Junghwa Cha

Strategies of Mesenchymal Invasion of Patient-derived Brain Tumors: Microenvironmental Adaptation

The high mortality in glioblastoma multiforme (GBM) patients is primarily caused by extensive infiltration into adjacent tissue and subsequent rapid recurrence. There are no clear therapeutic strategies that target the infiltrative subpopulation of GBM mass. Using mesenchymal mode of invasion, the GBM is known to widely infiltrate by interacting with various unique components within brain microenvironment such as hyaluronic acid (HA)-rich matrix and white matter tracts. However, it is unclear how these GBM microenvironments influence the strategies of mesenchymal invasion. We hypothesize that GBM has different strategies to facilitate such invasion through adaptation to their local microenvironment. Using our in vitro biomimetic microenvironment platform for three-dimensional GBM tumorspheres (TSs), we found that the strategies of GBM invasion were predominantly regulated by the HA-rich ECM microenvironment, showing marked phenotypic changes in the presence of HA, which were mainly mediated by HA synthase (HAS). Interestingly, after inhibition of the HAS gene, GBM switched their invasion strategies to a focal adhesion (FA)-mediated invasion. These results demonstrate that the microenvironmental adaptation allowed a flexible invasion strategy for GBM. Using our model, we suggest a new inhibitory pathway for targeting infiltrative GBM and propose an importance of multi-target therapy for GBM, which underwent microenvironmental adaptation.

Tapered Microtract Array Platform for Antimigratory Drug Screening of Human Glioblastoma Multiforme

Understanding the effects of topographic characteristics on tumor cell migration is important for the development of new anti-migratory therapies. However, simplified in vitro culture systems often lead to inaccurate results regarding the efficacy of drugs. Histopathologically, glioblastoma multiform (GBM) cells migrate along the orientation of thin, elongated anatomical structures, such as white-matter tracts. Here, a tapered microtract array platform which mimics the anatomical features of brain tissue is introduced. This platform enables optimization of design for platform fabrication depending on topographic effects. By monitoring the migration of GBM cells on a simple tapered microtract, a saltatory migration resembling the migratory phenotype of human GBM cells in vivo is observed. The platform effectively induces the native characteristics and behavior of cells by topographic cues, allowing to observe the critical point for crawling to saltatory transition. Furthermore, this platform can be applied to efficiently screen anti-cancer drug by inhibiting associated signaling pathways on GBM cells. In conclusion, the microtract array platform reported here may provide a better understanding of the effects of topographic characteristics on cell migration, and may also be useful to determine the efficacy of antimigratory drugs for glioblastoma cells with cellular and molecular research and high-throughput screening.

The mode and dynamics of glioblastoma cell invasion into a decellularized tissue-derived extracellular matrix-based three-dimensional tumor model

Glioblastoma multiforme (GBM) is the most common brain tumor with very aggressive and infiltrative. Extracellular matrix (ECM) plays pivotal roles in the infiltrative characteristics of GBM. To understand the invasive characteristic of GBM, it is necessary to study cell-ECM interaction in the physiologically relevant biomimetic model that recapitulates the GBM-specific ECM microenvironment. Here, we propose biomimetic GBM-specific ECM microenvironment for studying mode and dynamics of glioblastoma cell invasion. Using tissue decellularization process, we constructed a patient tissue-derived ECM (pdECM)-based three-dimensional in vitro model. In our model, GBM cells exhibited heterogeneous morphology and altered the invasion routes in a microenvironment-adaptive manner. We further elucidate the effects of inhibition of ECM remodeling-related enzymatic activity (Matrix metalloproteinase (MMP) 2/9, hyaluronan synthase (HAS)) on GBM cell invasion. Interestingly, after blocking both enzyme activity, GBM cells underwent morphological transition and switch the invasion mode. Such adaptability could render cell invasion resistant to anti-cancer target therapy. There results provide insight of how organ-specific matrix differentially regulates cancer cell phenotype, and have significant implications for the design of matrix with appropriate physiologically relevant properties for in vitro tumor model.

Biomimetic strategies for the glioblastoma microenvironment

Glioblastoma multiforme (GBM) is a devastating type of tumor with high mortality, caused by extensive infiltration into adjacent tissue and rapid recurrence. Most therapies for GBM have focused on the cytotoxicity, and have not targeted GBM spread. However, there have been numerous attempts to improve therapy by addressing GBM invasion, through understanding and mimicking its behavior using three-dimensional (3D) experimental models. Compared with two-dimensional models and in vivo animal models, 3D GBM models can capture the invasive motility of glioma cells within a 3D environment comprising many cellular and non-cellular components. Based on tissue engineering techniques, GBM invasion has been investigated within a biologically relevant environment, from biophysical and biochemical perspectives, to clarify the pro-invasive factors of GBM. This review discusses the recent progress in techniques for modeling the microenvironments of GBM tissue and suggests future directions with respect to recreating the GBM microenvironment and preclinical applications.

Nanoengineered, cell-derived extracellular matrix influences ECM-related gene expression of mesenchymal stem cells

BackgroundHuman mesenchymal stem cells (hMSCs) are, due to their pluripotency, useful sources of cells for stem cell therapy and tissue regeneration. The phenotypes of hMSCs are strongly influenced by their microenvironment, in particular the extracellular matrix (ECM), the composition and structure of which are important in regulating stem cell fate. In reciprocal manner, the properties of ECM are remodeled by the hMSCs, but the mechanism involved in ECM remodeling by hMSCs under topographical stimulus is unclear. In this study, we therefore examined the effect of nanotopography on the expression of ECM proteins by hMSCs by analyzing the quantity and structure of the ECM on a nanogrooved surface.MethodsTo develop the nanoengineered, hMSC-derived ECM, we fabricated the nanogrooves on a coverglass using a UV-curable polyurethane acrylate (PUA). Then, hMSCs were cultivated on the nanogrooves, and the cells at the full confluency were decellularized. To analyze the effect of nanotopography on the hMSCs, the hMSCs were re-seeded on the nanoengineered, hMSC-derived ECM.ResultshMSCs cultured within the nano-engineered hMSC-derived ECM sheet showed a different pattern of expression of ECM proteins from those cultured on ECM-free, nanogrooved surface. Moreover, hMSCs on the nano-engineered ECM sheet had a shorter vinculin length and were less well-aligned than those on the other surface. In addition, the expression pattern of ECM-related genes by hMSCs on the nanoengineered ECM sheet was altered. Interestingly, the expression of genes for osteogenesis-related ECM proteins was downregulated, while that of genes for chondrogenesis-related ECM proteins was upregulated, on the nanoengineered ECM sheet.ConclusionsThe nanoengineered ECM influenced the phenotypic features of hMSCs, and that hMSCs can remodel their ECM microenvironment in the presence of a nanostructured ECM to guide differentiation into a specific lineage.

Mild Reduction of the Cancer Cell Surface as an Anti-invasion Treatment

Cancer cell invasion is the main reason for high mortality in patients with malignant cancers. There has been little improvement in cancer prognosis because of a high rate of infiltration. Therefore, successful treatment requires inhibition of cancer cell invasion. Here, we suggest a new approach to inhibit cancer cell invasion through mild reduction of cell surface proteins to expose free thiols. Through mild reduction, the cancer cell surfaces present free active thiols at the membranes, enhancing cell adhesion to extracellular matrix and decreasing motility. Collectively, we suggest cell surface modification as a new therapeutic approach to treat invading malignant cancers.