Rodent Glioma Models: Intracranial Stereotactic Allografts and Xenografts

Aloperine targets lysosomes to inhibit late autophagy and induces cell death through apoptosis and paraptosis in glioblastoma

Glioblastoma (GBM) is an aggressive intracranial tumour, and current chemotherapy regimens have limited efficacy. Aloperine (ALO), a natural alkaline compound, has shown potential as an antitumor agent. However, the effect of ALO against GBM remains unclear. This study aimed to investigate the function of ALO in treating GBM. U87, A172, and GL261 cell lines were used for in vitro experiments, and GL261 was also used to establish in vivo models. The results showed that ALO inhibited the proliferation of GBM cells by cell cycle arrest and apoptosis. Furthermore, autophagy was found to play a critical role, suggested by observation of autophagosomes under the transmission electron microscopy. It was discovered for the first time that ALO targeted lysosomes directly in glioma cells, tested by fluo-rescence-labelled ALO and organelle-localizing probes. In addition, ALO inhibited late autophagy and induced paraptosis in GBM, verified by classical gene expression changes in qPCR and western blotting. Also, ALO inhibited tumour growth and acted synergistically with temozolomide in intracranial glioma mice models in vivo. Our findings suggest that ALO targets lysosomes to inhibit late autophagy in GBM, inducing cell cycle arrest, paraptosis, and apoptosis. ALO may therefore be a promising therapeutic agent for the treatment of GBM.

Local administration of shikonin improved the overall survival in orthotopic murine glioblastoma models with temozolomide resistance

BACKGROUND

Glioblastoma is a type of intracranial malignancy. Shikonin, a Chinese traditional medicine, has been shown to have anti-tumor efficacy toward human glioblastoma cells in vitro. However, shikonin cannot easily cross the blood-brain barrier. To address this issue, we evaluated the anti-tumor effects of direct intracranial infusion of shikonin in in vivo orthotopic syngeneic murine glioblastoma models using C57BL/6 mice.

MATERIALS AND METHODS

The cytotoxic effects of shikonin against murine glioblastoma cells, SB28 and CT-2A, were reported resistance to temozolomide, were evaluated using an allophycocyanin-conjugated annexin V and propidium iodide assay with flow cytometry. Impedance-based real-time cell analysis (RTCA) was used to analyze the inhibitory effects of shikonin on growth and proliferation. To evaluate the anti-tumor activity of shikonin in vivo, we used orthotopic syngeneic murine glioblastoma models with SB28 and CT-2A cells.

RESULTS

In flow cytometry-based cytotoxic assays, shikonin induced apoptosis. RTCA indicated that shikonin decreased the cell index of murine glioblastoma cells, SB28 and CT-2A, in a dose-dependent manner (p < 0.0001 for both cell lines), while temozolomide did not (p = 0.91 and 0.82, respectively). In murine glioblastoma models, SB28 and CT-2A, direct intracranial infusion of shikonin, as a local chemotherapy, improved the overall survival of mice in a dose-dependent manner compared with control groups (p < 0.0001 and p = 0.02, respectively). While temozolomide did not (p = 0.48 and 0.52, respectively).

CONCLUSIONS

The direct intracranial infusion of shikonin has potential as a local therapy for patients with glioblastoma.

The first endovascular rat glioma model for pre-clinical evaluation of intra-arterial therapeutics

BACKGROUND

Several translational animal models have been described assessing intra-arterial (IA) treatments for malignant gliomas. We describe the first endovascular animal model that allows testing of IA drug delivery as a first-line treatment, which is difficult to do in actual patients. We report a unique protocol for vascular access and IA delivery in the rat model that, unlike prior reports, does not require direct puncture and opening of proximal cerebrovasculature which carries risk of ischemia in the animal brain post-delivery.

METHODS

Wistar rats underwent left femoral artery catherization with a Balt Magic 1.2F catheter or Marathon Flow directed 1.5F Microcatheter with an Asahi Chikai 0.008 micro-guidewire which was navigated to the left internal carotid artery under x-ray. 25% mannitol was administered to test blood brain barrier breakdown (BBBB). Additional rats were implanted with C6 glioma cells in the left frontal lobe. C6 Glioma-Implanted Rats (C6GRs) were monitored for overall survival and tumor growth. Tumor volumes from MRI images were calculated utilizing 3D slicer. Additional rats underwent femoral artery catheterization with Bevacizumab, carboplatin, or irinotecan injected into the left internal carotid artery to test feasibility and safety.

RESULTS

A successful endovascular access and BBBB protocol was established. BBBB was confirmed with positive Evans blue staining. 10 rats were successfully implanted with C6 gliomas with confirmed growths on MRI. Overall survival was 19.75 ± 2.21 days. 5 rats were utilized for the development of our femoral catheterization protocol and BBBB testing. With regards to IA chemotherapy dosage testing, control rats tolerated targeted 10 mg/kg of bevascizumab, 2.4 mg/kg of carboplatin, and 15 mg/kg of irinotecan IA ICA injections without any complications.

CONCLUSIONS

We present the first endovascular IA rat glioma model that allows selective catheterization of the intracranial vasculature and assessment of IA therapies for gliomas without need for access and sacrifice of proximal cerebrovasculature.

Label-free identification of human glioma xenograft of mouse brain with quantitative ultraviolet photoacoustic histology imaging

The ability to unveil molecular specificities of endogenous nonfluorescent chromophores of ultraviolet photoacoustic imaging technology enables label-free histology imaging of tissue specimens. In this work, we exploit ultraviolet photoacoustic microscopy for identifying human glioma xenograft of mouse brain ex vivo. Intrinsically excellent imaging contrast of cell nucleus at ultraviolet photoacoustic illumination along with good spatial resolution allows for discerning the brain glioma of freshly-harvested thick brain slices, which circumvents laborious time-consuming preparations of the tissue specimens including micrometer-thick slicing and H&E staining that are prerequisites in standard histology analysis. The identification of tumor margins and quantitative analysis of tumor areas is implemented, representing good agreement with the standard H&E-stained observations. Quantitative ultraviolet photoacoustic microscopy can access fast pathological assessment to the brain tissues, and thus potentially facilitates intraoperative brain tumor resection to precisely remove all cancerous cells and preserve healthy tissue for maintaining its essential function.

Changes in Spectral Fluorescence Properties of a Near-Infrared Photosensitizer in a Nanoform as a Coating of an Optical Fiber Neuroport

In this work, we tested a new approach to assess the presence of inflammatory process in the implant area using spectral methods and the technique of fiber fluorescence analysis of photosensitizers in nanoform. First of all, the spectral characteristics of the photosensitizer when interacting with the porous surface of the implant, based on hydroxyapatite under in vitro and in vivo conditions, were determined. Thus, it was shown that spectral characteristics of photosensitizers can be used for judgement on the process of inflammation in the implant area and thus on the local presence of the immunocompetent cells. The analysis was performed at a sufficient depth in the biotissue by using the near-infrared spectral region, as well as two different methods: fiber-based laser spectroscopy and fiber-optic neuroscopy, which served to monitor the process and regular fluorescence diagnosis of the studied area. Fluorescence spectroscopic analysis was performed on experimental animals in vivo, i.e., under conditions of active immune system intervention, as well as on cell cultures in vitro in order to judge the role of the immune system in the interaction with the implant in comparison. Thus, the aim of the study was to determine the relationship between the fluorescence signal of nanophotosensitizers in the near infrared spectral region and its parameters with the level of inflammation and the type of surface with which the photosensitizer interacts in the implant area. Thus, fiber-optic control opens up new approaches for further diagnosis and therapy in the implant area, making immune cells a prime target for advanced therapies.

Near-Infrared Monoamine Oxidase Inhibitor Biodistribution in a Glioma Mouse Model

PURPOSE

The biodistribution imaging kinetics of near-infrared monoamine oxidase inhibitor (NMI) are reported here.

METHODS

NMI was administered intravenously or orally to mice and detected by NIR fluorescence optical imaging within minutes and the longitudinal signal distribution was measured for up to 1 week after a single dose.

RESULTS

NMI rapidly reached 3.7-fold higher ventral and 3.2-fold higher brain region fluorescent signal intensity compared to oral route at 24 h. Similar patterns of NMI biodistribution were found in mice with or without intracranial implanted GL26 brain tumors. NMI was highly associated with tumors in contrast to adjacent non-tumor brain, confirming diagnostic utility. NMI 5 mg/kg imaging signal in brain at 48 h was optimal (tumor/non-tumor ratio > 3.5) with minimum off-target distribution. Intravenous NMI imaging signal peaked between 24 h and 48 h for lung, liver, kidney, blood, brain, and most other tissues. Clearance (signal weaker, but still present) from most tissues occurred by day 7. Intravenous low dose (0.5 mg/kg) minimally labeled tumor and other tissues, 5 mg/kg showed optimal imaging signal in glioma at a dose we previously reported as efficacious, and 50 mg/kg was tolerable but saturated the tissue signals beyond tumor specificity. Gel electrophoresis showed two major bands present in brain tumor and tissue protein lysates.

CONCLUSIONS

Intravenous 5 mg/kg was optimal dose to target brain tumor and identified off-target organs of concern: lungs, liver, and kidneys. These results demonstrate the biodistribution and optimal dose range of NMI for treatment and diagnostic monitoring of glioma.

Hypoxia-induced EPHB2 promotes invasive potential of glioblastoma

EphB2, a receptor tyrosine kinase for ephrin ligands, is overexpressed in various cancers and plays an important role in tumor progression. EPHB2 promotes endothelial-mesenchymal transition (EMT) and elicits associated pathologic characteristics of glioblastoma multiforme (GBM) such as invasion and migration. However, the mechanisms of the EPHB2 regulatory network in glioma remain enigmatic. Here, we report that EPHB2 is epigenetically overexpressed in hypoxia, a condition highly prevalent in malignancy. Furthermore, HIF-2α is required for EPHB2 stabilization by hypoxia. Lastly, we discovered that the overexpression of EPHB2 promotes GBM invasion by the phosphorylation of paxillin in hypoxia. These findings establish the HIF-2α-EPHB2-paxillin axis as a regulatory mechanism of epithelial-mesenchymal transition.

Preclinical characterization of signal transducer and activator of transcription 3 small molecule inhibitors for primary and metastatic brain cancer therapy

Signal transducer and activator of transcription 3 (STAT3) has been implicated as a hub for multiple oncogenic pathways. The constitutive activation of STAT3 is present in several cancers, including gliomas (GBMs), and is associated with poor therapeutic responses. Phosphorylation of STAT3 triggers its dimerization and nuclear transport, where it promotes the transcription of genes that stimulate tumor growth. In light of this role, inhibitors of the STAT3 pathway are attractive therapeutic targets for cancer. To this end, we evaluated the STAT3-inhibitory activities of three compounds (CPA-7 [trichloronitritodiammineplatinum(IV)], WP1066 [(S,E)-3-(6-bromopyridin-2-yl)-2-cyano-N-(1-phenylethyl)acrylamide, C17H14BrN3O], and ML116 [4-benzyl-1-{thieno[2,3-d]pyrimidin-4-yl}piperidine, C18H19N3S]) in cultured rodent and human glioma cells, including GBM cancer stem cells. Our results demonstrate a potent induction of growth arrest in GBM cells after drug treatment with a concomitant induction of cell death. Although these compounds were effective at inhibiting STAT3 phosphorylation, they also displayed variable dose-dependent inhibition of STAT1, STAT5, and nuclear factor κ light-chain enhancer of activated B cells. The therapeutic efficacy of these compounds was further evaluated in peripheral and intracranial mouse tumor models. Whereas CPA-7 elicited regression of peripheral tumors, both melanoma and GBM, its efficacy was not evident when the tumors were implanted within the brain. Our data suggest poor permeability of this compound to tumors located within the central nervous system. WP1066 and ML116 exhibited poor in vivo efficacy. In summary, CPA-7 constitutes a powerful anticancer agent in models of peripheral solid cancers. Our data strongly support further development of CPA-7-derived compounds with increased permeability to enhance their efficacy in primary and metastatic brain tumors.