Dichotomy of astrocytoma migration and proliferation

Enhanced epithelial-mesenchymal transition signatures are linked with adverse tumor microenvironment, angiogenesis and worse survival in gastric cancer

Epithelial-mesenchymal transition (EMT) is a crucial mechanism that facilitates cancer cell metastasis. Despite its importance, the clinical significance of EMT in gastric cancer (GC) patients has yet to be clearly demonstrated. For gauging the extent of EMT in GC, we employed gene set variation analysis to score 807 patient samples from two large cohorts: TCGA and GSE84437. In both cohorts, EMT high GC showed a significant association with worse overall survival (hazard ratio (HR) = 1.74, p = 0.011 and HR = 2.01, p < 0.001, respectively). This association was stronger when considering the EMT signature score compared to the individual expressions of EMT-related genes (CDH1, CDH2, VIM, and FN1). While the EMT signature level did not differ among various cancers, high EMT signature specifically correlated with survival in GC alone. Mucinous and diffuse histological types exhibited higher EMT levels compared to others (p < 0.001), and the EMT signature level was correlated with tumor depth and AJCC stage (all p < 0.001). Interestingly, the EMT score was an independent factor for overall and disease-specific survival (multivariate; p = 0.006 and 0.032, respectively). EMT high GC displayed a lower fraction of Th1 cells and a higher fraction of dendritic cells, M1 macrophages and several stromal cells. EMT high GC exhibited an inverse correlation with cell proliferation-related gene sets. While they significantly enriched multiple pro-cancerous gene sets, such as TGF-β signaling, hypoxia, and angiogenesis. The presence of EMT signature in a bulk tumor was linked to TGF-β signaling, hypoxia, and angiogenesis, and was also associated with poorer survival outcomes in GC patients.

A simple agent-based hybrid model to simulate the biophysics of glioblastoma multiforme cells and the concomitant evolution of the oxygen field

BACKGROUND AND OBJECTIVES

Glioblastoma multiforme (GBM) is one of the most aggressive cancers of the central nervous system. It is characterized by a high mitotic activity and an infiltrative ability of the glioma cells, neovascularization and necrosis. GBM evolution entails the continuous interplay between heterogeneous cell populations, chemotaxis, and physical cues through different scales. In this work, an agent-based hybrid model is proposed to simulate the coupling of the multiscale biological events involved in the GBM invasion, specifically the individual and collective migration of GBM cells and the concurrent evolution of the oxygen field and phenotypic plasticity. An asset of the formulation is that it is conceptually and computationally simple but allows to reproduce the complexity and the progression of the GBM micro-environment at cell and tissue scales simultaneously.

METHODS

The migration is reproduced as the result of the interaction between every single cell and its micro-environment. The behavior of each individual cell is formulated through genotypic variables whereas the cell micro-environment is modeled in terms of the oxygen concentration and the cell density surrounding each cell. The collective behavior is formulated at a cellular scale through a flocking model. The phenotypic plasticity of the cells is induced by the micro-environment conditions, considering five phenotypes.

RESULTS

The model has been contrasted by benchmark problems and experimental tests showing the ability to reproduce different scenarios of glioma cell migration. In all cases, the individual and collective cell migration and the coupled evolution of both the oxygen field and phenotypic plasticity have been properly simulated. This simple formulation allows to mimic the formation of relevant hallmarks of glioblastoma multiforme, such as the necrotic cores, and to reproduce experimental evidences related to the mitotic activity in pseudopalisades.

CONCLUSIONS

In the collective migration, the survival of the clusters prevails at the expense of cell mitosis, regardless of the size of the groups, which delays the formation of necrotic foci and reduces the rate of oxygen consumption.

Selected aspects of avascular tumor growth reproduced by a hybrid model of cell dynamics and chemical kinetics

We here propose a hybrid computational framework to reproduce and analyze aspects of the avascular progression of a generic solid tumor. Our method first employs an individual-based approach to represent the population of tumor cells, which are distinguished in viable and necrotic agents. The active part of the disease is in turn differentiated according to a set of metabolic states. We then describe the spatio-temporal evolution of the concentration of oxygen and of tumor-secreted proteolytic enzymes using partial differential equations (PDEs). A differential equation finally governs the local degradation of the extracellular matrix (ECM) by the malignant mass. Numerical realizations of the model are run to reproduce tumor growth and invasion in a number scenarios that differ for cell properties (adhesiveness, duplication potential, proteolytic activity) and/or environmental conditions (level of tissue oxygenation and matrix density pattern). In particular, our simulations suggest that tumor aggressiveness, in terms of invasive depth and extension of necrotic tissue, can be reduced by (i) stable cell-cell contact interactions, (ii) poor tendency of malignant agents to chemotactically move upon oxygen gradients, and (iii) presence of an overdense matrix, if coupled by a disrupted proteolytic activity of the disease.

UDP-6-glucose dehydrogenase in hormonally responsive breast cancers

Survival for metastatic breast cancer is low and thus, continued efforts to treat and prevent metastatic progression are critical. Estrogen is shown to promote aggressive phenotypes in multiple cancer models irrespective of estrogen receptor (ER) status. Similarly, UDP-Glucose 6-dehydrogenase (UGDH) a ubiquitously expressed enzyme involved in extracellular matrix precursors, as well as hormone processing increases migratory and invasive properties in cancer models. While the role of UGDH in cellular migration is defined, how it intersects with and impacts hormone signaling pathways associated with tumor progression in metastatic breast cancer has not been explored. Here we demonstrate that UGDH knockdown blunts estrogen-induced tumorigenic phenotypes (migration and colony formation) in ER+ and ER- breast cancer in vitro. Knockdown of UGDH also inhibits extravasation of ER- breast cancer ex vivo, primary tumor growth and animal survival in vivo in both ER+ and ER- breast cancer. We also use single cell RNA-sequencing to demonstrate that our findings translate to a human breast cancer clinical specimen. Our findings support the role of estrogen and UGDH in breast cancer progression provide a foundation for future studies to evaluate the role of UGDH in therapeutic resistance to improve outcomes and survival for breast cancer patients.

Microvascular smooth muscle cells exhibit divergent phenotypic switching responses to platelet-derived growth factor and insulin-like growth factor 1

OBJECTIVE

Vascular smooth muscle cell (VSMC) phenotypic switching is critical for normal vessel formation, vascular stability, and healthy brain aging. Phenotypic switching is regulated by mediators including platelet derived growth factor (PDGF)-BB, insulin-like growth factor (IGF-1), as well as transforming growth factor-β (TGF-β) and endothelin-1 (ET-1), but much about the role of these factors in microvascular VSMCs remains unclear.

METHODS

We used primary rat microvascular VSMCs to explore PDGF-BB- and IGF-1-induced phenotypic switching.

RESULTS

PDGF-BB induced an early proliferative response, followed by formation of polarized leader cells and rapid, directionally coordinated migration. In contrast, IGF-1 induced cell hypertrophy, and only a small degree of migration by unpolarized cells. TGF-β and ET-1 selectively inhibit PDGF-BB-induced VSMC migration primarily by repressing migratory polarization and formation of leader cells. Contractile genes were downregulated by both growth factors, while other genes were differentially regulated by PDGF-BB and IGF-1.

CONCLUSIONS

These studies indicate that PDGF-BB and IGF-1 stimulate different types of microvascular VSMC phenotypic switching characterized by different modes of cell migration. Our studies are consistent with a chronic vasoprotective role for IGF-1 in VSMCs in the microvasculature while PDGF is more involved in VSMC proliferation and migration in response to acute activities such as neovascularization. Better understanding of the nuances of the phenotypic switching induced by these growth factors is important for our understanding of a variety of microvascular diseases.

EBP50 Depletion and Nuclear β-Catenin Accumulation Engender Aggressive Behavior of Colorectal Carcinoma through Induction of Tumor Budding

Ezin-radixin-moesin-binding phosphoprotein 50 (EBP50) is a scaffold protein that interacts with several partner molecules including β-catenin. Here, we examined the crosstalk between EBP50 and nuclear catenin during colorectal carcinoma (CRC) progression. In clinical samples, there were no correlations between the subcellular location of EBP50 and any clinicopathological factors. However, EBP50 expression was significantly lower specifically in the outer areas of tumor lesions, in regions where tumor budding (BD) was observed. Low EBP50 expression was also significantly associated with several unfavorable prognostic factors, suggesting that EBP50 depletion rather than its overexpression or subcellular distribution plays an important role in CRC progression. In CRC cell lines, knockout of EBP50 induced epithelial-mesenchymal transition (EMT)-like features, decreased proliferation, accelerated migration capability, and stabilized nuclear β-catenin due to disruption of the interaction between EBP50 and β-catenin at the plasma membrane. In addition, Slug expression was significantly higher in outer lesions, particularly in BD areas, and was positively correlated with nuclear β-catenin status, consistent with β-catenin-driven transactivation of the Slug promoter. Together, our data suggest that EBP50 depletion releases β-catenin from the plasma membrane in outer tumor lesions, allowing β-catenin to accumulate and translocate to the nucleus, where it transactivates the Slug gene to promote EMT. This in turn triggers tumor budding and contributes to the progression of CRC to a more aggressive phase.

MRTF promotes breast cancer cell motility through SRF-dependent upregulation of DIAPH3 expression

Dysregulated actin cytoskeleton gives rise to aberrant cell motility and metastatic spread of tumor cells. The MRTF-SRF transcriptional complex plays a key role in regulating the expressions of actin cytoskeleton-modulatory genes. In this study, we demonstrate that MRTF's interaction with SRF is critical for migration and invasion of breast cancer cells. Disruption of the MRTF-SRF interaction suppresses membrane dynamics affecting the frequency and the effectiveness of membrane protrusion during cell motility. Consistent with these phenotypic changes, we further show that MRTF promotes actin polymerization at the leading edge, a key aspect of membrane protrusion, and migration of breast cancer cells through upregulating the expression of formin-family actin nucleating/elongating protein encoding gene DIAPH3 in an SRF-dependent manner. In support of these findings, multiplexed quantitative immunohistochemistry and transcriptome analyses of clinical specimens of breast cancer further demonstrate a positive correlation between nuclear localization of MRTF with malignant traits of cancer cells as well as enrichment of MRTF/SRF gene signature in distant metastases relative to primary tumors. In conclusion, this study for the first time links the MRTF/SRF signaling axis to cell migration through the regulation of a specific actin-binding protein, and provides evidence for an association between MRTF/SRF activity and malignancy in human breast cancer.

Individual glioblastoma cells harbor both proliferative and invasive capabilities during tumor progression

BACKGROUND

Glioblastomas are characterized by aggressive and infiltrative growth, and by striking heterogeneity. The aim of this study was to investigate whether tumor cell proliferation and invasion are interrelated, or rather distinct features of different cell populations.

METHODS

Tumor cell invasion and proliferation were longitudinally determined in real-time using 3D in vivo 2-photon laser scanning microscopy over weeks. Glioblastoma cells expressed fluorescent markers that permitted the identification of their mitotic history or their cycling versus non-cycling cell state.

RESULTS

Live reporter systems were established that allowed us to dynamically determine the invasive behavior, and previous or actual proliferation of distinct glioblastoma cells, in different tumor regions and disease stages over time. Particularly invasive tumor cells that migrated far away from the main tumor mass, when followed over weeks, had a history of marked proliferation and maintained their proliferative capacity during brain colonization. Infiltrating cells showed fewer connections to the multicellular tumor cell network, a typical feature of gliomas. Once tumor cells colonized a new brain region, their phenotype progressively transitioned into tumor microtube-rich, interconnected, slower-cycling glioblastoma cells. Analysis of resected human glioblastomas confirmed a higher proliferative potential of tumor cells from the invasion zone.

CONCLUSIONS

The detection of glioblastoma cells that harbor both particularly high proliferative and invasive capabilities during brain tumor progression provides valuable insights into the interrelatedness of proliferation and migration-2 central traits of malignancy in glioma. This contributes to our understanding of how the brain is efficiently colonized in this disease.

Differences in cell shape, motility, and growth reflect chromosomal number variations that can be visualized with live-cell ChReporters

Chromosome numbers often change dynamically in tumors and cultured cells, which complicates therapy as well as understanding genotype-mechanotype relationships. Here we use a live-cell "ChReporter" method to identify cells with a single chromosomal loss in efforts to better understand differences in cell shape, motility, and growth. We focus on a standard cancer line and first show clonal populations that retain the ChReporter exhibit large differences in cell and nuclear morphology as well as motility. Phenotype metrics follow simple rules, including migratory persistence scaling with speed, and cytoskeletal differences are evident from drug responses, imaging, and single-cell RNA sequencing. However, mechanotype-genotype relationships between fluorescent ChReporter-positive clones proved complex and motivated comparisons of clones that differ only in loss or retention of a Chromosome-5 ChReporter. When lost, fluorescence-null cells show low expression of Chromosome-5 genes, including a key tumor suppressor APC that regulates microtubules and proliferation. Colonies are compact, nuclei are rounded, and cells proliferate more, with drug results implicating APC, and patient survival data indicating an association in multiple tumor-types. Visual identification of genotype with ChReporters can thus help clarify mechanotype and mechano-evolution.

Modelling microtube driven invasion of glioma

Malignant gliomas are notoriously invasive, a major impediment against their successful treatment. This invasive growth has motivated the use of predictive partial differential equation models, formulated at varying levels of detail, and including (i) "proliferation-infiltration" models, (ii) "go-or-grow" models, and (iii) anisotropic diffusion models. Often, these models use macroscopic observations of a diffuse tumour interface to motivate a phenomenological description of invasion, rather than performing a detailed and mechanistic modelling of glioma cell invasion processes. Here we close this gap. Based on experiments that support an important role played by long cellular protrusions, termed tumour microtubes, we formulate a new model for microtube-driven glioma invasion. In particular, we model a population of tumour cells that extend tissue-infiltrating microtubes. Mitosis leads to new nuclei that migrate along the microtubes and settle elsewhere. A combination of steady state analysis and numerical simulation is employed to show that the model can predict an expanding tumour, with travelling wave solutions led by microtube dynamics. A sequence of scaling arguments allows us reduce the detailed model into simpler formulations, including models falling into each of the general classes (i), (ii), and (iii) above. This analysis allows us to clearly identify the assumptions under which these various models can be a posteriori justified in the context of microtube-driven glioma invasion. Numerical simulations are used to compare the various model classes and we discuss their advantages and disadvantages.

Heat-shock protein 90α protects NME1 against degradation and suppresses metastasis of breast cancer

BACKGROUND

NME1 has been exploited as a potential translational target for decades. Substantial efforts have been made to upregulate the expression of NME1 and restore its anti-metastasis function in metastatic cancer.

METHODS

Cycloheximide (CHX) chase assay was used to measure the steady-state protein stability of NME1 and HSP90α. The NME1-associating proteins were identified by immunoprecipitation combined with mass spectrometric analysis. Gene knockdown and overexpression were employed to examine the impact of HSP90AA1 on intracellular NME1 degradation. The motility and invasiveness of breast cancer cells were examined in vitro using wound healing and transwell invasion assays. The orthotopic spontaneous metastasis and intra-venous experimental metastasis assays were used to test the formation of metastasis in vivo, respectively.

RESULTS

HSP90α interacts with NME1 and increases NME1 lifetime by impeding its ubiquitin-proteasome-mediated degradation. HSP90α overexpression significantly inhibits the metastatic potential of breast cancer cells in vitro and in vivo. A novel cell-permeable peptide, OPT22 successfully mimics the HSP90α function and prolongs the life span of endogenous NME1, resulting in reduced metastasis of breast cancer.

CONCLUSION

These results not only reveal a new mechanism of NME1 degradation but also pave the way for the development of new and effective approaches to metastatic cancer therapy.

A Narrative Review on CD44's Role in Glioblastoma Invasion, Proliferation, and Tumor Recurrence

High invasiveness is a characteristic of glioblastoma (GBM), making radical resection almost impossible, and thus, resulting in a tumor with inevitable recurrence. GBM recurrence may be caused by glioma stem-like cells (GSCs) that survive many kinds of therapy. GSCs with high expression levels of CD44 are highly invasive and resistant to radio-chemotherapy. CD44 is a multifunctional molecule that promotes the invasion and proliferation of tumor cells via various signaling pathways. Among these, paired pathways reciprocally activate invasion and proliferation under different hypoxic conditions. Severe hypoxia (0.5-2.5% O2) upregulates hypoxia-inducible factor (HIF)-1α, which then activates target genes, including CD44, TGF-β, and cMET, all of which are related to tumor migration and invasion. In contrast, moderate hypoxia (2.5-5% O2) upregulates HIF-2α, which activates target genes, such as vascular endothelial growth factor (VEGF)/VEGFR2, cMYC, and cyclin D1. All these genes are related to tumor proliferation. Oxygen environments around GBM can change before and after tumor resection. Before resection, the oxygen concentration at the tumor periphery is severely hypoxic. In the reparative stage after resection, the resection cavity shows moderate hypoxia. These observations suggest that upregulated CD44 under severe hypoxia may promote the migration and invasion of tumor cells. Conversely, when tumor resection leads to moderate hypoxia, upregulated HIF-2α activates HIF-2α target genes. The phenotypic transition regulated by CD44, leading to a dichotomy between invasion and proliferation according to hypoxic conditions, may play a crucial role in GBM recurrence.

Understanding and leveraging phenotypic plasticity during metastasis formation

Cancer metastasis is the process of detrimental systemic spread and the primary cause of cancer-related fatalities. Successful metastasis formation requires tumor cells to be proliferative and invasive; however, cells cannot be effective at both tasks simultaneously. Tumor cells compensate for this trade-off by changing their phenotype during metastasis formation through phenotypic plasticity. Given the changing selection pressures and competitive interactions that tumor cells face, it is poorly understood how plasticity shapes the process of metastasis formation. Here, we develop an ecology-inspired mathematical model with phenotypic plasticity and resource competition between phenotypes to address this knowledge gap. We find that phenotypically plastic tumor cell populations attain a stable phenotype equilibrium that maintains tumor cell heterogeneity. Considering treatment types inspired by chemo- and immunotherapy, we highlight that plasticity can protect tumors against interventions. Turning this strength into a weakness, we corroborate current clinical practices to use plasticity as a target for adjuvant therapy. We present a parsimonious view of tumor plasticity-driven metastasis that is quantitative and experimentally testable, and thus potentially improving the mechanistic understanding of metastasis at the cell population level, and its treatment consequences.

Interaction between membranous EBP50 and myosin 9 as a favorable prognostic factor in ovarian clear cell carcinoma

Ezrin-radixin-moesin-binding phosphoprotein 50 (EBP50) is a scaffold protein that is required for epithelial polarity. Knockout (KO) of membranous EBP50 (Me-EBP50) in ovarian clear cell carcinoma (OCCC) cells induced an epithelial-mesenchymal transition (EMT)-like phenotype, along with decreased proliferation, accelerated migration capability, and induction of cancer stem cell (CSC)-like properties. Shotgun proteomics analysis of proteins that co-immunoprecipitated with EBP50 revealed that Me-EBP50 strongly interacts with myosin 9 (MYH9). Specific inhibition of MYH9 with blebbistatin phenocopied Me-EBP50 KO, and blebbistatin treatment potentiated the effects of Me-EBP50 KO. In OCCC cells from clinical samples, Me-EBP50 and MYH9 were co-localized at the apical plasma membrane. Patients with a combination of Me-EBP50-high and MYH9-high scores had the best prognosis for overall and progression-free survival. Our data suggest that Me-EBP50 has tumor-suppressive effects through the establishment and maintenance of epithelial polarization. By contrast, loss of Me-EBP50 expression induces EMT-like phenotypes, probably due to MYH9 dysfunction; this results in increased cell mobility and enhanced CSC-like properties, which in turn promote OCCC progression.

Loss of HES1 expression is associated with extracellular matrix remodeling and tumor immune suppression in KRAS mutant colon adenocarcinomas

The loss of HES1, a canonical Notch signaling target, may cooperate with KRAS mutations to remodel the extracellular matrix and to suppress the anti-tumor immune response. While HES1 expression is normal in benign hyperplastic polyps and normal colon tissue, HES1 expression is often lost in sessile serrated adenomas/polyps (SSAs/SSPs) and colorectal cancers (CRCs) such as those right-sided CRCs that commonly harbor BRAF or KRAS mutations. To develop a deeper understanding of interaction between KRAS and HES1 in colorectal carcinogenesis, we selected microsatellite stable (MSS) and KRAS mutant or KRAS wild type CRCs that show aberrant expression of HES1 by immunohistochemistry. By comparing the transcriptional landscapes of microsatellite stable (MSS) CRCs with or without nuclear HES1 expression, we investigated differentially expressed genes and activated pathways. We identified pathways and markers in the extracellular matrix and immune microenvironment that are associated with mutations in KRAS. We found that loss of HES1 expression positively correlated with matrix remodeling and epithelial-mesenchymal transition but negatively correlated with tumor cell proliferation. Furthermore, loss of HES1 expression in KRAS mutant CRCs correlates with a higher M2 macrophage polarization and activation of IL6 and IL10 immunosuppressive signature. Identifying these HES1-related markers may be useful for prognosis stratification and developing treatment for KRAS-mutant CRCs.

Tissue-Engineered Disease Modeling of Lymphangioleiomyomatosis Exposes a Therapeutic Vulnerability to HDAC Inhibition

Lymphangioleiomyomatosis (LAM) is a rare disease involving cystic lung destruction by invasive LAM cells. These cells harbor loss-of-function mutations in TSC2, conferring hyperactive mTORC1 signaling. Here, tissue engineering tools are employed to model LAM and identify new therapeutic candidates. Biomimetic hydrogel culture of LAM cells is found to recapitulate the molecular and phenotypic characteristics of human disease more faithfully than culture on plastic. A 3D drug screen is conducted, identifying histone deacetylase (HDAC) inhibitors as anti-invasive agents that are also selectively cytotoxic toward TSC2-/- cells. The anti-invasive effects of HDAC inhibitors are independent of genotype, while selective cell death is mTORC1-dependent and mediated by apoptosis. Genotype-selective cytotoxicity is seen exclusively in hydrogel culture due to potentiated differential mTORC1 signaling, a feature that is abrogated in cell culture on plastic. Importantly, HDAC inhibitors block invasion and selectively eradicate LAM cells in vivo in zebrafish xenografts. These findings demonstrate that tissue-engineered disease modeling exposes a physiologically relevant therapeutic vulnerability that would be otherwise missed by conventional culture on plastic. This work substantiates HDAC inhibitors as possible therapeutic candidates for the treatment of patients with LAM and requires further study.

A Syx-RhoA-Dia1 signaling axis regulates cell cycle progression, DNA damage, and therapy resistance in glioblastoma

Glioblastomas (GBM) are aggressive tumors that lack effective treatments. Here, we show that the Rho family guanine nucleotide exchange factor Syx promotes GBM cell growth both in vitro and in orthotopic xenografts derived from patients with GBM. Growth defects upon Syx depletion are attributed to prolonged mitosis, increased DNA damage, G2/M cell cycle arrest, and cell apoptosis, mediated by altered mRNA and protein expression of various cell cycle regulators. These effects are phenocopied by depletion of the Rho downstream effector Dia1 and are due, at least in part, to increased phosphorylation, cytoplasmic retention, and reduced activity of the YAP/TAZ transcriptional coactivators. Furthermore, targeting Syx signaling cooperates with radiation treatment and temozolomide (TMZ) to decrease viability in GBM cells, irrespective of their inherent response to TMZ. The data indicate that a Syx-RhoA-Dia1-YAP/TAZ signaling axis regulates cell cycle progression, DNA damage, and therapy resistance in GBM and argue for its targeting for cancer treatment.

Single-cell phenotypic plasticity modulates social behavior in Dictyostelium discoideum

In Dictyostelium chimeras, "cheaters" are strains that positively bias their contribution to the pool of spores, i.e., the reproductive cells resulting from development. On evolutionary time scales, the selective advantage; thus, gained by cheaters is predicted to undermine collective functions whenever social behaviors are genetically determined. Genotypes; however, are not the sole determinant of spore bias, but the relative role of genetic and plastic differences in evolutionary success is unclear. Here, we study chimeras composed of cells harvested in different phases of population growth. We show that such heterogeneity induces frequency-dependent, plastic variation in spore bias. In genetic chimeras, the magnitude of such variation is not negligible and can even reverse the classification of a strain's social behavior. Our results suggest that differential cell mechanical properties can underpin, through biases emerging during aggregation, a "lottery" in strains' reproductive success that may counter the evolution of cheating.

Exploring the Vital Link Between Glioma, Neuron, and Neural Activity in the Context of Invasion

Because of their ability to infiltrate normal brain tissue, gliomas frequently evade microscopic surgical excision. The histologic infiltrative property of human glioma has been previously characterized as Scherer secondary structures, of which the perivascular satellitosis is a prospective target for anti-angiogenic treatment in high-grade gliomas. However, the mechanisms underlying perineuronal satellitosis remain unclear, and therapy remains lacking. Our knowledge of the mechanism underlying Scherer secondary structures has improved over time. New techniques, such as laser capture microdissection and optogenetic stimulation, have advanced our understanding of glioma invasion mechanisms. Although laser capture microdissection is a useful tool for studying gliomas that infiltrate the normal brain microenvironment, optogenetics and mouse xenograft glioma models have been extensively used in studies demonstrating the unique role of synaptogenesis in glioma proliferation and identification of potential therapeutic targets. Moreover, a rare glioma cell line is established that, when transplanted in the mouse brain, can replicate and recapitulate the human diffuse invasion phenotype. This review discusses the primary molecular causes of glioma, its histopathology-based invasive mechanisms, and the importance of neuronal activity and interactions between glioma cells and neurons in the brain microenvironment. It also explores current methods and models of gliomas.

Molecular mechanisms of microRNAs in glioblastoma pathogenesis

Glioblastoma (GBM) is human's most prevalent and severe brain cancer. Epigenetic regulators, micro(mi)RNAs, significantly impact cellular health and disease because of their wide range of targets and functions. The "epigenetic symphony" in which miRNAs perform is responsible for orchestrating the transcription of genetic information. The discovery of regulatory miRNA activities in GBM biology has shown that various miRNAs play a vital role in disease onset and development. Here, we summarize our current understanding of the current state-of-the-art and latest findings regarding the interactions between miRNAs and molecular mechanisms commonly associated with GBM pathogenesis. Moreover, by literature review and reconstruction of the GBM gene regulatory network, we uncovered the connection between miRNAs and critical signaling pathways such as cell proliferation, invasion, and cell death, which provides promising hints for identifying potential therapeutic targets for the treatment of GBM. In addition, the role of miRNAs in GBM patient survival was investigated. The present review, which contains new analyses of the previous literature, may lead to new avenues to explore in the future for the development of multitargeted miRNA-based therapies for GBM.

Cellular states are coupled to genomic and viral heterogeneity in HPV-related oropharyngeal carcinoma

Head and neck squamous cell carcinoma (HNSCC) includes a subset of cancers driven by human papillomavirus (HPV). Here we use single-cell RNA-seq to profile both HPV-positive and HPV-negative oropharyngeal tumors, uncovering a high level of cellular diversity within and between tumors. First, we detect diverse chromosomal aberrations within individual tumors, suggesting genomic instability and enabling the identification of malignant cells even at pathologically negative margins. Second, we uncover diversity with respect to HNSCC subtypes and other cellular states such as the cell cycle, senescence and epithelial-mesenchymal transitions. Third, we find heterogeneity in viral gene expression within HPV-positive tumors. HPV expression is lost or repressed in a subset of cells, which are associated with a decrease in HPV-associated cell cycle phenotypes, decreased response to treatment, increased invasion and poor prognosis. These findings suggest that HPV expression diversity must be considered during diagnosis and treatment of HPV-positive tumors, with important prognostic ramifications.

Traveling wave speed and profile of a "go or grow" glioblastoma multiforme model

Glioblastoma multiforme (GBM) is a fast-growing and deadly brain tumor due to its ability to aggressively invade the nearby brain tissue. A host of mathematical models in the form of reaction-diffusion equations have been formulated and studied in order to assist clinical assessment of GBM growth and its treatment prediction. To better understand the speed of GBM growth and form, we propose a two population reaction-diffusion GBM model based on the 'go or grow' hypothesis. Our model is validated by in vitro data and assumes that tumor cells are more likely to leave and search for better locations when resources are more limited at their current positions. Our findings indicate that the tumor progresses slower than the simpler Fisher model, which is known to overestimate GBM progression. Moreover, we obtain accurate estimations of the traveling wave solution profiles under several plausible GBM cell switching scenarios by applying the approximation method introduced by Canosa.

Low-Density Lipoprotein Pathway Is a Ubiquitous Metabolic Vulnerability in High Grade Glioma Amenable for Nanotherapeutic Delivery

Metabolic reprogramming, through increased uptake of cholesterol in the form of low-density lipoproteins (LDL), is one way by which cancer cells, including high grade gliomas (HGG), maintain their rapid growth. In this study, we determined LDL receptor (LDLR) expression in HGGs using immunohistochemistry on tissue microarrays from intra- and inter tumour regions of 36 adult and 133 paediatric patients to confirm LDLR as a therapeutic target. Additionally, we analysed expression levels in three representative cell line models to confirm their future utility to test LDLR-targeted nanoparticle uptake, retention, and cytotoxicity. Our data show widespread LDLR expression in adult and paediatric cohorts, but with significant intra-tumour variation observed between the core and either rim or invasive regions of adult HGG. Expression was independent of paediatric tumour grade or identified clinicopathological factors. LDLR-expressing tumour cells localized preferentially within perivascular niches, also with significant adult intra-tumour variation. We demonstrated variable levels of LDLR expression in all cell lines, confirming their suitability as models to test LDLR-targeted nanotherapy delivery. Overall, our study reveals the LDLR pathway as a ubiquitous metabolic vulnerability in high grade gliomas across all ages, amenable to future consideration of LDL-mediated nanoparticle/drug delivery to potentially circumvent tumour heterogeneity.

Prognostic significance of p16, p21, and Ki67 expression at the invasive front of colorectal cancers

Cancer cells at the invasive front are believed to be responsible for invasion/metastasis. This has led to examining various morphological features and protein expressions at the invasive front. However, accurate assessment of the pathological section requires long-time training, and inter-observer disagreement is problematic. Immunohistochemistry and digital imaging analysis may mitigate these problems; however, the choice of which proteins to stain and the best analysis method remains controversial. We used the "go-or-grow" hypothesis to select markers with the greatest prognostic relevance. Importantly, nonproliferating cells can migrate. We used Ki67 as a proliferation marker, with p16 and p21 designating nonproliferating cells. We established a semi-automated quantification workflow to study protein expression in serial pathological sections. A total of 51 patients with completely resected colorectal cancer (stages I-IV) were analyzed, and 44 patients were followed up. Patients with cancer cells with p16-high/p21-low or p21-low/Ki67-low at the deepest invasive front demonstrated a significantly worse prognosis than those who did not display these characteristics. These results suggest that the nonproliferating cancer cells at the invasion front possess invasion/metastatic property with heterogeneity of senescence.

A dynamical model of combination therapy applied to glioma

Glioma is a human brain tumor that is very difficult to treat at an advanced stage. Studies of glioma biomarkers have shown that some markers are released into the bloodstream, so data from these markers indicate a decrease in the concentration of blood glucose and serum glucose in patients with glioma; these suggest an association between glucose and glioma. This decrease mechanism in glucose concentration can be described by the coupled ordinary differential equations of the early-stage glioma growth and interactions between glioma cells, immune cells, and glucose concentration. In this paper, we propose developing a new mathematical model to explain how glioma cells evolve and survive combination therapy between chemotherapy and oncolytic virotherapy, as an alternative to glioma treatment. In this study, three therapies were applied for analysis, that is, (1) chemotherapy, (2) virotherapy, and (3) a combination of chemotherapy and virotherapy. Virotherapy uses specialist viruses that only attack tumor cells. Based on the simulation results of the therapy carried out, we conclude that combination therapy can reduce the glioma cells significantly compared to the other two therapies. The simulation results of this combination therapy can be an alternative to glioma therapy.

PTEN overexpression and nuclear β-catenin stabilization promote morular differentiation through induction of epithelial-mesenchymal transition and cancer stem cell-like properties in endometrial carcinoma

BACKGROUND

Although a lack of functional PTEN contributes to tumorigenesis in a wide spectrum of human malignancies, little is known about the functional role of its overexpression in the tumors. The current study focused on PTEN overexpression in endometrial carcinoma (Em Ca).

METHODS

The functional impact of PTEN overexpression was assessed by Em Ca cell lines. Immunohistochemical analyses were also conducted using 38 Em Ca with morular lesions.

RESULTS

Em Ca cell lines stably overexpressing PTEN (H6-PTEN) exhibited epithelial-mesenchymal transition (EMT)-like features, probably through β-catenin/Slug-meditated suppression of E-cadherin. PTEN overexpression also inhibited cell proliferation, accelerated cellular senescence, increased apoptotic features, and enhanced migration capability. Moreover, H6-PTEN cells exhibited cancer stem cell (CSC)-like properties, along with high expression of aldehyde dehydrogenase 1 and CD44s, a large ALDH 1^high population, enriched spheroid formation, and β-catenin-mediated upregulation of cyclin D2, which is required for persistent CSC growth. In clinical samples, immunoreactivities for PTEN, as well as CSC-related molecules, were significantly higher in morular lesions as compared to the surrounding carcinomas. PTEN score was positively correlated with expression of nuclear β-catenin, cytoplasmic CD133, and CD44v6, and negatively with cell proliferation. Finally, estrogen receptor-α (ERα)-dependent expression of Ezrin-radixin-moesin-binding phophoprotein-50 (EBP50), a multifunctional scaffolding protein, acts as a negative regulator of morular formation by Em Ca cells through interacting with PTEN and β-catenin.

CONCLUSION

In the abscess of ERα/EBP50 expression, PTEN overexpression and nuclear β-catenin stabilization promote the establishment and maintenance of morular phenotype associated with EMT/CSC-like features in Em Ca cells. Video Abstract.

Perivascular Stromal Cells Instruct Glioblastoma Invasion, Proliferation, and Therapeutic Response within an Engineered Brain Perivascular Niche Model

Glioblastoma (GBM) tumor cells are found in the perivascular niche microenvironment and are believed to associate closely with the brain microvasculature. However, it is largely unknown how the resident cells of the perivascular niche, such as endothelial cells, pericytes, and astrocytes, influence GBM tumor cell behavior and disease progression. A 3D in vitro model of the brain perivascular niche developed by encapsulating brain-derived endothelial cells, pericytes, and astrocytes in a gelatin hydrogel is described. It is shown that brain perivascular stromal cells, namely pericytes and astrocytes, contribute to vascular architecture and maturation. Cocultures of patient-derived GBM tumor cells with brain microvascular cells are used to identify a role for pericytes and astrocytes in establishing a perivascular niche environment that modulates GBM cell invasion, proliferation, and therapeutic response. Engineered models provide unique insight regarding the spatial patterning of GBM cell phenotypes in response to a multicellular model of the perivascular niche. Critically, it is shown that engineered perivascular models provide an important resource to evaluate mechanisms by which intercellular interactions modulate GBM tumor cell behavior, drug response, and provide a framework to consider patient-specific disease phenotypes.

The Impact of Phenotypic Heterogeneity on Chemotactic Self-Organisation

The capacity to aggregate through chemosensitive movement forms a paradigm of self-organisation, with examples spanning cellular and animal systems. A basic mechanism assumes a phenotypically homogeneous population that secretes its own attractant, with the well known system introduced more than five decades ago by Keller and Segel proving resolutely popular in modelling studies. The typical assumption of population phenotypic homogeneity, however, often lies at odds with the heterogeneity of natural systems, where populations may comprise distinct phenotypes that vary according to their chemotactic ability, attractant secretion, etc. To initiate an understanding into how this diversity can impact on autoaggregation, we propose a simple extension to the classical Keller and Segel model, in which the population is divided into two distinct phenotypes: those performing chemotaxis and those producing attractant. Using a combination of linear stability analysis and numerical simulations, we demonstrate that switching between these phenotypic states alters the capacity of a population to self-aggregate. Further, we show that switching based on the local environment (population density or chemoattractant level) leads to diverse patterning and provides a route through which a population can effectively curb the size and density of an aggregate. We discuss the results in the context of real world examples of chemotactic aggregation, as well as theoretical aspects of the model such as global existence and blow-up of solutions.

Suppressor of fused associates with dissemination patterns in patients with glioma

Gliomas are the most common brain tumors, which present poor prognosis, due, in part, to tumor cell migration and infiltration into distant brain areas. However, the underlying mechanisms causing such effects are unknown. Hedgehog (HH)–Gli axis is one of the signaling pathways involved, with a high number of molecular mediators. In this study, we investigated the association between HH-Gli intermediates and clinical parameters. We found that high levels of SuFu are associated with high dissemination patterns in patients with glioma. Therefore, we analyzed SuFu expression data in three glioma cohorts of surgical samples (N =1,759) and modified its expression in Glioblastoma Cancer Stem Cells (GB CSC) in vitro models. Our data reveal that SuFu overexpression increases cancer stemness properties together with a migratory phenotype. This work identifies SuFu as a new molecular player in glioma cell migration and a promising target to develop blocking agents to decrease GB dissemination.

The Cytoskeleton Effectors Rho-Kinase (ROCK) and Mammalian Diaphanous-Related (mDia) Formin Have Dynamic Roles in Tumor Microtube Formation in Invasive Glioblastoma Cells

Glioblastoma (GBM) is a progressive and lethal brain cancer. Malignant control of actin and microtubule cytoskeletal mechanics facilitates two major GBM therapeutic resistance strategies-diffuse invasion and tumor microtube network formation. Actin and microtubule reorganization is controlled by Rho-GTPases, which exert their effects through downstream effector protein activation, including Rho-associated kinases (ROCK) 1 and 2 and mammalian diaphanous-related (mDia) formins (mDia1, 2, and 3). Precise spatial and temporal balancing of the activity between these effectors dictates cell shape, adhesion turnover, and motility. Using small molecules targeting mDia, we demonstrated that global agonism (IMM02) was superior to antagonism (SMIFH2) as anti-invasion strategies in GBM spheroids. Here, we use IDH-wild-type GBM patient-derived cell models and a novel semi-adherent in vitro system to investigate the relationship between ROCK and mDia in invasion and tumor microtube networks. IMM02-mediated mDia agonism disrupts invasion in GBM patient-derived spheroid models, in part by inducing mDia expression loss and tumor microtube network collapse. Pharmacological disruption of ROCK prevented invasive cell-body movement away from GBM spheres, yet induced ultralong, phenotypically abnormal tumor microtube formation. Simultaneously targeting mDia and ROCK did not enhance the anti-invasive/-tumor microtube effects of IMM02. Our data reveal that targeting mDia is a viable GBM anti-invasion/-tumor microtube networking strategy, while ROCK inhibition is contraindicated.

Functional interaction between S100A1 and MDM2 may modulate p53 signaling in normal and malignant endometrial cells

BACKGROUND

S100A1 expression is deregulated in a variety of human malignancies, but its role in normal and malignant endometrial cells is unclear.

METHODS

We used endometrial carcinoma (Em Ca) cell lines to evaluate the physical and functional interaction of S100A1 with p53 and its negative regulator, mouse double minute 2 (MDM2). We also evaluated the expression of S100A1, p53, and MDM2 in clinical samples consisting of 89 normal endometrial and 189 Em Ca tissues.

RESULTS

S100A1 interacted with MDM2 but not p53 in Em Ca cell lines. Treatment of cells stably overexpressing S100A1 with Nutlin-3A, an inhibitor of the p53/MDM2 interaction, increased expression of p53-target genes including p21^waf1 and BAX. S100A1 overexpression enhanced cellular migration, but also sensitized cells to the antiproliferative and proapoptotic effects of Adriamycin, a genotoxic agent; these phenotypes were abrogated when S100A1 was knocked down using shRNA. In clinical samples from normal endometrium, S100A1 expression was significantly higher in endometrial glandular cells of the middle/late secretory and menstrual stages when compared to cells in the proliferative phases; high S100A1 was also positively correlated with expression of MDM2 and p21^waf1 and apoptotic status, and inversely correlated with Ki-67 scores. However, such correlations were absent in Em Ca tissues.

CONCLUSION

The interaction between S100A1 and MDM2 may modulate proliferation, susceptibility to apoptosis, and migration through alterations in p53 signaling in normal- but not malignant-endometrial cells.

The Roles of EphB2 in Cancer

The erythropoietin-producing hepatocellular carcinoma (Eph) receptors and their Eph receptor-interacting (ephrin) ligands together constitute a vital cell communication system with diverse roles. Experimental evidence revealed Eph receptor bidirectional signaling with both tumor-promoting and tumor-suppressing activities in different cancer types and surrounding environment. Eph receptor B2 (EphB2), an important member of the Eph receptor family, has been proved to be aberrantly expressed in many cancer types, such as colorectal cancer, gastric cancer and hepatocellular carcinoma, resulting in tumor occurrence and progression. However, there are no reviews focusing on the dual roles of EphB2 in cancer. Thus, in this paper we systematically summarize and discuss the roles of EphB2 in cancer. Firstly, we review the main biological features and the related signaling regulatory mechanisms of EphB2, and then we summarize the roles of EphB2 in cancer through current studies. Finally, we put forward our viewpoint on the future prospects of cancer research focusing on EphB2, especially with regard to the effects of EphB2 on tumor immunity.

A phenotype-structured model to reproduce the avascular growth of a tumor and its interaction with the surrounding environment

We here propose a one-dimensional spatially explicit phenotype-structured model to analyze selected aspects of avascular tumor progression. In particular, our approach distinguishes viable and necrotic cell fractions. The metabolically active part of the disease is, in turn, differentiated according to a continuous trait, that identifies cell variants with different degrees of motility and proliferation potential. A parabolic partial differential equation (PDE) then governs the spatio-temporal evolution of the phenotypic distribution of active cells within the host tissue. In this respect, active tumor agents are allowed to duplicate, move upon haptotactic and pressure stimuli, and eventually undergo necrosis. The mutual influence between the emerging malignancy and its environment (in terms of molecular landscape) is implemented by coupling the evolution law of the viable tumor mass with a parabolic PDE for oxygen kinetics and a differential equation that accounts for local consumption of extracellular matrix (ECM) elements. The resulting numerical realizations reproduce tumor growth and invasion in a number scenarios that differ for cell properties (i.e., individual migratory behavior, duplication and mutation potential) and environmental conditions (i.e., level of tissue oxygenation and homogeneity in the initial matrix profile). In particular, our simulations show that, in all cases, more mobile cell variants occupy the front edge of the tumor, whereas more proliferative clones are selected at the more internal regions. A necrotic core constantly occupies the bulk of the mass due to nutrient deprivation. This work may eventually suggest some biomedical strategies to partially reduce tumor aggressiveness, i.e., to enhance necrosis of malignant tissue and to promote the presence of more proliferative cell phenotypes over more invasive ones.

Mitosis, a springboard for epithelial-mesenchymal transition?

Mitosis is a key process in development and remains critical to ensure homeostasis in adult tissues. Besides its primary role in generating two new cells, cell division involves deep structural and molecular changes that might have additional effects on cell and tissue fate and shape. Specific quantitative and qualitative regulation of mitosis has been observed in multiple morphogenetic events in different embryo models. For instance, during mouse embryo gastrulation, the portion of epithelium that undergoes epithelial to mesenchymal transition, where a static epithelial cell become mesenchymal and motile, has a higher mitotic index and a distinct localization of mitotic rounding, compared to the rest of the tissue. Here we explore the potential mechanisms through which mitosis may favor tissue reorganization in various models. Notably, we discuss the mechanical impact of cell rounding on the cell and its environment, and the modification of tissue physical parameters through changes in cell-cell and cell-matrix adhesion.

Multidimensional hydrogel models reveal endothelial network angiocrine signals increase glioblastoma cell number, invasion, and temozolomide resistance

Glioblastoma (GBM) is the most common primary malignant brain tumor. The tissue microenvironment adjacent to vasculature, termed the perivascular niche, has been implicated in promoting biological processes involved in glioblastoma progression such as invasion, proliferation, and therapeutic resistance. However, the exact nature of the cues that support tumor cell aggression in this niche is largely unknown. Soluble angiocrine factors secreted by tumor-associated vasculature have been shown to support such behaviors in other cancer types. Here, we exploit macroscopic and microfluidic gelatin hydrogel platforms to profile angiocrine factors secreted by self-assembled endothelial networks and evaluate their relevance to glioblastoma biology. Aggregate angiocrine factors support increases in U87-MG cell number, migration, and therapeutic resistance to temozolomide. We also identify a novel role for TIMP1 in facilitating glioblastoma tumor cell migration. Overall, this work highlights the use of multidimensional hydrogel models to evaluate the role of angiocrine signals in glioblastoma progression.

Wound Healing Driver Gene and Therapeutic Development: Political and Scientific Hurdles

Significance: Since the last Food and Drug Administration (FDA) approval of a wound healing therapeutic in 1997, no new therapeutic candidate (excluding physical therapies, devices, dressings, and antimicrobial agents) has advanced to clinical applications. During this period, the FDA drug approvals for tumors, which have been referred to as "wounds that do not heal," have reached a total of 284 (by end of 2018). Both political and scientific factors may explain this large discrepancy in drug approvals for the two seemingly related and equally complex pathophysiological conditions. Recent Advances: Using the current research funding ratio of 1:150 for wound healing to cancer and the 5% FDA drug approval rate for oncology, we reach a crude estimate of a 0.03% success rate for wound healing therapeutics. Unless a drastic improvement of the current situation, we express a pessimistic outlook toward new and effective wound healing drugs. Critical Issues: We argue that successful development of wound healing therapeutics will rely on identification of wound healing driver genes (WDGs), and the focus should be on WDGs for the wound closure phase of wound healing. Therefore, WDGs must be both necessary and sufficient for wound closure; the absence of a WDG disrupts wound closure, while its supplementation alone is sufficient to restore full wound closure. Successful translation of a WDG into therapeutics requires availability of well-defined animal models with a high degree of relevance to humans. This review discusses the main hurdles faced by the wound healing research community behind the development of so-called "rescuing drugs" for wound healing. Future Directions: Given the lack of new wound healing drugs for the past 23 years, there is a need for a wide range of fresh, innovative, and thorough debates on wound healing drug development, including an organized movement to raise public support for wound healing research.

Improving personalized tumor growth predictions using a Bayesian combination of mechanistic modeling and machine learning

BACKGROUND

In clinical practice, a plethora of medical examinations are conducted to assess the state of a patient's pathology producing a variety of clinical data. However, investigation of these data faces two major challenges. Firstly, we lack the knowledge of the mechanisms involved in regulating these data variables, and secondly, data collection is sparse in time since it relies on patient's clinical presentation. The former limits the predictive accuracy of clinical outcomes for any mechanistic model. The latter restrains any machine learning algorithm to accurately infer the corresponding disease dynamics.

METHODS

Here, we propose a novel method, based on the Bayesian coupling of mathematical modeling and machine learning, aiming at improving individualized predictions by addressing the aforementioned challenges.

RESULTS

We evaluate the proposed method on a synthetic dataset for brain tumor growth and analyze its performance in predicting two relevant clinical outputs. The method results in improved predictions in almost all simulated patients, especially for those with a late clinical presentation (>95% patients show improvements compared to standard mathematical modeling). In addition, we test the methodology in two additional settings dealing with real patient cohorts. In both cases, namely cancer growth in chronic lymphocytic leukemia and ovarian cancer, predictions show excellent agreement with reported clinical outcomes (around 60% reduction of mean squared error).

CONCLUSIONS

We show that the combination of machine learning and mathematical modeling approaches can lead to accurate predictions of clinical outputs in the context of data sparsity and limited knowledge of disease mechanisms.

Mechanoresponsive metabolism in cancer cell migration and metastasis

Altered tissue mechanics and metabolism are defining characteristics of cancer that impact not only proliferation but also migration. While migrating through a mechanically and spatially heterogeneous microenvironment, changes in metabolism allow cells to dynamically tune energy generation and bioenergetics in response to fluctuating energy needs. Physical cues from the extracellular matrix influence mechanosignaling pathways, cell mechanics, and cytoskeletal architecture to alter presentation and function of metabolic enzymes. In cancer, altered mechanosensing and metabolic reprogramming supports metabolic plasticity and high energy production while cells migrate and metastasize. Here, we discuss the role of mechanoresponsive metabolism in regulating cell migration and supporting metastasis as well as the potential of therapeutically targeting cancer metabolism to block motility and potentially metastasis.

Non-local multiscale approach for the impact of go or grow hypothesis on tumour-viruses interactions

We propose and study computationally a novel non-local multiscale moving boundary mathematical model for tumour and oncolytic virus (OV) interactions when we consider the go or grow hypothesis for cancer dynamics. This spatio-temporal model focuses on two cancer cell phenotypes that can be infected with the OV or remain uninfected, and which can either move in response to the extracellular-matrix (ECM) density or proliferate. The interactions between cancer cells, those among cancer cells and ECM, and those among cells and OV occur at the macroscale. At the micro-scale, we focus on the interactions between cells and matrix degrading enzymes (MDEs) that impact the movement of tumour boundary. With the help of this multiscale model we explore the impact on tumour invasion patterns of two different assumptions that we consider in regard to cell-cell and cell-matrix interactions. In particular we investigate model dynamics when we assume that cancer cell fluxes are the result of local advection in response to the density of extracellular matrix (ECM), or of non-local advection in response to cell-ECM adhesion. We also investigate the role of the transition rates between mainly-moving and mainly-growing cancer cell sub-populations, as well as the role of virus infection rate and virus replication rate on the overall tumour dynamics.

Cancer cell metabolic plasticity in migration and metastasis

Metabolic reprogramming is a hallmark of cancer metastasis in which cancer cells manipulate their metabolic profile to meet the dynamic energetic requirements of the tumor microenvironment. Though cancer cell proliferation and migration through the extracellular matrix are key steps of cancer progression, they are not necessarily fueled by the same metabolites and energy production pathways. The two main metabolic pathways cancer cells use to derive energy from glucose, glycolysis and oxidative phosphorylation, are preferentially and plastically utilized by cancer cells depending on both their intrinsic metabolic properties and their surrounding environment. Mechanical factors in the microenvironment, such as collagen density, pore size, and alignment, and biochemical factors, such as oxygen and glucose availability, have been shown to influence both cell migration and glucose metabolism. As cancer cells have been identified as preferentially utilizing glycolysis or oxidative phosphorylation based on heterogeneous intrinsic or extrinsic factors, the relationship between cancer cell metabolism and metastatic potential is of recent interest. Here, we review current in vitro and in vivo findings in the context of cancer cell metabolism during migration and metastasis and extrapolate potential clinical applications of this work that could aid in diagnosing and tracking cancer progression in vivo by monitoring metabolism. We also review current progress in the development of a variety of metabolically targeted anti-metastatic drugs, both in clinical trials and approved for distribution, and highlight potential routes for incorporating our recent understanding of metabolic plasticity into therapeutic directions. By further understanding cancer cell energy production pathways and metabolic plasticity, more effective and successful clinical imaging and therapeutics can be developed to diagnose, target, and inhibit metastasis.

Hypoxia-induced phenotypic transition from highly invasive to less invasive tumors in glioma stem-like cells: Significance of CD44 and osteopontin as therapeutic targets in glioblastoma

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CD44, upregulated by HIF-1α under 1%O₂, induces highly invasive phenotype GSCs.

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HIF-2α-activated OPN under 5%O₂ promotes less-invasive/proliferative type GSCs.

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CD44 and OPN knockdowns inhibit in vitro/vivo GSCs invasion and proliferation.

The poor prognosis of glioblastoma multiforme (GBM) is primarily due to highly invasive glioma stem-like cells (GSCs) in tumors. Upon GBM recurrence, GSCs with highly invasive and highly migratory activities must assume a less-motile state and proliferate to regenerate tumor mass. Elucidating the molecular mechanism underlying this transition from a highly invasive phenotype to a less-invasive, proliferative tumor could facilitate the identification of effective molecular targets for treating GBM. Here, we demonstrate that severe hypoxia (1% O₂) upregulates CD44 expression via activation of hypoxia-inducible factor (HIF-1α), inducing GSCs to assume a highly invasive tumor. In contrast, moderate hypoxia (5% O₂) upregulates osteopontin expression via activation of HIF-2α. The upregulated osteopontin inhibits CD44-promoted GSC migration and invasion and stimulates GSC proliferation, inducing GSCs to assume a less-invasive, highly proliferative tumor. These data indicate that the GSC phenotype is determined by interaction between CD44 and osteopontin. The expression of both CD44 and osteopontin is regulated by differential hypoxia levels. We found that CD44 knockdown significantly inhibited GSC migration and invasion both in vitro and in vivo. Mouse brain tumors generated from CD44-knockdown GSCs exhibited diminished invasiveness, and the mice survived significantly longer than control mice. In contrast, siRNA-mediated silencing of the osteopontin gene decreased GSC proliferation. These results suggest that interaction between CD44 and osteopontin plays a key role in tumor progression in GBM; inhibition of both CD44 and osteopontin may represent an effective therapeutic approach for suppressing tumor progression, thus resulting in a better prognosis for patients with GBM.

Metabolic plasticity enables lifestyle transitions of Porphyromonas gingivalis

Our understanding of how the oral anaerobe Porphyromonas gingivalis can persist below the gum line, induce ecological changes, and promote polymicrobial infections remains limited. P. gingivalis has long been described as a highly proteolytic and asaccharolytic pathogen that utilizes protein substrates as the main source for energy production and proliferation. Here, we report that P. gingivalis displays a metabolic plasticity that enables the exploitation of non-proteinaceous substrates, specifically the monocarboxylates pyruvate and lactate, as well as human serum components, for colonization and biofilm formation. We show that anabolism of carbohydrates from pyruvate is powered by catabolism of amino acids. Concomitantly, the expression of fimbrial adhesion is upregulated, leading to the enhancement of biofilm formation, stimulation of multispecies biofilm development, and increase of colonization and invasion of the primary gingival epithelial cells by P. gingivalis. These studies provide the first glimpse into the metabolic plasticity of P. gingivalis and its adaptation to the nutritional condition of the host niche. Our findings support the model that in response to specific nutritional parameters, P. gingivalis has the potential to promote host colonization and development of a pathogenic community.

Testing Multi-Task Cancer Evolution: How Do We Test Ecological Hypotheses in Cancer?

Recently several authors described a family of models, according to which different cancer types and subtypes fall within a space of selective trade-offs between archetypes that maximize the performance of different tasks: cell division, biomass and energy production, lipogenesis, immune interaction, and invasion and tissue remodeling. On this picture, inter- and intratumor heterogeneity can be explained in part as a product of these selective trade-offs in different cancers, at different stages of cancer progression. The aim of this Perspective is to critically assess this approach. I use this case study to consider more generally both the advantages of using ecological models in the context of cancer, and the challenges facing testing of such models.

Cancer metastasis as a non-healing wound

Most cancer deaths are caused by metastasis: recurrence of disease by disseminated tumour cells at sites distant from the primary tumour. Large numbers of disseminated tumour cells are released from the primary tumour, even during the early stages of tumour growth. However, only a minority survive as potential seeds for future metastatic outgrowths. These cells must adapt to a relatively inhospitable microenvironment, evade immune surveillance and progress from the micro- to macro-metastatic stage to generate a secondary tumour. A pervasive driver of this transition is chronic inflammatory signalling emanating from tumour cells themselves. These signals can promote migration and engagement of stem and progenitor cell function, events that are also central to a wound healing response. In this review, we revisit the concept of cancer as a non-healing wound, first introduced by Virchow in the 19th century, with a new tumour cell-intrinsic perspective on inflammation and focus on metastasis. Cellular responses to inflammation in both wound healing and metastasis are tightly regulated by crosstalk with the surrounding microenvironment. Targeting or restoring canonical responses to inflammation could represent a novel strategy to prevent the lethal spread of cancer.

EGF Induces Migration Independent of EMT or Invasion in A549 Lung Adenocarcinoma Cells

Tumors and the tumor microenvironment produce multiple growth factors that influence cancer cell behavior via various signal transduction pathways. Growth factors, like transforming growth factor β (TGFβ) and epidermal growth factor (EGF), have been shown to induce proliferation, migration, and invasion in different cell models. Both factors are frequently overexpressed in cancer and will often act in combination. Although both factors are being used as rational targets in clinical oncology, the similarities and differences of their contributions to cancer cell migration and invasion are not fully understood. Here we compared the impact of treating A549 lung adenocarcinoma cells with TGFβ, EGF, and both in combination by applying videomicroscopy, functional assays, immunoblotting, real-time PCR, and proteomics. Treatment with both factors stimulated A549 migration to a similar extent, but with different kinetics. The combination had an additive effect. EGF-induced migration depended on activation of the mitogen-activated protein kinase (MAPK) pathway. However, this pathway was dispensable for TGFβ-induced migration, despite a strong activation of this pathway by TGFβ. Proteome analysis (data are available via ProteomeXchange with identifier PXD023024) revealed an overlap in expression patterns of migration-related proteins and associated gene ontology (GO) terms by TGFβ and EGF. Further, only TGFβ induced the expression of epithelial to mesenchymal transition (EMT)-related proteins like matrix metalloproteinase 2 (MMP2). EGF, in contrast, made no major contribution to EMT marker expression on either the protein or the transcript level. In line with these expression patterns, TGFβ treatment significantly increased the invasive capacity of A549 cells, while EGF treatment did not. Moreover, the addition of EGF failed to enhance TGFβ-induced invasion. Overall, these data suggest that TGFβ and EGF can partly compensate for each other for stimulation of cell migration, but abrogation of TGFβ signaling may be more suitable to suppress cell invasion.

Diffuse Glioma Heterogeneity and Its Therapeutic Implications

Diffuse gliomas represent a heterogeneous group of universally lethal brain tumors characterized by minimally effective genotype-targeted therapies. Recent advances have revealed that a remarkable level of genetic, epigenetic, and environmental heterogeneity exists within each individual glioma. Together, these interconnected layers of intratumoral heterogeneity result in extreme phenotypic heterogeneity at the cellular level, providing for multiple mechanisms of therapeutic resistance and forming a highly adaptable and resilient disease. In this review, we discuss how glioma intratumoral heterogeneity and malignant cellular state plasticity drive resistance to existing therapies and look to a future in which these challenges may be overcome. SIGNIFICANCE: Glioma intratumoral heterogeneity and malignant cell state plasticity represent formidable hurdles to the development of novel targeted therapies. However, the convergence of genotypically diverse glioma cells into a limited set of epigenetically encoded transcriptional cell states may present an opportunity for a novel therapeutic strategy we call "State Selective Lethality." In this approach, cellular states (as opposed to genetic perturbations/mutations) are the subject of therapeutic targeting, and plasticity-mediated resistance is minimized through the design of cell state "trapping agents."

Receptor Tyrosine Kinase Signaling and Targeting in Glioblastoma Multiforme

Glioblastoma multiforme (GBM) is amongst the deadliest of human cancers, with a median survival rate of just over one year following diagnosis. Characterized by rapid proliferation and diffuse infiltration into the brain, GBM is notoriously difficult to treat, with tumor cells showing limited response to existing therapies and eventually developing resistance to these interventions. As such, there is intense interest in better understanding the molecular alterations in GBM to guide the development of more efficient targeted therapies. GBM tumors can be classified into several molecular subtypes which have distinct genetic signatures, and they show aberrant activation of numerous signal transduction pathways, particularly those connected to receptor tyrosine kinases (RTKs) which control glioma cell growth, survival, migration, invasion, and angiogenesis. There are also non-canonical modes of RTK signaling found in GBM, which involve G-protein-coupled receptors and calcium channels. This review uses The Cancer Genome Atlas (TCGA) GBM dataset in combination with a data-mining approach to summarize disease characteristics, with a focus on select molecular pathways that drive GBM pathogenesis. We also present a unique genomic survey of RTKs that are frequently altered in GBM subtypes, as well as catalog the GBM disease association scores for all RTKs. Lastly, we discuss current RTK targeted therapies and highlight emerging directions in GBM research.

CD44 expression in the tumor periphery predicts the responsiveness to bevacizumab in the treatment of recurrent glioblastoma

Antiangiogenic therapy with bevacizumab (Bev), a monoclonal antibody targeting vascular endothelial growth factor (VEGF), is a common treatment for recurrent glioblastoma (GBM), but its survival benefit is limited. Resistance to Bev is thought to be a major cause of ineffectiveness on Bev therapy. To optimize Bev therapy, identification of a predictive biomarker for responsiveness to Bev is required. Based on our previous study, we focused on the expression and functions of CD44 and VEGF in the Bev therapy. Here, we analyze a relationship between CD44 expression and responsiveness to Bev and elucidate the role of CD44 in anti‐VEGF therapy. CD44 and VEGF expression in the tumor core and periphery of 22 GBMs was examined, and the relationship between expression of these molecules and progression‐free time on Bev therapy was analyzed. The degree of CD44 expression in the tumor periphery was evaluated by the ratio of the mRNA expression in the tumor periphery to that in the tumor core (P/C ratio). VEGF expression was evaluated by the amount of the mRNA expression in the tumor periphery. To elucidate the roles of CD44 in the Bev therapy, in vitro and in vivo studies were performed using glioma stem‐like cells (GSCs) and a GSC‐transplanted mouse xenograft model, respectively. GBMs expressing high P/C ratio of CD44 were much more refractory to Bev than those expressing low P/C ratio of CD44, and the survival time of the former was much shorter than that of the latter. In vitro inhibition of VEGF with siRNA or Bev‐activated CD44 expression and increased invasion of GSCs. Bev showed no antitumor effects in mice transplanted with CD44‐overexpressing GSCs. The P/C ratio of CD44 expression may become a useful biomarker predicting responsiveness to Bev in GBM. CD44 reduces the antitumor effect of Bev, resulting in much more highly invasive tumors.

Systematic alteration of in vitro metabolic environments reveals empirical growth relationships in cancer cell phenotypes

Cancer cells, like microbes, live in complex metabolic environments. Recent evidence suggests that microbial behavior across metabolic environments is well described by simple empirical growth relationships, or growth laws. Do such empirical growth relationships also exist in cancer cells? To test this question, we develop a high-throughput approach to extract quantitative measurements of cancer cell behaviors in systematically altered metabolic environments. Using this approach, we examine relationships between growth and three frequently studied cancer phenotypes: drug-treatment survival, cell migration, and lactate overflow. Drug-treatment survival follows simple linear growth relationships, which differ quantitatively between chemotherapeutics and EGFR inhibition. Cell migration follows a weak grow-and-go growth relationship, with substantial deviation in some environments. Finally, lactate overflow is mostly decoupled from growth rate and is instead determined by the cells’ ability to maintain high sugar uptake rates. Altogether, this work provides a quantitative approach for formulating empirical growth laws of cancer.

Kochanowski et al. quantify cancer cell phenotypes across systematically altered in vitro metabolic environments to search for phenotype-growth relationships, similar to the growth laws found in microbes. Three case studies highlight examples in which such growth relationships are clearly operating (cancer drug survival), weakly present (cell migration), or absent (lactate overflow).