The 'chemoinvasion' assay, 25 years and still going strong: the use of reconstituted basement membranes to study cell invasion and angiogenesis

The Potential Influence of Residual or Recurrent Disease on Bevacizumab Treatment Efficacy in Ovarian Cancer: Current Evidence and Future Perspectives

There were high hopes for the new antiangiogenic medicament, bevacizumab, which could inhibit the creation of new blood vessels through binding to isoform A of vascular endothelial growth factor (VEGF). However, it is not only blood vessels that are responsible for tumor cell spread. During the process of tumor growth, lymphangiogenesis is mediated by other members of the VEGF family, specifically VEGF-C and VEGF-D, which act independent to bevacizumab. Therefore, based on the mechanism of bevacizumab action and the processes of angio- and lymphangiogenesis, we formed three hypotheses: (1) if the lymph nodes in primary ovarian cancers are metastatic, the outcome of bevacizumab treatment is worsened; (2) concerning the second-line treatment, bevacizumab will act in a weakened manner if recurrence occurs in lymph nodes as opposed to a local recurrence; (3) patients treated by bevacizumab are more likely to have recurrences in lymph nodes. These hypotheses raise the issue of the existing knowledge gap, which concerns the effect of bevacizumab on metastatic lymph nodes.

An mTurq2-Col4a1 mouse model allows for live visualization of mammalian basement membrane development

Basement membranes (BMs) are specialized sheets of extracellular matrix that underlie epithelial and endothelial tissues. BMs regulate the traffic of cells and molecules between compartments, and participate in signaling, cell migration, and organogenesis. The dynamics of mammalian BMs, however, are poorly understood, largely due to a lack of models in which core BM components are endogenously labeled. Here, we describe the mTurquoise2-Col4a1 mouse in which we fluorescently tag collagen IV, the main component of BMs. Using an innovative planar-sagittal live imaging technique to visualize the BM of developing skin, we directly observe BM deformation during hair follicle budding and basal progenitor cell divisions. The BM's inherent pliability enables dividing cells to remain attached to and deform the BM, rather than lose adhesion as generally thought. Using FRAP, we show BM collagen IV is extremely stable, even during periods of rapid epidermal growth. These findings demonstrate the utility of the mTurq2-Col4a1 mouse to shed new light on mammalian BM developmental dynamics.

From antiquity to contemporary times: how olive oil by-products and waste water can contribute to health

Since antiquity, numerous advantages of olive oil and its by-products have been recognized in various domains, including cooking, skincare, and healthcare. Extra virgin olive oil is a crucial component of the Mediterranean diet; several of its compounds exert antioxidant, anti-proliferative, anti-angiogenic and pro-apoptotic effects against a variety of cancers, and also affect cellular metabolism, targeting cancer cells through their metabolic derangements. Numerous olive tree parts, including leaves, can contribute metabolites useful to human health. Olive mill waste water (OMWW), a dark and pungent liquid residue produced in vast amounts during olive oil extraction, contains high organic matter concentrations that may seriously contaminate the soil and surrounding waters if not managed properly. However, OMWW is a rich source of phytochemicals with various health benefits. In ancient Rome, the farmers would employ what was known as amurca, a mulch-like by-product of olive oil production, for many purposes and applications. Several studies have investigated anti-angiogenic and chemopreventive activities of OMWW extracts. The most prevalent polyphenol in OMWW extracts is hydroxytyrosol (HT). Verbascoside and oleuperin are also abundant. We assessed the impact of one such extract, A009, on endothelial cells (HUVEC) and cancer cells. A009 was anti-angiogenic in several in vitro assays (growth, migration, adhesion) and inhibited angiogenesis in vivo, outperforming HT alone. A009 inhibited cells from several tumors in vitro and in vivo and showed potential cardioprotective effects mitigating cardiotoxicity induced by chemotherapy drugs, commonly used in cancer treatment, and reducing up-regulation of pro-inflammatory markers in cardiomyocytes. Extracts from OMWW and other olive by-products have been evaluated for biological activities by various international research teams. The results obtained make them promising candidates for further development as nutraceutical and cosmeceutical agents or dietary supplement, especially in cancer prevention or even in co-treatments with anti-cancer drugs. Furthermore, their potential to offer cardioprotective benefits opens up avenues for application in the field of cardio-oncology.

A Window into Mammalian Basement Membrane Development: Insights from the mTurq2-Col4a1 Mouse Model

Basement membranes (BMs) are specialized sheets of extracellular matrix that underlie epithelial and endothelial tissues. BMs regulate traffic of cells and molecules between compartments, and participate in signaling, cell migration and organogenesis. The dynamics of mammalian BMs, however, are poorly understood, largely due to a lack of models in which core BM components are endogenously labelled. Here, we describe the mTurquoise2-Col4a1 mouse, in which we fluorescently tag collagen IV, the main component of BMs. Using an innovative Planar-Sagittal live imaging technique to visualize the BM of developing skin, we directly observe BM deformation during hair follicle budding and basal progenitor cell divisions. The BM's inherent pliability enables dividing cells to remain attached to and deform the BM, rather than lose adhesion as generally thought. Using FRAP, we show BM collagen IV is extremely stable, even during periods of rapid epidermal growth. These findings demonstrate the utility of the mTurq2-Col4a1 mouse to shed new light on mammalian BM developmental dynamics.

Kidney injury molecule-1 inhibits metastasis of renal cell carcinoma

Metastasis is present in approximately 30% of patients diagnosed with renal cell carcinoma (RCC) and is associated with a 5-year survival rate of < 15%. Kidney injury molecule 1 (KIM-1), encoded by the HAVCR1 gene, is a proximal tubule cell-surface glycoprotein and a biomarker for early detection of RCC, but its pathophysiological significance in RCC remains unclear. We generated human and murine RCC cell lines either expressing or lacking KIM-1, respectively, and compared their growth and metastatic properties using validated methods. Surprisingly, KIM-1 expression had no effect on cell proliferation or subcutaneous tumour growth in immune deficient (Rag1^−/−) Balb/c mice, but inhibited cell invasion and formation of lung metastasis in the same model. Further, we show that the inhibitory effect of KIM-1 on metastases was observed in both immune deficient and immune competent mice. Transcriptomic profiling identified the mRNA for the pro-metastatic GTPase, Rab27b, to be downregulated significantly in KIM-1 expressing human and murine RCC cells. Finally, analysis of The Cancer Genome Atlas (TCGA) data revealed that elevated HAVCR1 mRNA expression in the two most common types of RCC, clear cell and papillary RCC, tumours correlated with significantly improved overall patient survival. Our findings reveal a novel role for KIM-1 in inhibiting metastasis of RCC and suggests that tumour-associated KIM-1 expression may be a favourable prognostic factor.

Antimetastatic effects of VOflavonoid complexes on A549 cell line

BACKGROUND

Non-small-cell lung cancer (NSCLC) is the most frequent type of lung cancer and more than 90 % of mortality is due to metastasis-related deaths. Flavonoids are considered nutraceuticals due to the variety of pharmacological properties. In this paper, we studied the effects of baicalin, silibinin, apigenin, luteolin, and its oxidovanadium(IV) cation complexes on the viability, adhesion to fibronectin, invasion, and migration on human lung cancer cell line A549. In addition, in order to complete the study of the interaction of VOflavonoids and bovine serum albumin (BSA), the binding ability of silibinin and VOsil to the protein was evaluated.

METHOD

To establish the non-cytotoxic concentration range of the tested compounds, the cancer cell viability was evaluated using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assay. Cell migration and invasion assays were performed using Boyden chambers and adhesion assay using MTT method. The interaction of compounds with BSA were investigated in physiological buffer (pH = 7.4) by fluorescence spectroscopy.

RESULTS

All complexes inhibited the metastatic cascade steps to a greater extent than their respective ligands. Likewise, based on binding constant values (K_b) for BSA-silibinin and BSA-VOsil, we can suggest that both compounds can interact with the protein.

CONCLUSION

Although all the complexes suppressed cell adhesion, invasion and migration, VOlut can be considered as a good candidate to continue the trials because it presented encouraging results as a potential antitumor and antimetastatic agent, and can be transported by BSA.

Three-Dimensional Culture System of Cancer Cells Combined with Biomaterials for Drug Screening

Simple Summary

For the research and development of drug discovery, it is of prime importance to construct the three-dimensional (3D) tissue models in vitro. To this end, the enhancement design of cell function and activity by making use of biomaterials is essential. In this review, 3D culture systems of cancer cells combined with several biomaterials for anticancer drug screening are introduced.

Abstract

Anticancer drug screening is one of the most important research and development processes to develop new drugs for cancer treatment. However, there is a problem resulting in gaps between the in vitro drug screening and preclinical or clinical study. This is mainly because the condition of cancer cell culture is quite different from that in vivo. As a trial to mimic the in vivo cancer environment, there has been some research on a three-dimensional (3D) culture system by making use of biomaterials. The 3D culture technologies enable us to give cancer cells an in vitro environment close to the in vivo condition. Cancer cells modified to replicate the in vivo cancer environment will promote the biological research or drug discovery of cancers. This review introduces the in vitro research of 3D cell culture systems with biomaterials in addition to a brief summary of the cancer environment.

Association of Mps one binder kinase activator 1 (MOB1) expression with poor disease-free survival in individuals with non-small cell lung cancer

Background

Mps one binder kinase activator 1 (MOB1) is a core component of the Hippo signaling pathway and has been implicated as a tumor suppressor. Here, we evaluated the possible relationship of MOB1 expression in non‐small cell lung cancer (NSCLC) to prognosis.

Methods

We retrospectively analyzed 205 lung adenocarcinoma patients treated at Kyushu University Hospital between November 2007 and October 2012. MOB1 expression in tumor cells of surgical specimens was evaluated by immunohistochemistry. Invasive activity of NSCLC cell lines in vitro was measured with a transwell assay.

Results

Expression of MOB1 was classified as high in 105 of the 205 (51.2%) tumor specimens, and such high expression was significantly associated with poor disease‐free survival (P = 0.0161). Among the various clinicopathologic parameters examined, high MOB1 expression was significantly associated only with intratumoral vascular invasion (P = 0.0005). Multivariate analysis also identified high MOB1 expression as a significant independent risk factor for disease‐free survival (P = 0.0319). The invasiveness of H1299 cells in vitro was increased or attenuated by overexpression or knockdown of MOB1, respectively.

Conclusions

Our results suggest that MOB1 might promote early recurrence of NSCLC by increasing vascular invasion by tumor cells.

Key points

Significant findings of the study

We found that high MOB1 expression in surgical specimens of lung adenocarcinoma was associated with poor disease‐free survival and with intratumoral vascular invasion. MOB1 expression also promoted the invasiveness of NSCLC cells in vitro.

What this study adds

Our results thus suggest that high MOB1 expression is a risk factor for early postoperative recurrence in lung adenocarcinoma.

A lysosomal hydrolase receptor, CPBF2, is associated with motility and invasion of the enteric protozoan parasite Entamoeba histolytica

Proper targeting and secretion of lysosomal hydrolases are regulated by transporting receptors. Entamoeba histolytica, the enteric protozoan parasite responsible for human amebiasis, has a unique family of lysosomal hydrolase receptors, cysteine protease binding protein family, CPBF. CPBFs, consisting of 11 members with conserved domain organization, bind to a wide range of cargos including cysteine proteases and glycosidases, which are also known to be involved in pathogenesis of this parasite. In this study, we characterized one of CPBFs, CPBF2, which is involved in cell motility and extracellular matrix invasion. Unexpectedly, these roles of CPBF were not related to its cargo, α-amylase. This is the first demonstration that a putative hydrolase receptor is involved in cell motility and invasion in parasitic protozoa.

Acetyl-L-Carnitine downregulates invasion (CXCR4/CXCL12, MMP-9) and angiogenesis (VEGF, CXCL8) pathways in prostate cancer cells: rationale for prevention and interception strategies

Background

Prostate cancer (PCa) is a leading cause of cancer-related death in males worldwide. Exacerbated inflammation and angiogenesis have been largely demonstrated to contribute to PCa progression. Diverse naturally occurring compounds and dietary supplements are endowed with anti-oxidant, anti-inflammatory and anti-angiogenic activities, representing valid compounds to target the aberrant cytokine/chemokine production governing PCa progression and angiogenesis, in a chemopreventive setting. Using mass spectrometry analysis on serum samples of prostate cancer patients, we have previously found higher levels of carnitines in non-cancer individuals, suggesting a protective role. Here we investigated the ability of Acetyl-L-carnitine (ALCAR) to interfere with key functional properties of prostate cancer progression and angiogenesis in vitro and in vivo and identified target molecules modulated by ALCAR.

Methods

The chemopreventive/angiopreventive activities ALCAR were investigated in vitro on four different prostate cancer (PCa) cell lines (PC-3, DU-145, LNCaP, 22Rv1) and a benign prostatic hyperplasia (BPH) cell line. The effects of ALCAR on the induction of apoptosis and cell cycle arrest were investigated by flow cytometry (FC). Functional analysis of cell adhesion, migration and invasion (Boyden chambers) were performed. ALCAR modulation of surface antigen receptor (chemokines) and intracellular cytokine production was assessed by FC. The release of pro-angiogenic factors was detected by a multiplex immunoassay. The effects of ALCAR on PCa cell growth in vivo was investigated using tumour xenografts.

Results

We found that ALCAR reduces cell proliferation, induces apoptosis, hinders the production of pro inflammatory cytokines (TNF-α and IFN-γ) and of chemokines CCL2, CXCL12 and receptor CXCR4 involved in the chemotactic axis and impairs the adhesion, migration and invasion capabilities of PCa and BPH cells in vitro. ALCAR exerts angiopreventive activities on PCa by reducing production/release of pro angiogenic factors (VEGF, CXCL8, CCL2, angiogenin) and metalloprotease MMP-9. Exposure of endothelial cells to conditioned media from PCa cells, pre-treated with ALCAR, inhibited the expression of CXCR4, CXCR1, CXCR2 and CCR2 compared to those from untreated cells. Oral administration (drinking water) of ALCAR to mice xenografted with two different PCa cell lines, resulted in reduced tumour cell growth in vivo.

Conclusions

Our results highlight the capability of ALCAR to down-modulate growth, adhesion, migration and invasion of prostate cancer cells, by reducing the production of several crucial chemokines, cytokines and MMP9. ALCAR is a widely diffused dietary supplements and our findings provide a rational for studying ALCAR as a possible molecule for chemoprevention approaches in subjects at high risk to develop prostate cancer. We propose ALCAR as a new possible “repurposed agent’ for cancer prevention and interception, similar to aspirin, metformin or beta-blockers.

Downregulation of Pro-Inflammatory and Pro-Angiogenic Pathways in Prostate Cancer Cells by a Polyphenol-Rich Extract from Olive Mill Wastewater

Dietary phytochemicals are particularly attractive for chemoprevention and are able to modulate several signal transduction pathways linked with cancer. Olive oil, a major component of the Mediterranean diet, is an abundant source of phenolic compounds. Olive oil production is associated with the generation of a waste material, termed 'olive mill wastewater' (OMWW) that have been reported to contain water-soluble polyphenols. Prostate cancer (PCa) is considered as an ideal cancer type for chemopreventive approaches, due to its wide incidence but relatively long latency period and progression time. Here, we investigated activities associated with potential preventive properties of a polyphenol-rich olive mill wastewater extract, OMWW (A009), on three in vitro models of PCa. A009 was able to inhibit PCa cell proliferation, adhesion, migration, and invasion. Molecularly, we found that A009 targeted NF-κB and reduced pro-angiogenic growth factor, VEGF, CXCL8, and CXCL12 production. IL-6/STAT3 axis was also regulated by the extract. A009 shows promising properties, and purified hydroxytyrosol (HyT), the major polyphenol component of A009, was also active but not always as effective as A009. Finally, our results support the idea of repositioning a food waste-derived material for nutraceutical employment, with environmental and industrial cost management benefits.

The manganese(III) porphyrin MnTnHex-2-PyP5+ modulates intracellular ROS and breast cancer cell migration: Impact on doxorubicin-treated cells

Manganese(III) porphyrins (MnPs) are superoxide dismutase (SOD) mimics with demonstrated beneficial effects in cancer treatment in combination with chemo- and radiotherapy regimens. Despite the ongoing clinical trials, little is known about the effect of MnPs on metastasis, being therefore essential to understand how MnPs affect this process. In the present work, the impact of the MnP MnTnHex-2-PyP⁵⁺ in metastasis-related processes was assessed in breast cancer cells (MCF-7 and MDA-MB-231), alone or in combination with doxorubicin (dox). The co-treatment of cells with non-cytotoxic concentrations of MnP and dox altered intracellular ROS, increasing H₂O₂. While MnP alone did not modify cell migration, the co-exposure led to a reduction in collective cell migration and chemotaxis. In addition, the MnP reduced the dox-induced increase in random migration of MDA-MB-231 cells. Treatment with either MnP or dox decreased the proteolytic invasion of MDA-MB-231 cells, although the effect was more pronounced upon co-exposure with both compounds. Moreover, to explore the cellular mechanisms underlying the observed effects, cell adhesion, spreading, focal adhesions, and NF-κB activation were also studied. Although differential effects were observed according to the endpoints analysed, overall, the alterations induced by MnP in dox-treated cells were consistent with a therapeutically favorable outcome.

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MnPs are SOD mimics with potential therapeutic applications in cancer.

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The impact of an MnP on breast cancer metastasis-related processes was assessed.

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Treatment with MnP+dox decreased collective cell migration, chemotaxis and invasion.

•

MnP also reduced the dox-induced increase in random migration of MDA-MB-231 cells.

•

Combination of MnP with dox revealed therapeutically favorable effects.

Acetyl-l-carnitine is an anti-angiogenic agent targeting the VEGFR2 and CXCR4 pathways

Carnitines play an important role in the energy exchange in cells, and are involved in the transport of fatty acids across the inner mitochondrial membrane. l-Acetylcarnitine (ALCAR) is an acetic acid ester of carnitine that has higher bioavailability and is considered a fat-burning energizer supplement. We previously found that in serum samples from prostate cancer (PCa) patients, 3 carnitine family members were significantly decreased, suggesting a potential protective role of carnitine against PCa. Several studies support beneficial effects of carnitines on cancer, no study has investigated the activities of carnitine on tumor angiogenesis. We examined whether ALCAR acts as an "angiopreventive" compound and studied the molecular mechanisms involved. We found that ALCAR was able to limit inflammatory angiogenesis by reducing stimulated endothelial cell and macrophage infiltration in vitro and in vivo. Molecularly, we show that ALCAR downregulates VEGF, VEGFR2, CXCL12, CXCR4 and FAK pathways. ALCAR blocked the activation of NF-κB and ICAM-1 and reduced the adhesion of a monocyte cell line to endothelial cells. This is the first study showing that ALCAR has anti-angiogenic and anti-inflammatory properties and might be an attractive candidate for cancer angioprevention.

A highly invasive subpopulation of MDA-MB-231 breast cancer cells shows accelerated growth, differential chemoresistance, features of apocrine tumors and reduced tumorigenicity in vivo

The acquisition of an invasive phenotype is a prerequisite for metastasization, yet it is not clear whether or to which extent the invasive phenotype is linked to other features characteristic of metastatic cells. We selected an invasive subpopulation from the triple negative breast cancer cell line MDA-MB-231, performing repeated cycles of preparative assays of invasion through Matrigel covered membranes. The invasive sub-population of MDA-MB-231 cells exhibits stronger migratory capacity as compared to parental cells confirming the highly invasive potential of the selected cell line. Prolonged cultivation of these cells did not abolish the invasive phenotype. ArrayCGH, DNA index quantification and karyotype analyses confirmed a common genetic origin of the parental and invasive subpopulations and revealed discrete structural differences of the invasive subpopulation including increased ploidy and the absence of a characteristic amplification of chromosome 5p14.1-15.33. Gene expression analyses showed a drastically altered expression profile including features of apocrine breast cancers and of invasion related matrix-metalloproteases and cytokines. The invasive cells showed accelerated proliferation, increased apoptosis, and an altered pattern of chemo-sensitivity with lower IC50 values for drugs affecting the mitotic apparatus. However, the invasive cell population is significantly less tumorigenic in orthotopic mouse xenografts suggesting that the acquisition of the invasive capacity and the achievement of metastatic growth potential are distinct events.

Laminin-111 peptide C16 regulates invadopodia activity of malignant cells through β1 integrin, Src and ERK 1/2

Laminin peptides influence tumor behavior. In this study, we addressed whether laminin peptide C16 (KAFDITYVRLKF, γ1 chain) would increase invadopodia activity of cells from squamous cell carcinoma (CAL27) and fibrosarcoma (HT1080). We found that C16 stimulates invadopodia activity over time in both cell lines. Rhodamine-conjugated C16 decorates the edge of cells, suggesting a possible binding to membrane receptors. Flow cytometry showed that C16 increases activated β1 integrin, and β1 integrin miRNA-mediated depletion diminishes C16-induced invadopodia activity in both cell lines. C16 stimulates Src and ERK 1/2 phosphorylation, and ERK 1/2 inhibition decreases peptide-induced invadopodia activity. C16 also increases cortactin phosphorylation in both cells lines. Based on our findings, we propose that C16 regulates invadopodia activity over time of squamous carcinoma and fibrosarcoma cells, probably through β1 integrin, Src and ERK 1/2 signaling pathways.

Culturing substrates influence the morphological, mechanical and biochemical features of lung adenocarcinoma cells cultured in 2D or 3D

Alternative models such as three-dimensional (3D) cell cultures represent a distinct milestone towards capturing the realities of cancer biology in vitro and reduce animal experimentation in the preclinical stage of drug discovery. Significant work remains to be done to understand how substrates used in in vitro alternatives influence cancer cells phenotype and drug efficacy responses, so that to accurately link such models to specific in vivo disease scenarios. Our study describes how the morphological, mechanical and biochemical properties of adenocarcinoma (A549) cells change in response to a 3D environment and varying substrates. Confocal Laser Scanning (LSCM), He-Ion (HIM) and Atomic Force (AFM) microscopies, supported by ELISA and Western blotting, were used. These techniques enabled us to evaluate the shape, cytoskeletal organization, roughness, stiffness and biochemical signatures of cells grown within soft 3D matrices (PuraMatrix™ and Matrigel™), and to compare them to those of cells cultured on two-dimensional glass substrates. Cell cultures are also characterized for their biological response to docetaxel, a taxane-type drug used in Non-Small-Cell Lung Cancer (NSCLC) treatment. Our results offer an advanced biophysical insight into the properties and potential application of 3D cultures of A549 cells as in vitro alternatives in lung cancer research.

In vitro characterization of spheres derived from colorectal cancer cell lines

Spherical cultures (SCs) can be regarded in cancer research as a link between in vitro investigations on cancer lines and in vivo studies of tumor development. SCs are believed to mimic tumor architecture and to be enriched in cancer stem cell-like cells (CSC-like cells). In the present study we characterized colonospheres derived from colorectal cancer (CRC) cell lines, and we confirmed the ability of HCT116 and HT29 cell lines to form spheres within serum-free medium, however, the detailed analysis presented the major differences concerning their characteristics including morphology, phenotype, proliferative potential, distribution in the cell cycle phases and spherogenicity. Moreover, after we magnetically separated CD133+ and CD133- cells we could conduct the analogical analysis as we performed for the original cells. We observed that all cellular fractions unveiled sphere formation capacity, even when cultured in limited number of cells per well and only SCs originated from CD133+ fraction resembled morphologically the parental spheres. Both CD133+ and CD133- subsets derived from HCT116 line were more enriched in cells in G0/G1 phase of the cell cycle in comparison to their HT29 analogues. Additionally, proliferative potential also varied amongst all studied fractions. Surprisingly, 3-D invasion assay revealed that only HCT116-derived populations were able to migrate into extended regions of Matrigel Matrix confirming their higher aggressiveness. Our results provided comprehensive characterization of CRC cell lines culture in adherent and spherical forms and, what seems to be the most advantageous, the comparison of two distinct fractions after magnetic separation. As we found the specific features of cells presented line- and expansion mode-dependency, thus, such complete description might appear crucial before CRC lines would be involved into sophisticated assays, especially focused on potentially novel therapeutic agents targeting CSC-like cells.

Microfluidic modeling of the biophysical microenvironment in tumor cell invasion

Tumor cell invasion, whether penetrating through the extracellular matrix (ECM) or crossing a vascular endothelium, is a critical step in the cancer metastatic cascade. Along the way from a primary tumor to a distant metastatic site, tumor cells interact actively with the microenvironment either via biomechanical (e. g. ECM stiffness) or biochemical (e.g. secreted cytokines) signals. Increasingly, it is recognized that the tumor microenvironment (TME) is a critical player in tumor cell invasion. A main challenge for the mechanistic understanding of tumor cell-TME interactions comes from the complexity of the TME, which consists of extracellular matrices, fluid flows, cytokine gradients and other cell types. It is difficult to control TME parameters in conventional in vitro experimental designs such as Boyden chambers or in vivo such as in mouse models. Microfluidics has emerged as an enabling tool for exploring the TME parameter space because of its ease of use in recreating a complex and physiologically realistic three dimensional TME with well-defined spatial and temporal control. In this perspective, we will discuss designing principles for modeling the biophysical microenvironment (biological flows and ECM) for tumor cells using microfluidic devices and the potential microfluidic technology holds in recreating a physiologically realistic tumor microenvironment. The focus will be on applications of microfluidic models in tumor cell invasion.

Live-cell confocal microscopy and quantitative 4D image analysis of anchor-cell invasion through the basement membrane in Caenorhabditis elegans

Cell invasion through basement membrane (BM) barriers is crucial in development, leukocyte trafficking and the spread of cancer. The mechanisms that direct invasion, despite their importance in normal and disease states, are poorly understood, largely because of the inability to visualize dynamic cell-BM interactions in vivo. This protocol describes multichannel time-lapse confocal imaging of anchor-cell invasion in live Caenorhabditis elegans. Methods presented include outline-slide preparation and worm growth synchronization (15 min), mounting (20 min), image acquisition (20-180 min), image processing (20 min) and quantitative analysis (variable timing). The acquired images enable direct measurement of invasive dynamics including formation of invadopodia and cell-membrane protrusions, and removal of BM. This protocol can be combined with genetic analysis, molecular-activity probes and optogenetic approaches to uncover the molecular mechanisms underlying cell invasion. These methods can also be readily adapted by any worm laboratory for real-time analysis of cell migration, BM turnover and cell-membrane dynamics.

Synthesis and antiangiogenic activity study of new hop chalcone Xanthohumol analogues

Angiogenesis induction is a hallmark of cancer. Antiangiogenic properties of Xanthohumol (XN), a naturally occurring prenylated chalcone from hops, have been widely reported. Here we describe the synthesis and study the antiangiogenic activity in vitro of a series of XN derivatives, where different substituents on the B-ring of the chalcone scaffold were inserted. The new XN derivatives inhibited human umbilical-vein endothelial cell (HUVEC) proliferation, adhesion, migration, invasion and their ability to form capillary-like structures in vitro at 10 μM concentration. The preliminary results indicate that the phenolic OH group in R, present in natural XN, is not necessary for having antiangiogenic activity. In fact, the most effective compound from this series, 13, was characterized by a para-methoxy group in R and a fluorine atom in R₂ on B-ring. This study paves the way for future development of synthetic analogues of XN to be used as cancer angiopreventive and chemopreventive agents.

An Efficient and Flexible Cell Aggregation Method for 3D Spheroid Production

Monolayer cell culture does not adequately model the in vivo behavior of tissues, which involves complex cell-cell and cell-matrix interactions. Three-dimensional (3D) cell culture techniques are a recent innovation developed to address the shortcomings of adherent cell culture. While several techniques for generating tissue analogues in vitro have been developed, these methods are frequently complex, expensive to establish, require specialized equipment, and are generally limited by compatibility with only certain cell types. Here, we describe a rapid and flexible protocol for aggregating cells into multicellular 3D spheroids of consistent size that is compatible with growth of a variety of tumor and normal cell lines. We utilize varying concentrations of serum and methyl cellulose (MC) to promote anchorage-independent spheroid generation and prevent the formation of cell monolayers in a highly reproducible manner. Optimal conditions for individual cell lines can be achieved by adjusting MC or serum concentrations in the spheroid formation medium. The 3D spheroids generated can be collected for use in a wide range of applications, including cell signaling or gene expression studies, candidate drug screening, or in the study of cellular processes such as tumor cell invasion and migration. The protocol is also readily adapted to generate clonal spheroids from single cells, and can be adapted to assess anchorage-independent growth and anoikis-resistance. Overall, our protocol provides an easily modifiable method for generating and utilizing 3D cell spheroids in order to recapitulate the 3D microenvironment of tissues and model the in vivo growth of normal and tumor cells.

HMGB1 is negatively correlated with the development of endometrial carcinoma and prevents cancer cell invasion and metastasis by inhibiting the process of epithelial-to-mesenchymal transition

High-mobility group box protein 1 (HMGB1), a nuclear protein that plays a significant role in DNA architecture and transcription, was correlated with the progression of some types of cancer. However, the role of HMGB1 in endometrial cancer cell invasion and metastasis remains unexplored. HMGB1 expression was initially assessed by immunohistochemistry and reverse transcription-quantitative polymerase chain reaction (RT-qPCR) in normal endometrial tissue and endometrial carcinoma tissue. High expressions of HMGB1 protein were detected in normal endometrial tissues; however, in endometrial cancer tissues, the expressions of HMGB1 were found to be very weak. Furthermore, HMGB1 expressions were negatively correlated with advanced stage and lymph node metastasis in endometrial cancer. Then by RT-qPCR, Western blot and immunocytochemistry, HMGB1 was also detected in primary cultured endometrial cells and four kinds of endometrial cancer cell lines (Ishikawa, HEC-1A, HEC-1B and KLE). We found that the expression of HMGB1 was much higher in normal endometrial cells than in endometrial cancer cells, and reduced expression levels of HMGB1 were observed especially in the highly metastatic cell lines. Using lentivirus transfection, HMGB1 small hairpin RNA was constructed, and this infected the lowly invasive endometrial cancer cell lines, Ishikawa and HEC-1B. HMGB1 knockdown significantly enhanced the proliferation, invasion and metastasis of endometrial cancer cells and induced the process of epithelial-to-mesenchymal transition. These results can contribute to the development of a new potential therapeutic target for endometrial cancer.

Tyrosine kinase inhibitor TKI-258 inhibits cell motility in oral squamous cell carcinoma in vitro

BACKGROUND

Oral squamous cell carcinoma is extremely invasive, and this behavior is regulated by binding of extracellular molecules to the cell membrane receptors. The TKI-258 inhibits phosphorylation of FGFRs VEGFRs and PDGFRs. Our aim was to analyze the effect of TKI-258 treatment in cell movement using SCC-4 cell line from human oral squamous cell carcinoma.

METHODS

F-actin was stained with rhodamine phalloidin, and confocal analysis was performed. The migration and invasion (membrane covered with Matrigel^™ ) three-dimensional assays were performed, and control and cells treated with TKI-258 that migrated through the membrane were counted after 24 h.

RESULTS

Control cells presented abundant cytoplasm with F-actin wide distributed and evident cell cortex; however, treated (1, 5 and 10 μM TKI-258) cells showed round morphology, scanty cytoplasm, F-actin disorganized and preserved cell cortex. TKI-258 (1, 5, and 10 μM) treatment inhibits migrating cells (ANOVA, F = 97.749, d.f. = 3, 10; P < 0.0001), and it was concentration dependent. Invading cell treated with 5 μM TKI-258 was significantly lower (t = 6.708, d.f. = 5, P < 0.001).

CONCLUSIONS

These results suggest that the tyrosine kinase inhibitor TKI-258 has an inhibitory effect on cell motility, affecting F-actin, cell migration, and cell invasion, and probably, these processes are regulated by signaling pathways FGFRs and/or PDGFRs and/or VEGFRs.

Fenretinide (4-HPR) Targets Caspase-9, ERK 1/2 and the Wnt3a/β-Catenin Pathway in Medulloblastoma Cells and Medulloblastoma Cell Spheroids

Medulloblastoma (MB), a neuroectodermal tumor arising in the cerebellum, represents the most frequent childhood brain malignancy. Current treatments for MB combine radiation and chemotherapy and are often associated with relevant side effects; novel therapeutic strategies are urgently needed. N-(4-Hydroxyphenyl) retinamide (4-HPR, fenretinide), a synthetic analogue of all-trans retinoic acid, has emerged as a promising and well-tolerated cancer chemopreventive and chemotherapeutic agent for various neoplasms, from breast cancer to neuroblastoma. Here we investigated the effects of 4-HPR on MB cell lines and identified the mechanism of action for a potential use in therapy of MB. Flow cytometry analysis was performed to evaluate 4-HPR induction of apoptosis and oxygen reactive species (ROS) production, as well as cell cycle effects. Functional analysis to determine 4-HPR ability to interfere with MB cell migration and invasion were performed. Western Blot analysis were used to investigate the crucial molecules involved in selected signaling pathways associated with apoptosis (caspase-9 and PARP-1), cell survival (ERK 1/2) and tumor progression (Wnt3a and β-catenin). We show that 4-HPR induces caspase 9-dependent cell death in DAOY and ONS-76 cells, associated with increased ROS generation, suggesting that free radical intermediates might be directly involved. We observed 4-HPR induction of cell cycle arrest in G1/S phase, inactivated β-catenin, and inhibition of MB cell migration and invasion. We also evaluated the ability of 4-HPR to target MB cancer-stem/cancer-initiating cells, using an MB spheroids model, followed by flow cytometry and quantitative real-time PCR. 4-HPR treatment reduced DAOY and ONS-76 spheroid formation, in term of number and size. Decreased expression of the surface markers CD133⁺ and ABCG2⁺ as well as Oct-4 and Sox-2 gene expression were observed on BTICs treated with 4-HPR further reducing BITIC invasive activities. Finally, we analyzed 4-HPR ability to inhibit MB tumor cell growth in vivo in nude mice. Taken together, our data suggest that 4-HPR targets both parental and MB tumor stem/initiating cell-like populations. Since 4-HPR exerts low toxicity, it could represent a valid compound in the treatment of human MB.

Quantification of cancer cell extravasation in vivo

Cancer cell 'invasiveness' is one of the main driving forces in cancer metastasis, and assays that quantify this key attribute of cancer cells are crucial in cancer metastasis research. The research goal of many laboratories is to elucidate the signaling pathways and effectors that are responsible for cancer cell invasion, but many of these experiments rely on in vitro methods that do not specifically simulate individual steps of the metastatic cascade. Cancer cell extravasation is arguably the most important example of invasion in the metastatic cascade, whereby a single cancer cell undergoes transendothelial migration, forming invasive processes known as invadopodia to mediate translocation of the tumor cell from the vessel lumen into tissue in vivo. We have developed a rapid, reproducible and economical technique to evaluate cancer cell invasiveness by quantifying in vivo rates of cancer cell extravasation in the chorioallantoic membrane (CAM) of chicken embryos. This technique enables the investigator to perform well-powered loss-of-function studies of cancer cell extravasation within 24 h, and it can be used to identify and validate drugs with potential antimetastatic effects that specifically target cancer cell extravasation. A key advantage of this technique over similar assays is that intravascular cancer cells within the capillary bed of the CAM are clearly distinct from extravasated cells, which makes cancer cell extravasation easy to detect. An intermediate level of experience in injections of the chorioallantoic membrane of avian embryos and cell culture techniques is required to carry out the protocol.

The activation of the NF-κB-JNK pathway is independent of the PI3K-Rac1-JNK pathway involved in the bFGF-regulated human fibroblast cell migration

BACKGROUND

Skin wound healing is a complex process that repairs multiple organ-tissues. Fibroblasts are key players of skin cells, whose migration is important during wound healing process. bFGF has shown a great efficacy to promote cell migration, but the precise mechanism by which bFGF regulates cell migration remains elusive.

OBJECTIVE

The aim of this study was to find bFGF-regulated gene pools and further identify target molecules that participated in human fibroblast cell migration.

METHODS

Skin primary fibroblasts and rat skin wound model were used to demonstrate the novel mechanism of bFGF regulating cell migration to accelerate wound healing. Cell migration was determined using the wound healing scratch assay. The differentially expressed genes and numerous biochemical pathways after bFGF treatment were identified by RNA-Seq analysis, and differentially expressed genes were further verified by qRT-PCR. siRNA duplex target to interfering the expression of PI3-kinase (p110α) was transformed into NIH/3T3 cells. Western blotting analysis was used to determine marker protein expressions. The invasive activity of fibroblasts was measured using 3D spheroid cell invasion assay.

RESULTS

RNA-Seq analysis identified numerous biochemical pathways including the NF-κB pathway under the control of FGF signaling. bFGF negatively regulates the phosphorylation of IκB-α, the most well studied NF-κB signaling regulator while bFGF induces JNK phosphorylation. Application of Bay11-7082, a representative NF-κB inhibitor promoted cell migration, invasion and enhanced the JNKs phosphorylation. However, inhibition of JNKs blocked cell migration when NF-κB is inhibited. Moreover, application of the PI3K inhibitor LY294002 together with Bay11-7082 maintained normal cell migration and knocking-down PI3K (p110α) by a specific siRNA inhibited JNKs phosphorylation while maintaining normal IκBα phosphorylation, indicating that PI3K and NF-κB signaling independently regulate JNKs activation. In addition, administration of bFGF or Bay11-7082 promoted rat skin wound repair and accelerated the invasion of fibroblasts.

CONCLUSION

This study sheds light on the mode of action of bFGF and identifies that the NF-κB-JNKs pathway is independent of the PI3K-JNKs pathway to accelerate fibroblast migration. In addition, bFGF and the relief of inflammation could be a favorable therapeutic approach for skin wound healing.

A novel human leiomyoma tissue derived matrix for cell culture studies

Background

The composition of the matrix molecules is important in in vitro cell culture experiments of e.g. human cancer invasion and vessel formation. Currently, the mouse Engelbreth-Holm-Swarm (EHS) sarcoma -derived products, such as Matrigel®, are the most commonly used tumor microenvironment (TME) mimicking matrices for experimental studies. However, since Matrigel® is non-human in origin, its molecular composition does not accurately simulate human TME. We have previously described a solid 3D organotypic myoma disc invasion assay, which is derived from human uterus benign leiomyoma tumor. Here, we describe the preparation and analyses of a processed, gelatinous leiomyoma matrix, named Myogel.

Methods

A total protein extract, Myogel, was formulated from myoma. The protein contents of Myogel were characterized and its composition and properties compared with a commercial mouse Matrigel®. Myogel was tested and compared to Matrigel® in human cell adhesion, migration, invasion, colony formation, spheroid culture and vessel formation experiments, as well as in a 3D hanging drop video image analysis.

Results

We demonstrated that only 34 % of Myogel’s molecular content was similar to Matrigel®. All test results showed that Myogel was comparable with Matrigel®, and when mixed with low-melting agarose (Myogel-LMA) it was superior to Matrigel® in in vitro Transwell® invasion and capillary formation assays.

Conclusions

In conclusion, we have developed a novel Myogel TME matrix, which is recommended for in vitro human cell culture experiments since it closely mimics the human tumor microenvironment of solid cancers.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1944-z) contains supplementary material, which is available to authorized users.

Chick Heart Invasion Assay for Testing the Invasiveness of Cancer Cells and the Activity of Potentially Anti-invasive Compounds

The goal of the chick heart assay is to offer a relevant organ culture method to study tumor invasion in three dimensions. The assay can distinguish between invasive and non-invasive cells, and enables study of the effects of test compounds on tumor invasion. Cancer cells - either as aggregates or single cells - are confronted with fragments of embryonic chick heart. After organ culture in suspension for a few days or weeks the confronting cultures are fixed and embedded in paraffin for histological analysis. The three-dimensional interaction between the cancer cells and the normal tissue is then reconstructed from serial sections stained with hematoxylin-eosin or after immunohistochemical staining for epitopes in the heart tissue or the confronting cancer cells. The assay is consistent with the recent concept that cancer invasion is the result of molecular interactions between the cancer cells and their neighbouring stromal host elements (myofibroblasts, endothelial cells, extracellular matrix components, etc.). Here, this stromal environment is offered to the cancer cells as a living tissue fragment. Supporting aspects to the relevance of the assay are multiple. Invasion in the assay is in accordance with the criteria of cancer invasion: progressive occupation and replacement in time and space of the host tissue, and invasiveness and non-invasiveness in vivo of the confronting cells generally correlates with the outcome of the assay. Furthermore, the invasion pattern of cells in vivo, as defined by pathologists, is reflected in the histological images in the assay. Quantitative structure-activity relation (QSAR) analysis of the results obtained with numerous potentially anti-invasive organic congener compounds allowed the study of structure-activity relations for flavonoids and chalcones, and known anti-metastatic drugs used in the clinic (e.g., microtubule inhibitors) inhibit invasion in the assay as well. However, the assay does not take into account immunological contributions to cancer invasion.

Role of the Copper(II) Complex Cu[15]pyN5 in Intracellular ROS and Breast Cancer Cell Motility and Invasion

Multiple mechanisms related to metastases undergo redox regulation. Cu[15]pyN5 is a redox-active copper(II) complex previously studied as a chemotherapy sensitizer in mammary cells. The effects of a cotreatment with Cu[15]pyN5 and doxorubicin (dox) were evaluated in two human breast cancer cell lines: MCF7 (low aggressiveness) and MDA-MB-231 (highly aggressive). Cu[15]pyN5 decreased MCF7-directed cell migration. In addition, a cotreatment with dox and Cu[15]pyN5 reduced the proteolytic invasion of MDA-MB-231 cells. Cell detachment was not affected by exposure to these agents. Cu[15]pyN5 and dox significantly increased intracellular ROS in both cell lines. This increase could be at least partially due to H2 O2 accumulation. The combination of Cu[15]pyN5 with dox may be beneficial in breast cancer treatment as it could help reduce cancer cell migration and invasion. Moreover, the ligand [15]pyN5 has a high affinity for copper(II) and displays potential anti-angiogenic properties. Overall, we present a potential drug that might arrest the progression of breast cancer by different and complementary mechanisms.

Reviewing and reconsidering invasion assays in head and neck cancer

Head and neck squamous cell carcinomas (HNSCC) are malignant tumors that arise from the surface epithelium of the oral cavity, oropharynx and larynx, primarily due to exposure to chemical carcinogens or the human papilloma virus. Due to their location, dental practitioners are well-positioned to detect the lesions. Deadlier than lymphoma or melanoma, HNSCC is incompletely understood. For these reasons, dental practitioners and researchers are focused on understanding HNSCC and the processes driving it. One of these critical processes is invasion, the degradation of the basement membrane by HNSCC cells with subsequent movement into the underlying connective tissue, blood vessels or nerves. Cancer cells metastasize to distant sites via the blood vessels, lymphatics and nerves. Metastasis is associated with poor survival. Since invasion is essential for development and metastasis of HNSCC, it is essential to understand the mechanism(s) driving this process. Elucidation of the mechanisms involved will facilitate the development of targeted treatment, thereby accelerating development of precision/personalized medicine to treat HNSCC. Robust in vitro and in vivo assays are required to investigate the mechanistic basis of invasion. This review will focus on in vitro and in vivo assays used to study invasion in HNSCC, with special emphasis on some of the latest assays to study HNSCC.

In vitro modeling of the neurovascular environment by coculturing adult human brain endothelial cells with human neural stem cells

Brain and vascular cells form a functionally integrated signalling network that is known as the neurovascular unit (NVU). The signalling (autocrine, paracrine and juxtacrine) between different elements of this unit, especially in humans, is difficult to disentangle in vivo. Developing representative in vitro models is therefore essential to better understand the cellular interactions that govern the neurovascular environment. We here describe a novel approach to assay these cellular interactions by combining a human adult cerebral microvascular endothelial cell line (hCMEC/D3) with a fetal ganglionic eminence-derived neural stem cell (hNSC) line. These cell lines provide abundant homogeneous populations of cells to produce a consistently reproducible in vitro model of endothelial morphogenesis and the ensuing NVU. Vasculature-like structures (VLS) interspersed with patches of differentiating neural cells only occurred when hNSCs were seeded onto a differentiated endothelium. These VLS emerged within 3 days of coculture and by day 6 were stabilizing. After 7 days of coculture, neuronal differentiation of hNSCs was increased 3-fold, but had no significant effect on astrocyte or oligodendrocyte differentiation. ZO1, a marker of adherens and tight junctions, was highly expressed in both undifferentiated and differentiated endothelial cells, but the adherens junction markers CD31 and VE-cadherin were significantly reduced in coculture by approximately 20%. A basement membrane, consisting of laminin, vitronectin, and collagen I and IV, separated the VLS from neural patches. This simple assay can assist in elucidating the cellular and molecular signaling involved in the formation of VLS, as well as the enhancement of neuronal differentiation through endothelial signaling.

Genetic drivers of metastatic dissemination in sonic hedgehog medulloblastoma

Leptomeningeal dissemination (LMD), the metastatic spread of tumor cells via the cerebrospinal fluid to the brain and spinal cord, is an ominous prognostic sign for patients with the pediatric brain tumor medulloblastoma. The need to reduce the risk of LMD has driven the development of aggressive treatment regimens, which cause disabling neurotoxic side effects in long-term survivors. Transposon-mediated mutagenesis studies in mice have revealed numerous candidate metastasis genes. Understanding how these genes drive LMD will require functional assessment using in vivo and cell culture models of medulloblastoma. We analyzed two genes that were sites of frequent transposon insertion and highly expressed in human medulloblastomas: Arnt (aryl hydrocarbon receptor nuclear translocator) and Gdi2 (GDP dissociation inhibitor 2). Here we show that ectopic expression of Arnt and Gdi2 promoted LMD in mice bearing Sonic hedgehog (Shh)-induced medulloblastomas. We overexpressed Arnt and Gdi2 in a human medulloblastoma cell line (DAOY) and an immortalized, nontransformed cell line derived from mouse granule neuron precursors (SHH-NPD) and quantified migration, invasiveness, and anchorage-independent growth, cell traits that are associated with metastatic competence in carcinomas. In SHH-NPD cells. Arnt and Gdi2 stimulated all three traits. In DAOY cells, Arnt had the same effects, but Gdi2 stimulated invasiveness only. These results support a mechanism whereby Arnt and Gdi2 cause cells to detach from the primary tumor mass by increasing cell motility and invasiveness. By conferring to tumor cells the ability to proliferate without surface attachment, Arnt and Gdi2 favor the formation of stable colonies of cells capable of seeding the leptomeninges.

Orchestration of angiogenesis by immune cells

It is widely accepted that the tumor microenvironment (TUMIC) plays a major role in cancer and is indispensable for tumor progression. The TUMIC involves many "players" going well beyond the malignant-transformed cells, including stromal, immune, and endothelial cells (ECs). The non-malignant cells can acquire tumor-promoting functions during carcinogenesis. In particular, these cells can "orchestrate" the "symphony" of the angiogenic switch, permitting the creation of new blood vessels that allows rapid expansion and progression toward malignancy. Considerable attention within the context of tumor angiogenesis should focus not only on the ECs, representing a fundamental unit, but also on immune cells and on the inflammatory tumor infiltrate. Immune cells infiltrating tumors typically show a tumor-induced polarization associated with attenuation of anti-tumor functions and generation of pro-tumor activities, among these angiogenesis. Here, we propose a scenario suggesting that the angiogenic switch is an immune switch arising from the pro-angiogenic polarization of immune cells. This view links immunity, inflammation, and angiogenesis to tumor progression. Here, we review the data in the literature and seek to identify the "conductors" of this "orchestra." We also suggest that interrupting the immune → inflammation → angiogenesis → tumor progression process can delay or prevent tumor insurgence and malignant disease.

Alternative splicing of the RAGE cytoplasmic domain regulates cell signaling and function

The Receptor for Advanced Glycation End-products (RAGE) is a multi-ligand receptor present on most cell types. Upregulation of RAGE is seen in a number of pathological states including, inflammatory and vascular disease, dementia, diabetes and various cancers. We previously demonstrated that alternative splicing of the RAGE gene is an important mechanism which regulates RAGE signaling through the production of soluble ligand decoy isoforms. However, no studies have identified any alternative splice variants within the intracellular region of RAGE, a region critical for RAGE signaling. Herein, we have cloned and characterized a novel splice variant of RAGE that has a truncated intracellular domain (RAGEΔICD). RAGEΔICD is prevalent in both human and mouse tissues including lung, brain, heart and kidney. Expression of RAGEΔICD in C6 glioma cells impaired RAGE-ligand induced signaling through various MAP kinase pathways including ERK1/2, p38 and SAPK/JNK. Moreover, RAGEΔICD significantly affected tumor cell properties through altering cell migration, invasion, adhesion and viability in C6 glioma cells. Furthermore, C6 glioma cells expressing RAGEΔICD exhibited drastic inhibition on tumorigenesis in soft agar assays. Taken together, these data indicate that RAGEΔICD represents a novel endogenous mechanism to regulate RAGE signaling. Significantly, RAGEΔICD could play an important role in RAGE related disease states through down regulation of RAGE signaling.

The neurotrophic factor neurturin contributes toward an aggressive cancer cell phenotype, neuropathic pain and neuronal plasticity in pancreatic cancer

Neurotrophic factors possess an emerging role in the pathophysiology of several gastrointestinal disorders, regulating innervation, pain sensation and disease-associated neuroplasticity. Here, we aimed at characterizing the role of the neurotrophic factor neurturin (NRTN) and its receptor glial-cell-line-derived neurotrophic factor receptor alpha-2 (GFRα-2) in pancreatic cancer (PCa) and pancreatic neuropathy. For this purpose, NRTN and GFRα-2 were studied in normal human pancreas and PCa tissues via immunohistochemistry, quantitative reverse transcription-polymerase chain reaction, immunoblotting and correlated to abdominal pain. The impact of NRTN/GFRα-2 on PCa cell (PCC) biology was investigated via exposure to hypoxia, 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyl tetrazolium bromide viability and matrigel invasion assays in native and specific small interfering RNA-silenced PCCs. To assess the influence of NRTN on pancreatic neuroplasticity and neural invasion (NI), its impact was explored via an in vitro 'neuroplasticity assay' and a 3D neural migration assay. NRTN and GFRα-2 demonstrated a site-specific upregulation in PCa, predominantly in nerves, PCCs and extracellular matrix. Patients with severe pain demonstrated higher intraneural GFRα-2 immunoreactivity than patients with no pain. PCa tissue and PCCs contained increased amounts of NRTN, which was suppressed under hypoxia. NRTN promoted PCC invasiveness, and silencing of NRTN limited both PCC proliferation and invasion. Depletion of NRTN from PCa tissue extracts and PCC supernatants decreased axonal sprouting in neuronal cultures but did not influence glial density. Silencing of NRTN in PCCs boosted NI. We conclude that increased NRTN/GFRα-2 in PCa seems to promote an aggressive PCC phenotype and neuroplasticity in PCa. Accelerated NI following NRTN suppression constitutes a novel explanation for the attraction of PCC to nerves in the hypoxic PCa tumor microenvironment.

SUMMARY

PCa is characterized by intrapancreatic neuroplasticity and NI. Here, we show that PCC produce the neurotrophic factor NRTN, which reinforces their biological properties, triggers neuroplastic alterations, NI and influences pain sensation via the GFRα-2 receptor.

The proangiogenic phenotype of natural killer cells in patients with non-small cell lung cancer

The tumor microenvironment can polarize innate immune cells to a proangiogenic phenotype. Decidual natural killer (dNK) cells show an angiogenic phenotype, yet the role for NK innate lymphoid cells in tumor angiogenesis remains to be defined. We investigated NK cells from patients with surgically resected non-small cell lung cancer (NSCLC) and controls using flow cytometric and functional analyses. The CD56(+)CD16(-) NK subset in NSCLC patients, which represents the predominant NK subset in tumors and a minor subset in adjacent lung and peripheral blood, was associated with vascular endothelial growth factor (VEGF), placental growth factor (PIGF), and interleukin-8 (IL-8)/CXCL8 production. Peripheral blood CD56(+)CD16(-) NK cells from patients with the squamous cell carcinoma (SCC) subtype showed higher VEGF and PlGF production compared to those from patients with adenocarcinoma (AdC) and controls. Higher IL-8 production was found for both SCC and AdC compared to controls. Supernatants derived from NSCLC CD56(+)CD16(-) NK cells induced endothelial cell chemotaxis and formation of capillary-like structures in vitro, particularly evident in SCC patients and absent from controls. Finally, exposure to transforming growth factor-β(1) (TGFβ(1)), a cytokine associated with dNK polarization, upregulated VEGF and PlGF in peripheral blood CD56(+)CD16(-) NK cells from healthy subjects. Our data suggest that NK cells in NSCLC act as proangiogenic cells, particularly evident for SCC and in part mediated by TGFβ(1).

Basement membrane-rich organoids with functional human blood vessels are permissive niches for human breast cancer metastasis

Metastatic breast cancer is the leading cause of death by malignancy in women worldwide. Tumor metastasis is a multistep process encompassing local invasion of cancer cells at primary tumor site, intravasation into the blood vessel, survival in systemic circulation, and extravasation across the endothelium to metastasize at a secondary site. However, only a small percentage of circulating cancer cells initiate metastatic colonies. This fact, together with the inaccessibility and structural complexity of target tissues has hampered the study of the later steps in cancer metastasis. In addition, most data are derived from in vivo models where critical steps such as intravasation/extravasation of human cancer cells are mediated by murine endothelial cells. Here, we developed a new mouse model to study the molecular and cellular mechanisms underlying late steps of the metastatic cascade. We have shown that a network of functional human blood vessels can be formed by co-implantation of human endothelial cells and mesenchymal cells, embedded within a reconstituted basement membrane-like matrix and inoculated subcutaneously into immunodeficient mice. The ability of circulating cancer cells to colonize these human vascularized organoids was next assessed in an orthotopic model of human breast cancer by bioluminescent imaging, molecular techniques and immunohistological analysis. We demonstrate that disseminated human breast cancer cells efficiently colonize organoids containing a functional microvessel network composed of human endothelial cells, connected to the mouse circulatory system. Human breast cancer cells could be clearly detected at different stages of the metastatic process: initial arrest in the human microvasculature, extravasation, and growth into avascular micrometastases. This new mouse model may help us to map the extravasation process with unprecedented detail, opening the way for the identification of relevant targets for therapeutic intervention.

Tissue engineering concept in the research of the tumor biology

Tumor is a heterogeneous complex, which lives in a three-dimensional environment flush with biopathophysiological and biomechanical signals. This signaling abundant extracellular milieu co-evolving from cell-cell and cell-host interaction guides the development and the generation of the tumor. There has been a recent surge of interest in studying the tumor biology that more closely mirror what happens in living organisms, especially in cancer research. Incorporating cancer cells in the 3D mimicking environment instead of monolayers is reasonable for maintaining in vivo cancer behaviors in spatial and temporal context. However, 3D culture for cancer still presents a challenge for researchers in this field. Tissue engineering, originally aiming at designing the artificial organs, provided a feasible approach to recreate such complex mechanical and biochemical interplay. Aside from reproducing bionic environment, tissue engineering has been routinely introduced into cancer study to build three dimensional structures not only to develop molecular therapeutics, but also to screen for toxic effects of drugs or radiotherapy sensitivity. In this article, we focused on the recent advances of the well-defined tissue-engineering biomaterials in the application in tumor biology. We also discussed the fabrications of the scaffolds from different materials, which might contribute to future cancer research.

Hepatocyte growth factor-loaded biomaterials for mesenchymal stem cell recruitment

Human adult mesenchymal stem cells (MSC) can be readily harvested from bone marrow through aspiration. MSC are involved in tissue regeneration and repair, particularly in wound healing. Due to their high self-renewal capacity and excellent differentiation potential in vitro, MSC are ideally suited for regenerative medicine. The complex interactions of MSC with their environment and their influence on the molecular and functional levels are widely studied but not completely understood. MSC secrete, for example, hepatocyte growth factor (HGF), whose concentration is enhanced in wounded areas and which is shown to act as a chemoattractant for MSC. We produced HGF-loaded biomaterials based on collagen and fibrin gels to develop a recruitment system for endogenous MSC to improve wound healing. Here, we report that HGF incorporated into collagen or fibrin gels leads to enhanced and directed MSC migration in vitro. HGF-loaded biomaterials might be potentially used as in vivo wound dressings to recruit endogenous MSC from tissue-specific niches towards the wounded area. This novel approach may help to reduce costly multistep procedures of cell isolation, in vitro culture, and transplantation usually used in tissue engineering.

Two-dimensional vs. three-dimensional in vitro tumor migration and invasion assays

Motility and invasion are key hallmarks that distinguish benign from malignant tumors, enabling cells to cross tissue boundaries, disseminate in blood and lymph and establish metastases at distant sites. Similar properties are also utilized by activated endothelial cells during tumor-induced angiogenesis. It is now appreciated that these processes might provide a rich source of novel molecular targets with the potential for inhibitors to restrain both metastasis and neoangiogenesis. Such therapeutic strategies require assays that can rapidly and quantitatively measure cell movement and the ability to traverse physiological barriers. The need for high-throughput, however, must be balanced by assay designs that accommodate, as far as possible, the complexity of the in vivo tumor microenvironment. This chapter aims to give an overview of some commonly used migration and invasion assays to aid in the selection of a balanced portfolio of techniques for the rapid and accurate evaluation of novel therapeutic agents.

Protein composition and biomechanical properties of in vivo-derived basement membranes

Basement membranes (BMs) evolved together with the first metazoan species approximately 500 million years ago. Main functions of BMs are stabilizing epithelial cell layers and connecting different types of tissues to functional, multicellular organisms. Mutations of BM proteins from worms to humans are either embryonic lethal or result in severe diseases, including muscular dystrophy, blindness, deafness, kidney defects, cardio-vascular abnormalities or retinal and cortical malformations. In vivo-derived BMs are difficult to come by; they are very thin and sticky and, therefore, difficult to handle and probe. In addition, BMs are difficult to solubilize complicating their biochemical analysis. For these reasons, most of our knowledge of BM biology is based on studies of the BM-like extracellular matrix (ECM) of mouse yolk sac tumors or from studies of the lens capsule, an unusually thick BM. Recently, isolation procedures for a variety of BMs have been described, and new techniques have been developed to directly analyze the protein compositions, the biomechanical properties and the biological functions of BMs. New findings show that native BMs consist of approximately 20 proteins. BMs are four times thicker than previously recorded, and proteoglycans are mainly responsible to determine the thickness of BMs by binding large quantities of water to the matrix. The mechanical stiffness of BMs is similar to that of articular cartilage. In mice with mutation of BM proteins, the stiffness of BMs is often reduced. As a consequence, these BMs rupture due to mechanical instability explaining many of the pathological phenotypes. Finally, the morphology and protein composition of human BMs changes with age, thus BMs are dynamic in their structure, composition and biomechanical properties.

M6P/IGF2R modulates the invasiveness of liver cells via its capacity to bind mannose 6-phosphate residues

BACKGROUND & AIMS

The mannose 6-phosphate/insulin-like growth factor II receptor (M6P/IGF2R), a multifunctional protein, plays a central role in intracellular targeting of lysosomal enzymes and control of insulin-like growth factor II (IGF-II) bioactivity. Importantly, the gene encoding this receptor is frequently inactivated in a wide range of malignant tumors including hepatocellular carcinomas. Thus, M6P/IGF2R is considered a putative liver tumor suppressor. The aim of this study was to establish the impact of the receptor on the invasive properties of liver cells.

METHODS

Reconstitution experiments were performed by expression of wild type and mutant M6P/IGF2R in receptor-deficient FRL14 fetal rat liver cells. RNA interference was used to induce M6P/IGF2R downregulation in receptor-positive MIM-1-4 mouse hepatocytes.

RESULTS

We show that the M6P/IGF2R status exerts a strong impact on the invasiveness of tumorigenic rodent liver cells. M6P/IGF2R-deficient fetal rat liver cells hypersecrete lysosomal cathepsins and penetrate extracellular matrix barriers in a cathepsin-dependent manner. Forced expression of M6P/IGF2R restores intracellular transport of cathepsins to lysosomes and concomitantly reduces the tumorigenicity and invasive potential of these cells. Conversely, M6P/IGF2R knock-down in receptor-positive mouse hepatocytes causes increased cathepsin secretion as well as enhanced cell motility and invasiveness. We also demonstrate that functional M6P-binding sites are important for the anti-invasive properties of M6P/IGF2R, whereas the capacity to bind IGF-II is dispensable for the anti-invasive activity of the receptor in liver cells.

CONCLUSIONS

M6P/IGF2R restricts liver cell invasion by preventing the pericellular action of M6P-modified proteins.

Cancer prevention by targeting angiogenesis

Healthy individuals can harbour microscopic tumours and dysplastic foci in different organs in an undetectable and asymptomatic state for many years. These lesions do not progress in the absence of angiogenesis or inflammation. Targeting both processes before clinical manifestation can prevent tumour growth and progression. Angioprevention is a chemoprevention approach that interrupts the formation of new blood vessels when tumour cell foci are in an indolent state. Many efficacious chemopreventive drugs function by preventing angiogenesis in the tumour microenvironment. Blocking the vascularization of incipient tumours should maintain a dormancy state such that neoplasia or cancer exist without disease. The current limitations of antiangiogenic cancer therapy may well be related to the use of antiangiogenic agents too late in the disease course. In this Review, we suggest mechanisms and strategies for using antiangiogenesis agents in a safe, preventive clinical angioprevention setting, proposing different levels of clinical angioprevention according to risk, and indicate potential drugs to be employed at these levels. Finally, angioprevention may go well beyond cancer in the prevention of a range of chronic disorders where angiogenesis is crucial, including different forms of inflammatory or autoimmune diseases, ocular disorders, and neurodegeneration.

Human lung cancer cells grown on acellular rat lung matrix create perfusable tumor nodules

BACKGROUND

Extracellular matrix allows lung cancer to form its shape and grow. Recent studies on organ reengineering for orthotopic transplantation have provided a new avenue for isolating purified native matrix to use for growing cells. Whether human lung cancer cells grown in a decellularized rat lung matrix would create perfusable human lung cancer nodules was tested.

METHODS

Rat lungs were harvested and native cells were removed using sodium dodecyl sulfate and Triton X-100 in a decellularization chamber to create a decellularized rat lung matrix. Human A549, H460, or H1299 lung cancer cells were placed into the decellularized rat lung matrix and grown in a customized bioreactor with perfusion of oxygenated media for 7 to 14 days.

RESULTS

Decellularized rat lung matrix showed preservation of matrix architecture devoid of all rat cells. All three human lung cancer cell lines grown in the bioreactor developed tumor nodules with intact vasculature. Moreover, the lung cancer cells developed a pattern of growth similar to the original human lung cancer.

CONCLUSIONS

Overall, this study shows that human lung cancer cells form perfusable tumor nodules in a customized bioreactor on a decellularized rat lung matrix created by a customized decellularization chamber. The lung cancer cells grown in the matrix had features similar to the original human lung cancer. This ex vivo model can be used potentially to gain a deeper understanding of the biologic processes involved in human lung cancer.

MRI of metastasis-permissive microenvironments

One of the earliest documented observations of the importance of the microenvironment in metastasis was made by Stephen Paget in 1889. More than a century later, the metastatic cascade remains a major cause of mortality from cancer. Cancer meets the criterion of a successful organization that is able to survive by adapting to changing environments. In fact, the tumor microenvironment and stroma are co-opted and shaped by cancer cells to derive a survival advantage. Cohesive strategies integrating advances in molecular biology and chemistry, with noninvasive multimodality imaging, provide new insights into the role of the tumor microenvironment in promoting metastasis from primary tumors as well as insights into environments that attract and permit cancer cells to establish colonies in distant organs. This article provides an overview of molecular and functional imaging characterization of microenvironments that can promote or permit cancer cells to metastasize and the microenvironmental characteristics of distant metastases.

Streptococci-human papilloma virus interaction with ethanol exposure leads to keratinocyte damage

PURPOSE

Ethanol, human papilloma virus (HPV), and poor oral hygiene are risk factors that have been attributed to oral carcinogenesis. Streptococci sp and HPV infections are common in the head and neck, often associated with sexual activity. Although HPV is linked to head and neck squamous cell carcinoma, it is unclear whether there is a similar role for Streptococci sp. This cell study examines whether Streptococci sp and HPV-16 with exposure to ethyl alcohol (ETOH) can act as cofactors in the malignant transformation of oral keratinocytes.

MATERIALS AND METHODS

ETOH (0.1%-20% vol/vol) was used to investigate Streptococci sp attachment with immortalized E6-expressing HPV/HOK-16B cells, human oral buccal keratinocytes, and foreskin keratinocytes. Streptococci sp (Streptococci mutans [LT11]) and various strains of acetaldehyde (AA) producer and nonproducer Streptococcus salivarius (110-1, 109-2, 101-7, and 107-1) and a lactic acid producer bacterium, Lactobacillus rhamnosus (24-1 and 25-2), were examined for interactions with keratinocytes by use of a green dye (percent of cells with colonies after 24 hours). Carcinogens, AA, malondialdehyde, DNA damage, and proliferation (5'-bromo-2-deoxyuridine) among keratinocytes were also quantified.

RESULTS

AA and malondialdehyde production from permissible Streptococci sp significantly increased with attachment to keratinocytes, whereas L rhamnosus did not significantly attach to keratinocytes. This attachment was associated with enhanced levels of AA adduct formation, proliferation (5'-bromo-2-deoxyuridine incorporation), and enhanced migration through integrin-coated basement membrane by HPV oral keratinocytes, which are characteristics of a malignant phenotype.

CONCLUSIONS

These cell studies suggest that oral Streptococci sp and HPV (HPV-16) cooperate to transform oral keratinocytes after low-level ETOH (1%) exposure. These results appear to suggest a significant clinical interaction, but further validation is warranted.