Iron inhibits glioblastoma cell migration and polarization.

Glioblastoma is one of the deadliest malignancies facing modern oncology today. The ability of glioblastoma cells to diffusely spread into neighboring healthy brain makes complete surgical resection nearly impossible and contributes to the recurrent disease faced by most patients. Although research into the impact of iron on glioblastoma has addressed proliferation, there has been little investigation into how cellular iron impacts the ability of glioblastoma cells to migrate-a key question, especially in the context of the diffuse spread observed in these tumors. Herein, we show that increasing cellular iron content results in decreased migratory capacity of human glioblastoma cells. The decrease in migratory capacity was accompanied by a decrease in cellular polarization in the direction of movement. Expression of CDC42, a Rho GTPase that is essential for both cellular migration and establishment of polarity in the direction of cell movement, was reduced upon iron treatment. We then analyzed a single-cell RNA-seq dataset of human glioblastoma samples and found that cells at the tumor periphery had a gene signature that is consistent with having lower levels of cellular iron. Altogether, our results suggest that cellular iron content is impacting glioblastoma cell migratory capacity and that cells with higher iron levels exhibit reduced motility.

Common Mutation in the HFE Gene Modifies Recovery After Intracerebral Hemorrhage.

BACKGROUND: Intracerebral hemorrhage (ICH) is characterized by bleeding into the brain parenchyma. During an ICH, iron released from the breakdown of hemoglobin creates a cytotoxic environment in the brain through increased oxidative stress. Interestingly, the loss of iron homeostasis is associated with the pathological process of other neurological diseases. However, we have previously shown that the H63D mutation in the homeostatic iron regulatory (HFE) gene, prevalent in 28% of the White population in the United States, acts as a disease modifier by limiting oxidative stress. The following study aims to examine the effects of the murine homolog, H67D HFE, on ICH. METHODS: An autologous blood infusion model was utilized to create an ICH in the right striatum of H67D and wild-type mice. The motor recovery of each animal was assessed by rotarod. Neurodegeneration was measured using fluorojade-B and mitochondrial damage was assessed by immunofluorescent numbers of CytC+ (cytochrome C) neurons and CytC+ astrocytes. Finally, the molecular antioxidant response to ICH was quantified by measuring Nrf2 (nuclear factor-erythroid 2 related factor), GPX4 (glutathione peroxidase 4), and FTH1 (H-ferritin) levels in the ICH-affected and nonaffected hemispheres via immunoblotting. RESULTS: At 3 days post-ICH, H67D mice demonstrated enhanced performance on rotarod compared with wild-type animals despite no differences in lesion size. Additionally, H67D mice displayed higher levels of Nrf2, GPX4, and FTH1 in the ICH-affected hemisphere; however, these levels were not different in the contralateral, non-ICH-affected hemisphere. Furthermore, H67D mice showed decreased degenerated neurons, CytC+ Neurons, and CytC+ astrocytes in the perihematomal area. CONCLUSIONS: Our data suggest that the H67D mutation induces a robust antioxidant response 3 days following ICH through Nrf2, GPX4, and FTH1 activation. This activation could explain the decrease in degenerated neurons, CytC+ neurons, and CytC+ astrocytes in the perihematomal region, leading to the improved motor recovery. Based on this study, further investigation into the mechanisms of this neuroprotective response and the effects of the H63D HFE mutation in a population of patients with ICH is warranted.

Sexually dimorphic effect of H-ferritin genetic manipulation on survival and tumor microenvironment in a mouse model of glioblastoma.

PURPOSE: Iron plays a crucial role in various biological mechanisms and has been found to promote tumor growth. Recent research has shown that the H-ferritin (FTH1) protein, traditionally recognized as an essential iron storage protein, can transport iron to GBM cancer stem cells, reducing their invasion activity. Moreover, the binding of extracellular FTH1 to human GBM tissues, and brain iron delivery in general, has been found to have a sex bias. These observations raise questions, addressed in this study, about whether H-ferritin levels extrinsic to the tumor can affect tumor cell pathways and if this impact is sex-specific. METHODS: To interrogate the role of systemic H-ferritin in GBM we introduce a mouse model in which H-ferritin levels are genetically manipulated. Mice that were genetically manipulated to be heterozygous for H-ferritin (Fth1+/-) gene expression were orthotopically implanted with a mouse GBM cell line (GL261). Littermate Fth1 +/+ mice were used as controls. The animals were evaluated for survival and the tumors were subjected to RNA sequencing protocols. We analyzed the resulting data utilizing the murine Microenvironment Cell Population (mMCP) method for in silico immune deconvolution. mMCP analysis estimates the abundance of tissue infiltrating immune and stromal populations based on cell-specific gene expression signatures. RESULTS: There was a clear sex bias in survival. Female Fth1+/- mice had significantly poorer survival than control females (Fth1+/+). The Fth1 genetic status did not affect survival in males. The mMCP analysis revealed a significant reduction in T cells and CD8 + T cell infiltration in the tumors of females with Fth1+/- background as compared to the Fth1+/+. Mast and fibroblast cell infiltration was increased in females and males with Fth1+/- background, respectively, compared to Fth1+/+ mice. CONCLUSION: Genetic manipulation of Fth1 which leads to reduced systemic levels of FTH1 protein had a sexually dimorphic impact on survival. Fth1 heterozygosity significantly worsened survival in females but did not affect survival in male GBMs. Furthermore, the genetic manipulation of Fth1 significantly affected tumor infiltration of T-cells, CD8 + T cells, fibroblasts, and mast cells in a sexually dimorphic manner. These results demonstrate a role for FTH1 and presumably iron status in establishing the tumor cellular landscape that ultimately impacts survival and further reveals a sex bias that may inform the population studies showing a sex effect on the prevalence of brain tumors.

HFE genotype affects exosome phenotype in cancer.

Neuroblastoma is the third most common childhood cancer, and timely diagnosis and sensitive therapeutic monitoring remain major challenges. Tumor progression and recurrence is common with little understanding of mechanisms. A major recent focus in cancer biology is the impact of exosomes on metastatic behavior and the tumor microenvironment. Exosomes have been demonstrated to contribute to the oncogenic effect on the surrounding tumor environment and also mediate resistance to therapy. The effect of genotype on exosomal phenotype has not yet been explored. We interrogated exosomes from human neuroblastoma cells that express wild-type or mutant forms of the HFE gene. HFE, one of the most common autosomal recessive polymorphisms in the Caucasian population, originally associated with hemochromatosis, has also been associated with increased tumor burden, therapeutic resistance boost, and negative impact on patient survival. Herein, we demonstrate that changes in genotype cause major differences in the molecular and functional properties of exosomes; specifically, HFE mutant derived exosomes have increased expression of proteins relating to invasion, angiogenesis, and cancer therapeutic resistance. HFE mutant derived exosomes were also shown to transfer this cargo to recipient cells and cause an increased oncogenic functionality in those recipient cells.

HFE polymorphisms affect survival of brain tumor patients.

The HFE (high iron) protein plays a key role in the regulation of body iron. HFE polymorphisms (H63D and C282Y) are the common genetic variants in Caucasians. Based on frequency data, both HFE polymorphisms have been associated with increased risk in a number of cancers. The prevalence of the two major HFE polymorphisms in a human brain tumor patient populations and the impact of HFE polymorphisms on survival have not been studied. In the present study, there is no overall difference in survival by HFE genotype. However, male GBM patients with H63D HFE (H63D) have poorer overall survival than wild type HFE (WT) male GBM (p = 0.03). In GBM patients with the C282Y HFE polymorphism (C282Y), female patients have poorer survival than male patients (p = 0.05). In addition, female metastatic brain tumor patients with C282Y have shorter survival times post diagnosis than WT patients (p = 0.02) or male metastatic brain tumor patients with C282Y (p = 0.02). There is a tendency toward a lower proportion of H63D genotype in GBM patients than a non-tumor control group (p = 0.09) or other subtypes of brain tumors. In conclusion, our study suggests that HFE genotype impacts survival of brain tumor patients in a gender specific manner. We previously reported that glioma and neuroblastoma cell lines with HFE polymorphisms show greater resistance to chemo and radiotherapy. Taken together, these data suggest HFE genotype is an important consideration for evaluating and planning therapeutic strategies in brain tumor patients.

Analysis of anemia and iron supplementation among glioblastoma patients reveals sex-biased association between anemia and survival.

The association between anemia and outcomes in glioblastoma patients is unclear. We analyzed data from 1346 histologically confirmed adult glioblastoma patients in the TriNetX Research Network. Median hemoglobin and hematocrit levels were quantified for 6 months following diagnosis and used to classify patients as anemic or non-anemic. Associations of anemia and iron supplementation of anemic patients with median overall survival (median-OS) were then studied. Among 1346 glioblastoma patients, 35.9% of male and 40.5% of female patients were classified as anemic using hemoglobin-based WHO guidelines. Among males, anemia was associated with reduced median-OS compared to matched non-anemic males using hemoglobin (HR 1.24; 95% CI 1.00-1.53) or hematocrit-based cutoffs (HR 1.28; 95% CI 1.03-1.59). Among females, anemia was not associated with median-OS using hemoglobin (HR 1.00; 95% CI 0.78-1.27) or hematocrit-based cutoffs (HR: 1.10; 95% CI 0.85-1.41). Iron supplementation of anemic females trended toward increased median-OS (HR 0.61; 95% CI 0.32-1.19) although failing to reach statistical significance whereas no significant association was found in anemic males (HR 0.85; 95% CI 0.41-1.75). Functional transferrin-binding assays confirmed sexually dimorphic binding in resected patient samples indicating underlying differences in iron biology. Anemia among glioblastoma patients exhibits a sex-specific association with survival.

Uptake of H-ferritin by Glioblastoma stem cells and its impact on their invasion capacity.

PURPOSE: Iron acquisition is key to maintaining cell survival and function. Cancer cells in general are considered to have an insatiable iron need. Iron delivery via the transferrin/transferrin receptor pathway has been the canonical iron uptake mechanism. Recently, however, our laboratory and others have explored the ability of ferritin, particularly the H-subunit, to deliver iron to a variety of cell types. Here, we investigate whether Glioblastoma (GBM) initiating cells (GICs), a small population of stem-like cells, are known for their iron addiction and invasive nature acquire exogenous ferritin, as a source of iron. We further assess the functional impact of ferritin uptake on the invasion capacity of the GICs. METHODS: To establish that H-ferritin can bind to human GBM, tissue-binding assays were performed on samples collected at the time of surgery. To interrogate the functional consequences of H-ferritin uptake, we utilized two patient-derived GIC lines. We further describe H-ferritin's impact on GIC invasion capacity using a 3D invasion assay. RESULTS: H-ferritin bound to human GBM tissue at the amount of binding was influenced by sex. GIC lines showed uptake of H-ferritin protein via transferrin receptor. FTH1 uptake correlated with a significant decrease in the invasion capacity of the cells. H-ferritin uptake was associated with a significant decrease in the invasion-related protein Rap1A. CONCLUSION: These findings indicate that extracellular H-ferritin participates in iron acquisition to GBMs and patient-derived GICs. The functional significance of the increased iron delivery by H-ferritin is a decreased invasion capacity of GICs potentially via reduction of Rap1A protein levels.

Photodynamic Therapy for Glioblastoma: Illuminating the Path toward Clinical Applicability.

Glioblastoma (GBM) is the most common adult brain cancer. Despite extensive treatment protocols comprised of maximal surgical resection and adjuvant chemo-radiation, all glioblastomas recur and are eventually fatal. Emerging as a novel investigation for GBM treatment, photodynamic therapy (PDT) is a light-based modality that offers spatially and temporally specific delivery of anti-cancer therapy with limited systemic toxicity, making it an attractive option to target GBM cells remaining beyond the margins of surgical resection. Prior PDT approaches in GBM have been predominantly based on 5-aminolevulinic acid (5-ALA), a systemically administered drug that is metabolized only in cancer cells, prompting the release of reactive oxygen species (ROS), inducing tumor cell death via apoptosis. Hence, this review sets out to provide an overview of current PDT strategies, specifically addressing both the potential and shortcomings of 5-ALA as the most implemented photosensitizer. Subsequently, the challenges that impede the clinical translation of PDT are thoroughly analyzed, considering relevant gaps in the current PDT literature, such as variable uptake of 5-ALA by tumor cells, insufficient tissue penetrance of visible light, and poor oxygen recovery in 5-ALA-based PDT. Finally, novel investigations with the potential to improve the clinical applicability of PDT are highlighted, including longitudinal PDT delivery, photoimmunotherapy, nanoparticle-linked photosensitizers, and near-infrared radiation. The review concludes with commentary on clinical trials currently furthering the field of PDT for GBM. Ultimately, through addressing barriers to clinical translation of PDT and proposing solutions, this review provides a path for optimizing PDT as a paradigm-shifting treatment for GBM.

HFE polymorphisms influence the response to chemotherapeutic agents via induction of p16INK4A.

HFE is a protein that impacts cellular iron uptake. HFE gene variants are identified as risk factors or modifiers for multiple diseases. Using HFE stably transfected human neuroblastoma cells, we found that cells carrying the C282Y HFE variant do not differentiate when exposed to retinoic acid. Therefore, we hypothesized HFE variants would impact response to therapeutic agents. Both the human neuroblastoma and glioma cells that express the C282Y HFE variant are resistant to Temodar, geldanamycin and γ-radiation. A gene array analysis revealed that p16INK4A (p16) expression was increased in association with C282Y expression. Decreasing p16 protein by siRNA resulted in increased vulnerability to all of the therapeutic agents suggesting that p16 is responsible for the resistance. Decreasing HFE expression by siRNA resulted in a 85% decrease in p16 expression in the neuroblastoma cells but not the astrocytoma cells. These data suggest a potential direct relationship between HFE and p16 that may be cell specific or mediated by different pathways in the different cell types. In conclusion, the C282Y HFE variant impacts the vulnerability of cancer cells to current treatment strategies apparently by increasing expression of p16. Although best known as a tumor suppressor, there are multiple reports that p16 is elevated in some forms of cancer. Given the frequency of the HFE gene variants, as high as 10% of the Caucasian population, these data provide compelling evidence that the C282Y HFE variant should be part of a pharmacogenetic strategy for evaluating treatment efficacy in cancer cells.

Biological Activity of a Thiobarbituric Acid Compound in Neuroblastomas.

BACKGROUND/AIM: We have previously reported the identification of the cytotoxic chemotype compound-I (CC-I) from a chemical library screening against glioblastoma. MATERIALS AND METHODS: The biological activity of CC-I on drug-resistant neuroblastomas [e.g., HFE gene variant C282Y stably transfected human neuroblastoma SH-SY5Y cells (C282Y HFE/SH-SY5Y), SK-N-AS] was characterized using cell culture models and in vivo mouse tumor models. RESULTS: CC-I had potent cytotoxicity on therapy-resistant neuroblastoma cells and limited cytotoxicity on human primary dermal fibroblast cells. In addition, CC-I showed a robust anti-tumor effect on therapy-resistant human neuroblastoma C282Y HFE/SH-SY5Y cells but not on SK-N-AS cells in a subcutaneous tumor model. CC-I induced phosphorylation of heat shock protein 27 (HSP27), protein kinase B (Akt), and c-Jun N-terminal kinase (JNK) in C282Y HFE/SH-SY5Y neuroblastoma cells. CONCLUSION: CC-I may be an effective therapeutic option for therapy-resistant neuroblastomas, especially if they express the C282Y HFE gene variant. Its anti-tumor effects are possibly through HSP27-Akt-JNK activation.

Association Between Iron and Cholesterol in Neuroblastomas.

BACKGROUND/AIM: Neuroblastoma is the most common childhood extracranial solid malignancy. Although cancer cells need iron and lipids for active cell division, possible links between iron and lipid metabolism in neuroblastomas have not been studied. MATERIALS AND METHODS: We evaluated the levels and association between iron and cholesterol on in vitro neuroblastoma cancer models. RESULTS: We found that the levels of iron and cholesterol are diverse among neuroblastoma cell lines. There is a bi-directional association between iron and cholesterol in drug-resistant neuroblastoma SK-N-AS cells. In drug-resistant neuroblastoma cells, low concentration of an iron chelator did not have an impact on iron levels, but on cellular cholesterol levels. Furthermore, a cholesterol decreasing agent, simvastatin, influenced both iron and cholesterol levels in drug-resistant neuroblastoma cells. CONCLUSION: Cholesterol decreasing agents may be more effective than iron chelators for drug-resistant neuroblastoma treatment.

Efficacy of interleukin-13 receptor-targeted liposomal doxorubicin in the intracranial brain tumor model.

Human glioblastoma tumors selectively express receptors for interleukin 13 (IL-13). In a previous study, we showed that liposomes, when conjugated with IL-13, will deliver chemotherapeutics to a subcutaneous glioma tumor model in mice much more effectively than conventional unconjugated liposomes. Based on this observation, we developed an intracranial brain tumor model in nude mice using human U87 glioma cells. Mice receiving weekly i.p. injections of 15 mg/kg of doxorubicin encapsulated in IL-13-conjugated liposomes had a 5-fold reduction in the intracranial tumor volume over 6 weeks and four of seven animals survived >200 days after tumor implantation. In contrast, the animals receiving unconjugated liposomes with the same doxorubicin concentration did not survive beyond 35 days and there was no evidence of tumor size reduction. The presence of liposomes with doxorubicin in the tumor was shown by taking advantage of the selective expression of IL-13 receptors on the tumor cells and the endogenous fluorescence of doxorubicin. There was no increase in the indices of toxicity in animals receiving the doxorubicin-containing liposomes. Finally, a model of the blood-brain barrier was used to show that the nanovesicles do not harm the endothelial cells yet maintain their toxicity to astrocytoma cells. This approach is necessary to show the efficacy of this targeting platform for tumors in which the blood-brain barrier is not compromised and as a potential use of the nanovesicle system as a surveillance mechanism to prevent recurrence. These data show that IL-13 targeted nanovesicles are a viable option for the treatment of brain tumors.

Characterization of a Novel Barbituric Acid and Two Thiobarbituric Acid Compounds for Lung Cancer Treatment.

BACKGROUND/AIM: Previously, we reported the identification of a cytotoxic chemotype compound CC-I (1a), a derivative of thiobarbituric acid. We also reported the anticancer activity of a series of novel thio- and seleno-barbituric acid analogs. MATERIALS AND METHODS: We herein evaluated the effect of 1a and its modified compounds on in vitro and in vivo lung cancer models. RESULTS: The compounds 1b and 2a showed more potent cytotoxicity than 1a to lung cancer cells. Moreover, 1b did not have any cytotoxicity on normal cells, such as fibroblasts. In the human lung cancer A549 mouse tumor xenograft model, 1b and 2a showed more pronounced antitumor effects than 1a In the A549 lung cancer cells, 1a induced cell death mainly via JNK and p38 MAPK activation. However, compound 1b and 2a induced lung cancer cell death mostly through JNK activation. CONCLUSION: The results suggest that 1b and 2a can be useful therapeutic agents for lung cancer.

Liposomal delivery of ferritin heavy chain 1 (FTH1) siRNA in patient xenograft derived glioblastoma initiating cells suggests different sensitivities to radiation and distinct survival mechanisms.

Elevated expression of the iron regulatory protein, ferritin heavy chain 1 (FTH1), is increasingly being associated with high tumor grade and poor survival outcomes in glioblastoma. Glioma initiating cells (GICs), a small population of stem-like cells implicated in therapeutic resistance and glioblastoma recurrence, have recently been shown to exhibit increased FTH1 expression. We previously demonstrated that FTH1 knockdown enhanced therapeutic sensitivity in an astrocytoma cell line. Therefore, in this study we developed a liposomal formulation to enable the in vitro delivery of FTH1 siRNA in patient xenograft derived GICs from glioblastomas with pro-neural and mesenchymal transcriptional signatures to interrogate the effect of FTH1 downregulation on their radiation sensitivity. Transfection with siRNA decreased FTH1 expression significantly in both GICs. However, there were inherent differences in transfectability between pro-neural and mesenchymal tumor derived GICs, leading us to modify siRNA: liposome ratios for comparable transfection. Moreover, loss of FTH1 expression resulted in increased extracellular lactate dehydrogenase activity, executioner caspase 3/7 induction, substantial mitochondrial damage, diminished mitochondrial mass and reduced cell viability. However, only GICs from pro-neural glioblastoma showed marked increase in radiosensitivity upon FTH1 downregulation demonstrated by decreased cell viability, impaired DNA repair and reduced colony formation subsequent to radiation. In addition, the stemness marker Nestin was downregulated upon FTH1 silencing only in GICs of pro-neural but not mesenchymal origin. Using liposomes as a siRNA delivery system, we established FTH1 as a critical factor for survival in both GIC subtypes as well as a regulator of radioresistance and stemness in pro-neural tumor derived GICs. Our study provides further evidence to support the role of FTH1 as a promising target in glioblastoma.

Tim-2 is the receptor for H-ferritin on oligodendrocytes.

Oligodendrocytes stain more strongly for iron than any other cell in the CNS, and they require iron for the production of myelin. For most cell types transferrin is the major iron delivery protein, yet neither transferrin receptor protein nor mRNA are detectable in mature oligodendrocytes. Thus an alternative iron delivery mechanism must exist. Given the significant long term consequences of developmental iron deficiency and the iron requirements for normal myelination, identification of the iron delivery mechanism for oligodendrocytes is important. Previously we have reported that oligodendrocytes bind H-ferritin and that H-ferritin binds to white matter tracts in vivo. Recently, T cell immunoglobulin and mucin domain-containing protein-2 (Tim-2) was shown to bind and internalize H-ferritin. In the present study we show that Tim-2 is expressed on oligodendrocytes both in vivo and in vitro. Further, the onset of saturable H-ferritin binding in CG4 oligodendrocyte cell line is accompanied by Tim-2 expression. Application of a blocking antibody to the extracellular domain of Tim-2 significantly reduces H-ferritin binding to the differentiated CG4 cells and primary oligodendrocytes. Tim-2 expression on CG4 cells is responsive to iron; decreasing with iron loading and increasing with iron chelation. Taken together, these data provide compelling evidence that Tim-2 is the H-ferritin receptor on oligodendrocytes suggesting it is the primary mechanism for iron acquisition by these cells.

MLN8237 treatment in an orthoxenograft murine model for malignant peripheral nerve sheath tumors.

OBJECTIVEMalignant peripheral nerve sheath tumors (MPNSTs) are soft-tissue sarcomas arising from peripheral nerves. MPNSTs have increased expression of the oncogene aurora kinase A, leading to enhanced cellular proliferation. This makes them extremely aggressive with high potential for metastasis and a devastating prognosis; 5-year survival estimates range from a dismal 15% to 60%. MPNSTs are currently treated with resection (sometimes requiring limb amputation) in combination with chemoradiation, both of which demonstrate limited effectiveness. The authors present the results of immunohistochemical, in vitro, and in vivo analyses of MLN8237 for the treatment of MPNSTs in an orthoxenograft murine model.METHODSImmunohistochemistry was performed on tumor sections to confirm the increased expression of aurora kinase A. Cytotoxicity analysis was then performed on an MPNST cell line (STS26T) to assess the efficacy of MLN8237 in vitro. A murine orthoxenograft MPNST model transfected to express luciferase was then developed to assess the efficacy of aurora kinase A inhibition in the treatment of MPNSTs in vivo. Mice with confirmed tumor on in vivo imaging were divided into 3 groups: 1) controls, 2) mice treated with MLN8237, and 3) mice treated with doxorubicin/ifosfamide. Treatment was carried out for 32 days, with imaging performed at weekly intervals until postinjection day 42. Average bioluminescence among groups was compared at weekly intervals using 1-way ANOVA. A survival analysis was performed using Kaplan-Meier curves.RESULTSImmunohistochemical analysis showed robust expression of aurora kinase A in tumor cells. Cytotoxicity analysis revealed STS26T susceptibility to MLN8237 in vitro. The group receiving treatment with MLN8237 showed a statistically significant difference in tumor size compared with the control group starting at postinjection day 21 and persisting until the end of the study. The MLN8237 group also showed decreased tumor size compared with the doxorubicin/ifosfamide group at the conclusion of the study (p = 0.036). Survival analysis revealed a significantly increased median survival in the MLN8237 group (83 days) compared with both the control (64 days) and doxorubicin/ifosfamide (67 days) groups. A hazard ratio comparing the 2 treatment groups showed a decreased hazard rate in the MLN8237 group compared with the doxorubicin/ifosfamide group (HR 2.945; p = 0.0134).CONCLUSIONSThe results of this study demonstrate that MLN8237 is superior to combination treatment with doxorubicin/ifosfamide in a preclinical orthoxenograft murine model. These data have major implications for the future of MPNST research by providing a robust murine model as well as providing evidence that MLN8237 may be an effective treatment for MPNSTs.

Tumor targeted delivery of doxorubicin in malignant peripheral nerve sheath tumors.

Peripheral nerve sheath tumors are benign tumors that have the potential to transform into malignant peripheral nerve sheath tumors (MPNSTs). Interleukin-13 receptor alpha 2 (IL13Rα2) is a cancer associated receptor expressed in glioblastoma and other invasive cancers. We analyzed IL13Rα2 expression in several MPNST cell lines including the STS26T cell line, as well as in several peripheral nerve sheath tumors to utilize the IL13Rα2 receptor as a target for therapy. In our studies, we demonstrated the selective expression of IL13Rα2 in several peripheral nerve sheath tumors by immunohistochemistry (IHC) and immunoblots. We established a sciatic nerve MPNST mouse model in NIH III nude mice using a luciferase transfected STS26T MPNST cell line. Similarly, analysis of the mouse sciatic nerves after tumor induction revealed significant expression of IL13Rα2 by IHC when compared to a normal sciatic nerve. IL13 conjugated liposomal doxorubicin was formulated and shown to bind and internalized in the MPNST cell culture model demonstrating cytotoxic effect. Our subsequent in vivo investigation in the STS26T MPNST sciatic nerve tumor model indicated that IL13 conjugated liposomal doxorubicin (IL13LIPDXR) was more effective in inhibiting tumor progression compared to unconjugated liposomal doxorubicin (LIPDXR). This further supports that IL13 receptor targeted nanoliposomes is a potential approach for treating MPNSTs.

Exosomes impact survival to radiation exposure in cell line models of nervous system cancer.

Radiation is utilized in the therapy of more than 50% of cancer patients. Unfortunately, many malignancies become resistant to radiation over time. We investigated the hypothesis that one method of a cancer cell's ability to survive radiation occurs through cellular communication via exosomes. Exosomes are cell-derived vesicles containing DNA, RNA, and protein. Three properties were analyzed: 1) exosome function, 2) exosome profile and 3) exosome uptake/blockade. To analyze exosome function, we show radiation-derived exosomes increased proliferation and enabled recipient cancer cells to survive radiation in vitro. Furthermore, radiation-derived exosomes increased tumor burden and decreased survival in an in vivo model. To address the mechanism underlying the alterations by exosomes in recipient cells, we obtained a profile of radiation-derived exosomes that showed expression changes favoring a resistant/proliferative profile. Radiation-derived exosomes contain elevated oncogenic miR-889, oncogenic mRNAs, and proteins of the proteasome pathway, Notch, Jak-STAT, and cell cycle pathways. Radiation-derived exosomes contain decreased levels of tumor-suppressive miR-516, miR-365, and multiple tumor-suppressive mRNAs. Ingenuity pathway analysis revealed the most represented networks included cell cycle, growth/survival. Upregulation of DNM2 correlated with increased exosome uptake. To analyze the property of exosome blockade, heparin and simvastatin were used to inhibit uptake of exosomes in recipient cells resulting in inhibited induction of proliferation and cellular survival. Because these agents have shown some success as cancer therapies, our data suggest their mechanism of action could be limiting exosome communication between cells. The results of our study identify a novel exosome-based mechanism that may underlie a cancer cell's ability to survive radiation.

Targeting IL-13Rα2 for effective treatment of malignant peripheral nerve sheath tumors in mouse models.

OBJECTIVEMalignant peripheral nerve sheath tumors (MPNSTs) are aggressive soft tissue sarcomas that harbor a high potential for metastasis and have a devastating prognosis. Combination chemoradiation aids in tumor control and decreases tumor recurrence but causes deleterious side effects and does not extend long-term survival. An effective treatment with limited toxicity and enhanced efficacy is critical for patients suffering from MPNSTs.METHODSThe authors recently identified that interleukin-13 receptor alpha 2 (IL-13Rα2) is overexpressed on MPNSTs and could serve as a precision-based target for delivery of chemotherapeutic agents. In the work reported here, a recombinant fusion molecule consisting of a mutant human IL-13 targeting moiety and a point mutant variant of Pseudomonas exotoxin A (IL-13.E13 K-PE4E) was utilized to treat MPNST in vitro in cell culture and in an in vivo murine model.RESULTSIL-13.E13 K-PE4E had a potent cytotoxic effect on MPNST cells in vitro. Furthermore, intratumoral administration of IL-13.E13 K-PE4E to orthotopically implanted MPNSTs decreased tumor burden 6-fold and 11-fold in late-stage and early-stage MPNST models, respectively. IL-13.E13 K-PE4E treatment also increased survival by 23 days in the early-stage MPNST model.CONCLUSIONSThe current MPNST treatment paradigm consists of 3 prongs: surgery, chemotherapy, and radiation, none of which, either singly or in combination, are curative or extend survival to a clinically meaningful degree. The results presented here provide the possibility of intratumoral therapy with a potent and highly tumor-specific cytotoxin as a fourth treatment prong with the potential to yield improved outcomes in patients with MPNSTs.

Interleukin-13 receptor-targeted nanovesicles are a potential therapy for glioblastoma multiforme.

The difficulties associated with treatment of malignant brain tumors are well documented. For example, local infiltration of high-grade astrocytomas prevents the complete resection of all malignant cells. It is, therefore, critical to develop delivery systems for chemotherapeutic agents that ablate individual cancer cells without causing diffuse damage to surrounding brain tissue. Here, we describe sterically stable human interleukin-13 (IL-13)-conjugated liposomes, which efficiently bind to the brain cancer cells that overexpress the IL-13 receptor alpha2 protein. The conjugated liposomes bind to glioblastoma multiforme tissue specimens but not to normal cortex. Conjugating the liposomes with human IL-13 allows for specific binding to glioma cells and uptake of the liposomes via endocytosis. Delivering doxorubicin to glioma cells by IL-13-conjugated liposomes results in enhanced cytotoxicity and increased accumulation and retention of drug in the glioma cells compared with delivery of free drug. The therapeutic potential and targeting efficacy of the IL-13-conjugated liposomes carrying doxorubicin was tested in vivo using a s.c. glioma tumor mouse model. Animals receiving i.p. injections of IL-13-conjugated liposomes carrying doxorubicin for 7 weeks had a mean tumor volume of 37 mm3 compared with a mean volume of 192 mm3 in animals injected with nontargeted liposomes. These results strongly suggest that IL-13-conjugated liposomes carrying cytotoxic agents are a feasible approach for creating a nanovesicle drug delivery system for brain tumor therapy.