Chemotaxis in cancer

Polymorphism of FGD4 and myelosuppression in patients with esophageal squamous cell carcinoma

Background: Chemotherapy-related adverse events may restrain taxane/cisplatin administration as a regimen for patients with esophageal squamous cell carcinoma. Genetic polymorphisms may contribute to adverse event susceptibility. Method & results: The authors genotyped ten SNPs from five genes (rs1045642, rs2032582 and rs3213619 of ABCB1; rs2231137 and rs2231142 of ABCG2; rs246221 of ABCC1; rs3740066 of ABCC2; and rs10771973, rs12296975 and rs1239829 of FGD4) in 219 patients with esophageal squamous cell carcinoma treated with taxane/cisplatin. Patients with severe toxicities were compared with those with minor or no adverse events by unconditional logistic regression models and semi-Bayesian shrinkage. After adjustment for age and sex, with the null prior, FGD4 rs1239829 was statistically significantly related to grade 3-4 leukopenia (odds ratio [95% CI] in dominant model = 1.77 [1.04-3.03]). Conclusion: The minor allele of FGD4 rs1239829 was related to grade 3-4 leukopenia in patients with esophageal squamous cell carcinoma treated with taxane/cisplatin, with unclear biological mechanism.

The epithelial-mesenchymal transition and the cytoskeleton in bioengineered systems

The epithelial-mesenchymal transition (EMT) is intrinsically linked to alterations of the intracellular cytoskeleton and the extracellular matrix. After EMT, cells acquire an elongated morphology with front/back polarity, which can be attributed to actin-driven protrusion formation as well as the gain of vimentin expression. Consequently, cells can deform and remodel the surrounding matrix in order to facilitate local invasion. In this review, we highlight recent bioengineering approaches to elucidate EMT and functional changes in the cytoskeleton. First, we review transitions between multicellular clusters and dispersed individuals on planar surfaces, which often exhibit coordinated behaviors driven by leader cells and EMT. Second, we consider the functional role of vimentin, which can be probed at subcellular length scales and within confined spaces. Third, we discuss the role of topographical patterning and EMT via a contact guidance like mechanism. Finally, we address how multicellular clusters disorganize and disseminate in 3D matrix. These new technologies enable controlled physical microenvironments and higher-resolution spatiotemporal measurements of EMT at the single cell level. In closing, we consider future directions for the field and outstanding questions regarding EMT and the cytoskeleton for human cancer progression. Video Abstract.

State of the art of bacterial chemotaxis

Bacterial chemotaxis is a biased movement of bacteria toward the beneficial chemical gradient or away from a toxic chemical gradient. This movement is achieved by sensing a chemical gradient by chemoreceptors. In most of the chemotaxis studies, Escherichia coli has been used as a model organism. E. coli have about 4-6 flagella on their surfaces, and the motility is achieved by rotating the flagella. Each flagellum has reversible flagellar motors at its base, which rotate the flagella in counterclockwise and clockwise directions to achieve "run" and "tumble." The chemotaxis of bacteria is regulated by a network of interacting proteins. The sensory signal is processed and transmitted to the flagellar motor by cytoplasmic proteins. Bacterial chemotaxis plays an important role in many biological processes such as biofilm formation, quorum sensing, bacterial pathogenesis, and host infection. Bacterial chemotaxis can be applied for bioremediation, horizontal gene transfer, drug delivery, or maybe some other industry in near future. This review contains an overview of bacterial chemotaxis, recent findings of the physiological importance of bacterial chemotaxis in other biological processes, and the application of bacterial chemotaxis.

Visualizing cancer extravasation: from mechanistic studies to drug development

Metastasis is a multistep process that accounts for the majority of cancer-related death. By the end of metastasize dissemination, circulating tumor cells (CTC) need to extravasate the blood vessels at metastatic sites to form new colonization. Although cancer cell extravasation is a crucial step in cancer metastasis, it has not been successfully targeted by current anti-metastasis strategies due to the lack of a thorough understanding of the molecular mechanisms that regulate this process. This review focuses on recent progress in cancer extravasation visualization techniques, including the development of both in vitro and in vivo cancer extravasation models, that shed light on the underlying mechanisms. Specifically, multiple cancer extravasation stages, such as the adhesion to the endothelium and transendothelial migration, are successfully probed using these technologies. Moreover, the roles of different cell adhesive molecules, chemokines, and growth factors, as well as the mechanical factors in these stages are well illustrated. Deeper understandings of cancer extravasation mechanisms offer us new opportunities to escalate the discovery of anti-extravasation drugs and therapies and improve the prognosis of cancer patients.

Human Costars Family Protein ABRACL Modulates Actin Dynamics and Cell Migration and Associates with Tumorigenic Growth

Regulation of cellular actin dynamics is pivotal in driving cell motility. During cancer development, cells migrate to invade and spread; therefore, dysregulation of actin regulators is often associated with cancer progression. Here we report the role of ABRACL, a human homolog of the Dictyostelium actin regulator Costars, in migration and tumorigenic growth of cancer cells. We found a correlation between ABRACL expression and the migratory ability of cancer cells. Cell staining revealed the colocalization of ABRACL and F-actin signals at the leading edge of migrating cells. Analysis of the relative F-/G-actin contents in cells lacking or overexpressing ABRACL suggested that ABRACL promotes cellular actin distribution to the polymerized fraction. Physical interaction between ABRACL and cofilin was supported by immunofluorescence staining and proximity ligation. Additionally, ABRACL hindered cofilin-simulated pyrene F-actin fluorescence decay in vitro, indicating a functional interplay. Lastly, analysis on a colorectal cancer cohort demonstrated that high ABRACL expression was associated with distant metastasis, and further exploration showed that depletion of ABRACL expression in colon cancer cells resulted in reduced cell proliferation and tumorigenic growth. Together, results suggest that ABRACL modulates actin dynamics through its interaction with cofilin and thereby regulates cancer cell migration and participates in cancer pathogenesis.

The Chemokine Receptor CCR3 Is Potentially Involved in the Homing of Prostate Cancer Cells to Bone: Implication of Bone-Marrow Adipocytes

Bone metastasis remains the most frequent and the deadliest complication of prostate cancer (PCa). Mechanisms leading to the homing of tumor cells to bone remain poorly characterized. Role of chemokines in providing navigational cues to migrating cancer cells bearing specific receptors is well established. Bone is an adipocyte-rich organ since 50 to 70% of the adult bone marrow (BM) volume comprise bone marrow adipocytes (BM-Ads), which are likely to produce chemokines within the bone microenvironment. Using in vitro migration assays, we demonstrated that soluble factors released by human primary BM-Ads are able to support the directed migration of PCa cells in a CCR3-dependent manner. In addition, we showed that CCL7, a chemokine previously involved in the CCR3-dependent migration of PCa cells outside of the prostate gland, is released by human BM-Ads. These effects are amplified by obesity and ageing, two clinical conditions known to promote aggressive and metastatic PCa. In human tumors, we found an enrichment of CCR3 in bone metastasis vs. primary tumors at mRNA levels using Oncomine microarray database. In addition, immunohistochemistry experiments demonstrated overexpression of CCR3 in bone versus visceral metastases. These results underline the potential importance of BM-Ads in the bone metastatic process and imply a CCR3/CCL7 axis whose pharmacological interest needs to be evaluated.

Myeloid cells: Prime drivers of tumor progression

Metastasis is a key step in cancer progression, and was traditionally attributed to the accumulation of genetic and epigenetic changes within individual cancer cells. These changes promoted invasiveness, immune evasion and survival at distant sites. However, recent studies reveal that metastasis is not achieved by the cancer cell in isolation, but requires intervention from the immune system. The myeloid cell population in particular is now implicated in many aspects of metastasis. Here, we bring together the evidence for the importance of various myeloid cell sub-populations throughout the metastatic process, from initiation of cancer cell invasiveness, to priming the tissue site for colonization.

Role of neutrophil extracellular traps in regulation of lung cancer invasion and metastasis: Structural insights from a computational model

Lung cancer is one of the leading causes of cancer-related deaths worldwide and is characterized by hijacking immune system for active growth and aggressive metastasis. Neutrophils, which in their original form should establish immune activities to the tumor as a first line of defense, are undermined by tumor cells to promote tumor invasion in several ways. In this study, we investigate the mutual interactions between the tumor cells and the neutrophils that facilitate tumor invasion by developing a mathematical model that involves taxis-reaction-diffusion equations for the critical components in the interaction. These include the densities of tumor and neutrophils, and the concentrations of signaling molecules and structure such as neutrophil extracellular traps (NETs). We apply the mathematical model to a Boyden invasion assay used in the experiments to demonstrate that the tumor-associated neutrophils can enhance tumor cell invasion by secreting the neutrophil elastase. We show that the model can both reproduce the major experimental observation on NET-mediated cancer invasion and make several important predictions to guide future experiments with the goal of the development of new anti-tumor strategies. Moreover, using this model, we investigate the fundamental mechanism of NET-mediated invasion of cancer cells and the impact of internal and external heterogeneity on the migration patterning of tumour cells and their response to different treatment schedules.

Heterogeneity in 2,6-Linked Sialic Acids Potentiates Invasion of Breast Cancer Epithelia

Heterogeneity in phenotypes of malignantly transformed cells and aberrant glycan expression on their surface are two prominent hallmarks of cancers that have hitherto not been linked to each other. In this paper, we identify differential levels of a specific glycan linkage: α2,6-linked sialic acids within breast cancer cells in vivo and in culture. Upon sorting out two populations with moderate, and relatively higher, cell surface α2,6-linked sialic acid levels from the triple-negative breast cancer cell line MDA-MB-231, both populations (denoted as medium and high 2,6-Sial cells, respectively) stably retained their levels in early passages. Upon continuous culturing, medium 2,6-Sial cells recapitulated the heterogeneity of the unsorted line whereas high 2,6-Sial cells showed no such tendency. Compared with high 2,6-Sial cells, the medium 2,6-Sial counterparts showed greater adhesion to reconstituted extracellular matrices (ECMs) and invaded faster as single cells. The level of α2,6-linked sialic acids in the two sublines was found to be consistent with the expression of a specific glycosyl transferase, ST6GAL1. Stably knocking down ST6GAL1 in the high 2,6-Sial cells enhanced their invasiveness. When cultured together, medium 2,6-Sial cells differentially migrated to the edge of growing tumoroid-like cocultures, whereas high 2,6-Sial cells formed the central bulk. Multiscale simulations in a Cellular Potts model-based computational environment calibrated to our experimental findings suggest that differential levels of cell-ECM adhesion, likely regulated by α2,6-linked sialic acids, facilitate niches of highly invasive cells to efficiently migrate centrifugally as the invasive front of a malignant breast tumor.

Identifying Discriminative Biological Function Features and Rules for Cancer-Related Long Non-coding RNAs

Cancer has been a major public health problem worldwide for many centuries. Cancer is a complex disease associated with accumulative genetic mutations, epigenetic aberrations, chromosomal instability, and expression alteration. Increasing lines of evidence suggest that many non-coding transcripts, which are termed as non-coding RNAs, have important regulatory roles in cancer. In particular, long non-coding RNAs (lncRNAs) play crucial roles in tumorigenesis. Cancer-related lncRNAs serve as oncogenic factors or tumor suppressors. Although many lncRNAs are identified as potential regulators in tumorigenesis by using traditional experimental methods, they are time consuming and expensive considering the tremendous amount of lncRNAs needed. Thus, effective and fast approaches to recognize tumor-related lncRNAs should be developed. The proposed approach should help us understand not only the mechanisms of lncRNAs that participate in tumorigenesis but also their satisfactory performance in distinguishing cancer-related lncRNAs. In this study, we utilized a decision tree (DT), a type of rule learning algorithm, to investigate cancer-related lncRNAs with functional annotation contents [gene ontology (GO) terms and KEGG pathways] of their co-expressed genes. Cancer-related and other lncRNAs encoded by the key enrichment features of GO and KEGG filtered by feature selection methods were used to build an informative DT, which further induced several decision rules. The rules provided not only a new tool for identifying cancer-related lncRNAs but also connected the lncRNAs and cancers with the combinations of GO terms. Results provided new directions for understanding cancer-related lncRNAs.

Gβγ recruits and activates P-Rex1 via two independent binding interfaces

Gβγ marks the inner side of the plasma membrane where chemotactic GPCRs activate Rac to lead the assembly of actin filaments that push the cell to move forward. Upon dissociation from heterotrimeric Gi, Gβγ recruits and activates P-Rex1, a Rac guanine nucleotide exchange factor (RacGEF). This cytosolic chemotactic effector is kept inactive by intramolecular interactions. The mechanism by which Gβγ stimulates P-Rex1 has been debated. We hypothesized that Gβγ activates P-Rex1 by a two-step mechanism based on independent interaction interfaces to recruit and unroll this RacGEF. Using pulldown assays, we found that Gβγ binds P-Rex1-DH/PH as well as PDZ-PDZ domains. These domains and the DEP-DEP tandem interact among them and dissociate upon binding with Gβγ, arguing for a stimulatory allosteric effect. In addition, P-Rex1 catalytic activity is inhibited by its C-terminal domain. To discern P-Rex1 recruitment from activation, we studied Q-Rhox, a synthetic RhoGEF having the PDZ-RhoGEF catalytic DH/PH module, insensitive to Gβγ, swapped into P-Rex1. Gβγ recruited Q-Rhox to the plasma membrane, indicating that Gβγ/PDZ-PDZ interaction interface plays a role on P-Rex1 recruitment. In conclusion, we reconcile previous findings and propose a mechanistic model of P-Rex1 activation; accordingly, Gβγ recruits P-Rex1 via the Gβγ/PDZ-PDZ interface followed by a second contact involving the Gβγ/DH/PH interface to unleash P-Rex1 RacGEF activity at the plasma membrane.

A Journey of Nanomotors for Targeted Cancer Therapy: Principles, Challenges, and a Critical Review of the State-of-the-Art

A nanomotor is a miniaturized device that converts energy stored in the environment into mechanical motion. The last two decades have witnessed a surge of research interests in the biomedical applications of nanomotors, but little clinical translation. To accelerate this process, targeted cancer therapy is used as an example to describe a "survive, locate, operate, and terminate" (SLOT) mission of a nanomotor, where it must 1) survive in the unfriendly in vivo environment, 2) locate its target as well as be located by human operators, 3) carry out specific operations, and 4) terminate after the mission is completed. Along this journey, the challenges presented to a nanomotor, including to power, navigate, steer, target, release, control, image, and communicate are discussed, and how state-of-the-art nanomotors meet or fall short of these requirements is critically reviewed. These discussions are then condensed into a table for easy reference. In particular, it is argued that chemically powered nanomotors are intrinsically ill-positioned for targeted cancer therapy, while nanomotors powered by magnetic fields or ultrasound show more promises. Following this argument, a tentative nanomotor design is then presented in the end to conform to the SLOT guideline, and to inspire practical, functional nanorobots that are yet to come.

Dictyostelium discoideum as a non-mammalian biomedical model

Dictyostelium discoideum is one of eight non-mammalian model organisms recognized by the National Institute of Health for the study of human pathology. The use of this slime mould is possible owing to similarities in cell structure, behaviour and intracellular signalling with mammalian cells. Its haploid set of chromosomes completely sequenced amenable to genetic manipulation, its unique and short life cycle with unicellular and multicellular stages, and phenotypic richness encoding many human orthologues, make Dictyostelium a representative and simple model organism to unveil cellular processes in human disease. Dictyostelium studies within the biomedical field have provided fundamental knowledge in the areas of bacterial infection, immune cell chemotaxis, autophagy/phagocytosis and mitochondrial and neurological disorders. Consequently, Dictyostelium has been used to the development of related pharmacological treatments. Herein, we review the utilization of Dictyostelium as a model organism in biomedicine.

Squeezing through the microcirculation: survival adaptations of circulating tumour cells to seed metastasis

During metastasis, tumour cells navigating the vascular circulatory system-circulating tumour cells (CTCs)-encounter capillary beds, where they start the process of extravasation. Biomechanical constriction forces exerted by the microcirculation compromise the survival of tumour cells within capillaries, but a proportion of CTCs manage to successfully extravasate and colonise distant sites. Despite the profound importance of this step in the progression of metastatic cancers, the factors about this deadly minority of cells remain elusive. Growing evidence suggests that mechanical forces exerted by the capillaries might induce adaptive mechanisms in CTCs, enhancing their survival and metastatic potency. Advances in microfluidics have enabled a better understanding of the cell-survival capabilities adopted in capillary-mimicking constrictions. In this review, we will highlight adaptations developed by CTCs to endure mechanical constraints in the microvasculature and outline how these mechanical forces might trigger dynamic changes towards a more invasive phenotype. A better understanding of the dynamic mechanisms adopted by CTCs within the microcirculation that ultimately lead to metastasis could open up novel therapeutic avenues.

Breast Cancer Metastasis

Owing to increased awareness of the importance of mammogram and advances in surgical technology, survival rate of patients with primary breast cancer has dramatically increased. Despite all these advances in breast cancer treatment, there are no currently available treatments for this disease once it metastasizes to distant organs including bones, lungs, brain, and liver. This is mainly attributed to the complexity of metastatic process. Recent advances in technology enabled cancer biologists to dissect each step of the metastatic process, and this led to discovery of major players and molecules in this process. In this section, we will discuss recent discovery and advances in the field of breast cancer metastasis research.

Cellular memory in eukaryotic chemotaxis depends on the background chemoattractant concentration

Cells of the social amoeba Dictyostelium discoideum migrate to a source of periodic traveling waves of chemoattractant as part of a self-organized aggregation process. An important part of this process is cellular memory, which enables cells to respond to the front of the wave and ignore the downward gradient in the back of the wave. During this aggregation, the background concentration of the chemoattractant gradually rises. In our microfluidic experiments, we exogenously applied periodic waves of chemoattractant with various background levels. We find that increasing background does not make detection of the wave more difficult, as would be naively expected. Instead, we see that the chemotactic efficiency significantly increases for intermediate values of the background concentration but decreases to almost zero for large values in a switch-like manner. These results are consistent with a computational model that contains a bistable memory module, along with a nonadaptive component. Within this model, an intermediate background level helps preserve directed migration by keeping the memory activated, but when the background level is higher, the directional stimulus from the wave is no longer sufficient to activate the bistable memory, suppressing directed migration. These results suggest that raising levels of chemoattractant background may facilitate the self-organized aggregation in Dictyostelium colonies.

Advances in understanding and in multi-disciplinary methodology used to assess lipid regulation of signalling cascades from the cancer cell plasma membrane

The lipid bilayer is a functional component of cells, forming a stable platform for the initiation of key biological processes, including cell signalling. There are distinct changes in the lipid composition of cell membranes during oncogenic transformation resulting in aberrant activation and inactivation of signalling transduction pathways. Studying the role of the cell membrane in cell signalling is challenging, since techniques are often limited to by timescale, resolution, sensitivity, and averaging. To overcome these limitations, combining 'computational', 'wet-lab' and 'semi-dry' approaches offers the best opportunity to resolving complex biological processes involved in membrane organisation. In this review, we highlight analytical tools that have been applied for the study of cell signalling initiation from the cancer cell membranes through computational microscopy, biological assays, and membrane biophysics. The cancer therapeutic potential of extracellular membrane-modulating agents, such as cholesterol-reducing agents is also discussed, as is the need for future collaborative inter-disciplinary research for studying the role of the cell membrane and its components in cancer therapy.

Actin dynamics during tumor cell dissemination

The actin cytoskeleton is a dynamic network that regulates cellular behavior from development to disease. By rearranging the actin cytoskeleton, cells are capable of migrating and invading during developmental processes; however, many of these cellular properties are hijacked by cancer cells to escape primary tumors and disseminate to distant organs in the body. In this review article, we highlight recent work describing how cancer cells regulate the actin cytoskeleton to achieve efficient invasion and metastatic colonization. We also review new imaging technologies that are capable of revealing the complex architecture and regulation of the actin cytoskeleton during motility and invasion of tumor cells.

Computational models of migration modes improve our understanding of metastasis

Tumor cells migrate through changing microenvironments of diseased and healthy tissue, making their migration particularly challenging to describe. To better understand this process, computational models have been developed for both the ameboid and mesenchymal modes of cell migration. Here, we review various approaches that have been used to account for the physical environment's effect on cell migration in computational models, with a focus on their application to understanding cancer metastasis and the related phenomenon of durotaxis. We then discuss how mesenchymal migration models typically simulate complex cell–extracellular matrix (ECM) interactions, while ameboid migration models use a cell-focused approach that largely ignores ECM when not acting as a physical barrier. This approach greatly simplifies or ignores the mechanosensing ability of ameboid migrating cells and should be reevaluated in future models. We conclude by describing future model elements that have not been included to date but would enhance model accuracy.

Tumor-Resident Stromal Cells Promote Breast Cancer Invasion through Regulation of the Basal Phenotype

Collective invasion can be led by breast cancer cells expressing basal epithelial markers, typified by keratin-14 (KRT14). We analyzed gene expression data from The Cancer Genome Atlas and demonstrated a significant correlation between a KRT14+ invasion signature and a stromal-mediated extracellular matrix (ECM) organization module. We then developed a novel coculture model of tumor organoids with autologous stromal cells. Coculture significantly increased KRT14 expression and invasion of organoids from both luminal and basal murine breast cancer models. However, stromal cell conditioned medium induced invasion but not KRT14 expression. Cancer cells released TGFβ and that signaling pathway was required for stromal cell-induced invasion and KRT14 expression. Mechanistically, TGFβ induced NOX4 expression in stromal cells and NOX4 inhibition reduced invasion and KRT14 expression. In summary, we developed a novel coculture model and revealed dynamic molecular interactions between stromal cells and cancer cells that regulate both basal gene expression and invasive behavior. IMPLICATIONS: Fibroblasts within mammary tumors can regulate the molecular phenotype and invasive behavior of breast cancer cells. VISUAL OVERVIEW: http://mcr.aacrjournals.org/content/molcanres/18/11/1615/F1.large.jpg.

The architecture of co-culture spheroids regulates tumor invasion within a 3D extracellular matrix

Tumor invasion, the process by which tumor cells break away from their primary tumor and gain access to vascular systems, is an important step in cancer metastasis. Most current 3D tumor invasion assays consisted of single tumor cells embedded within an extracellular matrix (ECM). These assays taught us much of what we know today on how key biophysical (e.g. ECM stiffness) and biochemical (e.g. cytokine gradients) parameters within the tumor microenvironment guided and regulated tumor invasion. One limitation of the single tumor cell invasion assay was that it did not account for cell-cell adhesion within the tumor. In this article, we developed a micrometer scale 3D co-culture spheroid invasion assay that was compatible with microscopic imaging. Micrometer scale co-culture spheroids (1:1 ratio of metastatic breast cancer MDA-MB-231 and non-tumorigenic epithelial MCF-10A cells) were made using an array of microwells, and then were embedded within a collagen matrix in a microfluidic platform. Real time imaging of tumor spheroid invasion revealed that the spatial distribution of the two cell types within the tumor spheroid critically regulated tumor invasion. This work linked tumor architecture with tumor invasion and highlighted the importance of the biophysical cues within the bulk of the tumor in tumor invasion.

MicroRNA-340-5p inhibits colon cancer cell migration via targeting of RhoA

Colon cancer is the third most common cancer and a significant cause of cancer-related deaths worldwide. Metastasis is the most insidious aspect of cancer progression. Convincing data suggest that microRNAs (miRs) play a key function in colon cancer biology. We examined the role of miR-340-5p in regulating RhoA expression as well as cell migration and invasion in colon cancer cells. Levels of miR-340-5p and RhoA mRNA varied inversely in serum-free and serum-grown HT-29 and AZ-97 colon cancer cells. It was found transfection with miR-340-5p not only decreased expression of RhoA mRNA and protein levels in HT-29 cells but also reduced colon cancer cell migration and invasion. Bioinformatics analysis predicted one putative binding sites at the 3'-UTR of RhoA mRNA. Targeting this binding site with a specific blocker reversed mimic miR-340-5p-induced inhibition of RhoA activation and colon cancer cell migration and invasion. These novel results suggest that miR-340-5p is an important regulator of colon cancer cell motility via targeting of RhoA and further experiments are warranted to evaluate the role of miR-340-5p in colon cancer metastasis.

Interleukin-8: A chemokine at the intersection of cancer plasticity, angiogenesis, and immune suppression

Tumor progression relies on the ability of cancer cells to effectively invade surrounding tissues and propagate. Among the many mechanisms that contribute to tumor progression is the epithelial-to-mesenchymal transition (EMT), a phenotypic plasticity phenomenon that increases the cancer cells' motility and invasiveness and influences their surrounding microenvironment by promoting the secretion of a variety of soluble factors. One such factor is IL-8, a chemokine with multiple pro-tumorigenic roles within the tumor microenvironment (TME), including stimulating proliferation or transformation of tumor cells into a migratory or mesenchymal phenotype. Further, IL-8 can increase tumor angiogenesis or recruit larger numbers of immunosuppressive cells to the tumor. Prognostically, observations in many tumor types show that patients with higher levels of IL-8 at baseline experience worse clinical outcomes. Additionally, studies have shown that the chemokine directly contributes to the development of resistance to both chemotherapy and molecularly targeted agents. More recently, clinical studies evaluating levels of IL-8 in patients receiving immune checkpoint inhibition (ICI) therapy deduced that myeloid tumor infiltration driven by IL-8 contributes to resistance to ICI agents and that peripheral IL-8 can predict outcomes to ICI therapy. Further, pre-clinical data demonstrate that targeting IL-8 or its receptors enables improved tumor killing by immune cells, and treatment strategies combining blockade of the IL-8/IL-8R axis with ICI ultimately improve anti-tumor efficacy. Based on these results and the prognostic capacity of IL-8, there are a number of ongoing clinical trials evaluating the addition of IL-8 targeting strategies to immune-based therapies.

All Roads Lead to Directional Cell Migration

Directional cell migration normally relies on a variety of external signals, such as chemical, mechanical, or electrical, which instruct cells in which direction to move. Many of the major molecular and physical effects derived from these cues are now understood, leading to questions about whether directional cell migration is alike or distinct under these different signals, and how cells might be directed by multiple simultaneous cues, which would be expected in complex in vivo environments. In this review, we compare how different stimuli are spatially distributed, often as gradients, to direct cell movement and the mechanisms by which they steer cells. A comparison of the downstream effectors of directional cues suggests that different external signals regulate a common set of components: small GTPases and the actin cytoskeleton, which implies that the mechanisms downstream of different signals are likely to be closely related and underlies the idea that cell migration operates by a common set of physical principles, irrespective of the input.

Seeing around corners: Cells solve mazes and respond at a distance using attractant breakdown

During development and metastasis, cells migrate large distances through complex environments. Migration is often guided by chemotaxis, but simple chemoattractant gradients between a source and sink cannot direct cells over such ranges. We describe how self-generated gradients, created by cells locally degrading attractant, allow single cells to navigate long, tortuous paths and make accurate choices between live channels and dead ends. This allows cells to solve complex mazes efficiently. Cells' accuracy at finding live channels was determined by attractant diffusivity, cell speed, and path complexity. Manipulating these parameters directed cells in mathematically predictable ways; specific combinations can even actively misdirect them. We propose that the length and complexity of many long-range migratory processes, including inflammation and germ cell migration, means that self-generated gradients are needed for successful navigation.

Multiplexed end-point microfluidic chemotaxis assay using centrifugal alignment

A fundamental challenge to multiplexing microfluidic chemotaxis assays at scale is the requirement for time-lapse imaging to continuously track migrating cells. Drug testing and drug screening applications require the ability to perform hundreds of experiments in parallel, which is not feasible for assays that require continuous imaging. To address this limitation, end-point chemotaxis assays have been developed using fluid flow to align cells in traps or sieves prior to cell migration. However, these methods require precisely controlled fluid flow to transport cells to the correct location without undesirable mechanical stress, which introduce significant set up time and design complexity. Here, we describe a microfluidic device that eliminates the need for precise flow control by using centrifugation to align cells at a common starting point. A chemoattractant gradient is then formed using passive diffusion prior to chemotaxis in an incubated environment. This approach provides a simple and scalable approach to multiplexed chemotaxis assays. Centrifugal alignment is also insensitive to cell geometry, enabling this approach to be compatible with primary cell samples that are often heterogeneous. We demonstrate the capability of this approach by assessing chemotaxis of primary neutrophils in response to an fMLP (N-formyl-met-leu-phe) gradient. Our results show that cell alignment by centrifugation offers a potential avenue to develop scalable end-point multiplexed microfluidic chemotaxis assays.

Advanced Microfluidic Models of Cancer and Immune Cell Extravasation: A Systematic Review of the Literature

Extravasation is a multi-step process implicated in many physiological and pathological events. This process is essential to get leukocytes to the site of injury or infection but is also one of the main steps in the metastatic cascade in which cancer cells leave the primary tumor and migrate to target sites through the vascular route. In this perspective, extravasation is a double-edged sword. This systematic review analyzes microfluidic 3D models that have been designed to investigate the extravasation of cancer and immune cells. The purpose of this systematic review is to provide an exhaustive summary of the advanced microfluidic 3D models that have been designed to study the extravasation of cancer and immune cells, offering a perspective on the current state-of-the-art. To this end, we set the literature search cross-examining PUBMED and EMBASE databases up to January 2020 and further included non-indexed references reported in relevant reviews. The inclusion criteria were defined in agreement between all the investigators, aimed at identifying studies which investigate the extravasation process of cancer cells and/or leukocytes in microfluidic platforms. Twenty seven studies among 174 examined each step of the extravasation process exploiting 3D microfluidic devices and hence were included in our review. The analysis of the results obtained with the use of microfluidic models allowed highlighting shared features and differences in the extravasation of immune and cancer cells, in view of the setup of a common framework, that could be beneficial for the development of therapeutic approaches fostering or hindering the extravasation process.

Label-free ferrohydrodynamic separation of exosome-like nanoparticles

Isolation of exosomes from biological samples provides a minimally-invasive alternative for basic understanding, diagnosis, and prognosis of metastatic cancers. The biology and clinical values of exosomes are under intensive investigation, yet most studies are limited by technical challenges in recovering these exosomes with heterogeneous sizes and cargos from biological samples. We report a novel method based on "particle ferrohydrodynamics" and its associated microfluidic device, termed as the FerroChip, which can separate exosome-like nanoparticles from microliters of cell culture media and human serum in a label-free, continuous-flow and size-dependent manner, and achieves a high recovery rate (94.3%) and a high purity (87.9%). Separated exosome-like nanoparticles had diameters, morphology, and protein expressions that were consistent with other reports. This method, upon further molecular characterization, could potentially facilitate basic understanding of exosomes and its clinical application in blood liquid biopsy.

Durotaxis Index of 3T3 Fibroblast Cells Scales with Stiff-to-Soft Membrane Tension Polarity

Cell durotaxis is an essential process in tissue development. Although the role of cytoskeleton in cell durotaxis has been widely studied, whether cell volume and membrane tension are implicated in cell durotaxis remains unclear. By quantifying the volume distribution during cell durotaxis, we show that the volume of 3T3 fibroblast cells decreases by almost 40% as cells migrate toward stiffer regions of gradient gels. Inhibiting ion transporters that can reduce the amplitude of cell volume decrease significantly suppresses cell durotaxis. However, from the correlation analysis, we find that durotaxis index does not correlate with the cell volume decrease. It scales with the membrane tension difference in the direction of stiffness gradient. Because of the tight coupling between cell volume and membrane tension, inhibition of Na⁺/K⁺ ATPase and Na⁺/H⁺ exchanger results in smaller volume decrease and membrane tension difference. Collectively, our findings indicate that the polarization of membrane tension is a central regulator of cell durotaxis, and Na⁺/K⁺ ATPase and Na⁺/H⁺ exchanger can help to maintain the membrane tension polarity.

The Emerging Role of PPAR Beta/Delta in Tumor Angiogenesis

PPARs are ligand-activated transcriptional factors that belong to the nuclear receptor superfamily. Among them, PPAR alpha and PPAR gamma are prone to exert an antiangiogenic effect, whereas PPAR beta/delta has an opposite effect in physiological and pathological conditions. Angiogenesis has been known as a hallmark of cancer, and our recent works also demonstrate that vascular-specific PPAR beta/delta overexpression promotes tumor angiogenesis and progression in vivo. In this review, we will mainly focus on the role of PPAR beta/delta in tumor angiogenesis linked to the tumor microenvironment to further facilitate tumor progression and metastasis. Moreover, the crosstalk between PPAR beta/delta and its downstream key signal molecules involved in tumor angiogenesis will also be discussed, and the network of interplay between them will further be established in the review.

Small Extracellular Vesicle Regulation of Mitochondrial Dynamics Reprograms a Hypoxic Tumor Microenvironment

The crosstalk between tumor cells and the adjacent normal epithelium contributes to cancer progression, but its regulators have remained elusive. Here, we show that breast cancer cells maintained in hypoxia release small extracellular vesicles (sEVs) that activate mitochondrial dynamics, stimulate mitochondrial movements, and promote organelle accumulation at the cortical cytoskeleton in normal mammary epithelial cells. This results in AKT serine/threonine kinase (Akt) activation, membrane focal adhesion turnover, and increased epithelial cell migration. RNA sequencing profiling identified integrin-linked kinase (ILK) as the most upregulated pathway in sEV-treated epithelial cells, and genetic or pharmacologic targeting of ILK reversed mitochondrial reprogramming and suppressed sEV-induced cell movements. In a three-dimensional (3D) model of mammary gland morphogenesis, sEV treatment induced hallmarks of malignant transformation, with deregulated cell death and/or cell proliferation, loss of apical-basal polarity, and appearance of epithelial-to-mesenchymal transition (EMT) markers. Therefore, sEVs released by hypoxic breast cancer cells reprogram mitochondrial dynamics and induce oncogenic changes in a normal mammary epithelium.

The mitophagy effector FUNDC1 controls mitochondrial reprogramming and cellular plasticity in cancer cells

Mitochondria are signaling hubs in eukaryotic cells. Here, we showed that the mitochondrial FUN14 domain-containing protein-1 (FUNDC1), an effector of Parkin-independent mitophagy, also participates in cellular plasticity by sustaining oxidative bioenergetics, buffering ROS production, and supporting cell proliferation. Targeting this pathway in cancer cells suppressed tumor growth but rendered transformed cells more motile and invasive in a manner dependent on ROS-mediated mitochondrial dynamics and mitochondrial repositioning to the cortical cytoskeleton. Global metabolomics and proteomics profiling identified a FUNDC1 interactome at the mitochondrial inner membrane, comprising the AAA+ protease, LonP1, and subunits of oxidative phosphorylation, complex V (ATP synthase). Independently of its previously identified role in mitophagy, FUNDC1 enabled LonP1 proteostasis, which in turn preserved complex V function and decreased ROS generation. Therefore, mitochondrial reprogramming by a FUNDC1-LonP1 axis controls tumor cell plasticity by switching between proliferative and invasive states in cancer.

Resistance Mechanisms of Anti-PD1/PDL1 Therapy in Solid Tumors

In cancer-immunity cycle, the immune checkpoint PD1 and its ligand PDL1 act as accomplices to help tumors resist to immunity-induced apoptosis and promote tumor progression. Immunotherapy targeting PD1/PDL1 axis can effectively block its pro-tumor activity. Anti-PD1/PDL1 therapy has achieved great success in the past decade. However, only a subset of patients showed clinical responses. Most of the patients can not benefit from anti-PD1/PDL1 therapy. Furthermore, a large group of responders would develop acquired resistance after initial responses. Therefore, understanding the mechanisms of resistance is necessary for improving anti-PD1/PDL1 efficacy. Currently, researchers have identified primary resistance mechanisms which include insufficient tumor immunogenicity, disfunction of MHCs, irreversible T cell exhaustion, primary resistance to IFN-γ signaling, and immunosuppressive microenvironment. Some oncogenic signaling pathways also contribute to the primary resistance. Under the pressure applied by anti-PD1/PDL1 therapy, tumors experience immunoediting and preserve beneficial mutations, upregulate the compensatory inhibitory signaling and induce re-exhaustion of T cells, all of which may attenuate the durability of the therapy. Here we explore the underlying mechanisms in detail, review biomarkers that help identifying responders among patients and discuss the strategies that may relieve the anti-PD1/PDL1 resistance.

NORE1A directs apoptotic switch of TNF signaling through reciprocal modulation of ITCH-mediated destruction of TNFRI and BAX

NORE1A (RASSF5) is a tumor suppressor of the Ras-association domain family (RASSF) that is commonly inactivated in multiple human cancers. However, the molecular mechanism underlying its growth inhibition function remains largely undefined. Here we report that NORE1A antagonizes tumor necrosis factor receptor I (TNFRI) through the assembly of ITCH-mediated destruction complex to suppress TNF-NF-κB signaling and tumorigenesis. Moreover, NORE1A is identified as a transcription target of NF-κB, which directs an apoptotic switch of TNF effect by blocking ITCH interaction with and ubiquitination of BAX. Mechanistically, NORE1A binds directly to TNFRI and ITCH via the C1 and PPXY domains, respectively to facilitate the formation of ITCH-mediated destruction complex followed by ubiquitination-mediated lysosomal degradation of TNFRI. Through this function, NORE1A suppresses TNF-induced NF-κB-mediated transcription of pro-inflammatory and tumor-promoting genes, epithelial-to-mesenchymal transition, invasion and migration of tumor cells, and also debilitates tumor cell activation of macrophage and fibroblast. While NORE1A suppresses TNF receptor-mediated apoptosis, it activates TNF-induced apoptosis through BAX activation by protecting BAX from ITCH binding and ubiquitination. Cytotoxic response to TNF is substantially attenuated in NORE1A-depleted cells and tumors, and NORE1A-induced tumor regression is highly impeded in BAX-depleted tumors. An inverse correlation is shown between NORE1A and TNFRI expression in both cancer cell lines and primary tumors, and NORE1A effect on survival of cancer patients is strongly associated with expression status of ITCH. Collectively, this study uncovers that NORE1A directs a substrate switch of ITCH favoring TNFRI over BAX to terminate TNF signaling and accelerate apoptosis, illuminating the mechanistic consequence of NORE1A inactivation in tumorigenesis.

Actin cytoskeleton in mesenchymal-to-amoeboid transition of cancer cells

During development of metastasis, tumor cells migrate through different tissues and encounter different extracellular matrices. An ability of cells to adapt mechanisms of their migration to these diverse environmental conditions, called migration plasticity, gives tumor cells an advantage over normal cells for long distant dissemination. Different modes of individual cell motility-mesenchymal and amoeboid-are driven by different molecular mechanisms, which largely depend on functions of the actin cytoskeleton that can be modulated in a wide range by cellular signaling mechanisms in response to environmental conditions. Various triggers can switch one motility mode to another, but regulations of these transitions are incompletely understood. However, understanding of the mechanisms driving migration plasticity is instrumental for finding anti-cancer treatment capable to stop cancer metastasis. In this review, we discuss cytoskeletal features, which allow the individually migrating cells to switch between mesenchymal and amoeboid migrating modes, called mesenchymal-to-amoeboid transition (MAT). We briefly describe main characteristics of different cell migration modes, and then discuss the triggering factors that initiate MAT with special attention to cytoskeletal features essential for migration plasticity.

Investigating Optimal Time Step Intervals of Imaging for Data Quality through a Novel Fully-Automated Cell Tracking Approach

Computer-based fully-automated cell tracking is becoming increasingly important in cell biology, since it provides unrivalled capacity and efficiency for the analysis of large datasets. However, automatic cell tracking’s lack of superior pattern recognition and error-handling capability compared to its human manual tracking counterpart inspired decades-long research. Enormous efforts have been made in developing advanced cell tracking packages and software algorithms. Typical research in this field focuses on dealing with existing data and finding a best solution. Here, we investigate a novel approach where the quality of data acquisition could help improve the accuracy of cell tracking algorithms and vice-versa. Generally speaking, when tracking cell movement, the more frequent the images are taken, the more accurate cells are tracked and, yet, issues such as damage to cells due to light intensity, overheating in equipment, as well as the size of the data prevent a constant data streaming. Hence, a trade-off between the frequency at which data images are collected and the accuracy of the cell tracking algorithms needs to be studied. In this paper, we look at the effects of different choices of the time step interval (i.e., the frequency of data acquisition) within the microscope to our existing cell tracking algorithms. We generate several experimental data sets where the true outcomes are known (i.e., the direction of cell migration) by either using an effective chemoattractant or employing no-chemoattractant. We specify a relatively short time step interval (i.e., 30 s) between pictures that are taken at the data generational stage, so that, later on, we may choose some portion of the images to produce datasets with different time step intervals, such as 1 min, 2 min, and so on. We evaluate the accuracy of our cell tracking algorithms to illustrate the effects of these different time step intervals. We establish that there exist certain relationships between the tracking accuracy and the time step interval associated with experimental microscope data acquisition. We perform fully-automatic adaptive cell tracking on multiple datasets, to identify optimal time step intervals for data acquisition, while at the same time demonstrating the performance of the computer cell tracking algorithms.

The role of the tumor microenvironment in tumor cell intravasation and dissemination

Metastasis, a process that requires tumor cell dissemination followed by tumor growth, is the primary cause of death in cancer patients. An essential step of tumor cell dissemination is intravasation, a process by which tumor cells cross the blood vessel endothelium and disseminate to distant sites. Studying this process is of utmost importance given that intravasation in the primary tumor, as well as the secondary and tertiary metastases, is the key step in the systemic spread of tumor cells, and that this process continues even after removal of the primary tumor. High-resolution intravital imaging of the tumor microenvironment of breast carcinoma has revealed that tumor cell intravasation exclusively occurs at doorways, termed "Tumor MicroEnvironment of Metastasis" (TMEM), composed of three different cell types: a Tie2^high/VEGF^high perivascular macrophage, a Mena overexpressing tumor cell, and an endothelial cell, all in direct contact. In this review article, we discuss the interactions between these cell types, the subsequent signaling events which lead to tumor cell intravasation, and the role of invadopodia in supporting tumor cell invasion and dissemination. We end our review by discussing how the knowledge acquired from the use of intravital imaging is now leading to new clinical trials targeting tumor cell dissemination and preventing metastatic progression.

The Biophysics of Cell Migration: Biasing Cell Motion with Feynman Ratchets

The concepts and frameworks of soft matter physics and the laws of thermodynamics can be used to describe relevant developmental, physiologic, and pathologic events in which directed cell migration is involved, such as in cancer. Typically, this directionality has been associated with the presence of soluble long-range gradients of a chemoattractant, synergizing with many other guidance cues to direct the motion of cells. In particular, physical inputs have been shown to strongly influence cell locomotion. However, this type of cue has been less explored despite the importance in biology. In this paper, we describe recent in vitro works at the interface between physics and biology, showing how the motion of cells can be directed by using gradient-free environments with repeated local asymmetries. This rectification of cell migration, from random to directed, is a process reminiscent of the Feynman ratchet; therefore, this framework can be used to explain the mechanism behind directed cell motion.

Cultivated Orostachys japonicus extract inhibits VEGF-induced angiogenesis via regulation of VEGFR2 signaling pathway in vitro and in vivo

ETHNOPHARMACOLOGICAL RELEVANCE

Orostachys japonicus A. Berger (O. japonicus), so-called Wa-song in Korea, a traditional food and medicine that grows on mountain rocks and roof tiles. Wa-song containing various phenolic compounds have been reported as a medicinal plant for prevention of fibrosis, cancer, inflammation, and oxidative damage.

AIM OF THE STUDY

The present study was designed to examine the anti-angiogenic effects of cultivated Orostachys japonicus 70% ethanol extract (CE) in vascular endothelial growth factor (VEGF)-stimulated human umbilical vein endothelial cells (HUVECs).

MATERIALS AND METHODS

CE was prepared with 70% ethanol. HUVECs, rat aortic rings, and matrigel plug in mice were treated with CE (10-20 μg/mL) and VEGF (20-50 ng/mL), and the anti-angiogenic activities of CE were analyzed by SRB, wound healing, trans-well invasion, capillary-like tubule formation, rat aortas, Western blot, and matrigel plug assay. Phenolic compounds in CE were analyzed using a high-performance liquid chromatography (HPLC)-PDA system.

RESULTS

Treatment of CE (10-20 μg/mL) markedly suppressed proliferation of HUVECs in the presence (from 136.5% to 112.2%) or absence of VEGF (from 100.0% to 92.1%). The proliferation inhibitory effect of CE was caused by G0/G1 cell cycle arrest, and the decrease of CDK-2, CDK-4, Cyclin D1 and Cyclin E1. Furthermore, CE treatment showed significant angiogenesis inhibitory effects on motility, invasion and micro-vessel formation of HUVECs, rat aortic rings and subcutaneous matrigels under VEGF-stimulation condition. In HUVECs, CE-induced anti-angiogenic effect was regulated by inhibition of the PI3K/AKT/mTOR, MAPK/p38, MAPK/ERK, FAK-Src, and VEGF-VEGFR2 signaling pathways.

CONCLUSION

This study demonstrated that CE might be used as a potential natural substance, multi-targeted angiogenesis inhibitor, functional food material.

Tumor spheroids under perfusion within a 3D microfluidic platform reveal critical roles of cell-cell adhesion in tumor invasion

Tumor invasion within the interstitial space is critically regulated by the force balance between cell-extracellular matrix (ECM) and cell-cell interactions. Interstitial flows (IFs) are present in both healthy and diseased tissues. However, the roles of IFs in modulating cell force balance and subsequently tumor invasion are understudied. In this article, we develop a microfluidic model in which tumor spheroids are embedded within 3D collagen matrices with well-defined IFs. Using co-cultured tumor spheroids (1:1 mixture of metastatic and non-tumorigenic epithelial cells), we show that IFs downregulate the cell-cell adhesion molecule E-cadherin on non-tumorigenic cells and promote tumor invasion. Our microfluidic model advances current tumor invasion assays towards a more physiologically realistic model using tumor spheroids instead of single cells under perfusion. We identify a novel mechanism by which IFs can promote tumor invasion through an influence on cell-cell adhesion within the tumor and highlight the importance of biophysical parameters in regulating tumor invasion.

From a discrete model of chemotaxis with volume-filling to a generalized Patlak-Keller-Segel model

We present a discrete model of chemotaxis whereby cells responding to a chemoattractant are seen as individual agents whose movement is described through a set of rules that result in a biased random walk. In order to take into account possible alterations in cellular motility observed at high cell densities (i.e. volume-filling), we let the probabilities of cell movement be modulated by a decaying function of the cell density. We formally show that a general form of the celebrated Patlak-Keller-Segel (PKS) model of chemotaxis can be formally derived as the appropriate continuum limit of this discrete model. The family of steady-state solutions of such a generalized PKS model are characterized and the conditions for the emergence of spatial patterns are studied via linear stability analysis. Moreover, we carry out a systematic quantitative comparison between numerical simulations of the discrete model and numerical solutions of the corresponding PKS model, both in one and in two spatial dimensions. The results obtained indicate that there is excellent quantitative agreement between the spatial patterns produced by the two models. Finally, we numerically show that the outcomes of the two models faithfully replicate those of the classical PKS model in a suitable asymptotic regime.

Evaluation of intercellular communication between breast cancer cells and adipose-derived stem cells via passive diffusion in a two-layer microfluidic device

Breast cancer tumorigenesis and response to therapy is regulated by cancer cell interactions with the tumor microenvironment (TME). Breast cancer signaling to the surrounding TME results in a heterogeneous and diverse tumor microenvironment, which includes the production of cancer-associated fibroblasts, macrophages, adipocytes, and stem cells. The secretory profile of these cancer-associated cell types results in elevated chemokines and growth factors that promote cell survival and proliferation within the tumor. Current co-culture approaches mostly rely on transwell chambers to study intercellular signaling between adipose-derived stem cells (ASCs) and cancer cells; however, these methods are limited to endpoint measurements and lack dynamic control. In this study, a 4-channel, "flow-free" microfluidic device was developed to co-culture triple-negative MDA-MB-231 breast cancer cells and ASCs to study intercellular communication between two distinct cell types found in the TME. The device consists of two layers: a top PDMS layer with four imprinted channels coupled with a bottom agarose slab enclosed in a Plexiglas chamber. For dynamic co-culture, the device geometry contained two centered, flow-free channels, which were supplied with media from two outer flow channels via orthogonal diffusion through the agarose. Continuous fresh media was provided to the cell culture channel via passive diffusion without creating any shearing effect on the cells. The device geometry also allowed for the passive diffusion of cytokines and growth factors between the two cell types cultured in parallel channels to initiate cell-to-cell crosstalk. The device was used to show that MDA-MB-231 cells co-cultured with ASCs exhibited enhanced growth, a more aggressive morphology, and polarization toward the ASCs. The MDA-MB-231 cells were found to exhibit a greater degree of resistance to the drug paclitaxel when co-cultured with ASCs when compared to single culture studies. This microfluidic device is an ideal platform to study intercellular communication for many types of cells during co-culture experiments and allows for new investigations into stromal cell-mediated drug resistance in the tumor microenvironment.

Pro-tumorigenic functions of macrophages at the primary, invasive and metastatic tumor site

The tumor microenvironment (TME) not only facilitates cancer progression from the early formation to distant metastasis, but also it differs itself from time to time alongside the tumor evolution. Tumor-associated macrophages (TAMs), whether as pre-existing tissue-resident macrophages or recruited monocytes, are an inseparable part of this microenvironment. As their parents are broadly classified into a dichotomic, simplistic M1 and M2 subtypes, TAMs also exert paradoxical and diverse phenotypes as they are settled in different regions of TME and receive different microenvironmental signals. Briefly, M1 macrophages induce an inflammatory precancerous niche and flame the early oncogenic mutations, whereas their M2 counterparts are reprogrammed to release various growth factors and providing an immunosuppressive state in TME as long as abetting hypoxic cancer cells to set up a new vasculature. Further, they mediate stromal micro-invasion and co-migrate with invasive cancer cells to invade the vascular wall and neural sheath, while another subtype of TAMs prepares suitable niches much earlier than metastatic cells arrive at the target tissues. Accordingly, at the neoplastic transformation, during the benign-to-malignant transition and through the metastatic cascade, macrophages are involved in shaping the primary, micro-invasive and pre-metastatic TMEs. Whether their behavioral plasticity is derived from distinct genotypes or is fueled by microenvironmental cues, it could define these cells as remarkably interesting therapeutic targets.

Small Ones to Fight a Big Problem-Intervention of Cancer Metastasis by Small Molecules

Metastasis represents the most lethal attribute of cancer and critically limits successful therapies in many tumor entities. The clinical need is defined by the fact that all cancer patients, who have or who will develop distant metastasis, will experience shorter survival. Thus, the ultimate goal in cancer therapy is the restriction of solid cancer metastasis by novel molecularly targeted small molecule based therapies. Biomarkers identifying cancer patients at high risk for metastasis and simultaneously acting as key drivers for metastasis are extremely desired. Clinical interventions targeting these key molecules will result in high efficiency in metastasis intervention. In result of this, personalized tailored interventions for restriction and prevention of cancer progression and metastasis will improve patient survival. This review defines crucial biological steps of the metastatic cascade, such as cell dissemination, migration and invasion as well as the action of metastasis suppressors. Targeting these biological steps with tailored therapeutic strategies of intervention or even prevention of metastasis using a wide range of small molecules will be discussed.

Establishment of a scalable microfluidic assay for characterization of population-based neutrophil chemotaxis

BACKGROUND

Regulation of neutrophil chemotaxis and activation plays crucial roles in immunity, and dysregulated neutrophil responses can lead to pathology as seen in neutrophilic asthma. Neutrophil recruitment is key for initiating immune defense and inflammation, and its modulation is a promising therapeutic target. Microfluidic technology is an attractive tool for characterization of neutrophil migration. Compared to transwell assays, microfluidic approaches could offer several advantages, including precis e control of defined chemokine gradients in space and time, automated quantitative analysis of chemotaxis, and high throughput.

METHODS

We established a microfluidic device for fully automated, quantitative assessment of neutrophil chemotaxis. Freshly isolated mouse neutrophils from bone marrow or human neutrophils from peripheral blood were assessed in real time using an epifluorescence microscope for their migration toward the potent chemoattractants C-X-C-motif ligand 2 (CXCL2) and CXCL8, without or with interleukin-4 (IL-4) pre-incubation.

RESULTS

Our microfluidic device allowed the precise and reproducible determination of the optimal CXCL2 and CXCL8 concentrations for mouse and human neutrophil chemotaxis, respectively. Furthermore, our microfluidic assay was able to measure the equilibrium and real-time dynamic effects of specific modulators of neutrophil chemotaxis. We demonstrated this concept by showing that IL-4 receptor signaling in mouse and human neutrophils inhibited their migration toward CXCL2 and CXCL8, respectively, and this inhibition was time-dependent.

CONCLUSION

Collectively, our microfluidic device shows several advantages over traditional transwell migration assays and its design is amenable to future integration into multiplexed high-throughput platforms for screening of molecules that modulate the chemotaxis of different immune cells.

Cell shape, and not 2D migration, predicts extracellular matrix-driven 3D cell invasion in breast cancer

Metastasis, the leading cause of death in cancer patients, requires the invasion of tumor cells through the stroma in response to migratory cues, in part provided by the extracellular matrix (ECM). Recent advances in proteomics have led to the identification of hundreds of ECM proteins, which are more abundant in tumors relative to healthy tissue. Our goal was to develop a pipeline to easily predict which ECM proteins are more likely to have an effect on cancer invasion and metastasis. We evaluated the effect of four ECM proteins upregulated in breast tumor tissue in multiple human breast cancer cell lines in three assays. There was no linear relationship between cell adhesion to ECM proteins and ECM-driven 2D cell migration speed, persistence, or 3D invasion. We then used classifiers and partial-least squares regression analysis to identify which metrics best predicted ECM-driven 2D migration and 3D invasion responses. We find that ECM-driven 2D cell migration speed or persistence did not predict 3D invasion in response to the same cue. However, cell adhesion, and in particular cell elongation and shape irregularity, accurately predicted the magnitude of ECM-driven 2D migration and 3D invasion. Our models successfully predicted the effect of novel ECM proteins in a cell-line specific manner. Overall, our studies identify the cell morphological features that determine 3D invasion responses to individual ECM proteins. This platform will help provide insight into the functional role of ECM proteins abundant in tumor tissue and help prioritize strategies for targeting tumor-ECM interactions to treat metastasis.