A computational model incorporating neural stem cell dynamics reproduces glioma incidence across the lifespan in the human population

A Structural Characterisation of the Mitogen-Activated Protein Kinase Network in Cancer

Gene regulatory networks represent collections of regulators that interact with each other and with other molecules to govern gene expression. Biological signalling networks model how signals are transmitted and how activities are coordinated in the cell. The study of the structure of such networks in complex diseases such as cancer can provide insights into how they function, and consequently, suggest suitable treatment approaches. Here, we explored such topological characteristics in the example of a mitogen-activated protein kinase (MAPK) signalling network derived from published studies in cancer. We employed well-established techniques to conduct network analyses, and collected information on gene function as obtained from large-scale public databases. This allowed us to map topological and functional relationships, and build hypotheses on this network’s functional consequences. In particular, we find that the topology of this MAPK network is highly non-random, modular and robust. Moreover, analysis of the network’s structure indicates the presence of organisational features of cancer hallmarks, expressed in an asymmetrical manner across communities of the network. Finally, our results indicate that the organisation of this network renders it problematic to use treatment approaches that focus on a single target. Our analysis suggests that multi-target attacks in a well-orchestrated manner are required to alter how the network functions. Overall, we propose that complex network analyses combined with pharmacological insights will help inform on future treatment strategies, exploiting structural vulnerabilities of signalling and regulatory networks in cancer.

The Multiple Dimensions of Networks in Cancer: A Perspective

This perspective article gathers the latest developments in mathematical and computational oncology tools that exploit network approaches for the mathematical modelling, analysis, and simulation of cancer development and therapy design. It instigates the community to explore new paths and synergies under the umbrella of the Special Issue “Networks in Cancer: From Symmetry Breaking to Targeted Therapy”. The focus of the perspective is to demonstrate how networks can model the physics, analyse the interactions, and predict the evolution of the multiple processes behind tumour-host encounters across multiple scales. From agent-based modelling and mechano-biology to machine learning and predictive modelling, the perspective motivates a methodology well suited to mathematical and computational oncology and suggests approaches that mark a viable path towards adoption in the clinic.

Calcium Channels in Adult Brain Neural Stem Cells and in Glioblastoma Stem Cells

The brain of adult mammals, including humans, contains neural stem cells (NSCs) located within specific niches of which the ventricular-subventricular zone (V-SVZ) is the largest one. Under physiological conditions, NSCs proliferate, self-renew and produce new neurons and glial cells. Several recent studies established that oncogenic mutations in adult NSCs of the V-SVZ are responsible for the emergence of malignant primary brain tumors called glioblastoma. These aggressive tumors contain a small subpopulation of cells, the glioblastoma stem cells (GSCs), that are endowed with proliferative and self-renewal abilities like NSCs from which they may arise. GSCs are thus considered as the cells that initiate and sustain tumor growth and, because of their resistance to current treatments, provoke tumor relapse. A growing body of studies supports that Ca²⁺ signaling controls a variety of processes in NSCs and GSCs. Ca²⁺ is a ubiquitous second messenger whose fluctuations of its intracellular concentrations are handled by channels, pumps, exchangers, and Ca²⁺ binding proteins. The concerted action of the Ca²⁺ toolkit components encodes specific Ca²⁺ signals with defined spatio-temporal characteristics that determine the cellular responses. In this review, after a general overview of the adult brain NSCs and GSCs, we focus on the multiple roles of the Ca²⁺ toolkit in NSCs and discuss how GSCs hijack these mechanisms to promote tumor growth. Extensive knowledge of the role of the Ca²⁺ toolkit in the management of essential functions in healthy and pathological stem cells of the adult brain should help to identify promising targets for clinical applications.

Silencing of PRDM5 increases cell proliferation and inhibits cell apoptosis in glioma

AIM

PR-domain-containing 5 (PRDM5), a family member of PR-domain-containing zinc finger genes, has been reported to participate in modulate cellular processes, including cell growth, differentiation and apoptosis. It has also been found to function as a putative tumor suppressor in different types of cancer. The present study is the first, to the best of our knowledge, to report on the clinical significance of the expression of PRDM5 in glioma cell line.

MATERIALS AND METHODS

Western blot analyse the expression of PRDM5 in glioma tissues and cells. 80 tissues microarray samples from patients with glioma were examined using immunohistochemical analysis. Glioblastoma U251 cells were transfected with PRDM5-siRNA and control-siRNA. U251cell proliferation was measured by flow cytometric analysis and plate colony formation assay. Cell apoptosis were detected using flow cytometric analysis.

RESULTS

The results of western blot analysis and immunohistochemistry showed that the expression of PRDM5 was decreased in fresh glioma tissues, compared with that in normal brain tissues. Kaplan-Meier postoperative survival curves demonstrated that the low expression of PRDM5 was associated with poor prognosis in patients with glioma. In addition, suppression of PRDM5 promoted cell proliferation via regulating cell cycle progression. Finally, knocking down PRDM5 using small interfering RNA decreased the apoptosis of glioma cells.

CONCLUSION

Taken together, these findings suggested that PRDM5 may be a novel therapeutic target of glioma.

An in silico hybrid continuum-/agent-based procedure to modelling cancer development: Interrogating the interplay amongst glioma invasion, vascularity and necrosis

This paper develops a three-dimensional in silico hybrid model of cancer, which describes the multi-variate phenotypic behaviour of tumour and host cells. The model encompasses the role of cell migration and adhesion, the influence of the extracellular matrix, the effects of oxygen and nutrient availability, and the signalling triggered by chemical cues and growth factors. The proposed in silico hybrid modelling framework combines successfully the advantages of continuum-based and discrete methods, namely the finite element and agent-based method respectively. The framework is thus used to realistically model cancer mechano-biology in a multiscale fashion while maintaining the resolution power of each method in a computationally cost-effective manner. The model is tailored to simulate glioma progression, and is subsequently used to interrogate the balance between the host cells and small sized gliomas, while the go-or-grow phenotype characteristic in glioblastomas is also investigated. Also, cell-cell and cell-matrix interactions are examined with respect to their effect in (macroscopic) tumour growth, brain tissue perfusion and tumour necrosis. Finally, we use the in silico framework to assess differences between low-grade and high-grade glioma growth, demonstrating significant differences in the distribution of cancer as well as host cells, in accordance with reported experimental findings.

Interaction with AEG-1 and MDM2 is associated with glioma development and progression and correlates with poor prognosis

Glioma is the most common central nervous system tumor with poor prognosis. The AEG-1 (Astrocyte Elevated Gene 1) gene displays oncogenic characteristics, including proliferation, metastasis, chemoresistance, invasion, and evasion of apoptosis, and is strongly linked to the occurrence of glioma. Here, we elucidated the potential contribution of AEG-1 in human glioma pathogenesis. In glioma cells, AEG-1 could directly interact with Murine Double Minute-2 (MDM2) protein resulting in MDM2-p53-mediated cell proliferation and apoptosis. MDM2 is being revealed as an oncoprotein, which is involved in many human cancers progression. By immunohistochemical and a multivariate analysis, expressions of AEG-1 and MDM2 were elevated in glioma and high AEG-1 and MDM2 expressions were showed to be correlated with poor prognosis. AEG-1-MDM2 interaction prolonged stabilization of MDM2 where AEG-1 inhibited ubiquitination and subsequent proteasome-mediated degradation of MDM2 protein. Moreover, slicing AEG-1 blocked MDM2 expression and then impacted MDM2-p53 pathway that influenced cell proliferation and apoptosis. These findings uncover a novel AEG-1-MDM2 interplay by which AEG-1 augments glioma progression and reveal a viable potential therapy for the treatment of glioma patients.

MicroRNA-370 suppresses the progression and proliferation of human astrocytoma and glioblastoma by negatively regulating β-catenin and causing activation of FOXO3a

Certain microRNAs (miRs) regulate the progression and metastasis of various cancer types. In the present study, the role of miR-370 in the progression and proliferation of human astrocytoma and glioblastoma cells was assessed and the underlying molecular mechanism was investigated. miR-370 levels in clinical specimens of human glioma and peritumoral tissues were determined by reverse-transcription quantitative PCR. Oligonucleotide mimics and inhibitors were transfected into the U-251MG human astrocytoma cell line and the and U-87MG glioblastoma cell line and the cell viability of was determined by an MTT assay. The expression of β-catenin and forkhead box protein (FOX)O3a was determined by western blot analysis. The results revealed that the expression of miR-370 in human glioma tissues was significantly decreased compared with that in peritumoral tissues. The miR-370 levels in patients with grade III/IV gliomas were significantly decreased compared with those in grade I/II. Transfection with miR-370 mimics inhibited the proliferation of U-251MG and U-87MG cells. Furthermore, the miR-370 levels were negatively correlated with β-catenin and positively correlated with nuclear FOXO3a. In conclusion, miR-370 inhibited the proliferation of human glioma cells by regulating the levels of β-catenin and the activation of FOXO3a, suggesting that miR-370 was a tumor suppressor in the progression of human astrocytoma and glioblastoma cells.

High expression of VRK1 is related to poor prognosis in glioma

Vaccinia-related kinase 1 (VRK1) is a member of the vaccinia-related kinase (VRK) family of serine/threonine protein kinases, which phosphorylates several transcription factors and has been postulated to be involved in regulation of cell proliferation. However, it remains unclear whether aberrant expression of VRK1 is related to the development of glioma. In this study, we aimed to investigate the clinical significance of VRK1 expression in human glioma and its biological function in glioma cells. Western blot and immunohistochemical analysis revealed that VRK1 was highly expressed in glioma tissues and cell lines. In addition, the expression level of VRK1 was positively correlated with glioma pathological grade, as well as Ki-67 expression. Kaplan-Meier analysis revealed that patients with high VRK1 expression was associated with a poorer prognosis. To determine whether VRK1 could regulate the proliferation of glioma cells, we transfected glioma cells with interfering RNA target VRK1, then investigated cell proliferation with cell counting kit (CCK) -8, flow cytometry assays and colony formation analyses. Our results indicated that knockdown of VRK1 would inhibit the proliferation of glioma cells. Besides, reduced expression of VRK1 could induce the apoptosis of glioma cells. On the basis of these findings, we suggested that VRK1 might be a promising prognostic biomarker of glioma.

Up-regulation of plakophilin-2 is correlated with the progression of glioma

Glioma is the most common type of primary brain tumor in the CNS. Due to its poor prognosis and high mortality rates, it is urgent to find out more effective therapies. Plakophilin-2 (PKP2) is a widespread desmosomal plaque protein. Recently, the important roles of PKP2 in the proliferation and migration of cancer cells and tumor progression has been shown. However, the expression and potential function of PKP2 in glioma was still unclear. In this study, we demonstrated that PKP2 protein expression level was increased in glioma tissues compared with normal brain tissues, and its level was significantly associated with the Ki-67 expression and WHO grade by Western blot analysis and immunohistochemistry. Clinically, high PKP2 expression was tightly related to poor prognosis of glioma patients. Interestingly, we found that down-regulated PKP2 expression was shown to inhibit the migration of cells in glioma. Moreover, cell counting kit (CCK)-8 and colony formation analyses proved that reduced expression of PKP2 could weaken glioma cell proliferation. Taken together, these data uncover a potential role for PKP2 in the pathogenic process of glioma, suggesting that PKP2 may be a promising therapeutic target of glioma.

Expression of CDC5L is associated with tumor progression in gliomas

Cell division cycle 5-like (CDC5L) protein is a cell cycle regulator of the G2/M transition and has been reported to participate in the catalytic step of pre-messenger RNA (mRNA) splicing and DNA damage repair. Recently, it was also found to act as a candidate oncogene in osteosarcoma and cervical tumors. However, the role of CDC5L expression in tumor biology was still unclear. Here, we analyzed the expression and clinical significance of CDC5L in gliomas. The expression of CDC5L in fresh glioma tissues and paraffin-embedded slices was evaluated by western blot and immunohistochemistry, respectively. We found that CDC5L was highly expressed in glioma tissues. The expression of CDC5L was significantly associated with glioma pathology grade and Ki-67 expression. Univariate and multivariate analyses showed that high CDC5L expression was an independent prognostic factor for glioma patients' survival. To determine whether CDC5L could regulate the proliferation of glioma cells, we transfected glioma cells with interfering RNA target CDC5L, then investigated cell proliferation with cell counting kit (CCK)-8, flow cytometry assays and colony formation analyses. Our results indicated that knockdown of CDC5L would inhibit proliferation of glioma cells. Besides, reduced expression of CDC5L could induce the apoptosis of glioma cells. These findings suggested that CDC5L might play an important role in glioma and thus be a promising therapeutic target of glioma.