Interactions between cancer cells and the endothelium in metastasis

Exosomes Interactions with the Blood-Brain Barrier: Implications for Cerebral Disorders and Therapeutics

The Blood-Brain Barrier (BBB) is a selective structural and functional barrier between the circulatory system and the cerebral environment, playing an essential role in maintaining cerebral homeostasis by limiting the passage of harmful molecules. Exosomes, nanovesicles secreted by virtually all cell types into body fluids, have emerged as a major mediator of intercellular communication. Notably, these vesicles can cross the BBB and regulate its physiological functions. However, the precise molecular mechanisms by which exosomes regulate the BBB remain unclear. Recent research studies focused on the effect of exosomes on the BBB, particularly in the context of their involvement in the onset and progression of various cerebral disorders, including solid and metastatic brain tumors, stroke, neurodegenerative, and neuroinflammatory diseases. This review focuses on discussing and summarizing the current knowledge about the role of exosomes in the physiological and pathological modulation of the BBB. A better understanding of this regulation will improve our understanding of the pathogenesis of cerebral diseases and will enable the design of effective treatment strategies.

Interaction of Drug-Sensitive and -Resistant Human Melanoma Cells with HUVEC Cells: A Label-Free Cell-Based Impedance Study

Cancer cell extravasation is a crucial step in cancer metastasis. However, many of the mechanisms involved in this process are only now being elucidated. Thus, in the present study we analysed the trans-endothelial invasion of melanoma cells by a high throughput label-free cell impedance assay applied to transwell chamber invasion assay. This technique monitors and quantifies in real-time the invasion of endothelial cells by malignant tumour cells, for a long time, avoiding artefacts due to preparation of the end point measurements. Results obtained by impedance analysis were compared with endpoint measurements. In this study, we used human melanoma M14 wild type (WT) cells and their drug resistant counterparts, M14 multidrug resistant (ADR) melanoma cells, selected by prolonged exposure to doxorubicin (DOX). Tumour cells were co-cultured with monolayers of human umbilical vein endothelial cells (HUVEC). Results herein reported demonstrated that: (i) the trans-endothelial migration of resistant melanoma cells was faster than sensitive ones; (ii) the endothelial cells appeared to be strongly affected by the transmigration of melanoma cells which showed the ability to degrade their cytoplasm; (iii) resistant cells preferentially adopted the transcellular invasion vs. the paracellular one; (iv) the endothelial damage mediated by tumour metalloproteinases seemed to be reversible.

Brain metastasis in breast cancer: focus on genes and signaling pathways involved, blood-brain barrier and treatment strategies

Breast cancer (BC) is one of the most prevalent types of cancer in women. Despite advancement in early detection and efficient treatment, recurrence and metastasis continue to pose a significant risk to the life of BC patients. Brain metastasis (BM) reported in 17-20 percent of BC patients is considered as a major cause of mortality and morbidity in these patients. BM includes various steps from primary breast tumor to secondary tumor formation. Various steps involved are primary tumor formation, angiogenesis, invasion, extravasation, and brain colonization. Genes involved in different pathways have been reported to be associated with BC cells metastasizing to the brain. ADAM8 gene, EN1 transcription factor, WNT, and VEGF signaling pathway have been associated with primary breast tumor; MMP1, COX2, XCR4, PI3k/Akt, ERK and MAPK pathways in angiogenesis; Noth, CD44, Zo-1, CEMIP, S0X2 and OLIG2 are involved in invasion, extravasation and colonization, respectively. In addition, the blood-brain barrier is also a key factor in BM. Dysregulation of cell junctions, tumor microenvironment and loss of function of microglia leads to BBB disruption ultimately resulting in BM. Various therapeutic strategies are currently used to control the BM in BC. Oncolytic virus therapy, immune checkpoint inhibitors, mTOR-PI3k inhibitors and immunotherapy have been developed to target various genes involved in BM in BC. In addition, RNA interference (RNAi) and CRISPR/Cas9 are novel interventions in the field of BCBM where research to validate these and clinical trials are being carried out. Gaining a better knowledge of metastasis biology is critical for establishing better treatment methods and attaining long-term therapeutic efficacies against BC. The current review has been compiled with an aim to evaluate the role of various genes and signaling pathways involved in multiple steps of BM in BC. The therapeutic strategies being used currently and the novel ones being explored to control BM in BC have also been discussed at length.

Influence of Exosomes on Astrocytes in the Pre-Metastatic Niche of Lung Cancer Brain Metastases

BACKGROUND

Lung cancer is the most common cause of cancer-related death globally. There are several reasons for this high mortality rate, including metastasis to multiple organs, especially the brain. Exosomes play a pivotal role in tumor metastasis by remodeling the microenvironment of remote target organs and promoting the pre-metastatic niche's formation. Since astrocytes are indispensable for maintaining the homeostasis of brain microenvironment, it's of great interest to explore the influence of lung cancer cell-derived exosomes on astrocytes to further understand the mechanism of lung cancer brain metastasis.

RESULTS

Twenty four h after co-culture of H1299 cell-derived exosomes and SVG P12 cells, the viability of astrocytes decreased and the apoptosis increased. The levels of cytokines in the supernatant including GROα/CXCL1, IFN-γ, IL-3, IL-5, IL-15, LIF, M-CSF, NGF, PDGF, and VEGF were significantly enhanced, while IL-7 secretion was significantly reduced. Meanwhile, apoptosis-related proteins MAP2K1, TUBA1C, RELA, and CASP6 were up-regulated. And the differentially expressed proteins were involved in regulating metabolic pathways.

CONCLUSION

Exosomes of H1299 could induce apoptosis of astrocytes as well as promote their secretion of cytokines that were conducive to the formation of the inflammatory microenvironment and immunosuppressive microenvironment, and affect their metabolic pathways, thus facilitating the formation of pre-metastatic niche in lung cancer brain metastases.

miR-1246 in tumor extracellular vesicles promotes metastasis via increased tumor cell adhesion and endothelial cell barrier destruction

Background

Tumor blood vessels play a key role in tumor metastasis. We have previously reported that tumor endothelial cells (TECs) exhibit abnormalities compared to normal endothelial cells. However, it is unclear how TECs acquire these abnormalities. Tumor cells secrete extracellular vesicles (EVs) to create a suitable environment for themselves. We have previously identified miR-1246 to be more abundant in high metastatic melanoma EVs than in low metastatic melanoma EVs. In the current study, we focused on miR-1246 as primarily responsible for acquiring abnormalities in TECs and examined whether the alteration of endothelial cell (EC) character by miR-1246 promotes cancer metastasis.

Methods

We analyzed the effect of miR-1246 in metastatic melanoma, A375SM-EVs, in vivo metastasis. The role of tumor EV-miR-1246 in the adhesion between ECs and tumor cells and the EC barrier was addressed. Changes in the expression of adhesion molecule and endothelial permeability were examined.

Results

Intravenous administration of A375SM-EVs induced tumor cell colonization in the lung resulting in lung metastasis. In contrast, miR-1246 knockdown in A375SM decreased lung metastasis in vivo. miR-1246 transfection in ECs increased the expression of adhesion molecule ICAM-1 via activation of STAT3, followed by increased tumor cell adhesion to ECs. Furthermore, the expression of VE-Cadherin was downregulated in miR-1246 overexpressed EC. A375SM-EV treatment enhanced endothelial permeability. VE-Cadherin was validated as the potential target gene of miR-1246 via the target gene prediction database and 3' UTR assay.

Conclusion

miR-1246 in high metastatic tumor EVs promotes lung metastasis by inducing the adhesion of tumor cells to ECs and destroying the EC barrier.

Interacting with tumor cells weakens the intrinsic clockwise chirality of endothelial cells

Endothelial cells (ECs) possess a strong intrinsic clockwise (CW, or rightward) chirality under normal conditions. Enervating this chirality of ECs significantly impairs the function of the endothelial barrier. Malignant tumor cells (TCs) undergo metastasis by playing upon the abnormal leakage of blood vessels. However, the impact of TCs on EC chirality is still poorly understood. Using a transwell model, we co-cultured the human umbilical vein endothelial cells or human lung microvascular endothelial cells and breast epithelial tumor cell lines to simulate the TC-EC interaction. Using a micropatterning method, we assessed the EC chirality changes induced by paracrine signaling of and physical contact with TCs. We found that the intrinsic clockwise chirality of ECs was significantly compromised by the TC's physical contact, while the paracrine signaling (i.e., without physical contact) of TCs causes minimal changes. In addition, ECs neighboring TCs tend to possess a left bias, while ECs spaced apart from TCs are more likely to preserve the intrinsic right bias. Finally, we found the chirality change of ECs could result from physical binding between CD44 and E-selectin, which activates protein kinase C alpha (PKCα) and induces pseudopodial movement of EC toward TC. Our findings together suggest the crucial role of EC-TC physical interaction in EC chirality and that weakening the EC chirality could potentially compromise the overall endothelial integrity which increases the probability of metastatic cancer spread.

The Role of MiR-181 Family Members in Endothelial Cell Dysfunction and Tumor Angiogenesis

Endothelial dysfunction plays a critical role in many human angiogenesis-related diseases, including cancer and retinopathies. Small non-coding microRNAs (miRNAs) repress gene expression at the post-transcriptional level. They are critical for endothelial cell gene expression and function and are involved in many pathophysiological processes. The miR-181 family is one of the essential angiogenic regulators. This review summarizes the current state of knowledge of the role of miR-181 family members in endothelial cell dysfunction, with emphasis on their pathophysiological roles in aberrant angiogenesis. The actions of miR-181 members are summarized concerning their targets and associated major angiogenic signaling pathways in a cancer-specific context. Elucidating the underlying functional mechanisms of miR-181 family members that are dysregulated in endothelial cells or cancer cells is invaluable for developing miRNA-based therapeutics for angiogenesis-related diseases such as retinopathies, angiogenic tumors, and cancer. Finally, potential clinical applications of miR-181 family members in anti-angiogenic tumor therapy are discussed.

Selective histone methyltransferase G9a inhibition reduces metastatic development of Ewing sarcoma through the epigenetic regulation of NEU1

Ewing sarcoma (EWS) is an aggressive bone and soft tissue tumor with high susceptibility to metastasize. The underlying molecular mechanisms leading to EWS metastases remain poorly understood. Epigenetic changes have been implicated in EWS tumor growth and progression. Linking epigenetics and metastases may provide insight into novel molecular targets in EWS and improve its treatment. Here, we evaluated the effects of a selective G9a histone methyltransferase inhibitor (BIX01294) on EWS metastatic process. Our results showed that overexpression of G9a in tumors from EWS patients correlates with poor prognosis. Moreover, we observe a significantly higher expression of G9a in metastatic EWS tumor as compared to either primary or recurrent tumor. Using functional assays, we demonstrate that pharmacological G9a inhibition using BIX01294 disrupts several metastatic steps in vitro, such as migration, invasion, adhesion, colony formation and vasculogenic mimicry. Moreover, BIX01294 reduces tumor growth and metastases in two spontaneous metastases mouse models. We further identified the sialidase NEU1 as a direct target and effector of G9a in the metastatic process in EWS. NEU1 overexpression impairs migration, invasion and clonogenic capacity of EWS cell lines. Overall, G9a inhibition impairs metastases in vitro and in vivo through the overexpression of NEU1. G9a has strong potential as a prognostic marker and may be a promising therapeutic target for EWS patients.

A Pillar-Free Diffusion Device for Studying Chemotaxis on Supported Lipid Bilayers

Chemotactic cell migration plays a crucial role in physiological and pathophysiological processes. In tissues, cells can migrate not only through extracellular matrix (ECM), but also along stromal cell surfaces via membrane-bound receptor–ligand interactions to fulfill critical functions. However, there remains a lack of models recapitulating chemotactic migration mediated through membrane-bound interactions. Here, using micro-milling, we engineered a multichannel diffusion device that incorporates a chemoattractant gradient and a supported lipid bilayer (SLB) tethered with membrane-bound factors that mimics stromal cell membranes. The chemoattractant channels are separated by hydrogel barriers from SLB in the cell loading channel, which enable precise control of timing and profile of the chemokine gradients applied on cells interacting with SLB. The hydrogel barriers are formed in pillar-free channels through a liquid pinning process, which eliminates complex cleanroom-based fabrications and distortion of chemoattractant gradient by pillars in typical microfluidic hydrogel barrier designs. As a proof-of-concept, we formed an SLB tethered with ICAM-1, and demonstrated its lateral mobility and different migratory behavior of Jurkat T cells on it from those on immobilized ICAM-1, under a gradient of chemokine CXCL12. Our platform can thus be widely used to investigate membrane-bound chemotaxis such as in cancer, immune, and stem cells.

An unusual nicotinamide derivative, 4-pyridone-3-carboxamide ribonucleoside (4PYR), is a novel endothelial toxin and oncometabolite

Our recent studies identified a novel pathway of nicotinamide metabolism that involves 4-pyridone-3-carboxamide-1-β-D-ribonucleoside (4PYR) and demonstrated its endothelial cytotoxic effect. This study tested the effects of 4PYR and its metabolites in experimental models of breast cancer. Mice were divided into groups: 4T1 (injected with mammary 4T1 cancer cells), 4T1 + 4PYR (4PYR-treated 4T1 mice), and control, maintained for 2 or 21 days. Lung metastasis and endothelial function were analyzed together with blood nucleotides (including 4PYR), plasma amino acids, nicotinamide metabolites, and vascular ectoenzymes of nucleotide catabolism. 4PYR metabolism was also evaluated in cultured 4T1, MDA-MB-231, MCF-7, and T47D cells. An increase in blood 4PYR in 4T1 mice was observed at 2 days. 4PYR and its metabolites were noticed after 21 days in 4T1 only. Higher blood 4PYR was linked with more lung metastases in 4T1 + 4PYR vs. 4T1. Decreased L-arginine, higher asymmetric dimethyl-L-arginine, and higher vascular ecto-adenosine deaminase were observed in 4T1 + 4PYR vs. 4T1 and control. Vascular relaxation caused by flow-dependent endothelial activation in 4PYR-treated mice was significantly lower than in control. The permeability of 4PYR-treated endothelial cells was increased. Decreased nicotinamide but enhanced nicotinamide metabolites were noticed in 4T1 vs. control. Reduced N-methylnicotinamide and a further increase in Met2PY were observed in 4T1 + 4PYR vs. 4T1 and control. In cultured breast cancer cells, estrogen and progesterone receptor antagonists inhibited the production of 4PYR metabolites. 4PYR formation is accelerated in cancer and induces metabolic disturbances that may affect cancer progression and, especially, metastasis, probably through impaired endothelial homeostasis. 4PYR may be considered a new oncometabolite.

Levels of a metabolite of nicotinamide, a form of vitamin B₃, found in the blood and urine of cancer patients may provide a useful biomarker indicating the likelihood of metastasis. Disruption to the lining of blood vessels (endothelium) enables cancer cells to infiltrate the bloodstream and migrate to other organs. Research suggests that increased levels of 4PYR, a derivative of nicotinamide metabolism, may induce metabolic disturbances that favor cancer progression. Ewa Slominska and co-workers at the Medical University of Gdansk, Poland, examined 4PYR in mouse models injected with breast cancer cells and found increased levels in the blood only two days after injection. Mice with the highest 4PYR levels had enhanced lung metastases after three weeks. The team believes 4PYR activity may increase the permeability of the endothelium, but further investigation is needed.

Directed movement toward, translocation along, penetration into and exit from vascular networks by breast cancer cells in 3D

We developed a computer-assisted platform using laser scanning confocal microscopy to 3D reconstruct in real-time interactions between metastatic breast cancer cells and human umbilical vein endothelial cells (HUVECs). We demonstrate that MB-231 cancer cells migrate toward HUVEC networks, facilitated by filopodia, migrate along the network surfaces, penetrate into and migrate within the HUVEC networks, exit and continue migrating along network surfaces. The system is highly amenable to 3D reconstruction and computational analyses, and assessments of the effects of potential anti-metastasis monoclonal antibodies and other drugs. We demonstrate that an anti-RHAMM antibody blocks filopodium formation and all of the behaviors that we found take place between MB-231 cells and HUVEC networks.

B16 Melanoma Cancer Cells with Higher Metastatic Potential are More Deformable at a Whole-Cell Level

INTRODUCTION

Metastasis is a process in which cancer cells spread from the primary focus site to various other organ sites. Many studies have suggested that reduced stiffness would facilitate passing through extracellular matrix when cancer cells instigate a metastatic process. Here we investigated the compressive properties of melanoma cancer cells with different metastatic potentials at the whole-cell level. Differences in their compressive properties were analyzed by examining actin filament structure and actin-related gene expression.

METHODS

Compressive tests were carried out for two metastatic B16 melanoma variants (B16-F1 and B16-F10) to characterize global compressive properties of cancer cells. RNA-seq analysis and fluorescence microscopic imaging were performed to clarify contribution of actin filaments to the global compressive properties.

RESULTS

RNA-seq analysis and fluorescence microscopic imaging revealed the undeveloped structure of actin filaments in B16-F10 cells. The Young's modulus of B16-F10 cells was significantly lower than that of B16-F1 cells. Disruption of the actin filaments in B16-F1 cells reduced the Young's modulus to the same level as that of B16-F10 cells, while the Young's modulus in B16-F10 cells remained the same regardless of the disruption.

CONCLUSIONS

In B16 melanoma cancer cell lines, cells with higher metastatic potential were more deformable at the whole-cell level with undeveloped actin filament structure, even when highly deformed. These results imply that invasive cancer cells may gain the ability to inhibit actin filament development.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at (10.1007/s12195-021-00677-w).

The driving role of the Cdk5/Tln1/FAKS732 axis in cancer cell extravasation dissected by human vascularized microfluidic models

BACKGROUND

Understanding the molecular mechanisms of metastatic dissemination, the leading cause of death in cancer patients, is required to develop novel, effective therapies. Extravasation, an essential rate-limiting process in the metastatic cascade, includes three tightly coordinated steps: cancer cell adhesion to the endothelium, trans-endothelial migration, and early invasion into the secondary site. Focal adhesion proteins, including Tln1 and FAK, regulate the cytoskeleton dynamics: dysregulation of these proteins is often associated with metastatic progression and poor prognosis.

METHODS

Here, we studied the previously unexplored role of these targets in each extravasation step using engineered 3D in vitro models, which recapitulate the physiological vascular niche experienced by cancer cells during hematogenous metastasis.

RESULTS

Human breast cancer and fibrosarcoma cell lines respond to Cdk5/Tln1/FAK axis perturbation, impairing their metastatic potential. Vascular breaching requires actin polymerization-dependent invadopodia formation. Invadopodia generation requires the structural function of FAK and Tln1 rather than their activation through phosphorylation. Our data support that the inhibition of FAKS732 phosphorylation delocalizes ERK from the nucleus, decreasing ERK phosphorylated form. These findings indicate the critical role of these proteins in driving trans-endothelial migration. In fact, both knock-down experiments and chemical inhibition of FAK dramatically reduces lung colonization in vivo and TEM in microfluidic setting. Altogether, these data indicate that engineered 3D in vitro models coupled to in vivo models, genetic, biochemical, and imaging tools represent a powerful weapon to increase our understanding of metastatic progression.

CONCLUSIONS

These findings point to the need for further analyses of previously overlooked phosphorylation sites of FAK, such as the serine 732, and foster the development of new effective antimetastatic treatments targeting late events of the metastatic cascade.

Systemic metastasis-targeted nanotherapeutic reinforces tumor surgical resection and chemotherapy

Failure of conventional clinical therapies such as tumor resection and chemotherapy are mainly due to the ineffective control of tumor metastasis. Metastasis consists of three steps: (i) tumor cells extravasate from the primary sites into the circulation system via epithelial-mesenchymal transition (EMT), (ii) the circulating tumor cells (CTCs) form “micro-thrombi” with platelets to evade the immune surveillance in circulation, and (iii) the CTCs colonize in the pre-metastatic niche. Here, we design a systemic metastasis-targeted nanotherapeutic (H@CaPP) composed of an anti-inflammatory agent, piceatannol, and an anti-thrombotic agent, low molecular weight heparin, to hinder the multiple steps of tumor metastasis. H@CaPP is found efficiently impeded EMT, inhibited the formation of “micro-thrombi”, and prevented the development of pre-metastatic niche. When combined with surgical resection or chemotherapy, H@CaPP efficiently inhibits tumor metastasis and prolonged overall survival of tumor-bearing mice. Collectively, we provide a simple and effective systemic metastasis-targeted nanotherapeutic for combating tumor metastasis.

Failure of conventional clinical therapies such as tumor resection and chemotherapy are mainly due to the ineffective control of tumor metastasis. Here, the authors show that a systemic metastasis-targeted nanotherapeutic may offer a powerful adjunct therapy for suppressing tumor metastasis.

Inhibition of cell migration and invasion by ICAM-1 binding DNA aptamers

Cancer is the second leading cause of death worldwide and most of the cancer-related deaths result from metastasis. As expressed on the surface of various cancer cell types, intercellular adhesion molecule-1 (ICAM-1) has been shown to play a role in the attachment, invasion and migration of tumor cells. In this study, DNA aptamers were generated against ICAM-1 by cell-SELEX and protein SELEX method using ICAM-1⁽⁺⁾ CHO-ICAM-1 cells and ICAM-1 protein, respectively. The pools obtained at the end of the 10th round of both SELEX were sequenced and the most enriched sequences were characterized for their binding behaviors and affinities to ICAM-1⁽⁺⁾ CHO-ICAM-1 and ICAM-1^(-) MIA PaCa-2 cells. Moreover, the inhibition abilities of sequences on migration and invasion were measured. The seven aptamer sequences were obtained selectively binding to CHO-ICAM-1 cells with K_d values in the ranging from 13.8 to 47.1 nM. Four of these aptamers showed inhibition in both migration and invasion of CHO-ICAM-1 cells at least 61%. All these results suggested that these aptamers have potential to detect specifically ICAM-1 expressing tumor cells and inhibit migration and invasion by blocking ICAM-1 related interactions of circulating tumor cells.

Frugal Approach toward Developing a Biomimetic, Microfluidic Network-on-a-Chip for In Vitro Analysis of Microvascular Physiology

Several disease conditions, such as cancer metastasis and atherosclerosis, are deeply connected with the complex biophysical phenomena taking place in the complicated architecture of the tiny blood vessels in human circulatory systems. Traditionally, these diseases have been probed by devising various animal models, which are otherwise constrained by ethical considerations as well as limited predictive capabilities. Development of an engineered network-on-a-chip, which replicates not only the functional aspects of the blood-carrying microvessels of human bodies, but also its geometrical complexity and hierarchical microstructure, is therefore central to the evaluation of organ-assist devices and disease models for therapeutic assessment. Overcoming the constraints of reported resource-intensive fabrication techniques, here, we report a facile, simple yet niche combination of surface engineering and microfabrication strategy to devise a highly ordered hierarchical microtubular network embedded within a polydimethylsiloxane (PDMS) slab for dynamic cell culture on a chip, with a vision of addressing the exclusive aspects of the vascular transport processes under medically relevant paradigms. The design consists of hierarchical complexity ranging from capillaries (∼80 μm) to large arteries (∼390 μm) and a simultaneous tuning of the interfacial material chemistry. The fluid flow behavior is characterized numerically within the hierarchical network, and a confluent endothelial layer is realized on the inner wall of microfluidic device. We further explore the efficacy of the device as a vascular deposition assay of circulatory tumor cells (MG-63 osteosarcoma cells) present in whole blood. The proposed paradigm of mimicking an in vitro vascular network in a low-cost paradigm holds further potential for probing cellular dynamics as well as offering critical insights into various vascular transport processes.

Oral exposure to BDE-209 modulates metastatic spread of melanoma in C57BL/6 mice inoculated with B16-F10 cells

Polybrominated diphenyl ethers (PBDEs) are brominated, persistent and bioaccumulative flame retardants widely used in the manufacture of plastic products. Decabromodiphenyl ether (BDE-209) is the most prevalent PBDE in the atmosphere and found in human blood, breast milk and umbilical cord. In vitro studies showed that BDE-209 interferes with murine melanoma cells (B16F10), modulating cell death rates, proliferation and migration, important events for cancer progression. In order to evaluate if BDE-209 modulates metastasis formation in murine models, C57BL/6 mice were exposed to BDE-209 (0.08, 0.8 and 8 μg⁄kg) via gavage (5-day intervals for 45 days) (9 doses in total). Then, mice were inoculated with melanoma cells (B16-F10) at caudal vein receiving 4 additional doses of BDE-209. At 20th day post-cell inoculation, blood, lung, liver, kidney and brain were sampled for hematological, biochemical and morphological analyses. The slightly higher levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in the blood and pro-oxidant state in the liver of BDE-exposed mice indicated liver damage. Although the in vivo approach is for metastasis formation in the lung, they were unexpectedly observed in non-target organs (liver, brain, kidney and gonads). The similarity test showed high proximity among individuals from the control and a dissimilarity index between the control and exposed groups. The present data corroborate the known hepatotoxicity of BDE-209 to mice (C57BL/6) and demonstrate for the first time the increase of metastatic dissemination of B16F10 cells in vivo due to previous and continuous BDE-209 exposure, revealing possible implications of this organic compound with melanoma malignancy related traits.

A practical toolkit to study aspects of the metastatic cascade in vitro

While metastasis - the spread of cancer from the primary location to distant sites in the body - remains the principle cause of cancer death, it is incompletely understood. It is a complex process, requiring the metastatically successful cancer cell to negotiate a formidable series of interconnected steps, which are described in this paper. For each step, we review the range of in vitro assays that may be used to study them. We also provide a range of detailed, step-by-step protocols that can be undertaken in most modestly-equipped laboratories, including methods for converting qualitative observations into quantitative data for analysis. Assays include: (1) a gelatin degradation assay to study the ability of endothelial cells to degrade extracellular matrix during tumour angiogenesis; (2) the morphological characterisation of cells undergoing epithelial-mesenchymal transition (EMT) as they acquire motility; (3) a 'scratch' or 'wound-healing' assay to study cancer cell migration; (4) a transwell assay to study cancer cell invasion through extracellular matrix; and (5) a static adhesion assay to examine cancer cell interactions with, and adhesion to, endothelial monolayers. This toolkit of protocols will enable researchers who are interested in metastasis to begin to focus on defined aspects of the process. It is only by further understanding this complex, fascinating and clinically relevant series of events that we may ultimately devise ways of better treating, or even preventing, cancer metastasis. The assays may also be of more broad interest to researchers interested in studying aspects of cellular behaviour in relation to other developmental and disease processes.

Site-specific metastasis: A cooperation between cancer cells and the metastatic microenvironment

The conclusion derived from the information provided in this review is that disseminating tumor cells (DTC) collaborate with the microenvironment of a future metastatic organ site in the establishment of organ‐specific metastasis. We review the basic principles of site‐specific metastasis and the contribution of the cross talk between DTC and the microenvironment of metastatic sites (metastatic microenvironment [MME]) to the establishment of the organ‐specific premetastatic niche; the targeted migration of DTC to the endothelium of the future organ‐specific metastasis; the transmigration of DTC to this site and the seeding and colonization of DTC in their future MME. We also discuss the role played by DTC‐MME interactions on tumor dormancy and on the differential response of tumor cells residing in different MMEs to antitumor therapy. Finally, we summarize some studies dealing with the effects of the MME on a unique site‐specific metastasis—brain metastasis.

Melanoma in the liver: Oxidative stress and the mechanisms of metastatic cell survival

Metastatic melanoma is a fatal disease with a rapid systemic dissemination. The most frequent target sites are the liver, bone, and brain. Melanoma metastases represent a heterogeneous cell population, which associates with genomic instability and resistance to therapy. Interaction of melanoma cells with the hepatic sinusoidal endothelium initiates a signaling cascade involving cytokines, growth factors, bioactive lipids, and reactive oxygen and nitrogen species produced by the cancer cell, the endothelium, and also by different immune cells. Endothelial cell-derived NO and H₂O₂ and the action of immune cells cause the death of most melanoma cells that reach the hepatic microvascularization. Surviving melanoma cells attached to the endothelium of pre-capillary arterioles or sinusoids may follow two mechanisms of extravasation: a) migration through vessel fenestrae or b) intravascular proliferation followed by vessel rupture and microinflammation. Invading melanoma cells first form micrometastases within the normal lobular hepatic architecture via a mechanism regulated by cross-talk with the stroma and multiple microenvironment-related molecular signals. In this review special emphasis is placed on neuroendocrine (systemic) mechanisms as potential promoters of liver metastatic growth. Growing metastatic cells undergo functional and metabolic changes that increase their capacity to withstand oxidative/nitrosative stress, which favors their survival. This adaptive process also involves upregulation of Bcl-2-related antideath mechanisms, which seems to lead to the generation of more resistant cell subclones.

Phosphatidylserine-exposing blood cells, microparticles and neutrophil extracellular traps increase procoagulant activity in patients with pancreatic cancer

Patients with pancreatic cancer (PC) are at increased risk of venous thrombosis, but the precise mechanisms of hypercoagulable state in PC remain unclear. We aimed to identify how phosphatidylserine positive (PS⁺) blood cells (BCs), PS⁺ microparticles (MPs) and neutrophil extracellular traps (NETs) regulate procoagulant activity (PCA) in PC, and to assess the relationship between PCA and PC staging. A total of 83 PC patients with different stages of disease were compared to 30 healthy controls, with confocal microscopy and flow cytometry used to assess MP and cellular PS exposure. MP and cell PCA was determined using both fibrin production assays and procoagulant enzyme complex analyses, and coagulation time was further measured. Patients with stage I PC and healthy controls exhibited significantly lower frequencies of PS⁺ MPs and BCs relative to those with more advanced disease, which may partly due to the increased levels of inflammation cytokines in advanced disease. Functional coagulation assays indicated that PS⁺ MPs and BCs derived from patients with stage II/III/IV PC directly contribute to elevated FXa, thrombin, and fibrin formation, and to more rapid coagulation relative to healthy control samples. In inhibition assays, lactadherin, which antagonizes PS, led to a roughly 80% inhibition of PCA. We further used isolated NETs to stimulate endothelial cells, revealing that this led to morphological changes including retraction from cell-cell junctions and a more pro-coagulative phenotype, with DNase I and activated protein C treatment reversing these changes. In patients with stage III PC, curative resection surgery significantly reduced PCA, whereas non-curative surgery did not have a marked impact based on studies of pre- and post-operative samples. These results highlight the pathogenic activity of PS⁺ cells, MPs, and NETs in promoting a prothrombotic environment within individuals suffering from advanced PC. Targeting PS and NETs in these patients may thus be a viable means of preventing pathological thrombosis.

Metformin and Docosahexaenoic Acid Hybrid Micelles for Premetastatic Niche Modulation and Tumor Metastasis Suppression

Metastasis is the major cause of high mortality in cancer patients; thus, blocking the metastatic process is of critical importance for cancer treatments. The premetastatic niche, a specialized microenvironment with aberrant changes related to inflammation, allows the colonization of circulating tumor cells (CTCs) and serves as a potential target for metastasis prevention. However, little effort has been dedicated to developing nanomedicine to amend the premetastatic niche. Here this study reports a premetastatic niche-targeting micelle for the modulation of premetastatic microenvironments and suppression of tumor metastasis. The micelles are self-assembled with the oleate carbon chain derivative of metformin and docosahexaenoic acid, two anti-inflammatory agents with low toxicity, and coated with fucoidan for premetastatic niche-targeting. The obtained functionalized micelles (FucOMDs) exhibit an excellent blood circulation profile and premetastatic site-targeting efficiency, inhibit CTC adhesion to activated endothelial cells, alleviate lung vascular permeability, and reverse the aberrant expression of key marker proteins in premetastatic niches. As a result, FucOMDs prevent metastasis formation and efficiently suppress both primary-tumor growth and metastasis formation when combined with targeted chemotherapy. Collectively, the findings here provide proof of concept that the modulation of the premetastatic niche with targeted anti-inflammatory agents provides a potent platform and a safe and clinical translational option for the suppression of tumor metastasis.

Elevated serum levels of sialyl Lewis X (sLeX) and inflammatory mediators in patients with breast cancer

PURPOSE

The carbohydrate sialyl Lewis^X (sLe^X) mediates cell adhesion, is critical in the normal function of immune cells, and is frequently over-expressed on cancer cells. We assessed the association, differential levels, and prognostic value of sLe^X and inflammatory cytokines/chemokines in breast cancer sera.

METHODS

We retrospectively measured sLe^X and a panel of cytokines/chemokines in the sera of 26 non-invasive ductal carcinoma in situ (DCIS), 154 invasive non-metastatic breast cancer (non-MBC), 63 metastatic breast cancer (MBC) patients, and 43 healthy controls. Differences in sLe^X and inflammatory cytokines among and between patient groups and healthy controls were assessed with nonparametric tests and we performed survival analysis for the prognostic potential of sLe^X using a cut-off of 8 U/mL as previously defined.

RESULTS

Median serum sLe^X was significantly higher than controls for invasive breast cancer patients (MBC and non-MBC) but not DCIS. In univariate analysis, we confirmed patients with serum sLe^X > 8 U/mL have a significantly shorter progression-free survival (PFS) (P = 0.0074) and overall survival (OS (P = 0.0003). Similarly, patients with high serum MCP-1 and IP-10 had shorter OS (P = 0.001 and P < 0.001, respectively) and PFS (P = 0.010 and P < 0.001, respectively). sLe^X, MCP-1 and IP-10 remained significant in multivariate survival analysis.

CONCLUSION

Elevated serum sLe^X was associated with invasive cancer but not DCIS. High serum sLe^X levels were associated with inflammatory mediators and may play a role in facilitating local invasion of breast tumor. Furthermore, serum MCP-1, IP-10 and sLe^X may have prognostic value in breast cancer.

Mechanically stimulated osteocytes reduce the bone-metastatic potential of breast cancer cells in vitro by signaling through endothelial cells

Bone metastases occur in 65% to 75% of patients with advanced breast cancer and significantly worsen their survival and quality of life. We previously showed that conditioned medium (CM) from osteocytes stimulated with oscillatory fluid flow, mimicking bone mechanical loading during routine physical activities, reduced the transendothelial migration of breast cancer cells. Endothelial cells are situated at an ideal location to mediate signals between osteocytes in the bone matrix and metastasizing cancer cells in the blood vessels. In this study, we investigated the specific effects of flow-stimulated osteocytes on the interaction between endothelial cells and breast cancer cells in vitro. We observed that CM from flow-stimulated osteocytes reduced endothelial permeability by 15% and breast cancer cell adhesion onto endothelial monolayers by 18%. The difference in adhesion was abolished with anti-intercellular adhesion molecule 1 (ICAM-1) neutralizing antibodies. Furthermore, CM from endothelial cells conditioned in CM from flow-stimulated osteocytes significantly altered the gene expression in bone-metastatic breast cancer cells, as shown by RNA sequencing. Specifically, breast cancer cell expression of matrix metallopeptidase 9 (MMP-9) was downregulated by 62%, and frizzled-4 (FZD4) by 61%, when the osteocytes were stimulated with flow. The invasion of these breast cancer cells across Matrigel was also reduced by 47%, and this difference was abolished by MMP-9 inhibitors. In conclusion, we demonstrated that flow-stimulated osteocytes downregulate the bone-metastatic potential of breast cancer cells by signaling through endothelial cells. This provides insights into the capability of bone mechanical regulation in preventing bone metastases; and may assist in prescribing exercise or bone-loading regimens to patients with breast cancers.

Mechanophenotyping of B16 Melanoma Cell Variants for the Assessment of the Efficacy of (-)-Epigallocatechin Gallate Treatment Using a Tapered Microfluidic Device

Metastatic cancer cells are known to have a smaller cell stiffness than healthy cells because the small stiffness is beneficial for passing through the extracellular matrix when the cancer cells instigate a metastatic process. Here we developed a simple and handy microfluidic system to assess metastatic capacity of the cancer cells from a mechanical point of view. A tapered microchannel was devised through which a cell was compressed while passing. Two metastasis B16 melanoma variants (B16-F1 and B16-F10) were examined. The shape recovery process of the cell from a compressed state was evaluated with the Kelvin⁻Voigt model. The results demonstrated that the B16-F10 cells showed a larger time constant of shape recovery than B16-F1 cells, although no significant difference in the initial strain was observed between B16-F1 cells and B16-F10 cells. We further investigated effects of catechin on the cell deformability and found that the deformability of B16-F10 cells was significantly decreased and became equivalent to that of untreated B16-F1 cells. These results addressed the utility of the present system to handily but roughly assess the metastatic capacity of cancer cells and to investigate drug efficacy on the metastatic capacity.

The pretubulysin-induced exposure of collagen is caused by endothelial cell retraction that results in an increased adhesion and decreased transmigration of tumor cells

Microtubule-targeting agents (MTAs) are the most widely used chemotherapeutic drugs. Pretubulysin (PT), a biosynthetic precursor of the myxobacterial tubulysins, was recently identified as a novel MTA. Besides its strong anti-tumoral activities, PT attenuates tumor angiogenesis, exerts anti-vascular actions on tumor vessels and decreases cancer metastasis formation in vivo. The aim of the present study was to analyze the impact of PT on the interaction of endothelial and tumor cells in vitro to gain insights into the mechanism underlying its anti-metastatic effect. The influence of PT on tumor cell adhesion and transmigration onto/through the endothelium as well as its influence on cell adhesion molecules and the chemokine system CXCL12/CXCR4 was investigated. Treatment of human endothelial cells with PT increased the adhesion of breast cancer cells to the endothelial monolayer, whereas their transmigration through the endothelium was strongly reduced. Interestingly, the PT-induced upregulation of ICAM-1, VCAM-1 and CXCL12 were dispensable for the PT-evoked tumor cell adhesion. Tumor cells preferred to adhere to collagen exposed within PT-triggered endothelial gaps via β1-integrins on the tumor cell surface. Taken together, our study provides, at least in part, an explanation for the anti-metastatic potential of PT.

Polyphenolic Nutrients in Cancer Chemoprevention and Metastasis: Role of the Epithelial-to-Mesenchymal (EMT) Pathway

The epithelial-to-mesenchymal transition (EMT) has received significant interest as a novel target in cancer prevention, metastasis, and resistance. The conversion of cells from an epithelial, adhesive state to a mesenchymal, motile state is one of the key events in the development of cancer metastasis. Polyphenols have been reported to be efficacious in the prevention of cancer and reversing cancer progression. Recently, the antimetastatic efficacy of polyphenols has been reported, thereby expanding the potential use of these compounds beyond chemoprevention. Polyphenols may affect EMT pathways, which are involved in cancer metastasis; for example, polyphenols increase the levels of epithelial markers, but downregulate the mesenchymal markers. Polyphenols also alter the level of expression and functionality of important proteins in other signaling pathways that control cellular mesenchymal characteristics. However, the specific proteins that are directly affected by polyphenols in these signaling pathways remain to be elucidated. The aim of this review is to analyze current evidence regarding the role of polyphenols in attenuating EMT-mediated cancer progression and metastasis. We also discuss the role of the most important polyphenol subclasses and members of the polyphenols in reversing metastasis and targeting EMT. Finally, limitations and future directions to improve our understanding in this field are discussed.

Dual Role of the Extracellular Domain of Human Mucin MUC1 in Metastasis

Human mucin MUC1 plays an important role in cancer development. The increased level of this molecule expression during cancer cell progression induces metastasis and is associated with poor prognosis for patients. There is a large body of experimental data on the role of various functional domains of human mucin MUC1 in metastasis. While, the cytoplasmic domain determined to play a definitive role, the influence of extracellular domain on cancer cell invasiveness still remains unclear. The present paper reveals that the extracellular domain of MUC1 molecule consists of two functional subdomains-the region of tandem repeats (TR) and the region of irregular repeats (IR). We demonstrate the ability of each of these subdomains to alter the invasiveness of cancer cells. The presence of the MUC1 molecules containing TR subdomain (MUC1-TR) on the surface of low-invasive cancer cells leads to the increase in their transendothelial migration potency, while the addition of the IR subdomain to the MUC1-TR molecule (MUC1-IR-TR) restores their natural low invasiveness. J. Cell. Biochem. 118: 4002-4011, 2017. © 2017 Wiley Periodicals, Inc.

CD44-mediated activation of α5β1-integrin, cortactin and paxillin signaling underpins adhesion of basal-like breast cancer cells to endothelium and fibronectin-enriched matrices

CD44 expression is elevated in basal-like breast cancer (BLBC) tissue, and correlates with increased efficiency of distant metastasis in patients and experimental models. We sought to characterize mechanisms underpinning CD44-promoted adhesion of BLBC cells to vascular endothelial monolayers and extracellular matrix (ECM) substrates. Stimulation with hyaluronan (HA), the native ligand for CD44, increased expression and activation of β1-integrin receptors, and increased α5-integrin subunit expression. Adhesion assays confirmed that CD44-signalling potentiated BLBC cell adhesion to endothelium and Fibronectin in an α5B1-integrin-dependent mechanism. Co-immunoprecipitation experiments confirmed HA-promoted association of CD44 with talin and the β1-integrin chain in BLBC cells. Knockdown of talin inhibited CD44 complexing with β1-integrin and repressed HA-induced, CD44-mediated activation of β1-integrin receptors. Immunoblotting confirmed that HA induced rapid phosphorylation of cortactin and paxillin, through a CD44-dependent and β1-integrin-dependent mechanism. Knockdown of CD44, cortactin or paxillin independently attenuated the adhesion of BL-BCa cells to endothelial monolayers and Fibronectin. Accordingly, we conclude that CD44 induced, integrin-mediated signaling not only underpins efficient adhesion of BLBC cells to BMECs to facilitate extravasation but initiates their adhesion to Fibronectin, enabling penetrant cancer cells to adhere more efficiently to underlying Fibronectin-enriched matrix present within the metastatic niche.

3D microvascular model recapitulates the diffuse large B-cell lymphoma tumor microenvironment in vitro

Diffuse large B-cell lymphoma (DLBCL) is an aggressive cancer that affects ∼22 000 people in the United States yearly. Understanding the complex cellular interactions of the tumor microenvironment is critical to the success and development of DLBCL treatment strategies. In vitro platforms that successfully model the complex tumor microenvironment without introducing the variability of in vivo systems are vital for understanding these interactions. To date, no such in vitro model exists that can accurately recapitulate the interactions that occur between immune cells, cancer cells, and endothelial cells in the tumor microenvironment of DLBCL. To that end, we developed a lymphoma-on-chip model consisting of a hydrogel based tumor model traversed by a vascularized, perfusable, round microchannel that successfully recapitulates key complexities and interactions of the in vivo tumor microenvironment in vitro. We have shown that the perfusion capabilities of this technique allow us to study targeted treatment strategies, as well as to model the diffusion of infused reagents spatiotemporally. Furthermore, this model employs a novel fabrication technique that utilizes common laboratory materials, and allows for the microfabrication of multiplex microvascular environments without the need for advanced microfabrication facilities. Through our facile microfabrication process, we are able to achieve micro vessels within a tumor model that are highly reliable and precise over the length of the vessel. Overall, we have developed a tool that enables researchers from many diverse disciplines to study previously inaccessible aspects of the DLBCL tumor microenvironment, with profound implications for drug delivery and design.

Knockdown of ezrin suppresses the migration and angiogenesis of human umbilical vein endothelial cells in vitro

Progressive tumor growth is dependent on angiogenesis. The mechanisms by which endothelial cells (ECs) are incorporated to develop new blood vessels are not well understood. Recent studies reveal that the ezrin radixin moesin (ERM) family members are key regulators of cellular activities such as adhesion, morphogenetic change, and migration. We hypothesized that ezrin, one of the ERM family members, may play important roles in ECs organization during angiogenesis, and new vessels formation in preexisting tissues. To test this hypothesis, in this study, we investigated the effects of ezrin gene silencing on the migration and angiogenesis of human umbilical vein endothelial cells (HUVECs) in vitro. HUVECs were transfected with plasmids with ezrin-targeting short hairpin RNA by using the lipofectamine-2000 system. Wound assay in vitro and three-dimensional culture were used to detect the migration and angiogenesis capacity of HUVECs. The morphological changes of transfected cells were observed by confocal and phase contrast microscopy. Our results demonstrated that the decreased expression of ezrin in HUVECs significantly induced the morphogenetic changes and cytoskeletal reorganization of the transfected cells, and also reduced cell migration and angiogenesis capacity in vitro, suggesting that ezrin play an important role in the process of HUVECs migration and angiogenesis.

Versatile roles of extracellular vesicles in cancer

Numerous studies have shown that non-cell-autonomous regulation of cancer cells is an important aspect of tumorigenesis. Cancer cells need to communicate with stromal cells by humoral factors such as VEGF, FGFs, and Wnt in order to survive. Recently, extracellular vesicles (EVs) have also been shown to be involved in cell-cell communication between cancer cells and the surrounding microenvironment and to be important for the development of cancer. In addition, these EVs contain small noncoding RNAs, including microRNAs (miRNAs), which contribute to the malignancy of cancer cells. Here, we provide an overview of current research on EVs, especially miRNAs in EVs. We also propose strategies to treat cancers by targeting EVs around cancer cells.

CD44 increases the efficiency of distant metastasis of breast cancer

Metastasis is the predominant cause of death from cancer yet we have few biomarkers to predict patients at increased risk of metastasis and are unable to effectively treat disseminated disease. Analysis of 448 primary breast tumors determined that expression of the hylauronan receptor CD44 associated with high grade (p = 0.046), ER- (p = 0.001) and PR-negative tumors (p = 0.029), and correlated with increased distant recurrence and reduced disease-free survival in patients with lymph-node positive or large tumors. To determine its functional role in distant metastasis, CD44 was knocked-down in MDA-MB-231 cells using two independent shRNA sequences. Loss of CD44 attenuated tumor cell adhesion to endothelial cells and reduced cell invasion but did not affect proliferation in vitro. To verify the importance of CD44 to post-intravasation events, tumor formation was assessed by quantitative in vivo imaging and post-mortem tissue analysis following an intra-cardiac injection of transfected cells. CD44 knock-down increased survival and decreased overall tumor burden at multiple sites, including the skeleton in vivo. We conclude that elevated CD44 expression on tumour cells within the systemic circulation increases the efficiency of post-intravasation events and distant metastasis in vivo, consistent with its association with increased distant recurrence and reduced disease-free survival in patients.

Decoding the Secret of Cancer by Means of Extracellular Vesicles

One of the recent outstanding developments in cancer biology is the emergence of extracellular vesicles (EVs). EVs, which are small membrane vesicles that contain proteins, mRNAs, long non-coding RNAs, and microRNAs (miRNAs), are secreted by a variety of cells and have been revealed to play an important role in intercellular communications. These molecules function in the recipient cells; this has brought new insight into cell-cell communication. Recent reports have shown that EVs contribute to cancer cell development, including tumor initiation, angiogenesis, immune surveillance, drug resistance, invasion, metastasis, maintenance of cancer stem cells, and EMT phenotype. In this review, I will summarize recent studies on EV-mediated miRNA transfer in cancer biology. Furthermore, I will also highlight the possibility of novel diagnostics and therapy using miRNAs in EVs against cancer.

Establishment and characterization of a metastasis model of human gastric cancer in nude mice

Background

A mouse model of metastasis of human gastric cancer is one of the most important tools for studying the biological mechanisms underlying human gastric cancer metastasis. In this paper, we established a mouse model of metastatic human gastric cancer in nude mice that has a higher rate of tumor formation and metastasis than existing models.

Methods

To generate the mouse model of metastatic human gastric cancer, fresh tumor tissues from patients that have undergone surgery for gastric cancer were subcutaneously implanted in the right and left groins of nude mice. When the implanted tissue grew to 1 cubic centimeter, the mice were killed, and the tumor tissues were examined and resected. The tumor tissues were implanted into nude mice and subjected to pathological examination, immunohistochemical staining, and real-time PCR for cytokeratin 8/18 (CK8/18), E-cadherin, vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1). The mice were also analyzed for metastasis in their peritoneum, abdominal cavity, and internal organs by histopathological examination. Tissues collected from these organs were examined for pathology.

Results

After ten generations of implantation, all mice developed tumor growth at the implanted position, 94 % of the mice developed metastasis to the retroperitoneum and viscera. The implanted and metastatic tumor maintained the same histological features across all generations, and metastasis was observed in the esophagus, stomach, spleen, liver, kidney, adrenal, intestine, and pancreas. These metastatic tumors revealed no detectable expression of CK8/18, E-cadherin, VCAM-1, and ICAM-1.

Conclusions

This model will serve as valuable tool for understanding the metastatic process of human gastric cancer.

A Drosera-bioinspired hydrogel for catching and killing cancer cells

A variety of bioinspired materials have been successfully synthesized to mimic the sophisticated structures or functions of biological systems. However, it is still challenging to develop materials with multiple functions that can be performed synergistically or sequentially. The purpose of this work was to demonstrate a novel bioinspired hydrogel that can interact with cancer cells, functionally similar to Drosera in catching and killing prey. This hydrogel had two layers with the top one functionalized with oligonucleotide aptamers and the bottom one functionalized with double-stranded DNA. The results show that the top hydrogel layer was able to catch target cells with high efficiency and specificity, and that the bottom hydrogel layer could sequester doxorubicin (Dox) for sustained drug release. Importantly, the released Dox could kill 90% of the cells after 1-h residence of the cells on the hydrogel. After the cell release, this bifunctional hydrogel could be regenerated for continuous cell catching and killing. Therefore, the data presented in this study has successfully demonstrated the potential of developing a material system with the functions of attracting, catching and killing diseased cells (e.g., circulating tumor cells) or even invading microorganisms (e.g., bacteria).

RGS22 inhibits pancreatic adenocarcinoma cell migration through the G12/13 α subunit/F-actin pathway

Pancreatic cancer is characterized by the potential for local invasion, allowing it to spread during the early developmental stages of the disease. Regulator of G protein signaling 22 (RGS22) localizes to the cytoplasm in pancreatic adenocarcinoma tissue. We overexpressed RGS22 in the human pancreatic cancer cell line BXPC-3. Cells that overexpressed RGS22 had much lower wound-healing rates and greatly reduced migration compared to the control cells. Conversely, cells in which RGS22 expression had been downregulated had higher wound-healing rates and migration than the control cells. These results confirmed that RGS22 expression suppresses pancreatic adenocarcinoma cell migration. Pull-down and coimmunoprecipitation assays revealed that RGS22 had specific interactions with the heterotrimeric G protein G12 α subunit (GNA12) and GNA13 in the cells. We also demonstrated that in the presence of higher RGS22 expression, the cell deformation and F-actin formation caused by lysophosphatidic acid treatment, is delayed. Constitutively active Gα subunits did not accelerate GTP hydrolysis to GDP. We did not investigate the function of RGS22 as a negative regulator of heterotrimeric G12/13 protein signaling. Our data demonstrate that RGS22 acts as a tumor suppressor, repressing human pancreatic adenocarcinoma cell migration by coupling to GNA12/13, which in turn leads to inhibition of stress fiber formation.

Proton pump inhibitors and histamine 2 blockers are associated with improved overall survival in patients with head and neck squamous carcinoma

It has been postulated that gastroesophageal reflux plays a role in the etiology of head and neck squamous cell carcinomas (HNSCC) and contributes to complications after surgery or during radiotherapy. Antacid medications are commonly used in patients with HNSCC for the management of acid reflux; however, their relationship with outcomes has not been well studied. Associations between histamine receptor-2 antagonists (H2RA) and proton pump inhibitors (PPI) use and treatment outcomes were determined in 596 patients with previously untreated HNSCC enrolled in our SPORE epidemiology program from 2003 to 2008 (median follow-up 55 months). Comprehensive clinical information was entered prospectively in our database. Risk strata were created on the basis of possible confounding prognostic variables (age, demographics, socioeconomics, tumor stage, primary site, smoking status, HPV16 status, and treatment modality); correlations within risk strata were analyzed in a multivariable model. Patients taking antacid medications had significantly better overall survival (OS; PPI alone: P < 0.001; H2RA alone, P = 0.0479; both PPI + H2RA, P = 0.0133). Using multivariable Cox models and adjusting for significant prognostic covariates, both PPIs and H2RAs used were significant prognostic factors for OS, but only H2RAs use for recurrence-free survival in HPV16-positive oropharyngeal patients. We found significant associations between the use of H2RAs and PPIs, alone or in combination, and various clinical characteristics. The findings in this large cohort study indicate that routine use of antacid medications may have significant therapeutic benefit in patients with HNSCC. The reasons for this association remain an active area of investigation and could lead to identification of new treatment and prevention approaches with agents that have minimal toxicities.

IL-17 and insulin/IGF1 enhance adhesion of prostate cancer cells to vascular endothelial cells through CD44-VCAM-1 interaction

BACKGROUND

Extravasation is a critical step in cancer metastasis, in which adhesion of intravascular cancer cells to the vascular endothelial cells is controlled by cell surface adhesion molecules. The role of interleukin-17 (IL-17), insulin, and insulin-like growth factor 1 (IGF1) in adhesion of prostate cancer cells to the vascular endothelial cells is unknown, which is the subject of the present study.

METHODS

Human umbilical vein endothelial cells (HUVECs) and human prostate cancer cell lines (PC-3, DU-145, LNCaP, and C4-2B) were analyzed for expression of vascular cell adhesion molecule 1 (VCAM-1), integrins, and cluster of differentiation 44 (CD44) using flow cytometry and Western blot analysis. The effects of IL-17, insulin, and IGF1 on VCAM-1 expression and adhesion of prostate cancer cells to HUVECs were examined. The interaction of VCAM-1 and CD44 was assessed using immunoprecipitation assays.

RESULTS

Insulin and IGF1 acted with IL-17 to increase VCAM-1 expression in HUVECs. PC-3, DU-145, LNCaP, and C4-2B cells expressed β1 integrin but not α4 integrin. CD44 was expressed by PC-3 and DU-145 cells but not by LNCaP or C4-2B cells. When HUVECs were treated with IL-17, insulin or IGF1, particularly with a combination of IL-17 and insulin (or IGF1), adhesion of PC-3 and DU-145 cells to HUVECs was significantly increased. In contrast, adhesion of LNCaP and C4-2B cells to HUVECs was not affected by treatment of HUVECs with IL-17 and/or insulin/IGF1. CD44 expressed in PC-3 cells physically bound to VCAM-1 expressed in HUVECs.

CONCLUSIONS

CD44-VCAM-1 interaction mediates the adhesion between prostate cancer cells and HUVECs. IL-17 and insulin/IGF1 enhance adhesion of prostate cancer cells to vascular endothelial cells through increasing VCAM-1 expression in the vascular endothelial cells. These findings suggest that IL-17 may act with insulin/IGF1 to promote prostate cancer metastasis.

Visfatin Mediates SCLC Cells Migration across Brain Endothelial Cells through Upregulation of CCL2

Small-cell lung cancer (SCLC) is characterized as an aggressive tumor with brain metastasis. Although preventing SCLC metastasis to the brain is immensely important for survival, the molecular mechanisms of SCLC cells penetrating the blood–brain barrier (BBB) are largely unknown. Recently, visfatin has been considered as a novel pro-inflammatory adipocytokine involved in various cancers. Herein, we present evidence that elevated levels of visfatin in the serum of SCLC patients were associated with brain metastasis, and visfain was increased in NCI-H446 cells, a SCLC cell line, during interacting with human brain microvascular endothelial cells (HBMEC). Using in vitro BBB model, we found that visfatin could promote NCI-H446 cells migration across HBMEC monolayer, while the effect was inhibited by knockdown of visfatin. Furthermore, our findings indicated that CC chemokine ligand 2 (CCL2) was involved in visfatin-mediated NCI-H446 cells transendothelial migtation. Results also showed that the upregulation of CCL2 in the co-culture system was reversed by blockade of visfatin. In particular, visfatin-induced CCL2 was attenuated by specific inhibitor of PI3K/Akt signaling in NCI-H446 cells. Taken together, we demonstrated that visfatin was a prospective target for SCLC metastasis to brain, and understanding the molecular mediators would lead to effective strategies for inhibition of SCLC brain metastasis.

Tissue factor-expressing tumor cells can bind to immobilized recombinant tissue factor pathway inhibitor under static and shear conditions in vitro

Mammary tumors and malignant breast cancer cell lines over-express the coagulation factor, tissue factor (TF). High expression of TF is associated with a poor prognosis in breast cancer. Tissue factor pathway inhibitor (TFPI), the endogenous inhibitor of TF, is constitutively expressed on the endothelium. We hypothesized that TF-expressing tumor cells can bind to immobilized recombinant TFPI, leading to arrest of the tumor cells under shear in vitro. We evaluated the adhesion of breast cancer cells to immobilized TFPI under static and shear conditions (0.35 – 1.3 dyn/cm²). We found that high-TF-expressing breast cancer cells, MDA-MB-231 (with a TF density of 460,000/cell), but not low TF-expressing MCF-7 (with a TF density of 1,400/cell), adhered to recombinant TFPI, under static and shear conditions. Adhesion of MDA-MB-231 cells to TFPI required activated factor VII (FVIIa), but not FX, and was inhibited by a factor VIIa-blocking anti-TF antibody. Under shear, adhesion to TFPI was dependent on the TFPI-coating concentration, FVIIa concentration and shear stress, with no observed adhesion at shear stresses greater than 1.0 dyn/cm². This is the first study showing that TF-expressing tumor cells can be captured by immobilized TFPI, a ligand constitutively expressed on the endothelium, under low shear in vitro. Based on our results, we hypothesize that TFPI could be a novel ligand mediating the arrest of TF-expressing tumor cells in high TFPI-expressing vessels under conditions of low shear during metastasis.

Brain metastatic cancer cells release microRNA-181c-containing extracellular vesicles capable of destructing blood-brain barrier

Brain metastasis is an important cause of mortality in breast cancer patients. A key event during brain metastasis is the migration of cancer cells through blood–brain barrier (BBB). However, the molecular mechanism behind the passage through this natural barrier remains unclear. Here we show that cancer-derived extracellular vesicles (EVs), mediators of cell–cell communication via delivery of proteins and microRNAs (miRNAs), trigger the breakdown of BBB. Importantly, miR-181c promotes the destruction of BBB through the abnormal localization of actin via the downregulation of its target gene, PDPK1. PDPK1 degradation by miR-181c leads to the downregulation of phosphorylated cofilin and the resultant activated cofilin-induced modulation of actin dynamics. Furthermore, we demonstrate that systemic injection of brain metastatic cancer cell-derived EVs promoted brain metastasis of breast cancer cell lines and are preferentially incorporated into the brain in vivo. Taken together, these results indicate a novel mechanism of brain metastasis mediated by EVs that triggers the destruction of BBB.

A key event during metastasis to the brain is the migration of cancer cells through the blood–brain barrier (BBB). Here the authors show that cancer-cell-derived extracellular vesicles promote metastasis by promoting BBB breaching.