Evaluation of the efficiency of chemotherapy in in vivo orthotopic models of human glioma cells with and without 1p19q deletions and in C6 rat orthotopic allografts serving for the evaluation of surgery combined with chemotherapy

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.

Polygodial and Ophiobolin A Analogues for Covalent Crosslinking of Anticancer Targets

In a search of small molecules active against apoptosis-resistant cancer cells, including glioma, melanoma, and non-small cell lung cancer, we previously prepared α,β- and γ,δ-unsaturated ester analogues of polygodial and ophiobolin A, compounds capable of pyrrolylation of primary amines and demonstrating double-digit micromolar antiproliferative potencies in cancer cells. In the current work, we synthesized dimeric and trimeric variants of such compounds in an effort to discover compounds that could crosslink biological primary amine containing targets. We showed that such compounds retain the pyrrolylation ability and possess enhanced single-digit micromolar potencies toward apoptosis-resistant cancer cells. Target identification studies of these interesting compounds are underway.

One-Pot Synthesis of Novel Furochromone and Oxazocine Derivatives as Promising Antitumor Agents with Their Molecular Docking Studies

One-pot efficient synthesis of novel chromone derivatives 4a–h and that of 5a–h were described in a simple method via four-component reaction between furochromone carbaldehyde, amine, isocyanate derivatives, and benzoic acid derivatives or nicotinic acid, respectively. Also, oxazocine derivatives 7a, b were prepared via reaction of visnagine carbaldehyde, ethyl acetoacetate and isocyanate derivatives 2a, b. The obtained derivatives of novel furochromone and oxazocine derivatives were evaluated as promising antitumor agents against panel of two human cell lines, hepatocellular carcinoma (HEPG2) and breast carcinoma (MCF7). The antitumor results suggested that furochromone derivatives 5a–h have activity against MCF7 in comparison with doxorubicin as the standard drug. Furthermore, the molecular docking studies of these novel derivatives of furochromone and oxazocine showed good agreement with the biological results when their binding pattern and affinity towards the active site of EGFR was investigate.

Investigating the Mechanical Properties of Biological Brain Cells With Atomic Force Microscopy

Characterization of cell mechanical properties plays an important role in disease diagnoses and treatments. This paper uses advanced atomic force microscopy (AFM) to measure the geometrical and mechanical properties of two different human brain normal HNC-2 and cancer U87 MG cells. Based on experimental measurement, it measures the cell deformation and indentation force to characterize cell mechanical properties. A fitting algorithm is developed to generate the force-loading curves from experimental data. An inverse Hertzian method is also established to identify Young's moduli for HNC-2 and U87 MG cells. The results demonstrate that Young's modulus of cancer cells is different from that of normal cells, which can help us to differentiate normal and cancer cells from the biomechanical viewpoint.

Oligodendroglioma Cells Lack Glutamine Synthetase and Are Auxotrophic for Glutamine, but Do not Depend on Glutamine Anaplerosis for Growth

In cells derived from several types of cancer, a transcriptional program drives high consumption of glutamine (Gln), which is used for anaplerosis, leading to a metabolic addiction for the amino acid. Low or absent expression of Glutamine Synthetase (GS), the only enzyme that catalyzes de novo Gln synthesis, has been considered a marker of Gln-addicted cancers. In this study, two human cell lines derived from brain tumors with oligodendroglioma features, HOG and Hs683, have been shown to be GS-negative. Viability of both lines depends from extracellular Gln with EC50 of 0.175 ± 0.056 mM (Hs683) and 0.086 ± 0.043 mM (HOG), thus suggesting that small amounts of extracellular Gln are sufficient for OD cell growth. Gln starvation does not significantly affect the cell content of anaplerotic substrates, which, consistently, are not able to rescue cell growth, but causes hindrance of the Wnt/β-catenin pathway and protein synthesis attenuation, which is mitigated by transient GS expression. Gln transport inhibitors cause partial depletion of intracellular Gln and cell growth inhibition, but do not lower cell viability. Therefore, GS-negative human oligodendroglioma cells are Gln-auxotrophic but do not use the amino acid for anaplerosis and, hence, are not Gln addicted, exhibiting only limited Gln requirements for survival and growth.

A nitroalkane-based approach to one-pot three-component synthesis of isocryptolepine and its analogs with potent anti-cancer activities

A second generation polyphosphoric acid-mediated one-pot three-component synthesis of indoloquinoline scaffold is developed. This improved version of the process involves electrophilically activated nitroalkanes for the installation of strategic C–C and C–N bonds and ring C assembly. This modification allows the elimination of unnecessary solvent change operations and all steps are carried out in a true, uninterrupted one-pot manner. A further improvement involves the possibility to install an ortho-amino group in situ. A synthetic application of this method is showcased by the concise synthesis of an isocryptolepine alkaloid and its synthetic analogs with potent anticancer activities.

An improved one-pot three-component synthesis involving electrophilically activated nitroalkanes allowed for efficient preparation of indoloquinolines with potent anticancer activities.

Marine Terpenoid Diacylguanidines: Structure, Synthesis, and Biological Evaluation of Naturally Occurring Actinofide and Synthetic Analogues

A new diacylguanidine, actinofide (1), has been isolated from the marine mollusk Actinocyclus papillatus. The structure, exhibiting a guanidine moiety acylated by two terpenoid acid units, has been established by spectroscopic methods and secured by synthesis. Following this, a series of structural analogues have been synthesized using the same procedure. All of the compounds have been evaluated in vitro for the growth inhibitory activity against a variety of cancer cell lines.

Discovery and Characterization of R/S-N-3-Cyanophenyl-N'-(6-tert-butoxycarbonylamino-3,4-dihydro-2,2-dimethyl-2H-1-benzopyran-4-yl)urea, a New Histone Deacetylase Class III Inhibitor Exerting Antiproliferative Activity against Cancer Cell Lines

A new series of N-aryl-N'-3,4-dihydro-2,2-dimethyl-2H-1-benzopyran-4-yl)ureas bearing an alkoxycarbonylamino group at the 6-position were synthesized and examined as putative anticancer agents targeting sirtuins in glioma cells. On the basis of computational docking combined to in vitro sirtuin 1/2 inhibition assays, we selected compound 18 [R/S-N-3-cyanophenyl-N'-(6-tert-butoxycarbonylamino-3,4-dihydro-2,2-dimethyl-2H-1-benzopyran-4-yl)urea] which displays a potent antiproliferative activity on various glioma cell types, assessed by quantitative videomicroscopy, eventually triggering senescence. The impact on normal glial cells was lower with a selectivity index of >10. Furthermore, human U373 and Hs683 glioblastoma cell lines served to demonstrate the inhibitory activity of 18 against histone deacetylase (HDAC) class III sirtuins 1 and 2 (SIRT1/2) by quantifying acetylation levels of histone and non-histone proteins. The translational potential of 18 was validated by an NCI-60 cell line screen and validation of growth inhibition of drug resistant cancer cell models. Eventually, the anticancer potential of 18 was validated in 3D glioblastoma spheroids and in vivo by zebrafish xenografts. In summary, compound 18 is the first representative of a new class of SIRT inhibitors opening new perspectives in the medicinal chemistry of HDAC inhibitors.

A harmine-derived beta-carboline displays anti-cancer effects in vitro by targeting protein synthesis

Growing evidence indicates that protein synthesis is deregulated in cancer onset and progression and targeting this process might be a selective way to combat cancers. While harmine is known to inhibit DYRK1A and intercalate into the DNA, tri-substitution was shown previously to modify its activity profile in favor of protein synthesis inhibition. In this study, we thus evaluated the optimized derivative CM16 in vitro anti-cancer effects unfolding its protein synthesis inhibition activity. Indeed, the growth inhibitory profile of CM16 in the NCI 60-cancer-cell-line-panel correlated with those of other compounds described as protein synthesis inhibitors. Accordingly, CM16 decreased in a time- and concentration-dependent manner the translation of neosynthesized proteins in vitro while it did not affect mRNA transcription. CM16 rapidly penetrated into the cell in the perinuclear region of the endoplasmic reticulum where it appears to target translation initiation as highlighted by ribosomal disorganization. More precisely, we found that the mRNA expression levels of the initiation factors EIF1AX, EIF3E and EIF3H differ when comparing resistant or sensitive cell models to CM16. Additionally, CM16 induced eIF2α phosphorylation. Those effects could explain, at least partly, the CM16 cytostatic anti-cancer effects observed in vitro while neither cell cycle arrest nor DNA intercalation could be demonstrated. Therefore, targeting protein synthesis initiation with CM16 could represent a new promising alternative to current cancer therapies due to the specific alterations of the translation machinery in cancer cells as recently evidenced with respect to EIF1AX and eIF3 complex, the potential targets identified in this present study.

5,10b-Ethanophenanthridine amaryllidaceae alkaloids inspire the discovery of novel bicyclic ring systems with activity against drug resistant cancer cells

Plants of the Amaryllidaceae family produce a large variety of alkaloids and non-basic secondary metabolites, many of which are investigated for their promising anticancer activities. Of these, crinine-type alkaloids based on the 5,10b-ethanophenanthridine ring system were recently shown to be effective at inhibiting proliferation of cancer cells resistant to various pro-apoptotic stimuli and representing tumors with dismal prognoses refractory to current chemotherapy, such as glioma, melanoma, non-small-cell lung, esophageal, head and neck cancers, among others. Using this discovery as a starting point and taking advantage of a concise biomimetic route to the crinine skeleton, a collection of crinine analogues were synthetically prepared and evaluated against cancer cells. The compounds exhibited single-digit micromolar activities and retained this activity in a variety of drug-resistant cancer cell cultures. This investigation resulted in the discovery of new bicyclic ring systems with significant potential in the development of effective clinical cancer drugs capable of overcoming cancer chemotherapy resistance.

In Vitro Growth Inhibitory Activities of Natural Products from Irciniid Sponges against Cancer Cells: A Comparative Study

Marine sponges of the Irciniidae family contain both bioactive furanosesterterpene tetronic acids (FTAs) and prenylated hydroquinones (PHQs). Both classes of compounds are known for their anti-inflammatory, antioxidant, and antimicrobial properties and known to display growth inhibitory effects against various human tumor cell lines. However, the different experimental conditions of the reported in vitro bioassays, carried out on different cancer cell lines within separate studies, prevent realistic actual discrimination between the two classes of compounds from being carried out in terms of growth inhibitory effects. In the present work, a chemical investigation of irciniid sponges from Tunisian coasts led to the purification of three known FTAs and three known PHQs. The in vitro growth inhibitory properties of the six purified compounds have been evaluated in the same experiment in a panel of five human and one murine cancer cell lines displaying various levels of sensitivity to proapoptotic stimuli. Surprisingly, FTAs and PHQs elicited distinct profiles of growth inhibitory-responses, differing by one to two orders of magnitude in favor of the PHQs in all cell lines. The obtained comparative results are discussed in the light of a better selection of drug candidates from natural sources.

Theranostic Application of Mixed Gold and Superparamagnetic Iron Oxide Nanoparticle Micelles in Glioblastoma Multiforme

The treatment of glioblastoma multiforme, the most prevalent and lethal form of brain cancer in humans, has been limited in part by poor delivery of drugs through the blood-brain barrier and by unclear delineation of the extent of infiltrating tumor margins. Nanoparticles, which selectively accumulate in tumor tissue due to their leaky vasculature and the enhanced permeability and retention effect, have shown promise as both therapeutic and diagnostic agents for brain tumors. In particular, superparamagnetic iron oxide nanoparticles (SPIONs) have been leveraged as T2-weighted MRI contrast agents for tumor detection and imaging; and gold nanoparticles (AuNP) have been demonstrated as radiosensitizers capable of propagating electron and free radical-induced radiation damage to tumor cells. In this study, we investigated the potential applications of novel gold and SPION-loaded micelles (GSMs) coated by polyethylene glycol-polycaprolactone (PEG-PCL) polymer. By quantifying gh2ax DNA damage foci in glioblastoma cell lines, we tested the radiosensitizing efficacy of these GSMs, and found that GSM administration in conjunction with radiation therapy (RT) led to ~2-fold increase in density of double-stranded DNA breaks. For imaging, we used GSMs as a contrast agent for both computed tomography (CT) and magnetic resonance imaging (MRI) studies of stereotactically implanted GBM tumors in a mouse model, and found that MRI but not CT was sufficiently sensitive to detect and delineate tumor borders after administration and accumulation of GSMs. These results suggest that with further development and testing, GSMs may potentially be integrated into both imaging and treatment of brain tumors, serving a theranostic purpose as both an MRI-based contrast agent and a radiosensitizer.

Isatin derivatives with activity against apoptosis-resistant cancer cells

In a search of small molecules active against apoptosis-resistant cancer cells, a series of isatin-based heterocyclic compounds were synthesized and found to inhibit proliferation of cancer cell lines resistant to apoptosis. The synthesis of these compounds involved a condensation of commercially available, active methylene heterocycles with isatin proceeding in moderate to excellent yields. The heterocyclic scaffolds prepared in the current investigation appear to be a useful starting point for the development of agents to fight cancers with apoptosis resistance, and thus, associated with dismal prognoses.

Higginsianins A and B, Two Diterpenoid α-Pyrones Produced by Colletotrichum higginsianum, with in Vitro Cytostatic Activity

Two new diterpenoid α-pyrones, named higginsianins A (1) and B (2), were isolated from the mycelium of the fungus Colletotrichum higginsianum grown in liquid culture. They were characterized as 3-[5a,9b-dimethyl-7-methylene-2-(2-methylpropenyl)dodecahydronaphtho[2,1-b]furan-6-ylmethyl]-4-hydroxy-5,6-dimethylpyran-2-one and 4-hydroxy-3-[6-hydroxy-5,8a-dimethyl-2-methylene-5-(4-methylpent-3-enyl)decahydronaphthalen-1-ylmethyl]-5,6-dimethylpyran-2-one, respectively, by using NMR, HRESIMS, and chemical methods. The structure and relative configuration of higginsianin A (1) were confirmed by X-ray diffractometric analysis, while its absolute configuration was assigned by electronic circular dichroism (ECD) experiments and calculations using a solid-state ECD/TDDFT method. The relative and absolute configuration of higginsianin B (2), which did not afford crystals suitable for X-ray analysis, were determined by NMR analysis and by ECD in comparison with higginsianin A. 1 and 2 were the C-8 epimers of subglutinol A and diterpenoid BR-050, respectively. The evaluation of 1 and 2 for antiproliferative activity against a panel of six cancer cell lines revealed that the IC50 values, obtained with cells reported to be sensitive to pro-apoptotic stimuli, are by more than 1 order of magnitude lower than their apoptosis-resistant counterparts (1 vs >80 μM). Finally, three hemisynthetic derivatives of 1 were prepared and evaluated for antiproliferative activity. Two of these possessed IC50 values and differential sensitivity profiles similar to those of 1.

Molecular-genetic and clinical characteristics of gliomas with astrocytic appearance and total 1p19q loss in a single institutional consecutive cohort

The prognostic significance of 1p19q loss in astrocytic gliomas has been inconclusive.We collected 57 gliomas with total 1p19q loss from among 218 cases of WHO grade-II/III gliomas operated at Keio University Hospital between 1990 and 2010. These tumors were classified as oligodendroglial or "astrocytic" by a WHO-criteria-based institutional diagnosis. Chromosomal copy number aberrations (CNAs), IDH 1/2 mutations, MGMT promoter methylation, and expression of p53 and ATRX were assessed. Survival outcome was compared between the two histological groups.Of the 57 codeleted gliomas, 37, 16, and four were classified as oligodendroglial, "astrocytic", and unclassified, respectively. Comparative genomic hybridization revealed that although chromosome 7q/7 gain was more frequent in "astrocytic" gliomas, other CNAs occurred at a similar frequency in both groups. None of the "astrocytic" gliomas showed p53 accumulation, and ATRX loss was found in three of the 15 "astrocytic" gliomas. The estimated overall survival (OS) curves in the patients with codeleted oligodendroglial and "astrocytic" gliomas overlapped, and the median OS was 187 and 184 months, respectively. Histopathological re-assessment by a single pathologist showed consistent results.Gliomas with total 1p19q loss with "astrocytic" features have molecular and biological characteristics comparable to those of oligodendroglial tumors.

Jonquailine, a new pretazettine-type alkaloid isolated from Narcissus jonquilla quail, with activity against drug-resistant cancer

A new alkaloid, belonging to the pretazettine group of Amaryllidaceae alkaloids, was isolated from dried bulbs of Narcissus jonquilla quail and named jonquailine. Its structure, including the absolute configuration, was elucidated using various NMR, ECD and ESI MS techniques. Initial biological evaluation revealed significant antiproliferative effects against glioblastoma, melanoma, uterine sarcoma and non-small-cell lung cancer cells displaying various forms of drug resistance, including resistance to apoptosis and multi-drug resistance. Jonquailine was also found to synergize with paclitaxel in its antiproliferative action against drug-resistant lung cancer cells. The results obtained compared with literature data also showed that the hydroxylation at C-8 is an important feature for the anticancer activity but this seems unaffected by the stereochemistry or the acetalization of the lactol.

Synthesis and in vitro antiproliferative activity of amido and amino analogues of the marine alkaloid isogranulatimide

Marine organisms have proven to be a promising source of new compounds with activity against tumor cell lines. Granulatimide and isogranulatimide are marine alkaloids that have been shown to inhibit checkpoint kinase 1 (Chk1), a key protein in the DNA damage response and an emerging target for anticancer therapeutics. Here, we describe the synthesis and preliminary evaluation of amido and amino analogues of isogranulatimide. The new derivatives were prepared in three steps from 2-imidazol-1-yl-1H-indol-5-ylamine. Two of the compounds synthesized exhibited more potent in vitro antiproliferative activity (single-digit micromolar concentration range), by at least one log of magnitude, than the natural product isogranulatimide when evaluated in six human tumor cell lines: non-small-cell lung cancer (A549), colon cancer (LoVo), breast cancer (MCF7), oligodendroglioma (Hs683), glioblastoma (U373), and melanoma (SKMEL28). The mechanism of action of these derivatives remains to be elucidated, given that they did not significantly inhibit Chk1, however these compounds are easily synthesized and exhibit potent anticancer activity and are thus worthy of further study.

Activity of 2-aryl-2-(3-indolyl)acetohydroxamates against drug-resistant cancer cells

Many types of tumor, including glioma, melanoma, non-small cell lung, esophageal, and head and neck cancer, among others, are intrinsically resistant to apoptosis induction and poorly responsive to current therapies with proapoptotic agents. In addition, tumors often develop multidrug resistance based on the cellular efflux of chemotherapeutic agents. Thus, novel anticancer agents capable of overcoming these intrinsic or developed tumor resistance mechanisms are urgently needed. We describe a series of 2-aryl-2-(3-indolyl)acetohydroxamic acids that are active against apoptosis- and multidrug-resistant cancer cells as well as glioblastoma neurosphere stemlike cell cultures derived from patients. Thus, the described compounds serve as a novel chemical scaffold for the development of potentially highly effective clinical cancer drugs.

In vivo and ex vivo assessment of the blood brain barrier integrity in different glioblastoma animal models

Blood brain barrier (BBB) disruption is used (pre)clinically as a measure for brain tumor malignancy and grading. During treatment it is one of the parameters followed rigorously to assess therapeutic efficacy. In animal models, both invasive and non-invasive methods are used to determine BBB disruption, among them Evans blue injection prior to sacrifice and T1-weighted magnetic resonance imaging (MRI) post contrast injection. In this study, we have assessed the BBB integrity with the methods mentioned above in two experimental high grade glioma models, namely the GL261 mouse glioblastoma model and the Hs683 human oligodendroglioma model. The GL261 model showed clear BBB integrity loss with both, contrast-enhanced (CE) MRI and Evans blue staining. In contrast, the Hs683 model only displayed BBB disruption with CE-MRI, which was not evident on Evans blue staining, indicating a limited BBB disruption. These results clearly indicate the importance of assessing the BBB integrity status using appropriate methods. Especially when using large therapeutic molecules that have difficulties crossing the BBB, care should be taken with the appropriate BBB disruption assessment studies.

Synthetic and biological studies of tubulin targeting c2-substituted 7-deazahypoxanthines derived from marine alkaloid rigidins

C2-aryl- and C2-alkyl-7-deazahypoxanthines as analogues of marine alkaloid rigidins were prepared utilizing novel synthetic methods developed for the construction of the pyrrolo[2,3-d]pyrimidine ring system. The new compounds exhibited sub-micromolar to nanomolar antiproliferative potencies against a panel of cell lines including in vitro models for drug-resistant tumors, such as glioblastoma, melanoma and non-small-cell lung cancer. A selected representative C2-methyl-7-deazahypoxanthine was found to inhibit microtubule dynamics in cancer cells, lending evidence for tubulin targeting as a mode of action for these compounds in cancer cells. The results of the docking studies utilizing the colchicine site on β-tubulin were consistent with the observed structure-activity relationship data, including an important finding that derivatization at C2 with linear alkyl groups leads to the retention of activity, thus permitting the attachment of a biotin-containing linker for the subsequent proteomics assays. Because many microtubule-targeting compounds are successfully used to fight cancer in the clinic, the reported antitubulin rigidin analogues have significant potential as new anticancer agents.

C1,C2-ether derivatives of the Amaryllidaceae alkaloid lycorine: retention of activity of highly lipophilic analogues against cancer cells

As a continuation of the studies aimed at the development of new anticancer agents derived from the Amaryllidaceae alkaloid lycorine, 35 C1,C2-ether analogues of this natural product were synthesized. The compounds were evaluated for antiproliferative activities in vitro in a panel of tumor cell lines with varied levels of apoptosis resistance. A strong correlation between the compound lipophilicity and anticancer activity was observed, indicating that cell permeability properties must be an important determinant in the design of lycorine-based anticancer agents. A theoretical docking model, consistent with the experimental observations, is presented.

Tumor versus stromal cells in culture--survival of the fittest?

Two of the signature genetic events that occur in human gliomas, EGFR amplification and IDH mutation, are poorly represented in experimental models in vitro. EGFR amplification, for example, occurs in 40 to 50% of GBM, and yet, EGFR amplification is rarely preserved in cell cultures derived from human tumors. To analyze the fate of EGFR amplified and IDH mutated cells in culture, we followed the development over time of cultures derived from human xenografts in nude rats enriched for tumor cells with EGFR amplification and of cultures derived from patient samples with IDH mutations, in serum monolayer and spheroid suspension culture, under serum and serum free conditions. We observed under serum monolayer conditions, that nestin positive or nestin and SMA double positive rat stromal cells outgrew EGFR amplified tumor cells, while serum spheroid cultures preserved tumor cells with EGFR amplification. Serum free suspension culture exhibited a more variable cell composition in that the resultant cell populations were either predominantly nestin/SOX2 co-expressing rat stromal cells or human tumor cells, or a mixture of both. The selection for nestin/SMA positive stromal cells under serum monolayer conditions was also consistently observed in human oligodendrogliomas and oligoastrocytomas with IDH mutations. Our results highlight for the first time that serum monolayer conditions can select for stromal cells instead of tumor cells in certain brain tumor subtypes. This result has an important impact on the establishment of new tumor cell cultures from brain tumors and raises the question of the proper conditions for the growth of the tumor cell populations of interest.

Role of endothelin B receptor in oligodendroglioma proliferation and survival: In vitro and in vivo evidence

In this study, the role of the endothelin B receptor (ETBR) in oligodendroglioma cell proliferation and survival was investigated in vitro and in vivo. The overexpression and knockdown of ETBR was conducted in Hs683 human oligodendroglioma cells, and cell proliferation and activation (phosphorylation) of extracellular signal-regulated kinase (ERK) were measured in vitro. An orthotopic xenograft oligodendroglioma mouse model was established. Mouse survival times and immunohistochemical Ki67 staining in the xenografts were examined. In vitro experiments demonstrated that the overexpression of ETBR significantly enhanced the proliferation of oligodendroglioma cells and the activation of ERK compared with the controls, which was eliminated by the selective ETBR inhibitor BQ788 and ERK-specific inhibitor U0126, but not selective endothelin A receptor inhibitor BQ123. By contrast, the knockdown of endogenous ETBR markedly decreased oligodendroglioma cell proliferation and the activation of ERK compared with the controls. Overexpression of ETBR significantly increased immunohistochemical Ki67 staining in the Hs683 cell orthotopic xenograft and decreased animal survival. By contrast, knockdown of ETBR significantly decreased Ki67 staining and increased mouse survival times. Intratumoral injection of BQ788, but not BQ123, significantly decreased Ki67 staining and prolonged mouse survival times. In conclusion, ETBR was demonstrated to mediate the proliferation of oligodendroglioma cells according to an ERK-dependent mechanism. Using an orthotopic xenograft oligodendroglioma mouse model, it was demonstrated in vivo that ETBR promotes oligodendroglioma proliferation and that the selective ETBR antagonist effectively inhibits the proliferation of oligodendroglioma cells and prolongs survival times. This study provides a novel insight into the role of ETBR in oligodendroglioma proliferation and survival, and provides the first in vivo evidence that ETBR-specific antagonists are a potential therapeutic alternative for oligodendrogliomas.

In vitro pharmacological and toxicological effects of norterpene peroxides isolated from the Red Sea sponge Diacarnus erythraeanus on normal and cancer cells

Eight cyclic peroxide norterpenoids, compounds 1-8, have been isolated and characterized from the Red Sea sponge Diacarnus erythraeanus, including two new norsesterterpene derivatives (3, 4). Among these metabolites, (-)-muqubilin A (5) (nine cell lines analyzed) and the new compounds 3 and 4 (seven cell lines analyzed) displayed mean IC₅₀ growth inhibitory concentrations in vitro of <10 μM, while the remaining compounds (1, 6-8) were inactive in these cancer cell lines. Compound 5 displayed no selectivity between normal and cancer cells in terms of in vitro growth inhibition. Quantitative video microscopy analysis carried out on (-)-muqubilin A-treated cells validated the data obtained by means of the MTT colorimetric assay, while flow cytometry analysis revealed ROS production but no induction of apoptosis in cancer cells.

Hellebrin and its aglycone form hellebrigenin display similar in vitro growth inhibitory effects in cancer cells and binding profiles to the alpha subunits of the Na+/K+-ATPase

BACKGROUND

Surface-expressed Na+/K+-ATPase (NaK) has been suggested to function as a non-canonical cardiotonic steroid-binding receptor that activates multiple signaling cascades, especially in cancer cells. By contrast, the current study establishes a clear correlation between the IC50in vitro growth inhibitory concentration in human cancer cells and the Ki for the inhibition of activity of purified human α1β1 NaK.

METHODS

The in vitro growth inhibitory effects of seven cardiac glycosides including five cardenolides (ouabain, digoxin, digitoxin, gitoxin, uzarigenin-rhamnoside, and their respective aglycone forms) and two bufadienolides (gamabufotalin-rhamnoside and hellebrin, and their respective aglycone forms) were determined by means of the MTT colorimetric assay and hellebrigenin-induced cytotoxic effects were visualized by means of quantitative videomicroscopy. The binding affinity of ten of the 14 compounds under study was determined with respect to human α1β1, α2β1 and α3β1 NaK complexes. Lactate releases and oxygen consumption rates were also determined in cancer cells treated with these various cardiac glycosides.

RESULTS

Although cardiotonic steroid aglycones usually display weaker binding affinity and in vitro anticancer activity than the corresponding glycoside, the current study demonstrates that the hellebrin / hellebrigenin pair is at odds with respect to this rule. In addition, while some cardiac steroid glycosides (e.g., digoxin), but not the aglycones, display a higher binding affinity for the α2β1 and α3β1 than for the α1β1 complex, both hellebrin and its aglycone hellebrigenin display ~2-fold higher binding affinity for α1β1 than for the α2β1 and α3β1 complexes. Finally, the current study highlights a common feature for all cardiotonic steroids analyzed here, namely a dramatic reduction in the oxygen consumption rate in cardenolide- and bufadienolide-treated cells, reflecting a direct impact on mitochondrial oxidative phosphorylation.

CONCLUSIONS

Altogether, these data show that the binding affinity of the bufadienolides and cardenolides under study is usually higher for the α2β1 and α3β1 than for the α1β1 NaK complex, excepted for hellebrin and its aglycone form, hellebrigenin, with hellebrigenin being as potent as hellebrin in inhibiting in vitro cancer cell growth.

Antiproliferative activity of 2,3-disubstituted indoles toward apoptosis-resistant cancers cells

Many types of cancer, including glioma, melanoma, NSCLC, among others, are resistant to apoptosis induction and poorly responsive to current therapies with propaptotic agents. We describe a series of 2,3-disubstituted indoles, which display cytostatic rather than cytotoxic effects in cancer cells, and serve as a new chemical scaffold to develop anticancer agents capable of combating apoptosis-resistant cancers associated with dismal prognoses.

A novel, diffusely infiltrative xenograft model of human anaplastic oligodendroglioma with mutations in FUBP1, CIC, and IDH1

Oligodendroglioma poses a biological conundrum for malignant adult human gliomas: it is a tumor type that is universally incurable for patients, and yet, only a few of the human tumors have been established as cell populations in vitro or as intracranial xenografts in vivo. Their survival, thus, may emerge only within a specific environmental context. To determine the fate of human oligodendroglioma in an experimental model, we studied the development of an anaplastic tumor after intracranial implantation into enhanced green fluorescent protein (eGFP) positive NOD/SCID mice. Remarkably after nearly nine months, the tumor not only engrafted, but it also retained classic histological and genetic features of human oligodendroglioma, in particular cells with a clear cytoplasm, showing an infiltrative growth pattern, and harboring mutations of IDH1 (R132H) and of the tumor suppressor genes, FUBP1 and CIC. The xenografts were highly invasive, exhibiting a distinct migration and growth pattern around neurons, especially in the hippocampus, and following white matter tracts of the corpus callosum with tumor cells accumulating around established vasculature. Although tumors exhibited a high growth fraction in vivo, neither cells from the original patient tumor nor the xenograft exhibited significant growth in vitro over a six-month period. This glioma xenograft is the first to display a pure oligodendroglioma histology and expression of R132H. The unexpected property, that the cells fail to grow in vitro even after passage through the mouse, allows us to uniquely investigate the relationship of this oligodendroglioma with the in vivo microenvironment.

Ceramide, cerebroside and triterpenoid saponin from the bark of aerial roots of Ficus elastica (Moraceae)

Three compounds, ficusamide (1), ficusoside (2) and elasticoside (3), were isolated from the bark of aerial roots of Ficus elastica (Moraceae), together with nine known compounds, including four triterpenes, three steroids and two aliphatic linear alcohols. The chemical structures of the three compounds were established by extensive 1D and 2D NMR spectroscopy, mass spectrometry and by comparison with published data. The growth inhibitory effect of the crude extract and isolated compounds was evaluated against several microorganisms and fungi. The cytotoxicity against human cancer cell lines was also assessed. Ficusamide (1) displayed a moderate in vitro growth inhibitory activity against the human A549 lung cancer cell line and a strong activity against Staphylococcus saprophyticus, while elasticoside (3) showed a potent activity on Enterococcus faecalis.

FTIR spectroscopy: a new valuable tool to classify the effects of polyphenolic compounds on cancer cells

Polyphenolic compounds are an important part of human diet and regular consumption of fruits, vegetables and tea is associated with reduced risk of cancer. Dietary polyphenols display a vast array of cellular effects but the large number of data published in the literature makes it difficult to determine the main mechanisms of action associated and to identify molecules with original mechanisms. Therefore, there is an increasing demand for more systemic approaches in order to obtain a global insight of the biochemical processes mediated by polyphenols. Here, we used Fourier transform infrared (FTIR) spectroscopy to analyze cancer cells exposed in vitro to 6 polyphenols: 3 natural well documented polyphenols (curcumin, epigallocatechin gallate (EGCG) and quercetin) and 3 synthetic molecules with a very closely related chemical structure. Statistical analyses on FTIR spectra allowed the comparison of global effects of the 6 compounds and evidenced some common or different features in the cell perturbations among natural and synthetic molecules. Interestingly, marked metabolic changes induced by polyphenols closely related from a chemical point of view were identified. Furthermore, many metabolic changes could be detected as early as after 2h incubation with the drugs.

Sparc-like protein 1 is a new marker of human glioma progression

High-grade gliomas (glioblastomas) are the most common and deadly brain tumors in adults, currently with no satisfactory treatment available. Apart from de novo glioblastoma, it is currently accepted that these malignancies mainly progress from lower grade glial tumors. However, the molecular entities governing the progression of gliomas are poorly understood. Extracellular and membrane proteins are key biomolecules found at the cell-to-cell communication interface and hence are a promising proteome subpopulation that could help understand the development of glioma. Accordingly, the current study aims at identifying new protein markers of human glioma progression. For this purpose, we used glial tumors generated orthotopically with T98G and U373 human glioma cells in nude mice. This setup allowed also to discriminate the protein origin, namely, human (tumor) or mouse (host). Extracellular and membrane proteins were selectively purified using biotinylation followed by streptavidin affinity chromatography. Isolated proteins were digested and then identified and quantified employing 2D-nano-HPLC-MS/MS analysis. A total of 23 and 27 up-regulated extracellular and membrane proteins were identified in the T98G and U373 models, respectively. Approximately two-thirds of these were predominantly produced by the tumor, whereas the remaining proteins appeared to be mainly overexpressed by the host tissue. Following extensive validation, we have focused our attention on sparc-like protein 1. This protein was further investigated using immunohistochemistry in a large collection of human glioma samples of different grades. The results showed that sparc-like protein 1 expression correlates with glioma grade, suggesting the possible role for this protein in the progression of this malignancy.

Chemistry of the nudibranch Aldisa andersoni: structure and biological activity of phorbazole metabolites

The first chemical study of the Indo-Pacific dorid nudibranch Aldisa andersoni resulted in the isolation of five chlorinated phenyl-pyrrolyloxazoles belonging to the phorbazole series. Two new molecules, 9-chloro-phorbazole D and N1-methyl-phorbazole A, co-occurring with known phorbazoles A, B and D, have been characterized. Phorbazoles were found to be present mainly in the external part of the mollusc. The structures of the new compounds were determined by interpretation of spectroscopic data, mainly NMR and mass spectrometry and by comparison with the literature data. Evaluation of feeding-deterrence activity as well as in vitro growth inhibitory properties in human cancer cells was also carried out.

Novel trisubstituted harmine derivatives with original in vitro anticancer activity

To overcome the intrinsic resistance of cancer cells to apoptotic stimuli, we designed and synthesized approximately 50 novel β-carbolines structurally related to harmine. Harmine is known for its anticancer properties and is a DYRK1A inhibitor. Of the synthesized compounds, the most active in terms of growth inhibition of five cancer cell lines are cytostatic and approximately 100 times more potent than harmine but demonstrated no DYRK1A inhibitory activity. These novel β-carbolines display similar growth inhibitory activity in cancer cells that are sensitive and resistant to apoptotic stimuli. Using ChemGPS-NP, we found that the more active β-carbolines are all more lipophilic and larger than the less active compounds. Lastly, on the basis of the NCI human tumor cell line anticancer drug screen and the NCI COMPARE algorithm, it appears that some of these compounds, including 5a and 5k, seem to act as protein synthesis inhibitors.

[Animal models of human glioma: the progress of application and investigation]

The glioma accounts for half of the central nervous tumors, among which the glioblastoma multiforme (GBM) is one of the most aggressive and lethal brain tumors. The difficulties in glioma therapy indicate the need of appropriate animal models for preclinical studies. Benefiting from the development of molecular biology, genetics, and transgenic technology, variable animal models of glioma have been established. These animal models of human glioma are reviewed in this paper.

Bulbispermine: a crinine-type Amaryllidaceae alkaloid exhibiting cytostatic activity toward apoptosis-resistant glioma cells

The Amaryllidaceae alkaloid bulbispermine was derivatized to produce a small group of synthetic analogues. These, together with bulbispermine's natural crinine-type congeners, were evaluated in vitro against a panel of cancer cell lines with various levels of resistance to pro-apoptotic stimuli. Bulbispermine, haemanthamine, and haemanthidine showed the most potent antiproliferative activities as determined by the MTT colorimetric assay. Among the synthetic bulbispermine analogues, only the C1,C2-dicarbamate derivative exhibited notable growth inhibitory properties. All active compounds were found not to discriminate between the cancer cell lines based on the apoptosis sensitivity criterion; they displayed similar potencies in both cell types, indicating that the induction of apoptosis is not the primary mechanism responsible for antiproliferative activity in this series of compounds. It was also found that bulbispermine inhibits the proliferation of glioblastoma cells through cytostatic effects, possibly arising from rigidification of the actin cytoskeleton. These findings lead us to argue that crinine-type alkaloids are potentially useful drug leads for the treatment of apoptosis-resistant cancers and glioblastoma in particular.

Potential anticancer activity of young Carpinus betulus leaves

As part of our continuing research for anticancer compounds from the Walloon Region forest, EtOAc extract from Carpinus betulus leaves was phytochemically studied, leading to the bioguided isolation of pheophorbide a, which is responsible of anticancer properties of C. betulus young leaves. This compound was identified using nuclear magnetic resonance and mass spectrophotometric data and comparison with a commercial standard. Evaluation of the growth inhibitory activities of pheophorbide a using MTT colorimetric assay and phase-contrast microscopy in various human cancer cell lines confirmed the photoactivable properties of this compound. Our research showed, for the first time, the presence of pheophorbide a, a chlorophyll derived compound, which we quantified in high quantities in young leaves of C. betulus. This is in contrast with the literature which generally describes pheophorbide a as a catabolic product of chlorophyll, then preferentially present in old leaves.

Downregulation of PRDX1 by promoter hypermethylation is frequent in 1p/19q-deleted oligodendroglial tumours and increases radio- and chemosensitivity of Hs683 glioma cells in vitro

Deletions of chromosomal arms 1p and 19q are frequent in oligodendroglial tumours and linked to radio- and chemotherapy response as well as longer survival. The molecular mechanisms underlying this clinically important association are as yet unknown. Here, we studied the peroxiredoxin 1 (PRDX1) gene at 1p34.1 for promoter methylation and expression in primary gliomas and investigated its role in radio- and chemosensitivity of glioma cells in vitro. In total, we screened primary glioma tissues from 93 patients for methylation of the 5'-CpG island of PRDX1 by sodium bisulfite sequencing. PRDX1 mRNA and protein expression levels were determined in subsets of the tumours by quantitative PCR and western blot analysis, respectively. PRDX1 hypermethylation and reduced expression were frequently detected in oligodendroglial tumours and secondary glioblastomas, but not in primary glioblastomas. In oligodendroglial tumours, both PRDX1 hypermethylation and reduced mRNA expression were significantly associated with 1p/19q-deletion. Stable knockdown of PRDX1 by lentiviral transduction of short-hairpin (sh)RNA constructs significantly increased apoptosis and reduced cell viability of Hs683 glioma cells exposed to ionizing irradiation or temozolomide in vitro. Taken together, our findings indicate that epigenetic silencing of PRDX1 is frequent in 1p/19q-deleted oligodendroglial tumours and likely contributes to radio- and chemosensitivity of these tumours.

In search of a cytostatic agent derived from the alkaloid lycorine: synthesis and growth inhibitory properties of lycorine derivatives

As a continuation of our studies aimed at the development of a new cytostatic agent derived from an Amaryllidaceae alkaloid lycorine, we synthesized 32 analogues of this natural product. This set of synthetic analogues included compounds incorporating selective derivatization of the C1 versus C2 hydroxyl groups, aromatized ring C, lactamized N6 nitrogen, dihydroxylated C3-C3a olefin functionality, transposed olefin from C3-C3a to C2-C3 or C3a-C4, and C1 long-chain fatty esters. All synthesized compounds were evaluated for antiproliferative activities in vitro in a panel of tumor cell lines including those exhibiting resistance to proapoptotic stimuli and representing solid cancers associated with dismal prognoses, such as melanoma, glioblastoma, and non-small-cell lung cancer. Most active analogues were not discriminatory between cancer cells displaying resistance or sensitivity to apoptosis, indicating that these compounds are thus able to overcome the intrinsic resistance of cancer cells to pro-apoptotic stimuli. 1,2-Di-O-allyllycorine was identified as a lycorine analogue, which is 100 times more potent against a U373 human glioblastoma model than the parent natural product. Furthermore, a number of synthetic analogues were identified as promising for the forthcoming in vivo studies.

Antitumoral activity of allosteric inhibitors of protein kinase CK2

INTRODUCTION

Due to its physiological role into promoting cell survival and its dysregulation in most cancer cells, protein kinase CK2 is a relevant physiopathological target for development of chemical inhibitors. We report the discovery of azonaphthalene derivatives, as a new family of highly specific CK2 inhibitors. First, we demonstrated that CK2 inhibition (IC50= 0.4 µM) was highly specific, reversible and non ATP-competitive. Small Angle X-ray Scattering experiments showed that this inhibition was due to large conformational change of CK2α upon binding of these inhibitors. We showed that several compounds of the family were cell-potent CK2 inhibitors promoting cell cycle arrest of human glioblastoma U373 cells. Finally, in vitro and in vivo assays showed that these compounds could decrease U373 cell tumor mass by 83 % emphasizing their efficacy against these apoptosis-resistant tumors. In contrast, Azonaphthalene derivatives inactive on CK2 activity showed no effect in colony formation and tumor regression assays. These findings illustrate the emergence of nonclassical CK2 inhibitors and provide exciting opportunities for the development of novel allosteric CK2 inhibitors.

BACKGROUND

CK2 is an emerging therapeutic target and ATP-competitive inhibitors have been identified. CK2 is endowed with specific structural features providing alternative strategies for inhibition.

RESULTS

Azonaphthalene compounds are allosteric CK2 inhibitors showing antitumor activity.

CONCLUSION

CK2 may be targeted allosterically.

SIGNIFICANCE

These inhibitors provide a foundation for a new paradigm for specific CK2 inhibition.

Evaluation of the antiproliferative activity of diterpene isonitriles from the sponge Pseudoaxinella flava in apoptosis-sensitive and apoptosis-resistant cancer cell lines

One new (1) and three known (2-4) isonitrile diterpenes, isolated from the Caribbean sponge Pseudoaxinella flava, were assayed in human cancer cell lines in vitro using an MTT colorimetric assay and quantitative videomicroscopy. Compounds 1-4 displayed activity for human PC3 prostate apoptosis-sensitive cancer cell lines. Compounds 3 and 4 demonstrated similar growth inhibitory effects for three apoptosis-sensitive and three apoptosis-resistant cancer cell lines. Quantitative videomicroscopy analysis revealed that compounds 1 and 2 exerted their activity through cytotoxic effects, and compounds 3 and 4 through cytostatic effects. These results identify marine diterpene isonitriles as potential lead compounds for anticancer drug discovery.

Current review of in vivo GBM rodent models: emphasis on the CNS-1 tumour model

GBM (glioblastoma multiforme) is a highly aggressive brain tumour with very poor prognosis despite multi-modalities of treatment. Furthermore, recent failure of targeted therapy for these tumours highlights the need of appropriate rodent models for preclinical studies. In this review, we highlight the most commonly used rodent models (U251, U86, GL261, C6, 9L and CNS-1) with a focus on the pathological and genetic similarities to the human disease. We end with a comprehensive review of the CNS-1 rodent model.

JLK1486, a Bis 8-Hydroxyquinoline-Substituted Benzylamine, Displays Cytostatic Effects in Experimental Gliomas through MyT1 and STAT1 Activation and, to a Lesser Extent, PPARγ Activation

Gliomas account for 5% to 7% of all solid cancers in adults and up to 30% of solid cancers in children; glioblastomas are the most malignant type of glioma and often have dismal prognoses. The alkylating agent temozolomide provides the greatest chemotherapeutic benefits currently available; however, glioblastoma patients cannot be cured. Novel drugs that efficiently combat glioblastomas are therefore of great interest. We report here that JLK1486, an 8-hydroxyquinoline-substituted benzylamine, could represent a novel chemical scaffold to reach this goal. Indeed, JLK1486 mediated anticancer activity in vivo (through intravenous as well as oral routes of administrations) in an orthotopic xenograft model and displayed efficiency similar to that of temozolomide. The therapeutic benefits of JLK1486 seem to relate to its ability to activate various transcription factors (including Myt1, STAT1, and peroxisome proliferator-activated receptor γ) in glioma cells. These transcription factors are implicated in the control of glioma cell proliferation, and the resultant global effect of their activation by JLK1486 was cytostatic, not cytotoxic. Thus, the current study opens the door for the development of novel compounds to combat glioblastoma using 8-hydroxyquinoline benzylamine analogs.