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.

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.

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.

TMIC-34. INVESTIGATING THE EFFECT OF IRON IN GLIOBLASTOMA CELL POLARIZATION AND MIGRATION

Glioblastoma represents one of the most difficult-to-treat malignancies as evidenced by the poor prognosis associated with a diagnosis. The ability of glioblastoma cells to diffusely infiltrate into healthy brain tissue renders complete surgical resection challenging. Consequently, a large majority of glioblastoma patients end up with recurrent disease despite receiving maximally feasible surgical resection and rigorous chemoradiation. This work examined how modulation of cellular iron levels in T98G and LN229 glioblastoma cells impacted migratory capacity. Treatment of T98G or LN229 glioblastoma cells with iron in the form of ferric ammonium citrate (FAC) resulted in significantly reduced migration as assessed by time-lapse phase contrast imaging and wound healing assays. The iron-induced reduction in migration was able to be rescued by the addition of equimolar concentrations of deferoxamine, an iron chelator. Cellular proliferation in response to the iron treatments was quantified using both optical confluence and nucleic-acid-based proliferation assays and it was found that iron treatment at the concentrations used for the migration assays (0 – 300 µM FAC) did not result in reduced proliferation. Mechanistically probing iron’s impact on cell migration revealed that addition of iron resulted in decreased expression of Cdc42, a Rho GTPase that is essential to determining cellular polarity during migration. Functional cellular polarization assays further confirmed that reduced expression of Cdc42 corresponded to reduced cellular polarization. Bioinformatic analysis of CDC42 transcripts revealed the presence of potential iron-responsive-elements that may drive the iron-induced reduction in Cdc42 expression. This work highlights the importance of iron biology in impacting glioblastoma cell phenotype and potentially glioblastoma patient outcomes.

Abstract 2430: The role of cellular iron and the homeostatic iron regulator (HFE) in high-grade brain tumor cell migration

High-grade brain tumors such as grade III astrocytoma and glioblastoma represent among the most difficult to manage malignancies facing oncological practice. Diffuse migration and invasion into adjacent healthy brain tissue yields complete surgical resection of these tumors unfeasible. As a result, despite receiving maximal surgical resection and an aggressive course of chemoradiation, the majority of high-grade brain tumor patients suffer from recurrent disease. Increased expression levels of the homeostatic iron regulator gene (HFE) in high-grade brain tumors have been correlated with poorer outcomes. HFE is known to influence cellular iron metabolism by inhibiting transferrin-mediated iron uptake yet little is known regarding how HFE or iron impact the migratory capabilities of high-grade brain tumor cells. In order to better understand how HFE expression and cellular iron metabolism influence cell migration in high grade brain tumors, we utilized brain tumor cell lines that had been genetically manipulated to express different levels of HFE. We observed that knocking down HFE in KR158 or LN229 glioma cell lines resulted in significantly decreased migratory capacity. Since HFE is known to inhibit transferrin mediated iron uptake, we studied how directly modulating the iron status of glioma cells impacted their ability to migrate. Treatment of a panel of glioma cell lines: LN229, T98G, U87, KR158, with iron in the form of hemin or ferric ammonium citrate resulted in significantly reduced migration. Furthermore, the iron-induced reduction in migration could be rescued by the addition of deferoxamine, an iron chelator. Cell viability in response to the iron treatments was assayed and found to not be significantly altered - suggesting that cellular iron status was influencing migratory capacity independent of cell viability. To gain mechanistic insights into HFE and iron-induced effects on cell migration, we analyzed the Chinese Glioma Genome Atlas (CGGA) for correlations between HFE and the Rho GTPases RHOA, RAC1, and CDC42 – genes which are known to play a crucial role in determining the migratory capacity of cancer cells. Interestingly, we found statistically significant correlations between the Rho GTPases RHOA, RAC1, CDC42 and HFE in both grade III astrocytoma and glioblastoma patient cohorts. Immunoblotting of iron treated glioma cell lines demonstrated that expression of RhoA and Cdc42 was reduced suggesting that alterations in Rho GTPase expression and signaling may play a role in iron-induced effects on cell migration. Our results demonstrate that targeting cancer cell iron metabolism as an addition to existing treatment regimens may be a promising avenue for further investigation.

Citation Format: Ganesh Shenoy, Katie Troike, Kondaiah Palsa, Madison Kuhn, Quinn Wade, Becky Slagle-Webb, Amanda Snyder, Chachrit Khunsriraksakul, Justin D. Lathia, Dhimant Desai, Hong-Gang Wang, Elizabeth Proctor, James R. Connor. The role of cellular iron and the homeostatic iron regulator (HFE) in high-grade brain tumor cell migration [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2430.

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.

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.

CSIG-16. SEXUAL DIMPORHISM IN IRON ACQUISITION IN GLIOBLASTOMA

Glioblastoma (GBM) is the most aggressive brain cancer. Sex differences in incidence and clinical outcomes have been reported, however, our knowledge of contributing mechanisms is limited. Iron acquisition is key to robust tumor growth. Upregulation of Transferrin (Tf, iron transport protein)/Transferrin receptor (TfR) is found in multiple different cancers. We have identified H-ferritin (FTH1) as involved in iron transport and explore its uptake in GBM in this study. We interrogated iron uptake in a syngeneic orthotopic mouse model (GL261 cells) using male and female mice. After the tumors were established, radioactive 125I labeled Tf and FTH1 proteins were injected retro-orbitally in the mice. After 24 hours, tumors were removed, homogenized and analyzed for Tf and FTH1 uptake. There was a significant difference in Tf uptake into the tumor versus matched non-tumor tissue in both males and females and the uptake in the tumors was 1.5-fold higher in males than females. There was no significant difference in FTH1 uptake between male and female tumors nor between tumor and matched non-tumor brain tissue. Binding analyses were performed on homogenized samples of human male and female GBM tissue samples using 125I labeled Tf and FTH1. Tumors from males had increased binding of both proteins compared to tumors from females. We next queried the TCGA database and found in females, high TfR expression was associated with poor survival but not in males. TCGA database revealed a robust expression of Tim1, a putative receptor for FTH1, but its expression did not relate to survival. In summary, this study demonstrates FTH1 binding to GBMs and sexual dimorphism in iron acquisition via Tf and survival.

TAMI-43. IMPACT OF SEX AND RADIATION ON IRON TRAFFICKING IN BONE MARROW DERIVED MACROPHAGES

The tumor microenvironment in glioblastoma provides cancer cells with favorable conditions to proliferate and invade surrounding tissues. Macrophages comprise a large portion of the glioblastoma tumor microenvironment (TME) both in terms of volume and function. These cells have been reported to influence tumor progression by modulating immune responses, remodeling extracellular matrix, and providing nutrients to cancer cells among numerous other functions. Radiation therapy forms one of the pillars of glioblastoma management along with surgical resection and chemotherapy. Here we investigated the effects of radiation on macrophage iron metabolism. Using mouse bone-marrow-derived macrophages (BMDMs) we performed in-vitro 59Fe radiotracer assays to study how radiation exposure modified iron trafficking in these cells. We found that low dose radiation at 0.25, 0.5, or 2 Gy from a 60Co source stimulated iron release from the BMDMs with maximal release occurring at 0.5 Gy. Moreover, we observed that iron release was dependent on the amount of serum present in culture media with cells cultured in 20% fetal bovine serum (FBS) showing reduced iron release profiles compared to those cultured in 10% or 1% FBS. Since glioblastoma patients exhibit sexually dimorphic survival outcomes, we investigated whether these radiation-induced responses occurred in a sexually dimorphic pattern. At radiation doses of 0.25 Gy we observed that male macrophages tended to release more iron than female macrophages despite no differences in iron uptake between the sexes – raising the question as to whether differential iron trafficking in response to treatment contributes to the poorer survival outcomes observed in males. Our data suggest that delineating how supporting cells such as macrophages respond to glioblastoma treatment regimens may provide insights into addressing mechanisms of treatment resistance and further our understanding of the sexual dimorphism observed in patient outcomes.

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.

TMIC-31. IMPACT OF IRON ON MACROPHAGE IMMUNE PHENOTYPE IN THE GLIOBLASTOMA TUMOR MICROENVIRONMENT

The tumor microenvironment (TME) in glioblastoma presents a significant hurdle to effective immunotherapies as it consists of an immunosuppressive niche that results in inhibition of anti-tumor immunity. Macrophages comprise a large portion of the glioblastoma TME as they are prolific secretors of immunosuppressive cytokines and can comprise of up to 30% of tumor volume. In addition to their crucial role in immune function, macrophages are important players in iron regulation owing to their ability to efficiently sequester and release iron. We studied the impact of iron status in macrophage anti-tumor immune functions and phenotypic plasticity using RAW264.7 macrophages and bone-marrow-derived macrophages (BMDMs). Using RAW264.7 cells, we found that the iron status of macrophages impacts their immune function by modulating expression of the co-stimulation membrane proteins CD80 and CD86 as well as the mannose receptor CD206. Interestingly, the iron-mediated immunomodulation was dependent on the formulation of iron with nanoparticle formulations such as ferumoxytol (Fe-NP) upregulating CD80, CD86, and decreasing CD206 while ferric ammonium citrate (FAC) downregulated CD80, CD86 and upregulated CD206. We analyzed expression of inflammatory cytokines in BMDMs with multiplex cytokine analysis and found that both FAC and Fe-NP increased expression of the chemotactic signals CXCL10, CCL1, CCL3, and CCL4. Additionally, we found that iron status impacts the ability of macrophages to repolarize from an inflammatory, immune-activating phenotype into an immunosuppressive phenotype upon exposure to glioblastoma tumor-conditioned media. We used qRT-PCR to examine gene expression of the tumor immunity-related genes TNFa, IL1B, NOS2, and IL10 and found that iron loaded RAW264.7 macrophages stimulated with lipopolysaccharide resisted repolarization into an immunosuppressive phenotype 24 hours after exposure to glioblastoma tumor-conditioned media. Our results suggest that understanding the link between iron status and immune function in the tumor microenvironment may be an important step in improving therapies against glioblastoma.

EXTH-63. LIPOSOMAL DELIVERY OF FERRITIN HEAVY CHAIN (FTH1) siRNA RESULTS IN INCREASED RADIATION SENSITIVITY IN PATIENT DERIVED GLIOMA INITIATING CELLS

Glioblastoma (GBM) is the most lethal and incurable brain cancer. Despite maximum treatment, high recurrence rates result in median survival of less than 2 years. A subset of treatment resistant cells within GBM known as glioma initiating cells (GICs) are implicated in recurrence and exhibit ferritin overexpression. High expression of ferritin is known to be associated with poor overall survival in GBM patients. Our previous finding showed that downregulation of the ferritin heavy chain subunit (FTH1) enhanced treatment sensitivity in astrocytoma cells. Recently, functional importance of FTH1 in GICs was demonstrated by shRNA silencing leading to ablation of tumorigenic ability. We therefore posited that disrupting iron metabolism through FTH1 knockdown would radiosensitize GICs. Thus we developed multivalent cationic liposomes that enabled delivery of FTH1 siRNA to patient derived GICs isolated from pro-neural (PN) and mesenchymal (Mes) GBM. In both subtypes, FTH1 loss led to increased apoptosis and reduced cell viability. When exposed to radiation, PN GICs were unable to repair and recover from DNA damage, leading to a further decrease in cell viability and a complete loss of reproductive clonogenic potential unlike their more radioresistant Mes counterparts. Moreover, expression of stem cell marker Nestin was markedly reduced in PN but not Mes GICs. Thus, FTH1 loss is detrimental to both GIC subtypes, it seems to be critical for maintaining stemness and radiation resistance of PN GICs. These findings further support the viability of FTH1 as a therapeutic target in GBM.

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.

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.

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.

Abstract 4065: Association study between iron and cholesterol for the treatment of drug resistant neuroblastoma

Neuroblastoma is the most common childhood extracranial solid malignancy. Although cancer cells need more iron and lipids for their active cell metabolism, possible links between iron, mutations in genes involved in iron metabolism (e.g., HFE) and lipid metabolism have not been studied well. We determined the HFE genotype in human neuroblastoma cells as well as patients. Neuroblastoma cells and patients have C282Y HFE mutation rates (~12%) that are similar to those of the general Caucasian population. While cultured cells derived from drug resistant neuroblastomas had less cholesterol, they expressed more ferritin, and contained more iron, than cells derived from drug susceptible tumors. In drug resistant neuroblastoma CHLA-171 cells, siRNA induced alteration of HFE expression had no effect on their iron levels but decreased their cholesterol. Results of in vitro experiments indicated that simvastatin, an inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG-CoAR), was cytotoxic to drug resistant cells as was the iron chelator di-2-pyridylketone-4-cyclohexyl-4-methyl-3-thiosemicarbazone (DpC). In vivo, the anti-tumor effect of simvastatin administered orally was minimal. In summary, we found i) an inverse association between ferritin and HMG-CoAR expression in neuroblastoma cells that was reflected in their iron and cholesterol levels, and ii) that the most cytotoxic cholesterol inhibitor of neuroblastoma cells was simvastatin, while the most cytotoxic iron chelation agent was DpC. Our results indicate that it may be possible to use HFE genotype to develop a precision medicine approach to use certain iron chelators and/or cholesterol decreasing agents in the treatment of drug resistant neuroblastomas. Our results also indicate that alterations in iron and cholesterol metabolism are part of the cell’s drug resistance mechanism in neuroblastomas.

Citation Format: Sang Y. Lee, Becky Slagle-Webb, Cara-Lynne Schengrund, James Connor. Association study between iron and cholesterol for the treatment of drug resistant neuroblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4065. doi:10.1158/1538-7445.AM2017-4065

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.

MRI contrast agent for targeting glioma: interleukin-13 labeled liposome encapsulating gadolinium-DTPA

BACKGROUND

Detection of glioma with MRI contrast agent is limited to cases in which the blood-brain barrier (BBB) is compromised as contrast agents cannot cross the BBB. Thus, an early-stage infiltrating tumor is not detectable. Interleukin-13 receptor alpha 2 (IL-13Rα2), which has been shown to be overexpressed in glioma, can be used as a target moiety. We hypothesized that liposomes conjugated with IL-13 and encapsulating MRI contrast agent are capable of passing through an intact BBB and producing MRI contrast with greater sensitivity.

METHODS

The targeted MRI contrast agent was created by encapsulating Magnevist (Gd-DTPA) into liposomes conjugated with IL-13 and characterized by particle size distribution, cytotoxicity, and MRI relaxivity. MR image intensity was evaluated in the brain in normal mice post injection of Gd-DTPA and IL-13-liposome-Gd-DTPA one day apart. The specificity for glioma detection by IL-13-liposome-Gd-DTPA was demonstrated in an intracranial glioma mouse model and validated histologically.

RESULTS

The average size of IL-13-liposome-Gd-DTPA was 137 ± 43 nm with relaxivity of 4.0 ± 0.4 L/mmole-s at 7 Tesla. No significant cytotoxicity was observed with MTS assay and serum chemistry in mice. The MRI signal intensity was enhanced up to 15% post injection of IL-13-liposome-Gd-DTPA in normal brain tissue following a similar time course as that for the pituitary gland outside of the BBB. MRI enhanced by IL-13-liposome-Gd-DTPA detected small tumor masses in addition to those seen with Magnevist-enhanced MRI.

CONCLUSIONS

IL-13-liposome-Gd-DTPA is able to pass through the uncompromised BBB and detect an early stage glioma that cannot be seen with conventional contrast-enhanced MRI.

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.

Abstract B06: Development of novel thiobarbituric acid derivative compounds for treatment of lung cancers

Previously, we reported the identification of a cytotoxic chemotype compound CC-I (a derivative of thiobarbituric acid) that is effective against chemotherapy resistant glioblastomas (GBMs) and neuroblastoma in an in vitro cell culture and in vivo mouse tumor models. In this study, we determined the cytotoxicity of CC-I and structurally similar compounds along in lung cancers to determine whether CC-I is toxic to lung cancers and to identify additional analog compounds that could be more toxic than CC-I. We designed several CC-I analog compounds by manipulating functional substitutions at N1-, N3- and C5-positions (either furan ring or benzene ring) of CC-I. For example, the novel compounds were synthesized starting from substituted thioureas, key precursors for the synthesis of substituted thiobarbituric acids, and finally by condensing cinnamaldehyde (CMC-2 series: benzene ring compound) or trans-3-(2-furyl)-acrolein (CC-I series: furan ring compound) with appropriately substituted thiobarbituric acids in the presence of catalytic amounts of pyridine. We used MTS cell proliferation or SRB cytotoxicity assay to determine the toxic level of compounds on the human lung cancer cell lines (e.g., A549, H520, H460, H69). The data suggest that the functional group at N1-, N3- and C5 sites is important for toxicity. Among the compounds with similar structures, CC-I-v3 and CC-I-v4 are the two most cytotoxic compounds to lung cancer cells and also the cisplatin resistant lung cancer cell lines such as H1993 and H520. In some of the cell lines we investigated, CC-I-v1 and CMC-2 compounds showed greater toxicity than CC-I compound. Currently, we are studying the anti-tumor effect of these compounds in an in vivo nude mouse tumor model. In summary, this structure-activity study clearly indicates that we can develop more efficacious compounds compared to our original compounds by rational modifications of the chemotype compounds.

[This project is supported by the Elsa U. Pardee Foundation]

Citation Format: Sang Y. Lee, Srinivasa Ramisetti, Becky Slagle-Webb, Arun K. Sharma, James R. Connor. Development of novel thiobarbituric acid derivative compounds for treatment of lung cancers. [abstract]. In: Proceedings of the AACR-IASLC Joint Conference on Molecular Origins of Lung Cancer; 2014 Jan 6-9; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2014;20(2Suppl):Abstract nr B06.

Abstract 5410: Down regulating heavy chain ferritin gene increasesthe radiation therapeutic efficacy for treatment of glioma

Gliomas, especially glioblastoma multiforme are resistant to radiation and chemotherapy. Therefore, efforts to develop new course of therapy to enhance efficacy of treatment strategies are obviously critical. We hypothesized that disrupting iron homeostasis in malignant tumor cells could prove effective at negatively affecting tumor growth because cancer cells have a robust iron requirement consistent with their rapid growth and high metabolic rates. The high levels of iron uptake require a mechanism to limit iron induced oxidative damage. This function is the responsibility of ferritin; an iron storage protein with 24 subunits of two types of chains light and heave chains. Heavy chain ferritin (H-ferritin) has been found in the nucleus of tumor cells where it appears to protect DNA from oxidative damage and promote transcription. We hypothesized that silencing the H-ferritin gene could increase the sensitivity of tumors cells to radiation. On the other hand, our previous data already demonstrated that silencing the H-ferritin gene increased chemotherapeutic efficacy for treating gliomas. To test our present hypothesis, the H-ferritin gene will be silenced via a cationic liposome carrying siRNA. We have chosen glioma cell lines (U251, U87 and MNSF) as our in vitro model. Subcutaneous glioma tumor in mouse model (athymic nude mice) was chosen as our in vivo model. Our preliminary in vitro data demonstrated silencing the H-ferritin gene in U251 cells leads to a 50% increase in cell death at 20 Gy for 24, 48 and 72 hours post radiation. Intratumoral injections of cationic liposomes containing H-ferritin siRNA reduced the effective in vivo dose of radiation for tumor suppression by more than 90% at 7 weeks. A supercoil relaxation assay demonstrated that H-ferritin, but not L-ferritin directly protects DNA from radiation by maintaining DNA in a relaxed from. We will further test our hypothesis in glioma-U87, neurofibroma-sNF96.2 and breast cancer-MCF-7 cells. As of now our data shows that silencing the H-ferritin gene appears to be an effective way to increase the sensitivity of the glioma tumors to radiation, which sheds light on increasing the radiation therapeutic efficacy for treatment of malignant tumors.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 5410. doi:10.1158/1538-7445.AM2011-5410

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.

Heavy chain ferritin siRNA delivered by cationic liposomes increases sensitivity of cancer cells to chemotherapeutic agents

Approximately half of all gliomas are resistant to chemotherapy, and new therapeutic strategies are urgently needed to treat this cancer. We hypothesized that disrupting iron homeostasis in glioma cells could block tumor growth, based on an acute requirement for high levels of iron to meet energy requirements associated with their rapid growth. Ferritin is best known as an intracellular iron storage protein, but it also localizes to tumor cell nuclei where it seems to protect DNA from oxidative damage and to promote transcription. In this study, we hypothesize that silencing the H-ferritin (heavy chain ferritin) gene could increase tumor sensitivity to chemotoxins. To test this hypothesis, H-ferritin siRNA was delivered to several human cancer cell lines by using cationic liposomes (C-liposome). H-ferritin siRNA decreased protein expression by 80% within 48 hours, and this decrease was associated with more than 50% decrease in the LD(50) for DNA-alkylating agent carmustine (BCNU), which is commonly used to treat glioma in clinic. In a subcutaneous mouse model of human glioma, intratumoral injections of liposomes containing H-ferritin siRNA reduced the effective dose of BCNU needed for tumor suppression by more than 50%. A plasmid supercoil relaxation assay showed that H-ferritin specifically and directly protected DNA from BCNU treatment. H-ferritin siRNA additionally seemed to increase apoptosis in glioma cells in vitro upon H-ferritin knockdown. Overall, our results illustrate how silencing H-ferritin can effectively sensitize tumors to chemotherapy and also show the ability of C-liposomes to serve as a novel in vivo delivery tool for siRNAs.