Characterization of glioma stem-like cells from human glioblastomas

Cellular Components of the Tumor Environment in Gliomas-What Do We Know Today?

A generation ago, the molecular properties of tumor cells were the focus of scientific interest in oncology research. Since then, it has become increasingly apparent that the tumor environment (TEM), whose major components are non-neoplastic cell types, is also of utmost importance for our understanding of tumor growth, maintenance and resistance. In this review, we present the current knowledge concerning all cellular components within the TEM in gliomas, focusing on their molecular properties, expression patterns and influence on the biological behavior of gliomas. Insight into the TEM of gliomas has expanded considerably in recent years, including many aspects that previously received only marginal attention, such as the phenomenon of phagocytosis of glioma cells by macrophages and the role of the thyroid-stimulating hormone on glioma growth. We also discuss other topics such as the migration of lymphocytes into the tumor, phenotypic similarities between chemoresistant glioma cells and stem cells, and new clinical approaches with immunotherapies involving the cells of TEM.

Learning cell identity in immunology, neuroscience, and cancer

Suspension and imaging cytometry techniques that simultaneously measure hundreds of cellular features are powering a new era of cell biology and transforming our understanding of human tissues and tumors. However, a central challenge remains in learning the identities of unexpected or novel cell types. Cell identification rubrics that could assist trainees, whether human or machine, are not always rigorously defined, vary greatly by field, and differentially rely on cell intrinsic measurements, cell extrinsic tissue measurements, or external contextual information such as clinical outcomes. This challenge is especially acute in the context of tumors, where cells aberrantly express developmental programs that are normally time, location, or cell-type restricted. Well-established fields have contrasting practices for cell identity that have emerged from convention and convenience as much as design. For example, early immunology focused on identifying minimal sets of protein features that mark individual, functionally distinct cells. In neuroscience, features including morphology, development, and anatomical location were typical starting points for defining cell types. Both immunology and neuroscience now aim to link standardized measurements of protein or RNA to informative cell functions such as electrophysiology, connectivity, lineage potential, phospho-protein signaling, cell suppression, and tumor cell killing ability. The expansion of automated, machine-driven methods for learning cell identity has further created an urgent need for a harmonized framework for distinguishing cell identity across fields and technology platforms. Here, we compare practices in the fields of immunology and neuroscience, highlight concepts from each that might work well in the other, and propose ways to implement these ideas to study neural and immune cell interactions in brain tumors and associated model systems.

Electrotherapies for Glioblastoma

Non-thermal, intermediate frequency (100-500 kHz) electrotherapies present a unique therapeutic strategy to treat malignant neoplasms. Here, pulsed electric fields (PEFs) which induce reversible or irreversible electroporation (IRE) and tumour-treating fields (TTFs) are reviewed highlighting the foundations, advances, and considerations of each method when applied to glioblastoma (GBM). Several biological aspects of GBM that contribute to treatment complexity (heterogeneity, recurrence, resistance, and blood-brain barrier(BBB)) and electrophysiological traits which are suggested to promote glioma progression are described. Particularly, the biological responses at the cellular and molecular level to specific parameters of the electrical stimuli are discussed offering ways to compare these parameters despite the lack of a universally adopted physical description. Reviewing the literature, a disconnect is found between electrotherapy techniques and how they target the biological complexities of GBM that make treatment difficult in the first place. An attempt is made to bridge the interdisciplinary gap by mapping biological characteristics to different methods of electrotherapy, suggesting important future research topics and directions in both understanding and treating GBM. To the authors' knowledge, this is the first paper that attempts an in-tandem assessment of the biological effects of different aspects of intermediate frequency electrotherapy methods, thus offering possible strategies toward GBM treatment.

Molecular analyses of glioblastoma stem-like cells and glioblastoma tissue

Glioblastoma is a common, malignant brain tumor whose disease incidence increases with age. Glioblastoma stem-like cells (GSCs) are thought to contribute to cancer therapy resistance and to be responsible for tumor initiation, maintenance, and recurrence. This study utilizes both SNP array and gene expression profiling to better understand GSCs and their relation to malignant disease. Peripheral blood and primary glioblastoma tumor tissue were obtained from patients, the latter of which was used to generate GSCs as well as a CD133^pos./CD15^pos. subpopulation. The stem cell features of GSCs were confirmed via the immunofluorescent expression of Nestin, SOX2, and CD133. Both tumor tissue and the isolated primary cells shared unique abnormal genomic characteristics, including a gain of chromosome 7 as well as either a partial or complete loss of chromosome 10. Individual genomic differences were also observed, including the loss of chromosome 4 and segmental uniparental disomy of 9p24.3→p21.3 in GSCs. Gene expression profiling revealed 418 genes upregulated in tumor tissue vs. CD133^pos./CD15^pos. cells and 44 genes upregulated in CD133^pos./CD15^pos. cells vs. tumor tissue. Pathway analyses demonstrated that upregulated genes in CD133^pos./CD15^pos. cells are relevant to cell cycle processes and cancerogenesis. In summary, we detected previously undescribed genomic and gene expression differences when comparing tumor tissue and isolated stem-like subpopulations.

Abuhamad A, Syahir A. Understanding Glioblastoma Biomarkers: Knocking a Mountain with a Hammer

Gliomas are the most frequent and deadly form of human primary brain tumors. Among them, the most common and aggressive type is the high-grade glioblastoma multiforme (GBM), which rapidly grows and renders patients a very poor prognosis. Meanwhile, cancer stem cells (CSCs) have been determined in gliomas and play vital roles in driving tumor growth due to their competency in self-renewal and proliferation. Studies of gliomas have recognized CSCs via specific markers. This review comprehensively examines the current knowledge of the most significant CSCs markers in gliomas in general and in glioblastoma in particular and specifically focuses on their outlook and importance in gliomas CSCs research. We suggest that CSCs should be the superior therapeutic approach by directly targeting the markers. In addition, we highlight the association of these markers with each other in relation to their cascading pathways, and interactions with functional miRNAs, providing the role of the networks axes in glioblastoma signaling pathways.

Novel ablation methods for treatment of gliomas

Primary brain tumors are among the deadliest cancers that remain highly incurable. A need exists for new approaches to tumor therapy that can circumvent the blood brain barrier (BBB), target highly resistant tumors and cancer stem-like cells (CSCs) as well create an anti-cancer immunomodulatory environment. Successful treatments may also require a combinatory approach utilizing surgery, chemotherapy, radiation and novel ablation strategies that can both eliminate the bulk tumor and prevent any potential residual CSCs from propagating in the resected tissue. A number of thermal and non-thermal ablation methods have been developed and tested, which have gained much enthusiasm for the treatment of brain tumors. Here we review the most common primary brain tumors and the candidate ablation methods for targeting the tumor and its microenvironment.

Indoleamine 2,3-dioxygenase 1 is highly expressed in glioma stem cells

Recent research has revealed that glioblastoma (GBM) avoids the immune system via strong expression of indoleamine 2,3-dioxygenase 1 (IDO1). IDO1, an enzyme involved in tryptophan metabolism, is now proposed as a new target in GBM treatment, since several reports have demonstrated that IDO1 expression is related to GBM malignancy. On the other hand, it is well known that glioma stem cells (GSCs) are strongly related to the malignancy of GBM. However, there is as yet no report evaluating the relationship between GSCs and IDO1. We therefore examined the expression levels of IDO1 in GSCs in order to identify a new therapeutic target for GBM based on the immune systems of GSCs. In the present study, we employed human GBM cell lines (U-138MG, U-251MG) and patient-derived GSC model cell lines (0125-GSC, 0222-GSC). GSC model cell lines Rev-U-138MG and Rev-U-251MG were established by culturing U-138MG and U-251MG in serum-free media, while differentiated GBM model cell lines 0125-DGC and 0222-DGC were established by culturing 0125-GSC and 0222-GSC in serum-containing media. The expression levels of stem cell markers (Nanog, Nestin, Oct4 and Sox2) and IDO1 protein and mRNA were determined. Rev-U-138MG and Rev-U-251MG formed spheres and their expression levels of stem cell markers were increased as compared to U-138MG and U-251MG. On the other hand, 0125-DGC and 0222-DGC suffered breakdown of sphere formation, despite the original 0125-GSC and 0222-GSC forming spheres, and their expression levels of the markers were decreased. IDO1 expressions were strongly recognized in Rev-U-138MG, Rev-U-251MG, 0125-GSC and 0222-GSC as compared to U-138MG, U-251MG, 0125-DGC and 0222-DGC. These findings demonstrate that GSCs exhibit treatment resistance with immunosuppression via high expression levels of IDO1, and could represent a novel target for GBM treatment.

Characterization of Ablation Thresholds for 3D-Cultured Patient-Derived Glioma Stem Cells in Response to High-Frequency Irreversible Electroporation

High-frequency irreversible electroporation (H-FIRE) is a technique that uses pulsed electric fields that have been shown to ablate malignant cells. In order to evaluate the clinical potential of H-FIRE to treat glioblastoma (GBM), a primary brain tumor, we have studied the effects of high-frequency waveforms on therapy-resistant glioma stem-like cell (GSC) populations. We demonstrate that patient-derived GSCs are more susceptible to H-FIRE damage than primary normal astrocytes. This selectivity presents an opportunity for a degree of malignant cell targeting as bulk tumor cells and tumor stem cells are seen to exhibit similar lethal electric field thresholds, significantly lower than that of healthy astrocytes. However, neural stem cell (NSC) populations also exhibit a similar sensitivity to these pulses. This observation may suggest that different considerations be taken when applying these therapies in younger versus older patients, where the importance of preserving NSC populations may impose different restrictions on use. We also demonstrate variability in threshold among the three patient-derived GSC lines studied, suggesting the need for personalized cell-specific characterization in the development of potential clinical procedures. Future work may provide further useful insights regarding this patient-dependent variability observed that could inform targeted and personalized treatment.

In vitro effects of platelet-derived factors of brain glioma patients on C6 glioma cells

Platelets play an important part in the progression and pathological angiogenesis of brain glioma because of the different granules content and release of microvesicles that are the source of numerous mediators and bioactive substances, which probably provides a "strategy" for the tumour survival. The objective of study was exploring the effect of platelet-released secretion products of patients with brain glioma on the experimental model of tumour growth in vitro. For this purpose, the cells of glioma C6 were cultured for 72 hours under the addition of modified media containing platelet-released secretion products or conditioned media of peripheral blood cells of patients with glioma as well as persons of the comparison group without rough somatic pathology. In control glioma C6 cultures in standard conditions cell clusters were formed by the type of "spheroids", from which radial cell migration occurred, a tense cellular or reticular growth zone was formed, and tumour cells preserved their ability to mitotic division. Under the influence of platelet-released secretion products of patients with glioma, differently directed effects on cell mitotic activity and the number of cell clusters in glioma C6 cultures were detected depending on the degree of tumour malignancy: stimulating effect under the influence of platelet factors of patients with high-malignancy glioma (G4) and inhibitory effect – due to the influence of platelet factors of patients with differentiated glioma (G2). In contrast to the thrombocyte-released factors, the conditioned media of a common pool of peripheral blood cells of patients with G4 glioma suppressed the mitotic activity of tumour cells and did not affect the number of cell clusters. No changes in glioma C6 cultures were revealed after the influence of platelet-released secretion products of persons of the comparison group. The obtained data confirm the important role of platelets in the pathogenesis of brain glioma, pointing to the fundamental difference in the spectrum of biologically active molecules that are released by platelets of patients depending on the degree of tumour malignancy and are able to regulate the cell cycle and proliferative activity of the glioma tumour cells, which may have application as a diagnostic marker as well as predictive marker of response to antitumour therapy.

Cytometric analysis of cell suspension generated by cavitron ultrasonic surgical aspirator in pediatric brain tumors

PURPOSE

The aim of this study was to test the possibility of using specimens obtained by a cavitron ultrasonic surgical aspirator (CUSA) in flow and mass cytometry investigations of pediatric brain tumors.

METHODS

CUSA specimens obtained from 19 pediatric patients with brain tumors were investigated. Flow and mass cytometry methods were applied to analyze the composition of material collected using the CUSA. Cell suspensions were prepared from CUSA aspirates. Then sample viability was assessed by conventional flow cytometry and subsequently stained with a panel of 31 metal-labeled antibodies.

RESULTS

Viability assessment was performed using conventional flow cytometry. Viability of cells in the acquired samples was below 50% in 16 of 19 cases. A mass cytometry investigation and subsequent analysis enabled us to discriminate brain tumor cells from contaminating leukocytes, whose proportions varied across the specimens. The addition of the viability marker cisplatin directly into the mass cytometry panel gave the means to selecting viable cells only for subsequent analyses. The proportion of non-viable cells was higher among tumor cells compared leukocytes.

CONCLUSIONS

When the analysis of the tumor cell immunophenotype is performed with markers for determining viability, the expression of the investigated markers can be evaluated. Suitable markers can be selected by high-throughput methods, such as mass cytometry, and those that are diagnostically relevant can be investigated using flow cytometry, which is more flexible in terms of time.

Etoposide loaded layered double hydroxide nanoparticles reversing chemoresistance and eradicating human glioma stem cells in vitro and in vivo

Glioblastoma (GBM) is the most malignant and lethal glioma in human brain tumors and contains self-renewing, tumorigenic glioma stem cells (GSCs) that contribute to tumor initiation, therapeutic resistance and further recurrence. In this study, we combined in vitro cellular efficacy with in vivo antitumor performance to evaluate the outcome of an etoposide (VP16) loaded layered double hydroxide (LDH) nanocomposite (L-V) on human GSCs. The effects on GSC proliferation and apoptosis showed that loading with LDH could significantly sensitize GSCs to VP16 and enhance the GSC elimination. Further qPCR and western blot assays demonstrated that L-V could effectively attenuate GSC related pluripotency gene expression and reduce the cancer stemness. An in vivo GSC xenograft mice model showed that L-V can overcome drug resistance, eradicate GSCs, sharply decrease the stemness and reverse the epithelial-mesenchymal transition (EMT). RNA-seq analysis elucidated that L-V plays a vital role by down-regulating the PI3K/AKt/mTOR expression and activating the Wnt/GSK3β/β-catenin signaling pathway, hence leading to GSC stemness loss and greatly enhancing the GSC targeting effect. Taken together, this study demonstrated the outstanding performance of L-V reversing the drug resistance of GSCs, thus providing a novel strategy for clinical translation application of nanomedicine in malignant glioma chemotherapy.

Ultrastructural changes induced by Solanum incanum aqueous extract on HCT 116 colon cancer cells

Medicinal plants have recently gained increasing scientific interest as an important source of molecules with different therapeutic potentials. Accordingly, the present study was carried out to investigate ultrastructural changes induced by the aqueous extract of Solanum incanum (SI) fruit on human colorectal carcinoma cell line (HCT 116 cells). Examination of SI-treated HCT 116 cells with transmission electron microscopy (TEM) demonstrated numerous ultrastructural changes in the form of loss of the surface microvilli, mitochondrial damage and dilatation of cristae, and formation of autophagic vacuoles and increasing numbers of lipid droplets. Also, majority of the treated cells showed nuclear shrinkage with chromatin condensation and nucleolar changes. Moreover, some cells showed focal areas of cytoplasmic degeneration associating with formation of myelin figures and fatty globules. In conclusion, TEM was able to verify cytotoxicity of SI aqueous extract against HCT 116 colon cancer cells.

Temozolomide-induced increase of tumorigenicity can be diminished by targeting of mitochondria in in vitro models of patient individual glioblastoma

Glioblastoma multiforme (GBM) is a highly heterogeneous and aggressive brain tumor with a dismal prognosis. Development of resistance towards cytostatic drugs like the GBM standard drug temozolomide is a severe problem in GBM treatment. One potential source of GBM relapse could be so called cancer stem like cells (CSCs). These represent an undifferentiated subpopulation of cells with high potential for tumor initiation. Furthermore, it has been shown that differentiated GBM cells can regain CSC properties when exposed to continuous temozolomide treatment in vitro. In this study, treatment of several primary GBM cell lines with clinically relevant doses of temozolomide increased their tumorigenicity as determined by colony formation assays in soft agar. Increased tumorigenicity is a known property of CSCs. Hence, therapy options that specifically target CSCs are under investigation. CSCs appear to be particularly dependent on mitochondria biogenesis which may represent a useful target for CSC elimination. Toxicity towards mitochondria is a known side effect of several antibiotics. Thus, addition of antibiotics like doxycycline may represent a useful tool to inhibit CSCs in GBM. Here, we show that combining temozolomide treatment of primary GBM cells with doxycycline could counteract the increase of tumorigenicity induced by temozolomide treatment.

Aberrant expression of CD133 and CD82 in patients with pediatric acute lymphoblastic leukemia and the clinical significance

Cluster of differentiation (CD)133 is considered to be a marker of leukemia stem cells (LSCs), which are one of the primary causes of occurrence, drug resistance and relapse of acute lymphoblastic leukemia (ALL). CD82, an adhesion molecule, performs an important role in the interaction between LSCs and their niche. The purpose of the present study was to assess CD133 and CD82 expression in patients with pediatric ALL, and to evaluate the association with the clinical data. Using flow cytometric assessment and reverse transcription-polymerase chain reaction, CD133 and CD82 expression levels were measured in the bone marrow (BM) of 37 patients with newly diagnosed (ND) pediatric ALL [ALL-ND; 30 B-cell-ALL (B-ALL) and 7 T-cell-ALL (T-ALL)], in 22 patients with complete remission pediatric ALL (ALL-CR) and in 16 age-matched children without BM disease. BM plasma CD82 concentrations were measured by ELISA. The CD82 mRNA expression level in the patients with ALL-ND was significantly higher compared with that in the controls. CD82 mRNA expression levels in pediatric patients with B cell-ALL (B-ALL) were higher than those in ALL-CR patients and controls. For T-ALL, CD82 expression in ND patients was higher than in controls. CD133 mRNA expression levels in patients with pediatric B-ALL-ND were higher than that of controls and patients with ALL-CR. The frequency of CD34⁺ cells in pediatric ALL was significantly higher than that in controls. Frequencies of CD34⁺CD133⁺ or CD34⁺CD82⁺ cells in pediatric ALL were higher than those in controls. A positive association was observed between CD133 and CD82 mRNA expression in patients with B-ALL. A significant association was observed between CD133 mRNA expression and the hyperdiploid karyotype. Therefore, it was considered that CD133 and CD82 may serve an important role in the evolution of pediatric ALL. CD133 and CD82 should be considered as potential markers for the prognosis of patients with ALL.

Multivoxel magnetic resonance spectroscopy identifies enriched foci of cancer stem-like cells in high-grade gliomas

OBJECTIVE

This study investigated the correlation between choline/creatine (Cho/Cr) ratios determined by multivoxel proton magnetic resonance spectroscopy (¹H-MRS) and the distribution of cancer stem-like cells (CSLCs) in high-grade gliomas.

PATIENTS AND METHODS

Sixteen patients with high-grade gliomas were recruited and underwent ¹H-MRS examination before surgery to identify distinct tumor regions with variable Cho/Cr ratios. Using intraoperative neuronavigation, tumor tissues were accurately sampled from regions with high and low Cho/Cr ratios within each tumor. The distribution of CSLCs in samples from glioma tissue regions with different Cho/Cr ratios was quantified by neurosphere culture, immunohistochemistry, and Western blot.

RESULTS

The mean neurosphere formation rate in tissues with high Cho/Cr ratios was significantly increased compared with that in low Cho/Cr ratio tissues (13.94±5.94 per 100 cells vs 8.04±3.99 per 100 cells, P<0.001). Immunohistochemistry indicated that tissues with high Cho/Cr ratios had elevated expression of CD133, nestin, and CD15, relative to low Cho/Cr ratio tissue samples (23.6%±3.8% vs 18.3%±3.3%, 25.2%±4.5% vs 19.8%±2.8%, 24.5%±3.8% vs 17.8%±2.2%, respectively; all P<0.001). Western blot demonstrated that relative CD133 and nestin protein expression in high Cho/Cr ratio regions was significantly higher than that in low Cho/Cr ratio tissue samples (0.50±0.17 vs 0.30±0.08, 0.45±0.13 vs 0.27±0.07, respectively; both P<0.001). The protein expression levels of CD133 and nestin were highly correlated with Cho/Cr ratios (r=0.897 and r=0.861, respectively).

CONCLUSION

Cho/Cr ratios correlate with the distribution of CSLCs in high-grade gliomas, and this may assist in identifying foci enriched with CSLCs and thus improve the management of high-grade gliomas.

Intracranial undifferentiated malign neuroglial tumor in Smith-Lemli-Opitz syndrome: A theory of a possible predisposing factor for primary brain tumors via a case report

BACKGROUND

Smith-Lemli-Opitz Syndrome (SLOS) is a rare hereditary autosomal recessive disorder with broken cholesterol synthesis causing by 7-dehydrocholesterol reductase deficiency. Although the clinical features and pathogenesis is well-defined, it is unknown whether there is a relationship between SLOS and neoplastic processes, especially brain neoplasms.

PURPOSE

We aimed to attract the attentions to any possibility of relation between SLOS and intracranial tumor development via a pediatric case with both intracranial high-grade neuroglial tumor and SLOS, and thus to contribute an additional data to the literature on togetherness of these two clinical conditions.

METHOD

In our clinic, we experienced an interesting case of a 10-year-old child with both SLOS and huge brain tumor as rarely seen. Here, we reviewed the features and pathophysiology of SLOS and brain tumors via this case.

RESULTS

The patient was operated in our clinic, after, his brain tumor had been diagnosed, and his histopathology was resulted in undifferentiated malignant neuroglial WHO grade 4 tumor.

CONCLUSION

According to current literature, our case is the first report on coexisting of SLOS and intracranial undifferentiated malignant neuroglial tumor. Common pathways like impaired sonic hedgehog (Shh) signaling pathway may be considered for pathogenesis of a probable link between SLOS and brain tumors in further studies.

Tumorigenic lung tumorospheres exhibit stem-like features with significantly increased expression of CD133 and ABCG2

Accumulating evidence supports the existence of cancer stem cells (CSCs) in human tumors, and the successful certification of CSCs may lead to the identification of therapeutic targets, which are more effective for the treatment of cancer. The use of spherical cancer models has increased in popularity in cancer stem cell investigations. Tumorospheres, which are used as a model of CSCs and are established in serum‑free medium supplemented with growth factors under non‑adherent conditions, are one of the most commonly used cancer spherical models and are a valuable method for enriching the CSC fraction. To investigate whether this model is applicable in lung cancer (LC), the identification of lung CSCs and their capacities is essential. In the present study, lung CSCs were enriched by sphere-forming culturing and their stem‑like properties were assessed. The results indicated that the lung tumorospheres had enhanced proliferation, clonality, invasion and cisplatin‑resistance, and showed significantly increased expression levels of CD133 and breast cancer resistance protein (ABCG2). These results, together with findings previously reported in literature, indicated that the sphere‑forming culturing of LC cells induced the enrichment of CSCs and that the tumorospheres exhibited stem cell characteristics. In addition, the higher expression levels of CD133 and ABCG2 in the tumorospheres may provide a rationale for therapeutic targets for LC.

The cilia-regulated proteasome and its role in the development of ciliopathies and cancer

The primary cilium is an essential structure for the mediation of numerous signaling pathways involved in the coordination and regulation of cellular processes essential for the development and maintenance of health. Consequently, ciliary dysfunction results in severe human diseases called ciliopathies. Since many of the cilia-mediated signaling pathways are oncogenic pathways, cilia are linked to cancer. Recent studies demonstrate the existence of a cilia-regulated proteasome and that this proteasome is involved in cancer development via the progression of oncogenic, cilia-mediated signaling. This review article investigates the association between primary cilia and cancer with particular emphasis on the role of the cilia-regulated proteasome.

Cancer stem cells and personalized cancer nanomedicine

Despite the progress in cancer treatment over the past years advanced cancer is still an incurable disease. Special attention is pointed toward cancer stem cell (CSC)-targeted therapies, because this minor cell population is responsible for the treatment resistance, metastatic growth and tumor recurrence. The recently described CSC dynamic phenotype and interconversion model of cancer growth hamper even more the possible success of current cancer treatments in advanced cancer stages. Accordingly, CSCs can be generated through dedifferentiation processes from non-CSCs, in particular, when CSC populations are depleted after treatment. In this context, the use of targeted CSC nanomedicines should be considered as a promising tool to increase CSC sensitivity and efficacy of specific anti-CSC therapies.