Protective effect of sulforaphane against cisplatin-induced mitochondrial alterations and impairment in the activity of NAD(P)H: Quinone oxidoreductase 1 and γ glutamyl cysteine ligase: Studies in mitochondria isolated from rat kidney and in LLC-PK1 cells

Sulforaphane Restores Mitochondrial β-Oxidation and Reduces Renal Lipid Accumulation in a Model of Releasing Unilateral Ureteral Obstruction

Obstructive nephropathy (ON), characterized by urine flow disruption, can induce chronic kidney disease (CKD). Although the release of the obstruction is performed as the primary intervention, renal pathology often persists and progresses. Accordingly, the murine model of releasing unilateral ureteral obstruction (RUUO) is valuable for investigating the molecular events underlying renal damage after obstruction release. Remarkably, after RUUO, disturbances such as oxidative stress, inflammation, lipid accumulation, and fibrosis continue to increase. Mitochondrial dysfunction contributes to fibrosis in the UUO model, but its role in RUUO remains unclear. Additionally, the impact of using antioxidants to restore mitochondrial function and prevent renal fibrosis in RUUO has not been determined. This study aimed to determine the therapeutic effect of pre-administering the antioxidant sulforaphane (SFN) in the RUUO model. SFN was administered 1 day before RUUO to evaluate mitochondrial biogenesis, fatty acids (FA) metabolism, bioenergetics, dynamics, and mitophagy/autophagy mechanisms in the kidney. Our data demonstrated that SFN enhanced mitochondrial biogenesis and reestablished mitochondrial oxygen consumption and β-oxidation. These effects collectively reduced lipid accumulation and normalized mitochondrial dynamics, mitophagy, and autophagy, thereby mitigating fibrosis after obstruction. Our findings suggest that SFN holds promise as a potential therapeutic agent in ON-induced CKD progression in RUUO and opens new avenues in studying antioxidant molecules to treat this disease.

Sulforaphane and ophthalmic diseases

Sulforaphane (SFN) is an organosulfur compound categorized as an isothiocyanate (ITC), primarily extracted from cruciferous vegetables like broccoli and cabbage. The molecular formula of sulforaphane (SFN) is C6H11NOS2. SFN is generated by the hydrolysis of glucoraphanin (GRP) through the enzyme myrosinase, showing notable properties including anti-diabetic, anti-inflammatory, antimicrobial, anti-angiogenic, and anticancer attributes. Ongoing clinical trials are investigating its potential in diseases such as cancer, neurodegenerative diseases, diabetes-related complications, chronic kidney disease, cardiovascular disease, and liver diseases. Several animal carcinogenesis models and cell culture models have shown it to be a very effective chemopreventive agent, and the protective effects of SFN in ophthalmic diseases have been linked to multiple mechanisms. In murine models of diabetic retinopathy and age-related macular degeneration, SFN delays retinal photoreceptor cell degeneration through the Nrf2 antioxidative pathway, NF-κB pathway, AMPK pathway, and Txnip/mTOR pathway. In rabbit models of keratoconus and cataract, SFN has been shown to protect corneal and lens epithelial cells from oxidative stress injury by activating the Keap1-Nrf2-ARE pathway and the Nrf-2/HO-1 antioxidant pathway. Oral delivery or intraperitoneal injection at varying concentrations are the primary strategies for SFN intake in current preclinical studies. Challenges remain in the application of SFN in eye disorders due to its weak solubility in water and limited bioavailability because of the presence of blood-ocular barrier systems. This review comprehensively outlines recent research on SFN, elucidates its mechanisms of action, and discusses potential therapeutic benefits for eye disorders such as age-related macular degeneration (AMD), diabetic retinopathy (DR), cataracts, and other ophthalmic diseases, while also indicating directions for future clinical research to achieve efficient SFN treatment for ophthalmic diseases.

The underlying mechanisms of cisplatin-induced nephrotoxicity and its therapeutic intervention using natural compounds

Cisplatin is an effective chemotherapeutic drug widely used for the treatment of various solid tumors; however, its clinical use and efficacy are limited by its inherent nephrotoxicity. The pathogenesis of cisplatin-induced nephrotoxicity is complex and has not been fully elucidated. Cellular uptake and transport, DNA damage, apoptosis, oxidative stress, inflammatory response, and autophagy are involved in the development of cisplatin-induced nephrotoxicity. Currently, despite some deficiencies, hydration regimens remain the major protective measures against cisplatin-induced nephrotoxicity. Therefore, effective drugs must be explored and developed to prevent and treat cisplatin-induced kidney injury. In recent years, many natural compounds with high efficiency and low toxicity have been identified for the treatment of cisplatin-induced nephrotoxicity, including quercetin, saikosaponin D, berberine, resveratrol, and curcumin. These natural agents have multiple targets, multiple effects, and low drug resistance; therefore, they can be safely used as a supplementary regimen or combination therapy for cisplatin-induced nephrotoxicity. This review aimed to comprehensively describe the molecular mechanisms underlying cisplatin-induced nephrotoxicity and summarize natural kidney-protecting compounds to provide new ideas for the development of better therapeutic agents.

Sulforaphane alleviates the meiosis defects induced by 3-nitropropionic acid in mouse oocytes

3-Nitropropionic acid (3-NP) is a mycotoxin commonly found in plants and fungi that has been linked to mammalian intoxication. Previously, we found 3-NP treatment exhibited reproductive toxicity by inducing oxidative stress in mouse ovary; however, the toxic effects of 3-NP on mouse oocyte maturation have not been investigated. Sulforaphane (SFN) is a naturally bioactive phytocompound derived from cruciferous vegetables that has been shown to possess cytoprotective properties. The present study was designed to investigate the cytotoxicity of 3-NP during mouse oocyte maturation and the protective effects of SFN on oocytes challenged with 3-NP. The results showed 3-NP had a dose-dependent inhibitory effect on oocyte maturation, and SFN significantly alleviated the defects caused by 3-NP, including failed first polar body extrusion and abnormal spindle assembly. Furthermore, 3-NP caused abnormal mitochondrial distribution in oocytes and disrupted mitochondrial functions, including mitochondrial depolarization, decreased ATP levels, and increased mitochondrial-derived ROS. Finally, 3-NP induced oxidative stress in oocytes, leading to increased apoptosis and autophagy, while SFN supplementation had significant cytoprotective effects on these damages. Collectively, our results provide insight on the mechanism of 3-NP toxicity in mouse oocytes and suggest the application of SFN may be a viable intervention strategy to mitigate 3-NP-induced reproductive toxicity.

Sulforaphane exhibits potent renoprotective effects in preclinical models of kidney diseases: A systematic review and meta-analysis

AIMS

Sulforaphane (SFN), a naturally occurring isothiocyanate found in cruciferous vegetables, has received extensive attention as a natural activator of the Nrf2/Keap1 cytoprotective pathway. In this review, a meta-analysis and systematic review of the renoprotective effects of SFN were performed in various preclinical models of kidney diseases.

MAIN METHODS

The primary outcome was the impact of SFN on renal function biomarkers (uremia, creatininemia, proteinuria or creatinine clearance) and secondary outcomes were kidney lesion histological indices/kidney injury molecular biomarkers. The effects of SFN were evaluated according to the standardized mean differences (SMDs). A random-effects model was applied to estimate the overall summary effect.

KEY FINDINGS

Twenty-five articles (out of 209 studies) were selected from the literature. SFN administration significantly increased creatinine clearance (SMD +1.88 95 % CI: [1.09; 2.68], P < 0.0001, I² = 0 %) and decreased the plasma creatinine (SMD -1.24, [-1.59; -0.88], P < 0.0001, I² = 36.0 %) and urea (SMD -3.22 [-4.42, -2.01], P < 0.0001, I² = 72.4 %) levels. SFN administration (median dose: 2.5 mg/kg, median duration: 3 weeks) significantly decreased urinary protein excretion (SMD -2.20 [-2.68; -1.73], P < 0.0001, I² = 34.1 %). It further improved two kidney lesion histological indices namely kidney fibrosis (SMD -3.08 [-4.53; -1.63], P < 0.0001, I² = 73.7 %) and glomerulosclerosis (SMD -2.24 [-2.96; -1.53], P < 0.0001, I² = 9.7 %) and decreased kidney injury molecular biomarkers (SMD -1.51 [-2.00; -1.02], P < 0.0001, I² = 0 %).

SIGNIFICANCE

These findings provide new insights concerning preclinical strategies for treating kidney disease or kidney failure with SFN supplements and should stimulate interest in clinical evaluations of SFN in patients with kidney disease.

Ameliorative impacts of polymeric and metallic nanoparticles on cisplatin-induced nephrotoxicity: a 2011-2022 review

Cisplatin (CDDP) is a well-known platinum-based drug used in the treatment of various malignancies. However, the widespread side effects that this drug leaves on normal tissues make its use limited. Since cisplatin is mainly eliminated from the kidneys, CDDP-induced nephrotoxicity is the most significant dose-limiting complication attributed to cisplatin, which often leads to dose withdrawal. Considering the high efficiency of cisplatin in chemotherapy, finding renoprotective drug delivery systems for this drug is a necessity. In this regard, we can take advantages of different nanoparticle-based approaches to deliver cisplatin into tumors either using passive targeting or using specific receptors. In an effort to find more effective cisplatin-based nano-drugs with less nephrotoxic effect, the current 2011-2022 review study was conducted to investigate some of the nanotechnology-based methods that have successfully been able to mitigate CDDP-induced nephrotoxicity. Accordingly, although cisplatin can cause renal failures through inducing mitochondria dysfunction, oxidative stress, lipid peroxidation and endoplasmic reticulum stress, some CDDP-based nano-carriers have been able to reverse a wide range of these advert effects. Based on the obtained results, it was found that the use of different metallic and polymeric nanoparticles can help renal cells to strengthen their antioxidant systems and stay alive through reducing CDDP-induced ROS generation, inhibiting apoptosis-related pathways and maintaining the integrity of the mitochondrial membrane. For example, nanocurcumin could inhibit oxidative stress and acting as a ROS scavenger. CONPs could reduce lipid peroxidation and pro-inflammatory cytokines. CDDP-loaded silver nanoparticles (AgNPs) could inhibit mitochondria-mediated apoptosis. In addition, tea polyphenol-functionalized SeNPs (Se@TE) NPs could mitigate the increased level of dephosphorylated AKT, phosphorylated p38 MAPK and phosphorylated c-Jun N-terminal kinase (JNK) induced by cisplatin. Moreover, exosomes mitigated cisplatin-induced renal damage through inhibiting Bcl2 and increasing Bim, Bid, Bax, cleaved caspase-9, and cleaved caspase-3. Hence, nanoparticle-based techniques are promising drug delivery systems for cisplatin so that some of them, such as lipoplatins and nanocurcumins, have even reached phases 1-3 trials.

Sulforaphane Protects against Unilateral Ureteral Obstruction-Induced Renal Damage in Rats by Alleviating Mitochondrial and Lipid Metabolism Impairment

Unilateral ureteral obstruction (UUO) is an animal rodent model that allows the study of obstructive nephropathy in an accelerated manner. During UUO, tubular damage is induced, and alterations such as oxidative stress, inflammation, lipid metabolism, and mitochondrial impairment favor fibrosis development, leading to chronic kidney disease progression. Sulforaphane (SFN), an isothiocyanate derived from green cruciferous vegetables, might improve mitochondrial functions and lipid metabolism; however, its role in UUO has been poorly explored. Therefore, we aimed to determine the protective effect of SFN related to mitochondria and lipid metabolism in UUO. Our results showed that in UUO SFN decreased renal damage, attributed to increased mitochondrial biogenesis. We showed that SFN augmented peroxisome proliferator-activated receptor γ co-activator 1α (PGC-1α) and nuclear respiratory factor 1 (NRF1). The increase in biogenesis augmented the mitochondrial mass marker voltage-dependent anion channel (VDAC) and improved mitochondrial structure, as well as complex III (CIII), aconitase 2 (ACO2) and citrate synthase activities in UUO. In addition, lipid metabolism was improved, observed by the downregulation of cluster of differentiation 36 (CD36), sterol regulatory-element binding protein 1 (SREBP1), fatty acid synthase (FASN), and diacylglycerol O-acyltransferase 1 (DGAT1), which reduces triglyceride (TG) accumulation. Finally, restoring the mitochondrial structure reduced excessive fission by decreasing the fission protein dynamin-related protein-1 (DRP1). Autophagy flux was further restored by reducing beclin and sequestosome (p62) and increasing B-cell lymphoma 2 (Bcl2) and the ratio of microtubule-associated proteins 1A/1B light chain 3 II and I (LC3II/LC3I). These results reveal that SFN confers protection against UUO-induced kidney injury by targeting mitochondrial biogenesis, which also improves lipid metabolism.

Nrf2 Activation in Chronic Kidney Disease: Promises and Pitfalls

The nuclear factor erythroid 2-related factor 2 (Nrf2) protects the cell against oxidative damage. The Nrf2 system comprises a complex network that functions to ensure adequate responses to redox perturbations, but also metabolic demands and cellular stresses. It must be kept within a physiologic activity range. Oxidative stress and alterations in Nrf2-system activity are central for chronic-kidney-disease (CKD) progression and CKD-related morbidity. Activation of the Nrf2 system in CKD is in multiple ways related to inflammation, kidney fibrosis, and mitochondrial and metabolic effects. In human CKD, both endogenous Nrf2 activation and repression exist. The state of the Nrf2 system varies with the cause of kidney disease, comorbidities, stage of CKD, and severity of uremic toxin accumulation and inflammation. An earlier CKD stage, rapid progression of kidney disease, and inflammatory processes are associated with more robust Nrf2-system activation. Advanced CKD is associated with stronger Nrf2-system repression. Nrf2 activation is related to oxidative stress and moderate uremic toxin and nuclear factor kappa B (NF-κB) elevations. Nrf2 repression relates to high uremic toxin and NF-κB concentrations, and may be related to Kelch-like ECH-associated protein 1 (Keap1)-independent Nrf2 degradation. Furthermore, we review the effects of pharmacological Nrf2 activation by bardoxolone methyl, curcumin, and resveratrol in human CKD and outline strategies for how to adapt future Nrf2-targeted therapies to the requirements of patients with CKD.

Natural products: potential treatments for cisplatin-induced nephrotoxicity

Cisplatin is a clinically advanced and highly effective anticancer drug used in the treatment of a wide variety of malignancies, such as head and neck, lung, testis, ovary, breast cancer, etc. However, it has only a limited use in clinical practice due to its severe adverse effects, particularly nephrotoxicity; 20%–35% of patients develop acute kidney injury (AKI) after cisplatin administration. The nephrotoxic effect of cisplatin is cumulative and dose dependent and often necessitates dose reduction or withdrawal. Recurrent episodes of AKI result in impaired renal tubular function and acute renal failure, chronic kidney disease, uremia, and hypertensive nephropathy. The pathophysiology of cisplatin-induced AKI involves proximal tubular injury, apoptosis, oxidative stress, inflammation, and vascular injury in the kidneys. At present, there are no effective drugs or methods for cisplatin-induced kidney injury. Recent in vitro and in vivo studies show that numerous natural products (flavonoids, saponins, alkaloids, polysaccharide, phenylpropanoids, etc.) have specific antioxidant, anti-inflammatory, and anti-apoptotic properties that regulate the pathways associated with cisplatin-induced kidney damage. In this review we describe the molecular mechanisms of cisplatin-induced nephrotoxicity and summarize recent findings in the field of natural products that undermine these mechanisms to protect against cisplatin-induced kidney damage and provide potential strategies for AKI treatment.

Three in One: The Potential of Brassica By-Products against Economic Waste, Environmental Hazard, and Metabolic Disruption in Obesity

A large amount of waste is generated within the different steps of the food supply chain, representing a significant loss of natural resources, plant material, and economic value for producers and consumers. During harvesting and processing, many parts of edible plants are not sold for consumption and end up as massive waste, adding environmental hazards to the list of concerns regarding food wastage. Examples are Brassica oleracea var. Italica (broccoli) by-products, which represent 75% of the plant mass. A growing concern in the Western world is obesity, which results from incorrect lifestyles and comprises an extensive array of co-morbidities. Several studies have linked these co-morbidities to increased oxidative stress; thus, naturally occurring and readily available antioxidant compounds are an attractive way to mitigate metabolic diseases. The idea of by-products selected for their biomedical value is not novel. However, there is innovation underlying the use of Brassica by-products in the context of obesity. For this reason, Brassica by-products are prime candidates to be used in the treatment of obesity due to its bioactive compounds, such as sulforaphane, which possess antioxidant activity. Here, we review the economic and health potential of Brassica bioactive compounds in the context of obesity.

Eat Your Broccoli: Oxidative Stress, NRF2, and Sulforaphane in Chronic Kidney Disease

The mainstay of therapy for chronic kidney disease is control of blood pressure and proteinuria through the use of angiotensin-converting enzyme inhibitors (ACE-Is) or angiotensin receptor blockers (ARBs) that were introduced more than 20 years ago. Yet, many chronic kidney disease (CKD) patients still progress to end-stage kidney disease—the ultimate in failed prevention. While increased oxidative stress is a major molecular underpinning of CKD progression, no treatment modality specifically targeting oxidative stress has been established clinically. Here, we review the influence of oxidative stress in CKD, and discuss regarding the role of the Nrf2 pathway in kidney disease from studies using genetic and pharmacologic approaches in animal models and clinical trials. We will then focus on the promising therapeutic potential of sulforaphane, an isothiocyanate derived from cruciferous vegetables that has garnered significant attention over the past decade for its potent Nrf2-activating effect, and implications for precision medicine.

Cruciferous vegetables: rationale for exploring potential salutary effects of sulforaphane-rich foods in patients with chronic kidney disease

Sulforaphane (SFN) is a sulfur-containing isothiocyanate found in cruciferous vegetables (Brassicaceae) and a well-known activator of nuclear factor-erythroid 2-related factor 2 (Nrf2), considered a master regulator of cellular antioxidant responses. Patients with chronic diseases, such as diabetes, cardiovascular disease, cancer, and chronic kidney disease (CKD) present with high levels of oxidative stress and a massive inflammatory burden associated with diminished Nrf2 and elevated nuclear transcription factor-κB-κB expression. Because it is a common constituent of dietary vegetables, the salutogenic properties of sulforaphane, especially it’s antioxidative and anti-inflammatory properties, have been explored as a nutritional intervention in a range of diseases of ageing, though data on CKD remain scarce. In this brief review, the effects of SFN as a senotherapeutic agent are described and a rationale is provided for studies that aim to explore the potential benefits of SFN-rich foods in patients with CKD.

First Evidence of a Protective Effect of Plant Bioactive Compounds against H2O2-Induced Aconitase Damage in Durum Wheat Mitochondria

In order to contribute to the understanding of the antioxidant behavior of plant bioactive compounds with respect to specific subcellular targets, in this study, their capability to protect aconitase activity from oxidative-mediated dysfunction was evaluated for the first time in plant mitochondria. Interest was focused on the Krebs cycle enzyme catalyzing the citrate/isocitrate interconversion via cis-aconitate, as it possesses a [4Fe-4S]²⁺ cluster at the active site, making it an early and highly sensitive target of reactive oxygen species (ROS)-induced oxidative damage. In particular, the effect on the aconitase reaction of five natural phenols, including ferulic acid, apigenin, quercetin, resveratrol, and curcumin, as well as of the isothiocyanate sulforaphane, was investigated in highly purified mitochondria obtained from durum wheat (DWM). Interestingly, a short-term (10 min) DWM pre-treatment with all investigated compounds, applied at 150 µM (75 µM in the case of resveratrol), completely prevented aconitase damage induced by a 15 min exposure of mitochondria to 500 µM H₂O₂. Curcumin and quercetin were also found to completely recover DWM-aconitase activity when phytochemical treatment was performed after H₂O₂ damage. In addition, all tested phytochemicals (except ferulic) induced a significant increase of aconitase activity in undamaged mitochondria. On the contrary, a relevant protective and recovery effect of only quercetin treatment was observed in terms of the aconitase activity of a commercial purified mammalian isoform, which was used for comparison. Overall, the results obtained in this study may suggest a possible role of phytochemicals in preserving plant mitochondrial aconitase activity, as well as energy metabolism, against oxidative damage that may occur under environmental stress conditions. Further investigations are needed to elucidate the physiological role and the mechanism responsible for this short-term protective effect.

Altered proximal tubule fatty acid utilization, mitophagy, fission and supercomplexes arrangement in experimental Fanconi syndrome are ameliorated by sulforaphane-induced mitochondrial biogenesis

The kidney proximal tubule function relies on oxidative phosphorylation (OXPHOS), thus mitochondrial dysfunction is characteristic of acute kidney injury (AKI). Maleic acid (MA) can induce an experimental model of Fanconi syndrome that is associated to oxidative stress and decreased oxygen consumption. Sulforaphane (SF) is an antioxidant known to protect against MA-induced AKI. The molecular basis by which SF maintains the bioenergetics in MA-induced AKI is not fully understood. To achieve it, rats were submitted to a protective scheme: SF (1 mg/kg/day i.p.) for four days and, at the fourth day, they received a single dose of MA (400 mg/kg i.p.), getting four main experimental groups: (1) control (CT), (2) MA-nephropathy (MA), (3) SF-protected and (4) SF-control (SF). Additionally, a similar protective schema was tested in cultured NRK-52E cells with different concentrations of SF and MA. In the animal model, SF prevented the MA-induced alterations: decrease in fatty acid-related oxygen consumption rate, OXPHOS capacity, mitochondrial membrane potential (Ψ_mt), and the activity of complex I (CI) as its monomeric and supercomplexes forms; the antioxidant also increased the activity of cytochrome c oxidase as well as mitochondrial biogenesis markers. Thus, SF prevented the MA-induced increase in fission, mitophagy and autophagy markers. In NRK-52E cells, we found that SF prevented the MA-induced cell death, increased mitochondrial mass and ameliorated the loss of Ψ_mt. We concluded that SF-induced biogenesis protects against mitochondrial dysfunction maintaining Ψ_mt, activities of mitochondrial complexes and supercomplexes, and prevents the extensive fission and mitophagy.

Sulforaphane Potentiates Anticancer Effects of Doxorubicin and Cisplatin and Mitigates Their Toxic Effects

The success of cancer therapy is often compromised by the narrow therapeutic index of many anticancer drugs and the occurrence of drug resistance. The association of anticancer therapies with natural compounds is an emerging strategy to improve the pharmaco-toxicological profile of cancer chemotherapy. Sulforaphane, a phytochemical found in cruciferous vegetables, targets multiple pathways involved in cancer development, as recorded in different cancers such as breast, brain, blood, colon, lung, prostate, and so forth. As examples to make the potentialities of the association chemotherapy raise, here we highlight and critically analyze the information available for two associations, each composed by a paradigmatic anticancer drug (cisplatin or doxorubicin) and sulforaphane.

Renoprotective Effects of a New Free Radical Scavenger, XH-003, against Cisplatin-Induced Nephrotoxicity

Acute renal injury has an incidence of 25%–30% in patients with tumors who are treated with cisplatin and in patients for whom no specific drugs are available for treatment. Amifostine is the only FDA-approved chemoprotective drug; however, its clinical application is limited because of side effects. The small-molecule antioxidant XH-003, an acute radiation syndrome- (ARS-) protective drug independently developed in our laboratory, with 100% intellectual property rights, overcomes the side effects of amifostine but retains its high efficacy. In this study, XH-003 showed a chemoprotective effect similar to that of amifostine. A mechanistic study showed that XH-003 could significantly reduce cisplatin-induced increases in serum creatinine and urea nitrogen, increase the activity of antioxidant enzymes (SOD, CAT, and GSH-Px), reduce oxidative stress and tissue inflammation, and alleviate renal tissue damage by blocking the activity of the mitochondrial apoptosis pathway. Most importantly, XH-003 could reduce the accumulation of cisplatin in renal tissue by regulating the expression of proteins involved in cisplatin uptake and excretion, such as organic cation transporter 2 and MRP2. Moreover, in an in vivo xenotransplantation model, XH-003 did not interfere with the antitumor effect of cisplatin. These data provide strong evidence that the ARS-protective agent has a great potential for protecting against chemotherapy-induced toxicity. Thus, XH-003 can be considered in antitumor therapy.

Combinations of the antioxidants sulforaphane or curcumin and the conventional antineoplastics cisplatin or doxorubicin as prospects for anticancer chemotherapy

Drugs used in clinical oncology have narrow therapeutic indices with adverse toxicity often involving oxidative damage. Chemoresistance to these conventional antineoplastics is usually mediated by oxidative stress-upregulated pathways such as those of nuclear factor-kappa B (NF-κB) and hypoxia-inducible factor-1 alpha (HIF-1α). Accordingly, the use of antioxidants in combinational approaches has begun to be considered for fighting cancer because of both the protective role against adverse effects and the ability to sensitize chemoresistant cancer cells. Nuclear factor erythroid 2-related factor 2 (Nrf2) has been identified as a mediator of the cytoprotection but it is not regularly associated with tumor chemosensitization. However, some Nrf2 inducers could be exerting cytoprotective and chemosensitizing roles through a simple integrated mechanism in which the cellular level of reactive oxygen species is controlled, thus inhibiting the oxidative damage in non-target tissues and the tumor chemoresistance mediated by NF-κB or HIF-1α. As examples to show the general idea of this antioxidant combination chemotherapy, this review explores the preclinical information available for four combinations, each composed by a paradigmatic oncological drug (cisplatin or doxorubicin) and a recognized antioxidant (sulforaphane or curcumin). The issues for translating these outcomes to clinical trials are briefly discussed.

Sulforaphane alleviates cadmium-induced toxicity in human mesenchymal stem cells through POR and TNFSF10 genes expression

Sulforaphane is a dietary compound possessing anti-inflammatory, antioxidant, anti-diabetic, anti-carcinogenic, and anti-aging properties. The role of sulforaphane in the context of cadmium (Cd)-induced toxicity through the alteration of nuclear morphology, mitochondrial membrane potential, and gene expression patterns, however, remains unclear. Thus, we assessed the protective role of sulforaphane against Cd-induced nuclear and mitochondrial damage in human mesenchymal stem cells (hMSCs). Cells were exposed to Cd and sulforaphane, either alone or in combination, for 48 h. The cell viability was assessed by adopting MTT assay. The nuclear morphology was investigated using Acridine orange/Ethidium bromide (AO/EB) dual staining and Hoechst staining. The mitochondrial membrane potential loss and lysosomal staining were analyzed using JC-1 staining and LysoRed staining respectively. The gene expression was studied using quantitative real-time PCR analysis. After 48 h of exposure to Cd, the viability of hMSCs decreased in a dose-dependent manner. In contrast, a single treatment with the phytochemical sulforaphane did not cause any remarkable reduction in hMSC viability. Combined treatment with Cd and sulforaphane resulted in a marked recovery in cell viability compared to that observed in cells treated with Cd alone. Analysis of nuclear morphology indicated that Cd induced necrotic cell death, while combined Cd and sulforaphane treatment prevented nuclear morphology changes. Cd ions also significantly attenuate the mitochondrial membrane potential (MMP) and alter gene expression in hMSCs; however, we observed that sulforaphane improves MMP under conditions of Cd-sulforaphane co-treatment of hMSCs. The gene expression results indicate that POR, TNFRSF1A and TNFSF10 genes expression are significantly upregulated by Cd-sulforaphane co-treatment than Cd or sulforaphane treatment alone. Our study results clearly indicate that sulforaphane can protect hMSCs against Cd-induced changes in nuclear morphology, attenuation of MMP, and alteration of gene expression patterns. Thus, intake of sulforaphane-enriched vegetables and fruits will be helpful to overcome Cd-induced toxicity in humans.

Sulforaphane Improves Lipid Metabolism by Enhancing Mitochondrial Function and Biogenesis In Vivo and In Vitro

SCOPE

Sulforaphane (SFN) is reported to reduce the accumulation of lipids. However, the underling mechanism remains unclear. In this study, the potential of SFN to improve lipid metabolism is investigated through altering mitochondrial function and biogenesis-related mechanisms.

METHODS AND RESULTS

The abnormal lipid metabolism model was established both in HHL-5 cells and in rats by feeding a high-fat diet (HFD) for 10 weeks. The current findings suggest that SFN alleviates the swelling of mitochondria and stimulates mitochondrial biogenesis. The reduced expression of NRF1 and TFAM, were reversed by SFN. SFN increases the levels of antioxidant compounds via nuclear factor erythroid-2-related factor (Nrf2) activation. Furthermore, SFN improves multiple mitochondrial bioactivities, such as mitochondrial membrane potential, ATP, and the electron transfer chain based on PGC-1α pathway. SFN also activates lipolysis by transcriptionally upregulating adipose triglyceride lipase (ATGL) and hormone-sensitive lipase (HSL).

CONCLUSIONS

SFN enhances utilization of lipids via both the PGC- 1α-dependent promotion of mitochondrial biogenesis and Nrf2 dependent improvement of mitochondrial function.

Preventing childhood and lifelong disability: Maternal dietary supplementation for perinatal brain injury

The majority of brain injuries that lead to cerebral palsy, developmental disability, and mental health disorders have their onset in utero. These lifelong conditions come with great economic and emotional burden as they impact function in nearly all domains of affected individuals' lives. Unfortunately, current therapeutic options are limited. There remains a focus on rescue, rehabilitation, and regeneration after the injury has occurred, rather than aiming to prevent the initial injury. Prevention would imply treating the mother during pregnancy to alter the fetal environment and in turn, treat the fetus. Fear of harming the developing fetus remains as a result of errors of the past such as the release of thalidomide. In this review, we outline evidence from animal studies and clinical trials that have explored maternal dietary supplementation with natural health products (including nutraceuticals and functional foods) for perinatal brain injury prevention. Namely, we discuss magnesium sulphate, creatine, choline, melatonin, resveratrol and broccoli sprouts/sulforaphane. Although clinical trials have only been completed in this realm for magnesium sulphate, results in animal models have been promising, suggesting that this is a productive avenue for further research. Natural health products may provide safe, effective, affordable, and easily accessible prevention of fetal brain injury and resulting lifelong disabilities.

Phenethyl isothiocyanate protects against H2O2-induced insulin resistance in 3T3-L1 adipocytes

Obesity is associated with systemic oxidative stress and leads to insulin resistance. Phenethyl isothiocyanate (PEITC), a natural dietary isothiocyanate, has been shown to have beneficial effects in improving cellular defense activities against oxidative stress through activation of nuclear factor erythroid-2 related factor 2 (Nrf2) pathway. However, little evidence exists if the antioxidative activity has beneficial effects on glucose metabolism. Here, we tested the preventive potential of PEITC for impaired insulin-induced glucose uptake by oxidative stress in 3T3-L1 adipocytes. Treatment with PEITC increased the expression of antioxidative enzymes regulated by Nrf2 such as γ-glutamylcysteine-synthetase, heme oxygenase 1, NAD(P)H:quinone oxidoreductase 1 and glutathione S-transferase, and reduced oxidative stress induced by H₂O₂. Furthermore, PEITC restored impaired insulin-stimulated glucose uptake, translocation of glucose transporter 4 and insulin signaling by H₂O₂. These results indicate that PEITC protected insulin-regulated glucose metabolism impaired by oxidative stress through the antioxidative activity in 3T3-L1 adipocytes.

In vitro assessment of the indirect antioxidant activity of Sulforaphane in redox imbalance vanadium-induced

Owing to sulforaphane presence, a dietary consumption of Brassicaceae prevents chronic diseases. This hormetic compound induces adaptive stress response at subtoxic doses, while doses that exceed the cellular defence are toxic. In HepG2, Caco-2 and Vero cells, we investigated the sulforaphane (SFN) (5 μM) role in counteracting redox imbalance induced by VOSO₄ [V(IV)]. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) test showed a dose-dependent viability reduction (r < -0.95; p < 0.01) (range 5-80 μM). At 5 μM, SFN enhancement of mitochondrial activity was confirmed by Δψm (p < 0.05) both in basal condition and in redox-stressed cells. Intracellular ROS, DNA and lysosomal oxidative damages underlined the indirect antioxidant SFN activity, confirmed by the increase of GSH. The SFN empowering effects on mitochondrial function were imputable to the presence of mitochondrial proteins among the Nrf2-responsive phase II proteins. Considering the link between oxidative stress and chronic diseases, a long-term dietary intake of Brassicaceae could be strongly advisable.

Sulforaphane induces differential modulation of mitochondrial biogenesis and dynamics in normal cells and tumor cells

Antioxidant-based chemotherapy has been intensely debated. Herein, we show that sulforaphane (SFN) induced mitochondrial biogenesis followed by mitochondrial fusion in a kidney cell line commonly used in nephroprotective models. At the same concentration and exposure time, SFN induced cell death in prostate cancer cells accompanied by mitochondrial biogenesis and fragmentation. Stabilization of the nuclear factor E2-related factor-2 (Nrf2) could be associated with these effects in the tumor cell line. An increase in the peroxisome proliferator-activated receptor-γ co-activator-1α (PGC1α) level and a decrease in the hypoxia-inducible factor-1α (HIF1α) level would suggest a possible metabolic shift. The knockdown in the nuclear respiratory factor-1 (NRF1) attenuated the SFN-induced effect on prostate cancer cells demonstrating that mitochondrial biogenesis plays an important role in cell death for this kind of tumor cells. This evidence supports SFN as a potential antineoplastic agent that could inhibit tumor development and could protect normal tissues by modulating common processes.

Sulforaphane prevents quinolinic acid-induced mitochondrial dysfunction in rat striatum

Quinolinic acid (QA) triggers striatal neuronal death by an excitotoxic cascade that involves oxidative stress, which in turns is tightly linked to mitochondria. Mitochondrial dysfunction is a molecular feature described in several brain pathologies. In this work, we determined whether the sulforaphane-neuroprotective effect in the rodent experimental model of Huntington's disease induced by QA is associated with mitochondrial function preservation. We found that QA impaired mitochondrial function within 24 h post-lesion. Sulforaphane effectively disrupted the mitochondrial dysfunction by preventing the decrease in respiratory control ratio, transmembrane potential, ability to synthetize ATP, and the activity of mitochondrial complexes I, II, and IV.

The emerging role of Nrf2 in mitochondrial function

The transcription factor NF-E2 p45-related factor 2 (Nrf2; gene name NFE2L2) allows adaptation and survival under conditions of stress by regulating the gene expression of diverse networks of cytoprotective proteins, including antioxidant, anti-inflammatory, and detoxification enzymes as well as proteins that assist in the repair or removal of damaged macromolecules. Nrf2 has a crucial role in the maintenance of cellular redox homeostasis by regulating the biosynthesis, utilization, and regeneration of glutathione, thioredoxin, and NADPH and by controlling the production of reactive oxygen species by mitochondria and NADPH oxidase. Under homeostatic conditions, Nrf2 affects the mitochondrial membrane potential, fatty acid oxidation, availability of substrates (NADH and FADH2/succinate) for respiration, and ATP synthesis. Under conditions of stress or growth factor stimulation, activation of Nrf2 counteracts the increased reactive oxygen species production in mitochondria via transcriptional upregulation of uncoupling protein 3 and influences mitochondrial biogenesis by maintaining the levels of nuclear respiratory factor 1 and peroxisome proliferator-activated receptor γ coactivator 1α, as well as by promoting purine nucleotide biosynthesis. Pharmacological Nrf2 activators, such as the naturally occurring isothiocyanate sulforaphane, inhibit oxidant-mediated opening of the mitochondrial permeability transition pore and mitochondrial swelling. Curiously, a synthetic 1,4-diphenyl-1,2,3-triazole compound, originally designed as an Nrf2 activator, was found to promote mitophagy, thereby contributing to the overall mitochondrial homeostasis. Thus, Nrf2 is a prominent player in supporting the structural and functional integrity of the mitochondria, and this role is particularly crucial under conditions of stress.

Curcumin Attenuates Gentamicin-Induced Kidney Mitochondrial Alterations: Possible Role of a Mitochondrial Biogenesis Mechanism

It has been shown that curcumin (CUR), a polyphenol derived from Curcuma longa, exerts a protective effect against gentamicin- (GM-) induced nephrotoxicity in rats, associated with a preservation of the antioxidant status. Although mitochondrial dysfunction is a hallmark in the GM-induced renal injury, the role of CUR in mitochondrial protection has not been studied. In this work, LLC-PK1 cells were preincubated 24 h with CUR and then coincubated 48 h with CUR and 8 mM GM. Treatment with CUR attenuated GM-induced drop in cell viability and led to an increase in nuclear factor (erythroid-2)-related factor 2 (Nrf2) nuclear accumulation and peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α) cell expression attenuating GM-induced losses in these proteins. In vivo, Wistar rats were injected subcutaneously with GM (75 mg/Kg/12 h) during 7 days to develop kidney mitochondrial alterations. CUR (400 mg/Kg/day) was administered orally 5 days before and during the GM exposure. The GM-induced mitochondrial alterations in ultrastructure and bioenergetics as well as decrease in activities of respiratory complexes I and IV and induction of calcium-dependent permeability transition were mostly attenuated by CUR. Protection of CUR against GM-induced nephrotoxicity could be in part mediated by maintenance of mitochondrial functions and biogenesis with some participation of the nuclear factor Nrf2.

C-phycocyanin prevents cisplatin-induced mitochondrial dysfunction and oxidative stress

The potential of C-phycocyanin (C-PC) to prevent cisplatin (CP)-induced kidney mitochondrial dysfunction was determined in CD-1 male mice. The CP-induced mitochondrial dysfunction was characterized by ultrastructural abnormalities and by decrease in the following parameters in isolated kidney mitochondria: adenosine diphosphate (ADP)-induced oxygen consumption (state 3), respiratory control ratio, ADP/oxygen (ADP/O) ratio, adenosine triphosphate synthesis, membrane potential, calcium retention, glutathione (GSH) content, and activity of respiratory complex I, aconitase, catalase, and GSH peroxidase. These mitochondria also showed increase in hydrogen peroxide production, malondialdehyde, and 3-nitrotyrosine protein adducts content. The above-described changes, as well as CP-induced nephrotoxicity, were attenuated in mice pretreated with a single injection of C-PC. Our data suggest that the attenuation of mitochondrial abnormalities is involved in the protective effect of C-PC against CP-induced nephrotoxicity. This is the first demonstration that C-PC pretreatment prevents CP-induced mitochondrial dysfunction in mice.

Mitochondrial modulation by Epigallocatechin 3-Gallate ameliorates cisplatin induced renal injury through decreasing oxidative/nitrative stress, inflammation and NF-kB in mice

Cancer chemotherapy drug cisplatin is known for its nephrotoxicity. The aim of this study is to investigate whether Epigallocatechin 3-Gallate (EGCG) can reduce cisplatin mediated side effect in kidney and to understand its mechanism of protection against tissue injury. We used a well-established 3-day cisplatin induced nephrotoxicity mice model where EGCG were administered. EGCG is a major active compound in Green Tea and have strong anti-oxidant and anti-inflammatory properties. EGCG protected against cisplatin induced renal dysfunction as measured by serum creatinine and blood urea nitrogen (BUN). EGCG improved cisplatin induced kidney structural damages such as tubular dilatation, cast formation, granulovaculoar degeneration and tubular cell necrosis as evident by PAS staining. Cisplatin induced kidney specific mitochondrial oxidative stress, impaired activities of mitochondrial electron transport chain enzyme complexes, impaired anti-oxidant defense enzyme activities such as glutathione peroxidase (GPX) and manganese superoxide dismutase (MnSOD) in mitochondria, inflammation (tumor necrosis factor α and interleukin 1β), increased accumulation of NF-κB in nuclear fraction, p53 induction, and apoptotic cell death (caspase 3 activity and DNA fragmentation). Treatment of mice with EGCG markedly attenuated cisplatin induced mitochondrial oxidative/nitrative stress, mitochondrial damages to electron transport chain activities and antioxidant defense enzyme activities in mitochondria. These mitochondrial modulations by EGCG led to protection mechanism against cisplatin induced inflammation and apoptotic cell death in mice kidney. As a result, EGCG improved renal function in cisplatin mediated kidney damage. In addition to that, EGCG attenuated cisplatin induced apoptotic cell death and mitochondrial reactive oxygen species (ROS) generation in human kidney tubular cell line HK-2. Thus, our data suggest that EGCG may represent new promising adjunct candidate for cisplatin.

Pharmacological targeting of GSK3β confers protection against podocytopathy and proteinuria by desensitizing mitochondrial permeability transition

BACKGROUND AND PURPOSE

Mitochondrial dysfunction, triggered by mitochondria permeability transition (MPT), has been centrally implicated in the pathogenesis of podocytopathy and involves a multitude of cell signalling mechanisms, among which, glycogen synthase kinase (GSK) 3β has emerged as the integration point and plays a crucial role. This study aimed to examine the role of GSK3β in podocyte MPT and mitochondrial dysfunction.

EXPERIMENTAL APPROACH

The regulatory effect of GSK3β on MPT was examined in differentiated podocytes in culture and in a murine model of adriamycin-induced podocytopathy using 4-benzyl-2-methyl-1,2,4-thiadiazolidine-3,5-dione (TDZD-8), a highly selective small-molecule inhibitor of GSK3β.

KEY RESULTS

TDZD-8 therapy prominently ameliorated the proteinuria and glomerular sclerosis in mice with adriamycin nephropathy; this was associated with a correction of GSK3β overactivity in the glomerulus and attenuation of podocyte injuries, including foot process effacement and podocyte death. Consistently, in adriamycin-injured podocytes, TDZD-8 treatment counteracted GSK3β overactivity, improved cell viability and prevented death, concomitant with diminished oxidative stress, improved mitochondrial dysfunction and desensitized MPT. Mechanistically, a discrete pool of GSK3β was found in podocyte mitochondria, which interacted with and phosphorylated clyclophilin F, a key structural component of the MPT pore. TDZD-8 treatment prevented the GSK3β-controlled phosphorylation and activation of cyclophilin F, desensitized MPT and alleviated the damage to mitochondria in podocytes induced by adriamycin in vivo and in vitro.

CONCLUSIONS AND IMPLICATIONS

Our findings suggest that pharmacological targeting of GSK3β could represent a promising and feasible therapeutic strategy for protecting podocytes against mitochondrial dysfunction induced by oxidative injuries.

Protective effects of methanolic extract form fruits of Lycium ruthenicum Murr on 2,2'-azobis (2-amidinopropane) dihydrochloride-induced oxidative stress in LLC-PK1 cells

Background:

Fruits of Lycium ruthenicum Murr is a health food and also used as a folk to treat heart disease, abnormal menstruation and menopause in Tibetan, China. However; whether L. ruthenicum Murr fruits methanolic extracts (LFME) protect LLC-PK1 porcine renal tubules cells from AAPH-induced oxidative damage has not been investigated.

Objective:

To investigate the protective effects of L. ruthenicum Murr fruits methanolic extracts (LFME) against 2, 2’- azobis (2-amidinopropane) dihydrochloride (AAPH)-induced oxidative damage in renal proximal tubule LLC-PK1 cells.

Materials and Methods:

LLC-PK1 cells were co-incubated with AAPH (1mM) and different concentrations of LFMW together for 24 h. Cell viability was determined by MTT assay. Total intercellular reactive oxygen species (ROS) levels and lipid peroxidation were measured using a fluorescent probe 2’, 7’-dichlorfluorescein-diacetate (DCFH-DA) and the TBA reactive substance (TBARS) assay, respectively. The endogenous antioxidant enzymes including catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GSH-px) and intercellular glutathione (GSH) levels were determined using commercial assay kits according to the manufacturer's instructions.

Results:

LFME did not show a significant cytotoxic effect and increased the viability of LLC-PK1 cells in a concentration-dependent manner. LFME also decreased the total intercellular levels of ROS, reduced lipid peroxidation and increased the GSH levels as well as the activities of endogenous antioxidant enzymes to protect LLC-PK1 cells against AAPH-induced oxidative damage.

Conclusion:

The results from the present study indicated that LFME is an effective ROS scavenger to protect LLC-PK1 cells against AAPH-induced oxidative damage through decreasing ROS generation, reducing lipid peroxidation and up-regulation of endogenous GSH levels and antioxidant enzymes.

Curcumin prevents maleate-induced nephrotoxicity: relation to hemodynamic alterations, oxidative stress, mitochondrial oxygen consumption and activity of respiratory complex I

The potential protective effect of the dietary antioxidant curcumin (120 mg/Kg/day for 6 days) against the renal injury induced by maleate was evaluated. Tubular proteinuria and oxidative stress were induced by a single injection of maleate (400 mg/kg) in rats. Maleate-induced renal injury included increase in renal vascular resistance and in the urinary excretion of total protein, glucose, sodium, neutrophil gelatinase-associated lipocalin (NGAL) and N-acetyl β-D-glucosaminidase (NAG), upregulation of kidney injury molecule (KIM)-1, decrease in renal blood flow and claudin-2 expression besides of necrosis and apoptosis of tubular cells on 24 h. Oxidative stress was determined by measuring the oxidation of lipids and proteins and diminution in renal Nrf2 levels. Studies were also conducted in renal epithelial LLC-PK1 cells and in mitochondria isolated from kidneys of all the experimental groups. Maleate induced cell damage and reactive oxygen species (ROS) production in LLC-PK1 cells in culture. In addition, maleate treatment reduced oxygen consumption in ADP-stimulated mitochondria and diminished respiratory control index when using malate/glutamate as substrate. The activities of both complex I and aconitase were also diminished. All the above-described alterations were prevented by curcumin. It is concluded that curcumin is able to attenuate in vivo maleate-induced nephropathy and in vitro cell damage. The in vivo protection was associated to the prevention of oxidative stress and preservation of mitochondrial oxygen consumption and activity of respiratory complex I, and the in vitro protection was associated to the prevention of ROS production.

Effect of redox modulating NRF2 activators on chronic kidney disease

Chronic kidney disease (CKD) is featured by a progressive decline of kidney function and is mainly caused by chronic diseases such as diabetes mellitus and hypertension. CKD is a complex disease due to cardiovascular complications and high morbidity; however, there is no single treatment to improve kidney function in CKD patients. Since biological markers representing oxidative stress are significantly elevated in CKD patients, oxidative stress is receiving attention as a contributing factor to CKD pathology. Nuclear factor erythroid-2 related factor 2 (NRF2) is a predominant transcription factor that regulates the expression of a wide array of genes encoding antioxidant proteins, thiol molecules and their generating enzymes, detoxifying enzymes, and stress response proteins, all of which can counteract inflammatory and oxidative damages. There is considerable experimental evidence suggesting that NRF2 signaling plays a protective role in renal injuries that are caused by various pathologic conditions. In addition, impaired NRF2 activity and consequent target gene repression have been observed in CKD animals. Therefore, a pharmacological intervention activating NRF2 signaling can be beneficial in protecting against kidney dysfunction in CKD. This review article provides an overview of the role of NRF2 in experimental CKD models and describes current findings on the renoprotective effects of naturally occurring NRF2 activators, including sulforaphane, resveratrol, curcumin, and cinnamic aldehyde. These experimental results, coupled with recent clinical experiences with a synthetic triterpenoid, bardoxolone methyl, have brought a light of hope for ameliorating CKD progression by preventing oxidative stress and maintaining cellular redox homeostasis.

Sulforaphane reduces the alterations induced by quinolinic acid: modulation of glutathione levels

Glutamate-induced excitotoxicity involves a state of acute oxidative stress, which is a crucial event during neuronal degeneration and is part of the physiopathology of neurodegenerative diseases. In this work, we evaluated the ability of sulforaphane (SULF), a natural dietary isothiocyanate, to induce the activation of transcription factor Nrf2 (a master regulator of redox state in the cell) in a model of striatal degeneration in rats infused with quinolinic acid (QUIN). Male Wistar rats received SULF (5mg/kg, i.p.) 24h and 5min before the intrastriatal infusion of QUIN. SULF increased the reduced glutathione (GSH) levels 4h after QUIN infusion, which was associated with its ability to increase the activity of glutathione reductase (GR), an antioxidant enzyme capable to regenerate GSH levels at 24h. Moreover, SULF treatment increased glutathione peroxidase (GPx) activity, while no changes were observed in γ-glutamyl cysteine ligase (GCL) activity. SULF treatment also prevented QUIN-induced oxidative stress (measured by oxidized proteins levels), the histological damage and the circling behavior. These results suggest that the protective effect of SULF could be related to its ability to preserve GSH levels and increase GPx and GR activities.

Canonical and new generation anticancer drugs also target energy metabolism

Significant efforts have been made for the development of new anticancer drugs (protein kinase or proteasome inhibitors, monoclonal humanized antibodies) with presumably low or negligible side effects and high specificity. However, an in-depth analysis of the side effects of several currently used canonical (platin-based drugs, taxanes, anthracyclines, etoposides, antimetabolites) and new generation anticancer drugs as the first line of clinical treatment reveals significant perturbation of glycolysis and oxidative phosphorylation. Canonical and new generation drug side effects include decreased (1) intracellular ATP levels, (2) glycolytic/mitochondrial enzyme/transporter activities and/or (3) mitochondrial electrical membrane potentials. Furthermore, the anti-proliferative effects of these drugs are markedly attenuated in tumor rho (0) cells, in which functional mitochondria are absent; in addition, several anticancer drugs directly interact with isolated mitochondria affecting their functions. Therefore, several anticancer drugs also target the energy metabolism, and hence, the documented inhibitory effect of anticancer drugs on cancer growth should also be linked to the blocking of ATP supply pathways. These often overlooked effects of canonical and new generation anticancer drugs emphasize the role of energy metabolism in maintaining cancer cells viable and its targeting as a complementary and successful strategy for cancer treatment.

The Nrf2 regulatory network provides an interface between redox and intermediary metabolism

Nuclear factor-erythroid 2 p45-related factor 2 (Nrf2, also called Nfe2l2) is a transcription factor that regulates the cellular redox status. Nrf2 is controlled through a complex transcriptional/epigenetic and post-translational network that ensures its activity increases during redox perturbation, inflammation, growth factor stimulation and nutrient/energy fluxes, thereby enabling the factor to orchestrate adaptive responses to diverse forms of stress. Besides mediating stress-stimulated induction of antioxidant and detoxification genes, Nrf2 contributes to adaptation by upregulating the repair and degradation of damaged macromolecules, and by modulating intermediary metabolism. In the latter case, Nrf2 inhibits lipogenesis, supports β-oxidation of fatty acids, facilitates flux through the pentose phosphate pathway, and increases NADPH regeneration and purine biosynthesis; these observations suggest Nrf2 directs metabolic reprogramming during stress.

Modulation of mitochondrial functions by the indirect antioxidant sulforaphane: a seemingly contradictory dual role and an integrative hypothesis

The chemotherapeutic isothiocyanate sulforaphane (SFN) was early linked to anticarcinogenic and antiproliferative activities. Soon after, this compound, derived from cruciferous vegetables, became an excellent and useful trial for anti-cancer research in experimental models including growth tumor, metastasis, and angiogenesis. Many subsequent reports showed modifications in mitochondrial signaling, functionality, and integrity induced by SFN. When cytoprotective effects were found in toxic and ischemic insult models, seemingly contradictory behaviors of SFN were discovered: SFN was inducing deleterious changes in cancer cell mitochondria that eventually would carry the cell to death via apoptosis and also was protecting noncancer cell mitochondria against oxidative challenge, which prevented cell death. In both cases, SFN exhibited effects on mitochondrial redox balance and phase II enzyme expression, mitochondrial membrane potential, expression of the family of B cell lymphoma 2 homologs, regulation of proapoptotic proteins released from mitochondria, activation/inactivation of caspases, mitochondrial respiratory complex activities, oxygen consumption and bioenergetics, mitochondrial permeability transition pore opening, and modulation of some kinase pathways. With the ultimate findings related to the induction of mitochondrial biogenesis by SFN, it could be considered that SFN has effects on mitochondrial dynamics that explain some divergent points. In this review, we list the reports involving effects on mitochondrial modulation by SFN in anti-cancer models as well as in cytoprotective models against oxidative damage. We also attempt to integrate the data into a mechanism explaining the various effects of SFN on mitochondrial function in only one concept, taking into account mitochondrial biogenesis and dynamics and making a comparison with the theory of reactive oxygen species threshold of cell death. Our interest is to achieve a complete view of cancer and protective therapies based on SFN that can be extended to other chemotherapeutic compounds with similar characteristics. The work needed to test this hypothesis is quite extensive.

Redox-sensitive glycogen synthase kinase 3β-directed control of mitochondrial permeability transition: rheostatic regulation of acute kidney injury

Mitochondrial dysfunction plays a pivotal role in necroapoptotic cell death and in the development of acute kidney injury (AKI). Evidence suggests that glycogen synthase kinase (GSK) 3β resides at the nexus of multiple signaling pathways implicated in the regulation of mitochondrial permeability transition (MPT). In cultured renal tubular epithelial cells, a discrete pool of GSK3β was detected in mitochondria. Coimmunoprecipitation assay confirmed that GSK3β physically interacts with cyclophilin F and voltage-dependent anion channel (VDAC), key MPT regulators that possess multiple GSK3β phosphorylation consensus motifs, suggesting that GSK3β has a direct control of MPT. Upon a strong burst of reactive oxygen species elicited by the pro-oxidant herbicide paraquat, the activity of the redox-sensitive GSK3β was drastically enhanced. This was accompanied by augmented phosphorylation of cyclophilin F and VDAC, associated with MPT and cell death. Inhibition of GSK3β by either the selective inhibitor 4-Benzyl-2-methyl-1,2,4-thiadiazolidine-3,5-dione (TDZD-8) or forced expression of a kinase-dead mutant obliterated paraquat-induced phosphorylation of cyclophilin F and VDAC, prevented MPT, and improved cellular viability. Conversely, ectopic expression of a constitutively active GSK3β amplified the effect of paraquat on cyclophilin F and VDAC phosphorylation and sensitized cells to paraquat-induced MPT and death. In vivo, paraquat injection elicited marked oxidant stress in the kidney and resulted in acute kidney dysfunction and massive tubular apoptosis and necrosis. Consistent with in vitro findings, the activity of GSK3β was augmented in the kidney after paraquat injury, associated with increased phosphorylation of cyclophilin F and VDAC and sensitized MPT. TDZD-8 blocked GSK3β activity in the kidney, intercepted cyclophilin F and VDAC phosphorylation, prevented MPT, attenuated tubular cell death, and ameliorated paraquat-induced AKI. Our data suggest that the redox-sensitive GSK3β regulates renal tubular injury in AKI by controlling the activity of MPT regulators.

Curcumin maintains cardiac and mitochondrial function in chronic kidney disease

Curcumin, a natural pigment with antioxidant activity obtained from turmeric and largely used in traditional medicine, is currently being studied in the chemoprevention of several diseases for its pleiotropic effects and nontoxicity. In chronic renal failure, the pathogenic mechanisms leading to cardiovascular disorders have been associated with increased oxidative stress, a process inevitably linked with mitochondrial dysfunction. Thus, in this study we aimed at investigating if curcumin pretreatment exerts cardioprotective effects in a rat model of subtotal nephrectomy (5/6Nx) and its impact on mitochondrial homeostasis. Curcumin was orally administered (120mg/kg) to Wistar rats 7 days before nephrectomy and after surgery for 60 days (5/6Nx+curc). Renal dysfunction was detected a few days after nephrectomy, whereas changes in cardiac function were observed until the end of the protocol. Our results indicate that curcumin treatment protects against pathological remodeling, diminishes ischemic events, and preserves cardiac function in uremic rats. Cardioprotection was related to diminished reactive oxygen species production, decreased oxidative stress markers, increased antioxidant response, and diminution of active metalloproteinase-2. We also observed that curcumin's cardioprotective effects were related to maintaining mitochondrial function. Aconitase activity was significantly higher in the 5/6Nx + curc (408.5±68.7nmol/min/mg protein) than in the 5/6Nx group (104.4±52.3nmol/min/mg protein, P<0.05), and mitochondria from curcumin-treated rats showed enhanced oxidative phosphorylation capacities with both NADH-linked substrates and succinate plus rotenone (3.6±1 vs 1.1±0.9 and 3.1±0.7 vs 1.2±0.8, respectively, P<0.05). The mechanisms involved in cardioprotection included both direct antioxidant effects and indirect strategies that could be related to protein kinase C-activated downstream signaling.

Sulforaphane attenuates gentamicin-induced nephrotoxicity: role of mitochondrial protection

Sulforaphane (SFN), an isothiocyanate naturally occurring in Cruciferae, induces cytoprotection in several tissues. Its protective effect has been associated with its ability to induce cytoprotective enzymes through an Nrf2-dependent pathway. Gentamicin (GM) is a widely used antibiotic; nephrotoxicity is the main side effect of this compound. In this study, it was investigated if SFN is able to induce protection against GM-induced nephropathy both in renal epithelial LLC-PK1 cells in culture and in rats. SFN prevented GM-induced death and loss of mitochondrial membrane potential in LLC-PK1 cells. In addition, it attenuated GM-induced renal injury (proteinuria, increases in serum creatinine, in blood urea nitrogen, and in urinary excretion on N-acetyl-β-D-glucosaminidase, and decrease in creatinine clearance and in plasma glutathione peroxidase activity) and necrosis and apoptosis in rats. The apoptotic death was associated with enhanced active caspase-9. Caspase-8 was unchanged in all the studied groups. In addition, SFN was able to prevent GM-induced protein nitration and decrease in the activity of antioxidant enzymes catalase and glutathione peroxidase in renal cortex. In conclusion, the protective effect of SFN against GM-induced acute kidney injury could be associated with the preservation in mitochondrial function that would prevent the intrinsic apoptosis and nitrosative stress.

Nrf2 signalling promotes ex vivo tubular epithelial cell survival and regeneration via murine double minute (MDM)-2

BACKGROUND

Tubular repair upon injury involves regeneration from either surviving tubular epithelial cells or from their surviving local progenitor cells; hence, compound screening with cell lines may be inadequate. Here, we demonstrate that the renal cell isolation procedure and subsequent outgrowth of tubular cells can mimic the renal injury phase and tubular cell regeneration from whichever surviving renal cells.

METHODS

We set up assays to systematically screen and identify mediators of tubular survival and repair.

RESULTS

Forty-eight hours after plating total kidney isolates from C57BL/6 mice, 69% of cells survived when prepared from 2-week-old pups, but only 4% of cells from 8-week-old mice, respectively. This poor survival was not modulated by co-incubation with any of 24 cytokines and growth factors, except for the Nrf2 agonist sulforaphane. In addition, only sulforaphane enhanced the regenerative outgrowth of tubular epithelial cells from the mixed population. Furthermore, sulforaphane enhanced wound closure upon scratching tubular epithelial cell monolayers in a dose-dependent manner. This process was associated with the induction of the tested Nrf2 target genes HO-1, NQO1 and murine-double minute 2 (MDM2). MDM2 blockade with nutlin-3a completely blocked the protective effects of sulforaphane on renal cell survival, outgrowth and wound closure.

CONCLUSIONS

Together, renal cell isolation is a model of acute kidney injury (AKI). Primary tubular epithelial cell outgrowth represents a model of tubular regeneration. Nrf2 activation can enhance renal cell survival and tubular repair by inducing the cell cycle regulator MDM2.

Curcumin induces Nrf2 nuclear translocation and prevents glomerular hypertension, hyperfiltration, oxidant stress, and the decrease in antioxidant enzymes in 5/6 nephrectomized rats

Renal injury resulting from renal ablation induced by 5/6 nephrectomy (5/6NX) is associated with oxidant stress, glomerular hypertension, hyperfiltration, and impaired Nrf2-Keap1 pathway. The purpose of this work was to know if the bifunctional antioxidant curcumin may induce nuclear translocation of Nrf2 and prevents 5/6NX-induced oxidant stress, renal injury, decrease in antioxidant enzymes, and glomerular hypertension and hyperfiltration. Four groups of rats were studied: (1) control, (2) 5/6NX, (3) 5/6NX +CUR, and (4) CUR (n = 8–10). Curcumin was given by gavage to NX5/6 +CUR and CUR groups (60 mg/kg/day) starting seven days before surgery. Rats were studied 30 days after NX5/6 or sham surgery. Curcumin attenuated 5/6NX-induced proteinuria, systemic and glomerular hypertension, hyperfiltration, glomerular sclerosis, interstitial fibrosis, interstitial inflammation, and increase in plasma creatinine and blood urea nitrogen. This protective effect was associated with enhanced nuclear translocation of Nrf2 and with prevention of 5/6NX-induced oxidant stress and decrease in the activity of antioxidant enzymes. It is concluded that the protective effect of curcumin against 5/6NX-induced glomerular and systemic hypertension, hyperfiltration, renal dysfunction, and renal injury was associated with the nuclear translocation of Nrf2 and the prevention of both oxidant stress and the decrease of antioxidant enzymes.

Protective effect of sulforaphane pretreatment against cisplatin-induced liver and mitochondrial oxidant damage in rats

In the present work was analyzed whether sulforaphane (SFN) may protect against cisplatin (CIS)-induced hepatic damage, oxidant stress and mitochondrial dysfunction. Four groups of male Wistar rats were studied: control, CIS, CIS+SFN and SFN. SFN was given i.p. (500 μg/kg/d × 3 days) before CIS administration (single i.p. injection, 10mg/kg). Rats were sacrificed 3 days after CIS injection to evaluate hepatic damage (histological analysis, liver/body weight ratio and serum activity of aspartate aminotransferase and alanine aminotransferase), oxidant stress (lipid peroxidation and protein carbonyl and glutathione content), antioxidant enzymes (catalase, glutathione reductase, glutathione peroxidase, glutathione-S-transferase and superoxide dismutase) in liver homogenates and isolated mitochondria and mitochondrial function (oxygen consumption using either malate/glutamate or succinate as substrates and the activity of mitochondrial complex I, II, II-III, IV and V). Furthermore it was evaluated if SFN is able to scavenge some reactive oxygen species in vitro. It was found that SFN prevents CIS-induced (a) hepatic damage, (b) oxidant stress and decreased activity of antioxidant enzymes in liver and mitochondria and (c) mitochondrial alterations in oxygen consumption and decreased activity of mitochondrial complex I. It was also found that the scavenging ability of SFN for peroxynitrite anion, superoxide anion, singlet oxygen, peroxyl radicals, hydrogen peroxide and hydroxyl radicals was very low or negligible. The hepatoprotective effect of SFN was associated to the preservation of mitochondrial function, antioxidant enzymes and prevention of liver and mitochondrial oxidant stress.

Protective effect of sulforaphane against oxidative stress: recent advances

Sulforaphane [1-isothiocyanate-(4R)-(methylsulfinyl)butane] is a natural dietary isothiocyanate produced by the enzymatic action of the myrosinase on glucopharanin, a 4-methylsulfinylbutyl glucosinolate contained in cruciferous vegetables of the genus Brassica such as broccoli, brussel sprouts, and cabbage. Studies on this compound is increasing because its anticarcinogenic and cytoprotective properties in several in vivo experimental paradigms associated with oxidative stress such as focal cerebral ischemia, brain inflammation, intracerebral hemorrhage, ischemia and reperfusion induced acute renal failure, cisplatin induced-nephrotoxicity, streptozotocin-induced diabetes, carbon tetrachloride-induced hepatotoxicity and cardiac ischemia and reperfusion. This protective effect also has been observed in in vitro studies in different cell lines such as human neuroblastoma SH-SY5Y, renal epithelial proximal tubule LLC-PK1 cells and aortic smooth muscle A10 cells. Sulforaphane is considered an indirect antioxidant; this compound is able to induce many cytoprotective proteins, including antioxidant enzymes, through the Nrf2-antioxidant response element pathway. Heme oxygenase-1, NAD(P)H: quinone oxidoreductase, glutathione-S-transferase, gamma-glutamyl cysteine ligase, and glutathione reductase are among the cytoprotective proteins induced by sulforaphane. In conclusion, sulforaphane is a promising antioxidant agent that is effective to attenuate oxidative stress and tissue/cell damage in different in vivo and in vitro experimental paradigms.