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PubMedDate not supplied

Retrovirus-mediated gene therapy of experimental brain neoplasms using the herpes simplex virus-thymidine kinase/ganciclovir paradigm.

Recent results in experimental brain tumors indicate that transfer of sensitizing genes to tumor cells in vivo with subsequent drug treatment can reduce tumor masses and prolong the survival of rodents. In the present study, the 9L rat gliosarcoma model was used to evaluate the therapeutic effectiveness of the herpes simplex virus-thymidine kinase (HSV-tk) gene, delivered by a retrovirus vector, against tumor cells in the rat brain after systemic application of the nucleoside analogue ganciclovir (GCV). The HSV-tk gene was inserted into a retroviral vector (pMFG), which was produced using the amphotropic packaging cell line CRIP-MFG-S-HSV-TK. Packaging cells were implanted into established 9L tumors in the brains of syngeneic rats to effect gene delivery to tumor cells, followed by intraperitoneal GCV injections. Treated animals survived significantly longer (more than twice as long) than did the control groups. Brains from GCV-treated and nontreated animals were examined immunohistochemically at different time intervals after grafting of CRIP-MFG-S-HSV-TK cells and GCV treatment. Tumors in GCV-treated animals were significantly smaller as compared with nontreated animals at all time points. Sections stained immunohistochemically for HSV-TK confirmed gene transfer to tumor cells, which could be distinguished from packaging cells by different morphology and immunohistochemical staining for the retroviral envelope protein gp70. Approximately 45% of the cells in tumors implanted with CRIP-MFG-S-HSV-TK cells, but not treated with GCV, showed immunocytochemical staining for HSV-TK, demonstrating a high-efficiency of retrovirus-mediated gene transfer. Tumors in rats treated with packaging cells and GCV showed only 9% HSV-TK-positive cells after treatment, indicating that most cells expressing the HSV-tk gene were killed. The success of this therapeutic modality in experimental animals depends in large parts on the high efficiency of gene delivery and on the immune response against tumor cells.

Animals↗
PubMed1996

Ion microscopy imaging of 10B from p-boronophenylalanine in a brain tumor model for boron neutron capture therapy.

Boron neutron capture therapy (BNCT), a binary treatment modality that can potentially irradiate tumor tissue within cellular dimensions, is critically dependent on the preferential delivery of 10B to individual neoplastic cells. In this study, ion microscopy was used to quantitatively evaluate the selectivity of p-boronophenylalanine-fructose (BPA-F) in the rat 9L gliosarcoma brain tumor model. With a spatial resolution of approximately 0.5 microm, ion microscopy images show that BPA-F delivers 3.5 times more boron to the main tumor mass [99 +/- 36 microg/g tissue (mean +/- SD)] than to the contiguous normal brain (27 +/- 12 microg/g tissue). A similar, but lower, accumulation was observed away from the main tumor mass in small clusters of neoplastic cells (47 +/- 15 microg/g tissue) invading the surrounding brain (16 +/- 8 microg/g tissue). These findings establish for the first time the selectivity of BPA-F to the neoplastic cells invading the normal brain and provide a much-needed baseline measurement of the distribution of a clinically approved BNCT drug. Given the propensity for malignant brain tumors to infiltrate the surrounding normal brain, these observations have particular significance for clinical trials of BNCT for human glioblastoma multiforme using the drug BPA-F.

Animals↗
PubMed1997

Potentiation of cytochrome P450/cyclophosphamide-based cancer gene therapy by coexpression of the P450 reductase gene.

Intratumoral expression of cytochrome P450 2B1 sensitizes tumor cells to the cytotoxic action of the alkylating agent prodrug cyclophosphamide (CPA) and provides a novel strategy for cancer gene therapy that may enhance the selectivity and the effectiveness of this class of antitumor drugs [L. Chen and D. J. Waxman, Cancer Res., 55: 581-589, 1995]. P450-catalyzed drug metabolism is obligatorily dependent on electron input from the flavoenzyme NADPH-P450 reductase (RED), which is widely expressed in many cell types, including tumor cells. Here, we investigate the potential utility of combining RED gene transfer with CPA-based P450 gene therapy. Rat 9L gliosarcoma cells stably expressing either basal or elevated (up to 10-fold increase) levels of RED, in the presence or absence of P450 2B1, were selected and characterized. RED overexpression substantially increased the sensitivity of these cells to CPA, but only when combined with P450 2B1 expression. An enhanced cytotoxic response was also obtained when recombinant adenovirus encoding P450 2B1 was used to deliver the P450 gene to RED-overexpressing tumor cells. CPA cytotoxicity was substantially decreased by the RED inhibitor diphenyleneiodonium chloride or by the P450 inhibitor metyrapone, providing evidence of its dependence on the catalytic contributions of both protein components of the P450 metabolic pathway. Conditioned media from P450 2B1-expressing and RED-overexpressing tumor cells treated with CPA exhibited increased formation of the primary 4-hydroxy metabolite and greater cell contact-independent bystander cytotoxic potential compared to tumor cells containing P450 2B1 and basal levels of RED. Evaluation of the impact of P450/RED combination gene therapy using a s.c. solid tumor model/tumor excision assay revealed a dramatic 50-100-fold increase in tumor cell kill in vivo over that provided by liver drug activation alone. These findings establish the importance of endogenous RED levels as a determinant of the sensitivity of tumor cells to CPA/P450 gene therapy and demonstrate the striking therapeutic effectiveness of an anticancer prodrug activation strategy based on the combination of a cytochrome P450 gene with the gene encoding RED.

Adenoviridae↗
PubMed1998

Retroviral transfer of human cytochrome P450 genes for oxazaphosphorine-based cancer gene therapy.

Cyclophosphamide (CPA) and ifosfamide (IFA) are widely used anticancer prodrugs that are bioactivated in the liver by specific cytochrome P450 enzymes (CYPs). The therapeutic activity of these antitumor agents can be compromised by a low therapeutic index that is, in part, due to the systemic distribution of activated drug metabolites. Here, recombinant retroviruses were used to deliver six different CPA- or IFA-metabolizing human CYP genes to 9L gliosarcoma cells: 2B6, 2C8, 2C9, 2C18 (Met385 and Thr385 alleles), 2C19, and 3A4. Intratumoral cytochrome P450 expression conferred substantial sensitivity to CPA cytotoxicity, with the most dramatic effects seen with CYP2B6. Strong CPA chemosensitivity was also seen following transduction of CYP2C18-Met, despite a very low level of CYP protein expression (>60-fold lower than that of 2B6). In contrast to CPA, the cytotoxicity of IFA was greatest toward tumor cells transduced with CYP3A4, followed by CYPs 2B6 and 2C18-Met. A substantial further increase in chemosensitivity was achieved upon transduction of 2B6 or 2C18-Met-expressing tumor cells with P450 reductase, which provided for more efficient intratumoral prodrug activation and cytotoxicity at lower drug concentrations. With 2B6- plus P450 reductase-transduced tumor cells, CPA but not IFA conferred a strong cell contact-independent bystander cytotoxic effect on non-P450-expressing 9L cells. CPA treatment of tumors that were transduced with 2B6 or 2C18-Met together with P450 reductase and were grown s.c. in immunodeficient mice resulted in a large enhancement of the liver P450-dependent antitumor effect seen with control 9L tumors, with no apparent increase in host toxicity (growth delay of >25-50 days in P450-expressing tumors versus approximately 5-6 days without P450). CYP2B6 plus P450 reductase and CYP2C18-Met plus P450 reductase thus appear to be excellent gene combinations for use with CPA in P450/prodrug activation-based cancer gene therapy.

Animals↗
PubMed1997

Pronounced antitumor effects and tumor radiosensitization of double suicide gene therapy.

The efficacy of HSV-1 thymidine kinase (TK) and Escherichia coli cytosine deaminase (CD) suicide gene therapies as cancer treatments are currently being examined in humans. We demonstrated previously that compared to single suicide gene therapy, greater levels of targeted cytotoxicity and radiosensitization can be achieved in vitro by genetically modifying tumor cells to express CD and HSV-1 TK concomitantly, as a fusion protein. In the present study, the efficacy of the combined double suicide gene therapy/radiotherapy approach was examined in vivo. Nude mice were injected either s.c. or i.m. with 9L gliosarcoma cells expressing an E. coli CD/HSV-1 TK fusion gene. Double suicide gene therapy using 5-fluorocytosine (500 mg/kg) and ganciclovir (30 mg/kg) proved to be markedly better at delaying tumor growth and achieving a tumor cure than single suicide gene therapy, which used 5-fluorocytosine or ganciclovir administered independently. Importantly, double suicide gene therapy was highly effective against large experimental tumors (>2 cm3), reducing tumor volume an average of 99% and producing a 40% tumor cure. Moreover, double suicide gene therapy profoundly potentiated the antitumor effects of radiation. The results indicate that double suicide gene therapy, particularly when coupled with radiotherapy, may represent a highly effective means of eradicating tumors.

Animals↗
PubMed1986

Second malignant neoplasm in treated Hodgkin's disease. Report of a patient and scope of the problem.

The condition of a 6-year-old boy was diagnosed as mixed-cellularity Hodgkin's disease that involved the right side of the neck. Five years after the completion of radiation therapy for the involved area, followed by six courses of chemotherapy with mechlorethamine hydrochloride (nitrogen mustard), vincristine sulfate, procarbazine hydrochloride, and prednisone, he developed cerebral gliosarcoma. Numerous second malignant neoplasms have been reported in adults following treatment for Hodgkin's disease; however, the sequence of events in our patient is a new finding that has not, to our knowledge, been reported previously. While the second malignant tumor may have been induced by prior treatment, direct evidence is lacking.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1979

Reactive glioma in intracranial sarcoma: a form of mixed sarcoma and glioma ("sarcoglioma"): report of eight cases.

The clinicopathologic features of eight new cases of combined intracranial sarcoma and glioma are described. This type of mixed cerebral tumor is histologically characterized by a peripheral distribution of the gliomatous elements in relation to a more centrally situated meningeal or intracerebral sarcoma, and by the frequent presence of gradual transitions from reactive to frankly neoplastic astrocytes. In six of the eight cases, the additional development of either infiltrating astrocytoma or frank glioblastoma in the adjacent brain was demonstrated; this was interpreted as a further expression of malignant glial reaction. It is suggested that these tumors be termed "sarcogliomas" to distinguish them from the type of mixed glioma and sarcoma that has recently been redesignated "gliosarcoma."

Adolescent↗
PubMed1984

Sarcoma arising in metastatic carcinoma in the brain. A second instance.

A second instance in which a carcinoma metastatic to the brain has induced the formation of a sarcoma in the associated cerebral blood vessels, is reported. This is analogous to the more common gliosarcoma, a tumor in which a primary glioma, most often anaplastic astrocytoma (glioblastoma multiforme), has induced the formation of a similar sarcoma, with both neoplastic tissues in the same tumor mass. The formation of the sarcoma is attributed to a neoplastic change in the markedly hyperplastic endothelial cells of the cerebral blood vessels that are very commonly found with anaplastic astrocytomas and are often found in relation to metastatic carcinoma. The progression of hyperplasia to neoplasia has long been considered of oncogenetic significance, and in this specific circumstance, appears to be due to some factor or substance which passes from the carcinoma cells to the cerebral vessels.

Astrocytoma↗
PubMed1991

Mixed glioblastoma multiforme and sarcoma. A clinicopathologic study of 26 radiation therapy oncology group cases.

Twenty-six cases are reported of gliosarcoma (GS) retrieved from a series of 1479 glioblastomas (GBM) that were part of five consecutive, randomized Phase II or III malignant glioma protocols initiated by the Radiation Therapy Oncology Group between 1974 and 1983. The clinicopathologic features of these 26 cases, including actuarial survival times, were compared with the remaining 1453 GBM. The minimal qualitative and quantitative histologic criteria required to diagnose GS are presented. In most cases the sarcomatous component was a malignant fibrous histiocytoma; a minority were fibrosarcoma. No significant differences between GS and GBM were found with regard to age, sex, pretreatment Karnofsky performance status, tumor location, size, median survival (8.3 and 9.6 months, respectively), and actuarial survival. None of the treatment regimens, which included various combinations of radiation therapy and chemotherapy, improved the survival of GS over GBM. Selective involvement of the temporal lobe by GS was not found, and the frequency of GS was determined to be only 1.8% of all GBM.

Adult↗
PubMed2001

A phase III study of radiation therapy plus carmustine with or without recombinant interferon-alpha in the treatment of patients with newly diagnosed high-grade glioma.

BACKGROUND: The current study was conducted to determine whether the addition of interferon-alpha (IFN-alpha) to treatment with radiation therapy and carmustine (BCNU) improves time to disease progression or overall survival in patients with high-grade glioma. METHODS: Patients with anaplastic astrocytoma, anaplastic oligoastrocytoma, glioblastoma multiforme, or gliosarcoma received radiation therapy plus BCNU as initial therapy. Subsequently, patients without tumor progression at the completion of radiation therapy were stratified by age, extent of surgery, tumor grade and histology, Eastern Cooperative Oncology Group performance status, and treating institution, and then were randomly assigned to receive either BCNU alone (200 mg/m(2) on Day 1) or BCNU (150 mg/m(2) on Day 3) plus IFN--alpha (12 million U/m(2) on Days 1-3, Weeks 1, 3, and 5) every 7 weeks for a maximum of 6 cycles. RESULTS: Of the 383 patients enrolled in the study, 275 eligible patients were randomized. There was no significant difference with regard to time to disease progression or overall survival between the two groups. Patients receiving IFN-alpha experienced more fever, chills, myalgias, and neurocortical symptoms including somnolence, confusion, and exacerbation of neurologic deficits. Cox multivariate regression models confirmed known favorable prognostic variables including younger age, Grade 3 tumor (according to World Health Organization criteria), and greater extent of surgery. Cox and classification and regression tree analysis models also demonstrated that a normal baseline Folstein mini-mental status examination (MMSE) score was associated with better prognosis. CONCLUSIONS: IFN-alpha does not appear to improve time to disease progression or overall survival in patients with high-grade glioma and appears to add significantly to toxicity. The baseline MMSE score may serve as an independent prognostic factor and warrants further investigation.

Adult↗
PubMed2001

Long-term stabilization in patients with malignant glioma after treatment with liposomal doxorubicin.

BACKGROUND: Resistance to chemotherapeutic agents and poor blood-brain barrier penetration are major limitations in the treatment of malignant glioma. To improve drug delivery across the blood-brain barrier, the authors used doxorubicin as liposomal encapsulated formulation (Caelyx, Scheringh-Plough, Munich, Germany) in therapy of recurrent malignant glioma. METHODS: Fifteen patients with recurrent high-grade gliomas were included in the study. Of these, 13 patients could be evaluated, including 6 patients with glioblastoma, 1 patient with gliosarcoma and 6 patients with anaplastic astrocytoma. The treatment consisted of liposomal doxorubicin (20 mg/m(2)), applied intravenously every 2 weeks. RESULTS: Stabilization of the disease was observed in 54% (7 of 13) of patients. Partial response and complete response (CR) were not observed. Median time-to-progression was 11 weeks. Progression free survival at 12 months was 15%. Median overall survival (OS) after doxorubicin therapy was 40.0 weeks, whereas the median OS after diagnosis reached 20.0 months (87.0 weeks). Doxorubicin was well tolerated, with main side effects being palmoplantar erythrodysesthesia occurring in 38% and myelotoxicity (World Health Organization Grade 3-4) in 31% of the patients. CONCLUSIONS: Doxorubicin has been shown to be a safe treatment with moderate activity that may lead to long-term stabilization in recurrent high-grade glioma patients. Of note, median OS after all and after initiation of recurrence therapy was prolonged in comparison with the OS in other Phase II studies, as recently described by Wong et al. (Wong ET, Hess KR, Gleason MJ, Jaeckle KA, Kyritsis AP, Prados MD, et al. Outcomes and prognostic factors in recurrent glioma patients enrolled onto phase II clinical trials. J Clin Oncol 1999;17:2572.).

Adult↗
PubMed2000

Studies on nerve cell affinity of chitosan-derived materials.

Reparation of the central nervous system (CNS) is important because when it is impaired its recovery is difficult and concomitant malfunction of other parts of body occurs. In our previous studies, chitosan was found to be a good material supporting nerve repair. The purpose of this article was to study the ability of chitosan and some chitosan-derived materials to facilitate the growth of nerve cells. Those materials were chitosan, glutaraldehyde-crosslinked chitosan, glutaraldehyde-crosslinked chitosan-gelatin conjugate, a chitosan-gelatin mixture, chitosan coated with polylysine (CAP), and a chitosan-polylysine mixture (CPL). Gelatin and polylysine were used as controls. After nerve cells (gliosarcoma cells and normal cerebral cells) were grown on those materials, their attachment, spread, and growth were observed. The adsorption of some extracellular matrix molecules such as laminin and fibronectin on the materials and the role the molecules play in nerve cell attachment and spreading were also studied by enzyme-linked immunosorbent assay and MTT method. We found that both CAP and CPL have excellent nerve cell affinity, defined as the ability to promote nerve cell to grow and function normally. Those two materials may be promising for the repair of the nervous system. Materials precoated with laminin, fibronectin, and serum were analyzed for their nerve cell affinity. Results suggest that after being precoated with laminin and fibronectin solution or serum, all material have better nerve cell affinity.

Animals↗
PubMed1992

Prognostic value of cytogenetic analysis in human cerebral astrocytomas.

Cytogenetic analysis has become an important part of the diagnostic evaluation of most hematological neoplasms. However, there is limited information on the value of cytogenetic analysis in most solid tumors, including cerebral astrocytomas. This report summarizes a prospective cytogenetic study of 99 human cerebral astrocytomas, 16 mixed oligoastrocytomas, and 2 gliosarcomas. The cytogenetic procedure involved in situ culture and robotic harvesting techniques. Correlative clinical and survival data were available on all patients. We successfully cultured and obtained suitable metaphases in 107 of the 117 tumors. One or more chromosomally abnormal clones were observed in 72 tumors, and nonclonal or normal karyotypes were observed in 35 tumors. In a multivariate analysis, survival time was significantly better in patients whose tumors had normal or nonclonal karyotypes on cytogenetic analyses than in those whose tumors had clonal abnormalities (p = 0.0071). Our study demonstrates that cytogenetic analysis provides independent prognostic information in patients with cerebral astrocytomas.

Astrocytoma↗
PubMed2003

Phase I study of temozolomide and escalating doses of oral etoposide for adults with recurrent malignant glioma.

BACKGROUND: Although temozolomide is active against recurrent malignant glioma, responses in many patients are modest and short-lived. Temozolomide may prove more effective in combination with other agents. Therefore, combination oral chemotherapy for these patients is a particularly attractive approach. METHODS: The authors conducted a Phase I study of temozolomide in combination with escalating doses of oral etoposide (VP-16) to determine the maximum tolerated doses of these two agents when given together. The temozolomide dose was fixed at 150 mg/m(2) per day on Days 1-5. The oral VP-16 was escalated in cohorts of 3 to 6 patients by numbers of days of VP-16 administered: 50 mg/m(2) per day, Days 1-5 (dose level 1), Days 1-8 (dose level 2), Days 1-12 (dose level 3), Days 1-16 (dose level 4), and Days 1-20 (dose level 5). Therapy was given in 28-day cycles. RESULTS: Of the 29 patients enrolled, 26 were fully evaluable and 3 were partially evaluable for toxicity. The 29 patients received a total of 92 cycles. The median age of the patients was 49 years (range, 28-76 years). Diagnoses included glioblastoma (n = 19), gliosarcoma (n = 3), anaplastic astrocytoma (n = 5), and anaplastic oligoastrocytoma (n = 2). The median time from diagnosis to disease recurrence was 8 months (3-188 months). Twenty patients were treated at the first disease recurrence, seven at the second, and two at the third. Twenty-four patients (83%) were receiving anticonvulsants and 24 were receiving dexamethasone. All patients had received previous radiation, and 25 of 29 had been treated with chemotherapy previously. Of the 3 patients at dose level 1, none had dose-limiting toxicity (DLT). Of the 6 patients at dose level 2, 1 patient had DLT: Grade 3 thrombocytopenia resulting in a > 2-week delay in starting the next cycle of chemotherapy. Of the 6 patients at dose level 3, 1 patient had DLT: death due to pneumonia. There were 2 DLTs in the 7 patients at dose level 4: fever, neutropenia, and herpes zoster infection in 1 patient and death due to pneumonia in another. Seven patients had been started at dose level 5 when DLT was established at dose level 4: of the 5 fully evaluable and 2 partially evaluable patients at dose level 5, there was no DLT. CONCLUSIONS: The maximum tolerated dose of temozolomide and oral VP-16 in this heavily treated group of patients with recurrent malignant glioma is temozolomide 150 mg/m(2) per day for 5 days and oral VP-16 50 mg/m(2) per day for 12 days.

Administration, Oral↗
PubMed1991

Molecular and cytogenetic analysis of tumors in von Recklinghausen neurofibromatosis.

Von Recklinghausen neurofibromatosis (NF1) is a common autosomal dominant disorder mapped to 17q11.2 and typically characterized by the occurrence of neural crest-derived tumors. The gene has recently been cloned using reverse genetics or "positional cloning" approaches. Its function, however, remains unknown. We have performed cytogenetic and molecular analyses on 9 malignant tumors from NF1 patients to look for loss of alleles or chromosome rearrangements involving chromosome 17 to test the hypothesis that the NF1 gene acts as a recessive "tumor suppressor" gene. Loss of alleles on this chromosome was detected for 3 of 9 malignant tumors. Two peripheral nerve sheath tumors showed allele loss at informative loci on both the long and short arms of chromosome 17. In contrast, a glioblastoma with focal gliosarcoma showed loss of heterozygosity on the short arm of chromosome 17 only, and not at loci on the long arm. One nerve sheath tumor was previously shown by direct sequence analysis to have a point mutation at the TP53 locus at 17p13. These data support a role for the TP53 gene or other genes on the short arm of chromosome 17 in at least some malignancies in NF1. Six other neurofibrosarcomas showed no allele loss at informative loci on chromosome 17. Cytogenetic analysis was performed on 7 tumors, including 2 with allele loss. The two tumors with allele loss showed abnormal karyotypes while all others were normal. Southern blot and pulsed-field gel analysis using probes within or closely linked to the NF1 locus detected no gross deletions or rearrangements in the tumors studied.(ABSTRACT TRUNCATED AT 250 WORDS)

Alleles↗
PubMed2003

The effect of brain tumor angiogenesis on the in vivo relationship between the gradient-echo relaxation rate change (DeltaR2*) and contrast agent (MION) dose.

PURPOSE: To determine in vivo if the susceptibility calibration factor for gradient-echo imaging (k(G)), which characterizes the relationship between the tissue T2* relaxation rate change (DeltaR2*) and tissue contrast agent concentration, is independent of tissue type and condition; in addition, to assess the consequences of such an assumption on the use of relative cerebral blood volume (rCBV) measurements as a direct index of tumor angiogenesis. MATERIALS AND METHODS: The DeltaR2* was measured as a function of monocrystalline iron oxide nanoparticles (MION) contrast agent dose in a rat brain tumor (9L gliosarcoma) model, the blood volume fraction independently measured, and k(G) calculated and compared for the normal gray matter, normal white matter, tumor, and contralateral brain. RESULTS: The k(G) was found to be the same for gray and white matter (P = 0.53), but statistically different for tumor compared to contralateral brain (P = 0.005) with k(G(Tumor) ) < k(G(Brain) ) CONCLUSION: The gradient-echo calibration factor, k(G), is the same for brain gray and white matter, but not the same for brain and tumor tissue. This difference may be attributed to the grossly different vascular morphology of tumors, dueto tumor angiogenesis, compared to normal brain and/or possibly differing blood rheological factors such as hematocrit. Consequently, the sensitivity to blood volume differences between tumor and normal brain tissue may be lessened when using gradient-echo susceptibility contrast agent methods.

Animals↗
PubMedDate not supplied

Boronated metalloporphyrins: a novel approach to the diagnosis and treatment of cancer using contrast-enhanced MR imaging and neutron capture therapy.

Porphyrins are a unique class of metal chelating agents that have shown specific affinity for neoplasms. The water-soluble free-base derivative, tetrakiscarborane carboxylate ester of 2,4-(alpha,beta-dihydroxyethyl) deuteroporphyrin IX (BOPP), an agent designed for neutron capture therapy, has previously demonstrated selective localization and retention in a C6 murine glioma. In the present work, the authors demonstrate that the manganese chelate of BOPP also selectively localizes in a rat 9L gliosarcoma and preferentially enhances the tumor-normal brain contrast of T1-weighted images for at least 92 hours. The data indicate a maximal enhancement of contrast between tumor and normal brain at 24 hours after injection, compared with 5 minutes for manganese (III) tetraphenylporphine sulfonate (TPPS4). The results also indicate that Mn-BOPP may have a slower uptake in the 9L glioma than Mn-TPPS4 but a longer retention in the tumor. Mn-BOPP is unique in that it represents, to the authors' knowledge, the first example of a single agent that can enhance contrast between tumor and normal tissue and be potentially effective as an agent for boron neutron capture therapy.

Animals↗
PubMedDate not supplied

Uptake of dextran-coated monocrystalline iron oxides in tumor cells and macrophages.

Although several dextran-coated iron oxide preparations are in preclinical and clinical use, little is known about the mechanism of uptake into cells. As these particles have been shown to accumulate in macrophages and tumor cells, we performed cellular uptake and inhibition studies with a prototypical monocrystalline iron oxide nanoparticle (MION). MION particles were labeled with fluorescein isothiocyanate or radioiodinated and purified by gel permeation chromatography. Two preparations of MION particles were used in cell experiments: nontreated MION and plasma-opsonized MION purified by gradient density purification. As determined by immunoblotting, opsonization resulted in C3, vitronectin, and fibronectin association with MION. Incubation of cells with fluorescent MION showed active uptake of particles in macrophages both before and after opsonization. In C6 tumor cells, however, intracellular MION was only detectable in dividing cells. Quantitatively, 125I-labeled MION was internalized into cells with uptake values ranging from 17 ng (in 9L gliosarcoma) to 970 ng iron per million cells for peritoneal macrophages. Opsonization increased MION uptake into macrophages sixfold, whereas it increased the uptake in C6 tumor cells only twofold. Results from uptake inhibition assay suggest that cellular uptake of nonopsonized (dextran-coated) MION particles is mediated by fluid-phase endocytosis, whereas receptor-mediated endocytosis is presumably responsible for the uptake of opsonized (protein-coated) particles.

Animals↗