Circadian Clock Gene bmal1 Acts as a Tumor Suppressor Gene in a Mice Model of Human Glioblastoma

Glioblastomas derived from malignant astrocytes are the most common primary tumors of the central nervous system in humans, exhibiting very bad prognosis. Treatment with surgery, radiotherapy, and chemotherapy (mainly using temozolomide), generates as much one-year survival. The circadian clock controls different aspects of tumor development, and its role in GBM is beginning to be explored. Here, the role of the canonic circadian clock gene bmal1 was studied in vivo in a nude mice model bearing human GBMs from LN229 cells xenografted orthotopically in the dorsal striatum. For that aim, a bmal1 knock-down was generated in LN229 cells by CRISPR/Cas9 gene editing tool, and tumor progression was followed in male mice by measuring survival, tumor growth, cell proliferation and prognosis with CD44 marker, as well as astrocyte activation in the tumor microenvironment with GFAP and nestin markers. Disruption of bmal1 in the tumor decreased survival, increased tumor growth and CD44 expression, worsened motor performance, as well as increased GFAP expression in astrocytes at tumor microenvironment. In addition, survival and tumor progression was not affected in mice bearing LN229 wild type GBM that underwent circadian disruption by constant light, as compared to mice synchronized to 12:12 light-dark cycles. These results consistently demonstrate in an in vivo orthotopic model of human GBM, that bmal1 has a key role as a tumor suppressor gene regulating GBM progression.

Antineoplastic effects of cassava-cyanide extract on human glioblastoma (LN229) cells

Several natural compounds reduce tumour cell growth and metastasis by inducing programmed cell death. Cassava (Manihot esculentaCrantz) contains cyanogenic glycosides such as, linamarin and lotaustralin, can be enzymatically cleaved by linamarase to release hydrogen cyanide (HCN), which can have therapeutic benefits against hypertension, asthma, and cancer. We have developed a technology for isolatingbio-active principles from cassava leaves.The present study is designed to analyzethe cytotoxic effect of cassava cyanideextract (CCE) against human glioblastoma cells (LN229). The treatment of CCE demonstrated a dose dependent toxicity on glioblastoma cells. At higher concentration tested, the CCE (400  μg/mL) was found to be cytotoxic, reducing the cell viability to 14.07 ± 2.15% by negatively influencing the mitochondrial activity, and lysosomal and cytoskeletal integrity. Coomassie's brilliant blue staining confirmed cells' morphological aberration after 24 h of treatment with CCE. Moreover, DCFH-DA assay and Griess reagent showed an increase in ROS but a decrease in RNS production at a concentration of CCE. Flow cytometry analysis revealed that CCE interfered with G0/G1, S, and G2/M stages of the cell cycle of glioblastoma, and Annexin/PI staining indicated a dose-dependent increase in cell death, confirming the toxic nature of CCE on LN229 cells. These findings suggest that cassava cyanide extract has potential as an antineoplastic agent against glioblastoma cells, which is an aggressive and difficult-to-treat type of brain cancer. However, it is important to note that the study was conducted in vitro, and further research is necessary to assess the safety and efficacy of CCE in vivo. Additionally, it is essential to establish the optimal dose and potential side effects before considering its use as a therapeutic agent.

Anticancer and antimicrobial activity of new copper (II) complexes

In this study, three new organic ligands N'-(benzylidene)-6-chloropyrazine-2-carbohydrazonamide (L₁), 6-chloro-N'-(4-nitrobenzylidene)picolinohydrazonamide(L₂), and N'-(benzylidene)-4-chloropicolinohydrazonamide (L₃) and three copper coordination compounds (Cu(L₁)Cl₂, Cu(L₂)Cl₂ and Cu(L₃)Cl₂) based on them were synthesized. All obtained compounds were characterized using appropriate analytical techniques: elemental analysis (EA), thermogravimetric analysis (TG-DTG), Fourier transform infrared spectroscopy (FTIR) and flame-atomic absorption spectrometry (F-AAS). These methods of physicochemical analyses helped to assume that the complexation in three cases proceeds in a bidentate manner. The X-ray investigation confirmed the synthesis pathway and molecular structures for L₁ and L₃ ligands. The antimicrobial activity of the obtained compounds was then comprehensively investigated, where Cu(L₃)Cl₂ showed the strongest antibacterial properties against all tested bacteria (Pseudomonas aeruginosa, Staphylococcus aureus, Escherichia coli). LN229 human glioma cells and BJ human normal fibroblasts cells were treated with tested compounds and their cytotoxicity was evaluated with MTT test. The effect of complexing on antitumor activity has been investigated. The ligand L₁ and its complex showed similar activity against normal cells while complexation increases toxicity against cancer cells in concentrations of 50 and 100 μM. For the one pair of ligand/complex compounds the apoptosis detection, cell cycle analysis and gene expression analysis (qRT-PCR) were performed. Cu(L₁)Cl₂ showed the stronger toxic effect in comparison with L₁ due to the population of early apoptotic cells which revealed metabolic activity in MTT assay.

CXCR4-STAT3 Axis Plays a Role in Tumor Cell Infiltration in an Orthotopic Mouse Glioblastoma Model

Glioblastoma multiforme (GBM) is a fatal malignant tumor that is characterized by diffusive growth of tumor cells into the surrounding brain parenchyma. However, the diffusive nature of GBM and its relationship with the tumor microenvironment (TME) is still unknown. Here, we investigated the interactions of GBM with the surrounding microenvironment in orthotopic xenograft animal models using two human glioma cell lines, U87 and LN229. The GBM cells in our model showed different features on the aspects of cell growth rate during their development, dispersive nature of glioma tumor cells along blood vessels, and invasion into the brain parenchyma. Our results indicated that these differences in the two models are in part due to differences in the expression of CXCR4 and STAT3, both of which play an important role in tumor progression. In addition, the GBM shows considerable accumulation of resident microglia and peripheral macrophages, but polarizes differently into tumor-supporting cells. These results suggest that the intrinsic factors of GBM and their interaction with the TME determine the diffusive nature and probably the responsiveness to non-cancer cells in the TME.

NMDA Receptor-Mediated Signaling Pathways Enhance Radiation Resistance, Survival and Migration in Glioblastoma Cells-A Potential Target for Adjuvant Radiotherapy

Glioblastoma is one of the most aggressive malignant brain tumors, with a survival time less than 15 months and characterized by a high radioresistance and the property of infiltrating the brain. Recent data indicate that the malignancy of glioblastomas depends on glutamatergic signaling via ionotropic glutamate receptors. In this study we revealed functional expression of Ca²⁺-permeable NMDARs in three glioblastoma cell lines. Therefore, we investigated the impact of this receptor on cell survival, migration and DNA double-strand break (DSB) repair in the presence of both, glutamate and NMDAR antagonists, and after clinically relevant doses of ionizing radiation. Our results indicate that treatment with NMDAR antagonists slowed the growth and migration of glutamate-releasing LN229 cells, suggesting that activation of NMDARs facilitate tumor expansion. Furthermore, we found that DSB-repair upon radiation was more effective in the presence of glutamate. In contrast, antagonizing the NMDAR or the Ca²⁺-dependent transcription factor CREB impaired DSB-repair similarly and resulted in a radiosensitizing effect in LN229 and U-87MG cells, indicating a common link between NMDAR signaling and CREB activity in glioblastoma. Since the FDA-approved NMDAR antagonists memantine and ifenprodil showed differential radiosensitizing effects, these compounds may constitute novel optimizations for therapeutic interventions in glioblastoma.

NMDA Receptor Signaling Mediates cFos Expression via Top2β-Induced DSBs in Glioblastoma Cells

The activation of Ca²⁺-permeable N-methyl-D-aspartic acid (NMDA) receptor channels (NMDARs) is crucial for the development and survival of neurons, but many cancers use NMDAR-mediated signaling as well, enhancing the growth and invasiveness of tumors. Thus, NMDAR-dependent pathways emerge as a promising target in cancer therapy. Here, we use the LN229 and U-87MG glioblastoma multiforme (GBM) cells and immunofluorescence staining of 53BP1 to analyze NMDAR-induced DNA double-strand breaks (DSBs), which represent an important step in the NMDAR signaling pathway in neurons by facilitating the expression of early response genes. Our results show that NMDAR activation leads to the induction of DSBs in a subpopulation of glioma cells. In a further analogy to neurons, our results demonstrate that the induction of DSBs in LN229 cells is dependent on the activity of topoisomerase IIβ (Top2β). Western blot analysis revealed that the inhibition of NMDARs, cAMP-responsive element binding transcription factor (CREB) and Top2β decreased the expression of the proto-oncogene cFos. Knockdown of Top2β with siRNAs resulted in a downregulation of cFos and increased the radiosensitivity of LN229 cells in clonogenic survival. We also observed impaired cFos expression upon NMDAR and Top2β inhibition in a primary GBM cell line, suggesting that NMDAR signaling may be widely used by GBMs, demonstrating the potential of targeting NMDAR signaling proteins for GBM therapy.

Phenformin and metformin inhibit growth and migration of LN229 glioma cells in vitro and in vivo

Background

Malignant glioma is refractory to conventional treatment, highlighting a need to develop novel efficacious therapies. Biguanides, a class of oral antidiabetic drug, have been thought to inhibit proliferation and metastasis in a variety of cancers.

Purpose

The objective of this study was to investigate the affections of biguanides, phenformin (Phen) and metformin (Met), on growth and migration of glioma cells LN229 in vitro and in vivo.

Methods

Glioma cells LN229 were treated with Phen or Met, then cell proliferation and death were evaluated by MTT assay and PI stain, and cell cycle were evaluated using flow cytometric analysis, meantime wound healing assay and transwell migration assay were performed to detect cell migration ability. In addition, LN229 were injected in thigh of nude mice, and the mice were treated with Phen or Met to detect the effect of Phen and Met in vivo.

Results

Phen and Met could significantly inhibit cell growth through inhibiting cell proliferation, promoting cell death and disturbing cell cycle, and these drugs also could inhibit cell colony formation in glioma cells LN229 in vitro. Meanwhile, both Phen and Met could significantly inhibit cell migration of LN229 in vitro, through effecting the expression of E-cadherin and Vimentin. In addition, both Phen and Met inhibited the growth and migration of LN229 in a tumor xenograft model. Furthermore, Phen and Met were associated with the increased level of ROS of cell mitochondrial, and ROS inhibitor NAC could significantly rescue the cell death induced by Phen and Met.

Conclusion

Phen and Met displayed powerful antitumor effects of LN229, and our findings powerfully suggest the possibility of Phen and Met being used as an adjuvant agent in the treatment of glioma patients.