Epithelial and mesenchymal phenotypic switchings modulate cell motility in metastasis

FGFR2 in the Development and Progression of Cutaneous Squamous Cell Cancer

Cutaneous squamous cell carcinoma (cSCC) is an increasingly common malignancy of the skin and the leading cause of death from skin cancer in adults over the age of 85. Fibroblast growth factor receptor 2 (FGFR2) has been identified as an important effector of signaling pathways that lead to the growth and development of cSCC. In recent years, there have been numerous studies evaluating the role FGFR2 plays in multiple cancers, its contribution to resistance to anticancer therapy, and new drugs that may be used to inhibit FGFR2. This review will provide an overview of our current understanding of FGFR2 and potential mechanisms in which we can target FGFR2 in cSCC. The goals of this review are the following: (1) to highlight our current knowledge of the role of FGFR2 in healthy skin and contrast this with its role in the development of cancer; (2) to further explain the specific molecular mechanisms that FGFR2 uses to promote tumorigenesis; (3) to describe how FGFR2 contributes to more invasive disease; (4) to describe its immunosuppressive effects in skin; and (5) to evaluate its effect on current anticancer therapy and discuss therapies on the horizon to target FGFR2 related malignancy.

The dual effect of fiber density and matrix stiffness on A549 tumor multicellular migration

The tumor microenvironment features dynamic biomechanical interactions between extracellular matrix physics and tumor progression. Tumor growth compresses the supportive matrix, and the stiffness-gradient guides tumor invasion. From the mechanical perspective, the complexity of the matrix topology involving durotaxis-driven metastasis remains lacking in a comprehensive description. In this study, A549 adenocarcinoma spheroids were exposed to a stiffness-and fiber-adjusted collagen matrix to examine the influence of collective motility. Centrifugated compression on the collagen constructs was adopted to mimic the matrix deformation in response to solid tumor development. Centrifugated compression physically stiffened and condensed collagen constructs simultaneously. Cultured with A549 spheroids for 7 days, compressed collagen constructs disadvantaged spheroid expansion without the effect of tumor proliferation potency but promoted matrix metalloproteinase activity corresponding to softened rigidity. Results suggested that the fibrous structure may counterbalance the matrix stiffness-induced motility.

A high-throughput microfabricated platform for rapid quantification of metastatic potential

Assays that measure morphology, proliferation, motility, deformability, and migration are used to study the invasiveness of cancer cells. However, native invasive potential of cells may be hidden from these contextual metrics because they depend on culture conditions. We created a micropatterned chip that mimics the native environmental conditions, quantifies the invasive potential of tumor cells, and improves our understanding of the malignancy signatures. Unlike conventional assays, which rely on indirect measurements of metastatic potential, our method uses three-dimensional microchannels to measure the basal native invasiveness without chemoattractants or microfluidics. No change in cell death or proliferation is observed on our chips. Using six cancer cell lines, we show that our system is more sensitive than other motility-based assays, measures of nuclear deformability, or cell morphometrics. In addition to quantifying metastatic potential, our platform can distinguish between motility and invasiveness, help study molecular mechanisms of invasion, and screen for targeted therapeutics.

Mesenchymal Stem Cell-Secreted Exosomes and Soluble Signals Regulate Breast Cancer Metastatic Dormancy: Current Progress and Future Outlook

Breast cancer is most common in women, and in most cases there is no evidence of spread and the primary tumor is removed, resulting in a 'cure'. However, in 10% to 30% of these women, distant metastases recur after years to decades. This is due to breast cancer cells disseminating to distant organs and lying quiescent. This is called metastatic dormancy. Dormant cells are generally resistant to chemotherapy, hormone therapy and immunotherapy as they are non-cycling and receive survival signals from their microenvironment. In this state, they are clinically irrelevant. However, risk factors, including aging and inflammation can awaken dormant cells and cause breast cancer recurrences, which may happen even more than ten years after the primary tumor removal. How these breast cancer cells remain in dormancy is being unraveled. A key element appears to be the mesenchymal stem cells in the bone marrow that have been shown to promote breast cancer metastatic dormancy in recent studies. Indirect co-culture, direct co-culture and exosome extraction were conducted to investigate the modes of signal operation. Multiple signaling molecules act in this process including both protein factors and microRNAs. We integrate these studies to summarize current findings and gaps in the field and suggest future research directions for this field.

A paclitaxel-hyaluronan conjugate (ONCOFID-P-B™) in patients with BCG-unresponsive carcinoma in situ of the bladder: a dynamic assessment of the tumor microenvironment

BACKGROUND

The intravesical instillation of the paclitaxel-hyaluronan conjugate ONCOFID-P-B™ in patients with bacillus Calmette-Guérin (BCG)-unresponsive bladder carcinoma in situ (CIS; NCT04798703 phase I study), induced 75 and 40% of complete response (CR) after 12 weeks of intensive phase and 12 months of maintenance phase, respectively. The aim of this study was to provide a detailed description of the tumor microenvironment (TME) of ONCOFID-P-B™-treated BCG-unresponsive bladder CIS patients enrolled in the NCT04798703 phase I study, in order to identify predictive biomarkers of response.

METHODS

The composition and spatial interactions of tumor-infiltrating immune cells and the expression of the most relevant hyaluronic acid (HA) receptors on cancer cells, were analyzed in biopsies from the 20 patients enrolled in the NCT04798703 phase I study collected before starting ONCOFID-P-B™ therapy (baseline), and after the intensive and the maintenance phases. Clinical data were correlated with cell densities, cell distribution and cell interactions. Associations between immune populations or HA receptors expression and outcome were analyzed using univariate Cox regression and log-rank analysis.

RESULTS

In baseline biopsies, patients achieving CR after the intensive phase had a lower density of intra-tumoral CD8+ cytotoxic T lymphocytes (CTL), but also fewer interactions between CTL and macrophages or T-regulatory cells, as compared to non-responders (NR). NR expressed higher levels of the HA receptors CD44v6, ICAM-1 and RHAMM. The intra-tumoral macrophage density was positively correlated with the expression of the pro-metastatic and aggressive variant CD44v6, and the combined score of intra-tumoral macrophage density and CD44v6 expression had an AUC of 0.85 (95% CI 0.68-1.00) for patient response prediction.

CONCLUSIONS

The clinical response to ONCOFID-P-B™ in bladder CIS likely relies on several components of the TME, and the combined evaluation of intra-tumoral macrophages density and CD44v6 expression is a potentially new predictive biomarker for patient response. Overall, our data allow to advance a potential rationale for combinatorial treatments targeting the immune infiltrate such as immune checkpoint inhibitors, to make bladder CIS more responsive to ONCOFID-P-B™ treatment.

Modulation of E-Cadherin Function through the AmotL2 Isoforms Promotes Ameboid Cell Invasion

The spread of tumor cells and the formation of distant metastasis remain the main causes of mortality in cancer patients. However, the mechanisms governing the release of cells from micro-environmental constraints remain unclear. E-cadherin negatively controls the invasion of epithelial cells by maintaining cell-cell contacts. Furthermore, the inactivation of E-cadherin triggers invasion in vitro. However, the role of E-cadherin is complex, as metastasizing cells maintain E-cadherin expression, which appears to have a positive role in the survival of tumor cells. In this report, we present a novel mechanism delineating how E-cadherin function is modulated to promote invasion. We have previously shown that E-cadherin is associated with p100AmotL2, which is required for radial actin formation and the transmission of mechanical force. Here, we present evidence that p60AmotL2, which is expressed in invading tumor cells, binds to the p100AmotL2 isoform and uncouples the mechanical constraint of radial actin filaments. We show for the first time that the coupling of E-cadherin to the actin cytoskeleton via p100AmotL2 is directly connected to the nuclear membrane. The expression of p60AmotL2 inactivates this connection and alters the properties of the nuclear lamina, potentiating the invasion of cells into micropores of the extracellular matrix. In summary, we propose that the balance of the two AmotL2 isoforms is important in the modulation of E-cadherin function and that an imbalance of this axis promotes ameboid cell invasion.

Generation of Stable Epithelial-Mesenchymal Hybrid Cancer Cells with Tumorigenic Potential

PURPOSE

Cancer progression, invasiveness, and metastatic potential have been associated with the activation of the cellular development program known as epithelial-to-mesenchymal transition (EMT). This process is known to yield not only mesenchymal cells, but instead an array of cells with different degrees of epithelial and mesenchymal phenotypes with high plasticity, usually referred to as E/M hybrid cells. The characteristics of E/M hybrid cells, their importance in tumor progression, and the key regulators in the tumor microenvironment that support this phenotype are still poorly understood.

METHODS

In this study, we established an in vitro model of EMT and characterized the different stages of differentiation, allowing us to identify the main genomic signature associated with the E/M hybrid state.

RESULTS

We report that once the cells enter the E/M hybrid state, they acquire stable anoikis resistance, invasive capacity, and tumorigenic potential. We identified the hepatocyte growth factor (HGF)/c-MET pathway as a major driver that pushes cells in the E/M hybrid state.

CONCLUSIONS

Herein, we provide a detailed characterization of the signaling pathway(s) promoting and the genes associated with the E/M hybrid state.

Gastric cancer multicellular spheroid analysis by two-photon microscopy

Gastric cancer (GC) is highly deadly. Three-dimensional (3D) cancer cell cultures, known as spheroids, better mimic tumor microenvironment (TME) than standard 2D cultures. Cancer-associated fibroblasts (CAF), a major cellular component of TME, promote or restrain cancer cell proliferation, invasion and resistance to drugs. We established spheroids from two human GC cell lines mixed with human primary CAF. Spheroid organization, analyzed by two-photon microscopy, showed CAF in AGS/CAF spheroids clustered in the center, but dispersed throughout in HGT-1/CAF spheroids. Such differences may reflect clonal specificities of GC cell lines and point to the fact that GC should be considered as a highly personalized disease.

Akt isoforms differentially provide for chemoresistance in prostate cancer

OBJECTIVE

Early prostate cancer micrometastatic foci undergo a mesenchymal to epithelial reverting transition, not only aiding seeding and colonization, but also rendering the tumor cells generally chemoresistant. We previously found that upregulated E-cadherin in the epithelial micrometastases activated canonical survival pathways, including PI3K-Akt, that protected the tumor cells from death; however, the extent of protection from blocking the pathway in its entirety was modest, because different isoforms may have alternately affected cell functioning. Here, we characterized Akt isoform expressions in primary and metastatic prostate cancers, as well as their individual contributions to chemoresistance.

METHODS

Akt isoforms and E-cadherin were manipulated with drugs, knocked down, and over expressed. Tumor cell killing was determined in vitro and in vivo. Overall survival was calculated from patient records and specimens.

RESULTS

Pan-Akt inhibition sensitized tumor cells to chemotherapy, and specific blockade of Akt1 or/and Akt2 caused cells to be more chemoresponsive. Overexpression of Akt3 induced apoptosis. A low dose of Akt1 or Akt2 inhibitor enabled standard chemotherapies to significantly eradicate metastatic prostate tumors in a mouse model, acting as chemosensitizers. In human specimens, we found Akt1 and Akt2 positively correlated, whereas Akt3 inversely correlated, with the overall survival of prostate cancer patients. Akt1high/Akt2high/Akt3low tumors had the worst outcomes.

CONCLUSIONS

E-cadherin-induced activation of Akt1/2 isoforms was the essential mechanism of chemoresistance, whereas Akt3 made cells more fragile. These findings emphasized the need to target Akt1/2, rather than pan-Akt, as a rational therapeutic approach.

Phenotypic Heterogeneity and Metastasis of Breast Cancer Cells

Although intratumoral genomic heterogeneity can impede cancer research and treatment, less is known about the effects of phenotypic heterogeneities. To investigate the role of cell migration heterogeneities in metastasis, we phenotypically sorted metastatic breast cancer cells into two subpopulations based on migration ability. Although migration is typically considered to be associated with metastasis, when injected orthotopically in vivo, the weakly migratory subpopulation metastasized significantly more than the highly migratory subpopulation. To investigate the mechanism behind this observation, both subpopulations were assessed at each stage of the metastatic cascade, including dissemination from the primary tumor, survival in the circulation, extravasation, and colonization. Although both subpopulations performed each step successfully, weakly migratory cells presented as circulating tumor cell (CTC) clusters in the circulation, suggesting clustering as one potential mechanism behind the increased metastasis of weakly migratory cells. RNA sequencing revealed weakly migratory subpopulations to be more epithelial and highly migratory subpopulations to be more mesenchymal. Depletion of E-cadherin expression from weakly migratory cells abrogated metastasis. Conversely, induction of E-cadherin expression in highly migratory cells increased metastasis. Clinical patient data and blood samples showed that CTC clustering and E-cadherin expression are both associated with worsened patient outcome. This study demonstrates that deconvolving phenotypic heterogeneities can reveal fundamental insights into metastatic progression. More specifically, these results indicate that migratory ability does not necessarily correlate with metastatic potential and that E-cadherin promotes metastasis in phenotypically sorted breast cancer cell subpopulations by enabling CTC clustering. SIGNIFICANCE: This study employs phenotypic cell sorting for migration to reveal a weakly migratory, highly metastatic breast cancer cell subpopulation regulated by E-cadherin, highlighting the dichotomy between cancer cell migration and metastasis.

PD-L1 recruits phospholipase C and enhances tumorigenicity of lung tumors harboring mutant forms of EGFR

Cancer immunotherapy focuses on inhibitors of checkpoint proteins, such as programmed death ligand 1 (PD-L1). Unlike RAS-mutated lung cancers, EGFR mutant tumors have a generally low response to immunotherapy. Because treatment outcomes vary by EGFR allele, intrinsic and microenvironmental factors may be involved. Among all non-immunological signaling pathways surveyed in patients’ datasets, EGFR signaling is best associated with high PD-L1. Correspondingly, active EGFRs stabilize PD-L1 transcripts and depletion of PD-L1 severely inhibits EGFR-driven tumorigenicity and metastasis in mice. The underlying mechanisms involve the recruitment of phospholipase C-γ1 (PLC-γ1) to a cytoplasmic motif of PD-L1, which enhances PLC-γ1 activation by EGFR. Once stimulated, PLC-γ1 activates calcium flux, Rho GTPases, and protein kinase C, collectively promoting an aggressive phenotype. Anti-PD-L1 antibodies can inhibit these intrinsic functions of PD-L1. Our results portray PD-L1 as a molecular amplifier of EGFR signaling and improve the understanding of the resistance of EGFR⁺ tumors to immunotherapy.

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Unlike promoter-mediated PD-L1 induction by IFN-γ, EGFR rapidly stabilizes PD-L1 mRNA

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Once induced, PD-L1 enhances metastasis in vivo and chemotaxis toward EGF

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PD-L1 physically binds with and enhances activation of phospholipase C-γ1 by EGFR

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PLC-γ1 binds a PD-L1’s cytoplasmic segment implicated in protection from cytotoxicity

Par-4 activation restrains EMT-induced chemoresistance in PDAC by attenuating MDM-2

BACKGROUND

We recently reported prostate apoptosis response 4 (Par-4), a potential tumor suppressor protein restrains epithelial-mesenchymal transition (EMT) properties and promotes mesenchymal-epithelial transition (MET) in invasive cancer cells by repressing Twist-1 promoter activity. Here, we demonstrate that genetic as well as pharmacological modulation of Par-4 by NGD16 (a small molecule antimetastatic agent), limits EMT-induced chemoresistance in aggressive cancer cells by suppressing MDM-2, a downstream effector of Twist-1.

METHODS

Matrigel invasion assay, gelatin degradation assay, cell scattering assay, MTT assay and colony formation assay were used to study the proliferation and migration abilities of invasive cancer cells. Immunoblotting, immunocytochemistry, and immunoprecipitation analysis were utilized for determining protein expression and protein-protein interaction. 4T1 aggressive mouse carcinoma model was employed to evaluate tumor growth and lung metastasis.

RESULTS

Treatment of gemcitabine (nucleoside analogue anticancer agent) to pancreatic cancer (Panc-1, MiaPaca-2) and breast cancer (MDA-MB-231) cells amplified MDM-2 expression along with increase in EMT properties. Conversely, NGD16 boosted expression of tumor suppressor Par-4 and inhibited invasion and migration abilities of these cells. Moreover, induction of Par-4 effectively diminished MDM-2 along with pro-EMT markers, whereas, augmented the expression of epithelial markers. Furthermore, siRNA-mediated silencing of Par-4 divulged that NGD16 exerts its EMT inhibitory effects in a Par-4-dependent manner. Mechanistically, Par-4 activation provokes p53 by disrupting MDM-2-p53 interaction, which restored epithelial characteristics in cancer cells. Additionally, partial knockdown of MDM-2 through siRNA pronounced the anti-proliferative and anti-invasive effects of NGD16. Finally, NGD16 efficiently inhibited tumor growth and lung metastasis in mouse mammary carcinoma model without showing any undesirable effects.

CONCLUSION

Our findings unveil Par-4 as a key therapeutic target and NGD16 (the pharmacological modulator of Par-4) are potential tools to suppress EMT and associated chemoresistance, which could be exploited clinically for the treatment of aggressive cancers.

A Perspective on Therapeutic Pan-Resistance in Metastatic Cancer

Metastatic spread represents the leading cause of disease-related mortality among cancer patients. Many cancer patients suffer from metastatic relapse years or even decades after radical surgery for the primary tumor. This clinical phenomenon is explained by the early dissemination of cancer cells followed by a long period of dormancy. Although dormancy could be viewed as a window of opportunity for therapeutic interventions, dormant disseminated cancer cells and micrometastases, as well as emergent outgrowing macrometastases, exhibit a generalized, innate resistance to chemotherapy and even immunotherapy. This therapeutic pan-resistance, on top of other adaptive responses to targeted agents such as acquired mutations and lineage plasticity, underpins the current difficulties in eradicating cancer. In the present review, we attempt to provide a framework to understand the underlying biology of this major issue.

Secretome analysis reveals upregulated granzyme B in human androgen-repressed prostate cancer cells with mesenchymal and invasive phenotype

Epithelial-mesenchymal transition (EMT) is a critical early step in cancer metastasis and a complex process that involves multiple factors. In this study, we used proteomics approaches to investigate the secreted proteins (secretome) of paired human androgen-repressed prostate cancer (ARCaP) cell lines, representing the epithelial (ARCaP-E) and mesenchymal (ARCaP-M) phenotypes. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) analyses showed high levels of proteins involved in bone remodeling and extracellular matrix degradation in the ARCaP-M cells, consistent with the bone metastasis phenotype. Furthermore, LC-MS/MS showed a significantly higher level of the serine protease granzyme B (GZMB) in ARCaP-M conditioned media (CM) compared to that of ARCaP-E. Using quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR) to detect mRNA and Western blot to detect protein expression, we further demonstrated that the GZMB gene was expressed by ARCaP-M and the protein was secreted extracellularly. ARCaP-M cells with GZMB gene knockdown using small interfering RNA (siRNA) have markedly reduced invasiveness as demonstrated by the Matrigel invasion assay in comparison with the scrambled siRNA negative control. This study reports that GZMB secretion by mesenchymal-like androgen-repressed human prostate cancer cells promotes invasion, suggesting a possible extracellular role for GZMB in addition to its classic role in immune cell-mediated cytotoxicity.

Study on the Drug Targets and Molecular Mechanisms of Rhizoma Curcumae in the Treatment of Nasopharyngeal Carcinoma Based on Network Pharmacology

Aim

To analyse the target of Rhizoma Curcumae in nasopharyngeal carcinoma by using network pharmacological techniques and to explore the associated molecular mechanism.

Methods

The targets of nasopharyngeal carcinoma were retrieved from the GeneCards database. At the same time, the drug therapeutic targets of Rhizoma Curcumae were obtained from the TCMSP and SymMap databases. The data were imported into the STRING database and Cytoscape 3.7.1 to construct a network of “Chinese medicine component-target-disease” interactions; then, the intersection was screened as the core Rhizoma Curcumae antinasopharyngeal cancer targets. Through GO target function and KEGG pathway enrichment analyses of the core targets, we predicted the biological processes and key signalling pathways involved in the Rhizoma Curcumae treatment of nasopharyngeal carcinoma.

Results

Twenty-five core targets of Rhizoma Curcumae in nasopharyngeal carcinoma were mined: TP53, BCL2 ICAM1 RXRA, TLR3 and TLR9, TNF, PTGS2, IL-6, CTSD, MMP2, MMP9, MMP14, TIMP2, ABCC1, ABCB1, ABCG2, and so on. The results of visual analysis showed that the Rhizoma Curcumae treatment of nasopharyngeal carcinoma mainly involves leukocyte adhesion to vascular endothelial cells, positive regulation of NF-κB import into the nucleus, regulation of the reactive oxygen species biosynthetic and metabolic process, regulation of the chemokine biosynthetic and metabolic process, various cancer-related signalling pathways, and a variety of cytokine signal transduction pathways, such as the NF-κB, TLR, IL-17, and TNF signalling pathways.

Conclusion

The core targets predicted by our research can be used as molecular markers for the treatment and prediction of nasopharyngeal carcinoma. The mechanism of Rhizoma Curcumae treatment in NPC may be related to immune regulatory pathways, the inhibition of cancer cell proliferation, metastasis, and angiogenesis, as well as the regulation of tumour microenvironment. Combined with the prediction of its associated mechanism of action, the core targets can provide targeted reference value for subsequent drug development related to Curcuma.

Sinomenine Inhibits Migration and Invasion of Human Lung Cancer Cell through Downregulating Expression of miR-21 and MMPs

Sinomenine is an alkaloid derived from Sinomenium acutum. Recent studies have found that sinomenine can inhibit various cancers by inhibiting the proliferation, migration and invasion of tumors and inducing apoptosis. This study aims to investigate the effect and mechanism of sinomenine on inhibiting the migration and invasion of human lung adenocarcinoma cells in vitro. The results demonstrate that viabilities of A549 and H1299 cells were inhibited by sinomenine in a dose-dependent manner. When treated with sub-toxic doses of sinomenine, cell migration and invasion are markedly suppressed. Sinomenine decreases the mRNA level of matrix metalloproteinase-2 (MMP-2), MMP-9, and the extracellular inducer of matrix metalloproteinase (EMMPRIN/CD147), but elevates the expression of reversion-inducing cysteine-rich proteins with kazal motifs (RECK) and the tissue inhibitor of metalloproteinase-1 (TIMP-1) and TIMP-2. In addition, sinomenine significantly increases the expression of the epithelial marker E-cadherin but concomitantly decreases the expression of the mesenchymal marker vimentin, suggesting that it suppresses epithelial–mesenchymal transition (EMT). Moreover, sinomenine downregulates oncogenic microRNA-21 (miR-21), which has been known to target RECK. The downregulation of miR-21 decreases cell invasion, while the upregulation of miR-21 increases cell invasion. Furthermore, the downregulation of miR-21 stimulates the expression of RECK, TIMP-1/-2, and E-cadherin, but reduces the expression of MMP-2/-9, EMMPRIN/CD147, and vimentin. Taken together, the results reveal that the inhibition of A549 cell invasion by sinomenine may, at least in part, be through the downregulating expression of MMPs and miR-21. These findings demonstrate an attractive therapeutic potential for sinomenine in lung cancer anti-metastatic therapy.

The CC and CXC chemokines: major regulators of tumor progression and the tumor microenvironment

Chemokines are a family of soluble cytokines that act as chemoattractants to guide the migration of cells, in particular of immune cells. However, chemokines are also involved in cell proliferation, differentiation, and survival. Chemokines are associated with a variety of human diseases including chronic inflammation, immune dysfunction, cancer, and metastasis. This review discusses the expression of CC and CXC chemokines in the tumor microenvironment and their supportive and inhibitory roles in tumor progression, angiogenesis, metastasis, and tumor immunity. We also specially focus on the diverse roles of CXC chemokines (CXCL9-11, CXCL4 and its variant CXCL4L1) and their two chemokine receptor CXCR3 isoforms, CXCR3-A and CXCR3-B. These two distinct isoforms have divergent roles in tumors, either promoting (CXCR3-A) or inhibiting (CXCR3-B) tumor progression. Their effects are mediated not only directly in tumor cells but also indirectly via the regulation of angiogenesis and tumor immunity. A full comprehension of their mechanisms of action is critical to further validate these chemokines and their receptors as biomarkers or therapeutic targets in cancer.

Expression of E-cadherin and specific CXCR3 isoforms impact each other in prostate cancer

Background

Carcinoma cells shift between epithelial and mesenchymal phenotypes during cancer progression, as defined by surface presentation of the cell-cell cohesion molecule E-cadherin, affecting dissemination, progression and therapy responsiveness. Concomitant with the loss of E-cadherin during the mesenchymal transition, the predominant receptor isoform for ELR-negative CXC ligands shifts from CXCR3-B to CXCR3-A which turns this classical G-protein coupled receptor from an inhibitor to an activator of cell migration, thus promoting tumor cell invasiveness. We proposed that CXCR3 was not just a coordinately changed receptor but actually a regulator of the cell phenotype.

Methods

Immunoblotting, immunofluorescence, quantitative real-time PCR and flow cytometry assays investigated the expression of E-cadherin and CXCR3 isoforms. Intrasplenic inoculation of human prostate cancer (PCa) cells with spontaneous metastasis to the liver analyzed E-cadherin and CXCR3-B expression during cancer progression in vivo.

Results

We found reciprocal regulation of E-cadherin and CXCR3 isoforms. E-cadherin surface expression promoted CXCR3-B presentation on the cell membrane, and to a lesser extent increased its mRNA and total protein levels. In turn, forced expression of CXCR3-A reduced E-cadherin expression level, whereas CXCR3-B increased E-cadherin in PCa. Meanwhile, a positive correlation of E-cadherin and CXCR3-B expression was found both in experimental PCa liver micro-metastases and patients’ tissue.

Conclusions

CXCR3-B and E-cadherin positively correlated in vitro and in vivo in PCa cells and liver metastases, whereas CXCR3-A negatively regulated E-cadherin expression. These results suggest that CXCR3 isoforms may play important roles in cancer progression and dissemination via diametrically regulating tumor’s phenotype.

Controversies around epithelial-mesenchymal plasticity in cancer metastasis

Experimental evidence accumulated over decades has implicated epithelial-mesenchymal plasticity (EMP), which collectively encompasses epithelial-mesenchymal transition and the reverse process of mesenchymal-epithelial transition, in tumour metastasis, cancer stem cell generation and maintenance, and therapeutic resistance. However, the dynamic nature of EMP processes, the apparent need to reverse mesenchymal changes for the development of macrometastases and the likelihood that only minor cancer cell subpopulations exhibit EMP at any one time have made such evidence difficult to accrue in the clinical setting. In this Perspectives article, we outline the existing preclinical and clinical evidence for EMP and reflect on recent controversies, including the failure of initial lineage-tracing experiments to confirm a major role for EMP in dissemination, and discuss accumulating data suggesting that epithelial features and/or a hybrid epithelial-mesenchymal phenotype are important in metastasis. We also highlight strategies to address the complexities of therapeutically targeting the EMP process that give consideration to its spatially and temporally divergent roles in metastasis, with the view that this will yield a potent and broad class of therapeutic agents.

Role of TGF‑β in the motility of ShcD‑overexpressing 293 cells

The newly identified Src homology and collagen (Shc) family member ShcD was observed to be upregulated in 50% of vertical growth phase and metastatic melanomas. The aim of the present study was to investigate the mechanism by which ShcD mediates cell motility. 293 cell lines were altered to stably express GFP (GF) or GFP‑ShcD (G5). Treatment of the cells with transforming growth factor (TGF)β2 promoted extracellular signal‑regulated kinase (ERK) phosphorylation and, to a lesser extent, Smad2 phosphorylation in GFP‑ShcD‑expressing cells but not in GFP‑overexpressing cells. GFP‑ShcD‑expressing cells exhibited upregulated expression of certain epithelial‑mesenchymal transition‑related genes, such as snail family transcriptional repressor 1 and SLUG, than GFP‑expressing cells. Higher levels of ERK were found in the nuclear fraction of GFP‑ShcD‑expressing cells than that of GFP‑expressing cells. Overall, GFP‑ShcD‑expressing cells demonstrated enhanced migration compared with GFP‑expressing cells. A slight increase in cell migration was observed in both cell lines (GF and G5) when the cells were allowed to migrate towards conditioned medium derived from TGFβ2‑treated GFP‑ShcD expressing cells. Collectively, ShcD upregulation was proposed to induce cell migration by affecting the expression of certain epithelial‑mesenchymal transition‑related genes. Thus, our findings may improve understanding of the role of ShcD in cell migration.

Dual role of Par-4 in abrogation of EMT and switching on Mesenchymal to Epithelial Transition (MET) in metastatic pancreatic cancer cells

Epithelial-mesenchymal transition (EMT) is a critical event that occurs during the invasion and metastatic spread of cancer cells. Here, we conceive a dual mechanism of Par-4-mediated inhibition of EMT and induction of MET in metastatic pancreatic cancer cells. First, we demonstrate that 1,1'-β-D-glucopyranosyl-3,3'-bis(5-bromoindolyl)-octyl methane (NGD16), an N-glycosylated derivative of medicinally important phytochemical 3,3'-diindolylmethane (DIM) abrogates EMT by inducing pro-apoptotic protein Par-4. Induction of Par-4 (by NGD16 or ectopic overexpression) strongly impedes invasion with inhibition of major mesenchymal markers viz. Vimentin and Twist-1 epithelial marker- E-cadherin. Further, NGD16 triggers MET phenotypes in pancreatic cancer cells by augmenting ALK2/Smad4 signaling in a Par-4-dependent manner. Conversely, siRNA-mediated silencing of endogenous Par-4 unveil reversal of MET with diminished E-cadherin expression and invasive phenotypes. Additionally, we demonstrate that intact Smad4 is essential for Par-4-mediated maintenance of E-cadherin level in MET induced cells. Notably, we imply that Par-4 induction regulates E-cadherin levels in the pancreatic cancer cells via modulating Twist-1 promoter activity. Finally, in vivo studies with syngenic mouse metastatic pancreatic cancer model reveal that NGD16 strongly suppresses metastatic burden, ascites formation, and prolongs the overall survival of animals effectively.

Inferring cell state by quantitative motility analysis reveals a dynamic state system and broken detailed balance

Cell populations display heterogeneous and dynamic phenotypic states at multiple scales. Similar to molecular features commonly used to explore cell heterogeneity, cell behavior is a rich phenotypic space that may allow for identification of relevant cell states. Inference of cell state from cell behavior across a time course may enable the investigation of dynamics of transitions between heterogeneous cell states, a task difficult to perform with destructive molecular observations. Cell motility is one such easily observed cell behavior with known biomedical relevance. To investigate heterogenous cell states and their dynamics through the lens of cell behavior, we developed Heteromotility, a software tool to extract quantitative motility features from timelapse cell images. In mouse embryonic fibroblasts (MEFs), myoblasts, and muscle stem cells (MuSCs), Heteromotility analysis identifies multiple motility phenotypes within the population. In all three systems, the motility state identity of individual cells is dynamic. Quantification of state transitions reveals that MuSCs undergoing activation transition through progressive motility states toward the myoblast phenotype. Transition rates during MuSC activation suggest non-linear kinetics. By probability flux analysis, we find that this MuSC motility state system breaks detailed balance, while the MEF and myoblast systems do not. Balanced behavior state transitions can be captured by equilibrium formalisms, while unbalanced switching between states violates equilibrium conditions and would require an external driving force. Our data indicate that the system regulating cell behavior can be decomposed into a set of attractor states which depend on the identity of the cell, together with a set of transitions between states. These results support a conceptual view of cell populations as dynamical systems, responding to inputs from signaling pathways and generating outputs in the form of state transitions and observable motile behaviors.

CD44/CD44v6 a Reliable Companion in Cancer-Initiating Cell Maintenance and Tumor Progression

Metastasis is the leading cause of cancer death, tumor progression proceeding through emigration from the primary tumor, gaining access to the circulation, leaving the circulation, settling in distant organs and growing in the foreign environment. The capacity of a tumor to metastasize relies on a small subpopulation of cells in the primary tumor, so called cancer-initiating cells (CIC). CIC are characterized by sets of markers, mostly membrane anchored adhesion molecules, CD44v6 being the most frequently recovered marker. Knockdown and knockout models accompanied by loss of tumor progression despite unaltered primary tumor growth unraveled that these markers are indispensable for CIC. The unexpected contribution of marker molecules to CIC-related activities prompted research on underlying molecular mechanisms. This review outlines the contribution of CD44, particularly CD44v6 to CIC activities. A first focus is given to the impact of CD44/CD44v6 to inherent CIC features, including the crosstalk with the niche, apoptosis-resistance, and epithelial mesenchymal transition. Following the steps of the metastatic cascade, we report on supporting activities of CD44/CD44v6 in migration and invasion. These CD44/CD44v6 activities rely on the association with membrane-integrated and cytosolic signaling molecules and proteases and transcriptional regulation. They are not restricted to, but most pronounced in CIC and are tightly regulated by feedback loops. Finally, we discuss on the engagement of CD44/CD44v6 in exosome biogenesis, loading and delivery. exosomes being the main acteurs in the long-distance crosstalk of CIC with the host. In brief, by supporting the communication with the niche and promoting apoptosis resistance CD44/CD44v6 plays an important role in CIC maintenance. The multifaceted interplay between CD44/CD44v6, signal transducing molecules and proteases facilitates the metastasizing tumor cell journey through the body. By its engagement in exosome biogenesis CD44/CD44v6 contributes to disseminated tumor cell settlement and growth in distant organs. Thus, CD44/CD44v6 likely is the most central CIC biomarker.

Circulating Tumor Cells and Implications of the Epithelial-to-Mesenchymal Transition

The majority of cancer-related deaths result from metastasis, the process by which cancer cells escape the primary tumor site and enter into the blood circulation in order to disseminate to secondary locations throughout the body. Tumor cells found within the circulation are referred to as circulating tumor cells (CTCs), and their detection and enumeration correlate with poor prognosis. The epithelial-to-mesenchymal transition (EMT) is a dynamic process that imparts epithelial cells with mesenchymal-like properties, thus facilitating tumor cell dissemination and contributing to metastasis. However, EMT also results in the downregulation of various epithelial proteins typically utilized by CTC technologies for enrichment and detection of these rare cells, resulting in reduced detection of some CTCs, potentially those with a more metastatic phenotype. In addition to the current clinical role of CTCs as a prognostic biomarker, they also have potential as a predictive biomarker via CTC characterization. However, CTC characterization is complicated by the unknown biological significance of CTCs possessing an EMT-like phenotype, and the ability to capture and understand this CTC subpopulation is an essential step in the utilization of CTCs for patient management. This chapter will review the process of EMT and its contribution to metastasis; discusses current and future clinical applications of CTCs; and describes both traditional and novel methods for CTC enrichment, detection, and characterization with a specific focus on CTCs with an EMT phenotype.

Human salivary peptide histatin-1 stimulates epithelial and endothelial cell adhesion and barrier function

Histatins are multifunctional histidine-rich peptides secreted by the salivary glands and exclusively present in the saliva of higher primates, where they play a fundamental role in the protection of the oral cavity. Our previously published results demonstrated that histatin-1 (Hst1) promotes cell-substrate adhesion in various cell types and hinted that it could also be involved in cell-cell adhesion, a process of fundamental importance to epithelial and endothelial barriers. Here we explore the effects of Hst1 on cellular barrier function. We show that Hst1 improved endothelial barrier integrity, decreased its permeability for large molecules, and prevented translocation of bacteria across epithelial cell layers. These effects are mediated by the adherens junction protein E-cadherin (E-cad) and by the tight junction protein zonula occludens 1, as Hst1 increases the levels of zonula occludens 1 and of active E-cad. Hst1 may also promote epithelial differentiation as Hst1 induced transcription of the epithelial cell differentiation marker apolipoprotein A-IV (a downstream E-cad target). In addition, Hst1 counteracted the effects of epithelial-mesenchymal transition inducers on the outgrowth of oral cancer cell spheroids, suggesting that Hst1 affects processes that are implicated in cancer progression.-Van Dijk, I. A., Ferrando, M. L., van der Wijk, A.-E., Hoebe, R. A., Nazmi, K., de Jonge, W. J., Krawczyk, P. M., Bolscher, J. G. M., Veerman, E. C. I., Stap, J. Human salivary peptide histatin-1 stimulates epithelial and endothelial cell adhesion and barrier function.

miR-21 and KLF4 jointly augment epithelial‑mesenchymal transition via the Akt/ERK1/2 pathway

miR-21 induces epithelial-mesenchymal transition (EMT) of human cholangiocarcinoma (CCA) cells. However, the mechanism by which this occurs remains unclear. In the present study, high throughput platform was employed to detect the genes that are differential expressed in QBC939 cells transfected with a hsa-miR-21 antagomir or control vectors. The EMT-related Krüppel-like factor 4 (KLF4) gene was down-regulated after miR-21 was knocked down. Overexpression of miR-21 upregulated KLF4, Akt, ERK and mesenchymal cell markers (N-cadherin and vimentin), downregulated the expression of epithelial cell marker E-cadherin and reduced cell migration and invasion. Immunohistochemistry showed that KLF4, pAkt and pERK were upregulated in tumor xenografts transfected with miR-21 mimics. Inhibitors of the PI3K-Akt and ERK1/2 pathways, LY294002 and U0126, significantly suppressed the EMT phenotype. The present data demonstrated that overexpression of miR-21, accompanied with KLF4, augmented the EMT via inactivation of Akt and ERK1/2 pathways. In conclusion, we have identified a novel mechanism that may be targeted in an attempt to relieve the malignant biological behavior of CCA cells.

Liver protects metastatic prostate cancer from induced death by activating E-cadherin signaling

Liver is one of the most common sites of cancer metastasis. Once disseminated, the prognosis is poor as these tumors often display generalized chemoresistance, particularly for carcinomas that derive not from the aerodigestive tract. When these cancers seed the liver, the aggressive cells usually undergo a mesenchymal to epithelial reverting transition that both aids colonization and renders the tumor cells chemoresistant. In vitro studies demonstrate that hepatocytes drive this phenotypic shift. However, the in vivo evidence and the molecular signals that protect these cells from induced death are yet to be defined. Herein, we report that membrane surface E-cadherin-expressing prostate cancer cells were resistant to cell death by chemotherapeutic drugs but E-cadherin null cells or those expressing E-cadherin only in the cytoplasm were sensitive to death signals and chemotherapies both in vitro and in vivo. While cell-cell E-cadherin ligandation reduced mitogenesis, this chemoprotection was proliferation-independent as killing of both 5-ethynyl-2'-deoxyuridine-positive (or Ki67⁺ ) and 5-ethynyl-2'-deoxyuridine-negative (Ki67^- ) cells was inversely related to membrane-bound E-cadherin. Inhibiting the canonical survival kinases extracellular signal-regulated protein kinases, protein kinase B, and Janus kinase, which are activated by chemotherapeutics in epithelial cell-transitioned prostate cancer, abrogated the chemoresistance both in cell culture and in animal models of metastatic cancer. For disseminated tumors, protein kinase B disruption in itself had no effect on tumor survival but was synergistic with chemotherapy, leading to increased killing.

CONCLUSION

Liver microenvironment-driven phenotypic switching of carcinoma cells and subsequent survival signaling results in activation of canonical survival pathways that protect the disseminated prostate cancer liver micrometastases in a proliferation-independent manner, and these pathways can be targeted as an adjuvant treatment to improve the efficacy of traditional chemotherapeutics (Hepatology 2016;64:1725-1742).

Imaging Cancer Angiogenesis and Metastasis in a Zebrafish Embryo Model

Tumor angiogenesis and metastasis are key steps of cancer progression. In vitro and animal model studies have contributed to partially elucidating the mechanisms involved in these processes and in developing therapies. Besides the improvements in fundamental research and the optimization of therapeutic regimes, cancer still remains a major health threatening condition and therefore the development of new models is needed. The zebrafish is a powerful tool to study tumor angiogenesis and metastasis, because it allows the visualization of fluorescently labelled tumor cells inducing vessel remodeling, disseminating and invading surrounding tissues in a whole transparent embryo. The embryo model has also been used to address the contribution of the tumor stroma in sustaining tumor angiogenesis and spreading. Simultaneously, new anti-angiogenic drugs and compounds affecting malignant cell survival and migration can be tested by simply adding the compound into the water of living embryos. Therefore the zebrafish model offers the opportunity to gain more knowledge on cancer angiogenesis and metastasis in vivo with the final aim of providing new translational insights into therapeutic approaches to help patients.

Plasticity of Cancer Cell Invasion-Mechanisms and Implications for Therapy

Cancer cell migration is a plastic and adaptive process integrating cytoskeletal dynamics, cell-extracellular matrix and cell-cell adhesion, as well as tissue remodeling. In response to molecular and physical microenvironmental cues during metastatic dissemination, cancer cells exploit a versatile repertoire of invasion and dissemination strategies, including collective and single-cell migration programs. This diversity generates molecular and physical heterogeneity of migration mechanisms and metastatic routes, and provides a basis for adaptation in response to microenvironmental and therapeutic challenge. We here summarize how cytoskeletal dynamics, protease systems, cell-matrix and cell-cell adhesion pathways control cancer cell invasion programs, and how reciprocal interaction of tumor cells with the microenvironment contributes to plasticity of invasion and dissemination strategies. We discuss the potential and future implications of predicted "antimigration" therapies that target cytoskeletal dynamics, adhesion, and protease systems to interfere with metastatic dissemination, and the options for integrating antimigration therapy into the spectrum of targeted molecular therapies.

β-Asarone inhibits gastric cancer cell proliferation

β-Asarone is the main volatile oil of Chinese herb Rhizoma Acori Tatarinowii. It exhibits a wide range of biological activities in many human organs. However, few studies have investigated the effect of β-asarone on gastric cancer. The present study investigated the effect of β-asarone on the proliferation and apoptosis of three types of differentiated human gastric cancer cell lines (SGC-7901, BGC-823 and MKN-28) in vitro as well as the related molecular mechanisms. Methyl thiazolyl tetrazolium assay, Annexin V/PI double staining, immunofluorescence test and transmission electron microscopy all confirmed that β-asarone had an obvious dose-dependent inhibitive effect on the proliferation of human gastric cancer cells and induced apoptosis of the cell lines. Transwell invasion, wound-healing and matrix‑cell adhesion experiments confirmed that β-asarone inhibited the invasion, migration and adhesion of human gastric cancer BGC-823 cells. Quantitative real-time PCR and western blotting found that β-asarone significantly activated caspase-3, caspase-8, caspase-9, Bax, Bak and suppressed Bcl-2, Bcl-xL and survivin activity. Moreover, β-asarone increased the expression of RECK, E-cadherin and decreased the expression of MMP-2, MMP-9, MMP-14 and N-cadherin. The present study demonstrated that β-asarone effectively inhibits the proliferation of human gastric cancer cells, induces their apoptosis and decreased the invasive, migratory and adhesive abilities.

Angiomotin like-1 is a novel component of the N-cadherin complex affecting endothelial/pericyte interaction in normal and tumor angiogenesis

Transmission of mechanical force via cell junctions is an important component that molds cells into shapes consistent with proper organ function. Of particular interest are the cadherin transmembrane proteins, which play an essential role in connecting cell junctions to the intra-cellular cytoskeleton. Understanding how these biomechanical complexes orchestrate intrinsic and extrinsic forces is important for our understanding of the underlying mechanisms driving morphogenesis. We have previously identified the Amot protein family, which are scaffold proteins that integrate polarity, junctional, and cytoskeletal cues to modulate cellular shape in endothelial as well as epithelial cells. In this report, we show that AmotL1 is a novel partner of the N-cadherin protein complex. We studied the role of AmotL1 in normal retinal as well as tumor angiogenesis using inducible endothelial-specific knock-out mice. We show that AmotL1 is essential for normal establishment of vascular networks in the post-natal mouse retina as well as in a transgenic breast cancer model. The observed phenotypes were consistent with a non-autonomous pericyte defect. We show that AmotL1 forms a complex with N-cadherin present on both endothelial cells and pericytes. We propose that AmotL1 is an essential effector of the N-cadherin mediated endothelial/pericyte junctional complex.

Regulation of epithelial-mesenchymal transition through epigenetic and post-translational modifications

The epithelial to mesenchymal transition (EMT) is a biological process in which a non-motile epithelial cell changes to a mesenchymal phenotype with invasive capacities. This phenomenon has been well documented in multiple biological processes including embryogenesis, fibrosis, tumor progression and metastasis. The hallmark of EMT is the loss of epithelial surface markers, most notably E-cadherin, and the acquisition of mesenchymal markers including vimentin and N-cadherin. The downregulation of E-cadherin during EMT can be mediated by its transcriptional repression through the binding of EMT transcription factors (EMT-TFs) such as SNAIL, SLUG and TWIST to E-boxes present in the E-cadherin promoter. Additionally, EMT-TFs can also cooperate with several enzymes to repress the expression of E-cadherin and regulate EMT at the epigenetic and post- translational level. In this review, we will focus on epigenetic and post- translational modifications that are important in EMT. In addition, we will provide an overview of the various therapeutic approaches currently being investigated to undermine EMT and hence, the metastatic progression of cancer as well.

Atypical RhoV and RhoU GTPases control development of the neural crest

This review addresses the developmental roles of 2 GTPases of the Rho family, RhoV/Chp and RhoU/Wrch. These two GTPases form a distinct subfamily related to Rac and Cdc42 proteins and were detected in a screen for Rho members that are particularly expressed in the neural crest, an embryonic tissue peculiar to vertebrates. The neural crest represents a physiological model of normal epithelial to mesenchymal transition (EMT), in which epithelial cells at the border of neural and non-neural ectoderm differentiate, lose their intercellular connections and migrate throughout the embryo. We showed that RhoV, transiently induced by the canonical Wnt pathway, is required for the full differentiation of neural crest cells, while RhoU, induced later by the non-canonical Wnt pathway, is necessary for the migration process. These two GTPases, which are highly conserved across vertebrates, are thus tightly functionally linked to Wnt signaling, whose implication in embryonic development and cancer progression is well established. In the light of the recent literature, we discuss how RhoV and RhoU may achieve their physiological functions.

ZEB1 promotes the progression and metastasis of cervical squamous cell carcinoma via the promotion of epithelial-mesenchymal transition

OBJECTIVE

The process of epithelial-mesenchymal transition (EMT) clearly contributes to cancer metastasis. The aim of this study was to investigate the expression of the EMT-related transcription repressor ZEB1 and the expression of EMT-associated markers (E-cadherin, β-catenin and N-cadherin) in cervical squamous cell carcinoma. In addition, the role of ZEB1 and these EMT-associated markers in the progression and metastasis of cervical squamous cell carcinoma was explored.

METHODS

The expression of ZEB1, E-cadherin, β-catenin and N-cadherin was evaluated in 81 specimens of cervical squamous cell carcinoma by immunohistochemistry; the clinicopathological significance of these markers was then analyzed.

RESULTS

1) Of the 81 samples, 37 cases (45.7%) were positive for ZEB1, and nuclear expression of ZEB1 in tumor cells was positively associated with the differentiation status of the tumor tissue (P < 0.05), vascular invasion (P < 0.05) and lymph node metastasis (P < 0.05). 2) The loss of E-cadherin and β-catenin expression in tumor cells and the acquisition of N-cadherin expression were positively associated with the differentiation status of the tumor tissue (P < 0.05) and with the occurrence of vascular invasion (P < 0.05). 3) A significant negative correlation was observed between ZEB1 and E-cadherin expression (Spearman = -0.636, P < 0.05) and between ZEB1 and β-catenin expression (Spearman = -0.417, P < 0.05). Moreover, a significant positive correlation was observed between ZEB1 and N-cadherin expression (Spearman = 0.557, P < 0.05).

CONCLUSIONS

These results emphasize the role of EMT in cervical squamous cell carcinoma. The upregulation of ZEB1 is associated with the abnormal expression of E-cadherin, β-catenin and N-cadherin, which might promote the progression and metastasis of cervical squamous cell carcinoma.

[Role of cadherins in health and in developing breast cancer]

The review gives data on the structure of cadherin cell adhesion molecules, their role in the body's development and malignant tumor progression. It describes cadherins that are considered to play the most important role in the development of a tumor process: E-, P-, and N-cadherins that belong to type I classical cadhedrins and VE-cadhedrin that does to type II cadherins. Particular emphasis is placed on the signal mechanisms with involvement of cadherins and cadherin-related molecules, which are realized in the body in health and in tumor transformation of cells.

Expression of E-cadherin in oral lichen planus

Oral lichen planus (OLP) is a common lesion of the oral mucosa that can progress to cancer. E-cadherin is involved in intercellular adherence and the pathogenesis, development and metastasis of tumors, and is considered to be an important indicator of tumor progression and prognosis. The aim of this study was to investigate the expression of E-cadherin in OLP in order to elucidate its role in the pathogenesis and malignant transformation of OLP and provide evidence to support the early diagnosis and treatment of OLP with malignant potential. OLP specimens (n=52) and samples of normal oral mucosa (n=41) as the control were collected. Immunohistochemical staining was conducted to reveal the expression of E-cadherin in the OLP samples and normal oral mucosa. It was observed that 25 of the 52 OLP specimens exhibited normal positive expression of E-cadherin and 27 exhibited abnormal positive expression, corresponding to an abnormal positive rate of 51.92%. In the normal oral mucosa group, 39 of the 41 cases exhibited normal positive expression and 2 exhibited abnormal positive expression. The abnormal positive rate in the normal oral mucosa was 4.88%, which was significantly lower than that in the OLP group. The significantly elevated rate of abnormal positive expression of E-cadherin in the OLP group indicates the involvement of E-cadherin in the malignant transformation of OLP and supports the malignant potential of OLP.

Lysophosphatidic Acid Initiates Epithelial to Mesenchymal Transition and Induces β-Catenin-mediated Transcription in Epithelial Ovarian Carcinoma

During tumor progression, epithelial ovarian cancer (EOC) cells undergo epithelial-to-mesenchymal transition (EMT), which influences metastatic success. Mutation-dependent activation of Wnt/β-catenin signaling has been implicated in gain of mesenchymal phenotype and loss of differentiation in several solid tumors; however, similar mutations are rare in most EOC histotypes. Nevertheless, evidence for activated Wnt/β-catenin signaling in EOC has been reported, and immunohistochemical analysis of human EOC tumors demonstrates nuclear staining in all histotypes. This study addresses the hypothesis that the bioactive lipid lysophosphatidic acid (LPA), prevalent in the EOC microenvironment, functions to regulate EMT in EOC. Our results demonstrate that LPA induces loss of junctional β-catenin, stimulates clustering of β1 integrins, and enhances the conformationally active population of surface β1 integrins. Furthermore, LPA treatment initiates nuclear translocation of β-catenin and transcriptional activation of Wnt/β-catenin target genes resulting in gain of mesenchymal marker expression. Together these data suggest that LPA initiates EMT in ovarian tumors through β1-integrin-dependent activation of Wnt/β-catenin signaling, providing a novel mechanism for mutation-independent activation of this pathway in EOC progression.

Cell membrane fluid-mosaic structure and cancer metastasis

Cancer cells are surrounded by a fluid-mosaic membrane that provides a highly dynamic structural barrier with the microenvironment, communication filter and transport, receptor and enzyme platform. This structure forms because of the physical properties of its constituents, which can move laterally and selectively within the membrane plane and associate with similar or different constituents, forming specific, functional domains. Over the years, data have accumulated on the amounts, structures, and mobilities of membrane constituents after transformation and during progression and metastasis. More recent information has shown the importance of specialized membrane domains, such as lipid rafts, protein-lipid complexes, receptor complexes, invadopodia, and other cellular structures in the malignant process. In describing the macrostructure and dynamics of plasma membranes, membrane-associated cytoskeletal structures and extracellular matrix are also important, constraining the motion of membrane components and acting as traction points for cell motility. These associations may be altered in malignant cells, and probably also in surrounding normal cells, promoting invasion and metastatic colonization. In addition, components can be released from cells as secretory molecules, enzymes, receptors, large macromolecular complexes, membrane vesicles, and exosomes that can modify the microenvironment, provide specific cross-talk, and facilitate invasion, survival, and growth of malignant cells.

Extracellular matrix in obesity – cancer interactions

Obesity or overweight is a risk factor for several health disorders such as type 2 diabetes, hypertension, and certain cancers. Furthermore, obesity affects almost all body systems including the extracellular matrix (ECM) by generating a pro-inflammatory environment, which are associated with abnormal secretions of several cytokines or hormonal substances, for example, insulin-like growth factors (IGFs), leptin, and sex hormones. These chemical mediators most likely have a great impact on the ECM. Accumulating evidence suggests that both obesity and ECM can influence tumor growth and progression through a number of chemical mediators. Conversely, cells in the connective tissue, namely fibroblasts and macrophages, support and aggravate the inflammatory situation in obesity by releasing several cytokines or growth factors such as vascular endothelial growth factor, epidermal growth factor, and transforming growth factor-beta (TGF-β). A wide range of functions are performed by TGF-β in normal health and pathological conditions including tumorigenesis. Breast cancer in postmenopausal women is a classic example of obesity-related cancer wherein several of these conditions, for example, higher levels of pro-inflammatory cytokines, impairment in the regulation of estrogen and growth factors, and dysregulation of different ECM components may favor the neoplastic process. Aberrant expressions of ECM components such as matrix metalloproteinases or matricellular proteins in both obesity and cancer have been reported by many studies. Nonstructural matricellular proteins, viz., thrombospondins, secreted protein acidic and rich in cysteine (SPARC), and Cyr61-CTGF-Nov (CCN), which function as modulators of cell-ECM interactions, exhibit protean behavior in cancer. Precise understanding of ECM biology can provide potential therapeutic targets to combat obesity-related pathologies.

Protein interactions of cortactin in relation to invadopodia formation in metastatic renal clear cell carcinoma

In the present study, we wanted to examine the predominant factor/s in the initiation of metastasis. We used samples of advanced grades of renal clear cell carcinoma with documented clinical history of vena caval spread as the experimental group. The major rationale for this selection is the fact that renal cell carcinoma metastasize extensively through the inferior vena cava up to the pulmonary bed and often exist as a continuous mass of metastatic tissue. As cortactin plays a significant role in invadopodia formation during initiation of metastasis, in the present study, we tested expression of cortactin and phospho(tyr421)-cortactin in different grades of renal cell clear carcinoma and examined its property to bind to actin. The findings of the present study suggest that the variations of the local physiological milieu are the driving forces for metastasis by enhancing molecular mechanisms for lamellipodia formation. We conclude that localization of cortactin in cancer cells and interaction between actin and its nucleators are crucial for cancer progression.

α-Solanine inhibits invasion of human prostate cancer cell by suppressing epithelial-mesenchymal transition and MMPs expression

α-Solanine, a naturally occurring steroidal glycoalkaloid found in nightshade (Solanum nigrum Linn.), was found to inhibit proliferation and induce apoptosis of tumor cells. However, the mechanism involved in suppression of cancer cell metastasis by α-solanine remains unclear. This study investigates the suppression mechanism of α-solanine on motility of the human prostate cancer cell PC-3. Results show that α-solanine reduces the viability of PC-3 cells. When treated with non-toxic doses of α-solanine, cell invasion is markedly suppressed by α-solanine. α-Solanine also significantly elevates epithelial marker E-cadherin expression, while it concomitantly decreases mesenchymal marker vimentin expression, suggesting it suppresses epithelial-mesenchymal transition (EMT). α-Solanine reduces the mRNA level of matrix metalloproteinase-2 (MMP-2), MMP-9 and extracellular inducer of matrix metalloproteinase (EMMPRIN), but increases the expression of reversion-inducing cysteine-rich protein with kazal motifs (RECK), and tissue inhibitor of metalloproteinase-1 (TIMP-1) and TIMP-2. Immunoblotting assays indicate α-solanine is effective in suppressing the phosphorylation of phosphatidylinositide-3 kinase (PI3K), Akt and ERK. Moreover, α-solanine downregulates oncogenic microRNA-21 (miR-21) and upregulates tumor suppressor miR-138 expression. Taken together, the results suggest that inhibition of PC-3 cell invasion by α-solanine may be, at least in part, through blocking EMT and MMPs expression. α-Solanine also reduces ERK and PI3K/Akt signaling pathways and regulates expression of miR-21 and miR-138. These findings suggest an attractive therapeutic potential of α-solanine for suppressing invasion of prostate cancer cell.

Breast cancer cell invasion mediated by Gα12 signaling involves expression of interleukins-6 and -8, and matrix metalloproteinase-2

Background

Recent studies on the involvement of the G12 family of heterotrimeric G proteins (Gα12 and Gα13, the products of the GNA12 and GNA13 genes, respectively) in oncogenic pathways have uncovered a link between G12 signaling and cancer progression. However, despite a well characterized role of Rho GTPases, the potential role of secreted factors in the capacity of G12 signaling to promote invasion of cancer cells is just beginning to be addressed.

Methods

MDA-MB-231 and MCF10A breast cancer cell lines were employed as a model system to explore the involvement of secreted factors in G12-stimulated cell invasion. Factors secreted by cells expressing dominant-active Gα12 were identified by protein array, and their involvement in breast cancer cell invasion was assessed through both RNAi-mediated knockdown and antibody neutralization approaches. Bioinformatics analysis of the promoter elements of the identified factors suggested NF-κB elements played a role in their enhanced expression, which was tested by chromatin immunoprecipitation.

Results

We found that signaling through the Gα12 in MDA-MB-231 and MCF10A breast cancer cell lines enhances expression of interleukins (IL)-6 and −8, and matrix metalloproteinase (MMP)-2, and that these secreted factors play a role in G12-stimulated cell invasion. Furthermore, the enhanced expression of these secreted factors was found to be facilitated by the activation of their corresponding promoters, where NF-κB seems to be one of the major regulators. Inhibition of IL-6 and IL-8, or MMP-2 activity significantly decreased Gα12-mediated cell invasion.

Conclusions

These studies confirm and extend findings that secreted factors contribute to the oncogenic potential of G12 signaling, and suggest potential therapeutic targets to control this process.

The mitogen-activated protein (MAP) kinases p38 and extracellular signal-regulated kinase (ERK) are involved in hepatocyte-mediated phenotypic switching in prostate cancer cells

The greatest challenge for the seeding of cancer in metastatic sites is integration into the ectopic microenvironment despite the lack of an orthotopic supportive environment and presence of pro-death signals concomitant with a localized "foreign-body" inflammatory response. In this metastatic location, many carcinoma cells display a reversion of the epithelial-to-mesenchymal transition that marks dissemination in the primary tumor mass. This mesenchymal to epithelial reverting transition (MErT) is thought to help seeding and colonization by protecting against cell death. We have previously shown that hepatocyte coculture induces the re-expression of E-cadherin via abrogation of autocrine EGFR signaling pathway in prostate cancer (PCa) cells and that this confers a survival advantage. Herein, we show that hepatocytes educate PCa to undergo MErT by modulating the activity of p38 and ERK1/2. Hepatocytes inhibited p38 and ERK1/2 activity in prostate cancer cells, which allowed E-cadherin re-expression. Introduction of constitutively active MEK6 and MEK1 to DU145 cells cocultured with hepatocytes abrogated E-cadherin re-expression. At least a partial phenotypic reversion can be achieved by suppression of p38 and ERK1/2 activation in DU145 cells even in the absence of hepatocytes. Interestingly, these mitogen-activated protein kinase activities were also triggered by re-expressed E-cadherin leading to p38 and ERK1/2 activity in PCa cells; these signals provide protection to PCa cells upon challenge with chemotherapy and cell death-inducing cytokines. We propose that distinct p38/ERK pathways are related to E-cadherin levels and function downstream of E-cadherin allowing, respectively, for hepatocyte-mediated MErT and tumor cell survival in the face of death signals.

Matrikine and matricellular regulators of EGF receptor signaling on cancer cell migration and invasion

Cancer invasion is a complex process requiring, among other events, extensive remodeling of the extracellular matrix including deposition of pro-migratory and pro-proliferative moieties. In recent years, it has been described that while invading through matrices cancer cells can change shape and adapt their migration strategies depending on the microenvironmental context. Although intracellular signaling pathways governing the mesenchymal to amoeboid migration shift and vice versa have been mostly elucidated, the extracellular signals promoting these shifts are largely unknown. In this review, we summarize findings that point to matrikines that bind specifically to the EGF receptor as matricellular molecules that enable cancer cell migrational plasticity and promote invasion.

A miRNA signature associated with human metastatic medullary thyroid carcinoma

MicroRNAs (miRNAs) represent a class of small, non-coding RNAs that control gene expression by targeting mRNA and triggering either translational repression or RNA degradation. The objective of our study was to evaluate the involvement of miRNAs in human medullary thyroid carcinoma (MTC) and to identify the markers of metastatic cells and aggressive tumour behaviour. Using matched primary and metastatic tumour samples, we identified a subset of miRNAs aberrantly regulated in metastatic MTC. Deregulated miRNAs were confirmed by quantitative real-time PCR and validated by in situ hybridisation on a large independent set of primary and metastatic MTC samples. Our results uncovered ten miRNAs that were significantly expressed and deregulated in metastatic tumours: miR-10a, miR-200b/-200c, miR-7 and miR-29c were down-regulated and miR-130a, miR-138, miR-193a-3p, miR-373 and miR-498 were up-regulated. Bioinformatic approaches revealed potential miRNA targets and signals involved in metastatic MTC pathways. Migration, proliferation and invasion assays were performed in cell lines treated with miR-200 antagomirs to ascertain a direct role for this miRNA in MTC tumourigenesis. We show that the members of miR-200 family regulate the expression of E-cadherin by directly targeting ZEB1 and ZEB2 mRNA and through the enhanced expression of tumour growth factor β (TGFβ)-2 and TGFβ-1. Overall, the treated cells shifted to a mesenchymal phenotype, thereby acquiring an aggressive phenotype with increased motility and invasion. Our data identify a robust miRNA signature associated with metastatic MTC and distinct biological processes, e.g., TGFβ signalling pathway, providing new potential insights into the mechanisms of MTC metastasis.

The Roles of Epithelial-to-Mesenchymal Transition (EMT) and Mesenchymal-to-Epithelial Transition (MET) in Breast Cancer Bone Metastasis: Potential Targets for Prevention and Treatment

Many studies have revealed molecular connections between breast and bone. Genes, important in the control of bone remodeling, such as receptor activator of nuclear kappa (RANK), receptor activator of nuclear kappa ligand (RANKL), vitamin D, bone sialoprotein (BSP), osteopontin (OPN), and calcitonin, are expressed in breast cancer and lactating breast. Epithelial-mesenchymal transition (EMT) and mesenchymal-epithelial transition (MET) effectors play critical roles during embryonic development, postnatal growth, and epithelial homeostasis, but also are involved in a number of pathological conditions, including wound repair, fibrosis, inflammation, as well as cancer progression and bone metastasis. Transforming growth factor β (TGFβ), insulin-like growth factor I & II (IGF I & II), platelet-derived growth factor (PDGF), parathyroid hormone-related protein (PTH(rP)), vascular endothelial growth factor (VEGF), epithelial growth factors II/I (ErbB/EGF), interleukin 6 (IL-6), IL-8, IL-11, IL-1, integrin αvβ3, matrix metalloproteinases (MMPs), catepsin K, hypoxia, notch, Wnt, bone morphogenetic proteins (BMP), and hedgehog signaling pathways are important EMT and MET effectors identified in the bone microenviroment facilitating bone metastasis formation. Recently, Runx2, an essential transcription factor in the regulation of mesenchymal cell differentiation into the osteoblast lineage and proper bone development, is also well-recognized for its expression in breast cancer cells promoting osteolytic bone metastasis. Understanding the precise mechanisms of EMT and MET in the pathogenesis of breast cancer bone metastasis can inform the direction of therapeutic intervention and possibly prevention.

Caught in the act: revealing the metastatic process by live imaging

The prognosis of metastatic cancer in patients is poor. Interfering with metastatic spread is therefore important for achieving better survival from cancer. Metastatic disease is established through a series of steps, including breaching of the basement membrane, intravasation and survival in lymphatic or blood vessels, extravasation, and growth at distant sites. Yet, although we know the steps involved in metastasis, the cellular and molecular mechanisms of dissemination and colonization of distant organs are incompletely understood. Here, we review the important insights into the metastatic process that have been gained specifically through the use of imaging technologies in murine, chicken embryo and zebrafish model systems, including high-resolution two-photon microscopy and bioluminescence. We further discuss how imaging technologies are beginning to allow researchers to address the role of regional activation of specific molecular pathways in the metastatic process. These technologies are shedding light, literally, on almost every step of the metastatic process, particularly with regards to the dynamics and plasticity of the disseminating cancer cells and the active participation of the microenvironment in the processes.

The role of hepatocyte nuclear factor 4alpha in metastatic tumor formation of hepatocellular carcinoma and its close relationship with the mesenchymal-epithelial transition markers

Background

Mesenchymal–epithelial transition (MET) is now suggested to participate in the process of metastatic tumor formation. However, in hepatocellular carcinoma (HCC) the process is still not well revealed.

Methods

Paraffin-embedded tissue samples were obtained from 13 patients with HCC in Shengjing Hospital of China Medical University. The expression of E-cadherin, Fibronectin, N-cadherin, Vimentin, Hepatocyte nuclear factor 4alpha (HNF4alpha), Snail and Slug was assessed in primary tumors and their corresponding metastases by immunohistochemical staining. Next, the expression of HNF4alpha and E-cadherin in four HCC cell lines was examined. Furthermore, SK-Hep-1 cells were transfected with human HNF4alpha expression vector, and the change of E-cadherin expression was assessed.

Results

45.2% (14/31) of the lesions in the metastases showed increased E-cadherin expression compared with the primaries, suggesting the possible occurrence of MET in metastatic tumor formation of HCC, as re-expression of E-cadherin is proposed to be the important hallmark of MET. The occurrence of MET was also confirmed by the reduced expression of Fibronectin (54.8%, 17/31), N-cadherin (38.7%, 12/31) and Vimentin (61.3%, 19/31) in the metastases. 45.2% (14/31) of the lesions in the metastases also showed increased HNF4alpha expression, and 67.7% (21/31) and 48.4% (15/31) of metastases showed decreased Snail and Slug expression respectively. Statistical results showed that the expression of HNF4alpha was positively related with that of E-cadherin, and negatively correlated with that of Snail, Slug and Fibronectin, suggesting that the expression change of the MET markers in the metastatic lesions might be associated with HNF4alpha. Among the four HCC cell lines, both HNF4alpha and E-cadherin expressed high in Hep3B and Huh-7 cells, but low in SK-Hep-1 and Bel-7402 cells. Furthermore, the expression of E-cadherin increased accordingly when SK-Hep-1 cells were transfected with human HNF4alpha expression vector, further confirming the role of HNF4alpha in the regulation of E-cadherin expression.

Conclusions

Our clinical observations and experimental data indicate that HNF4alpha might play a crucial role in the metastatic tumor formation of HCC, and the mechanism may be related with the process of phenotype transition.