Iron- and ascorbic acid-induced lipid peroxidation in renal microsomes isolated from rats treated with platinum compounds

Regression Modeling of the Antioxidant-to-Nephroprotective Relation Shows the Pivotal Role of Oxidative Stress in Cisplatin Nephrotoxicity

The clinical utility of the chemotherapeutic drug cisplatin is significantly limited by its nephrotoxicity, which is characterized by electrolytic disorders, glomerular filtration rate decline, and azotemia. These alterations are consequences of a primary tubulopathy causing injury to proximal and distal epithelial cells, and thus tubular dysfunction. Oxidative stress plays a role in cisplatin nephrotoxicity and cytotoxicity, but its relative contribution to overall toxicity remains unknown. We studied the relation between the degree of oxidative reduction (provided by antioxidant treatment) and the extent of nephrotoxicity amelioration (i.e., nephroprotection) by means of a regression analysis of studies in animal models. Our results indicate that a linear relation exists between these two parameters, and that this relation very nearly crosses the value of maximal nephroprotection at maximal antioxidant effect, suggesting that oxidative stress seems to be a pivotal and mandatory mechanism of cisplatin nephrotoxicity, and, hence, an interesting, rationale-based target for clinical use. Our model also serves to identify antioxidants with enhanced effectiveness by comparing their actual nephroprotective power with that predicted by their antioxidant effect. Among those, this study identified nanoceria, erythropoietin, and maltol as highly effective candidates affording more nephroprotection than expected from their antioxidant effect for prospective clinical development.

Regulated cell death in cisplatin-induced AKI: relevance of myo-inositol metabolism

Regulated cell death (RCD), distinct from accidental cell death, refers to a process of well-controlled programmed cell death with well-defined pathological mechanisms. In the past few decades, various terms for RCDs were coined, and some of them have been implicated in the pathogenesis of various types of acute kidney injury (AKI). Cisplatin is widely used as a chemotherapeutic drug for a broad spectrum of cancers, but its usage was hampered because of being highly nephrotoxic. Cisplatin-induced AKI is commonly seen clinically, and it also serves as a well-established prototypic model for laboratory investigations relevant to acute nephropathy affecting especially the tubular compartment. Literature reports over a period of three decades have indicated that there are multiple types of RCDs, including apoptosis, necroptosis, pyroptosis, ferroptosis, and mitochondrial permeability transition-mediated necrosis, and some of them are pertinent to the pathogenesis of cisplatin-induced AKI. Interestingly, myo-inositol metabolism, a vital biological process that is largely restricted to the kidney, seems to be relevant to the pathogenesis of certain forms of RCDs. A comprehensive understanding of RCDs in cisplatin-induced AKI and their relevance to myo-inositol homeostasis may yield novel therapeutic targets for the amelioration of cisplatin-related nephropathy.

Protective Effect of DPPD on Mercury Chloride-Induced Hepatorenal Toxicity in Rats

Mercury is a global environmental pollutant, accumulating mainly in the kidney and liver inducing hepatorenal toxicity, oxidative stress, and tissue damage. Oxidative stress is caused by an imbalance between free radicals' production and cellular antioxidant defense systems. In the present study, we investigated the effect of N N′-diphenyl-1, 4-phenylenediamine (DPPD) antioxidant activity against mercury chloride- (HgCl₂-) induced renal and hepatic toxicity. Thirty adult female Sprague Dawley rats were divided into three equal groups: the first group was injected with saline only and served as a control, the second group was injected with HgCl₂, and the third group received DPPD + HgCl₂ rats injected with HgCl₂ without treatment showing a significant increase in alkaline phosphatase (ALP), aspartate aminotransferase (AST), alanine aminotransferase (ALT), urea, creatinine, and uric acids compared to control. Moreover, the second group showed a significant reduction in the activity of the antioxidant enzymes (superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH)) in addition to a marked increase in the malondialdehyde (MDA) content, histopathological alterations, collagen deposition, CD8%, CD4%, and TGF-β% in kidney and liver tissues compared with the control group. Treatment with DPPD showed significant recovery (p ≤ 0.001) in all previous parameters and histopathological examination. In conclusion, we suggested that DPPD may have a promising antioxidant capacity, gives it the applicability to be used as a prophylactic agent against mercury-induced hepatorenal cytotoxicity in the future.

The effects of desferrioxamine on cisplatininduced lipid peroxidation and the activities of antioxidant enzymes in rat kidneys

Cisplatin-induced nephrotoxicity is associated with an increase in lipid peroxidation and oxygen free radicals in rat kidneys. In this study, the effects of desferrioxamine were compared to vitamin C and E on cisplatin-induced lipid peroxidation and antioxidant enzyme activities in rat kidneys. Rats were divided into five groups, with 15 Wistar rats in each group. In the control group, rats received 1 mL/100 g isotonic saline solution intraperitoneally (i.p.). In Group II, 10 mg/kg cisplatin i.p. was injected to rats. Thirty minutes before the same dosage of cisplatin administration, 100 mg/kg i.p. vitamin C or E was given to rats in groups III and IV, respectively. Rats in Group V received 250 mg/kg desferrioxamine i.p., before the same dose of cisplatin administration. All rats were killed by cervical dislocation after 72 hours. The kidneys were immediately removed and washed in cold saline. Spectrophotometric method was used for all analyses. While catalase, glutathione reductase (GR), and super oxide dismutase (SOD) levels were found to be significantly decreased (P B < 0.001), malondialdehyde (MDA) (P < 0.05) and hydrogen peroxide (H2O2) (P < 0.001) levels were significantly increased in the cisplatin group when compared to the controls. MDA levels were decreased by desferrioxamine (P < 0.005) as well as vitamin C and E (P < 0.05 and P < 0.001, respectively). These three compounds induced a significant increase in SOD levels (P B < 0.05), but only in the vitamin C group, were SOD levels not significantly different than the levels of the controls (P > 0.05). In the desferrioxamine (P < 0.05), vitamin C and E groups (P < 0.001 for both), the cisplatin elevated H2O2 levels were decreased. None of these drugs had any effect on GR and catalase levels (P > 0.05). Desferrioxamine is useful to prevent cisplatin-induced lipid peroxidation, however, vitamin C and E are more effective on antioxidant enzymes than desferrioxamine.

An integrated view of cisplatin-induced nephrotoxicity and ototoxicity

Cisplatin is one of the most widely-used drugs to treat cancers. However, its nephrotoxic and ototoxic side-effects remain major clinical limitations. Recent studies have improved our understanding of the molecular mechanisms of cisplatin-induced nephrotoxicity and ototoxicity. While cisplatin binding to DNA is the major cytotoxic mechanism in proliferating (cancer) cells, nephrotoxicity and ototoxicity appear to result from toxic levels of reactive oxygen species and protein dysregulation within various cellular compartments. In this review, we discuss molecular mechanisms of cisplatin-induced nephrotoxicity and ototoxicity. We also discuss potential clinical strategies to prevent nephrotoxicity and ototoxicity and their current limitations.

Carboplatin-induced Fanconi-like syndrome in rats: amelioration by pentoxifylline

INTRODUCTION

Carboplatin is a congener of cisplatin used in the treatment of ovarian, head and neck and small-cell lung cancer. However, the clinical efficacy of carboplatin is marred by the development of ROS-dependent nephrotoxicity. The pathophysiological damage inflicted upon the kidney by carboplatin closely resembles to that of Fanconi syndrome.

AIMS AND OBJECTIVES

The present study aimed at inducing Fanconi-like syndrome in rats by administration of carboplatin. Objectives of the study involved evaluation of biochemical parameters coherent to Fanconi-like syndrome. Further, an attempt was made to evaluate the potential therapeutic effect of pentoxifylline in this condition.

RESULTS

The results of the study demonstrated that the urinary excretion profile of carboplatin treated rats closely resembled to that of patients suffering from Fanconi-like condition. Pentoxifylline was able to ameliorate this nephrotoxic condition as suggested by the change in levels of membrane bound ATPases, MDA and GSH. The urinary levels of tyrosine and cysteine correlate well with that of Fanconi-like condition in animals and humans.

CONCLUSION

In lieu of these observations, our study suggested that carboplatin-induced renovascular damage resembles to Fanconi-like condition which can be mitigated by pentoxifylline.

Cisplatin-induced nephrotoxicity and targets of nephroprotection: an update

Cisplatin is a highly effective antitumor agent whose clinical application is limited by the inherent nephrotoxicity. The current measures of nephroprotection used in patients receiving cisplatin are not satisfactory, and studies have focused on the investigation of new possible protective strategies. Many pathways involved in cisplatin nephrotoxicity have been delineated and proposed as targets for nephroprotection, and many new potentially protective agents have been reported. The multiple pathways which lead to renal damage and renal cell death have points of convergence and share some common modulators. The most frequent event among all the described pathways is the oxidative stress that acts as both a trigger and a result. The most exploited pathways, the proposed protective strategies, the achievements obtained so far as well as conflicting data are summarized and discussed in this review, providing a general view of the knowledge accumulated with past and recent research on this subject.

Cisplatin-induced nephrotoxicity is associated with oxidative stress, redox state unbalance, impairment of energetic metabolism and apoptosis in rat kidney mitochondria

The clinical use of cisplatin (cis-diamminedichloroplatinum II) is highly limited by its nephrotoxicity. The precise mechanisms involved in cisplatin-induced mitochondrial dysfunction in kidney have not been completely clarified. Therefore, we investigated in vivo the effects of cisplatin on mitochondrial bioenergetics, redox state, and oxidative stress as well as the occurrence of cell death by apoptosis in cisplatin-treated rat kidney. Adult male Wistar rats weighing 200-220 g were divided into two groups. The control group (n = 8) was treated only with an intraperitoneal (i.p.) injection of saline solution (1 ml per 100 g body weight), and the cisplatin group (n = 8) was given a single injection of cisplatin (10 mg/kg body weight, i.p.). Animals were sacrificed 72 h after the treatment. The cisplatin group presented acute renal failure characterized by increased plasmatic creatinine and urea levels. Mitochondrial dysfunction was evidenced by the decline in membrane electrochemical potential and the substantial decrease in mitochondrial calcium uptake. The mitochondrial antioxidant defense system was depleted, as shown by decreased GSH and NADPH levels, GSH/GSSG ratio, and increased GSSG level. Moreover, cisplatin induced oxidative damage to mitochondrial lipids, including cardiolipin, and oxidation of mitochondrial proteins, as demonstrated by the significant decrease of sulfhydryl protein concentrations and increased levels of carbonylated proteins. Additionally, aconitase activity, which is essential for mitochondrial function, was also found to be lower in the cisplatin group. Renal cell death via apoptosis was evidenced by the increased caspase-3 activity. Results show the central role of mitochondria and the intensification of apoptosis in cisplatin-induced acute renal failure, highlighting a number of steps that might be targeted to minimize cisplatin-induced nephrotoxicity.

Kinetics of Cisplatin and its monohydrated complex with sulfur-containing compounds designed for local otoprotective administration

The anticancer drug cisplatin can cause permanent inner ear damage. We have determined the second-order degradation rate constant, k(Nu), of cisplatin and its more toxic monohydrated complex (MHC) in the presence of each of the sulfur-containing nucleophiles N-acetyl-l-cysteine, l-cysteine methyl ester, 1,3-dimethyl-2-thiourea, d-methionine, and thiosulfate, compounds that are under evaluation for local administration to prevent cisplatin-induced ototoxicity. MHC was isolated from a hydrolysis solution of cisplatin using liquid chromatography (LC). The degradations were evaluated by measuring the disappearance of MHC and cisplatin at 37 degrees C and pH 7.4 in the presence of each of the nucleophiles using LC and photometric detection. The k(Nu) of MHC and of cisplatin was 0.044 M(-1)sec(-1) and 0.012 M(-1)sec(-1) with N-acetyl-l-cysteine, 0.24 M(-1)sec(-1) and 0.067 M(-1)sec(-1) with l-cysteine methyl ester, 0.16 M(-1)sec(-1) and 0.074 M(-1)sec(-1) with 1,3-dimethyl-2-thiourea, 0.070 M(-1)sec(-1) and 0.069 M(-1)sec(-1) with d-methionine, and 3.9 M(-1)sec(-1) and 0.091 M(-1)sec(-1) with thiosulfate, respectively. Our results suggest that thiosulfate, as being the strongest nucleophile, is a promising candidate for local application in order to reduce the inner ear content of MHC and cisplatin. However, otoprotection is a multifactorial event, and it remains to be established how important nucleophilicity is for the effectiveness of the protecting agent.

Effect of chemotherapy on serum end-products of lipid peroxidation in patients with small cell lung cancer: Association with treatment results

Many anti-cancer drugs induce formation of lipid peroxidation products that are toxic for lung cancer cells in vitro. We tested whether changes of serum thiobarbituric acid reactive substances (TBARs) and Schiff's bases (SB) are associated with treatment efficacy in 37 small cell lung cancer (SCLC) patients. Subjects received carboplatin (350 mg/m2, i.v.-Day 1), vincristine (1.3 mg/m2, i.v.-Day 1), and etoposide (120 mg/m2, oral dose-Days 1-4). Then 5 subsequent cycles were repeated at 21-day intervals. Serum TBARs and SB were measured fluorimetrically before and 6, 24h after introduction of the 1st, 3rd and 6th cycles. TBARs and SB levels rose 24 h after 1st chemotherapy in the whole group (2.5+/-1.4 vs. 4.2+/-2.0 micromol/dl, P<0.001 and 26.3+/-16.7 vs. 29.7+/-9.8U(430)/ml, P<0.01, respectively) and the highest increments were in 19 patients with complete or partial response after 1st, 3rd and 6th cycles. In 9 subjects with progressive disease occurring before the 2nd cycle (early progression) TBARs and SB decreased 6 and 24h after the 1st cycle (4.3+/-1.2 vs. 3.4+/-1.4, P<0.05 vs. 2.7+/-0.9 micromol/dl, P<0.05 and 50.2+/-17.0 vs. 36.7+/-13.2, P<0.05 vs. 36.5+/-13.4 U(430)/ml, P<0.01, respectively). Patients survival correlated with the 1st cycle-induced TBARs (r=0.49, P<0.001) and SB (r=0.56, P<0.002) increments. Subjects with negative SB and TBARs increments (n=8) had shorter survival than those (n=29) with positive increments in lipid peroxidation products (log rank test P<0.005). Monitoring of circulatory TBARs and SB may be helpful for screening of SCLC patients with high risk of early disease progression and chemotherapy failure.

The effect of rebamipide on cisplatin-induced nephrotoxicity in rats

This study aimed to evaluate the protective effect of rebamipide (free radical scavenger) against the nephrotoxic effect induced by cisplatin in normal rats. Twenty-four male Wister albino rats were divided equally into four groups: control, rebamipide, cisplatin and cisplatin plus rebamipide-treated groups. Nephrotoxicity was induced with single intravenous (i.v.) cisplatin dose of 6 mg kg(-1)and measured through the estimation of kidney weight, serum albumin (Alb), serum creatinine (Cr), blood urea nitrogen (BUN), kidney glutathione (GSH) and malondialdehyde (MDA) production. In the cisplatin-treated group the kidney weight as a percent of the total body weight, serum Alb, serum Cr, BUN, GSH content and MDA amount were: 0.61+/-0.054%, 2.84+/-0.24 g dl(-1), 2.99+/-0.10 mg dl(-1), 147.08+/-7.46 mg dl(-1), 3.11+/-0.238 micromol g(-1)and 1449. 09+/-127.36 nmol g(-1), respectively. All the previous changes were significantly (P<0.01) different from the corresponding values in the control group. In addition, histopathological examination of the kidney tissue revealed degenerative cellular material and apoptotic tubular cells were seen in the renal tubules. Rebamipide treatment (140 mg kg(-1), i.p.) for 1 week ameliorated all the previous changes and the results recorded for the cisplatin plus rebamipide-treated group were: 0.45+/-0.035%, 4.17+/-0.091 g dl(-1), 1.37+/-0.209 mg dl(-1), 72.25+/-5.14 mg dl(-1), 5.063+/-0.269 micromol g(-1)and 560.23+/-21.98 nmol g(-1)for the previous tests, respectively. Furthermore, significant improvement in the kidney histopathology was observed. The results of this study clearly revealed that rebamipide protected the kidney against the nephrotoxic effect of cisplatin. These results suggest that lipid peroxidation is not the only mechanism by which cisplatin induced nephrotoxicity. More investigations are needed to confirm the effect of rebamipide and at the same time to elucidate the exact mechanism by which cisplatin induces nephrotoxicity.

Effects of antioxidants and Ca2+ in cisplatin-induced cell injury in rabbit renal cortical slices

Effects of antioxidants, reactive oxygen species (ROS) scavengers, and Ca2+ on cisplatin-induced renal cell injury were studied in rabbit renal cortical slices in vitro. Cisplatin induced LDH release and lipid peroxidation, inhibition of PAH uptake, and GSH depletion. These changes were significantly prevented by thiols (DTT and GSH), antioxidants (DPPD and BHA), and an iron chelator (deferoxamine). Superoxide dismutase partially reduced the cisplatin-induced LDH release without affecting the lipid peroxidation and the GSH depletion. Catalase did not affect the LDH release and the lipid peroxidation induced by cisplatin. Hydroxyl radical scavengers prevented the lipid peroxidation, whereas they did not alter the LDH release, the inhibition of PAH uptake, and the GSH depletion induced by cisplatin. Removal of Ca2+ or addition of EGTA to the incubation medium did not alter cisplatin effects on LDH release and lipid peroxidation. Buffering intracellular Ca2+ with quin-2/AM or inhibition of intracellular Ca2+ release with TMB-8 significantly reduced the cisplatin effect on LDH release without any effect on the lipid peroxidation and the GSH depletion. Ruthenium red attenuated the LDH release, the lipid peroxidation, and the inhibition of PAH uptake mediated by cisplatin. La3+ prevented the cisplatin effect on the LDH release, whereas it did not affect the lipid peroxidation, the inhibition of PAH uptake, and the GSH depletion by cisplatin. These results suggest that cisplatin induces a lethal cell injury by lipid peroxidation-dependent and -independent mechanisms and that the cell injury and the lipid peroxidation by cisplatin are iron-dependent. In addition, the data indicate that the Ca2+ released from intracellular stores, but not the Ca2+ moved from extracellular space, plays a role in the cisplatin-induced cell injury independent of lipid peroxidation.

Comparative adverse effect profiles of platinum drugs

Since the discovery of the biologically active platinum complexes 30 years ago, 2 agents have become widely established in clinical oncology practice. Both cisplatin and carboplatin are platinum(II) complexes with 2 ammonia groups in the cis- position. However, they differ in their solubility, chemical reactivity, dichloride or alicyclic oxygenated leaving groups, pharmacokinetics and toxicology. Cisplatin causes severe renal tubular damage and reduces glomerular filtration, and requires concurrent saline hydration and mannitol diuresis to eliminate potentially lethal and unacceptable damage to the kidneys. Carboplatin, at conventional doses, causes no decrease in glomerular filtration and only minor transient elevations in urinary enzymes. Cisplatin is the most emetic cancer drug in common use, while nausea and vomiting associated with carboplatin are moderately severe. Serotonin release from enterochromaffin gut mucosal cells and stimulation of serotonin 5-HT3-receptors mediates acute emesis. Selective inhibitors of the 5-HT3-receptor protect against cisplatin- and carboplatin-induced nausea and vomiting. Peripheral neurotoxicity is the most dose-limiting problem associated with cisplatin. Loss of vibration sense, paraesthesia and sensory ataxia comes on after several treatment cycles. Carboplatin, however, is relatively free from peripheral neurotoxicity. Audiometry shows cisplatin-induced ototoxicity in 75 to 100% of patients, which may be associated with tinnitus and hearing loss. Ototoxicity is rare with conventional dose carboplatin therapy. Monitoring hearing with audiograms may identify early signs before significant impairment occurs. Cisplatin causes mild haematological toxicity to all 3 blood lineages. Haematological toxicity is dose-limiting for carboplatin, with thrombocytopenia being a greater problem than leucopenia. Although carboplatin is not toxic to the kidney, renal function markedly affects the severity of carboplatin-induced thrombocytopenia. The major clearance mechanism of cisplatin is irreversible binding in plasma and tissues, while carboplatin is cleared by glomerular filtration. Metabolism of cisplatin to aqua, amino acid and protein species is extensive, whereas carboplatin exists mainly as the free unchanged form. Strong relationships between carboplatin renal clearance, glomerular filtration rate, area under the plasma concentration-time curve (AUC) of filterable platinum and severity of thrombocytopenia have prompted dose adjustment according to renal function. New analogues such as JM216 offer the potential advantages of oral administration and few nonhaematological toxicities. Analogues based on the diaminocyclohexane ligand have encountered problematic neurotoxicity.

Modulation of sodium-coupled uptake and membrane fluidity by cisplatin in renal proximal tubular cells in primary culture and brush-border membrane vesicles

The proximal tubule appears to be the main target for the adverse effects of cis-diamminedichloroplatinum (II) (cDDP). We evaluated the early effects of cDDP at concentrations (3 to 67 microM) lower that those which alter cell viability, on three apical transport systems and on the physical state of the brush border membrane (BBM) in rabbit proximal tubule (RPT) cells in primary culture. The maximal effect, corresponding to a 30% decrease in Na(+)-coupled uptake of phosphate (Pi) and alpha-methylglucopyranoside (MGP) and a twofold increase in Na(+)-coupled alanine uptake, was obtained at 17 microM (5 micrograms/ml) cDDP and occurred through a modification of their affinity. At this concentration, cDDP increased BBM fluidity and decreased the BBM cholesterol content by 28%, without increasing the permeability of tight junctions. To clarify the role of cDDP-induced increase in BBM fluidity on alterations of Na(+)-coupled uptake, these parameters were also investigated in BBM vesicles isolated from rabbit renal cortex directly exposed to cDDP. cDDP induced a concentration-dependent inhibition of Na(+)-coupled uptake of MGP, Pi and alanine in BBM vesicles from the renal cortex, associated with a decrease in protein sulfhydryl content, without modifying BBM fluidity. Our findings strongly suggest that the cDDP-induced increase in BBM fluidity in RPT cells results from an indirect mechanism, possibly an alteration of cholesterol metabolism, and did not play a major role in the cDDP-induced inhibition of Na+/Pi and Na+/glucose cotransport systems that may be mainly mediated through a direct chemical interaction with essential sulfhydryl groups of the transporters.

Nephrotoxicity of acyclovir and cis-diamminedichloroplatinum(II)--effect of co-administration in rats

The effect of co-administration of acyclovir and cis-diamminedichloroplatinum(II) (cisplatin) on nephrotoxicity in male Wistar rats was investigated. Animals received acyclovir (15 mg/kg body weight, s.c., three times per day for 5 days) or cisplatin (5 mg/kg body weight, i.p., one single injection) or a combination of both drugs. Acyclovir plasma levels were determined after one single acyclovir s.c. injection. Urines were monitored for volume, pH, osmolality and excretion of N-acetyl-beta-D-glucosaminidase (NAG), lysozyme and total protein. Concentrations of blood urea nitrogen and plasma creatinine were determined on day 6. Renal cortical slices were monitored to assess the accumulation of weak organic bases (tetraethylammonium) and acids (p-aminohippurate). Cisplatin induced a marked increase in the excretion of NAG, lysozyme and total protein and an increase in urine volume, plasma creatinine and blood urea nitrogen. Urine osmolality and accumulation of p-aminohippurate were depressed by cisplatin. Acyclovir treatment alone caused no significant symptoms of nephrotoxicity. Co-administration did not impair renal function more than cisplatin treatment alone, excepting a slight rise in lysozyme excretion on day 6. Short-term antiviral therapy with acyclovir, concomitant to cisplatin treatment, may bring, if at all, a slightly increased nephrotoxic risk.