Enhanced antitumor efficacy of biocompatible magnetosomes for the magnetic hyperthermia treatment of glioblastoma.

In this study, biologically synthesized iron oxide nanoparticles, called magnetosomes, are made fully biocompatible by removing potentially toxic organic bacterial residues such as endotoxins at magnetosome mineral core surfaces and by coating such surface with poly-L-lysine, leading to magnetosomes-poly-L-lysine (M-PLL). M-PLL antitumor efficacy is compared with that of chemically synthesized iron oxide nanoparticles (IONPs) currently used for magnetic hyperthermia. M-PLL and IONPs are tested for the treatment of glioblastoma, a dreadful cancer, in which intratumor nanoparticle administration is clinically relevant, using a mouse allograft model of murine glioma (GL-261 cell line). A magnetic hyperthermia treatment protocol is proposed, in which 25 µg in iron of nanoparticles per mm3 of tumor are administered and exposed to 11 to 15 magnetic sessions during which an alternating magnetic field of 198 kHz and 11 to 31 mT is applied for 30 minutes to attempt reaching temperatures of 43-46 °C. M-PLL are characterized by a larger specific absorption rate (SAR of 40 W/gFe compared to 26 W/gFe for IONPs as measured during the first magnetic session), a lower strength of the applied magnetic field required for reaching a target temperature of 43-46 °C (11 to 27 mT compared with 22 to 31 mT for IONPs), a lower number of mice re-administered (4 compared to 6 for IONPs), a longer residence time within tumours (5 days compared to 1 day for IONPs), and a less scattered distribution in the tumour. M-PLL lead to higher antitumor efficacy with full tumor disappearances achieved in 50% of mice compared to 20% for IONPs. This is ascribed to better ability of M-PLL, at equal iron concentrations, to maintain tumor temperatures at 43-46°C over a longer period of times.

Intracellular pH measured by 31 P-MR-spectroscopy might predict site of progression in recurrent glioblastoma under antiangiogenic therapy.

PURPOSE: In solid tumors, changes in the expression/activity of plasma membrane ion transporters facilitate proton efflux and enable tumor cells to maintain a higher intracellular pH (pHi ), while the microenvironment (pHe ) is commonly more acidic. This supports various tumor-promoting mechanisms. We propose that these changes in pH take place before a magnetic resonance imaging (MRI)-detectable brain tumor recurrence occurs. MATERIALS AND METHODS: We enrolled 66 patients with recurrent glioblastoma, treated with bevacizumab. Patients received a baseline and 8-week follow-up MRI including 1 H/31 P MRSI (spectroscopy) on a 3T clinical scanner, until progressive disease according to Response Assessment in Neuro-Oncology (RANO) criteria occurred. Fourteen patients showed a distant or diffuse tumor recurrence (subsequent tumor) during treatment and were therefore selected for further evaluation. At the site of the subsequent tumor, an area of interest for MRSI voxel selection was retrospectively defined on radiographically unaffected baseline MRI sequences. RESULTS: Before treatment, pHi in the area of interest (subsequent tumor) was significantly higher than pHi of the contralateral normal-appearing tissue (control; P < 0.001). It decreased at the time of best response (P = 0.06), followed by a significant increase at progression (P = 0.03; baseline mean: 7.06, median: 7.068, SD: 0.032; best response mean: 7.044, median: 7.036, SD: 0.025; progression mean: 7.08, median: 7.095, SD 0.035). Until progression, the subsequent tumor was not detectable on standard MRI sequences. The area of existing tumor responded similar, but changes were not significant (decrease P = 0.22; increase P = 0.28). CONCLUSION: Elevated pHi in radiographically unaffected tissue at baseline might precede MRI-detectable progression in patients with recurrent glioblastoma treated with bevacizumab. LEVEL OF EVIDENCE: 2 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2017;46:1200-1208.

Content of endoplasmic reticulum and Golgi complex membranes positively correlates with the proliferative status of brain cells.

Although the molecular and cellular basis of particular events that lead to the biogenesis of membranes in eukaryotic cells has been described in detail, understanding of the intrinsic complexity of the pleiotropic response by which a cell adjusts the overall activity of its endomembrane system to accomplish these requirements is limited. Here we carried out an immunocytochemical and biochemical examination of the content and quality of the endoplasmic reticulum (ER) and Golgi apparatus membranes in two in vivo situations characterized by a phase of active cell proliferation followed by a phase of declination in proliferation (rat brain tissue at early and late developmental stages) or by permanent active proliferation (gliomas and their most malignant manifestation, glioblastomas multiforme). It was found that, in highly proliferative phases of brain development (early embryo brain cells), the content of ER and Golgi apparatus membranes, measured as total lipid phosphorous content, is higher than in adult brain cells. In addition, the concentration of protein markers of ER and Golgi is also higher in early embryo brain cells and in human glioblastoma multiforme cells than in adult rat brain or in nonpathological human brain cells. Results suggest that the amount of endomembranes and the concentration of constituent functional proteins diminish as cells decline in their proliferative activity.

Element distribution is altered in a zone surrounding human glioblastoma multiforme.

Recent data indicate that A(1) adenosine receptor (A(1)AR) density is increased in a zone surrounding human and experimental gliomas. On the contrary, tumor tissue and adjacent brain tissue show low to intermediate A(1)AR densities. In order to assess whether changes in A(1)AR expression are indicating further processes of a chemical reorganization of the peritumoral zone, we investigated element concentrations and distribution patterns of copper and zinc in six human glioblastoma multiforme (GBM) specimens by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). Uranium and lead were used as external standards. Copper and zinc levels were increased in a peritumoral zone corresponding to the region of elevated A(1)AR density. They showed a lower density in the solid tumor in comparison to surrounding brain tissue, although the cellular density was higher within GBM. Our findings suggest that the immediate vicinity of GBM is characterized by increased levels of copper and zinc supporting the view that higher A(1)AR density surrounding GBM is not an isolated alteration of peritumoral tissue but an indicator of complex changes in the vicinity of infiltrative tumors. Further research is needed to explore the pathophysiological consequences of altered peritumoral element distribution.

STI571 (Gleevec) improves tumor growth delay and survival in irradiated mouse models of glioblastoma.

PURPOSE: Glioblastoma multiforme (GBM) is a devastating brain neoplasm that is essentially incurable. Although radiation therapy prolongs survival, GBMs progress within areas of irradiation. Recent studies in invertebrates have shown that STI571 (Gleevec; Novartis, East Hanover, NJ) enhances the cytotoxicity of ionizing radiation. In the present study, the effectiveness of STI571 in combination with radiation was studied in mouse models of GBM. METHODS AND MATERIALS: Murine GL261 and human D54 GBM cell lines formed tumors in brains and hind limbs of C57BL6 and nude mice, respectively. GL261 and D54 cells were treated with 5 micromol/L of STI571 for 1 h and/or irradiated with 3 Gy. Protein was analyzed by Western immunoblots probed with antibodies to caspase 3, cleaved caspase 3, phospho-Akt, Akt, and platelet-derived growth factor receptor (PDGFR) alpha and beta. Tumor volumes were assessed in mice bearing GL261 or D54 tumors treated with 21 Gy administered in seven fractionated doses. Histologic sections from STI571-treated mice were stained with phospho-Akt and phospho-PDGFR beta antibodies. Kaplan-Meier survival curves were used to study the response of mice bearing intracranial implants of GL261. RESULTS: STI571 penetrated the blood-brain barrier, which resulted in a reduction in phospho-PDGFR in GBM. STI571-induced apoptosis in GBM was significantly enhanced by irradiation. STI571 combined with irradiation induced caspase 3 cleavage in GBM cells. Glioblastoma multiforme response to therapy correlated with an increase in tumor growth delay and survival when STI571 was administered in conjunction with daily irradiation. CONCLUSION: These findings suggest that STI571 has the potential to augment radiotherapy and thereby improve median survival.

Spectromicroscope for the PHotoelectron Imaging of Nanostructures with X-rays (SPHINX): performance in biology, medicine and geology.

Several X-ray PhotoElectron Emission spectroMicroscopes (X-PEEMs) exist around the world at this time. We present recent performance and resolution tests of one of them, the Spectromicroscope for PHotoelectron Imaging of Nanostructures with X-rays (SPHINX) X-PEEM, installed at the University of Wisconsin Synchrotron Radiation Center. With this state-of-the-art instrument we demonstrate chemical analysis capabilities on conducting and insulating specimens of diverse interests, and an unprecedented lateral resolution of 10 nm with monochromatic X-rays and 7.2 nm with ultraviolet illumination.

In vivo evaluation of the boronated porphyrin TABP-1 in U-87 MG intracerebral human glioblastoma xenografts.

Boron neutron capture therapy (BNCT) is an adjuvant therapy that has the potential to control local tumor growth. A selective delivery of sufficient amounts of boron to individual tumor cells, compared to surrounding normal tissues, is the key for successful BNCT. We have designed and synthesized a new highly water-soluble boronated porphyrin, TABP-1, as a possible BNCT agent. When we injected the maximum tolerated dose (MTD: 15 mg/kg) of TABP-1 systemically into the tail vein of athymic rats bearing intracerebral (i.c.) human glioblastoma U-87 MG xenografts, the compound accumulated preferentially in brain tumors compared to normal brain; however, the level of boron in the tumors was less than the 30 microg/g of tissue that is generally considered necessary for BNCT. We next investigated whether convection-enhanced delivery (CED) could improve the boron distribution. The compound was administered directly into i.c. tumors using an osmotic minipump attached to a brain-infusion cannula. TABP-1 doses from 0.25 to 1.0 mg infused locally over 24 h produced tumor boron concentrations greater than those obtained by systemic administration at the MTD. For example, CED administration of 0.5 mg of TABP-1 produced a tumor boron level of 65.4 microg/g of tumor, whereas the serum level was only 0.41 microg/g (tumor to serum ratio of approximately 160:1). CED also produced relatively high tumor to normal brain ratios of approximately 5:1 for ipsilateral brain and approximately 26:1 for contralateral brain tissues at the 0.5 mg dose. Thus, we may be able to achieve therapeutic BNCT efficacy with minimal systemic toxicity or radiation-induced damage to normal tissue by administering TABP-1 using CED.

Discrimination of brain abscess and cystic tumor by in vivo proton magnetic resonance spectroscopy.

Proton magnetic resonance (MR) spectroscopy was evaluated for the differentiation of brain abscesses and cystic brain tumors. Proton MR spectroscopy was performed in vivo in two patients with brain abscess and eight patients with various cystic brain tumors (anaplastic astrocytoma, glioblastoma, and metastatic brain tumor). MR imaging with contrast medium demonstrated ring-like enhanced mass lesions in all patients. The various resonance peaks in proton MR spectra were assigned to metabolites according to chemical shifts. Treatment of the cystic brain lesions was based on the information from proton MR spectroscopy. Aspirated pus from one patient with brain abscess was examined using ex vivo proton MR spectroscopy. The in vivo spectra of brain abscess contained resonance peaks attributed to acetate, lactate, alanine, amino acids, and lipids in both cases, and an additional peak of succinate in one case. In vivo spectra of the neoplasms contained resonance peaks corresponding to lactate, lipids, choline, creatine, and N-acetyl aspartate. Proton MR spectroscopy is useful for discriminating brain abscess from cystic tumors with similar neuroimaging appearance, which is very important for determining the treatment strategy.

Characterization of lipids from human brain tissues by multinuclear magnetic resonance spectroscopy.

Multinuclear ((1)H, (13)C, and (31)P) magnetic resonance spectroscopy are applied to the biochemical characterization of the total lipid fraction of healthy and neoplastic human brain tissues. Lipid extracts from normal brains, glioblastomas, anaplastic oligodendrogliomas, oligodendrogliomas, and meningiomas are examined. Moreover, the unknown liquid content of a cyst adjacent to a meningioma is analyzed. Two biopsies from glioblastomas are directly studied by (1)H-NMR without any treatment (ex vivo NMR). The (1)H- and (13)C-NMR analysis allows full characterization of the lipid component of the cerebral tissues. In particular, the presence of cholesteryl esters and triglycerides in the extracts of high grade tumors is correlated to the vascular proliferation degree, which is different from normal brain tissue and low grade neoplasms. The (31)P spectra show that phosphatidylcholine is the prominent phospholipid and its relative amount, which is higher in gliomas, is correlated to the low grade of differentiation of tumor cells and an altered membrane turnover. The ex vivo (1)H-NMR data on the glioblastoma samples show the presence of mobile lipids that are correlated to cell necrotic phenomena. Our data allow a direct correlation between biochemical results obtained by NMR and the histopathological factors (vascular and cell proliferations, differentiation, and necrosis) that are prominent in determining brain tumor grading.

Isolation and identification of cDNA fragments and full-length cDNA differentially expressed in human glioblastoma cell line BT-325 versus all-trans retinoic acid induction .

OBJECTIVE: To investigate the differentiation process of the human glioblastoma cells. METHODS: Differential display reverse transcribed-PCR (DDRT-PCR) was used to isolate the genes differentially expressed in control and all-trans retinoic acid treated human glioblastoma cell line BT-325. Routine method of cDNA library screening was performed to clone full-length cDNA. RESULTS: Thirty-six RT-PCR reactions were performed and 64 differentially expressed fragments were recovered, amplified and cloned. Of them, 46 ESTs were sequenced and delivered into the GenBank. The homology comparison using BLAST algorithm revealed that 22ESTs are highly homologous with the known genes and many of them play important roles in the cell differentiation progress. A dot-blot hybridization was conducted to certify the differentiation expression. The result showed that 27 EST clones are expressed at different level in control and all-trans retinoic acid treated BT-325 cells. A full-length cDNA was cloned using the EST-HGBB098. CONCLUSION: DDRT-PCR was a simple and effective method to serially analyze the differentially expressed genes.

Effect of hyperthermia on intracellular pH in human U-87 MG glioblastoma cells.

The effect of hyperthermia at 43 degrees C on intracellular pH (pHi) in human U-87 MG glioblastoma cells was studied by using the fluorescent probe 2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein-pentaacetoxymethyl ester. The presence of Na+/H+ antiporter activity in the cells were demonstrated by the Na(+)-dependent increase in intracellular pH (pHi) after cellular acidification in the absence of HCO3-. Hyperthermia at 43 degrees C caused significant decrease in pHi. The acidification was readily reversible by cooling the cells back down to 37 degrees C. The pHi change was inhibited by the addition of 1 mM amiloride in the incubation medium. Amiloride and hyperthermia exhibited a synergistic effect in suppressing thymidine incorporation into the cells.

Timing of hypertonic glucose and thermochemotherapy with 1-(4-amino-2-methylpyrimidine-5-yl) methyl-3-(2-chloroethyl)-3-nitrosourea (ACNU) in the BT4An rat glioma: relation to intratumoral pH reduction and circulatory changes after glucose supply.

PURPOSE: Intraperitoneal hypertonic glucose has previously been shown to induce hyperglycemia, hemo-concentration, and to influence systemic and tumor circulation, and, thus, enhance the effect of thermochemotherapy with 1-(4-amino-2-methylpyrimidine-5-yl)methyl-3-(2-chloroethyl)-3-nitrosoure a (ACNU) and 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU). However, the optimal timing and the precise mechanisms responsible are not known. The effect of different time intervals between glucose load and thermochemotherapy with ACNU in the treatment of BT4An tumors, therefore, was investigated. Changes of serum glucose (Se-glucose), hemoglobin, systemic circulation parameters, tumor pH, and tumor temperature, induced by intraperitoneal glucose and/or hyperthermia, were measured to assess their effect on tumor growth. METHODS AND MATERIALS: (a): Inbred BD IX rats with BT4An tumors on the hind leg were treated with ACNU 7 mg/kg intravenously just before waterbath hyperthermia, and intraperitoneal hypertonic glucose (6 g/kg) at different time intervals before (240-0 min) or immediately after thermochemotherapy. (b): Intratumoral pH and temperature were measured at different intervals after intraperitoneal glucose, and during hyperthermia with or without previous glucose. (c): Hemoglobin, hematocrit, and Se-glucose were measured at different times after intraperitoneal glucose. (d): Mean arterial pressure, pulse pressure, and heart rate were measured for 120 min after intraperitoneal glucose. RESULTS: (a): The number of tumor controls and the growth delay was greatest with glucose 45 min before thermochemotherapy, and least with a time interval of 240 min. Glucose after thermochemotherapy delayed tumor growth. (b): After intraperitoneal glucose alone, intratumoral pH decreased gradually from 6.76 to 5.86 after 240 min. Hyperthermia 120 min after glucose induced a rapid further pH drop, while hyperthermia alone had no significant influence on pH. Intratumoral temperature was higher during hyperthermia in animals given glucose. (c): A substantial rise of Se-glucose and hemoglobin developed. The hemoconcentration was maintained also after reduction of Se-glucose towards normal values. (d): An initial tachycardia, and a reduction of the mean arterial pressure of about 10% 5-45 min after was measured. CONCLUSION: The data indicate that a complex interaction between gradually reduced tumor pH, hyperglycemia, hemoconcentration, and reduced tumor blood flow, and not a breakdown of systemic circulation, is responsible for the effect of intraperitoneal glucose on thermochemotherapy with ACNU. Interestingly, enhancement of thermochemotherapy effect was also seen when intraperitoneal glucose was given after heat and ACNU.

Reversal of chemoresistance in malignant gliomas by calcium antagonists: correlation with the expression of multidrug-resistant p-glycoprotein.

Resistance to multiple drugs is often observed in malignant gliomas. The authors used a microtiter tetrazolium test to analyze primary in vitro chemoresistance and chemosensitivity of 15 early cultures of human malignant glioma exposed to 50 micrograms/ml (1,4-amino-2-methyl-5-pyrimidinyl)-methyl-3-(2-chloroethyl)-3-nitrosoure a (ACNU), 50 micrograms/ml cisplatin, 1 microgram/ml vincristine, or combinations of these chemotherapeutic agents. Primary chemoresistance was observed in 87% of tumors for ACNU, in 87% for cisplatin, and in 83% for vincristine. All tumors were examined for expression of multidrug-resistant p-glycoprotein, a transport protein of 170,000 D, by means of immunohistochemical staining with the JSB-1 antibody on paraffinized tumor sections. Eight of 15 specimens (53%) showed positive staining for the monoclonal antibody. Primary chemoresistance was overcome by addition of the calcium antagonists verapamil or nimodipine to the cultures if the original tumor expressed p-glycoprotein (p < 0.01 for verapamil, p < 0.05 for nimodipine). In tumors not expressing p-glycoprotein, addition of calcium antagonists to the cell cultures did not influence primary chemoresistance. It is concluded from these data that addition of calcium antagonists to the adjuvant chemotherapy of malignant gliomas might overcome primary chemoresistance in tumors expressing the multidrug-resistant phenotype.

Development and reversion of methionine dependence in a human glioma cell line: relation to homocysteine remethylation and cobalamin status.

We investigated the biochemical changes which accompanied the development and reversion of methionine dependence in a human glioma cell line GaMg. This cell line attained a higher proliferation rate and more malignant morphology with increasing passages in vitro. Early passages (P10, P25, and P45) were able to grow in a methionine-deficient medium supplemented with homocysteine (Met-Hcy+), while a later passage (P60) had lost this ability, i.e., it had become methionine-dependent. From P60 cells, a methionine-independent revertant (P60R) was established by exposing the cells to 5-aza-2-deoxycytidine, followed by culture in a Met-Hcy+ medium. In these genetically related cell lines, we investigated homocysteine remethylation and the functional state of cobalamin-dependent methionine synthase, the enzyme responsible for remethylation of homocysteine to methionine. The methionine synthase activity in cell extracts was similar in all cell sublines. Intact cell methionine biosynthesis and nitrous oxide-dependent homocysteine export reflect homocysteine remethylation in cells cultured in a Met-Hcy+ and methionine-containing (Met+Hcy-) medium, respectively. Both of these parameters, as well as the cellular content of the substrate 5-methyltetrahydrofolate, and the cofactor methylcobalamin, in addition to adenosylcobalamin, were high in P10, declined progressively in P45 and P60, and were restored in P60R. P25 cells had some unique features among the methionine-independent phenotypes because both homocysteine remethylation and the level of 5-methyltetrahydrofolate were low in Met+Hcy- medium. The maximal homocysteine export rate in the presence of nitrous oxide, which reflects the overall transmethylation rate, was high in P60 and even higher in P60R compared to the lower passages. The basis for development of methionine dependence during culture of this glioma cell line seems related to the combined effects of reduced methionine biosynthesis and an increased overall transmethylation rate. The single parameter which most closely correlated to the ability to use homocysteine for growth was methylcobalamin. These data support a model for methionine dependence, which implies impaired provision of cobalamin to methionine synthase.