level and that PARP-1 binds and activates the vimentin promoter independent of its catalytic domain and may play a role in H(2)O(2)-induced inhibition of vimentin expression.

Perspectives on endothelial-to-mesenchymal transition: potential contribution to vascular remodeling in chronic pulmonary hypertension

All forms of pulmonary hypertension are characterized by structural changes in pulmonary arteries. Increased numbers of cells expressing α-smooth muscle (α-SM) actin is a nearly universal finding in the remodeled artery. Traditionally, it was assumed that resident smooth muscle cells were the exclusive source of these newly appearing α-SM actin-expressing cells. However, rapidly emerging experimental evidence suggests other, alternative cellular sources of these cells. One possibility is that endothelial cells can transition into mesenchymal cells expressing α-SM actin and that this process contributes to the accumulation of SM-like cells in vascular pathologies. We review the evidence that endothelial-mesenchymal transition is an important contributor to cardiac and vascular development as well as to pathophysiological vascular remodeling. Recent work has provided evidence for the role of transforming growth factor-β, Wnt, and Notch signaling in this process. The potential roles of matrix metalloproteinases and serine proteases are also discussed. Importantly, endothelial-mesenchymal transition may be reversible. Thus insights into the mechanisms controlling endothelial-mesenchymal transition are relevant to vascular remodeling and are important as we consider new therapies aimed at reversing pulmonary vascular remodeling.

Cytotoxicity and DNA-damage in human lung epithelial cells exposed to respirable α-quartz

Occupational exposure to respirable crystalline silica is associated with the development of silicosis, lung cancer and airways diseases. In order to assess cytotoxic effects and direct-oxidative DNA damage induced by short-term exposure to different doses of respirable alpha-quartz (NIST SRM1878a), we conducted a study using A549 cells. The cells were exposed to alpha-quartz at 25, 50, 100 microg/ml for 4 h and analysed by scanning electron microscope (SEM) and LDH release assay for cytotoxic effect evaluation. Cells were also exposed to 10, 25, 50, 100 microg/ml of alpha-quartz for 2 h and 4 h and analysed by Fpg comet test to evaluate direct and oxidative DNA damage. SEM observations of treated cells showed bleb development at lower doses and alterations of microvilli morphology at the highest dose. A slight LDH release was found only at 100 microg/ml. Fpg comet test showed a dose-related oxidative DNA damage in cells exposed for 2 h to quartz. Cells exposed for 4h at the same concentrations showed a dose-related direct DNA damage and the presence of oxidative DNA damage at lower doses. The bleb induction on cell surface evidenced by SEM at lower doses correlates with the presence of oxidative DNA damage at 4 h. The cell surface modifications observed by SEM at 100 microg/ml indicate that high doses of quartz induce more evident cytotoxic effects confirmed by LDH analysis and correlate with the genotoxicity showed by comet assay.

The role of epithelial injury and repair in the origins of asthma

PURPOSE OF REVIEW

We currently understand little about the mechanisms that lead to asthma. The bronchial epithelium is the first cell layer of contact with the environment and as such is an especially attractive target in which to identify novel mechanisms and new therapeutic strategies in disease development. We discuss the role of epithelial injury and wound repair in the origins of asthma.

RECENT FINDINGS

The presence of inflammation, thickening of the basement membrane and angiogenesis have been described in bronchial biopsies from asthmatic children. We and others have demonstrated the utility of bronchial brushings from children for the isolation, characterization and culture of primary epithelial cells. The results of these experiments suggest that intrinsic differences exist between asthmatic and nonasthmatic epithelial cells.

SUMMARY

It is becoming increasingly clear from studies involving adults and, more recently, children, that the epithelium orchestrates inflammatory and remodeling responses of the airway. Equally clear is that the asthmatic epithelium responds inappropriately to challenge and displays signs of dysregulated repair. Understanding the regulatory mechanisms involved in these processes, including the role of resident/recruited progenitor cells, is crucial if we are to halt the progression of asthma when the disease first manifests in childhood.

Influence ofKi-ras-driven oncogenic transformation on the protein network of murine fibroblasts

Ki-ras gene mutations that specifically occur in codons 12, 13 and 61 are involved in the carcinogenesis of acute myeloid leukemia, melanoma and different carcinomas. In order to define potential mutation-specific therapeutic targets, stable transfectants of NIH3T3 cells carrying different Ki-ras4B gene mutations were generated. Wild type Ki-ras transformants, mock transfectants and parental cells served as controls. These in vitro model systems were systematically analyzed for their protein expression pattern using two-dimensional gel electrophoresis followed by mass spectrometry and/or protein sequencing. Using this approach, a number of target molecules that are differentially but coordinately expressed in the ras transfectants were identified next to other proteins that exhibit a distinct regulation pattern in the different cell lines analyzed. The differentially expressed proteins predominantly belong to the families of cytoskeletal proteins, heat shock proteins, annexins, metabolic enzymes and oxidoreductases. Their validation was assessed by real-time quantitative RT-PCR and/or Western blot analysis. Our results suggest that the Ki-ras-transformed cells represent a powerful tool to study Ki-ras gene mutation-driven protein expression profiles. In addition, this approach allows the discovery of ras-associated cellular mechanisms, which might lead to the identification of physiological targets for pharmacological interventions of the treatment of Ki-ras-associated human tumors.

Transepithelial leak in Barrett's esophagus

Using orally administered sucrose as a probe of gastrointestinal permeability, this study focused on determining whether Barrett's metaplasia exhibits a paracellular transepithelial leak to small nonelectrolytes. Subjects in five separate classes (nonendoscoped, asymptomatic controls; endoscoped, asymptomatic controls; gastroesophageal reflux disease without mucosal complications; grossly visible esophagitis; and Barrett's esophagus) consumed a sucrose solution at bedtime and collected all overnight urine. Urine volume was measured and sucrose concentration was determined by high-performance liquid chromatography. Patients with Barrett's were observed to exhibit a transepithelial leak to sucrose whose mean value was threefold greater than that seen in healthy control subjects or patients with reflux but without any mucosal defect. A parallel study of claudin tight junction proteins in endoscopy biopsy samples showed that whereas Barrett's metaplasia contains dramatically more claudin-2 and claudin-3 than is found in normal esophageal mucosa, it is markedly lower in claudins 1 and 5, indicating very different tight junction barriers.

Differential protein expression profiling by iTRAQ-2DLC-MS/MS of lung cancer cells undergoing epithelial-mesenchymal transition reveals a migratory/invasive phenotype

Transforming growth factor-beta (TGF-beta) induces epithelial-mesenchymal transition (EMT) of epithelial cells in both normal embryonic development and certain pathological contexts. Here, we show that TGF-beta induced-EMT in human lung cancer cells (A549; adenocarcinoma cells) mediates tumor cell migration and invasion phenotypes. To gain insights into molecular events during EMT, we employed a global stable isotope labeled profiling strategy using iTRAQ reagents, followed by 2DLC-MS/MS, which identified a total of 51 differentially expressed proteins during EMT; 29 proteins were up-regulated and 22 proteins were down-regulated. Down-regulated proteins were predominantly enzymes involved in regulating nutrient or drug metabolism. The majority of the TGF-beta-induced proteins (such as tropomyosins, filamin A, B, & C, integrin-beta1, heat shock protein27, transglutaminase2, cofilin, 14-3-3 zeta, ezrin-radixin-moesin) are involved in the regulation of cell migration, adhesion and invasion, suggesting the acquisition of a invasive phenotype.

DNA-methylation-dependent alterations of claudin-4 expression in human bladder carcinoma

The expression pattern of tight junction (TJ) proteins is frequently disrupted in epithelial tumors. In particular, isoform- and organ-specific alterations of claudins have been detected in human cancers, highlighting them as interesting tools for the prognosis or treatment of various carcinomas. However, the molecular mechanisms responsible for these alterations are seldom identified. Here, we analyzed the expression and localization of claudins 1, 4, and 7 in human bladder carcinoma. Claudin-4 expression was significantly altered in 26/39 tumors, contrasting with the rare modifications detected in the expression of claudins 1 and 7. Overexpression of claudin-4 in differentiated carcinomas was followed by a strong downregulation in invasive/high-grade tumors, and this expression pattern was associated to the 1-year survival of bladder tumor patients. A CpG island was identified within the coding sequence of the CLDN4 gene, and treatment with a methyl-transferase inhibitor restored expression of the protein in primary cultures prepared from high-grade human bladder tumors. In addition, claudin-4 expression correlated with its gene methylation profile in healthy and tumoral bladders from 20 patients, and downregulation of claudin-4 expression was detected in the urothelium of mice overexpressing DNA methyl transferase 3a (Dnmt3a). Delocalization of claudins 1 and 4 from TJs was observed in most human bladder tumors and in the bladder tumor cell line HT-1376. Although the CLDN4 gene was unmethylated in these cells, pharmacological inhibition of methyl transferases re-addressed the two proteins to TJs, resulting in an increase of cell polarization and transepithelial resistance. These biological effects were prevented by expression of claudin-4-specific siRNAs, demonstrating the important role played by claudin-4 in maintaining a functional regulation of homeostasis in urothelial cells. Results of this study indicate that the TJ barrier is disrupted from early stages of urothelial tumorigenesis. In addition, we identified hypermethylation as the mechanism leading to the alteration of claudin-4 expression, and maybe also localization, in bladder carcinoma.

The cardenolide UNBS1450 is able to deactivate nuclear factor kappaB-mediated cytoprotective effects in human non-small cell lung cancer cells

Non-small cell lung cancers (NSCLC) are associated with very dismal prognoses, and adjuvant chemotherapy, including irinotecan, taxanes, platin, and Vinca alkaloid derivatives, offers patients only slight clinical benefits. Part of the chemoresistance of NSCLCs results from the constitutive or anticancer drug-induced activation of the nuclear factor-kappaB (NF-kappaB) signaling pathways. The present study shows that human A549 NSCLC cells display highly activated cytoprotective NF-kappaB signaling pathways. UNBS1450, which is a cardenolide belonging to the same class of chemicals as ouabain and digitoxin, affected the expression and activation status of different constituents of the NF-kappaB pathways in these A549 tumor cells. The modifications brought about by UNBS1450 led to a decrease in both the DNA-binding capacity of the p65 subunit and the NF-kappaB transcriptional activity. Using the 3-(4,5-dimethylthiazol-2yl)-dephenyltetrazolium bromide colorimetric assay, we observed in vitro that UNBS1450 was as potent as taxol and SN38 (the active metabolite of irinotecan) in reducing the overall growth levels of the human A549 NSCLC cell line, and was more efficient than platin derivatives, including cisplatin, carboplatin, and oxaliplatin. The chronic in vivo i.p. and p.o. UNBS1450 treatments of human A549 orthotopic xenografts metastasizing to the brains and the livers of immunodeficient mice had a number of significant therapeutic effects on this very aggressive model.

N-cadherin expression in breast cancer: correlation with an aggressive histologic variant--invasive micropapillary carcinoma

Upregulation of N-cadherin in epithelial tumor cells has been shown to contribute to the invasive/metastatic phenotype. It remains however to be determined whether N-cadherin is increased in human breast cancers with enhanced malignant potential. We examined a large number of invasive breast cancer specimens (n = 114) for N- and E-cadherin. These specimens compared invasive duct carcinomas (IDCs) of varying histologic grades with an aggressive subtype, invasive micropapillary carcinoma of the breast (MPAP), which has a high propensity for lymphatic invasion and lymph node metastasis. Staining scores for N- and E-cadherin were compared between non-MPAP and MPAP IDCs, and between the invasive and ductal carcinoma in situ (DCIS) of each IDC using statistical analysis. We found that N-cadherin was expressed in 76% of MPAP and 52% of non-MPAP carcinomas, and E-cadherin in 57% of MPAP and 36% of non-MPAP tumors. More MPAP (25%) compared to non-MPAP (5%) tumors expressed both cadherins. Of the two cadherins, N-cadherin was significantly associated with MPAP tumors (p = 0.033) compared to E-cad (p = 0.171). Moreover, in the majority of tumors that were positive for N-cadherin, the staining scores were increased in the IDC relative to intraductal components, and this effect was more dramatic in the MPAP carcinomas. This difference for N-cadherin was greater than the corresponding difference for E-cadherin in the MPAP group (p = 0.005), whereas such changes were not significant in the non-MPAP group (p = 0.10). Thus, N-cadherin is associated with tumor aggressiveness and metastatic potential and may contribute to tumor progression.