Efficacy of superoxide dismutase mimetic M40403 in attenuating radiation-induced oral mucositis in hamsters

Balanced Duality: H2O2-Based Therapy in Cancer and Its Protective Effects on Non-Malignant Tissues

Conventional cancer therapy strategies, although centered around killing tumor cells, often lead to severe side effects on surrounding normal tissues, thus compromising the chronic quality of life in cancer survivors. Hydrogen peroxide (H2O2) is a secondary signaling molecule that has an array of functions in both tumor and normal cells, including the promotion of cell survival pathways and immune cell modulation in the tumor microenvironment. H2O2 is a reactive oxygen species (ROS) crucial in cellular homeostasis and signaling (at concentrations maintained under nM levels), with increased steady-state levels in tumors relative to their normal tissue counterparts. Increased steady-state levels of H2O2 in tumor cells, make them vulnerable to oxidative stress and ultimately, cell death. Recently, H2O2-producing therapies-namely, pharmacological ascorbate and superoxide dismutase mimetics-have emerged as compelling complementary treatment strategies in cancer. Both pharmacological ascorbate and superoxide dismutase mimetics can generate excess H2O2 to overwhelm the impaired H2O2 removal capacity of cancer cells. This review presents an overview of H2O2 metabolism in the physiological and malignant states, in addition to discussing the anti-tumor and normal tissue-sparing mechanism(s) of, and clinical evidence for, two H2O2-based therapies, pharmacological ascorbate and superoxide dismutase mimetics.

Superoxide Dismutase Mimetic Avasopasem Manganese Enhances Radiation Therapy Effectiveness in Soft Tissue Sarcomas and Accelerates Wound Healing

Soft tissue sarcomas (STSs) are mesenchymal malignant lesions that develop in soft tissues. Despite current treatments, including radiation therapy (RT) and surgery, STSs can be associated with poor patient outcomes and metastatic recurrences. Neoadjuvant radiation therapy (nRT), while effective, is often accompanied by severe postoperative wound healing complications due to damage to the surrounding normal tissues. Thus, there is a need to develop therapeutic approaches to reduce nRT toxicities. Avasopasem manganese (AVA) is a selective superoxide dismutase mimetic that protects against IR-induced oral mucositis and lung fibrosis. We tested the efficacy of AVA in enhancing RT in STSs and in promoting wound healing. Using colony formation assays and alkaline comet assays, we report that AVA selectively enhanced the STS (liposarcoma, fibrosarcoma, leiomyosarcoma, and MPNST) cellular response to radiation compared to normal dermal fibroblasts (NDFs). AVA is believed to selectively enhance radiation therapy by targeting differential hydrogen peroxide clearance in tumor cells compared to non-malignant cells. STS cells demonstrated increased catalase protein levels and activity compared to normal fibroblasts. Additionally, NDFs showed significantly higher levels of GPx1 activity compared to STSs. The depletion of glutathione using buthionine sulfoximine (BSO) sensitized the NDF cells to AVA, suggesting that GPx1 may, in part, facilitate the selective toxicity of AVA. Finally, AVA significantly accelerated wound closure in a murine model of wound healing post RT. Our data suggest that AVA may be a promising combination strategy for nRT therapy in STSs.

Avasopasem for the treatment of radiotherapy-induced severe oral mucositis

INTRODUCTION

Oral mucositis (OM) remains a significant, highly symptomatic, disruptive side effect of radiation and concomitant chemoradiation therapy used for the treatment of squamous cell cancers of the head and neck. Despite its clinical and economic burden, implementation of an effective intervention has been elusive.

AREAS COVERED

Increased understanding of the complexity of the biological basis for its pathogenesis has yielded potential druggable targets of such as the mitigation of superoxide formation and oxidative stress. Avasopasem manganese is a selective superoxide dismutase mimetic being developed by Galera Therapeutics, which recently submitted a New Drug Application (NDA) to the FDA for a severe OM indication. This review describes the preclinical and clinical studies which led to, and supported the NDA, and assesses the potential utility of avasopasem clinically.

EXPERT OPINION

Avasopasem manganese appears to effectively mitigate severe OM associated with concomitant chemoradiation used in the treatment of head and neck cancers, as well as cisplatin-associated renal toxicity in the absence of impairing tumor response.

Rodent models for anticancer toxicity studies: contributions to drug development and future perspectives

Antineoplastic treatment induces a type of gastrointestinal toxicity known as mucositis. Findings in animal models are usually easily reproducible, and standardized treatment regimens are often used, thus supporting translational science. Essential characteristics of mucositis, including intestinal permeability, inflammation, immune and oxidative responses, and tissue repair mechanisms, can be easily investigated in these models. Given the effects of mucositis on the quality of life of patients with cancer, and the importance of experimental models in the development of more effective new therapeutic alternatives, this review discusses progress and current challenges in using experimental models of mucositis in translational pharmacology research. Teaser Experimental models for studying gastrointestinal mucositis have provided a wealth of information improving the understanding of antineoplastic toxicity.

Radiotherapy-induced severe oral mucositis: pharmacotherapies in recent and current clinical trials

INTRODUCTION

Oral mucositis (OM) is among the most common, damaging side effects of head and neck radiation therapy and may interfere with patients' ability to comply with optimal treatment.

AREAS COVERED

The increasing unmet clinical need, recent clinical trial successes, and the commercial potential have catalyzed interest in the development of effective intervention for OM. A range of small molecules are under development - some still in the preclinical stage, but others close to NDA submission. This review will focus on those drugs which have recently been assessed in a clinical trial and those which are still under clinical study as a prevention or treatment for radiation-associated OM.

EXPERT OPINION

In response to the unmet clinical need, both the biotechnology and pharmacological industries have been actively pursuing an agent to prevent/treat radiation-associated OM. This effort has been catalyzed by the identification of multiple drug targets which contribute to OM's pathogenesis. The lessons learned from the many trials which have previously stumbled have led to standardization of clinical trial design, endpoint efficacy definitions, rater assessment, and data interpretation over the past decade. Consequently, results of recently completed clinical trials provide optimism that effective treatment options should be available in the not-too-distant future.

Impact of radiation therapy on healthy tissues

Radiation therapy has a fundamental role in the management of cancers. However, despite a constant improvement in radiotherapy techniques, the issue of radiation-induced side effects remains clinically relevant. Mechanisms of acute toxicity and late fibrosis are therefore important topics for translational research to improve the quality of life of patients treated with ionizing radiations. Tissue changes observed after radiotherapy are consequences of complex pathophysiology, involving macrophage activation, cytokine cascade, fibrotic changes, vascularization disorders, hypoxia, tissue destruction and subsequent chronic wound healing. Moreover, numerous data show the impact of these changes in the irradiated stroma on the oncogenic process, with interplays between tumor radiation response and pathways involved in the fibrotic process. The mechanisms of radiation-induced normal tissue inflammation are reviewed, with a focus on the impact of the inflammatory process on the onset of treatment-related toxicities and the oncogenic process. Possible targets for pharmacomodulation are also discussed.

The protective effect of manganese superoxide dismutase from thermophilic bacterium HB27 on hydrochloric acid-induced chemical cystitis in rats

Purpose

To evaluate the effects of manganese superoxide dismutase (Mn-SOD) from thermophilic bacterium HB27 (name as Tt-SOD) on chemical cystitis.

Methods

Control and experimental rats were infused by intravesical saline or hydrochloric acid (HCl) on the first day of the experiments. Saline, sodium hyaluronate (SH) or Tt-SOD were infused intravesically once a day for three consequent days. On the fifth day, the rats were weighted and sacrificed following a pain threshold test. The bladder was harvested for histological and biochemical analyses.

Results

Tt-SOD could reduce the bladder index, infiltration of inflammatory cells in tissues, serum inflammatory factors and SOD levels, mRNA expression of inflammatory factors in tissues, and increase perineal mechanical pain threshold and serum MDA and ROS levels in HCl-induced chemical cystitis. Furthermore, Tt-SOD alleviated inflammation and oxidative stress by the negative regulation of the NF-κB p65 and p38 MAPK signaling pathway.

Conclusions

Intravesical instillation of Tt-SOD provides protective effects against HCl-induced cystitis.

Mechanism, Prevention, and Treatment of Radiation-Induced Salivary Gland Injury Related to Oxidative Stress

Radiation therapy is a common treatment for head and neck cancers. However, because of the presence of nerve structures (brain stem, spinal cord, and brachial plexus), salivary glands (SGs), mucous membranes, and swallowing muscles in the head and neck regions, radiotherapy inevitably causes damage to these normal tissues. Among them, SG injury is a serious adverse event, and its clinical manifestations include changes in taste, difficulty chewing and swallowing, oral infections, and dental caries. These clinical symptoms seriously reduce a patient’s quality of life. Therefore, it is important to clarify the mechanism of SG injury caused by radiotherapy. Although the mechanism of radiation-induced SG injury has not yet been determined, recent studies have shown that the mechanisms of calcium signaling, microvascular injury, cellular senescence, and apoptosis are closely related to oxidative stress. In this article, we review the mechanism by which radiotherapy causes oxidative stress and damages the SGs. In addition, we discuss effective methods to prevent and treat radiation-induced SG damage.

A hypothesis for the pathogenesis of radiation-induced oral mucositis: when biological challenges exceed physiologic protective mechanisms. Implications for pharmacological prevention and treatment

Oral mucositis (OM) remains a significant unmet need for patients being treated with standard concomitant chemoradiation (CRT) regimens for head and neck cancers (HNC). OM's pathogenesis is complex and includes both direct and indirect damage pathways. In this paper, the field is reviewed with emphasis on the initiating and sustaining role of oxidative stress on OM's pathobiology. A hypothesis is presented which suggests that based on OM's clinical and biological trajectory, mucosal damage is largely the consequence of cumulative CRT-induced biological changes overwhelming physiologic self-protective mechanisms. Furthermore, an individual's ability to mount and maintain a protective response is dependent on interacting pathways which are primarily determined by a multiplex consisting of genomics, epigenomics, and microbiomics. Effective biologic or pharmacologic OM interventions are likely to supplement or stimulate existing physiologic damage-control mechanisms.

Avasopasem manganese synergizes with hypofractionated radiation to ablate tumors through the generation of hydrogen peroxide

Avasopasem manganese (AVA or GC4419), a selective superoxide dismutase mimetic, is in a phase 3 clinical trial (NCT03689712) as a mitigator of radiation-induced mucositis in head and neck cancer based on its superoxide scavenging activity. We tested whether AVA synergized with radiation via the generation of hydrogen peroxide, the product of superoxide dismutation, to target tumor cells in preclinical xenograft models of non-small cell lung cancer (NSCLC), head and neck squamous cell carcinoma, and pancreatic ductal adenocarcinoma. Treatment synergy with AVA and high dose per fraction radiation occurred when mice were given AVA once before tumor irradiation and further increased when AVA was given before and for 4 days after radiation, supporting a role for oxidative metabolism. This synergy was abrogated by conditional overexpression of catalase in the tumors. In addition, in vitro NSCLC and mammary adenocarcinoma models showed that AVA increased intracellular hydrogen peroxide concentrations and buthionine sulfoximine- and auranofin-induced inhibition of glutathione- and thioredoxin-dependent hydrogen peroxide metabolism selectively enhanced AVA-induced killing of cancer cells compared to normal cells. Gene expression in irradiated tumors treated with AVA suggested that increased inflammatory, TNFα, and apoptosis signaling also contributed to treatment synergy. These results support the hypothesis that AVA, although reducing radiotherapy damage to normal tissues, acts synergistically only with high dose per fraction radiation regimens analogous to stereotactic ablative body radiotherapy against tumors by a hydrogen peroxide-dependent mechanism. This tumoricidal synergy is now being tested in a phase I-II clinical trial in humans (NCT03340974).

Superoxide Dismutase as an Intervention for Radiation Therapy-Associated Toxicities: Review and Profile of Avasopasem Manganese as a Treatment Option for Radiation-Induced Mucositis

Toxicities associated with radiation therapy are common, symptomatically devastating, and costly. The best chance to effectively mitigate radiation-associated normal tissue side effects are interventions aimed at disrupting the biological cascade, which is the basis for toxicity development, while simultaneously not reducing the beneficial impact of radiation on tumor. Oxidative stress is a key initiator of radiation-associated normal tissue injury as physiologic antioxidant mechanisms are overwhelmed by the accumulation of effects produced by fractionated treatment regimens. And fundamental to this is the generation of superoxide, which is normally removed by superoxide dismutases (SODs). Attempts to supplement the activity of endogenous SOD to prevent radiation-induced normal tissue injury have included the administration of bovine-derived SOD and increasing SOD production using gene transfer, neither of which has resulted in a clinically acceptable therapy. A third approach has been to develop synthetic small molecule dismutase mimetics. This approach has led to the creation and development of avasopasem manganese, a unique and specific dismutase mimetic that, in clinical trials, has shown promising potential to reduce the incidence, severity and duration of severe oral mucositis amongst patients being treated with concomitant chemoradiation for cancers of the head and neck. Further, avasopasem and related analogues have demonstrated mechanism-related antitumor synergy in combination with high dose per fraction radiotherapy, an observation that is also being tested in clinical trials. An ongoing Phase 3 trial seeks to confirm avasopasem manganese as an effective intervention for severe oral mucositis associated with chemoradiation in head and neck cancer patients.

Radiation-induced oral mucositis hamster model using a linear accelerator enhances clinical relevance of preclinical studies for treatment strategy investigation

Translational animal models for oral mucositis (OM) are necessary to simulate and assess the bioclinical effects and response in humans. These models should simulate high levels of radiation exposure that leads to oxidative stress and inflammatory-initiated tissue changes. Hamster models have been extensively studied to observe pathological effects of radiation exposure and help in the development of effective treatments. To successfully evaluate the potential for treatment regimens with consistency and relevance, a radiation-induced OM hamster model was developed using a clinical linear accelerator utilized by cancer patients daily. The dose exposure to the isolated, everted cheek pouch of a hamster, as well as the progression of injury, pro-inflammatory marker, histological, and elasticity analyses of the buccal pouch were conducted to verify replicability and reproducibility of the injury model. The findings from this model demonstrated its ability to consistently induce injury and resolution over 28 days using an acute dose of 60 Gy. This model was developed to enhance clinical relevance when evaluating potential efficacious treatments and can now be utilized in efficacy studies to better evaluate developed therapeutics in a preclinical model that is easy to translate to clinical studies..

Treatment for Oral Mucositis-Current Options and an Update of Small Molecules Under Development

OPINION STATEMENT

Despite its history as one of the most impactful toxicities associated with cytotoxic cancer therapy, oral mucositis (OM) remains an unmet clinical need which affects hundreds of thousands of patients. Descriptions of its complex pathogenesis have provided mechanistic targets which are being exploited to develop an effective therapeutic intervention. Favorable results of recently completed clinical trials in which agents focused on interrupting the early stages of the mucositis biological cascade were assessed provide reason for optimism, not only for oral mucositis but also for halo indications which share its pathobiogenesis.

Phototherapy With LED as an Effective Treatment for Chemotherapy-Induced Oral Mucositis in Hamsters

Introduction: Oral mucositis (OM) has been considered one of the most feared collateral effects of oncological treatments. Some therapies have been used, such as light-emitting diode (LED), with promising results, but with no sufficient evidence in the literature. Objective: Our study aimed to evaluate, by clinical and histological analysis, the effect of LED on the treatment of chemotherapy-induced OM (CIOM) in an animal model. Methods: Twenty male hamsters were equally distributed to two groups: control (C), which received anesthesia and CIOM induction; and LED (L), which received anesthesia, CIOM induction, and LED treatment (635 nm, 120 mW, 0.48 J). The clinical analysis was performed through two specific scales for OM analysis on days 5, 7 and 10 of the experiment. In addition, the injured area of all hamsters check pouch mucosa was removed and processed for histological analysis on the last experimental day. Results: After statistical analysis, group L showed less severity of OM when compared with the C group (P <0.05); beyond that, both healed completely on day 10. Conclusion: Our results suggested that the phototherapy with LED had a positive effect on accelerating repair, reducing the severity of CIOM.

Senolytics (DQ) Mitigates Radiation Ulcers by Removing Senescent Cells

Radiation ulcers are a prevalent toxic side effect in patients receiving radiation therapy. At present, there is still no effective treatment for the complication. Senescent cells accumulate after radiation exposure, which can induce cell and tissue dysfunction. Here we demonstrate increased expression of p16 (a senescence biomarker) in human radiation ulcers after radiotherapy and radiation-induced persistent cell senescence in animal ulcer models. Furthermore, senescent cells secreted the senescence-associated secretory phenotype (SASP) and induced cell senescence in adjacent cells, which was alleviated by JAK inhibition. In addition, the clearance of senescent cells following treatment with a senolytics cocktail, Dasatinib plus Quercetin (DQ), mitigated radiation ulcers. Finally, DQ induced tumor cell apoptosis and enhanced radiosensitivity in representative CAL-27 and MCF-7 cell lines. Our results demonstrate that cell senescence is involved in the development of radiation ulcers and that elimination of senescent cells might be a viable strategy for patients with this condition.

Antioxidant Therapy in Parkinson's Disease: Insights from Drosophila melanogaster

Reactive oxygen species (ROS) play an important role as endogenous mediators in several cellular signalling pathways. However, at high concentrations they can also exert deleterious effects by reacting with many macromolecules including DNA, proteins and lipids. The precise balance between ROS production and their removal via numerous enzymatic and nonenzymatic molecules is of fundamental importance for cell survival. Accordingly, many neurodegenerative disorders, including Parkinson’s disease (PD), are associated with excessive levels of ROS, which induce oxidative damage. With the aim of coping with the progression of PD, antioxidant compounds are currently receiving increasing attention as potential co-adjuvant molecules in the treatment of these diseases, and many studies have been performed to evaluate the purported protective effects of several antioxidant molecules. In the present review, we present and discuss the relevance of the use of Drosophila melanogaster as an animal model with which to evaluate the therapeutic potential of natural and synthetic antioxidants. The conservation of most of the PD-related genes between humans and D. melanogaster, along with the animal’s rapid life cycle and the versatility of genetic tools, makes fruit flies an ideal experimental system for rapid screening of antioxidant-based treatments.

Utilizing Superoxide Dismutase Mimetics to Enhance Radiation Therapy Response While Protecting Normal Tissues

Symptomatic normal tissue injury is a common side effect following definitive therapeutic radiation and chemotherapy treatment for a variety of malignancies. These cancer therapy related toxicities may occur acutely during treatment resulting in reduced or missed therapy agent administration or after the completion of therapy resulting in significant chronic morbidities that significantly diminish patient quality of life. Radiation and chemotherapy induce the formation of reactive oxygen species (ROS) both in normal tissues and tumor cells. One type of ROS common to both chemotherapy and radiation therapy is the formation of superoxide (O^2•-). Fortunately, due to metabolic differences between cancer and normal cell metabolism, as well as improved targeting techniques, ROS generation following radiation and chemotherapy is generally greater in cancer cells compared to normal tissues. However, the levels of ROS generated in normal tissues are capable of inducing significant toxicity. Thus, several groups are focusing on metabolism-based approaches to mitigate normal tissue effects occurring both during and following cancer therapy. This review will summarize the most current preclinical and clinical data available demonstrating the efficacy of small molecule, superoxide dismutase mimetics in minimizing radiation and chemotherapy-induced normal tissue injury, resulting in enhanced patient outcomes.

Effect of photobiomodulation on the severity of oral mucositis and molecular changes in head and neck cancer patients undergoing radiotherapy: a study protocol for a cost-effectiveness randomized clinical trial

Background

Oral mucositis (OM) is the most frequent and debilitating acute side effect associated with head and neck cancer (HNC) treatment. When present, severe OM negatively impacts the quality of life of patients undergoing HNC treatment. Photobiomodulation is a well-consolidated and effective therapy for the treatment and prevention of severe OM, and is associated with a cost reduction of the cancer treatment. Although an increase in the quality of life and a reduction in the severity of OM are well described, there is no study on cost-effectiveness for this approach considering the quality of life as a primary outcome. In addition, little is known about the photobiomodulation effects on salivary inflammatory mediators. Thus, this study aimed to assess the cost-effectiveness of the photobiomodulation therapy for the prevention and control of severe OM and its influence on the salivary inflammatory mediators.

Methods/design

This randomized, double-blind clinical trial will include 50 HNC patients undergoing radiotherapy or chemoradiotherapy. The participants will be randomized into two groups: intervention group (photobiomodulation) and control group (preventive oral care protocol). OM (clinical assessment), saliva (assessment of collected samples) and quality of life (Oral Health Impact Profile-14 and Patient-Reported Oral Mucositis Symptoms questionnaires) will be assessed at the 1st, 7th, 14th, 21st and 30th radiotherapy sessions. Oxidative stress and inflammatory cytokine levels will be measured in the saliva samples of all participants. The costs are identified, measured and evaluated considering the radiotherapy time interval. The incremental cost-effectiveness ratio will be estimated. The study will be conducted according to the Brazilian public health system perspective.

Discussion

Photobiomodulation is an effective therapy that reduces the cost associated with OM treatment. However, little is known about its cost-effectiveness, mainly when quality of life is the effectiveness measure. Additionally, this therapy is not supported by the Brazilian public health system. Therefore, this study widens the knowledge about the safety of and strengthens evidence for the use of photobiomodulation therapy, providing information for public policy-makers and also for dental care professionals. This study is strongly encouraged due to its clinical relevance and the possibility of incorporating new technology into public health systems.

Trial registration

Brazilian Registry of Clinical Trials—ReBEC, RBR-5h4y4n. Registered on 13 June 2017.

Electronic supplementary material

The online version of this article (10.1186/s13063-019-3196-8) contains supplementary material, which is available to authorized users.

Protective role of α2-macroglobulin against jaw osteoradionecrosis in a preclinical rat model

OBJECTIVE

We have previously demonstrated the effect of alpha-2-macroglobulin (α2M) in the remediation of radiation-induced cellular damage. Here, we investigated the protective effects of α2M in a preclinical rat model of jaw osteoradionecrosis (ORN).

METHODS

Eighteen rats were divided randomly into three groups: the control group, the radiation therapy (RT) alone group, and the radiated mandibles pretreated with α2M (α2M + RT) group. One month after radiation, all left molar teeth were extracted. After another 3 months, the animals were sacrificed and body weight, histopathology, microcomputed tomography and immunofluorescence were evaluated in all groups.

RESULTS

The RT group showed serious alopecia, bone exposure, inflammation, necrosis, fibrosis, and the absence of new bone formation within the socket. The α2M + RT group exhibited less alopecia than the RT group and slight inflammation and fibrosis in the bone marrow cavity. The cortical bone was similar to normal bone tissue. Interestingly, compared with RT group, serum superoxide dismutase levels in the α2M + RT group increased at the 1th day (P = 0.037), 14th day (P = 0.012), while reactive oxygen species levels clearly decreased at the 1th day (P< 0.001), 14th day (P = 0.007), and 28th day (P = 0.013).

CONCLUSIONS

A clinically translational model of jaw ORN was successfully established and the application of α2M prior to radiation protected the bone from being injured by the radiation, possibly related to oxidative stress.

Modulators of Redox Metabolism in Head and Neck Cancer

SIGNIFICANCE

Head and neck squamous cell cancer (HNSCC) is a complex disease characterized by high genetic and metabolic heterogeneity. Radiation therapy (RT) alone or combined with systemic chemotherapy is widely used for treatment of HNSCC as definitive treatment or as adjuvant treatment after surgery. Antibodies against epidermal growth factor receptor are used in definitive or palliative treatment. Recent Advances: Emerging targeted therapies against other proteins of interest as well as programmed cell death protein 1 and programmed death-ligand 1 immunotherapies are being explored in clinical trials.

CRITICAL ISSUES

The disease heterogeneity, invasiveness, and resistance to standard of care RT or chemoradiation therapy continue to constitute significant roadblocks for treatment and patients' quality of life (QOL) despite improvements in treatment modality and the emergence of new therapies over the past two decades.

FUTURE DIRECTIONS

As reviewed here, alterations in redox metabolism occur at all stages of HNSCC management, providing opportunities for improved prevention, early detection, response to therapies, and QOL. Bioinformatics and computational systems biology approaches are key to integrate redox effects with multiomics data from cells and clinical specimens and to identify redox modifiers or modifiable target proteins to achieve improved clinical outcomes. Antioxid. Redox Signal.

Radiation-Mediated Tumor Growth Inhibition Is Significantly Enhanced with Redox-Active Compounds That Cycle with Ascorbate

AIMS

We aim here to demonstrate that radiation (RT) enhances tumor sensitization by only those Mn complexes that are redox active and cycle with ascorbate (Asc), thereby producing H2O2 and utilizing it subsequently in protein S-glutathionylation in a glutathione peroxidase (GPx)-like manner. In turn, such compounds affect cellular redox environment, described by glutathione disulfide (GSSG)/glutathione (GSH) ratio, and tumor growth. To achieve our goal, we tested several Mn complexes of different chemical and physical properties in cellular and animal flank models of 4T1 breast cancer cell. Four other cancer cell lines were used to substantiate key findings.

RESULTS

Joint administration of cationic Mn porphyrin (MnP)-based redox active compounds, MnTE-2-PyP5+ or MnTnBuOE-2-PyP5+ with RT and Asc contributes to high H2O2 production in cancer cells and tumor, which along with high MnP accumulation in cancer cells and tumor induces the largest suppression of cell viability and tumor growth, while increasing GSSG/GSH ratio and levels of total S-glutathionylated proteins. Redox-inert MnP, MnTBAP3- and two other different types of redox-active Mn complexes (EUK-8 and M40403) were neither efficacious in the cellular nor in the animal model. Such outcome is in accordance with their inability to catalyze Asc oxidation and mimic GPx.

INNOVATION

We provided here the first evidence how structure-activity relationship between the catalytic potency and the redox properties of Mn complexes controls their ability to impact cellular redox environment and thus enhance the radiation and ascorbate-mediated tumor suppression.

CONCLUSIONS

The interplay between the accumulation of cationic MnPs and their potency as catalysts for oxidation of Asc, protein cysteines, and GSH controls the magnitude of their anticancer therapeutic effects.

Dimethyl Sulfoxide Prevents Radiation-Induced Oral Mucositis Through Facilitating DNA Double-Strand Break Repair in Epithelial Stem Cells

PURPOSE

Oral mucositis is one of the most prevalent side effects in patients undergoing radiation therapy for head and neck cancers. Current therapeutic agents such as palifermin recombinant human keratinocyte growth factor and amifostine do not efficiently or fully prevent mucositis. Dimethyl sulfoxide (DMSO), a free-radical scavenger, has shown therapeutic benefits in many preclinical and clinical studies. This study aimed to investigate the efficacy of DMSO in a clinically relevant mouse model of acute, radiation-induced oral mucositis.

METHODS AND MATERIALS

Oral mucositis was induced by a high single and fractioned irradiation of the head and neck area in C57BL/6J mice, and the effects of DMSO (by intraperitoneal injection) were assessed by macroscopic and histopathological examination. Epithelial stem and progenitor cells were analyzed by immunohistochemical staining of p63 and Ki-67, and DNA double-strand breaks (DSBs) were visualized by immunofluorescence detection of γ-H2AX. Tumor xenograft was obtained using CAL-27 cells.

RESULTS

Pretreatment with DMSO protected the oral mucosa from severe acute radiation injury, reduced the extent of radiation-induced weight loss, and had no significant effects on tumor weight in irradiated or nonirradiated xenograft mice. Furthermore, the efficacy of DMSO was superior to that of recombinant human keratinocyte growth factor and amifostine. DMSO treatment prevented the loss of proliferative lingual epithelial stem and progenitor cells upon irradiation. More interestingly, the average levels of γ-H2AX foci were significantly decreased in p63-positive epithelial stem cells at 6 hours, but not at 2 hours, after irradiation, indicating that DMSO facilitated DNA DSB repair rather than suppressing the indirect action of irradiation.

CONCLUSIONS

DMSO prevents the loss of proliferative lingual epithelial stem and progenitor cells upon irradiation by facilitating DNA DSB repair, thereby protecting against radiation-induced mucositis without tumor protection. Given its high efficacy and low toxicity, DMSO could be a potential treatment option to prevent radiation-induced oral mucositis.

Superoxide Radical Dismutation as New Therapeutic Strategy in Parkinson's Disease

Aging is the biggest risk factor for developing many neurodegenerative disorders, including idiopathic Parkinson's disease (PD). PD is still an incurable disorder and the available medications are mainly directed to the treatment of symptoms in order to improve the quality of life. Oxidative injury has been identified as one of the principal factors involved in the progression of PD and several indications are now reported in the literature highlighting the prominent role of the superoxide radical in inducing neuronal toxicity. It follows that superoxide anions represent potential cellular targets for new drugs offering a novel therapeutic approach to cope with the progression of the disease. In this review we first present a comprehensive overview of the most common cellular reactive oxygen and nitrogen species, describing their cellular sources, their potential physiological roles in cell signalling pathways and the mechanisms through which they could contribute to the oxidative damage. We then analyse the potential therapeutic use of SOD-mimetic molecules, which can selectively remove superoxide radicals in a catalytic way, focusing on the classes of molecules that have therapeutically exploitable properties.

Phase 1b/2a Trial of the Superoxide Dismutase Mimetic GC4419 to Reduce Chemoradiotherapy-Induced Oral Mucositis in Patients With Oral Cavity or Oropharyngeal Carcinoma

PURPOSE

To assess the safety of the superoxide dismutase mimetic GC4419 in combination with radiation and concurrent cisplatin for patients with oral cavity or oropharyngeal cancer (OCC) and to assess the potential of GC4419 to reduce severe oral mucositis (OM).

PATIENTS AND METHODS

Patients with locally advanced OCC treated with definitive or postoperative intensity modulated radiation therapy (IMRT) plus cisplatin received GC4419 by 60-minute intravenous infusion, ending <60 minutes before IMRT, Monday through Friday for 3 to 7 weeks, in a dose and duration escalation study. Oral mucositis was assessed twice weekly during and weekly after IMRT.

RESULTS

A total of 46 patients received GC4419 in 11 separate dosing and duration cohorts: dose escalation occurred in 5 cohorts receiving 15 to 112 mg/d over 3 weeks (n=20), duration escalation in 3 cohorts receiving 112 mg/d over 4 to 6 weeks (n=12), and then 3 additional cohorts receiving 30 or 90 mg/d over 6 to 7 weeks (n=14). A maximum tolerated dose was not reached. One dose-limiting toxicity (grade 3 gastroenteritis and vomiting with hyponatremia) occurred in each of 2 separate cohorts at 112 mg. Nausea/vomiting and facial paresthesia during infusion seemed to be GC4419 dose-related. Severe OM occurred through 60 Gy in 4 of 14 patients (29%) dosed for 6 to 7 weeks, with median duration of only 2.5 days.

CONCLUSIONS

The safety of GC4419 concurrently with chemoradiation for OCC was acceptable. Toxicities included nausea/vomiting and paresthesia. Doses of 30 and 90 mg/d administered for 7 weeks were selected for further study. In an exploratory analysis, severe OM seemed less frequent and briefer than expected.

Hangeshashinto (TJ-14) prevents radiation-induced mucositis by suppressing cyclooxygenase-2 expression and chemotaxis of inflammatory cells

PURPOSE

Radiation-induced oral mucositis is the most common side effect of radiotherapy in head and neck cancer; however, effective modalities for its prevention have not been established. In this study, we evaluated the effectiveness of Hangeshashinto (TJ-14), a Japanese herbal medicine, for preventing radiation-induced mucositis and elucidated its effect on inflammatory responses, including inflammatory cell chemotaxis and cyclooxygenase-2 (COX2) expression, in an animal model.

METHODS

Syrian hamsters, 8-9 weeks old, were enrolled in this study. Animals were irradiated with a single 40 Gy dose to the buccal mucosa. Hamsters freely received a treatment diet mixed with 2% TJ-14 or a normal diet daily. The therapeutic effect was determined based on the visual mucositis score, body weight, and histological examination of infiltrated neutrophils and COX2 expression.

RESULTS

TJ-14 significantly reduced the severity of mucositis. The percentage with severe mucositis (score ≥3) was 100% in the untreated group and 16.7% in the TJ-14 group (P < 0.05). There was no difference in body weight change between the groups; however, weight gain in the untreated group tended to be suppressed compared to that in the TJ-14 group during the peak period of mucositis. In addition, TJ-14 inhibited the infiltration of neutrophils and COX2 expression in irradiated mucosa (P < 0.05).

CONCLUSIONS

TJ-14 reduced the severity of mucositis in an animal model by suppressing the inflammatory response. Because TJ-14 is inexpensive and its safety is established, it is a promising candidate for the standard treatment of radiation-induced mucositis in cancer patients.

Melatonin protects rats from radiotherapy-induced small intestine toxicity

Radiotherapy-induced gut toxicity is among the most prevalent dose-limiting toxicities following radiotherapy. Prevention of radiation enteropathy requires protection of the small intestine. However, despite the prevalence and burden of this pathology, there are currently no effective treatments for radiotherapy-induced gut toxicity, and this pathology remains unclear. The present study aimed to investigate the changes induced in the rat small intestine after external irradiation of the tongue, and to explore the potential radio-protective effects of melatonin gel. Male Wistar rats were subjected to irradiation of their tongues with an X-Ray YXLON Y.Tu 320-D03 irradiator, receiving a dose of 7.5 Gy/day for 5 days. For 21 days post-irradiation, rats were treated with 45 mg/day melatonin gel or vehicle, by local application into their mouths. Our results showed that mitochondrial oxidative stress, bioenergetic impairment, and subsequent NLRP3 inflammasome activation were involved in the development of radiotherapy-induced gut toxicity. Oral treatment with melatonin gel had a protective effect in the small intestine, which was associated with mitochondrial protection and, consequently, with a reduced inflammatory response, blunting the NF-κB/NLRP3 inflammasome signaling activation. Thus, rats treated with melatonin gel showed reduced intestinal apoptosis, relieving mucosal dysfunction and facilitating intestinal mucosa recovery. Our findings suggest that oral treatment with melatonin gel may be a potential preventive therapy for radiotherapy-induced gut toxicity in cancer patients.

On the pathogenesis of mTOR inhibitor-associated stomatitis (mIAS)-studies using an organotypic model of the oral mucosa

OBJECTIVE

mTOR inhibitor treatment of solid cancers is associated with mTOR inhibitor-associated stomatitis (mIAS) a common, significant, dose-limiting toxicity, with aphthous-like lesions. Our objective was to assess the utility of a new organotypic model in defining mIAS' pathogenesis.

MATERIALS AND METHODS

The effect of everolimus on organotypic human oral mucosa was studied. Sterile specimens were assessed 24 and 48 h after exposure to varying concentrations of everolimus. Morphologic changes and measures of apoptosis, proliferation, and levels of six Th1 and Th2 cytokines were studied.

RESULTS

Following a 24-h incubation, concentrations of 500 ng ml^-1 of everolimus resulted in histological changes consistent with epithelial injury, disorganization and pre- or early apoptosis, increased TUNEL-positive staining (P < 0.05) and reduced PCNA-positive staining cells (P < 0.001) and increased levels of IL-6 (P < 0.0001), IL-8 (P < 0.01), and IFN-γ (P < 0.09).

CONCLUSIONS

Everolimus elicited epithelial damage manifest by morphologic changes, increased apoptosis, and decreased proliferation with concurrent release of keratinocyte-derived pro-inflammatory cytokines in the absence of bacteria. The extent of the effect was concentration and time dependent. These results suggest that mIAS is likely initiated by direct epithelial injury, independent of the microbiome. Keratinocyte cytokine release could likely play a role in accelerating an inflammatory infiltrate.

Pharmacotherapy for the management of cancer regimen-related oral mucositis

INTRODUCTION

Oral mucositis is a frequent and devastating toxicity secondary to cancer treatment, which may affect 20-40% of patients receiving conventional chemotherapy and 60-85% of patients undergoing hematopoietic stem cell transplantation. The pathobiology of mucositis includes a complex cascade of biologic events in which pro-inflammatory cytokines, ROS, second messengers, and the oral microbiome contribute to tissue damage of the oral mucosa. Management strategies to oral mucositis secondary to chemotherapy include preventative measures and therapeutic approaches.

AREA COVERED

A literature search of published animal and clinical studies was perform to review the epidemiology, pathophysiology and treatment options for cancer regimen-induced mucositis. We also discuss new data coming from recent pertinent clinical trials.

EXPERT OPINION

Mucositis is one of the most common debilitating toxicities secondary to cancer treatment and can adversely affect patients' quality of life. Epidemiological data for mucositis are often under-reported. Research efforts have shown that genetics plays a major role in the development of this toxicity. Although few therapeutic agents are available, several promising drugs are under investigations.

Adipose mesenchymal stromal cells minimize and repair radiation-induced oral mucositis

BACKGROUND AIMS

Mesenchymal stromal cells (MSCs) have been used to minimize and repair radiation-induced normal tissue injury in the intestine, salivary gland, liver, skin, lungs and cardiac muscle. This study investigated the ability of adipose tissue-derived MSCs (aMSCs) to minimize and/or repair single dose radiation-induced oral mucositis (RIOM).

METHODS

Syngenic phenotypically and functionally characterized BALB/c mouse aMSCs were implanted intraperitoneally in a RIOM mouse model with different dosing protocols. Response was quantified macroscopically, microscopically and by using different histological and clinically relevant parameters.

RESULTS

Irradiation at 18 Gy generated a self-resolved single-dose RIOM BALB/c mouse model with 5.6 ± 0.3 days mean duration (95% confidence interval (CI) 4.233-7.1 days) and 100% survival rate. Intraperitoneal implantation of 5 doses of 2.5 million freshly cultured syngenic aMSCs significantly and reproducibly reduced RIOM ulcer duration to 1.6 ± 0.3 days (95% CI 0.0233-3.1 days, a 72% reduction in RIOM ulcer duration), ulcer size and ulcer floor epithelial height. The therapeutic benefits were significantly dependent on dose size and frequency, number of doses, and therapy onset time. aMSCs therapy significantly minimized the RIOM-related weight loss, accelerated the weight gain and improved irradiated animals' hydration and nutritional status. aMSCs therapy did not potentiate head and neck cancer in vitro.

CONCLUSIONS

Syngenic freshly cultured aMSCs significantly minimized and repaired radiation-induced oral mucositis with a 72% reduction in ulcer duration. aMSCs dose size and frequency, number of doses and therapy onset time are the main keys for optimized therapeutic outcome. aMSCs therapy did not stimulate Head and Neck cancer cell growth in-vitro.

New frontiers in mucositis

Mucositis is among the most debilitating side effects of radiotherapy, chemotherapy, and targeted anticancer therapy. Research continues to escalate regarding key issues such as etiopathology, incidence and severity across different mucosae, relationships between mucosal and nonmucosal toxicities, and risk factors. This approach is being translated into enhanced management strategies. Recent technology advances provide an important foundation for this continuum. For example, evolution of applied genomics is fostering development of new algorithms to rapidly screen genomewide single-nucleotide polymorphisms (SNPs) for patient-associated risk prediction. This modeling will permit individual tailoring of the most effective, least toxic treatment in the future. The evolution of novel cancer therapeutics is changing the mucositis toxicity profile. These agents can be associated with unique mechanisms of mucosal damage. Additional research is needed to optimally manage toxicity caused by agents such as mammalian target of rapamycin (mTOR) inhibitors and tyrosine kinase inhibitors, without reducing antitumor effect. There has similarly been heightened attention across the health professions regarding clinical practice guidelines for mucositis management in the years following the first published guidelines in 2004. New opportunities exist to more effectively interface this collective guideline portfolio by capitalizing upon novel technologies such as an Internet-based Wiki platform. Substantive progress thus continues across many domains associated with mucosal injury in oncology patients. In addition to enhancing oncology patient care, these advances are being integrated into high-impact educational and scientific venues including the National Cancer Institute Physician Data Query (PDQ) portfolio as well as a new Gordon Research Conference on mucosal health and disease scheduled for June 2013.

Mechanism-based management for mucositis: option for treating side effects without compromising the efficacy of cancer therapy

Mucositis is a major side effect induced by chemotherapy and radiotherapy. Although mucositis is a leading cause of morbidity and mortality in cancer patients, management is largely limited to controlling symptoms, and few therapeutic agents are available for treatment. Since mucositis could be inhibited by the modulation of radiotherapy- or chemotherapy-induced pathways independently of cancer treatment, there is an opportunity for the development of more targeted therapies and interventions. This article examined potential therapeutic agents that have been investigated for the prevention and/or inhibition of mucositis induced by conventional chemotherapy and radiotherapy. They can be classified according to their mechanisms of action: scavenging reactive oxygen species, inhibition of specific cytokine production or inflammation, and inhibition of apoptosis. These early events may be good target pathways for preventing the pathogenesis of mucositis. Considering that both cancer therapy and therapeutic agents for mucositis act on both normal and cancer cells, agents that inhibit mucositis should act through mechanisms that selectively protect normal cells without compromising cancer treatment. Therefore, mechanism-based guidance for the treatment of mucositis is critical to prevent risky treatments for cancer patients and to relieve detrimental side effects effectively from cancer therapy.

Superoxide Dismutase (SOD)-mimetic M40403 Is Protective in Cell and Fly Models of Paraquat Toxicity: IMPLICATIONS FOR PARKINSON DISEASE

Parkinson disease is a debilitating and incurable neurodegenerative disorder affecting ∼1–2% of people over 65 years of age. Oxidative damage is considered to play a central role in the progression of Parkinson disease and strong evidence links chronic exposure to the pesticide paraquat with the incidence of the disease, most probably through the generation of oxidative damage. In this work, we demonstrated in human SH-SY5Y neuroblastoma cells the beneficial role of superoxide dismutase (SOD) enzymes against paraquat-induced toxicity, as well as the therapeutic potential of the SOD-mimetic compound M40403. Having verified the beneficial effects of superoxide dismutation in cells, we then evaluated the effects using Drosophila melanogaster as an in vivo model. Besides protecting against the oxidative damage induced by paraquat treatment, our data demonstrated that in Drosophila M40403 was able to compensate for the loss of endogenous SOD enzymes, acting both at a cytosolic and mitochondrial level. Because previous clinical trials have indicated that the M40403 molecule is well tolerated in humans, this study may have important implication for the treatment of Parkinson disease.

Mucositis: pathobiology and management

PURPOSE OF REVIEW

Oral mucositis remains a frequent debilitating toxicity associated with drug and radiation regimens used to treat cancer. This review highlights the recent understanding of the biological basis, risk factors for, and management for oral mucositis.

RECENT FINDINGS

Prevalence and incidence data for mucositis are inconsistent and often underreported. The pathogenesis of mucositis encompasses a sequence of biological events possibly influenced by the oral microbiome and environment. Despite its frequency and severity, there is currently no effective treatment available for the majority of patients at risk. However, with the better understanding of the pathogenesis of mucositis a number of new drugs and biological agents are under investigation. Genome-wide risk prediction tools will allow the identification of patients at risk of developing mucositis.

SUMMARY

Oral mucositis is a common complication of cancer treatment that may negatively impact the patient's cancer treatment outcome. Despite its frequency and consequences, the lack of effective interventions has frustrated patients and caregivers. Fortunately, a broad range of mechanistically targeted compounds are being developed.

Antioxidants in Translational Medicine

SIGNIFICANCE

It is generally accepted that reactive oxygen species (ROS) scavenging molecules or antioxidants exert health-promoting effects and thus their consumption as food additives and nutraceuticals has been greatly encouraged. Antioxidants may be beneficial in situations of subclinical deficiency and increased demand or acutely upon high-dose infusion. However, to date, there is little clinical evidence for the long-term benefit of most antioxidants. Alarmingly, recent evidence points even to health risks, in particular for supplements of lipophilic antioxidants.

RECENT ADVANCES

The biological impact of ROS depends not only on their quantities but also on their chemical nature, (sub)cellular and tissue location, and the rates of their formation and degradation. Moreover, ROS serve important physiological functions; thus, inappropriate removal of ROS may cause paradoxical reductive stress and thereby induce or promote disease.

CRITICAL ISSUES

Any recommendation on antioxidants must be based on solid clinical evidence and patient-relevant outcomes rather than surrogate parameters.

FUTURE DIRECTIONS

Such evidence-based use may include site-directed application, time-limited high dosing, (functional) pharmacological repair of oxidized biomolecules, and triggers of endogenous antioxidant response systems. Ideally, these approaches need guidance by patient stratification through predictive biomarkers and possibly imaging modalities.

Treatment-related gastrointestinal toxicities and advanced colorectal or pancreatic cancer: A critical update

Gastrointestinal toxicities (GIT), including oral mucositis, nausea and vomiting, and diarrhea, are common side effects of chemotherapy and targeted agents in patients with advanced colorectal cancer and pancreatic cancer. Being often underreported, it is still difficult to precisely establish their burden in terms of both patient’s quality of life and cancer care costs. Moreover, with the use of more intensive upfront combination regimens, the frequency of these toxicities is rapidly growing with a potential negative effect also on patient’s outcome, as a result of dose reductions, delays or even discontinuation of active treatments. Thus, identifying patients at higher risk of developing GIT as well as an optimal management are paramount in order to improve patient’s compliance and outcome. After the description of the main treatment-induced GIT, we discuss the current knowledge on the pathophysiology of these side effects and comment the scales commonly used to assess and grade them. We then provide a critical update on GIT incidence based on the results of key randomized trials conducted in patients with metastatic colorectal cancer and advanced pancreatic cancer.

Metal complexes of pyridine-fused macrocyclic polyamines targeting the chemokine receptor CXCR4

The chemokine receptor CXCR4 acts as a key cell surface receptor in HIV infections, multiple forms of cancer, and various other pathologies, such as rheumatoid arthritis and asthma. Macrocyclic polyamines and their metal complexes are known to exert anti-HIV activity, many acting as HIV entry inhibitors by specifically binding to CXCR4. Three series of pyridopentaazacylopentadecanes, in which the pyridine ring is fused to zero, one, or two saturated six-membered rings, were synthesized by manganese(ii)-templated Schiff-base cyclization of triethylenetetramine with various dicarbonyl compounds. By evaluating these macrocyclic polyamines and their complexes with Mn(2+), Cu(2+), Fe(3+), and Zn(2+), we have discovered novel CXCR4-binding compounds. The MnCl2 complex of a new pentaazacyclopentadecane with one fused carbocyclic ring (11) was found to have the greatest potency as an antagonist of the chemokine receptor CXCR4 (IC50: 0.014 μM), as evidenced by inhibiting binding of CXCL12 to PBMCs (peripheral blood mononuclear cells). Consequently, this compound inhibits replication of the CXCR4-using (X4) HIV-1 strain NL4-3 in the TZM-bl cell line with an IC50 value of 0.52 μM and low cytotoxicity (CC50: >100 μM). In addition, 18 other compounds were evaluated for their interaction with CXCR4 via their ability to interfere with ligand chemokine binding and HIV entry and infection. Of these, the metal complexes of the two more hydrophobic series with one or two fused carbocyclic rings exhibited the greatest potency. The Zn(2+) complex 21 was among the most potent, showing that redox activity of the metal center is not associated with CXCR4 antagonist activity.

Radioprotective agents for radiation therapy: future trends

Only two radioprotective compounds, amifostine and palifermin, currently have the US FDA approval for use in radiation therapy. However, several agents have been reported that show therapeutic promise. Many of these agents are free radical scavengers/antioxidants. Superoxide dismutase and superoxide dismutase mimetics, nitroxides and dietary antioxidants are all being investigated. Recently, alternative strategies of drug development have been evolving, which focus on targeting the series of cellular insult recognition/repair responses initiated following radiation. These agents, which include cytokines/growth factors, angiotensin-converting enzyme inhibitors and apoptotic modulators, show promise of having significant impact on the mitigation of radiation injury. Herein, we review current literature on the development of radioprotectors with emphasis on compounds with proven or potential usefulness in radiation therapy.

Nano structure zinc (II) Schiff base complexes of a N3-tridentate ligand as new biological active agents: spectral, thermal behaviors and crystal structure of zinc azide complex

In this work, synthesis of some new five coordinated zinc halide/pseudo-halide complexes of a N3-tridentate ligand is presented. All complexes were subjected to spectroscopic and physical methods such as FT-IR, UV-visible, (1)H and (13)C NMR spectra, thermal analyses and conductivity measurements for identification. Based on spectral data, the general formula of ZnLX2 (X=Cl(-), Br(-), I(-), SCN(-) and N3(-)) was proposed for the zinc complexes. Zinc complexes have been also prepared in nano-structure sizes under ultrasonic irradiation. X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were applied for confirmation of nano-structure character for the complexes. Among the complexes, zinc azide complex structure was analyzed by X-ray crystallography. This complex crystallizes as a triplet in trigonal system with space group of P31. The coordination sphere around the zinc center is well shown as a distorted trigonal bipyramidal with three nitrogen atoms from Schiff base ligand and two terminal azide nitrogen atoms attached to zinc ion. Various intermolecular interactions such as NH⋯N, CH⋯N and CH⋯π hydrogen bonding interactions stabilize crystalline lattice so that they causes a three dimensional supramolecular structure for the complex. In vitro screening of the compounds for their antimicrobial activities showed that ZnLI2, ZnL(N3)2, ZnLCl2 and ZnL(NCS)2 were found as the most effective compound against bacteria of Bacillus subtilis, Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli respectively. Also ZnLI2 and ZnLCl2 complexes were found more effective against two selected fungi than others. Finally, thermal behaviors of the zinc complexes showed that they are decomposed via 2-4 thermal steps from room temperature up to 1000°C.

Clinical, biochemical and histological study of the effect of antimicrobial photodynamic therapy on oral mucositis induced by 5-fluorouracil in hamsters

Oral mucositis (OM) is a debilitating side effect of chemotherapy, which can be relieved by phototherapy. Antimicrobial photodynamic therapy (aPDT) may be used for the treatment of OM, when infection is present. However, there are no studies showing that aPDT affects tissue repair process when used in the treatment of lesions caused by OM. This work aims to evaluate the effect of aPDT in healing OM induced by 5-Fluorouracil (5-FU). Two hundred forty-five hamsters were divided into two groups, control (C) and experimental, which were subdivided into 4 subgroups (Ch, ChP, ChL, aPDT). C group received only the vehicle of chemotherapy and anesthesia, whereas all animals of the experimental groups received anesthesia and chemotherapy agent 5-FU to induce OM. Ch group received no OM treatment; ChP group received an application of methylene blue (MB) 0.01%; ChL received irradiation with low-power-laser (LPL-660 nm/120 J /cm(2)/40 mW/4.4 J per point); and aPDT received MB and LPL irradiation. OM Clinical severity were daily assessed by a blinded examiner. The animals were sacrificed after 5, 7 and 10 days of experiment and their oral mucosa were removed for biochemical (enzymatic activity of SOD and catalase) and histological analyzes (light microscopy). After statistical analysis was performed, results showed that aPDT reduced the severity of OM on the tenth day of the experiment, when compared to the initial OM score (p < 0.05), as well as increased keratinization with organized collagen deposition in the lamina propria. In conclusion, aPDT can be safely used in animals with infected OM because it does not affect lesion-repairing processes.

Histopathologic grading of oral mucositis

OBJECTIVE

Oral mucositis is a common adverse effect of cytotoxic chemotherapy and radiation, and it causes debilitating morbidity that may necessitate interruptions in cancer treatment. Animal models of oral mucositis are invaluable tools for testing novel therapeutics, but grading of lesions based on subjective assessments makes conformism between studies difficult. A standardized scoring system that can objectively and reproducibly grade the severity of oral mucositis is critical in comparing and validating efficacies of developing therapeutics.

MATERIALS AND METHODS

The head region of male Balb/C animals was exposed to collimated radiation delivered as fractions of 8 Gy on three consecutive days, or as a single large dose of 22.5 Gy. The development of oral toxicity was assessed by histologic analysis of the tongue at various days postradiation.

RESULTS

After fractionated radiation, early epithelial atypia of basal cell layer disorganization and nuclear aberrations was evident by day 6. The disease displayed moderate changes of epithelial atrophy and dyskeratosis by day 7.5 with subsequent epithelial breakdown and ulceration by day 9. In contrast, exposure to a single large-dose radiation resulted in bulla formation by day 9 in most animals.

CONCLUSIONS

An oral mucositis grading system based on histopathologic scoring of tissues is proposed.

SOD therapeutics: latest insights into their structure-activity relationships and impact on the cellular redox-based signaling pathways

SIGNIFICANCE

Superoxide dismutase (SOD) enzymes are indispensable and ubiquitous antioxidant defenses maintaining the steady-state levels of O2·(-); no wonder, thus, that their mimics are remarkably efficacious in essentially any animal model of oxidative stress injuries thus far explored.

RECENT ADVANCES

Structure-activity relationship (half-wave reduction potential [E1/2] versus log kcat), originally reported for Mn porphyrins (MnPs), is valid for any other class of SOD mimics, as it is dominated by the superoxide reduction and oxidation potential. The biocompatible E1/2 of ∼+300 mV versus normal hydrogen electrode (NHE) allows powerful SOD mimics as mild oxidants and antioxidants (alike O2·(-)) to readily traffic electrons among reactive species and signaling proteins, serving as fine mediators of redox-based signaling pathways. Based on similar thermodynamics, both SOD enzymes and their mimics undergo similar reactions, however, due to vastly different sterics, with different rate constants.

CRITICAL ISSUES

Although log kcat(O2·(-)) is a good measure of therapeutic potential of SOD mimics, discussions of their in vivo mechanisms of actions remain mostly of speculative character. Most recently, the therapeutic and mechanistic relevance of oxidation of ascorbate and glutathionylation and oxidation of protein thiols by MnP-based SOD mimics and subsequent inactivation of nuclear factor κB has been substantiated in rescuing normal and killing cancer cells. Interaction of MnPs with thiols seems to be, at least in part, involved in up-regulation of endogenous antioxidative defenses, leading to the healing of diseased cells.

FUTURE DIRECTIONS

Mechanistic explorations of single and combined therapeutic strategies, along with studies of bioavailability and translational aspects, will comprise future work in optimizing redox-active drugs.

Local and systemic pathogenesis and consequences of regimen-induced inflammatory responses in patients with head and neck cancer receiving chemoradiation

Treatment-related toxicities are common among patients with head and neck cancer, leading to poor clinical outcomes, reduced quality of life, and increased use of healthcare resources. Over the last decade, much has been learned about the pathogenesis of cancer regimen-related toxicities. Historically, toxicities were separated into those associated with tissue injury and those with behavioural or systemic changes. However, it is now clear that tissue-specific damage such as mucositis, dermatitis, or fibrosis is no longer the sole consequence of direct clonogenic cell death, and a relationship between toxicities that results in their presentation as symptom clusters has been documented and attributed to a common underlying pathobiology. In addition, the finding that patients commonly develop toxicities representing tissue injury outside radiation fields and side effects such as fatigue or cognitive dysfunction suggests the generation of systemic as well as local mediators. As a consequence, it might be appropriate to consider toxicity syndromes, rather than the traditional approach, in which each side effect was considered as an autonomous entity. In this paper, we propose a biologically based explanation which forms the basis for the diverse constellation of toxicities seen in response to current regimens used to treat cancers of the head and neck.

Protective effects of Korean red ginseng on radiation-induced oral mucositis in a preclinical rat model

Numerous studies' attempts to improve radiation-induced oral mucositis have not produced a qualified treatment yet. Our aim was to investigate the effectiveness of Korean red ginseng (KRG) on radiation-induced damage in an in vivo rat model. After 20 Gy of irradiation, rats were divided randomly into the following 4 groups: control, KRG only, radiotherapy (RT) only, and RT + KRG group. The rats were monitored in terms of survival rate, activity, mucositis grade, oral intake, and body weight. The tongue, buccal mucosa, and submandibular gland (SMG) were harvested, and the weight of the SMG was analyzed. The samples then underwent hematoxylin and eosin, TUNEL, and immunohistochemical staining. Radiation-induced severe oral mucositis and SMG injury led to poor oral intake and delayed healing, resulting in the death of some rats. We found that survival rate, oral intake, and body weight increased. Moreover, rats treated with KRG showed less severe mucositis and decreased histologic changes of the oral mucosa and SMG. Furthermore, we showed that the protective effects of KRG were caused by inhibition of the apoptotic signal transduction pathway linked to caspase-3. In conclusion, KRG protects the oral mucosa and SMG from radiation-induced damage by inhibiting caspase-mediated apoptosis in rats.

Alteration of the redox state with reactive oxygen species for 5-fluorouracil-induced oral mucositis in hamsters

Oral mucositis is often induced in patients receiving cancer chemotherapy treatment. It has been reported that oral mucositis can reduce quality of life, as well as increasing the incidence of mortality. The participation of reactive oxygen species (ROS) in the pathogenesis of oral mucositis is well known, but no report has actually demonstrated the presence of ROS. Thus, the purpose of this study was thus to demonstrate the involvement of ROS and the alteration of the redox state in oral mucositis using an in vivo L-band electron spin resonance (ESR) technique. An oral mucositis animal model induced by treatment of 5-fluorouracil with 10% acetic acid in hamster cheek pouch was used. Lipid peroxidation was measured as the level of malondialdehyde determined by the thiobarbituric acid reaction. The rate constants of the signal decay of nitroxyl compounds using in vivo L-band ESR were calculated from the signal decay curves. Firstly, we established the oral mucositis animal model induced by treatment of 5-fluorouracil with acetic acid in hamster cheek pouch. An increased level of lipid peroxidation in oral mucositis was found by measuring malondialdehyde using isolated hamster cheek pouch ulcer. In addition, as a result of in vivo L-band ESR measurements using our model animals, the decay rate constants of carbamoyl-PROXYL, which is a reagent for detecting the redox balance in tissue, were decreased. These results suggest that a redox imbalance might occur by excessive generation of ROS at an early stage of oral mucositis and the consumption of large quantities of antioxidants including glutathione in the locality of oral mucositis. These findings support the presence of ROS involved in the pathogenesis of oral mucositis with anti-cancer therapy, and is useful for the development of novel therapies drugs for oral mucositis.