The International Gynecologic Cancer Society consensus statement on palliative care.

At the International Gynecologic Cancer Society (IGCS) Global Meeting in 2023 held in Seoul, South Korea, we held a Presidential Plenary Session focusing on palliative care (https://www.youtube.com/watch?v=TBDIoQ50xgI). We hereby reaffirm the significance of this session, express the Palliative Care Declaration made by the IGCS, and describe our action plan for the future.

Exploratory Research on Determinants of Place of Death in a Large-scale Cohort Study: The JPHC Study.

BACKGROUND: The place of death and related factor, such as diseases, symptoms, family burden, and cost, has been examined, but social background and lifestyle were not considered in most studies. Here, we assessed factors that are associated with the place of death using the largest cohort study in Japan. METHODS: A total of 17,781 deaths from the cohort study were assessed. The study database was created from the Japan Public Health Center-based Prospective Study (JPHC Study), in which demographic data were collected from Japanese Vital Statistics. Adjusted odds ratios for home death were calculated using logistic regression. RESULTS: Multivariate analysis adjusted for various factors showed that unmarried status (odds ratio [OR] 2.4; 95% confidence interval [CI], 2.0-2.9), unemployed male (OR 1.3; 95% CI, 1.1-1.5), and high drinking level in male (OR 1.3; 95% CI, 1.1-1.6) were associated with home death. Regarding the cause of death, cardiovascular disease (OR 3.3; 95% CI, 2.9-3.8), cerebrovascular disease (OR 1.9; 95% CI, 1.6-2.2), and external factors (OR 4.1; 95% CI, 3.5-4.8) were significantly associated with home death, compared with cancer. The risk of death at home was significantly higher among unmarried subjects stratified by cause of death (cardiovascular disease: OR 3.2; 95% CI, 2.2-4.7; cerebrovascular disease: OR :5.1; 95% CI, 2.9-9.1; respiratory disease: OR 3.4; 95% CI, 1.6-7.6; and external factors: OR 2.3; 95% CI, 1.4-3.7), but for cancer, the risk of death at home tended to be higher among married participants. CONCLUSION: This study found that various factors are associated with home death using the largest cohort study in Japan. There is a high possibility of home deaths in people with fewer social connections and in those with diseases leading to sudden death.

Elevated free thyroxine and free triiodothyronine probably caused by high-dose biotin intake in a patient with Graves' disease: a case report.

Biotin is a water-soluble vitamin that acts as a cofactor for carboxylase, and is often used as a component in several immunoassays. We present a case of a 46-year-old male with Graves' disease (GD) who revealed elevated free thyroxine (FT4) and free triiodothyronine (FT3) levels after high-dose biotin intake. Levels of these hormones had been within the reference range when he was on thiamazole 5 mg/day for 7 years; however, the levels increased from 1.04 to 2.20 ng/dL and from 3.05 to 9.84 pg/mL for FT4 and FT3, respectively, after he started taking biotin 72 mg/day. Despite these high levels, his symptoms and the other laboratory results, including the thyroid-stimulating hormone level, did not suggest GD relapse. His thyroid hormone data was decreased and returned within the reference range immediately after the laboratory assays for FT3 and FT4 had been coincidentally changed from those containing streptavidin-biotin complexes to biotin-free ones. Biotin interference, which is caused by high-dose biotin intake and immunoassays using some form of streptavidin-biotin complex, is sometimes clinically problematic, giving high or low results. To our knowledge, this is the first case report of a patient with GD on high-dose biotin receiving high thyroid hormone level results that were initially misunderstood as an aggravation of the disease; there are some reports of misdiagnosis of hyperthyroidism due to biotin administration. Unexpected fluctuations in thyroid function test results in patients with GD should be checked for biotin intake, immunoassays and the limiting concentration of biotin to avoid misdiagnosis of relapse.

Development of a Japanese Scale that Evaluates the Level of Nursing Support Provided to Patients for Decision-Making in Cancer Clinical Trials.

Clinical nurses need learning programs that are useful in nursing support for patients' decision-making (NSPDM) regarding cancer clinical trials (CCTs). The usefulness of the learning program can be evaluated if the practices of NSPDM before and after participation in the learning program can be compared. We developed a scale to measure the level of self-assessed NSPDM regarding participation in a CCT. Thirty-two items of scale were developed in Japanese based on previous literature. Based on the results of a pilot study, items with similar meanings were removed and the validity of the 26 scale items was statistically examined in terms of construct validity and reliability. The study population was clinical nurses and included clinical research nurses. We received 102 valid responses from clinical nurses. Based on the bias of the boxplot distribution and the ceiling and floor effects for the items analysis of the 26-item draft scale, 17 items remained. Exploratory factor analysis (EFA) revealed that the scale consisted of three subscales and 17 items. Regarding fit indices of the model, the goodness-of-fit index (GFI), adjusted GFI (AGFI), comparative fit index (CFI), and root mean square error of application (RMSEA) were 0.775, 0.704, 0.477, and 0.081, respectively. The Cronbach's alpha coefficient for the overall scale was 0.951, with subscales ranging from 0.820 to 0.942. The validity and reliability of this scale were acceptable. This scale may be helpful to evaluate the usefulness of learning programs, i.e., the practice level of NSPDM.

ChREBP deficiency prevents high sucrose diet-induced obesity through reducing sucrase expression.

Obesity appears to be a major contributing factor for many health problems. Effective treatments for reducing weight gain, other than caloric restriction and exercise, are limited. The consumption of sugars is a major factor in the development of obesity in part by stimulating the transcription factor, carbohydrate response element binding protein (ChREBP), a process that is driven by de novo lipogenesis. Therefore, we hypothesized that inhibiting the action of ChREBP would be a promising strategy for alleviating these diseases. Using ChREBP deficient mice, the effect of a high intake of sucrose on body weight and blood glucose levels were investigated. Unlike wild type mice, ChREBP deficient mice did not gain much weight and their blood glucose and cholesterol levels remained relatively constant. In tracing it's cause, we found that the levels of expression of sucrase, an enzyme that digests sucrose, and both Glut2 and Glut5, a transporter of glucose and fructose, were not induced by feeding a high sucrose diet in the small intestine of ChREBP deficient mice. Our findings suggest that the inhibition of ChREBP could suppress weight gain even on a high sucrose diet.

A lack of ChREBP inhibits mitochondrial cristae formation in brown adipose tissue.

The carbohydrate response element binding protein (ChREBP) is a glucose-responsive transcription factor that increases the transcription of multiple genes. ChREBP is highly localized in the liver, where it upregulates the expression of genes that code for glycolytic and lipogenic enzymes, resulting in the conversion of excess carbohydrate into storage fat. ChREBP knockout (KO) mice display an anti-obese phenotype. However, at this time, role of ChREBP in adipose tissue remains unclear. Therefore, the energy metabolism and morphology of mitochondrial brown adipose tissue (BAT) in ChREBP KO mice was examined. We found increased expression levels of electron transport system proteins including the mitochondrial uncoupling protein (UCP1), and mitochondrial structural alterations such as dysplasia of the cristae and the presence of small mitochondria in BAT of ChREBP KO mice. Mass spectrometry analyses revealed that fatty acid synthase was absent in the BAT of ChREBP KO mice, which probably led to a reduction in fatty acids and cardiolipin, a regulator of various mitochondrial events. Our study clarified the new role of ChREBP in adipose tissue and its involvement in mitochondrial function. A clearer understanding of ChREBP in mitochondria could pave the way for improvements in obesity management.

Incorporating patient centered benefits as endpoints in randomized trials of maintenance therapies in advanced ovarian cancer: A position paper from the GCIG symptom benefit committee.

BACKGROUND: Quality of life and patient reported outcome measures (PROMs) are important secondary endpoints and incorporated in most contemporary clinical trials. There have been deficiencies in their assessment and reporting in ovarian cancer clinical trials, particularly in trials of maintenance treatment where they are of particular importance. The Gynecologic Cancer InterGroup (GCIG) symptom benefit committee (SBC) recently convened a brainstorming meeting with representation from all collaborative groups to address questions of how to best incorporate PROMs into trials of maintenance therapies to support the primary endpoint which is usually progression free survival (PFS). These recommendations should harmonize the collection, analysis and reporting of PROM's across future GCIG trials. METHODS: Through literature review, trials analysis and input from international experts, the SBC identified four relevant topics to address with respect to promoting the role of PROMs to support the PFS endpoint in clinical trials of maintenance treatment for OC. RESULTS: The GCIG SBC unanimously accepted the importance of integrating PROM's in future maintenance trials and developed four guiding principles to be considered early in trial design. These include 1) adherence to SPIRIT-PRO guidelines, 2) harmonization of selection, collection and reporting of PROM's; 3) combining Health Related Quality of Life (HRQL) measures with clinical endpoints and 4) common approaches to dealing with incomplete HRQL data. CONCLUSIONS: Close attention to incorporating HRQL and PROM's is critical to interpret the results of ovarian cancer clinical trials of maintenance therapies. There should be a consistent approach to assessing and reporting patient centered benefits across all GCIG trials to enable cross trial comparisons which can be used to inform practice.

Assessment of Adherence to Post-exposure Prophylaxis with Oseltamivir in Healthcare Workers: A Retrospective Questionnaire-Based Study.

Post-exposure prophylaxis (PEP) for healthcare workers is one of the effective strategies for preventing nosocomial outbreaks of influenza. However, PEP adherence in healthcare workers is rarely analysed, and no strategies have been established to improve adherence to PEP for healthcare workers. We aimed to retrospectively analyse adherence to PEP and the factors associated with non-adherence in healthcare workers. A survey of 221 healthcare workers who were eligible for PEP at Tokushima University Hospital in the 2016/2017 season was conducted. Once-daily oseltamivir (75 mg for 10 d) was used as the PEP regimen. Of the 221 healthcare workers, 175 received PEP and were surveyed for adherence using a questionnaire. Of the 130 healthcare workers who responded to the questionnaire, 121 (93.1%) had been vaccinated. In this survey, 82 healthcare workers (63.1%) did not fully complete PEP. Multiple logistic regression analysis revealed that physicians (odds ratio: 4.62, 95% confidence interval [CI]: 2.08-10.25) and non-vaccination (odds ratio: 9.60, 95% CI: 1.12-82.25) were the factors for non-adherence to PEP. Of the 47 healthcare workers who responded to the item regarding reasons for non-adherence, 36 (76.6%) reported forgetting to take oseltamivir or discontinuing it due to a misguided self-decision that continuation of PEP was unnecessary, and 5 (10.6%) reported discontinuing treatment due to adverse effects. In conclusion, healthcare workers, particularly physicians, had low PEP adherence owing to forgetting or stopping to take oseltamivir due to a misguided self-decision. To obtain the maximum preventive effect of PEP, medication education should be provided to endorse PEP compliance.

The efficacy of specialised rehabilitation using the Op-reha Guide for cancer patients in palliative care units: protocol of a multicentre, randomised controlled trial (JORTC-RHB02).

BACKGROUND: Although rehabilitation is recommended for terminal cancer patients, the specific components and methods of such programs are poorly documented. No studies to date have examined the effectiveness of rehabilitation for terminal cancer patients. This study aims to evaluate the efficacy of a new intervention for rehabilitation therapists, using the Op-reha Guide (Guide to Optimal and Patient-Centred Rehabilitation Practice for Patients in Palliative Care Units [PCUs]) in rehabilitation practice. This guide consists of recommended actions and attitudes for rehabilitation therapists and aims to optimise therapists' actions according to the patient's needs and condition. It shares goals with terminal cancer patients to maintain their activities of daily living (ADL). METHODS: This study uses a multicentre, prospective, randomised controlled trial (RCT) design with two parallel groups in PCUs where specialised rehabilitation will be routinely performed for terminal cancer patients by rehabilitation therapists. Participants will be randomised (1:1) to intervention (the Op-reha Guide) and control groups (usual rehabilitation). We will then conduct an observational study in PCUs that do not perform specialised rehabilitation for terminal cancer patients; this will be considered the usual care group, and the efficacy of usual rehabilitation will be quantitatively evaluated. Inclusion criteria are hospitalisation in PCU, European Cooperative Oncology Group Performance Status of 2 or 3, and clinical estimation of life expectancy of 3 weeks or more. Patients with severe symptom burden will be excluded. We hypothesise that the Op-reha Guide will be more effective in maintaining the ADL of terminal cancer patients hospitalised in PCUs than usual rehabilitation. The primary endpoint is defined as the change in (total) modified Barthel Index from baseline to Day 22. Quality of life will be a secondary endpoint. In total, 135 patients will be recruited from 16 Japanese sites between July 2019 and December 2021. DISCUSSION: This will be the first trial to evaluate the efficacy of specialised rehabilitation for terminal cancer patients hospitalised in PCUs, and will contribute to the evidence on the efficacy of implementing rehabilitation for terminal cancer patients. TRIAL REGISTRATION: UMIN-CTR, UMIN000037298 R000042525 (date of registration 7 July 2019).

A cysteine residue affects the conformational state and neuronal toxicity of mutant SOD1 in mice: relevance to the pathogenesis of ALS.

We previously showed by in vitro experiments that the cysteine residue (Cys111) near the dimer interface is critical for monomerization and resultant aggregate formation of mutant Cu, Zn-superoxide dismutase (SOD1) protein, which is toxic to motor neurons in familial amyotrophic lateral sclerosis (ALS). To verify the importance of Cys111 in the mutant SOD1-associated ALS pathogenesis in vivo, we analyzed the disease phenotype of SOD1 transgenic mice harboring H46R mutation alone (H46R mice) or H46R/C111S double mutations (H46R/C111S mice). Behavioral, histological and biochemical analyses of the spinal cord showed that the onset and progression of the disease phenotype were delayed in H46R/C111S mice compared with H46R mice. We found that peroxidized Cys111 of H46R SOD1 plays a role in promoting formation of high molecular weight insoluble SOD1 species that is correlated with the progression of the motor neuron disease phenotype. These results support that Cys111 is a critical residue for the neuronal toxicity of mutant SOD1 in vivo, and the blockage of peroxidation of this residue in mutant SOD1 may constitute a future target for developing ALS treatment.

Outbreaks of influenza B infection and pneumococcal pneumonia at a mental health facility in Japan.

BACKGROUND: Japan has an aging population and an increasing number of patients who reside in long-term care and mental health facilities. Both pneumococcal pneumonia and influenza B infection outbreaks have been observed in these populations, although no reports have described concurrent outbreaks of pneumococcal pneumonia and influenza B infection in these facilities. CASE PRESENTATION: Six patients and two staffs were initially diagnosed with influenza B infection at a mental health facility on March 14, 2015. By March 21, influenza B infection was diagnosed in 26 patients and 10 staff; all individuals received anti-influenza drugs. On March 19, two patients were diagnosed with pneumococcal pneumonia, and seven patients had developed pneumococcal pneumonia by March 24. Six of these seven patients also had influenza B infection. All individuals who developed pneumococcal pneumonia were hospitalized and treated using ampicillin/sulbactam at our hospital, and their symptoms subsequently subsided. Among the seven pneumococcal strains that were frozen and stored, two strains were type 3 and five strains were type 11A/E. Pulsed-field gel electrophoresis testing revealed that each of the serum types were from the same clone. CONCLUSION: It appears that an outbreak of influenza B infection was followed by the spread of multi-clone pneumococcal pneumonia among elderly patients at a mental health facility. Therefore, it may be prudent to use vaccinations to prevent the spread of pneumococcal pneumonia among elderly patients and this diagnosis should be actively considered during outbreaks of influenza infection at elder care facilities.

Anemia attributed to vitamin B6 deficiency in post-pancreaticoduodenectomy patients.

Micronutrient deficiencies such as vitamin A, iron, zinc, and selenium have been known to occur as a consequence of pancreaticoduodenectomy (PD), but vitamin B6 deficiency has not been previously reported. We report two post-PD patients who developed anemias attributed to vitamin B6 deficiency. Oral supplementations of vitamin B6 significantly improved anemias in both cases. Micronutrients including vitamin B6 should be monitored in post-PD patients, and supplementations should be carried out when necessary.

Aberrant assembly of RNA recognition motif 1 links to pathogenic conversion of TAR DNA-binding protein of 43 kDa (TDP-43).

Aggregation of TAR DNA-binding protein of 43 kDa (TDP-43) is a pathological signature of amyotrophic lateral sclerosis (ALS). Although accumulating evidence suggests the involvement of RNA recognition motifs (RRMs) in TDP-43 proteinopathy, it remains unclear how native TDP-43 is converted to pathogenic forms. To elucidate the role of homeostasis of RRM1 structure in ALS pathogenesis, conformations of RRM1 under high pressure were monitored by NMR. We first found that RRM1 was prone to aggregation and had three regions showing stable chemical shifts during misfolding. Moreover, mass spectrometric analysis of aggregated RRM1 revealed that one of the regions was located on protease-resistant ß-strands containing two cysteines (Cys-173 and Cys-175), indicating that this region served as a core assembly interface in RRM1 aggregation. Although a fraction of RRM1 aggregates comprised disulfide-bonded oligomers, the substitution of cysteine(s) to serine(s) (C/S) resulted in unexpected acceleration of amyloid fibrils of RRM1 and disulfide-independent aggregate formation of full-length TDP-43. Notably, TDP-43 aggregates with RRM1-C/S required the C terminus, and replicated cytopathologies of ALS, including mislocalization, impaired RNA splicing, ubiquitination, phosphorylation, and motor neuron toxicity. Furthermore, RRM1-C/S accentuated inclusions of familial ALS-linked TDP-43 mutants in the C terminus. The relevance of RRM1-C/S-induced TDP-43 aggregates in ALS pathogenesis was verified by immunolabeling of inclusions of ALS patients and cultured cells overexpressing the RRM1-C/S TDP-43 with antibody targeting misfolding-relevant regions. Our results indicate that cysteines in RRM1 crucially govern the conformation of TDP-43, and aberrant self-assembly of RRM1 at amyloidogenic regions contributes to pathogenic conversion of TDP-43 in ALS.

Differences in Fentanyl Requirements in Terminally Ill Cancer Patients.

Cancer pain is a significant issue in terminally ill cancer patients (TICPs). The fentanyl patch (FP) is used extensively for treating cancer pain, but FP requirements vary between patients. We aimed to identify determinants of FP requirements in TICPs and propose effective pain relief using a FP. In a retrospective chart review, we investigated cancer patients admitted to our hospital from April 2012 to July 2015 and used FP until death. The time course of FP use in TICPs until death was examined. The primary endpoint was the final dose of FP use (FDFP). In total, 79 patients were included the analysis. FDFP was inversely correlated with age (R= -0.262, p = 0.20; Spearman test). FDFP tended to be higher in males than in females and was significantly higher in patients with pancreatic cancer than in patients without pancreatic cancer (p = 0.017; Welch's test). FP adjustments were more frequent in the last 60 days of life in patients with pancreatic cancer than in patients with other malignancies (P for interaction = 0.002; mixed effect model). In conclusion, younger age, and pancreatic cancer were associated with higher FP requirements in TICPs. TICPs with pancreatic cancer required more frequent FP adjustment near death.

Efficacy of oligodendrocyte precursor cells as delivery vehicles for single-chain variable fragment to misfolded SOD1 in ALS rat model.

Superoxide dismutase1 (SOD 1) mutation is a leading cause of familial amyotrophic lateral sclerosis (ALS). Growing evidence suggests that antibody therapy against misfolded SOD1 protein can be therapeutic. However, the therapeutic effects are limited, partly because of the delivery system. Therefore, we investigated the efficacy of oligodendrocyte precursor cells (OPCs) as a drug delivery vehicle of single-chain variable fragments (scFv). Using a Borna disease virus vector that is pharmacologically removable and episomally replicable in the recipient cells, we successfully transformed wild-type OPCs to secrete scFv of a novel monoclonal antibody (D3-1), specific for misfolded SOD1. Single intrathecal injection of OPCs scFvD3-1, but not OPCs alone, significantly delayed disease onset and prolonged the lifespan of ALS rat models expressing SOD1 H46R . The effect of OPC scFvD3-1 surpassed that of a 1 month intrathecal infusion of full-length D3-1 antibody alone. scFv-secreting OPCs suppressed neuronal loss and gliosis, reduced levels of misfolded SOD1 in the spinal cord, and suppressed the transcription of inflammatory genes, including Olr1, an oxidized low-density lipoprotein receptor 1. The use of OPCs as a delivery vehicle for therapeutic antibodies is a new option for ALS in which misfolded protein and oligodendrocyte dysfunction are implicated in the pathogenesis.

Left lobe adult-to-adult living donor liver transplantation: Should portal inflow modulation be added?

Recently, the successful application of portal inflow modulation has led to renewed interest in the use of left lobe grafts in adult-to-adult living donor liver transplantation (LDLT). However, data on the hepatic hemodynamics supporting portal inflow modulation are limited, and the optimal portal circulation for a liver graft is still unclear. We analyzed 42 consecutive adult-to-adult left lobe LDLT cases without splenectomy or a portocaval shunt. The mean actual graft volume (GV)/recipient standard liver volume (SLV) ratio was 39.8% ± 5.7% (median = 38.9%, range = 26.1%-54.0%). The actual GV/SLV ratio was less than 40% in 24 of the 42 cases, and the actual graft-to-recipient weight ratio was less than 0.8% in 17 of the 42 recipients. The mean portal vein pressure (PVP) was 23.9 ± 7.6 mm Hg (median = 23.5 mm Hg, range = 9-38 mm Hg) before transplantation and 21.5 ± 3.6 mm Hg (median = 22 mm Hg, range = 14-27 mm Hg) after graft implantation. The mean portal pressure gradient (PVP - central venous pressure) was 14.5 ± 6.8 mm Hg (median = 13.5 mm Hg, range = 3-26 mm Hg) before transplantation and 12.4 ± 4.4 mm Hg (median = 13 mm Hg, range = 1-21 mm Hg) after graft implantation. The mean posttransplant portal vein flow was 301 ± 167 mL/minute/100 g of liver in the 38 recipients for whom it was measured. None of the recipients developed small-for-size syndrome, and all were discharged from the hospital despite portal hyperperfusion. The overall 1-, 3-, and 5-year patient and graft survival rates were 100%, 97%, and 91%, respectively. In conclusion, LDLT with a left liver graft without splenectomy or a portocaval shunt yields good long-term results for adult patients with a minimal donor burden.

Oxidative modification of cysteine 111 promotes disulfide bond-independent aggregation of SOD1.

Converging evidence indicates that SOD1 aggregation is a common feature of mutant SOD1-linked fALS, and seems to be directly related to the gain-of-function toxic property. However, the mechanism inducing the aggregation is not understood. To study the contribution of oxidative modification of cysteine residues in SOD1 aggregation, we systematically examined the redox state of SOD1 cysteine residues in the G37R transgenic mouse model at different stages of the disease and under oxidative stress induced by H2O2. Our data suggest that under normal circumstance, cysteine 111 residue in SOD1 is free; however, under oxidative stress, it is prone to oxidative modification by providing the thiolate anion (S-). With the progression of the disease, increased levels of oxidative insults facilitated the oxidation of thiol groups of cysteine residues; human mutant SOD1 could generate an upper shift band in reducing SDS-PAGE, which turned out to be a Cys111-peroxidized SOD1 species. We also detected the formation of SOD1 multimers at different stages of the disease, and found that accumulated oxidative stress facilitated the formation of aggregates, which were not mediated by disulfide bond. This oxidative modification of cysteine 111 therefore promotes the formation of disulfide bond-independent aggregation of SOD1.

A foodborne outbreak of sapovirus linked to catered box lunches in Japan.

Sapovirus (SaV) is a common cause of acute viral gastroenteritis worldwide, and SaV outbreaks have become more frequent in recent years. In January 2010, an outbreak of acute gastroenteritis due to SaV occurred in Aichi, Gifu and Mie Prefectures, Japan. The illness was strongly associated with eating a delivered box lunch prepared by one catering company. In total, 655 (17.1 %) of 3827 individuals developed gastroenteritic symptoms. SaV was detected in seven of the nine people who became ill and in seven of the 52 food handlers at the catering company, but all the tested samples were negative for norovirus and enteropathogenic bacteria. Sequence analysis of RT-PCR products indicated that the nucleotide sequences of SaV strains from the people who became ill and the food handlers were identical. The detected SaV strains were genogrouped as SaV genotype I.2. This was the largest foodborne outbreak of sapovirus in Japan.

Iron deficiency aggravates DMNQ-induced cytotoxicity via redox cycling in kidney-derived cells.

Iron, an essential element for most of living organisms, participates in many biological functions. Since iron is redox-active transition metal, it is known that excessive levels stimulate the formation of reactive oxygen species (ROS) and exacerbate cytotoxicity. An iron deficiency is the most common nutritional deficiency disorder in the world (about 30% of the population) and is more common than cases of iron overload. However, the effects of iron deficiency on ROS-induced cytotoxicity and the maintenance of intracellular redox homeostasis are not fully understood. The present study reports on an evaluation of the effects of iron deficiency on cytotoxicity induced by several ROS generators. In contrast to hydrogen peroxide and erastin, the cytotoxicity of 2,3-dimethoxy-1,4-naphthoquinone (DMNQ), a redox cycling agent that induces intracellular superoxide anion formation, was exacerbated by iron deficiency. Cytochrome b5 reductase was identified as a candidate enzyme responsible for the redox cycling of DMNQ under conditions of iron depletion. Moreover, the DMNQ-induced intracellular accumulation of ROS and a decrease in NADH/NAD+ ratios were enhanced by an iron deficiency. These negative changes were found to be ameliorated by overexpressing NAD(P)H:quinone oxidoreductase 1 (NQO1) in kidney-derived cells that originally showed a very low expression of NQO1. These results indicate that NQO1 plays a protective role against redox cycling quinone-mediated cytotoxicity under iron-depleted conditions. This is because NQO1 generates less-toxic hydroquinones via the two-electron reduction of quinones. The collective findings reported herein demonstrate that not only an iron overload but also an iron deficiency exacerbates ROS-mediated cytotoxicity.