Biological characterization of the UW402, UW473, ONS-76 and DAOY pediatric medulloblastoma cell lines

Comparative analysis of pediatric SHH medulloblastoma DAOY spheres and adherent monolayers: implications for medulloblastoma research

Medulloblastoma, the most prevalent brain tumor among children, requires a comprehensive understanding of its cellular characteristics for effective research and treatment. In this study, we focused on DAOY, a permanent cell line of medulloblastoma, and investigated the unique properties of DAOY cells when cultured as floating multicellular aggregates called spheres, as opposed to adherent monolayers. Through our comprehensive analysis, we identified distinct characteristics associated with DAOY spheres. Our findings demonstrate that DAOY spheres express markers for both neural stem cells, such as CD133 (PROM1), and differentiated neurons, exemplified by MAP2. Additionally, our investigation revealed that spheres-derived cells exhibit heightened resistance to ionizing radiation compared to adherent cells. Consequently, our results indicate that caution is advised when interpreting experimental results obtained from adherent cell cultures and extrapolating them to in vivo situations.

Engineering subarachnoid trabeculae with electrospun poly(caprolactone) (PCL) scaffolds to study leptomeningeal metastasis in medulloblastoma

Leptomeningeal metastasis (LM) occurs when cancer cells infiltrate the subarachnoid space (SAS) and metastasize to the fibrous structures that surround the brain and spinal cord. These structures include the leptomeninges (i.e., the pia mater and arachnoid mater), as well as subarachnoid trabeculae, which are collagen-rich fibers that provide mechanical structure for the SAS, support resident cells, and mediate flow of cerebrospinal fluid (CSF). Although there is a strong expectation that the presence of fibers within the SAS influences LM to be a major driver of tumor progression and lethality, exactly how trabecular architecture relates to the process of metastasis in cancer is poorly understood. This lack of understanding is likely due in part to the difficulty of accessing and manipulating this tissue compartment in vivo. Here, we utilized electrospun polycaprolactone (PCL) to produce structures bearing remarkable morphological similarity to native SAS fiber architecture. First, we profiled the native architecture of leptomeningeal and trabecular fibers collected from rhesus macaque monkeys, evaluating both qualitative and quantitative differences in fiber ultrastructure for various regions of the CNS. We then varied electrospinning parameters to produce a small library of PCL scaffolds possessing distinct architectures mimicking the range of fiber properties observed in vivo. For proof of concept, we studied the metastasis-related behaviors of human pediatric medulloblastoma cells cultured in different fiber microenvironments. These studies demonstrated that a more open, porous fiber structure facilitates DAOY cell spread across and infiltration into the meningeal mimic. Our results present a new tissue engineered model of the subarachnoid space and affirm the expectation that fiber architecture plays an important role in mediating metastasis-related behaviors in an in vitro model of pediatric medulloblastoma.

Curcumin analogue BDDD-721 exhibits more potent anticancer effects than curcumin on medulloblastoma by targeting Shh/Gli1 signaling pathway

Medulloblastoma (MB) is a malignant tumor in the fourth ventricle of children. The clinical treatment is mainly surgical resection combined with radiotherapy and chemotherapy, but the curative effect is not ideal, and the 3-year survival rate is very low. Previous study confirmed that curcumin attenuated the proliferation of medulloblastoma both in vitro and in vivo. In present study, we found a curcumin analogue named BDDD-721, exhibited more potent anti-tumor activity than curcumin. Compared with curcumin, BDDD-721 more effectively inhibited the proliferation, migration, invasion, and increased apoptosis of medulloblastoma cells. Furthermore, BDDD-721 treatment led to activation of glioma-associated oncogene homolog (Gli), reduced expression of Shh and its downstream target Smo, Gli1 and Ptch1. In addition, SAG (Shh signaling pathway agonist) antagonized the pro-apoptotic effects of BDDD-721 on medulloblastomas as confirmed by CCK8 assays and flow cytometry; while cyclopamine (Shh signaling pathway inhibitor) enhanced its effects on medulloblastomas. In conclusion, these results indicate that curcumin analogue BDDD-721 has more potent anticancer effects than curcumin on medulloblastomas by targeting Shh/Gli1 signaling pathway.

Type-I Collagen/Collagenase Modulates the 3D Structure and Behavior of Glioblastoma Spheroid Models

Multicellular tumor spheroids have emerged as well-structured, three-dimensional culture models that resemble and mimic the complexity of the dense and hypoxic cancer microenvironment. However, in brain tumor studies, a variety of glioblastoma multiforme (GBM) cell lines only self-assemble into loose cellular aggregates, lacking the properties of actual glioma tumors in humans. In this study, we used type-I collagen as an extracellular matrix component to promote the compaction of GBM aggregates forming tight spheroids to understand how collagen influences the properties of tumors, such as their growth, proliferation, and invasion, and collagenase to promote collagen degradation. The GBM cell lines U87MG, T98G, and A172, as well as the medulloblastoma cell line UW473, were used as standard cell lines that do not spontaneously self-assemble into spheroids, and GBM U251 was used as a self-assembling cell line. According to the findings, all cell lines formed tight spheroids at collagen concentrations higher than 15.0 μg mL^-1. Collagen was distributed along the spheroid, similarly to that observed in invasive GBM tumors, and decreased cell migration with no effect on the cellular uptake of small active molecules, as demonstrated by uptake studies using the photosensitizer verteporfin. The enzymatic cleavage of collagen affected spheroid morphology and increased cell migration while maintaining cell viability. Such behaviors are relevant to the physiological models of GBM tumors and are useful for better understanding cell migration and the in vivo infiltration path, drug screening, and kinetics of progression of GBM tumors.

3D spheroid models of paediatric SHH medulloblastoma mimic tumour biology, drug response and metastatic dissemination

Studying medulloblastoma, the most common malignant paediatric brain tumour, requires simple yet realistic in vitro models. In this study, we optimised a robust, reliable, three-dimensional (3D) culture method for medulloblastoma able to recapitulate the spatial conformation, cell-cell and cell-matrix interactions that exist in vivo and in patient tumours. We show that, when grown under the same stem cell enriching conditions, SHH subgroup medulloblastoma cell lines established tight, highly reproducible 3D spheroids that could be maintained for weeks in culture and formed pathophysiological oxygen gradients. 3D spheroid culture also increased resistance to standard-of-care chemotherapeutic drugs compared to 2D monolayer culture. We exemplify how this model can enhance in vitro therapeutic screening approaches through dual-inhibitor studies and continual monitoring of drug response. Next, we investigated the initial stages of metastatic dissemination using brain-specific hyaluronan hydrogel matrices. RNA sequencing revealed downregulation of cell cycle genes and upregulation of cell movement genes and key fibronectin interactions in migrating cells. Analyses of these upregulated genes in patients showed that their expression correlated with early relapse and overall poor prognosis. Our 3D spheroid model is a significant improvement over current in vitro techniques, providing the medulloblastoma research community with a well-characterised and functionally relevant culture method.

RBM5 Acts as Tumor Suppressor in Medulloblastoma through Regulating Wnt/β-Catenin Signaling

INTRODUCTION

RBM5 acts as a tumor suppressor gene in lung and breast cancers; however, its role in the pathogenesis of medulloblastoma (MB) remains unclear. We previously identified 4 RBM5 mutations in whole exome sequencing analysis of 40 MB patients. This study examined the role of RBM5 in MB progression.

METHODS

The expression patterns of RBM5 in tissues of 40 MB patients were analyzed using immunohistochemistry. Associations between RBM5 expression and overall survival (OS) were evaluated using Kaplan-Meier analysis. The RBM5 role in Daoy cells' proliferation, migration, and Wnt/β-catenin signaling was analyzed after RBM5 knockdown and overexpression.

RESULTS

The expression level of RBM5 mRNA and protein was significantly lower in MB than that in adjacent normal control tissues, and low RBM5 expression was significantly associated with reduced OS (p = 0.034). RBM5 knockdown induced Daoy and ONS-76 cells proliferation, while RBM5 overexpression repressed cell proliferation and migration in vitro (all p < 0.05). β-Catenin, LEF1, and cyclin D1 mRNA levels were upregulated, while DKK1 expression was downregulated in Daoy cells following RBM5 knockdown.

CONCLUSION

RBM5 may function as a tumor suppressor in MB by regulating Wnt/β-catenin signaling, and its reduced expression is associated with lower OS.

Geniposide exhibits anticancer activity to medulloblastoma cells by downregulating microRNA-373

BACKGROUND

Medulloblastoma is a common tumor originates from central nervous system in children with metastatic potential. Geniposide is the major active ingredient separated from the fruit of Gardenia jasminoides Ellis. Herein, we tested the possible anticancer activity of geniposide on human medulloblastoma cells, as well as the potential underlying molecular mechanisms.

METHODS

Firstly, followed by geniposide incubation, cell viability, proliferation, apoptosis, migration, and invasion of medulloblastoma Daoy cells, along with microRNA-373 (miR-373) expression were tested, respectively. Then, the influences of miR-373 overexpression in the reduction of medulloblastoma cell proliferation, migration, and invasion and the elevation of apoptosis, triggered by geniposide treatment, were re-investigated. Finally, the Ras/Raf/MEK/ERK pathway activity was analyzed.

RESULTS

Geniposide treatment inhibited medulloblastoma cell viability, proliferation, migration, and invasion, but promoted cell apoptosis. Surprisingly, miR-373 expression in medulloblastoma cells was obviously downregulated by geniposide treatment. miR-373 overexpression reversed the effects of geniposide on Daoy cells. Furthermore, geniposide hindered the Ras/Raf/MEK/ERK pathway by downregulating miR-373 expression.

CONCLUSION

Geniposide exhibited anticancer activity on human medulloblastoma cells and blocked Ras/Raf/MEK/ERK pathway by downregulating miR-373 expression.

HDAC and MAPK/ERK Inhibitors Cooperate To Reduce Viability and Stemness in Medulloblastoma

Medulloblastoma (MB), which originates from embryonic neural stem cells (NSCs) or neural precursors in the developing cerebellum, is the most common malignant brain tumor of childhood. Recurrent and metastatic disease is the principal cause of death and may be related to resistance within cancer stem cells (CSCs). Chromatin state is involved in maintaining signaling pathways related to stemness, and inhibition of histone deacetylase enzymes (HDAC) has emerged as an experimental therapeutic strategy to target this cell population. Here, we observed antitumor actions and changes in stemness induced by HDAC inhibition in MB. Analyses of tumor samples from patients with MB showed that the stemness markers BMI1 and CD133 are expressed in all molecular subgroups of MB. The HDAC inhibitor (HDACi) NaB reduced cell viability and expression of BMI1 and CD133 and increased acetylation in human MB cells. Enrichment analysis of genes associated with CD133 or BMI1 expression showed mitogen-activated protein kinase (MAPK)/ERK signaling as the most enriched processes in MB tumors. MAPK/ERK inhibition reduced expression of the stemness markers, hindered MB neurosphere formation, and its antiproliferative effect was enhanced by combination with NaB. These results suggest that combining HDAC and MAPK/ERK inhibitors may be a novel and more effective approach in reducing MB proliferation when compared to single-drug treatments, through modulation of the stemness phenotype of MB cells.