GS-nitroxide (JP4-039)-mediated radioprotection of human Fanconi anemia cell lines

Chemical Carcinogen (3-Methylcholanthrene)-induced Pleomorphic Rhabdomyosarcomas in Fanconi Anemia Fancd2-/-, Fancg-/- (C57BL/6), Fancd2-/- (129/Sv) Mice

BACKGROUND/AIM

Radiation oncologists are reluctant to treat cancer in Fanconi Anemia (FA) patients due to their lack of homologous recombination repair of DNA strand breaks in normal tissues. To determine the therapeutic effects of irradiation and combination chemotherapy on cancer in syngeneic, radiosensitive FA mice, we derived transplantable cancers of the same genotype in three FA mouse strains.

MATERIALS AND METHODS

Fancd2-/- mice on a C57BL/6 or Sv/129 background and Fancg-/- mice (C57BL/6 background) that received 3-methylcholanthrene (3-MCA), were monitored for the development of subcutaneous tumors.

RESULTS

Tumors were induced at the site of 3-MCA injection, and tumor cell lines were established and found to be transplantable. Explanted tumors were identified as pleomorphic/rhabdomyosarcomas using immunohistochemical biomarkers.

CONCLUSION

These transplantable FA mouse tumor cell lines should be valuable for testing effects of new radiation therapy protocols including FLASH high dose rate radiation delivery, immunotherapies, and combined radiation and chemotherapy treatments for radiosensitive FA patients.

Chemical Carcinogen (Dimethyl-benzanthracene) Induced Transplantable Cancer in Fanconi Anemia (Fanca-/-) Mice

BACKGROUND/AIM

Patients with radiation sensitive Fanconi anemia (FA) are presenting with cancers of the oral cavity, oropharynx, and other anatomic locations.

MATERIALS AND METHODS

Animal models for cancer in FA mice used orthotopic tumors from wild type mice. We derived a cancer cell line from Fanca-/- mice by topical application of the chemical carcinogen dimethyl benzanthracene (DMBA).

RESULTS

A Fanca-/- mouse rhabdomyosarcoma was derived from a Fanca-/- (129/Sv) mouse. The in vitro clonogenic survival of the Fanca-/- clone 6 cancer cell line was consistent with the FA genotype. Transplanted tumors demonstrated hypoxic centers surrounded by senescent cells.

CONCLUSION

This Fanca-/- mouse syngeneic cancer should provide a valuable resource for discovery and development of new normal tissue radioprotectors for patients with FA and cancer.

Soluble factors secreted by human Wharton’s jelly mesenchymal stromal/stem cells exhibit therapeutic radioprotection: A mechanistic study with integrating network biology

BACKGROUND

Human Wharton’s jelly-derived mesenchymal stromal/stem cells (hWJ-MSCs) have gained considerable attention in their applications in cell-based therapy due to several advantages offered by them. Recently, we reported that hWJ-MSCs and their conditioned medium have significant therapeutic radioprotective potential. This finding raised an obvious question to identify unique features of hWJ-MSCs over other sources of stem cells for a better understanding of its radioprotective mechanism.

AIM

To understand the radioprotective mechanism of soluble factors secreted by hWJ-MSCs and identification of their unique genes.

METHODS

Propidium iodide staining, endogenous spleen colony-forming assay, and survival study were carried out for radioprotection studies. Homeostasis-driven proliferation assay was performed for in vivo lymphocyte proliferation. Analysis of RNAseq data was performed to find the unique genes of WJ-MSCs by comparing them with bone marrow mesenchymal stem cells, embryonic stem cells, and human fibroblasts. Gene enrichment analysis and protein-protein interaction network were used for pathway analysis.

RESULTS

Co-culture of irradiated murine splenic lymphocytes with WJ-MSCs offered significant radioprotection to lymphocytes. WJ-MSC transplantation increased the homeostasis-driven proliferation of the lymphocytes. Neutralization of WJ-MSC conditioned medium with granulocyte-colony stimulating factor antibody abolished therapeutic radioprotection. Transcriptome analysis showed that WJ-MSCs share several common genes with bone marrow MSCs and embryonic stem cells and express high levels of unique genes such as interleukin (IL)1-α, IL1-β, IL-6, CXCL3, CXCL5, CXCL8, CXCL2, CCL2, FLT-1, and IL-33. It was also observed that WJ-MSCs preferentially modulate several cellular pathways and processes that handle the repair and regeneration of damaged tissues compared to stem cells from other sources. Cytokine-based network analysis showed that most of the radiosensitive tissues have a more complex network for the elevated cytokines.

CONCLUSION

Systemic infusion of WJ-MSC conditioned media will have significant potential for treating accidental radiation exposed victims.

A Double-Pronged Sword: XJB-5-131 Is a Suppressor of Somatic Instability and Toxicity in Huntington's Disease

Due to large increases in the elderly populations across the world, age-related diseases are expected to expand dramatically in the coming years. Among these, neurodegenerative diseases will be among the most devastating in terms of their emotional and economic impact on patients, their families, and associated subsidized health costs. There is no currently available cure or rescue for dying brain cells. Viable therapeutics for any of these disorders would be a breakthrough and provide relief for the large number of affected patients and their families. Neurodegeneration is accompanied by elevated oxidative damage and inflammation. While natural antioxidants have largely failed in clinical trials, preclinical phenotyping of the unnatural, mitochondrial targeted nitroxide, XJB-5-131, bodes well for further translational development in advanced animal models or in humans. Here we consider the usefulness of synthetic antioxidants for the treatment of Huntington's disease. The mitochondrial targeting properties of XJB-5-131 have great promise. It is both an electron scavenger and an antioxidant, reducing both somatic expansion and toxicity simultaneously through the same redox mechanism. By quenching reactive oxygen species, XJB-5-131 breaks the cycle between the rise in oxidative damage during disease progression and the somatic growth of the CAG repeat which depends on oxidation.

Oral Tongue Cancer in a Patient with Fanconi Anemia: A Case Report and Literature Review

Purpose

Fanconi anemia (FA) is a rare genetic disorder characterized by congenital anomalies, progressive bone marrow failure and high susceptibility to solid tumors, especially head and neck squamous cell carcinoma (HNSCC). Management of FA patients with head and neck cancer is a challenge due to increased risk of surgery, poor tolerance of chemotherapy, and severe myelotoxicity of radiotherapy.

Patients and Methods

We present a case of a 33-year-old man with carcinoma of oral tongue (T1N2M0), who experienced prolonged and profound bone marrow failure as a consequence of concurrent cisplatin/radiation. The young patient who developed HNSCC without risk factors, the myelotoxicity after exposure to platinum-based agent cisplatin and the further evaluation of phenotypic characteristics raised suspicion of FA. Whole exome sequencing performed for the patient and parents ultimately established the diagnosis of FA.

Results

Genetic testing in 23 FANC genes revealed two novel heterozygous mutations, c.367C>T and c.3971_3972delCGinsTT in FANCA gene of the patient, which were inherited from his father and mother, respectively. Radiotherapy with reduced dose has successfully alleviated the symptoms of tumor invasion and progression, and the radiation-related side effects were acceptable. Unfortunately, the patient eventually died of locoregional disease progression.

Conclusion

This case highlights the importance of considering the diagnosis of FA in young patients who develop HNSCC in the absence of risk factors, thus permitting more effective oncological treatment strategies and improved outcomes. In conclusion, any decision on different modalities of management in such patients should be based on a balance between locoregional control and therapeutic toxicity.

The mitochondrial-targeted reactive species scavenger JP4-039 prevents sulfite-induced alterations in antioxidant defenses, energy transfer, and cell death signaling in striatum of rats

Sulfite oxidase (SO) deficiency is a disorder caused either by isolated deficiency of SO or by defects in the synthesis of its molybdenum cofactor. It is characterized biochemically by tissue sulfite accumulation. Patients present with seizures, progressive neurological damage, and basal ganglia abnormalities, the pathogenesis of which is not fully established. Treatment is supportive and largely ineffective. To address the pathophysiology of sulfite toxicity, we examined the effects of intrastriatal administration of sulfite in rats on antioxidant defenses, energy transfer, and mitogen-activated protein kinases (MAPK) and apoptosis pathways in rat striatum. Sulfite administration decreased glutathione (GSH) concentration and glutathione peroxidase, glucose-6-phosphate dehydrogenase, glutathione S-transferase, and glutathione reductase activities in striatal tissue. Creatine kinase (CK) activity, a crucial enzyme for cell energy transfer, was also decreased by sulfite. Superoxide dismutase-1 (SOD1) and catalase (CAT) proteins were increased, while heme oxygenase-1 (HO-1) was decreased. Additionally, sulfite altered phosphorylation of MAPK by decreasing of p38 and increasing of ERK. Sulfite further augmented the content of GSK-3β, Bok, and cleaved caspase-3, indicating increased apoptosis. JP4-039 is a mitochondrial-targeted antioxidant that reaches higher intramitochondrial levels than other traditional antioxidants. Intraperitoneal injection of JP4-039 before sulfite administration preserved activity of antioxidant enzymes and CK. It also prevented or attenuated alterations in SOD1, CAT, and HO-1 protein content, as well as changes in p38, ERK, and apoptosis markers. In sum, oxidative stress and apoptosis induced by sulfite injection are prevented by JP4-039, identifying this molecule as a promising candidate for pharmacological treatment of SO-deficient patients.

Successful use of a therapeutic trial of graduated volume and dose escalation for postoperative head and neck radiotherapy in a Fanconi anemia patient

BACKGROUND

Patients with the heritable disease, Fanconi anemia (FA), have a 500-fold risk of developing head and neck squamous cell carcinomas (HNSCC). However, the use of conventional cytotoxic agents including radiation therapy and cisplatin-based chemotherapy is contraindicated in patients with FA due to underlying DNA repair defects.

METHODS/RESULTS

We present a young FA patient with recurrent HNSCC and high-risk pathologic features treated with a therapeutic trial of chemoradiation. This novel strategy employs a gentle radiation dose and volume escalation with concurrent pembrolizumab. The patient completed the entire course of therapy with no treatment delays or interruptions.

CONCLUSIONS

The FA patient population has a clear need for adjuvant treatment regimens given their predilection for HNSCC. A therapeutic trial may allow FA and other radiosensitive patients to trial radiation with the option to terminate treatment before any severe side effects occur and for some to complete a full course of treatment.

Mitochondrial energetics is impaired in very long-chain acyl-CoA dehydrogenase deficiency and can be rescued by treatment with mitochondria-targeted electron scavengers

Very long-chain acyl-CoA dehydrogenase (VLCAD) deficiency is the most common defect of mitochondrial long-chain fatty acid β-oxidation. Patients present with heterogeneous clinical phenotypes affecting heart, liver and skeletal muscle predominantly. The full pathophysiology of the disease is unclear and patient response to current therapeutic regimens is incomplete. To identify additional cellular alterations and explore more effective therapies, mitochondrial bioenergetics and redox homeostasis were assessed in VLCAD-deficient fibroblasts, and several protective compounds were evaluated. The results revealed cellular and tissue changes, including decreased respiratory chain (RC) function, increased reactive oxygen species (ROS) production and altered mitochondrial function and signaling pathways in a variety of VLCAD-deficient fibroblasts. The mitochondrially enriched electron and free radical scavengers JP4-039 and XJB-5-131 improved RC function and decreased ROS production significantly, suggesting that they are viable candidate compounds to further develop to treat VLCAD-deficient patients.

Fanconi Anemia Mouse Genotype-specific Mitigation of Total Body Irradiation by GS-Nitroxide JP4-039

BACKGROUND/AIM

Radiation mitigator, GS-nitroxide, JP4-039, was evaluated for mitigation of total body irradiation (TBI) in Fanconi anemia (FA) Fancd2-/- (129/Sv), Fancg-/- (B6), and Fanca-/- (129/Sv) mice.

MATERIALS AND METHODS

JP4-039 dissolved in 30% 2-hydroxypropyl-β-cyclodextrin was injected intramuscularly 24 h after total body irradiation (9.25 Gy) into Fanca-/-, Fancd2-/- and Fancg-/- mice. Irradiation survival curves were performed in vitro using bone marrow stromal cell lines derived from Fanca-/-, Fancd2-/- and Fancg-/- mice.

RESULTS

FA mice demonstrate genotype specific differences in TBI mitigation by JP4-039. Radiation effects in derived bone marrow stromal cell lines in vitro were mitigated by drugs that block apoptosis, but not necroptosis or ferroptosis.

CONCLUSION

FA mouse models are valuable for elucidating DNA repair pathways in cell and tissue responses to TBI, and the role of drugs that target distinct cell death pathways.

Amelioration of Mucositis in Proton Therapy of Fanconi Anemia Fanca-/- Mice by JP4-039

BACKGROUND/AIM

We tested JP4-039, a GS-nitroxide radiation damage mitigator in proton therapy of Fanconi anemia (FA) mice.

MATERIALS AND METHODS

Fanca-/- and Fanca+/+ bone marrow stromal cells were pre-treated with JP4-039 and irradiated with either protons or photons (0-10 GyRBE) followed by clonogenic survival and β-Galactosidase senescence analysis. Fanca-/- and Fanca+/+ mice were pretreated with JP4-039 for 10 min prior to oropharyngeal irradiation with either protons or photons (0 or 30 GyRBE) followed by sacrifice and measurement of oral cavity ulceration, distant hematopoietic suppression, and real-time polymerase chain reaction analysis.

RESULTS

JP4-039 reduced oral cavity ulceration in Fanca-/- mice, transcripts Nfkb, Ap1, Sp1, and Nrf2, and proton therapy induced distant marrow suppression.

CONCLUSION

JP4-039 protected Fanca-/- and Fanca+/+ cells and mouse oral cavity from both proton and photon radiation.

Evaluation of Different Formulations and Routes for the Delivery of the Ionizing Radiation Mitigator GS-Nitroxide (JP4-039)

BACKGROUND/AIM

The mitochondrial targeted GS-nitroxide, JP4-039, is an effective total body irradiation (TBI) mitigator when delivered intravenously (IV) up to 72 h after exposure. Effective systemic and localized administration to oral cavity/oropharynx and esophagus has been demonstrated. The objective of the study was to establish alternatives to IV administration suitable for JP4-039 delivery to mass casualties.

MATERIALS AND METHODS

JP4-039 was administered to C57BL/6 mice by topically applied carboxy-methyl-cellulose microneedle arrays (MNAs) or by intramuscular (IM) injection. Three different formulations that have passed Food and Drug Administration review, namely Captisol, 2-hydroxypropyl-β-cyclodextrin (cyclodextrin), and Miglyol-812-N, were used for drug delivery. Intraoral (IO) administration with each formulation was also evaluated.

RESULTS

All tested formulations and MNAs successfully delivered JP4-039. However, IM delivery of the Miglyol-812-N displayed very efficient and highly reproducible radiation mitigation.

CONCLUSION

Effective IM delivery of JP4-039 in animal models after TBI or partial-body irradiation suggested the use of the Miglyol-812-N formulation in both medical indications and radiation countermeasures.

Amelioration of Head and Neck Radiation-Induced Mucositis and Distant Marrow Suppression in Fanca-/- and Fancg-/- Mice by Intraoral Administration of GS-Nitroxide (JP4-039)

Squamous cell carcinomas of the head and neck are appearing with increased frequency in both marrow transplanted and non-transplanted Fanconi anemia (FA) patients. FA patients commonly display radiosensitivity of epithelial tissues, complicating effective radiotherapy. Fancd2^-/- mice (C57BL/6J and 129/Sv background) demonstrate epithelial tissue sensitivity to single-fraction or fractionated irradiation to the head and neck and distant marrow suppression (abscopal effect), both ameliorated by intraoral administration of the mitochondrial-targeted antioxidant, GS-nitroxide, JP4-039. We now report that mice of two other FA genotypes, Fancg^-/- (B6) and the most prevalent human genotype Fanca^-/- (129/Sv), also demonstrate: 1. reduced longevity of hematopoiesis in long-term bone marrow cultures; 2. radiosensitivity of bone marrow stromal cell lines; and 3. head and neck radiation-induced severe mucositis and abscopal suppression of distant marrow hematopoiesis. Intraoral administration of JP4-039/F15, but not non-mitochondrial-targeted 4-amino-Tempo/F15 or F15 alone, prior to each radiation treatment ameliorated both local and abscopal radiation effects. Head and neck irradiated TGF-β-resistant SMAD3^-/- (129/Sv) mice and double-knockout SMAD3^-/- Fancd2^-/- (129/Sv) mice treated daily with TGF-β receptor antagonist, LY364947, still displayed abscopal bone marrow suppression, implicating a non-TGF-β mechanism. Thus, amelioration of both local normal tissue radiosensitivity and distant marrow suppression by intraoral administration of JP4-039 in Fancg^-/- and Fanca^-/- mice supports a clinical trial of this locally administered normal tissue radioprotector and mitigator during head and neck irradiation in FA patients.

Evaluation of mitochondrial bioenergetics, dynamics, endoplasmic reticulum-mitochondria crosstalk, and reactive oxygen species in fibroblasts from patients with complex I deficiency

Mitochondrial complex I (CI) deficiency is the most frequent cause of oxidative phosphorylation (OXPHOS) disorders in humans. In order to benchmark the effects of CI deficiency on mitochondrial bioenergetics and dynamics, respiratory chain (RC) and endoplasmic reticulum (ER)-mitochondria communication, and superoxide production, fibroblasts from patients with mutations in the ND6, NDUFV1 or ACAD9 genes were analyzed. Fatty acid metabolism, basal and maximal respiration, mitochondrial membrane potential, and ATP levels were decreased. Changes in proteins involved in mitochondrial dynamics were detected in various combinations in each cell line, while variable changes in RC components were observed. ACAD9 deficient cells exhibited an increase in RC complex subunits and DDIT3, an ER stress marker. The level of proteins involved in ER-mitochondria communication was decreased in ND6 and ACAD9 deficient cells. |ΔΨ| and cell viability were further decreased in all cell lines. These findings suggest that disruption of mitochondrial bioenergetics and dynamics, ER-mitochondria crosstalk, and increased superoxide contribute to the pathophysiology in patients with ACAD9 deficiency. Furthermore, treatment of ACAD9 deficient cells with JP4-039, a novel mitochondria-targeted reactive oxygen species, electron and radical scavenger, decreased superoxide level and increased basal and maximal respiratory rate, identifying a potential therapeutic intervention opportunity in CI deficiency.

Effectiveness of Analogs of the GS-Nitroxide, JP4-039, as Total Body Irradiation Mitigators

BACKGROUND/AIM

Mitochondrial-targeted gramicidin S (GS)-nitroxide, JP4-039, has been demonstrated to be a potent radiation mitigator, and safe over a wide dose range. In addition, JP4-039 has organ-specific effectiveness when locally applied.

MATERIALS AND METHODS

We tested the effect of another GS-nitroxide, XJB-5-131, which has more effective mitochondrial localization, and compared these results to those for radiation mitigation against the hematopoietic syndrome, and two analogs of JP4-039, which have the same mitochondrial localization signal, but different chemical payloads: JRS527.084 contains a second nitroxide per molecule, and TK649.030 contains an ester group attached to the nitroxide.

RESULTS

The results demonstrate the superiority of JP4-039 as a systemic radiation mitigator.

CONCLUSION

Structure-activity relationships and bioassays demonstrate that JP4-039 is an optimized small-molecule radiation mitigator.

FANCD2 protects against bone marrow injury from ferroptosis

Bone marrow injury remains a serious concern in traditional cancer treatment. Ferroptosis is an iron- and oxidative-dependent form of regulated cell death that has become part of an emerging strategy for chemotherapy. However, the key regulator of ferroptosis in bone marrow injury remains unknown. Here, we show that Fanconi anemia complementation group D2 (FANCD2), a nuclear protein involved in DNA damage repair, protects against ferroptosis-mediated injury in bone marrow stromal cells (BMSCs). The classical ferroptosis inducer erastin remarkably increased the levels of monoubiquitinated FANCD2, which in turn limited DNA damage in BMSCs. FANCD2-deficient BMSCs were more sensitive to erastin-induced ferroptosis (but not autophagy) than FANCD2 wild-type cells. Knockout of FANCD2 increased ferroptosis-associated biochemical events (e.g., ferrous iron accumulation, glutathione depletion, and malondialdehyde production). Mechanically, FANCD2 regulated genes and/or expression of proteins involved in iron metabolism (e.g., FTH1, TF, TFRC, HAMP, HSPB1, SLC40A1, and STEAP3) and lipid peroxidation (e.g., GPX4). Collectively, these findings indicate that FANCD2 plays a novel role in the negative regulation of ferroptosis. FANCD2 could represent an amenable target for the development of novel anticancer therapies aiming to reduce the side effects of ferroptosis inducers.

A Topical Mitochondria-Targeted Redox-Cycling Nitroxide Mitigates Oxidative Stress-Induced Skin Damage

Skin is the largest human organ, and it provides a first line of defense that includes physical, chemical, and immune mechanisms to combat environmental stress. Radiation is a prevalent environmental stressor. Radiation-induced skin damage ranges from photoaging and cutaneous carcinogenesis caused by UV exposure, to treatment-limiting radiation dermatitis associated with radiotherapy, to cutaneous radiation syndrome, a frequently fatal consequence of exposures from nuclear accidents. The major mechanism of skin injury common to these exposures is radiation-induced oxidative stress. Efforts to prevent or mitigate radiation damage have included development of antioxidants capable of reducing reactive oxygen species. Mitochondria are particularly susceptible to oxidative stress, and mitochondrial-dependent apoptosis plays a major role in radiation-induced tissue damage. We reasoned that targeting a redox cycling nitroxide to mitochondria could prevent reactive oxygen species accumulation, limiting downstream oxidative damage and preserving mitochondrial function. Here we show that in both mouse and human skin, topical application of a mitochondrially targeted antioxidant prevents and mitigates radiation-induced skin damage characterized by clinical dermatitis, loss of barrier function, inflammation, and fibrosis. Further, damage mitigation is associated with reduced apoptosis, preservation of the skin's antioxidant capacity, and reduction of irreversible DNA and protein oxidation associated with oxidative stress.

Evolution of malignant plasmacytoma cell lines from K14E7 Fancd2-/- mouse long-term bone marrow cultures

We tested the effect of expression of the Human Papilloma Virus (HPV E7) oncogene on hematopoiesis in long-term bone marrow cultures (LTBMCs) derived from K14E7 (FVB) Fancd2-/- (129/Sv), K14E7 Fancd2+/+, Fancd2-/-, and control (FVB X 129/Sv) Fl mice. K14E7 Fancd2-/- and Fancd2-/- LTBMCs showed decreased duration of production of total nonadherent hematopoietic cells and progenitors forming day 7 and day 14 multilineage CFU-GEMM colonies in secondary cultures (7 wks and 8 wks respectively) compared to cultures from K14E7 Fancd2+/+ (17 wks) or control mice (18 wks) p < 0.0001. Marrow stromal cell lines derived from both K14E7 Fancd2-/- and Fancd2-/- cultures were radiosensitive, as were IL-3 dependent hematopoietic progenitor cell lines derived from K14E7 Fancd2-/- cultures. In contrast, Fancd2-/- mouse hematopoietic progenitor cell lines and fresh marrow were radioresistant. K14E7 Fancd2-/- mouse freshly explanted bone marrow expressed no detectable K14 or E7; however, LTBMCs produced K14 positive factor-independent (FI) clonal malignant plasmacytoma forming cell lines in which E7 was detected in the nucleus with p53 and Rb. Transfection of an E6/E7 plasmid into Fancd2-/-, but not control Fancd2+/+ IL-3 dependent hematopoietic progenitor cell lines, increased cloning efficiency, cell growth, and induced malignant cell lines. Therefore, the altered radiobiology of hematopoietic progenitor cells and malignant transformation in vitro by K14E7 expression in cells of the Fancd2-/- genotype suggests a potential role of HPV in hematopoietic malignancies in FA patients.

Intraoral Mitochondrial-Targeted GS-Nitroxide, JP4-039, Radioprotects Normal Tissue in Tumor-Bearing Radiosensitive Fancd2(-/-) (C57BL/6) Mice

We evaluated normal tissue specific radioprotection of the oral cavity in radiosensitive Fanconi Anemia (FA) Fancd2(-/-) mice with orally established tumors using mitochondrial-targeted GS-nitroxide (JP4-039). Adult (10-12 weeks old) Fancd2(+/+), Fancd2(+/-) and Fancd2(-/-) mice (C57BL/6 background) and subgroups with orally established TC-1 epithelial cell tumors received a single fraction of 28 Gy or four daily fractions of 8 Gy to the head and neck. Subgroups received JP4-039 in F15 emulsion (F15/JP4-039; 0.4 mg/mouse), 4-amino-Tempo in F15 emulsion (F15/4-amino-Tempo; 0.2 mg/mouse) or F15 emulsion alone prior to each irradiation. Oral mucosa of Fancd2(-/-) mice showed baseline elevated RNA transcripts for Sod2, p53, p21 and Rad51 (all P < 0.0012) and suppressed levels of Nfkb and Tgfb, (all P < 0.0020) compared with Fancd2(+/+) mice. The oral mucosa in tumor-bearing mice of all genotypes showed decreased levels of p53 and elevated Tgfb and Gadd45a (P ≤ 0.0001 for all three genotypes). Intraoral F15/JP4-039, but not F15/4-amino-Tempo, modulated radiation-induced normal tissue transcript elevation, ameliorated mucosal ulceration and reduced the depletion of antioxidant stores in oral cavity tissue of all genotypes, but did not radioprotect tumors. Mitochondrial targeting makes F15/JP4-039 an effective normal tissue radioprotector for Fancd2(-/-) mice, as well as wild-type mice.

Oxidative Stress -a Phenotypic Hallmark of Fanconi Anemia and Down Syndrome: The Effect of Antioxidants

Background:

Oxidative stress plays a major role in the pathogenesis of leukemia-prone diseases such as Fanconi anemia (FA) and Down syndrome (DS)

Aim:

To explore the oxidative stress state in children with DS and FA by estimating the levels of antioxidants (e.g., malondialdehyde [MDA], total antioxidant capacity, and superoxide dismutase [SOD] activity) and DNA damage, and to evaluate of the effect of antioxidant treatment on these patients.

Subjects and methods

The study included 32 children clinically diagnosed with (15 patients) and FA (17 patients) in addition to 17 controls matched for age and sex. MDA, total antioxidant capacity, SOD activity, and DNA damage were measured. Antioxidants including Vitamin A, E, and C were given to the patients according to the recommended daily allowance for 6 months. Clinical follow-up and re-evaluation were conducted for all patients. Laboratory tests including complete blood count, karyotyping, DNA damage, and oxidative stress were re-evaluated. Statistical analysis was performed using statistical computer program Statistical Package for the Social Sciences version 14.0.

Results:

Children with FA and DS had elevated levels of oxidative stress and more DNA damage than controls. Oxidative stress parameters and DNA damage improved in FA and DS patients after antioxidant administration.

Conclusion:

Early administration of antioxidants to FA and DS patients is recommended for slowing of the disease course with symptoms amelioration and improvement of general health.

Activation of the Fanconi anemia/BRCA pathway at low doses of ionization radiation

Fanconi anemia (FA) is a rare, clinically heterogeneous autosomal recessive or X-linked genetic disease characterized by chromosome fragility, congenital malformations and cancer susceptibility. FA patients are usually radiosensitive when exposed to radiotherapy but the role of the FA in response to ionizing radiation (IR) is controversial. Here we have investigated IR-induced activation of the FA pathway by systematically analyzing monoubiquitination of the central protein FANCD2 and subsequent recruitment to stalled replication forks in primary fibroblasts. We developed an immunolabelling method to simultaneously visualize IR-induced FANCD2 and γH2AX foci in S-phase. We observed FANCD2 foci formation in a subset of IR-induced γH2AX foci in S-phase cells. This was observed at doses of IR ranging from 0.1 to 5.0Gy in a dose dependent non-threshold fashion. Our results indicate that minimum doses of IR can produce replication fork stalling and FA pathway activation during S-phase in primary cells.

Antioxidant Approaches to Management of Ionizing Irradiation Injury

Ionizing irradiation induces acute and chronic injury to tissues and organs. Applications of antioxidant therapies for the management of ionizing irradiation injury fall into three categories: (1) radiation counter measures against total or partial body irradiation; (2) normal tissue protection against acute organ specific ionizing irradiation injury; and (3) prevention of chronic/late radiation tissue and organ injury. The development of antioxidant therapies to ameliorate ionizing irradiation injury began with initial studies on gene therapy using Manganese Superoxide Dismutase (MnSOD) transgene approaches and evolved into applications of small molecule radiation protectors and mitigators. The understanding of the multiple steps in ionizing radiation-induced cellular, tissue, and organ injury, as well as total body effects is required to optimize the use of antioxidant therapies, and to sequence such approaches with targeted therapies for the multiple steps in the irradiation damage response.

Improved hematopoiesis in GS-nitroxide (JP4-039)-treated mouse long-term bone marrow cultures and radioresistance of derived bone marrow stromal cell lines

AIM

To determine if the small-molecule radioprotector GS-nitroxide, JP4-039, improved hematopoiesis in long-term bone marrow cultures (LTBMCs), explanted marrow from in vivo drug-treated C57BL/6NTac mice was maintained in JP4-039 for 25 weeks. Hematopoietic cell production and radiobiology of derived stromal cell lines was measured.

MATERIALS AND METHODS

Groups of LTBMCs were established from mouse groups. Stromal cell lines were established from the adherent layer of JP4-039-treated and untreated control groups.

RESULTS

LTBMCs maintained in JP4-039 exhibited increased production of total non-adherent and 7-day and 14-day hematopoietic colony-forming cells. Stromal cell lines derived from JP4-039-treated cultures were radioresistant in vitro, demonstrated a distinct squamous/epithelial morphology and overexpressed Nrf2, Ctgf, Lox, Tlr1, collagen 1a, Brd3, and Brd4.

CONCLUSION

Chronic treatment of bone marrow cultures and derived stromal cell lines with JP4-039 was non-toxic, and conferred resistance to oxidative stress.

Effect of lentinan on membrane-bound protein expression in splenic lymphocytes under chronic low-dose radiation

We investigated the protective effects of lentinan against damages to chronic and low-dose radiation (CL-radiation) by using mouse models. The mice were randomized divided into four groups: normal control mice (Ctr), mice exposed to radiation (Rad), irradiated mice treated with low-dose lentinan (0.1mg/(kg.d), RL), and irradiated mice treated with high-dose lentinan (0.5mg/(kg.d), RH). All the mice were injected intraperitoneally once a day at a dose of 0.5mL (Ctr and Rad with normal sodium while RL and RH with lentinan). The success of radiation models was confirmed by HE stain and cell morphology by a transmission electron microscope (TEM). On the basis of radiation models, we investigated the expression of proteins on the membrane of splenic cells through MALDI-TOF-MS/MS. The results demonstrated that both RT-radiation and lentinan affected the expression of membrane proteins, but lentinan protected the splenic cells and tissue from the injuries caused by CL-radiation. Therefore, we speculated that CL-radiation mainly damages the genetic materials and membrane-bound proteins, while lentinan protects membrane-bound proteins by regulating signal transduction and the appearance of the cells.

Amelioration of radiation-induced oral cavity mucositis and distant bone marrow suppression in fanconi anemia Fancd2-/- (FVB/N) mice by intraoral GS-nitroxide JP4-039

The altered DNA damage response pathway in patients with Fanconi anemia (FA) may increase the toxicity of clinical radiotherapy. We quantitated oral cavity mucositis in irradiated Fanconi anemia Fancd2(-/-) mice, comparing this to Fancd2(+/-) and Fancd2(+/+) mice, and we measured distant bone marrow suppression and quantitated the effect of the intraoral radioprotector GS-nitroxide, JP4-039 in F15 emulsion. We found that FA mice were more susceptible to radiation injury and that protection from radiation injury by JP4-039/F15 was observed at all radiation doses. Adult 10-12-week-old mice, of FVB/N background Fancd2(-/-), Fancd2(+/-) and Fancd2(+/+) were head and neck irradiated with 24, 26, 28 or 30 Gy (large fraction sizes typical of stereotactic radiosurgery treatments) and subgroups received intraoral JP4-039 (0.4 mg/mouse in 100 μL F15 liposome emulsion) preirradiation. On day 2 or 5 postirradiation, mice were sacrificed, tongue tissue and femur marrow were excised for quantitation of radiation-induced stress response, inflammatory and antioxidant gene transcripts, histopathology and assay for femur marrow colony-forming hematopoietic progenitor cells. Fancd2(-/-) mice had a significantly higher percentage of oral mucosal ulceration at day 5 after 26 Gy irradiation (59.4 ± 8.2%) compared to control Fancd2(+/+) mice (21.7 ± 2.9%, P = 0.0063). After 24 Gy irradiation, Fancd2(-/-) mice had a higher oral cavity percentage of tongue ulceration compared to Fancd2(+/+) mice irradiated with higher doses of 26 Gy (P = 0.0123). Baseline and postirradiation oral cavity gene transcripts were altered in Fancd2(-/-) mice compared to Fancd2(+/+) controls. Fancd2(-/-) mice had decreased baseline femur marrow CFU-GM, BFUe and CFU-GEMM, which further decreased after 24 or 26 Gy head and neck irradiation. These changes were not seen in head- and neck-irradiated Fancd2(+/+) mice. In radiosensitive Fancd2(-/-) mice, biomarkers of both local oral cavity and distant marrow radiation toxicity were ameliorated by intraoral JP4-039/F15. We propose that Fancd2(-/-) mice are a valuable radiosensitive animal model system, which can be used to evaluate potential radioprotective agents.

Esophageal radioprotection by swallowed JP4-039/F15 in thoracic-irradiated mice with transgenic lung tumors

BACKGROUND/AIM

To determine whether Gramicidin S (GS)-nitroxide, JP4-039, esophageal radiation protection protected lung tumors in a transgenic model, LoxP-Stoop-LoxP Kristen Rat Sarcoma Viral oncogene (LSL-K-RAS) mice were administered intra-tracheal- Carbapenem-resistant Enterobacteriaceae (CRE) recombinase, bilateral lung tumors were confirmed at 11 weeks, then thoracic irradiation was delivered.

MATERIALS AND METHODS

Mice received single-fraction 15 Gy or 24 Gy to both lungs, in subgroups receiving intraesophageal administration 10 min before irradiation of JP4-039 (in F15 emulsion) tumor size reduction and survival were investigated. Mice were followed for survival, and reduction in tumor size.

RESULTS

There was no evidence of tumor radioprotection in mice receiving JP4-039/F15.

CONCLUSION

Intraesophageal radioprotective small-molecule antioxidant therapy protects normal tissue but not tumor tissue in mice with transgenic lung tumors.

Effects of the bifunctional sulfoxide MMS350, a radiation mitigator, on hematopoiesis in long-term bone marrow cultures and on radioresistance of marrow stromal cell lines

The ionizing irradiation mitigator MMS350 prolongs survival of mice treated with total-body irradiation and prevents radiation-induced pulmonary fibrosis when added to drinking water at day 100 after thoracic irradiation. The effects of MMS350 on hematopoiesis in long-term bone marrow culture and on the radiobiology of derived bone marrow stromal cell lines were tested. Long-term bone marrow cultures were established from C57BL/6NTac mice and maintained in a high-humidity incubator, with 7% CO2 and the addition of 100 μM MMS350 at the weekly media change. Over 10 weeks in culture, MMS350 had no significant effect on maintenance of hematopoietic stem cell production, or on nonadherent cells or colony-forming units of hematopoietic progenitor cells. Stromal cell lines derived from non MMS350-treated long-term cultures or control stromal cells treated with MMS350 were radioresistant in the clonogenic survival curve assay. MMS350 is a non-toxic, highly water-soluble radiation mitigator that exhibits radioprotective effects on bone marrow stromal cells.

Can Radiosensitivity Associated with Defects in DNA Repair be Overcome by Mitochondrial-Targeted Antioxidant Radioprotectors

Radiation oncologists have observed variation in normal tissue responses between patients in many instances with no apparent explanation. The association of clinical tissue radiosensitivity with specific genetic repair defects (Wegner's syndrome, Ataxia telangiectasia, Bloom's syndrome, and Fanconi anemia) has been well established, but there are unexplained differences between patients in the general population with respect to the intensity and rapidity of appearance of normal tissue toxicity including radiation dermatitis, oral cavity mucositis, esophagitis, as well as differences in response of normal tissues to standard analgesic or other palliative measures. Strategies for the use of clinical radioprotectors have included modalities designed to either prevent and/or palliate the consequences of radiosensitivity. Most prominently, modification of total dose, fraction size, or total time of treatment delivery has been necessary in many patients, but such modifications may reduce the likelihood of local control and/or radiocurability. As a model system in which to study potential radioprotection by mitochondrial-targeted antioxidant small molecules, we have studied cell lines and tissues from Fanconi anemia (Fancd2(-/-)) mice of two background strains (C57BL/6NHsd and FVB/N). Both were shown to be radiosensitive with respect to clonogenic survival curves of bone marrow stromal cells in culture and severity of oral cavity mucositis during single fraction or fractionated radiotherapy. Oral administration of the antioxidant GS-nitroxide, JP4-039, provided significant radioprotection, and also ameliorated distant bone marrow suppression (abscopal effect of irradiation) in Fancd2 (-/-) mice. These data suggest that radiation protection by targeting the mitochondria may be of therapeutic benefit even in the setting of defects in the DNA repair process for irradiation-induced DNA double strand breaks.

Radiologic differences between bone marrow stromal and hematopoietic progenitor cell lines from Fanconi Anemia (Fancd2(-/-)) mice

FancD2 plays a central role in the human Fanconi anemia DNA damage response (DDR) pathway. Fancd2(-/-) mice exhibit many features of human Fanconi anemia including cellular DNA repair defects. Whether the DNA repair defect in Fancd2(-/-) mice results in radiologic changes in all cell lineages is unknown. We measured stress of hematopoiesis in long-term marrow cultures and radiosensitivity in clonogenic survival curves, as well as comet tail intensity, total antioxidant stores and radiation-induced gene expression in hematopoietic progenitor compared to bone marrow stromal cell lines. We further evaluated radioprotection by a mitochondrial-targeted antioxidant GS-nitroxide, JP4-039. Hematopoiesis longevity in Fancd2(-/-) mouse long-term marrow cultures was diminished and bone marrow stromal cell lines were radiosensitive compared to Fancd2(+/+) stromal cells (Fancd2(-/-) D0 = 1.4 ± 0.1 Gy, ñ = 5.0 ± 0.6 vs. Fancd2(+/+) D0 = 1.6 ± 0.1 Gy, ñ = 6.7 ± 1.6), P = 0.0124 for D0 and P = 0.0023 for ñ, respectively). In contrast, Fancd2(-/-) IL-3-dependent hematopoietic progenitor cells were radioresistant (D0 = 1.71 ± 0.04 Gy and ñ = 5.07 ± 0.52) compared to Fancd2(+/+) (D0 = 1.39 ± 0.09 Gy and ñ = 2.31 ± 0.85, P = 0.001 for D0). CFU-GM from freshly explanted Fancd2(-/-) marrow was also radioresistant. Consistent with radiosensitivity, irradiated Fancd2(-/-) stromal cells had higher DNA damage by comet tail intensity assay compared to Fancd2(+/+) cells (P < 0.0001), slower DNA damage recovery, lower baseline total antioxidant capacity, enhanced radiation-induced depletion of antioxidants, and increased CDKN1A-p21 gene transcripts and protein. Consistent with radioresistance, Fancd2(-/-) IL-3-dependent hematopoietic cells had higher baseline and post irradiation total antioxidant capacity. While, there was no detectable alteration of radiation-induced cell cycle arrest with Fancd2(-/-) stromal cells, hematopoietic progenitor cells showed reduced G2/M cell cycle arrest. The absence of the mouse Fancd2 gene product confers radiosensitivity to bone marrow stromal but not hematopoietic progenitor cells.

The impact of ionizing radiation on placental trophoblasts

INTRODUCTION

Exposure to low-dose radiation is widespread and attributable to natural sources. However, occupational, medical, accidental, and terrorist-related exposures remain a significant threat. Information on radiation injury to the feto-placental unit is scant and largely observational. We hypothesized that radiation causes trophoblast injury, and alters the expression of injury-related transcripts in vitro or in vivo, thus affecting fetal growth.

METHODS

Primary human trophoblasts (PHTs), BeWo or NCCIT cells were irradiated in vitro, and cell number and viability were determined. Pregnant C57Bl/6HNsd mice were externally irradiated on E13.5, and placentas examined on E17.5. RNA expression was analyzed using microarrays and RT-qPCR. The experiments were repeated in the presence of the gramicidin S (GS)-derived nitroxide JP4-039, used to mitigate radiation-induced cell injury.

RESULTS

We found that survival of in vitro-irradiated PHT cell was better than that of irradiated BeWo trophoblast cell line or the radiosensitive NCCIT mixed germ cell tumor line. Radiation altered the expression of several trophoblast genes, with a most dramatic effect on CDKN1A (p21, CIP1). Mice exposed to radiation at E13.5 exhibited a 25% reduction in mean weight by E17.5, and a 9% reduction in placental weight, which was associated with relatively small changes in placental gene expression. JP4-039 had a minimal effect on feto-placental growth or on gene expression in irradiated PHT cells or mouse placenta.

DISCUSSION AND CONCLUSION

While radiation affects placental trophoblasts, the established placenta is fairly resistant to radiation, and changes in this tissue may not fully account for fetal growth restriction induced by ionizing radiation.

Synthesis of analogs of the radiation mitigator JP4-039 and visualization of BODIPY derivatives in mitochondria

JP4-039 is a lead structure in a series of nitroxide conjugates that are capable of accumulating in mitochondria and scavenging reactive oxygen species (ROS). To explore structure-activity relationships (SAR), new analogs with variable nitroxide moieties were prepared. Furthermore, fluorophore-tagged analogs were synthesized and provided the opportunity for visualization in mitochondria. All analogs were tested for radioprotective and radiomitigative effects in 32Dcl3 cells.

Radioresistance of bone marrow stromal and hematopoietic progenitor cell lines derived from Nrf2-/- homozygous deletion recombinant-negative mice

AIM

We determined whether bone marrow from Nrf2(-/-) compared with Nrf2(+/+) mice differed in response to the oxidative stress of continuous marrow culture, and in radiosensitivity of derived stromal and interleukin-3 (IL-3)-dependent hematopoietic progenitor cells.

MATERIALS AND METHODS

Hematopoiesis longevity in Nrf2(-/-) was compared with Nrf2(+/+) mice in long-term bone marrow cultures. Clonogenic irradiation survival curves were performed on derived cell lines. Total antioxidant capacity at baseline in nonirradiated cells and at 24 hours after 5 Gy and 10 Gy irradiation was quantitated using an antioxidant reductive capacity assay.

RESULTS

Long-term cultures of bone marrow from Nrf2(-/-) compared to Nrf2(+/+) mice demonstrated equivalent longevity of production of total cells and hematopoietic progenitor cells forming multi-lineage hematopoietic colonies over 26 weeks in culture. Both bone marrow stromal cell lines and Il-3-dependent hematopoietic progenitor cell lines derived from Nrf2(-/-) mouse marrow cultures were radioresistant compared to Nrf2(+/+)-derived cell lines. Both DNA repair assay and total antioxidant capacity assay showed no defect in Nrf2(-/-) compared to Nrf2(+/+) stromal cells and IL-3-dependent cells.

CONCLUSION

The absence of a functional Nrf2 gene product does not alter cellular interactions in continuous marrow culture, nor response to dsDNA damage repair and antioxidant response. However, lack of the Nrf2 gene does confer radioresistance on marrow stromal and hematopoietic cells.

Evaluation of potential ionizing irradiation protectors and mitigators using clonogenic survival of human umbilical cord blood hematopoietic progenitor cells

We evaluated the use of colony formation (colony-forming unit-granulocyte macrophage [CFU-GM], burst-forming unit erythroid [BFU-E], and colony-forming unit-granulocyte-erythroid-megakaryocyte-monocytes [CFU-GEMM]) by human umbilical cord blood (CB) hematopoietic progenitor cells for testing novel small molecule ionizing irradiation protectors and mitigators. The following compounds were added before (protection) or after (mitigation) ionizing irradiation: GS-nitroxides (JP4-039 and XJB-5-131), the bifunctional sulfoxide MMS-350, the phosphoinositol-3-kinase inhibitor LY29400, triphenylphosphonium-imidazole fatty acid, the nitric oxide synthase inhibitor (MCF-201-89), the p53/mdm2/mdm4 inhibitor (BEB55), methoxamine, isoproterenol, propranolol, and the adenosine triphosphate-sensitive potassium channel blocker (glyburide). The drugs XJB-5-131, JP4-039, and MMS-350 were radiation protectors for CFU-GM. JP4-039 was also a radiation protector for CFU-GEMM. The drugs XJB-5-131, JP4-039, and MMS-350 were radiation mitigators for BFU-E, MMS-350 and JP4-039 were mitigators for CFU-GM, and MMS350 was a mitigator for CFU-GEMM. In contrast, other drugs were effective in murine assays; TTP-IOA, LY294002, MCF201-89, BEB55, propranolol, isoproterenol, methoxamine, and glyburide but showed no significant protection or mitigation in human CB assays. These data support the testing of new candidate clinical radiation protectors and mitigators using human CB clonogenic assays early in the drug discovery process, thus reducing the need for animal experiments.

Increased longevity of hematopoiesis in continuous marrow cultures and radiation resistance of marrow stromal and hematopoietic progenitor cells from caspase-1 homozygous recombinant-negative (knockout) mice

AIM

We determined whether absence of caspase-1 altered the stress response of hematopoietic and bone marrow stromal cells in vitro.

MATERIALS AND METHODS

Long-term bone marrow cultures from caspase-1 -/- and control caspase-1 +/+ mice were established and the derived bone marrow stromal and interleukin-3 (Il-3)-dependent hematopoietic progenitor cell lines were evaluated for radiosensitivity.

RESULTS

Long-term bone marrow cultures from caspase-1 -/- mice generated hematopoietic cells for over 30 weeks in vitro, significantly longer than controls did (p=0.0018). Bone marrow stromal (mesenchymal stem cell) and Il-3-dependent hematopoietic progenitor cell lines from caspase-1-/- marrow cultures compared to caspase-1 +/+ were radioresistant (p=0.0486 and p=0.0235 respectively). Total-body irradiated caspase-1 -/- mice were not significantly radioresistant compared to controls (p=0.6542).

CONCLUSION

Caspase-1 deletion increases hematopoiesis and radioresistance of bone marrow cells in vitro.

Why otolaryngologists need to be aware of Fanconi anemia

Fanconi anemia (FA) is a rare disorder inherited in an autosomal recessive fashion, with an estimated incidence of 1:360,000 births. Although hematologic complications are the most common manifestation of this disease, cancers, especially of the head and neck, are also prominent. The chromosomal fragility of patients with FA necessitates careful planning of therapy and monitoring, and awareness of this rare disorder is crucial to recognizing it in the clinic.

Strategies for discovery of small molecule radiation protectors and radiation mitigators

Mitochondrial targeted radiation damage protectors (delivered prior to irradiation) and mitigators (delivered after irradiation, but before the appearance of symptoms associated with radiation syndrome) have been a recent focus in drug discovery for (1) normal tissue radiation protection during fractionated radiotherapy, and (2) radiation terrorism counter measures. Several categories of such molecules have been discovered: nitroxide-linked hybrid molecules, including GS-nitroxide, GS-nitric oxide synthase inhibitors, p53/mdm2/mdm4 inhibitors, and pharmaceutical agents including inhibitors of the phosphoinositide-3-kinase pathway and the anti-seizure medicine, carbamazepine. Evaluation of potential new radiation dose modifying molecules to protect normal tissue includes: clonogenic radiation survival curves, assays for apoptosis and DNA repair, and irradiation-induced depletion of antioxidant stores. Studies of organ specific radioprotection and in total body irradiation-induced hematopoietic syndrome in the mouse model for protection/mitigation facilitate rational means by which to move candidate small molecule drugs along the drug discovery pipeline into clinical development.