Sunitinib impedes brain tumor progression and reduces tumor-induced neurodegeneration in the microenvironment

Intranasal delivery of sunitinib: A new therapeutic approach for targeting angiogenesis of glioblastoma

Glioblastoma multiforme (GBM) is one of the most vascular among solid tumors, and despite the use of multimodal therapies, the survival of these patients is poor. In order to target angiogenesis in GBM as a promising strategy, an antiangiogenic drug is required. This study was designed to evaluate the effects of sunitinib, a multityrosine kinase inhibitor with tumor proliferation and angiogenesis inhibitory properties, on GBM-bearing rats. Given the ineffective drug delivery to the brain due to the presence of the blood-brain barrier (BBB), intra-nasal (IN) drug delivery has recently been considered as a non-invasive method to bypass BBB. Therefore, in the current study, IN was used as an ideal method for the delivery of sunitinib to the brain, and the effects of this method were also compared to the OR administration of the sunitinib. GBM was induced in the brain of male Wistar rats, and they were randomly divided into 4 groups; IN-STB (sunitinib intranasal delivery), IN-sham (placebo intranasal delivery), OR-STB (sunitinib oral delivery) and OR-sham (placebo oral delivery). After the end of the treatment period, an MRI of animals' brains showed a reduction in tumor growth in the treatment groups. Immunohistochemistry revealed that sunitinib inhibits angiogenesis in GBM in both OR and IN delivery methods. Analysis of liver tissue and enzymes showed that IN delivery of sunitinib had less hepatotoxicity than the OR method. Overall, it was found that IN sunitinib delivery could be used as a potential non-hepatotoxic alternative for the treatment of GBM.

Clinical drug response prediction from preclinical cancer cell lines by logistic matrix factorization approach

Predicting tumor drug response using cancer cell line drug response values for a large number of anti-cancer drugs is a significant challenge in personalized medicine. Predicting patient response to drugs from data obtained from preclinical models is made easier by the availability of different knowledge on cell lines and drugs. This paper proposes the TCLMF method, a predictive model for predicting drug response in tumor samples that was trained on preclinical samples and is based on the logistic matrix factorization approach. The TCLMF model is designed based on gene expression profiles, tissue type information, the chemical structure of drugs and drug sensitivity (IC 50) data from cancer cell lines. We use preclinical data from the Genomics of Drug Sensitivity in Cancer dataset (GDSC) to train the proposed drug response model, which we then use to predict drug sensitivity of samples from the Cancer Genome Atlas (TCGA) dataset. The TCLMF approach focuses on identifying successful features of cell lines and drugs in order to calculate the probability of the tumor samples being sensitive to drugs. The closest cell line neighbours for each tumor sample are calculated using a description of similarity between tumor samples and cell lines in this study. The drug response for a new tumor is then calculated by averaging the low-rank features obtained from its neighboring cell lines. We compare the results of the TCLMF model with the results of the previously proposed methods using two databases and two approaches to test the model's performance. In the first approach, 12 drugs with enough known clinical drug response, considered in previous methods, are studied. For 7 drugs out of 12, the TCLMF can significantly distinguish between patients that are resistance to these drugs and the patients that are sensitive to them. These approaches are converted to classification models using a threshold in the second approach, and the results are compared. The results demonstrate that the TCLMF method provides accurate predictions across the results of the other algorithms. Finally, we accurately classify tumor tissue type using the latent vectors obtained from TCLMF's logistic matrix factorization process. These findings demonstrate that the TCLMF approach produces effective latent vectors for tumor samples. The source code of the TCLMF method is available in https://github.com/emdadi/TCLMF.

Development of Novel VEGFR2 Inhibitors Originating from Natural Product Analogues with Antiangiogenic Impact

A novel natural small molecule, voacangine (Voa), has been discovered as a potent antiangiogenic compound. Notably, Voa directly binds the kinase domain of the vascular endothelial growth factor receptor 2 (VEGFR2) and thereby inhibits downstream signaling. Herein, we developed synthetic small molecules based on the unique chemical structure of Voa that directly and specifically target and modulate the kinase activity of VEGFR2. Among these Voa structure analogues, Voa analogue 19 (V19) exhibited increased antiangiogenic potency against VEGF-induced VEGFR2 phosphorylation without cytotoxic effects. Moreover, treatment with V19 resulted in significant tumor cell death in a mouse xenograft model. In conclusion, this new VEGFR2 modulator, inspired from the rigid scaffold of a natural compound, Voa, is presented as a potent candidate in the development of new antiangiogenic agents.

A novel method of screening combinations of angiostatics identifies bevacizumab and temsirolimus as synergistic inhibitors of glioma-induced angiogenesis

Tumor angiogenesis is critical for the growth and progression of cancer. As such, angiostasis is a treatment modality for cancer with potential utility for multiple types of cancer and fewer side effects. However, clinical success of angiostatic monotherapies has been moderate, at best, causing angiostatic treatments to lose their early luster. Previous studies demonstrated compensatory mechanisms that drive tumor vascularization despite the use of angiostatic monotherapies, as well as the potential for combination angiostatic therapies to overcome these compensatory mechanisms. We screened clinically approved angiostatics to identify specific combinations that confer potent inhibition of tumor-induced angiogenesis. We used a novel modification of the ex ovo chick chorioallantoic membrane (CAM) model that combined confocal and automated analyses to quantify tumor angiogenesis induced by glioblastoma tumor onplants. This model is advantageous due to its low cost and moderate throughput capabilities, while maintaining complex in vivo cellular interactions that are difficult to replicate in vitro. After screening multiple combinations, we determined that glioblastoma-induced angiogenesis was significantly reduced using a combination of bevacizumab (Avastin®) and temsirolimus (Torisel®) at doses below those where neither monotherapy demonstrated activity. These preliminary results were verified extensively, with this combination therapy effective even at concentrations further reduced 10-fold with a CI value of 2.42E-5, demonstrating high levels of synergy. Thus, combining bevacizumab and temsirolimus has great potential to increase the efficacy of angiostatic therapy and lower required dosing for improved clinical success and reduced side effects in glioblastoma patients.

Functional inhibition of cancer stemness-related protein DPP4 rescues tyrosine kinase inhibitor resistance in renal cell carcinoma

Tyrosine kinase inhibitors (TKIs) are used as targeted drugs for advanced renal cell carcinoma (RCC), although most cases eventually progress by acquiring resistance. Cancer stemness plays critical roles in tumor aggressiveness and therapeutic resistance, and dipeptidyl peptidase IV (DPP4) has been recently identified as a cancer stemness-related protein. A question arises whether DPP4 contributes to TKI efficacy in RCC. We established patient-derived RCC spheroids and showed that DPP4 expression is associated with stemness-related gene expression. TKI sunitinib resistance was rescued by DPP4 inhibition using sitagliptin or specific siRNAs in RCC cells and tumors. DPP4 expression can be inducible by retinoic acid and repressed by ALDH1A inhibition. Among type 2 diabetes patients with clinical RCC tumors, higher TKI efficacy is observed in those bearing DPP4^high tumors treated with DPP4 inhibitors. This study provides new insights into TKI resistance and drug repositioning of DPP4 inhibitor as a promising strategy for advanced RCC.

Vascular normalization in immunotherapy: A promising mechanisms combined with radiotherapy

Leakage and compression of blood vessels may result in deprivation of blood flow to a large number of tumor tissues, which can lead to tumor hypoxia. Hypoxia induces an increase in the expression of hypoxia-inducible factor 1 in tumor cells, which induces angiogenesis in tumors through the high expression of vascular endothelial growth factor, thereby forming a positive feedback vicious circle. Improving hypoxia by normalizing blood vessels and improving radiosensitivity by immunotherapy has emerged as a new application of combined immunotherapy and radiotherapy. Interferon γ produced by CD4 + /CD8 + T cells, induced by immune checkpoint inhibitors, plays an important role in the normalization of blood vessels; tumor-associated eosinophils also play a role in the process of immunotherapy-induced blood vessel normalization. In addition, the reduction in regulatory T cells induced by immune checkpoint inhibitors can increase eosinophil levels, which promotes the further development of vascular normalization mechanisms. This review focuses on the mechanism of immunotherapy to normalize blood vessels, and proposes a good prospect for improving hypoxia. Due to the narrow vascular normalization window of anti-angiogenesis therapy, discovery of the vascular normalization effect of immunotherapy provides a new idea for the combined application of immunotherapy and radiotherapy. The enlarged vascular normalization window and improved hypoxia provide a good opportunity for the subsequent implementation of radiotherapy. The above sorting and analysis may pave the way for a promising strategy for cancer treatment via combined immunotherapy and radiotherapy.

Guanabenz Sensitizes Glioblastoma Cells to Sunitinib by Inhibiting GADD34-Mediated Autophagic Signaling

Limited therapeutic efficacy of temozolomide (TMZ) against glioblastomas highlights the importance of exploring new drugs for clinical therapy. Sunitinib, a multitargeted receptor tyrosine kinase inhibitor, is currently being tested as therapy for glioblastomas. Unfortunately, sunitinib still has insufficient activity to cure glioblastomas. Our aim was to determine the molecular mechanisms counteracting sunitinib drug sensitivity and find potential adjuvant drugs for glioblastoma therapy. Through in vitro experiments, transcriptome screening by RNA sequencing, and in silico analyses, we found that sunitinib induced glioma apoptotic death, and downregulated genes were enriched in oncogenic genes of glioblastoma. Meanwhile, sunitinib-upregulated genes were highly associated with the protective autophagy process. Blockade of autophagy significantly enhanced sunitinib's cytotoxicity. Growth arrest and DNA damage-inducible protein (GADD) 34 was identified as a candidate involved in sunitinib-promoted autophagy through activating p38-mitogen-activated protein kinase (MAPK) signaling. Higher GADD34 levels predicted poor survival of glioblastoma patients and induced autophagy formation in desensitizing sunitinib cytotoxicity. Guanabenz, an alpha2-selective adrenergic agonist and GADD34 functional inhibitor, was identified to enhance the efficacy of sunitinib by targeting GADD34-induced protective autophagy in glioblastoma cells, TMZ-resistant cells, hypoxic cultured cells, sphere-forming cells, and colony formation abilities. A better combined treatment effect with sunitinib and guanabenz was also observed by using xenograft mice. Taken together, the sunitinib therapy combined with guanabenz in the inhibition of GADD34-enhanced protective autophagy may provide a new therapeutic strategy for glioblastoma.

Blood-Brain Barrier Disruption: A Common Driver of Central Nervous System Diseases

The brain is endowed with a unique cellular composition and organization, embedded within a vascular network and isolated from the circulating blood by a specialized frontier, the so-called blood-brain barrier (BBB), which is necessary for its proper function. Recent reports have shown that increments in the permeability of the blood vessels facilitates the entry of toxic components and immune cells to the brain parenchyma and alters the phenotype of the supporting astrocytes. All of these might contribute to the progression of different pathologies such as brain cancers or neurodegenerative diseases. Although it is well known that BBB breakdown occurs due to pericyte malfunctioning or to the lack of stability of the blood vessels, its participation in the diverse neural diseases needs further elucidation. This review summarizes what it is known about BBB structure and function and how its instability might trigger or promote neuronal degeneration and glioma progression, with a special focus on the role of pericytes as key modulators of the vasculature. Moreover, we will discuss some recent reports that highlights the participation of the BBB alterations in glioma growth. This pan-disease analysis might shed some light into these otherwise untreatable diseases and help to design better therapeutic approaches.

Applied Precision Cancer Medicine in Neuro-Oncology

Brain tumours that are refractory to treatment have a poor prognosis and constitute a major challenge in offering effective treatment strategies. By targeting molecular alterations, precision cancer medicine may be a viable option for the treatment of brain tumours. In this retrospective analysis of our PCM platform, we describe the molecular profiling of primary brain tumours from 50 patients. Tumour samples of the patients were examined by a 161-gene next-generation sequencing panel, immunohistochemistry, and fluorescence in situ hybridization (FISH). We identified 103 molecular aberrations in 36 (72%) of the 50 patients. The predominant mutations were TP53 (14.6%), IDH1 (9.7%) and PIK3CA (6.8%). No mutations were detected in 14 (28%) of the 50 patients. IHC demonstrated frequent overexpression of EGFR and mTOR, in 38 (76%) and 35 (70%) patients, respectively. Overexpression of PDGFRa and PDGFRb were less common and detected in 16 and four patients, respectively. For 35 patients a targeted therapy was recommended. In our database, the majority of patients displayed mutations, against which targeted therapy could be offered. Based on our observations, PCM may be a feasible novel treatment approach in neuro-oncology.

The Brain Penetrating and Dual TORC1/TORC2 Inhibitor, RES529, Elicits Anti-Glioma Activity and Enhances the Therapeutic Effects of Anti-Angiogenetic Compounds in Preclinical Murine Models

Background. Glioblastoma multiforme (GBM) is a devastating disease showing a very poor prognosis. New therapeutic approaches are needed to improve survival and quality of life. GBM is a highly vascularized tumor and as such, chemotherapy and anti-angiogenic drugs have been combined for treatment. However, as treatment-induced resistance often develops, our goal was to identify and treat pathways involved in resistance to treatment to optimize the treatment strategies. Anti-angiogenetic compounds tested in preclinical and clinical settings demonstrated recurrence associated to secondary activation of the phosphatidylinositol 3-kinase (PI3K)/AKT/mTOR pathway. Aims. Here, we determined the sensitizing effects of the small molecule and oral available dual TORC1/TORC2 dissociative inhibitor, RES529, alone or in combination with the anti-VEGF blocking antibody, bevacizumab, or the tyrosine kinase inhibitor, sunitinib, in human GBM models. Results. We observed that RES529 effectively inhibited dose-dependently the growth of GBM cells in vitro counteracting the insurgence of recurrence after bevacizumab or sunitinib administration in vivo. Combination strategies were associated with reduced tumor progression as indicated by the analysis of Time to Tumor Progression (TTP) and disease-free survival (DSF) as well as increased overall survival (OS) of tumor bearing mice. RES529 was able to reduce the in vitro migration of tumor cells and tubule formation from both brain-derived endothelial cells (angiogenesis) and tumor cells (vasculogenic mimicry). Conclusions. In summary, RES529, the first dual TORC1/TORC2 dissociative inhibitor, lacking affinity for ABCB1/ABCG2 and having good brain penetration, was active in GBM preclinical/murine models giving credence to its use in clinical trial for patients with GBM treated in association with anti-angiogenetic compounds.

Overexpression of FZD1 is Associated with a Good Prognosis and Resistance of Sunitinib in Clear Cell Renal Cell Carcinoma

Frizzled class receptor 1 (FZD1), a receptor for Wnt signaling pathway. Overexpression of FZD1 has been detected in many cancer tissues and cells resulting in tumor development and drug resistance. However, its expression status and prognostic merit in renal cancer still remains unclear. We screened the FZD1 mRNA in clear cell renal cell carcinoma (ccRCC) and papillary renal cell carcinoma (pRCC) from TCGA database and Oncomine database. We then detected FZD1 mRNA expression in sunitinib-resistant cells and the corresponding parental cells by qRT-PCR. FZD1 level was significantly upregulated in renal cancer tissues, renal cancer cell lines and their corresponding sunitinib-resistant cells. FZD1 level was also associated with the clinicopathological characteristics of ccRCC patients that could discriminate metastasis, pathological stage, recurrence and prognosis in ccRCC patients. The Kaplan-Meier survival curve and the log-rank test revealed FZD1 was higher in lower clinical stage and grade that correlated with better overall survival (OS) and disease-free survival (DFS) in total and subgroups of ccRCC patients. Both univariate and multivariate cox regression analysis indicated that high FZD1 level was an independent predictor of good prognosis for OS (HR 0.569, P=0.001) and DFS (HR 0.559, P=0.036) in ccRCC patients. Using cBioportal program, less than 1% mutation in the patients with renal cancer was observed, the alterations in FZD1 were correlated with better OS (P=0.0404) in ccRCC patients. Finally, the result of KEGG pathway analysis predicted seven potential pathways that FZD1 and its related genes got involved in ccRCC, including Hippo signaling pathway. This indicated potential therapeutic targets of ccRCC. In conclusion, our results suggested that expression status of FZD1 had a diagnostic value and prognostic value in ccRCC patients, it also may serve as a potential drug target to relieve sunitinib resistance in renal cancer patients.

Cabazitaxel operates anti-metastatic and cytotoxic via apoptosis induction and stalls brain tumor angiogenesis

Taxanes target microtubules and are clinically established chemotherapeutic agents with proven efficacy in human cancers. Cabazitaxel (XRP-6258, Jevtana®) is a second generation semisynthetic taxane with high chemotherapeutic potential in prostate cancer. There, cabazitaxel can overcome docetaxel-resistant prostate cancer. Here, we tested the effects of cabazitaxel on glioma cells, and non-transformed cells such as neurons and astrocytes. Cabazitaxel operates highly toxic in various human glioma cells at nanomolar concentrations. In contrast, primary astrocytes and neurons are not affected by this agent. Cabazitaxel disrupts cytoskeletal F-actin fibers and induces apoptotic cell death in gliomas. Moreover, cabazitaxel displayed highest efficacy in inhibiting glioma cell migration and invasion. Here we demonstrate that cabazitaxel inhibited tumor migration already at 1 nM. We also tested cabazitaxel in the ex vivo VOGiM assay. Cabazitaxel stalled glioma growth and at the same time inhibited tumor-induced angiogenesis. In summary, we found that cabazitaxel operates as an apoptosis-inducing gliomatoxic agent with strongest effects on migration and invasive growth. Thus, our report uncovered cabazitaxel actions on gliomas and on the brain tumor microenvironment. These data reveal novel aspects for adjuvant approaches when applied to brain tumor patients.

Targeting tumour microenvironment by tyrosine kinase inhibitor

Tumour microenvironment (TME) is a key determinant of tumour growth and metastasis. TME could be very different for each type and location of tumour and TME may change constantly during tumour growth. Multiple counterparts in surrounding microenvironment including mesenchymal-, hematopoietic-originated cells as well as non-cellular components affect TME. Thus, therapeutics that can disrupt the tumour-favouring microenvironment should be further explored for cancer therapy. Previous efforts in unravelling the dysregulated mechanisms of TME components has identified numerous protein tyrosine kinases, while its corresponding inhibitors have demonstrated potent modulatory effect on TME. Recent works have demonstrated that beyond the direct action on cancer cells, tyrosine kinase inhibitors (TKIs) have been implicated in inactivation or normalization of dysregulated TME components leading to cancer regression. Either through re-sensitizing the tumour cells or reversing the immunological tolerance microenvironment, the emergence of these TME modulatory mechanism of TKIs supports the combinatory use of TKIs with current chemotherapy or immunotherapy for cancer therapy. Therefore, an appropriate understanding on TME modulation by TKIs may offer another mode of action of TKIs for cancer treatment. This review highlights mode of kinase activation or paracrine ligand production from TME components and summarises the findings on the potential use of various TKIs on regulating TME components. At last, the combination use of current TKIs with immunotherapy in the perspectives of efficacy and safety are discussed.

Temozolomide toxicity operates in a xCT/SLC7a11 dependent manner and is fostered by ferroptosis

The glutamate exchanger xCT (SLC7a11) is causally linked with the malignancy grade of brain tumors and represents a key player in glutamate, cystine and glutathione metabolism. Although blocking xCT is not cytotoxic for brain tumors, xCT inhibition disrupts the neurodegenerative and microenvironment-toxifying activity of gliomas. Here, we report on the use of various xCT inhibitors as single modal drugs and in combination with the autophagy-inducing standard chemotherapeutic agent temozolomide (Temodal/Temcad®, TMZ). xCT overexpressing cells (xCT^OE) are more resistant to the FDA and EMA approved drug sulfasalazine (Azulfidine/Salazopyrin/Sulazine®, SAS) and RNAi-mediated xCT knock down (xCT^KD) in gliomas increases the susceptibility towards SAS in rodent gliomas. In human gliomas, challenged xCT expression had no impact on SAS-induced cytotoxicity. Noteworthy, other xCT inhibitors such as erastin and sorafenib showed enhanced efficacy on xCT^KD gliomas. In contrast, cytotoxic action of TMZ operates independently from xCT expression levels on rodent gliomas. Human glioma cells with silenced xCT expression display higher vulnerability towards TMZ alone as well as towards combined TMZ and SAS. Hence, we tested the partial xCT blockers and ferroptosis inducing agents erastin and sorafenib (Nexavar®, FDA and EMA-approved drug for lung cancer). Noteworthy, xCT^OE gliomas withstand erastin and sorafenib-induced cell death in a concentration-dependent manner, whereas siRNA-mediated xCT knock down increased susceptibility towards erastin and sorafenib. TMZ efficacy can be potentiated when combined with erastin, however not by sorafenib. Moreover, gliomas with high xCT expression are more vulnerable towards combinatorial treatment with erastin-temozolomide. These results disclose that ferroptosis inducers are valid compounds for potentiating the frontline therapeutic agent temozolomide in a multitoxic approach.

PRG3 induces Ras-dependent oncogenic cooperation in gliomas

Malignant gliomas are one of the most devastating cancers in humans. One characteristic hallmark of malignant gliomas is their cellular heterogeneity with frequent genetic lesions and disturbed gene expression levels conferring selective growth advantage. Here, we report on the neuronal-associated growth promoting gene PRG3 executing oncogenic cooperation in gliomas. We have identified perturbed PRG3 levels in human malignant brain tumors displaying either elevated or down-regulated PRG3 levels compared to non-transformed specimens. Further, imbalanced PRG3 levels in gliomas foster Ras-driven oncogenic amplification with increased proliferation and cell migration although angiogenesis was unaffected. Hence, PRG3 interacts with RasGEF1 (RasGRF1/CDC25), undergoes Ras-induced challenges, whereas deletion of the C-terminal domain of PRG3 (PRG3^ΔCT) inhibits Ras. Moreover PRG3 silencing makes gliomas resistant to Ras inhibition. In vivo disequilibrated PRG3 gliomas show aggravated proliferation, invasion, and deteriorate clinical outcome. Thus, our data show that the interference with PRG3 homeostasis amplifies oncogenic properties and foster the malignancy potential in gliomas.

Sulfasalazine impacts on ferroptotic cell death and alleviates the tumor microenvironment and glioma-induced brain edema

The glutamate transporter xCT (SCL7a11, system Xc-, SXC) is an emerging key player in glutamate/cysteine/glutathione homeostasis in the brain and in cancer. xCT expression correlates with the grade of malignancy. Here, we report on the use of the U.S. Food and Drug Administration and EMA-approved xCT inhibitor, sulfasalazine (SAS) in gliomas. SAS does not affect cell viability in gliomas at concentrations below 200 μM. At higher concentrations SAS becomes gliomatoxic. Mechanistically SAS inhibits xCT and induces ferroptotic cell death in glioma cells. There is no evidence for impact on autophagic flux following SAS application. However, SAS can potentiate the efficacy of the standard chemotherapeutic and autophagy-inducing agent temozolomide (Temcat, Temodal or Temodar®). We also investigated SAS in non-transformed cellular constituents of the brain. Neurons and brain tissue are almost non-responding to SAS whereas isolated astrocytes are less sensitive towards SAS toxicity compared to gliomas. In vivo SAS treatment does not affect experimental tumor growth and treated animals revealed comparable tumor volume as untreated controls. However, SAS treatment resulted in reduced glioma-derived edema and, hence, total tumor volume burden as revealed by T2-weighted magnetic resonance imaging. Altogether, we show that SAS can be utilized for targeting the glutamate antiporter xCT activity as a tumor microenvironment-normalizing drug, while crucial cytotoxic effects in brain tumors are minor.

Long-range and short-range tumor-stroma networks synergistically contribute to tumor-associated epilepsy

Epileptic seizures are frequently caused by brain tumors. Traditional anti-epileptic treatments do not acquire satisfactory responses. Preoperative and postoperative seizures seriously influence the quality of life of patients. Thus, tumor-associated epilepsy (TAE) is an important subject of the current research. The delineation of the etiology of epileptogenesis in patients with primary brain tumor may help to find the novel and effective drug targets for treating this disease. In this review, we describe the current status of treatment of TAE. More importantly, we focus on the factors that are involved in the functional connectivity between tumors and stromal cells. We propose that there exist two modes, namely, long-range and short-range modes, which likely trigger neuronal hyperexcitation and subsequent epileptic seizures. The long-range mode is referred to as factors released by tumors including glutamate and GABA, binding to the corresponding receptor on the cellular membrane and causing neuronal hyperactivity, while the short-range mode is considered to involve direct intracellular communication between tumor cells and stromas. Gap junctions and tunneling nanotube network are involved in cellular interconnections. Future investigations focused on those two modes may find a potential novel therapeutic target for treating TAE.

Evaluation of neovascularization patterns in an orthotopic rat glioma model with dynamic contrast-enhanced MRI

Background Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) has been proved useful in evaluating glioma angiogenesis, but the utility in evaluating neovascularization patterns has not been reported. Purpose To evaluate in vivo real-time glioma neovascularization patterns by measuring glioma perfusion quantitatively using DCE-MRI. Material and Methods Thirty Sprague-Dawley rats were used to establish C6 orthotopic glioma model and underwent MRI and pathology detections. As MRI and pathology were performed at six time points (i.e. 4, 8, 12, 16, 20, and 24 days) post transplantation, neovascularization patterns were evaluated via DCE-MRI. Results Four neovascularization patterns were observed in glioma tissues. Sprout angiogenesis and intussusceptive microvascular growth located inside tumor, while vascular co-option and vascular mimicry were found in the tumor margin and necrotic area, respectively. Sprout angiogenesis and intussusceptive microvascular growth increased with K_trans, K_ep, and V_p inside tumor tissue. In addition, K_ep and V_p were positively correlated with sprout angiogenesis and intussusceptive microvascular growth. Vascular co-option was decreased at 12 and 16 days post transplantation and correlated negatively with K_trans and K_ep detected in the glioma margin, respectively. Changes of vascular mimicry showed no significant statistical difference at the six time points. Conclusion Our results indicate that DCE-MRI can evaluate neovascularization patterns in a glioma model. Furthermore, DCE-MRI could be an imaging biomarker for guidance of antiangiogenic treatments in humans in the future.

Tumor Microenvironment in Treatment of Glioma

Glioma is one of the most malignant and fatal tumors in adults. Researchers and physicians endeavor to improve clinical efficacy towards it but made little achievement. In recent years, people have made advances in understanding characteristics and functions of tumor microenvironment and its role in different processes of tumor. In this paper, we describe the effects of tumor microenvironment on glioma proliferation, invasion and treatments. By explaining underlying mechanisms and enumerating new therapy strategies employing tumor microenvironment, we aim to provide novel ideas to improve clinical outcomes of glioma.

Inhibition of CYP4A by a novel flavonoid FLA-16 prolongs survival and normalizes tumor vasculature in glioma

Glioblastomas rapidly become refractory to anti-VEGF therapies. We previously showed that cytochrome P450 (CYP) 4A-derived 20-hydroxyeicosatetraenoic acid (20-HETE) promotes angiogenesis. Here, we tested whether a novel flavonoid (FLA-16) prolongs survival and normalizes tumor vasculature in glioma through CYP4A inhibition. FLA-16 improved survival, reduced tumor burden, and normalized vasculature, accompanied with the decreased secretion of 20-HETE, VEGF and TGF-β in tumor-associated macrophages (TAMs) and endothelial progenitor cells (EPCs) in C6 and U87 gliomas. FLA-16 attenuated vascular abnormalization induced by co-implantation of GL261 glioma cells with CYP4A10^high macrophages or EPCs. Mechanistically, the conditional medium from TAMs and EPCs treated with FLA-16 enhanced the migration of pericyte cells, and decreased the proliferation and migration of endothelial cells, which were reversed by CYP4A overexpression or exogenous addition of 20-HETE, VEGF and TGF-β. Furthermore, FLA-16 prevented crosstalk between TAMs and EPCs during angiogenesis. These results suggest that CYP4A inhibition by FLA-16 prolongs survival and normalizes vasculature in glioma through decreasing production of TAMs and EPCs-derived VEGF and TGF-β. This may represent a potential therapeutic strategy to overcome resistance to anti-VEGF treatment by effects on vessels and immune cells.

Cytotoxic profiling of artesunic and betulinic acids and their synthetic hybrid compound on neurons and gliomas

Gliomas are brain-born tumors with devastating impact on their brain microenvironment. Novel approaches employ multiple combinations of chemical compounds in synthetic hybrid molecules to target malignant tumors. Here, we report on the chemical hybridization approach exemplified by artesunic acid (ARTA) and naturally occurring triterpene betulinic acid (BETA). Artemisinin derived semisynthetic compound artesunic acid (ARTA) and naturally occurring triterpene BETA were used to synthetically couple to the hybrid compound termed 212A. We investigated the impact of 212A and its parent compounds on glioma cells, astrocytes and neurons. ARTA and BETA showed cytotoxic effects on glioma cells at micromolar concentrations. ARTA was more effective on rodent glioma cells compared to BETA, whereas BETA exhibited higher toxic effects on human glioma cells compared to ARTA. We investigated these compounds on non-transformed glial cells and neurons as well. Noteworthy, ARTA showed almost no toxic effects on astrocytes and neurons, whereas BETA as well as 212A displayed neurotoxicity at higher concentrations. Hence we compared the efficacy of the hybrid 212A with the combinational treatment of its parent compounds ARTA and BETA. The hybrid 212A was efficient in killing glioma cells compared to single compound treatment strategies. Moreover, ARTA and the hybrid 212A displayed a significant cytotoxic impact on glioma cell migration. Taken together, these results demonstrate that both plant derived compounds ARTA and BETA operate gliomatoxic with minor neurotoxic side effects. Altogether, our proof-of-principle study demonstrates that the chemical hybrid synthesis is a valid approach for generating efficacious anti-cancer drugs out of virtually any given structure. Thus, synthetic hybrid therapeutics emerge as an innovative field for new chemotherapeutic developments with low neurotoxic profile.

A versatile ex vivo technique for assaying tumor angiogenesis and microglia in the brain

Primary brain tumors are hallmarked for their destructive activity on the microenvironment and vasculature. However, solely few experimental techniques exist to access the tumor microenvironment under anatomical intact conditions with remaining cellular and extracellular composition. Here, we detail an ex vivo vascular glioma impact method (VOGIM) to investigate the influence of gliomas and chemotherapeutics on the tumor microenvironment and angiogenesis under conditions that closely resemble the in vivo situation. We generated organotypic brain slice cultures from rats and transgenic mice and implanted glioma cells expressing fluorescent reporter proteins. In the VOGIM, tumor-induced vessels presented the whole range of vascular pathologies and tumor zones as found in human primary brain tumor specimens. In contrast, non-transformed cells such as primary astrocytes do not alter the vessel architecture. Vascular characteristics with vessel branching, junctions and vessel meshes are quantitatively assessable as well as the peritumoral zone. In particular, the VOGIM resembles the brain tumor microenvironment with alterations of neurons, microglia and cell survival. Hence, this method allows live cell monitoring of virtually any fluorescence-reporter expressing cell. We further analyzed the vasculature and microglia under the influence of tumor cells and chemotherapeutics such as Temozolamide (Temodal/Temcad®). Noteworthy, temozolomide normalized vasculare junctions and branches as well as microglial distribution in tumor-implanted brains. Moreover, VOGIM can be facilitated for implementing the 3Rs in experimentations. In summary, the VOGIM represents a versatile and robust technique which allows the assessment of the brain tumor microenvironment with parameters such as angiogenesis, neuronal cell death and microglial activity at the morphological and quantitative level.

Sunitinib Possible Sex-Divergent Therapeutic Outcomes

Sunitinib is a tyrosine kinase inhibitor used for the treatment of renal cell carcinoma and metastatic brain tumors. Preclinical pharmacokinetic studies have shown higher sunitinib hepatic and brain exposure in female mice and higher sunitinib kidney concentrations in male mice. We explored whether sex-divergent tissue pharmacokinetics may anticipate sex-divergent therapeutic and toxicology responses in male and female patients. The review of the available scientific literature identified case reports, case series reports, clinical trials, and other studies associating sex with sunitinib outcomes. The results suggest male patients may respond better to renal cell carcinoma treatment and female patients may have better brain tumor treatment outcomes but a higher incidence of adverse events. Although more high-quality evidence is needed, these results, as anticipated by the preclinical data, may indicate possible sunitinib sex-divergent therapeutic outcomes in patients. In addition, we propose the systematic analysis of sex-based outcomes in clinical trial reports and their inclusion and review in the ethics committees and review boards to prevent, amongst others, patient burden in upcoming clinical trials.

Sunitinib DDI with paracetamol, diclofenac, mefenamic acid and ibuprofen shows sex-divergent effects on the tissue uptake and distribution pattern of sunitinib in mice

PURPOSE

Pharmacokinetic interaction of sunitinib with diclofenac, paracetamol, mefenamic acid and ibuprofen was evaluated due to their P450 mediated metabolism and OATP1B1, OATP1B3, ABCB1, ABCG2 transporters overlapping features.

METHODS

Male and female mice were administered 6 sunitinib doses (60 mg/kg) PO every 12 h and 30 min before the last dose were administered vehicle (control groups), 250 mg/kg paracetamol, 30 mg/kg diclofenac, 50 mg/kg mefenamic acid or 30 mg/kg ibuprofen (study groups), euthanized 6 h post last administration and sunitinib plasma, liver, kidney, brain concentrations analyzed.

RESULTS

Ibuprofen halved sunitinib plasma concentration in female mice (p < 0.01) and showed 59 % lower concentration than male mice (p < 0.05). Diclofenac and paracetamol female mice showed 45 and 25 % higher plasma concentrations than male mice which were 27 % lower in mefenamic acid female mice. Paracetamol increased 2.2 (p < 0.05) liver and 1.4-fold (p < 0.05) kidney sunitinib concentrations in male mice that were lower in female mice (p < 0.01, p < 0.001, respectively). Ibuprofen increased 2.9-fold (p < 0.01) liver concentration in male mice that were higher than in female mice (p < 0.001). Female control mice had 35 % higher sunitinib brain concentration than male mice but the concentration decreased 37, 33, 10 and 57 % in the diclofenac, paracetamol, mefenamic acid and ibuprofen (p < 0.001), respectively. Tissue-plasma concentrations correlations were nonsignificant in control, paracetamol, mefenamic acid and ibuprofen groups but was significant in the diclofenac group in male mice (liver, brain) and female mice (liver, kidney).

CONCLUSIONS

These results portray gender-based sunitinib pharmacokinetic differences and NSAIDs selective effects on male or female mice, with potential clinical translatability.