Loss of tight junction barrier function and its role in cancer metastasis

EMT: Mechanisms and therapeutic implications

Metastasis, the dissemination of cancer cells from primary tumors, represents a major hurdle in the treatment of cancer. The epithelial-mesenchymal transition (EMT) has been studied in normal mammalian development for decades, and it has been proposed as a critical mechanism during cancer progression and metastasis. EMT is tightly regulated by several internal and external cues that orchestrate the shifting from an epithelial-like phenotype into a mesenchymal phenotype, relying on a delicate balance between these two stages to promote metastatic development. EMT is thought to be induced in a subset of metastatic cancer stem cells (MCSCs), bestowing this population with the ability to spread throughout the body and contributing to therapy resistance. The EMT pathway is of increasing interest as a novel therapeutic avenue in the treatment of cancer, and could be targeted to prevent tumor cell dissemination in early stage patients or to eradicate existing metastatic cells in advanced stages. In this review, we describe the sequence of events and defining mechanisms that take place during EMT, and how these interactions drive cancer cell progression into metastasis. We summarize clinical interventions focused on targeting various aspects of EMT and their contribution to preventing cancer dissemination.

Antrodia camphorata inhibits metastasis and epithelial-to-mesenchymal transition via the modulation of claudin-1 and Wnt/β-catenin signaling pathways in human colon cancer cells

ETHNOPHARMACOLOGICAL RELEVANCE

Antrodia camphorata (AC) is a well known traditional Chinese medicinal mushroom in Taiwan, has been used to treat various diseases including cancer.

MATERIALS AND METHODS

In this study, we investigated the anti-metastatic and anti-EMT properties of a fermented culture broth of AC in human colon SW480^claudin-1- and metastatic SW620^claudin-1+ cancer cells in vitro.

RESULTS

AC down-regulates claudin-1 and inhibits the proliferation and colony-formation abilities of both SW620^claudin-1+ and SW480^claudin-1- cells. In highly metastatic SW620^claudin-1+ cells, non-cytotoxic concentrations of AC significantly inhibited migration/invasion, accompanied by the down-regulation of MMP-2 and MMP-9 proteins. AC decreased nuclear translocation of Wnt/β-catenin through a GSK3β-dependent pathway. AC consistently inhibited EMT by up-regulating the epithelial and downregulating the mesenchymal marker proteins. In SW480^claudin-1- cells, AC suppressed migration/invasion potentially through the inhibition of the PI3K/AKT/NFκB signaling pathways without altering the expression levels of β-catenin and GSK3β proteins.

CONCLUSION

Altogether, this study demonstrates the anti-metastatic and anti-EMT activities of AC, which may contribute to the development of a chemopreventive agent for colon cancer.

Non-thermal plasma-treated solution demonstrates antitumor activity against pancreatic cancer cells in vitro and in vivo

Pancreatic cancer is associated with a high mortality rate. In advanced stage, patients often experience peritoneal carcinomatosis. Using a syngeneic murine pancreatic cancer cell tumor model, the effect of non-thermal plasma (NTP) on peritoneal metastatic lesions was studied. NTP generates reactive species of several kinds which have been proven to be of relevance in cancer. In vitro, exposure to both plasma and plasma-treated solution significantly decreased cell viability and proliferation of 6606PDA cancer cells, whereas mouse fibroblasts were less affected. Repeated intraperitoneal treatment of NTP-conditioned medium decreased tumor growth in vivo as determined by magnetic resonance imaging, leading to reduced tumor mass and improved median survival (61 vs 52 days; p < 0.024). Tumor nodes treated by NTP-conditioned medium demonstrated large areas of apoptosis with strongly inhibited cell proliferation. Contemporaneously, no systemic effects were found. Apoptosis was neither present in the liver nor in the gut. Also, the concentration of different cytokines in splenocytes or blood plasma as well as the distribution of various hematological parameters remained unchanged following treatment with NTP-conditioned medium. These results suggest an anticancer role of NTP-treated solutions with little to no systemic side effects being present, making NTP-treated solutions a potential complementary therapeutic option for advanced tumors.

Influence of microenvironment topography and stiffness on the mechanics and motility of normal and cancer renal cells

The tumor microenvironment highly influences cancer cell modes and dynamics, above all during invasive and metastatic processes. When aiming at studying cancer cell behavior in vitro, the use of conventional cell culture systems, such as Petri dishes, fails in recapitulating the mechanical and topographical properties of the natural extracellular matrix (ECM). Here the versatility of stiffness-tunable hydrogels and the efficacy of the replica molding technique with silicone polymers are exploited, aiming at studying cancer and normal cell behavior with platforms able to capture the heterogeneities of the natural in vivo context. We compared the mechanical properties of normal and cancer renal cells on different stiffness value gels (with Young's moduli of 3, 17 and 31 kPa) by using atomic force microscopy (AFM) and investigated cell indentation phenomena on compliant gels with confocal microscopy. Moreover, we studied cell mechanics, morphology and migration on isotropic linear structures, spaced at 1.5 μm, aiming at mimicking the aligned fiber bundles typically observed at tumor borders. By using this approach, we could highlight differences in the way healthy and cancer renal cells react to changes in their microenvironment. Our results may potentially pave the way to unravel the complex processes involved in cancer progression, especially in tissue invasion and migration during metastasis formation.

RBM38 is involved in TGF-β-induced epithelial-to-mesenchymal transition by stabilising zonula occludens-1 mRNA in breast cancer

BACKGROUND

The transforming growth factor-β (TGF-β) pathway plays a vital role in driving cancer cell epithelial-mesenchymal transition (EMT). Zonula occludens-1 (ZO-1), which is downregulated in response to TGF-β, is able to control endothelial cell-cell tension, cell migration, and barrier formation. However, the molecular mechanism of how TGF-β regulates ZO-1 expression remains unclear.

METHODS

Breast cancer cells were treated with TGF-β to induce an EMT progress. Chromatin immunoprecipitation and dual-luciferase reporter assay were performed to investigate direct relationship between Snail and RNA binding motif protein 38 (RBM38). The RNA immunoprecipitation combined with RNA electrophoretic mobility shift assay and dual-luciferase reporter assay were conducted to testify direct relationship between RBM38 and ZO-1. The ZO-1 siRNA was transfected to breast cancer cells that overexpress RBM38 and the control, followed by transwell and Matrigel invasion assays to examine cell migratory and invasive ability.

RESULTS

Transforming growth factor-β induced a remarkable downregulation of RBM38 in breast cancer that was directly regulated by transcription repressor Snail targeting the E-box elements in promoter region of RBM38 gene. Additionally, RBM38 positively regulated ZO-1 transcript via directly binding to AU/U-rich elements in its mRNA 3'-UTR. Moreover, by magnifying RBM38 expression, cell migration and invasion mediated by knockdown of ZO-1 in breast cancer were reversed.

CONCLUSIONS

All the results clarified a linear regulation relationship among Snail, RBM38, and ZO-1, implicating RBM38 as a pivotal mediator in TGF-β-induced EMT in breast cancer.

Toxicity and Immunogenicity in Murine Melanoma following Exposure to Physical Plasma-Derived Oxidants

Metastatic melanoma is an aggressive and deadly disease. Therapeutic advance has been achieved by antitumor chemo- and radiotherapy. These modalities involve the generation of reactive oxygen and nitrogen species, affecting cellular viability, migration, and immunogenicity. Such species are also created by cold physical plasma, an ionized gas capable of redox modulating cells and tissues without thermal damage. Cold plasma has been suggested for anticancer therapy. Here, melanoma cell toxicity, motility, and immunogenicity of murine metastatic melanoma cells were investigated following plasma exposure in vitro. Cells were oxidized by plasma, leading to decreased metabolic activity and cell death. Moreover, plasma decelerated melanoma cell growth, viability, and cell cycling. This was accompanied by increased cellular stiffness and upregulation of zonula occludens 1 protein in the cell membrane. Importantly, expression levels of immunogenic cell surface molecules such as major histocompatibility complex I, calreticulin, and melanocortin receptor 1 were significantly increased in response to plasma. Finally, plasma treatment significantly decreased the release of vascular endothelial growth factor, a molecule with importance in angiogenesis. Altogether, these results suggest beneficial toxicity of cold plasma in murine melanomas with a concomitant immunogenicity of potential interest in oncology.

Roles of Thyroid Transcription Factor 1 in Lung Cancer Biology

Thyroid transcription factor 1 (TTF-1 or NKX2-1) is a transcription factor of fundamental importance in driving lung maturation and morphogenesis. In the last decade, scientists began to appreciate the functional roles of TTF-1 in lung tumorigenesis. This movement was triggered by the discoveries of genetic alterations of TTF-1 in the form of gene amplification in lung cancer. Many downstream target genes of TTF-1 relevant to the lung cancer biology of TTF-1 have been documented. One of the most surprising findings was that TTF-1 may exhibit either pro- or antitumorigenic activities, an outcome with the complexity exceeding the original anticipation purely based on the fact that TTF-1 undergoes gene amplification in lung cancer. In the coming decade, we believe, we will witness additional surprises as the research exploring the cancer roles of TTF-1 progresses.

Curcumin Inhibits LIN-28A through the Activation of miRNA-98 in the Lung Cancer Cell Line A549

Metastasis is common in lung cancer and is associated with poor clinical outcomes and increased mortality. Curcumin is a natural anti-cancer agent that inhibits the metastasis of various cancers by modulating the expression of micro (mi) RNAs such as miR-98, which acts as a tumor suppressor. This study investigated the effect of curcumin on miR-98 expression and in vitro cell line growth and invasiveness in lung cancer. Curcumin treatment enhanced the expression of miR-98 and reduced that of the miR-98 target gene LIN28A as well as matrix metalloproteinase (MMP) 2 and MMP9 in vitro and in vivo. MiR-98 overexpression suppressed lung cancer cell migration and invasion by inhibiting LIN28A-induced MMP2 and MMP9 expression. Meanwhile, LIN28A level was downregulated by overexpression of miR-98 mimic. Induction of miR-98 by curcumin treatment suppressed MMP2 and MMP9 by targeting LIN28A. These findings provide insight into the mechanisms by which curcumin suppresses lung cancer cell line growth in vitro and in vivo and invasiveness in vitro.

The Role of Probiotics in Cancer Treatment: Emphasis on their In Vivo and In Vitro Anti-metastatic Effects

Probiotics are defined as live bacteria and yeasts that exert beneficial effects for health. Among their various effects, anti-cancer properties have been highlighted in recent years. Such effects include suppression of the growth of microbiota implicated in the production of mutagens and carcinogens, alteration in carcinogen metabolism and protection of DNA from oxidative damage as well as regulation of immune system. We performed a computerized search of the MEDLINE/PUBMED databases with key words: cancer, probiotics, lactobacilli, metastasis and invasion. Cell line studies as well as animal models and human studies have shown the therapeutic effects of probiotics in reduction of invasion and metastasis in cancer cells. These results support the beneficial effects of probiotics both in vitro and in vivo. However, pre-clinical or clinical studies are not enough to decide about their application.

Epithelial-to-mesenchymal transition in tumor progression

The epithelial-to-mesenchymal transition (EMT) is a biological process in which a non-motile epithelial cell changes to a mesenchymal state with invasive capacities. However, the EMT program is involved in both physiological and pathological processes. Cancer-associated EMT is known to contribute to increase invasiveness and metastasis, resistance to therapies, and generation of cell populations with stem cell-like characteristics and therefore is deeply involved in tumor progression. This process is finely orchestrated by multiple signaling pathways and regulatory transcriptional networks. The hallmark of EMT is the loss of epithelial surface markers, mainly E-cadherin, and the acquisition of mesenchymal phenotype. These events can be mediated by EMT transcription factors which can cooperate with several enzymes to repress the E-cadherin expression and regulate EMT at the epigenetic and post-translational level. A growing body of evidence indicates that cancer cells can reside in various phenotypic states along the EMT spectrum, where cells can jointly retain epithelial traits with mesenchymal ones. This type of phenotypic plasticity endows cancer cells with tumor-initiating potential. The identification of the signaling pathways and modulators that lead to activation of EMT programs during these disease processes is providing new insights into the plasticity of cellular phenotypes and possible therapeutic interventions.

Metadherin regulates actin cytoskeletal remodeling and enhances human gastric cancer metastasis via epithelial-mesenchymal transition

Metadherin (MTDH) can be recruited to mature tight junction complexes, and it regulates mesenchymal marker protein expression in many tumors and promote cancer metastasis. This study investigated the influence of MTDH expression on gastric cancer and to elucidate the potential mechanisms by which MTDH regulates actin cytoskeletal remodeling and enhances human gastric cancer metastasis via epithelial-mesenchymal transition (EMT). Relative MTDH mRNA expression levels were assessed by quantitative real-time PCR (Q-PCR), and MTDH protein expression levels and localization were evaluated via immunohistochemical (ICH) staining. We studied the role of MTDH in cancer cell migration and invasion by modulating MTDH expression in the gastric cancer cell lines MKN45 and AGS. We also confirmed the functions of MTDH through in vivo experiments. We found that MTDH expression levels were correlated with lymph node metastasis, TNM stages and decreased OS (P=0.002, <0.001 and 0.010, respectively) in human gastric cancer and that MTDH upregulation promoted EMT in vitro. Consistent with this finding, MTDH downregulation inhibited cell migration and invasion in vitro and suppressed tumor growth and metastasis in vivo. Furthermore, MTDH knockdown regulated actin cytoskeletal remodeling and inhibited EMT. Overall, our results provide a novel role for MTDH in regulating gastric cancer metastasis.

Calcitonin receptor increases invasion of prostate cancer cells by recruiting zonula occludens-1 and promoting PKA-mediated TJ disassembly

Almost all primary prostate cancers (PCs) and PC cell lines express calcitonin (CT) and/or its receptor (CTR), and their co-expression positively correlates with their invasiveness. Activation of the CT-CTR axis in non-invasive LNCaP cells induces an invasive phenotype. In contrast, silencing of CT/CTR expression in highly metastatic PC-3M cells markedly reduces their tumorigenicity and abolishes their ability to form distant metastases in nude mice. Our recent studies suggest that CTR interacts with zonula occludens 1 (ZO-1) through PDZ interaction to destabilize tight junctions and increase invasion of PC cells. Our results show that CTR activates AKAP2-anchored cAMP-dependent protein kinase A, which then phosphorylates tight junction proteins ZO-1 and claudin 3. Moreover, PKA-mediated phosphorylation of tight unction proteins required CTR-ZO-1 interaction, suggesting that the interaction may bring CTR-activated PKA in close proximity of tight junction proteins. Furthermore, inhibition of PKA activity attenuated CT-induced loss of TJ functionality and invasion, suggesting that the phosphorylation of TJ proteins is responsible for TJ disassembly. Finally, we show that the prevention of CTR-ZO-1 interaction abolishes CT-induced invasion, and can serve as a novel therapeutic tool to treat aggressive prostate cancers. In brief, the present study identifies the significance of CTR-ZO-1 interaction in progression of prostate cancer to its metastatic form.

Melatonin, a Full Service Anti-Cancer Agent: Inhibition of Initiation, Progression and Metastasis

There is highly credible evidence that melatonin mitigates cancer at the initiation, progression and metastasis phases. In many cases, the molecular mechanisms underpinning these inhibitory actions have been proposed. What is rather perplexing, however, is the large number of processes by which melatonin reportedly restrains cancer development and growth. These diverse actions suggest that what is being observed are merely epiphenomena of an underlying more fundamental action of melatonin that remains to be disclosed. Some of the arresting actions of melatonin on cancer are clearly membrane receptor-mediated while others are membrane receptor-independent and involve direct intracellular actions of this ubiquitously-distributed molecule. While the emphasis of melatonin/cancer research has been on the role of the indoleamine in restraining breast cancer, this is changing quickly with many cancer types having been shown to be susceptible to inhibition by melatonin. There are several facets of this research which could have immediate applications at the clinical level. Many studies have shown that melatonin's co-administration improves the sensitivity of cancers to inhibition by conventional drugs. Even more important are the findings that melatonin renders cancers previously totally resistant to treatment sensitive to these same therapies. Melatonin also inhibits molecular processes associated with metastasis by limiting the entrance of cancer cells into the vascular system and preventing them from establishing secondary growths at distant sites. This is of particular importance since cancer metastasis often significantly contributes to death of the patient. Another area that deserves additional consideration is related to the capacity of melatonin in reducing the toxic consequences of anti-cancer drugs while increasing their efficacy. Although this information has been available for more than a decade, it has not been adequately exploited at the clinical level. Even if the only beneficial actions of melatonin in cancer patients are its ability to attenuate acute and long-term drug toxicity, melatonin should be used to improve the physical wellbeing of the patients. The experimental findings, however, suggest that the advantages of using melatonin as a co-treatment with conventional cancer therapies would far exceed improvements in the wellbeing of the patients.

Tumour blood vessel normalisation by prolyl hydroxylase inhibitor repaired sensitivity to chemotherapy in a tumour mouse model

Blood vessels are important tissue structures that deliver oxygen and nutrition. In tumour tissue, abnormal blood vessels, which are hyperpermeable and immature, are often formed; these tissues also have irregular vascularisation and intravasation. This situation leads to hypoperfusion in tumour tissue along with low oxygen and nutrition depletion; this is also called the tumour microenvironment and is characterised by hypoxia, depleted nutrition, low pH and high interstitial pressure. This environment induces resistance to anticancer drugs, which causes an increase in anticancer drug doses, leading to increased side effects. We hypothesised that normalised tumour blood vessels would improve tumour tissue perfusion, resupply nutrition and re-oxygenate the tumour tissue. Chemotherapy would then be more effective and cause a decrease in anticancer drug doses. Here we report a neovascularisation-inducing drug that improved tumour vascular abnormalities, such as low blood flow, blood leakage and abnormal vessel structure. These results could lead to not only an increased chemo-sensitivity and tissue-drug distribution but also an up-regulated efficiency for cancer chemotherapy. This suggests that tumour blood vessel normalisation therapy accompanied by angiogenesis may be a novel strategy for cancer therapy.

Genome-wide gene expression profiling of tongue squamous cell carcinoma by RNA-seq

OBJECTIVE

Tongue squamous cell carcinoma (TSCC) is significantly more malignant than other type of oral squamous cell carcinoma (OSCC). In this study, we aimed to identify specific global gene expression signatures of TSCC to investigate the more invasive behavior of the deeply infiltrating cancer.

METHODS

Using RNA-seq technology, we detected gene expression of 20 TSCCs, 20 matched paratumor tissues, and 10 healthy normal mucosa tissues. Enrichment analysis of gene ontology (GO) and pathway was conducted using online tools DAVID for the dysregulated genes. Additionally, we performed the quantitative real-time RT-PCR (qRT-PCR) to validate the findings of RNA-Seq in 10 samples of TSCC, matched paratumor, and normal mucosa, respectively.

RESULTS

We detected 252 differentially expressed genes (DEGs) between TSCC and matched paratumor tissue, including 117 up-regulated and 135 down-regulated genes. For comparison between TSCC and normal mucosa, 234 DEGS were identified, consisting of 67 up-regulated and 167 down-regulated genes. For both two comparisons, GO categories of muscle contraction (GO: 0006936), epidermis development (GO: 0008544), epithelial cell differentiation (GO: 0030855), and keratinization (GO: 0031424) were commonly enriched. Altered gene expression affected some cancer-related pathways, such as tight junction. The qRT-PCR validation showed that gene expression patterns of FOLR1, NKX3-1, TFF3, PIGR, NEFL, MMP13, and HMGA2 were fully in concordance with RNA-Seq results.

CONCLUSION

Findings in this study demonstrated the genetic and molecular alterations associated with TSCC, providing new clues for understanding the molecular mechanisms of TSCC pathogenesis.

Expression of claudin 1, 4 and 7 in thyroid neoplasms

The distinction of thyroid carcinoma from benign thyroid neoplasm, as well as the subtyping of papillary carcinoma (PC) and follicular carcinoma (FC), may be performed histopathologically in the majority of cases. However, in certain cases, it is difficult to histopathologically distinguish between PC and FC, as well as follicular adenoma (FA), FC and the dominant nodule of multinodular goiter (MNG-DN). The present study aimed to determine the roles of the expression levels of the tight junction proteins claudin 1, 4 and 7 in the differential diagnosis of PC, FC, FA, MNG-DN, medullary carcinoma (MC) and anaplastic carcinoma (AC). The current study included 114 cases of histopathologically diagnosed thyroid neoplasia, which were distributed as follows: 29 FA, 18 MNG-DN, 47 PC, 10 FC, 5 MC and 5 AC. The expression levels of claudin 1, 4 and 7 were examined using immunohistochemical methods. The results revealed a significant difference in claudin 1 expression between malignant and benign thyroid neoplasms (P<0.001). Claudin 1 expression was not detected in any of the MNG-DN cases, and no significant difference in claudin 1 expression levels was identified between FA and FC (P=0.653). However, a statistically significant difference was observed between FC and PC (P<0.001). Claudin 4 expression did not differ between malignant and benign thyroid neoplasms, neither between MNG-DN, FA and FC, nor between FC and PC (P=0.068, P=0.502 and P=0.481, respectively). Claudin 7 exhibited positive immunohistochemical staining in 107 patients (94%); however, no significant difference in claudin 7 expression §levels was identified between malignant and benign thyroid neoplasms among MNG-DN, FA and FC (malignant, P=0.135; benign, P=0.470). Claudin 7 exhibited positive staining in all PC and FC cases. Therefore, claudin 1 expression levels may be useful in distinguishing cases of FC and PC with overlapping histopathological features, and provide a novel immunohistochemical marker for the subtyping of thyroid carcinoma.

Cell-surface markers for colon adenoma and adenocarcinoma

Early detection of colorectal cancer (CRC) is crucial for effective treatment. Among CRC screening techniques, optical colonoscopy is widely considered the gold standard. However, it is a costly and invasive procedure with a low rate of compliance. Our long-term goal is to develop molecular imaging agents for the non-invasive detection of CRC by molecular imaging-based colonoscopy using CT, MRI or fluorescence. To achieve this, cell surface targets must be identified and validated. Here, we report the discovery of cell-surface markers that distinguish CRC from surrounding tissues that could be used as molecular imaging targets. Profiling of mRNA expression microarray data from patient tissues including adenoma, adenocarcinoma, and normal gastrointestinal tissues was used to identify potential CRC specific cell-surface markers. Of the identified markers, six were selected for further validation (CLDN1, GPR56, GRM8, LY6G6D/F, SLCO1B3 and TLR4). Protein expression was confirmed by immunohistochemistry of patient tissues. Except for SLCO1B3, diffuse and low expression was observed for each marker in normal colon tissues. The three markers with the greatest protein overexpression were CLDN1, LY6G6D/F and TLR4, where at least one of these markers was overexpressed in 97% of the CRC samples. GPR56, LY6G6D/F and SLCO1B3 protein expression was significantly correlated with the proximal tumor location and with expression of mismatch repair genes. Marker expression was further validated in CRC cell lines. Hence, three cell-surface markers were discovered that distinguish CRC from surrounding normal tissues. These markers can be used to develop imaging or therapeutic agents targeted to the luminal surface of CRC.

Droplet-based microtumor model to assess cell-ECM interactions and drug resistance of gastric cancer cells

Gastric cancer (GC) is a common aggressive malignant tumor with high incidence and mortality worldwide. GC is classified into intestinal and diffuse types according to the histo-morphological features. Because of distinctly different clinico-pathological features, new cancer therapy strategies and in vitro preclinical models for the two pathological variants of GC is necessary. Since extracellular matrix (ECM) influence the biological behavior of tumor cells, we hypothesized that GC might be more similarly modeled in 3D with matrix rather than in 2D. Herein, we developed a microfluidic-based a three-dimensional (3D) in vitro gastric cancer model, with subsequent drug resistance assay. AGS (intestinal type) and Hs746T (diffuse type) gastric cancer cell lines were encapsulated in collagen beads with high cellular viability. AGS exhibited an aggregation pattern with expansive growth, whereas Hs746T showed single-cell-level infiltration. Importantly, in microtumor models, epithelial-mesenchymal transition (EMT) and metastatic genes were upregulated, whereas E-cadherin was downregulated. Expression of ß-catenin was decreased in drug-resistant cells, and chemosensitivity toward the anticancer drug (5-FU) was observed in microtumors. These results suggest that in vitro microtumor models may represent a biologically relevant platform for studying gastric cancer cell biology and tumorigenesis, and for accelerating the development of novel therapeutic targets.

Loss of tricellular tight junction protein LSR promotes cell invasion and migration via upregulation of TEAD1/AREG in human endometrial cancer

Lipolysis-stimulated lipoprotein receptor (LSR) is a unique molecule of tricellular contacts of normal and cancer cells. We investigated how the loss of LSR induced cell migration, invasion and proliferation in endometrial cancer cell line Sawano. mRNAs of amphiregulin (AREG) and TEA domain family member 1 (TEAD1) were markedly upregulated by siRNA-LSR. In endometrial cancer tissues, downregulation of LSR and upregulation of AREG were observed together with malignancy, and Yes-associated protein (YAP) was present in the nuclei. siRNA-AREG prevented the cell migration and invasion induced by siRNA-LSR, whereas treatment with AREG induced cell migration and invasion. LSR was colocalized with TRIC, angiomotin (AMOT), Merlin and phosphorylated YAP (pYAP). siRNA-LSR increased expression of pYAP and decreased that of AMOT and Merlin. siRNA-YAP prevented expression of the mRNAs of AREG and TEAD1, and the cell migration and invasion induced by siRNA-LSR. Treatment with dobutamine and 2-deoxy-D-glucose and glucose starvation induced the pYAP expression and prevented the cell migration and invasion induced by siRNA-LSR. siRNA-AMOT decreased the Merlin expression and prevented the cell migration and invasion induced by siRNA-LSR. The loss of LSR promoted cell invasion and migration via upregulation of TEAD1/AREG dependent on YAP/pYAP and AMOT/Merlin in human endometrial cancer cells.

Cancer metastasis: Mechanisms of inhibition by melatonin

Melatonin is a naturally occurring molecule secreted by the pineal gland and known as a gatekeeper of circadian clocks. Mounting evidence indicates that melatonin, employing multiple and interrelated mechanisms, exhibits a variety of oncostatic properties in a myriad of tumors during different stages of their progression. Tumor metastasis, which commonly occurs at the late stage, is responsible for the majority of cancer deaths; metastases lead to the development of secondary tumors distant from a primary site. In reference to melatonin, the vast majority of investigations have focused on tumor development and progression at the primary site. Recently, however, interest has shifted toward the role of melatonin on tumor metastases. In this review, we highlight current advances in understanding the molecular mechanisms by which melatonin counteracts tumor metastases, including experimental and clinical observations; emphasis is placed on the impact of both cancer and non-neoplastic cells within the tumor microenvironment. Due to the broad range of melatonin's actions, the mechanisms underlying its ability to interfere with metastases are numerous. These include modulation of cell-cell and cell-matrix interaction, extracellular matrix remodeling by matrix metalloproteinases, cytoskeleton reorganization, epithelial-mesenchymal transition, and angiogenesis. The evidence discussed herein will serve as a solid foundation for urging basic and clinical studies on the use of melatonin to understand and control metastatic diseases.

Detection and Enumeration of Circulating Tumor Cells with Invasive Phenotype

Circulating tumor cells (CTCs) disseminate from solid primary cancers into the peripheral blood and lymphatic vessels and can lead to metastatic tumor development; thus, CTC assays are an important clinical tool for monitoring progression and evaluating prognosis in cancer. However, CTCs are limited in number and heterogeneous in their biological and physical properties, making their detection, isolation, and enumeration a major challenge. To overcome these difficulties, novel techniques have been developed to detect and enumerate CTCs with an invasive phenotype. In this chapter, we will summarize these recently developed methods and detail two novel methods for capturing and enriching CTCs on the basis of their viability and their invasive properties.

Daxx inhibits hypoxia-induced lung cancer cell metastasis by suppressing the HIF-1α/HDAC1/Slug axis

Hypoxia is a major driving force of cancer invasion and metastasis. Here we show that death domain-associated protein (Daxx) acts to negatively regulate hypoxia-induced cell dissemination and invasion by inhibiting the HIF-1α/HDAC1/Slug pathway. Daxx directly binds to the DNA-binding domain of Slug, impeding histone deacetylase 1 (HDAC1) recruitment and antagonizing Slug E-box binding. This, in turn, stimulates E-cadherin and occludin expression and suppresses Slug-mediated epithelial–mesenchymal transition (EMT) and cell invasiveness. Under hypoxic conditions, stabilized hypoxia-inducible factor (HIF)-1α downregulates Daxx expression and promotes cancer invasion, whereas re-expression of Daxx represses hypoxia-induced cancer invasion. Daxx also suppresses Slug-mediated lung cancer metastasis in an orthotopic lung metastasis mouse model. Using clinical tumour samples, we confirmed that the HIF-1α/Daxx/Slug pathway is an outcome predictor. Our results support that Daxx can act as a repressor in controlling HIF-1α/HDAC1/Slug-mediated cancer cell invasion and is a potential therapeutic target for inhibition of cancer metastasis.

Hypoxia and epithelial-to-mesenchymal transition promotes cancer metastasis. Here the authors show that Daxx inhibits hypoxia-induced lung cancer metastasis by attenuating Slug-mediated transcriptional repression of epithelial-like markers that in turn cause cells to exhibit low invasiveness.

An emerging role for IQGAP1 in tight junction control

IQGAP1 is a scaffold protein involved in the assembly of adherens junctions. Our work has recently revealed a novel role for IQGAP1 in the regulation of tight junctions (TJ) through differential recruitment of claudins to the nascent TJ. Here, we discuss the potential mechanisms of this regulation, including IQGAP1 effects on CDC42, and IQGAP1 interactions with sorting/trafficking molecules (e.g. Exo70). Given the many roles of IQGAP1 and the large number of interacting partners, we focus our discussion of these functions in the context of junction formation, trafficking, growth factor signaling and cancer. We also propose a potential role for IQGAP1 in regulating epithelial integrity and compartmentalized signaling in epithelia.

Reacquisition of E-cadherin expression in metastatic deposits of signet-ring cell carcinoma of the upper gastrointestinal system: a potential anchor for metastatic deposition

AIMS

To examine the expression of E-cadherin in paired primary and metastatic signet-ring cell carcinomas (SRCC) of various organ systems in order to explore the potential role of the molecule in metastatic dissemination of this unique tumour type.

METHODS

Thirty-seven consecutive cases of SRCC from various organs with paired primary and metastatic tumorous tissue available were retrieved. The intensity of membranous E-cadherin expression was semiquantitatively scored on a scale of 0-3+.

RESULTS

Reduced E-cadherin expression was a distinct feature of primary SRCC and was observed in 78% of primary tumours. Interestingly, the E-cadherin reduction was less frequently seen in metastatic SRCC when compared with their primary counterparts, and was only found in 57% of tumours in lymph node metastases or at distant sites of relapse. Furthermore, the mean score of E-cadherin expression of primary SRCC was significantly lower than that of their metastatic counterparts (2.3 vs 1.8; p=0.008). When divided by organ systems, the reacquisition of E-cadherin expression in the metastatic deposits was most remarkable in the SRCC of upper gastrointestinal tract origin (2.3 vs 1.4; p=0.003), whereas no significant difference was observed in other organ systems.

CONCLUSIONS

While the reduction of E-cadherin in primary SRCC supports its pivotal role in epithelial-mesenchymal transition, a process crucial in tumour progression and metastatic dissemination, the re-expression of this molecule in metastatic SRCC cells implies a reversal to their epithelial phenotype (thus mesenchymal-epithelial transition) which, in turn, theoretically helps tumour cells to anchor and form cohesive metastatic deposits.

A three-dimensional spheroidal cancer model based on PEG-fibrinogen hydrogel microspheres

Three-dimensional (3D) in vitro cancer models offer an attractive approach towards the investigation of tumorigenic phenomena and other cancer studies by providing dimensional context and higher degree of physiological relevance than that offered by conventional two-dimensional (2D) models. The multicellular tumor spheroid model, formed by cell aggregation, is considered to be the "gold standard" for 3D cancer models, due to its ease and simplicity of use. Although better than 2D models, tumor spheroids are unable to replicate key features of the native tumor microenvironment, particularly due to a lack of surrounding extracellular matrix components and heterogeneity in shape, size and aggregate forming tendencies. In order to address this issue, we have developed a 3D "tumor microsphere" model, formed by a dual-photoinitiator, aqueous-oil emulsion technique, for the encapsulation of cancer cells within PEG-fibrinogen hydrogel microspheres and for subsequent long-term 3D culture. In comparison to self-aggregated tumor spheroids, the tumor microspheres displayed a higher degree of size and shape homogeneity throughout long-term culture. In sharp contrast to cells in tumor spheroids, cells within tumor microspheres demonstrated significant loss in apico-basal polarity and cellular architecture, cellular and nuclear atypia, increased disorganization, elevated nuclear cytoplasmic ratio and nuclear volume density and reduction in cell-cell junction length, all of which are hallmarks of malignant transformation and tumorigenic progression. Additionally, the tumor microsphere model was extended for the 3D encapsulation and maintenance of a wide range of other cancer cell (metastatic and non-metastatic) types. Taken together, our results reinforce the importance of incorporating a biomimetic matrix in the cellular microenvironment of 3D tumor models and the influential effects of the matrix on the tumorigenic morphology of 3D cultured cells. The tumor microsphere system established in this study has the potential to be used in future investigations of 3D cancer cell-cell and cell-ECM interactions and in drug-testing applications.

Claudin-4 activity in ovarian tumor cell apoptosis resistance and migration

Background

Claudin-4 is a transmembrane protein expressed at high levels in the majority of epithelial ovarian tumors, irrespective of subtype, and has been associated with tumor cells that are both chemoresistant and highly mobile. The objective of this study was to determine the functional role that claudin-4 plays in apoptosis resistance and migration as well as the therapeutic utility of targeting claudin-4 activity with a small mimic peptide.

Methods

We examined claudin-4 activity in human ovarian tumor cell lines (SKOV3, OVCAR3, PEO4) using in vitro caspase and scratch assays as well as an in vivo mouse model of ovarian cancer. Claudin-4 activity was disrupted by treating cells with a small peptide that mimics the DFYNP sequence in the second extracellular loop of claudin-4. Claudin-4 expression was also altered using shRNA-mediated gene silencing.

Results

Both the disruption of claudin-4 activity and the loss of claudin-4 expression significantly increased tumor cell caspase-3 activation (4 to 10-fold, respectively) in response to the apoptotic inducer staurosporine and reduced tumor cell migration by 50 %. The mimic peptide had no effect on cells that lacked claudin-4 expression. Female athymic nude mice bearing ZsGreen-PEO4 ovarian tumors showed a significant decrease in ovarian tumor burden, due to increased apoptosis, after treatment with intraperitoneal injections of 4 mg/kg mimic peptide every 48 h for three weeks, compared to control peptide treated mice.

Conclusion

Claudin-4 functionally contributes to both ovarian tumor cell apoptosis resistance and migration and targeting extracellular loop interactions of claudin-4 may have therapeutic implications for reducing ovarian tumor burden.

Crumbs 3b promotes tight junctions in an ezrin-dependent manner in mammalian cells

Crumbs 3 (CRB3) is a component of epithelial junctions, which has been implicated in apical-basal polarity, apical identity, apical stability, cell adhesion, and cell growth. CRB3 undergoes alternative splicing to yield two variants: CRB3a and CRB3b. Here, we describe novel data demonstrating that, as with previous studies on CRB3a, CRB3b also promotes the formation of tight junctions (TJs). However, significantly we demonstrate that the 4.1-ezrin-radixin-moesin-binding motif of CRB3b is required for CRB3b functionality and that ezrin binds to the FBM of CRB3b. Furthermore, we show that ezrin contributes to CRB3b functionality and the correct distribution of TJ proteins. We demonstrate that both CRB3 isoforms are required for the production of functionally mature TJs and also the localization of ezrin to the plasma membrane. Finally, we demonstrate that reduced CRB3b expression in head and neck squamous cell carcinoma (HNSCC) correlates with cytoplasmic ezrin, a biomarker for aggressive disease, and shows evidence that while CRB3a expression has no effect, low CRB3b and high cytoplasmic ezrin expression combined may be prognostic for HNSCC.

Cancer Cell Colonisation in the Bone Microenvironment

Bone metastases are a common complication of epithelial cancers, of which breast, prostate and lung carcinomas are the most common. The establishment of cancer cells to distant sites such as the bone microenvironment requires multiple steps. Tumour cells can acquire properties to allow epithelial-to-mesenchymal transition, extravasation and migration. Within the bone metastatic niche, disseminated tumour cells may enter a dormancy stage or proliferate to adapt and survive, interacting with bone cells such as hematopoietic stem cells, osteoblasts and osteoclasts. Cross-talk with the bone may alter tumour cell properties and, conversely, tumour cells may also acquire characteristics of the surrounding microenvironment, in a process known as osteomimicry. Alternatively, these cells may also express osteomimetic genes that allow cell survival or favour seeding to the bone marrow. The seeding of tumour cells in the bone disrupts bone-forming and bone-resorbing activities, which can lead to macrometastasis in bone. At present, bone macrometastases are incurable with only palliative treatment available. A better understanding of how these processes influence the early onset of bone metastasis may give insight into potential therapies. This review will focus on the early steps of bone colonisation, once disseminated tumour cells enter the bone marrow.

Longitudinal Claudin Gene Expression Analyses in Canine Mammary Tissues and Thereof Derived Primary Cultures and Cell Lines

Human and canine mammary tumours show partial claudin expression deregulations. Further, claudins have been used for directed therapeutic approaches. However, the development of claudin targeting approaches requires stable claudin expressing cell lines. This study reports the establishment and characterisation of canine mammary tissue derived cell lines, analysing longitudinally the claudin-1, -3, -4 and -7 expressions in original tissue samples, primary cultures and developed cell lines. Primary cultures were derived from 17 canine mammary tissues: healthy, lobular hyperplasia, simple adenoma, complex adenoma, simple tubular carcinoma, complex carcinoma, carcinoma arising in a benign mixed tumour and benign mixed tissue. Cultivation was performed, if possible, until passage 30. Claudin mRNA and protein expressions were analysed by PCR, QuantiGene Plex Assay, immunocytochemistry and immunofluorescence. Further, cytokeratin expression was analysed immunocytochemically. Cultivation resulted in 11 established cell lines, eight showing epithelial character. In five of the early passages the claudin expressions decreased compared to the original tissues. In general, claudin expressions were diminished during cultivation. Three cell lines kept longitudinally claudin, as well as epithelial marker expressions, representing valuable tools for the development of claudin targeted anti-tumour therapies.

Reversed cellular polarity in primary cutaneous mucinous carcinoma: A study on tight junction protein expression in sweat gland tumors

Primary cutaneous mucinous carcinoma (PCMC) is a rare sweat gland tumor characterized by the presence of abundant mucin around the tumor islands, but the molecular mechanisms for this structure are not well elucidated. Because mucin is epithelial in nature, it is likely to be produced by epithelial tumor cells, not by surrounding stromal cells. We hypothesized that the abundant mucin is a result of reversed cellular polarity of the tumor. To test this hypothesis, we conducted an immunohistological study to investigate expression of tight junction (TJ) proteins occludin and ZO-1 in PCMC, as well as in normal sweat glands and other sweat gland tumors. Dot-like or linear expression of TJ proteins was observed at ductal structures of sweat glands, and ductal or cystic structures of related tumors. In PCMC, however, TJ protein expression was clearly visible at the edges of tumor cell islands. This study provides evidence to show that the characteristic histological structure of PCMC is caused by inverse polarization of the tumor cells, and that TJ proteins are useful markers of ductal differentiation in sweat gland tumors.

Role of TGF-β-induced Claudin-4 expression through c-Jun signaling in non-small cell lung cancer

Claudin-4 has been identified as an integral member of tight junctions and has been found to be upregulated in various types of cancers especially in metastatic cancers. However, the molecular mechanism of the upregulation of Claudin-4 and its role in lung tumorigenesis are unknown. The aim of the present study is to investigate the role of Claudin-4 on migration and tumorigenicity of lung cancer cells and to examine the regulatory effects of TGF-β on Claudin-4 expression. We have observed that TGF-β induces the expression of Claudin-4 dramatically in lung cell lines in a time dependent manner. TGF-β-induced Smad signaling is important for enhancing Claudin-4 mRNA level through inducing its promoter activity. Treatment with curcumin, a c-Jun inhibitor, or stable knockdown of c-Jun abrogates TGF-β-induced Claudin-4 expression suggesting an involvement of the c-Jun pathway. Notably, TGF-β-induced Claudin-4 expression through c-Jun pathway plays a role in TGF-β-mediated motility and tumorigenicity of these cells. In support of these observations, we have uncovered that Claudin-4 is upregulated in 14 of 24 (58%) lung tumors when compared with normal lung tissue. This is the first study to show how TGF-β regulates the expression of Claudin-4 through c-Jun signaling and how this pathway contributes to the migratory and tumorigenic phenotype of lung tumor cells.

The role of JAM-B in cancer and cancer metastasis (Review)

The junctional adhesion molecule B (JAM-B) is a multifunctional transmembrane protein, which belongs to the immunoglobulin superfamily (IgSF). JAM-B is localized to cell-cell contacts and enriched at cell junctions in epithelial and endothelial cells, as well as on the surface of erythrocytes, leukocytes, and platelets. Recent research in this field has shown that JAM-B plays an important role in numerous cellular processes, such as tight junction assembly, spermatogenesis, regulation of paracellular permeability, leukocytic transmigration, angiogenesis, tumor metastasis and cell proliferation. This study provides a new research direction for the diagnosis and treatment of relevant diseases. In this review, we briefly focus on what is currently known about the structure, function, and mechanism of JAM-B, with particular emphasis on cancer.

CHST11/13 Regulate the Metastasis and Chemosensitivity of Human Hepatocellular Carcinoma Cells Via Mitogen-Activated Protein Kinase Pathway

BACKGROUND

Carbohydrate sulfotransferases 11-13 (CHST11-13), that catalyze the transfer of sulfate to position 4 of the GalNAc residue of chondroitin, have been implicated in various diseases.

AIM

This study aimed to clarify the association of CHST11-13 expression with metastasis and drug sensitivity in hepatocellular carcinoma (HCC) cells.

METHODS

We measured the levels of CHST11 and CHST13 in a series of HCC cells using real-time PCR and Western blotting. After RNAi and forced expression treatment of CHST11 and CHST13 in MHCC97L and MHCC97H cells, metastatic potential and drug sensitivity of the two cells were investigated with ECM invasion assay, drug sensitivity assay, and in vivo antitumor activity assay. By real-time PCR and Western blotting, we explored the possible impacts of these two genes on mitogen-activated protein kinase (MAPK) signal pathway. MAPK pathway was blocked by PD98059 or SP600125 to elucidate the effects of MAPK pathway on metastasis and chemosensitivity.

RESULTS

Significantly reduced levels of CHST11 and CHST13 were observed in highly invasive MHCC97H cells compared with those of MHCC97L cell line with low metastatic potential. Decreased or forced expression of CHST11 and CHST13 altered metastatic potential and drug sensitivity of MHCC97L and MHCC97H cells. Remarkable alteration of MAPK activity was shown in two HCC cells with genetic manipulation. Conversely, pharmacologic inhibition of the MAPK pathway suppressed invasive potential and rescued drug sensitivity of MHCC97H cells.

CONCLUSIONS

Our results have demonstrated that CHST11 and CHST13 negatively modulate metastasis and drug resistance of HCC cells probably via oncogenic MAPK signal pathway.

Tight Junctions and the Tumor Microenvironment

PURPOSE OF REVIEW

Tight junctions (TJs) are specialized differentiations of epithelial and endothelial cell membranes. TJs play an important role in the adhesion of cells and their interaction with each other. Most cancers originate from epithelial cells. Thus, it is of significance to examine the role of TJs in the tumor microenvironment (TME) and how they affect cancer metastasis.

RECENT FINDINGS

In epithelium-derived cancers, intactness of the primary tumor mass is influenced by intercellular structures as well as cell-to-cell adhesion. Irregularities of these factors may lead to tumor dissociation and subsequent metastasis. Low expression of TJs is observed among highly metastatic cancer cells.

SUMMARY

In this review, we summarized findings from current literature in consideration of the role of TJs in relation to the TME and cancer. Deeper understanding of the mechanisms leading to TJ dysregulation is needed to facilitate the design and conceptualization of new and better therapeutic strategies for cancer.

High-fat diets rich in saturated fat protect against azoxymethane/dextran sulfate sodium-induced colon cancer

High-fat-diet (HFD) consumption is associated with colon cancer risk. However, little is known about how the lipid composition of a HFD can influence prooncogenic processes. We examined the effects of three HFDs differing in the percentage of total calories from saturated fat (SF) (6, 12, and 24% of total caloric intake), but identical in total fat (40%), and a commercially available Western diet (26 and 41% saturated and total fat, respectively) on colon cancer development using the azoxymethane (AOM)/dextran sulfate sodium (DSS) murine model. A second dose-response experiment was performed using diets supplemented with the saturated-fatty-acid (SFA)-rich coconut oil. In experiment 1, we found an inverse association between SF content and tumor burden. Furthermore, increased SF content was associated with reduced inflammation, increased apoptosis, and decreased proliferation. The second dose-response experiment was performed to test whether this effect may be attributed to the SF content of the diets. Consistent with the initial experiment, we found that high SF content was protective, at least in male mice; there was a decrease in mortality in mice consuming the highest concentration of SFAs. To explore a potential mechanism for these findings, we examined colonic mucin 2 (Muc2) protein content and found that the HFDs with the highest SF content had the greatest concentration of Muc2. Our data suggest that high dietary SF is protective in the AOM/DSS model of colon cancer, which may be due, at least in part, to the ability of SF to maintain intestinal barrier integrity through increased colonic Muc2.

Effects of Panax notoginseng on the Metastasis of Human Colorectal Cancer Cells

The goal of this study was to investigate the effect of the Panax notoginseng ethanol extract (PNEE) on the regulation of human colorectal cancer (CRC) metastasis. The migratory, invasive, and adhesive abilities and the expression of metastasis-associated regulatory molecules in cultured human CRC cells (HCT-116) treated with the PNEE were analyzed in this study. The migratory and invasive abilities of HCT-116 cells were reduced after PNEE treatment. The incubation of HCT-116 cells with the PNEE for 24 h decreased MMP-9 expression and increased E-cadherin expression compared with the control group. The adhesion reaction assay indicated that treatment with the PNEE led to significantly decreased HCT-116 adhesion to endothelial cells (EA.hy926 cells). The integrin-1 protein levels in HCT-116 cells were significantly decreased following treatment with the PNEE. Similarly, the protein levels of E-selectin and intercellular adhesion molecule-1 (ICAM-1) were significantly decreased by treatment of the EA.hy926 endothelial cells with PNEE. A scanning electron microscope (SEM) examination indicated that HCT-116 cells treated with LPS combined with the PNEE had a less flattened and retracted shape compared with LPS-treated cells, and this change in shape was found to be a phenomenon of extravasation invasion. The transepithelial electrical resistance (TEER) of the EA.hy926 endothelial cell monolayer increased after incubation with the PNEE for 24 h. A cell-cell permeability assay indicated that HCT-116 cells treated with the PNEE displayed significantly reduced levels of phosphorylated VE-cadherin (p-VE-cadherin). These results demonstrate the antimetastatic properties of the PNEE and show that the PNEE affects cells by inhibiting cell migration, invasion, and adhesion and regulating the expression of metastasis-associated signaling molecules.

Gene-set activity toolbox (GAT): A platform for microarray-based cancer diagnosis using an integrative gene-set analysis approach

Cancer is a complex disease that cannot be diagnosed reliably using only single gene expression analysis. Using gene-set analysis on high throughput gene expression profiling controlled by various environmental factors is a commonly adopted technique used by the cancer research community. This work develops a comprehensive gene expression analysis tool (gene-set activity toolbox: (GAT)) that is implemented with data retriever, traditional data pre-processing, several gene-set analysis methods, network visualization and data mining tools. The gene-set analysis methods are used to identify subsets of phenotype-relevant genes that will be used to build a classification model. To evaluate GAT performance, we performed a cross-dataset validation study on three common cancers namely colorectal, breast and lung cancers. The results show that GAT can be used to build a reasonable disease diagnostic model and the predicted markers have biological relevance. GAT can be accessed from http://gat.sit.kmutt.ac.th where GAT's java library for gene-set analysis, simple classification and a database with three cancer benchmark datasets can be downloaded.

Calcitonin Receptor-Zonula Occludens-1 Interaction Is Critical for Calcitonin-Stimulated Prostate Cancer Metastasis

The role of neuroendocrine peptide calcitonin (CT) and its receptor (CTR) in epithelial cancer progression is an emerging concept with great clinical potential. Expression of CT and CTR is frequently elevated in prostate cancers (PCs) and activation of CT–CTR axis in non-invasive PC cells induces an invasive phenotype. Here we show by yeast-two hybrid screens that CTR associates with the tight junction protein Zonula Occludens-1 (ZO-1) via the interaction between the type 1 PDZ motif at the carboxy-terminus of CTR and the PDZ3 domain of ZO-1. Mutation of either the CTR C-PDZ-binding motif or the ZO-1-PDZ3 domain did not affect binding of CTR with its ligand or G-protein-mediated signaling but abrogated destabilizing actions of CT on tight junctions and formation of distant metastases by orthotopically implanted PC cells in nude mice, indicating that these PDZ domain interactions were pathologically relevant. Further, we observed CTR-ZO-1 interactions in PC specimens by proximity ligation immunohistochemistry, and identified that the number of interactions in metastatic PC specimens was several-fold larger than in non-metastatic PC. Our results for the first time demonstrate a mechanism by which PDZ-mediated interaction between CTR and ZO1 is required for CT-stimulated metastasis of prostate cancer. Since many receptors contain PDZ-binding motifs, this would suggest that PDZ-binding motif-adaptor protein interactions constitute a common mechanism for cancer metastasis.

The influence of the WWOX gene on the regulation of biological processes during endometrial carcinogenesis

The purpose of the present study was to investigate the role of WW domain containing oxidoreductase (WWOX) downregulation in biological cancer-related processes in normal (non-malignant) and cancer endometrial cell lines. We created an in vitro model using the normal endometrial cell line, THESC, and 2 endometrial cancer cell lines with varying degrees of differentiation, the Ishikawa (well-differentiated) and the MFE296 (moderately differentiated) cells, in which the WWOX tumor suppressor gene was silenced using Gipz lentiviral shRNA. In this model, we examined the changes in invasiveness via biological assays, such as zymography, migration through a basement membrane, the adhesion of cells to extracellular matrix proteins, anchorage-independent growth and colony formation assay. We also evaluated the correlation between the mRNA expression of the WWOX gene and genes involved in the processes of carcinogenesis, namely catenin beta-1 (CTNNB1) and zinc finger E-box binding homeobox 1 (ZEB1) (gene transcription), cadherin 1 (CDH1) and ezrin (EZR) (cell adhesion), vimentin (VIM) (structural proteins), as well as phosphatase and tensin homolog (PTEN) (tumor suppression) and secreted protein, acidic, cysteine-rich (osteonectin) (SPARC) (SPARC) (cell growth regulation) by RT-qPCR. Downregulation of the WWOX gene in the moderately differentiated MFE296 cell line caused decreased migratory capacity, and a reduction of matrix metalloproteinase-2 (MMP-2) activity. However, these cells grew in semisolid medium and exhibited higher expression of CDH1 and EZR (cell adhesion) and secreted protein, acidic, cysteine-rich (osteonectin) (SPARC) (cell growth regulation). Moreover, in the well-differentiated endometrial cancer (Ishikawa) cell line, WWOX gene silencing resulted in an increased ability of the cells to proliferate indefinitely. Additionally, WWOX regulated changes in adhesion potential in both the normal and cancer cell lines. Our results suggest that the WWOX tumor suppressor gene modulated the processes of cell motility, cell adhesion, gene expression and remodeling in endometrial cell lines.

Targeting the Epithelial-to-Mesenchymal Transition: The Case for Differentiation-Based Therapy

Although important strides have been made in targeted therapy for certain leukemias and subtypes of breast cancer, the standard of care for most carcinomas still involves chemotherapy, radiotherapy, surgery, or a combination of these. Two processes serve as obstacles to the successful treatment of carcinomas. First, a majority of deaths from these types of cancers occurs as a result of distant metastases and not the primary tumors themselves. Second, subsets of cells that are able to survive conventional therapy drive the aggressive relapse of the tumors, often in forms that are resistant to treatment. A frequently observed feature of malignant carcinomas is the loss of epithelial traits and the gain of certain mesenchymal ones that are programmed by the cell-biological program termed the epithelial-to-mesenchymal transition (EMT). The EMT program can confer (i) an ability to disseminate, (ii) an ability to become stem-like tumor-initiating cells, (iii) an ability to found new tumor colonies at distant anatomical sites, and (iv) an elevated resistance to therapy. These multiple powers of the EMT program explain why it has become an attractive target for therapeutic intervention. Recent work has revealed the variable nature of the EMT, with multiple versions of the program being observed depending on the tissue context and the stage of tumor progression. In this review, we attempt to crystallize emerging concepts in the research on EMT and stemness and discuss the benefits of using a differentiation-based therapeutic strategy for the eradication of stem-like populations that have adopted various versions of the EMT program.

Abnormal Barrier Function in Gastrointestinal Disorders

There is increasing concern in identifying the mechanisms underlying the intimate control of the intestinal barrier, as deregulation of its function is strongly associated with digestive (organic and functional) and a number of non-digestive (schizophrenia, diabetes, sepsis, among others) disorders. The intestinal barrier is a complex and effective defensive functional system that operates to limit luminal antigen access to the internal milieu while maintaining nutrient and electrolyte absorption. Intestinal permeability to substances is mainly determined by the physicochemical properties of the barrier, with the epithelium, mucosal immunity, and neural activity playing a major role. In functional gastrointestinal disorders (FGIDs), the absence of structural or biochemical abnormalities that explain chronic symptoms is probably close to its end, as recent research is providing evidence of structural gut alterations, at least in certain subsets, mainly in functional dyspepsia (FD) and irritable bowel syndrome (IBS). These alterations are associated with increased permeability, which seems to reflect mucosal inflammation and neural activation. The participation of each anatomical and functional component of barrier function in homeostasis and intestinal dysfunction is described, with a special focus on FGIDs.

Crucial Role of FLVCR1a in the Maintenance of Intestinal Heme Homeostasis

AIMS

The maintenance of heme homeostasis, mucosa cell renewal, and redox environment in the intestine is essential to permit digestion, absorption, cell proliferation, cell apoptosis, and immune response and to avoid the development of gut disorders. The feline leukemia virus, subgroup C, receptor 1a (FLVCR1a) is a heme exporter expressed in almost all cell types, including intestinal cells. This work investigates the role of FLVCR1a in the intestine, taking advantage of an intestine-specific conditional Flvcr1a-knockout mouse and of FLVCR1a-depleted Caco2 cells.

RESULTS

The data show that FLVCR1a does not participate in the absorption of dietary heme, whereas it is involved in the export of de novo synthesized heme from intestinal cells. The loss of Flvcr1a is associated with a decrease of intestinal cell proliferation and with alterations in the peculiar homeostasis of proliferating cells, including the maintenance of their redox status. The involvement of FLVCR1a in these processes renders this exporter crucial for the survival of mice in a model of ulcerative colitis.

INNOVATION

These findings shed light on the role of heme export in the dietary heme absorption process and unravel a new role for heme export in the control of mucosal renewal and in proliferating cell redox status and metabolic activity, demonstrating a crucial role for FLVCR1a in maintaining intestinal homeostasis in both physiologic and pathologic situations.

CONCLUSION

By exporting the excess of de novo synthesized heme from intestinal cells, FLVCR1a participates in the control of intestinal mucosa homeostasis.

Methionine restriction fundamentally supports health by tightening epithelial barriers

Dietary methionine restriction (MR) has been found to affect one of the most primary tissue-level functions of an organism: the efficiency with which the epithelial linings of major organs separate the fluid compartments that they border. This process, epithelial barrier function, is basic for proper function of all organs, including the lung, liver, gastrointestinal tract, reproductive tract, blood-brain barrier, and kidney. Specifically, MR has been found to modify the protein composition of tight junctional complexes surrounding individual epithelial cells in a manner that renders the complexes less leaky. This has been observed in both a renal epithelial cell culture model and in gastrointestinal tissue. In both cases, MR increased the transepithelial electrical resistance across the epithelium, while decreasing passive leak of small nonelectrolytes. However, the specific target protein modifications involved were unique to each case. Overall, this provides an example of the primary level on which MR functions to modify, and improve, an organism.