Amelioration of cisplatin nephrotoxicity by genetic or pharmacologic blockade of prostaglandin synthesis

COX-2 but not mPGES-1 contributes to renal PGE2 induction and diabetic proteinuria in mice with type-1 diabetes

Prostaglandin E2 (PGE2) has been implicated to play a pathogenic role in diabetic nephropathy (DN) but its source remains unlcear. To elucidate whether mPGES-1, the best characterized PGE2 synthase, was involved in the development of DN, we examined the renal phenotype of mPGES-1 KO mice subjected to STZ-induced type-1 diabetes. After STZ treatment, mPGES-1 WT and KO mice presented the similar onset of diabetes as shown by similar elevation of blood glucose. Meanwhile, both genotypes of mice exhibited similar increases of urinary and renal PGE2 production. In parallel with this comparable diabetic status, the kidney injury indices including the urinary albumin excretion, kidney weight and the kidney histology (PAS staining) did not show any difference between the two genotypes. By Western-blotting and quantitative qRT-PCR, mPGES-1, mPGES-2, cPGES and 15-hydroxyprostaglandin dehydrogenase (15-PGDH) remain unaltered following six weeks of diabetes. Finally, a selective COX-2 inhibitor celecoxib (50 mg/kg/day) was applied to the STZ-treated KO mice, which resulted in significant reduction of urinary albumin excretion (KO/STZ: 141.5±38.4 vs. KO/STZ + Celebrex: 48.7±20.8 ug/24 h, p<0.05) and the blockade of renal PGE2 induction (kidney: KO/STZ: 588.7±89.2 vs. KO/STZ + Celebrex: 340.8±58.7 ug/24 h, p<0.05; urine: KO/STZ 1667.6±421.4 vs. KO/STZ + Celebrex 813.6±199.9 pg/24 h, p<0.05), without affecting the blood glucose levels and urine volume. Taken together, our data suggests that an as yet unidentified prostaglanind E synthase but not mPGES-1 may couple with COX-2 to mediate increased renal PGE2 sythsesis in DN.

Magnesium protects against cisplatin-induced acute kidney injury by regulating platinum accumulation

Despite its success as a potent antineoplastic agent, ∼25% of patients receiving cisplatin experience acute kidney injury (AKI) and must discontinue therapy. Impaired magnesium homeostasis has been linked to cisplatin-mediated AKI, and because magnesium deficiency is widespread, we examined the effect of magnesium deficiency and replacement on cisplatin-induced AKI in physiologically relevant older female mice. Magnesium deficiency significantly increased cisplatin-associated weight loss and markers of renal damage (plasma blood urea nitrogen and creatinine), histological changes, inflammation, and renal cell apoptosis and modulated signaling pathways (e.g., ERK1/2, p53, and STAT3). Conversely, these damaging effects were reversed by magnesium. Magnesium deficiency alone significantly induced basal and cisplatin-mediated oxidative stress, whereas magnesium replacement attenuated these effects. Similar results were observed using cisplatin-treated LLC-PK1 renal epithelial cells exposed to various magnesium concentrations. Magnesium deficiency significantly amplified renal platinum accumulation, whereas magnesium replacement blocked the augmented platinum accumulation after magnesium deficiency. Increased renal platinum accumulation during magnesium deficiency was accompanied by reduced renal efflux transporter expression, which was reversed by magnesium replacement. These findings demonstrate the role of magnesium in regulating cisplatin-induced AKI by enhancing oxidative stress and thus promoting cisplatin-mediated damage. Additional in vitro experiments using ovarian, breast, and lung cancer cell lines showed that magnesium supplementation did not compromise cisplatin's chemotherapeutic efficacy. Finally, because no consistently successful therapy to prevent or treat cisplatin-mediated AKI is available for humans, these results support developing more conservative magnesium replacement guidelines for reducing cisplatin-induced AKI in cancer patients at risk for magnesium deficiency.

Nephroprotective activities of rosmarinic acid against cisplatin-induced kidney injury in mice

Rosmarinic acid (RA) is a natural phenolic compound with a broad range of applications, from food preservatives to cosmetics. Increasing amounts of evidence suggests its beneficial effects against various pathological conditions. The aim of this study was to investigate the therapeutic activity of rosmarinic acid (RA) against cisplatin (CP)-induced nephrotoxicity. RA was administered by oral gavage at doses of 1, 2 and 5mg/kg for two successive days, 48 h after intraperitoneal CP injection (13 mg/kg). Twenty four hours later, mice were sacrificed. Treatment with RA significantly ameliorated histopathological changes and the increase in serum creatinine and blood urea nitrogen (BUN) induced by CP. Oxidative stress induced by CP, evidenced by increased renal 4-hydroxynonenal (4-HNE), cytochrome P450 2E1 (CYP2E1) and heme oxygenase (HO-1) expression, was significantly reduced by RA administration. Moreover, RA inhibited the expression of nuclear factor-kappaB (NF-κB) and tumor necrosis factor-α (TNF-α), indicating the inhibition of inflammation. Additionally, RA exhibited antiapoptotic activity through the reduction of p53, phosphorylated p53 and active caspase-3 expression in the kidneys. These findings show that RA ameliorates CP-induced oxidative stress, inflammation and apoptosis in the kidneys. The nephroprotective activity of RA could be, at least in part, attributed to reduced CYP2E1 expression.

New Insights into the PPAR γ Agonists for the Treatment of Diabetic Nephropathy

Diabetic nephropathy (DN) is a severe complication of diabetes and serves as the leading cause of chronic renal failure. In the past decades, angiotensin-converting enzyme inhibitors (ACEIs)/angiotensin II receptor blockers (ARBs) based first-line therapy can slow but cannot stop the progression of DN, which urgently requests the innovation of therapeutic strategies. Thiazolidinediones (TZDs), the synthetic exogenous ligands of nuclear receptor peroxisome proliferator-activated receptor- γ (PPAR γ ), had been thought to be a promising candidate for strengthening the therapy of DN. However, the severe adverse effects including fluid retention, cardiovascular complications, and bone loss greatly limited their use in clinic. Recently, numerous novel PPAR γ agonists involving the endogenous PPAR γ ligands and selective PPAR γ modulators (SPPARMs) are emerging as the promising candidates of the next generation of antidiabetic drugs instead of TZDs. Due to the higher selectivity of these novel PPAR γ agonists on the regulation of the antidiabetes-associated genes than that of the side effect-associated genes, they present fewer adverse effects than TZDs. The present review was undertaken to address the advancements and the therapeutic potential of these newly developed PPAR γ agonists in dealing with diabetic kidney disease. At the same time, the new insights into the therapeutic strategies of DN based on the PPAR γ agonists were fully addressed.

Metabonomics study on nephrotoxicity induced by intraperitoneal and intravenous cisplatin administration using rapid resolution liquid chromatography coupled with quadrupole-time-of-flight mass spectrometry (RRLC-Q-TOF-MS)

Metabonomics was used to find characteristics of nephrotoxicity induced by IP or IV injection of cisplatin.

Normobaric hyperoxia preconditioning ameliorates cisplatin nephrotoxicity

BACKGROUND

Cisplatin is a potent anticancer drug, but its nephrotoxicity limits the clinical use of it. To reduce the Cisplatin-induced nephrotoxicity, various interventions have been implicated. The aim of this study was to examine whether preconditioning with normobaric hyperoxia would prevent Cisplatin-induced nephrotoxicity in patient with solid tumor.

METHODS

In a prospective study, 80 adult patients with solid tumor who were treated with Cisplatin between February 2011 and December 2011 were included. Forty-three patients were exposed to pure oxygen via non-rebreathing reservoir mask which increased the provided oxygen rate to 60% oxygen for 2 hours at 48, 24, and 6 hours before intravenous administration of Cisplatin and 37 patients received only Cisplatin as a control group. Estimated glomerular filtration rate (eGFR) calculated in all patients on day 1 before and on days 1, 3, 6, 30 after Cisplatin exposures.

RESULTS

Patients treated with Cisplatin and 60% oxygen showed a mild improvement in eGFR and mild reduction of serum creatinine after 30 days with statistically mild significant differences (p = 0.048).

CONCLUSION

This study showed that normobaric and intermittent precondition of 60% oxygen prior to Cisplatin treatment had an acute transient adverse effect on renal function; however, the improvement of renal function will be seen after 30 days. Thus, it may help to prevent Cisplatin nephrotoxicity.

Amelioration of cisplatin-induced mouse renal lesions by a cyclooxygenase (COX)-2 selective inhibitor

In this study, we investigated the effects of the cyclooxygenase (COX)-2 selective inhibitor, meloxicam, on cisplatin-induced inflammation, oxidative stress and renal lesions in BALB/c mice. A single cisplatin injection (13 mg/kg, i.p.) significantly increased plasma creatinine, blood urea nitrogen and urinary glucose accompanied by a concomitant increase in COX-2 mRNA and COX-2 protein levels. These changes in renal lesion parameters were diminished by simultaneous treatment of meloxicam (0.7 mg/kg/day in drinking water). The expression of oxidative stress markers, p47(phox), p67(phox), hemoxygenase-1 (HO-1), nicotinamide adenine dinucleotide phosphate (NADPH) oxidase 2 (NOX2) and 4-hydroxy-2-nonenal (4-HNE)-modified protein were increased with cisplatin injection. Simultaneous treatment of meloxicam with cisplatin significantly inhibited the increase in p47(phox), HO-1 and 4-HNE-modified protein. The phosphorylation of extracellular regulated kinase (ERK) and c-jun-N-terminal kinase (JNK) were increased with cisplatin injection, but these changes were inhibited by meloxicam. Moreover, concomitant meloxicam treatment also prevented the cisplatin-induced infiltration of macrophages to the tubulointerstitial area. These results suggest that meloxicam can ameliorate cisplatin-induced mouse renal lesions, potentially through the inhibition of inflammatory and oxidative stress responses.

Novel orally active epoxyeicosatrienoic acid (EET) analogs attenuate cisplatin nephrotoxicity

Nephrotoxicity severely limits the use of the anticancer drug cisplatin. Oxidative stress, inflammation, and endoplasmic reticulum (ER) stress contribute to cisplatin-induced nephrotoxicity. We developed novel orally active epoxyeicosatrienoic acid (EET) analogs and investigated their prophylactic effect in cisplatin-induced nephrotoxicity in rats. Cisplatin-induced nephrotoxicity was manifested by increases in blood urea nitrogen, plasma creatinine, urinary N-acetyl-β-(d)-glucosaminidase activity, kidney injury molecule 1, and histopathology. EET analogs (10 mg/kg/d) attenuated cisplatin-induced nephrotoxicity by reducing these renal injury markers by 40-80% along with a 50-70% reduction in renal tubular cast formation. This attenuated renal injury is associated with reduced oxidative stress, inflammation, and ER stress evident from reduction in related biomarkers and in the renal expression of genes involved in these pathways. Moreover, we demonstrated that the attenuated nephrotoxicity correlated with decreased apoptosis that is associated with 50-90% reduction in Bcl-2 protein family mediated proapoptotic signaling, reduced renal caspase-12 expression, and a 50% reduction in renal caspase-3 activity. We further demonstrated in vitro that the protective activity of EET analogs does not compromise the anticancer effects of cisplatin. Collectively, our data provide evidence that EET analogs attenuate cisplatin-induced nephrotoxicity by reducing oxidative stress, inflammation, ER stress, and apoptosis without affecting the chemotherapeutic effects of cisplatin.

Microsomal Prostaglandin E2 Synthase-1

The prostanoids and leukotrienes (LTs) formed from arachidonic acid (AA) via the cyclooxygenase (COX)-1/2 and 5-lipoxygenase (5-LO) pathway, respectively, mediate inflammatory responses, chronic tissue remodelling, cancer, asthma and autoimmune disorders, but also possess homeostatic functions in the gastrointestinal tract, uterus, brain, kidney, vasculature and host defence. Based on the manifold functions of these eicosanoids, the clinical use of non-steroidal anti-inflammatory drugs (NSAIDs), a class of drugs that block formation of all prostanoids, is hampered by severe side-effects including gastrointestinal injury, renal irritations and cardiovascular risks. Therefore, anti-inflammatory agents interfering with eicosanoid biosynthesis require a well-balanced pharmacological profile to minimize these on-target side-effects. Current anti-inflammatory research aims at identifying compounds that can suppress the massive formation of pro-inflammatory prostaglandin (PG)E2 without affecting homeostatic PGE2 and PGI2 synthesis. The inducible microsomal prostaglandin E2 synthase-1 (mPGES-1) is one promising target enzyme. We will give an overview about the structure, regulation and function of mPGES-1 and then present novel inhibitors of mPGES-1 that may possess a promising pharmacological profile.

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.

Chemotherapy enhances metastasis formation via VEGFR-1-expressing endothelial cells

Recent studies suggest that chemotherapy, in addition to its cytotoxic effects on tumor cells, can induce a cascade of host events to support tumor growth and spread. Here, we used an experimental pulmonary metastasis model to investigate the role of this host response in metastasis formation. Mice were pretreated with chemotherapy and after clearance of the drugs from circulation, tumor cells were administered intravenously to study potential "protumorigenic" host effects of chemotherapy. Pretreatment with the commonly used chemotherapeutic agents cisplatin and paclitaxel significantly enhanced lung metastasis in this model. This corresponded to enhanced adhesion of tumor cells to an endothelial cell monolayer that had been pretreated with chemotherapy in vitro. Interestingly, chemotherapy exposure enhanced the expression of VEGF receptor 1 (VEGFR-1) on endothelial cells both in vitro and in vivo. Administration of antibodies targeting VEGFR-1 reversed the early retention of tumor cells in the lungs, thereby preventing the formation of chemotherapy-induced pulmonary metastases. The data indicate that chemotherapy-induced expression of VEGFR-1 on endothelial cells can create an environment favorable to tumor cell homing. Inhibition of VEGFR-1 function may therefore be used to counteract chemotherapy-induced retention of tumor cells within the metastatic niche, providing a novel level of tumor control in chemotherapy.

Salubrinal, an eIF2α dephosphorylation inhibitor, enhances cisplatin-induced oxidative stress and nephrotoxicity in a mouse model

Although cisplatin attacks various tumors with remarkable efficacy, its clinical usage has been limited by its side effects, particularly nephrotoxicity. Salubrinal, a selective eukaryotic translation initiation factor 2 subunit α (eIF2α) dephosphorylation inhibitor, has been found to protect cells from endoplasmic reticulum (ER)-stress-induced cytotoxicity. In this study, we hypothesized that salubrinal would protect against cisplatin-induced nephrotoxicity in a mouse model. Cisplatin treatment significantly increased serum blood urea nitrogen and creatinine levels, renal kidney injury marker (kim-1) mRNA expression, renal cell apoptosis, and renal histopathological changes in mice. Unexpectedly, administration of salubrinal significantly enhanced the cisplatin-induced nephrotoxicity in mice. Salubrinal by itself did not induce alterations in the function or histomorphology of mouse kidneys. Salubrinal significantly enhanced the phosphorylation of eIF2α, the protein expression of activating transcription factor 4 and CCAAT/enhancer binding protein homologous protein, and the cleavage of caspases 12, 9, and 3 in the kidneys of cisplatin-treated mice. Moreover, salubrinal enhanced the cisplatin-induced oxidative stress in the kidneys. The antioxidant N-acetylcysteine significantly reversed the increased renal lipid peroxidation, activated renal caspase cascade, and increased blood BUN and creatinine in cisplatin-alone- or cisplatin plus salubrinal-treated mice. These findings suggest that salubrinal aggravates cisplatin-induced nephrotoxicity through the enhancement of oxidative stress and ER stress-related cell apoptosis.

Interleukin-6 plays a protective role in development of cisplatin-induced acute renal failure through upregulation of anti-oxidative stress factors

AIMS

Cisplatin, a major chemotherapeutic agent, accumulates in proximal tubules of the kidneys and causes acute renal failure dose-dependently. We previously reported that cisplatin induced more severe renal dysfunction in interleukin-6 (IL-6) knockout (IL-6(-/-)) mice than in wild-type (WT) mice. Expression of a pro-apoptotic protein was significantly increased with cisplatin in IL-6(-/-) mice compared to that in WT mice. IL-6, locally expressed in renal tubular cells after cisplatin administration, prevents the development of renal dysfunction at an early stage. In the present study, we focused on downstream signals of IL-6 and oxidative stress induced by cisplatin in order to evaluate the protective role of IL-6 in the development of acute renal failure.

MAIN METHODS

WT and IL-6(-/-) mice were given either cisplatin (30 mg/kg) or saline intraperitoneally. Blood and kidney samples were collected at 24h and 72 h after cisplatin administration. The changes in expression of 4-hydroxy-2-nonenal protein (4-HNE, oxidative stress marker) and cyclooxygenase-2 (cox-2), activities of superoxide dismutases and caspase-3, and phosphorylation of extracellular signal-regulated kinase (ERK) were examined.

KEY FINDINGS

Cisplatin increased the expression of 4-HNE and cox-2, and phosphorylation of ERK in IL-6(-/-) mice than in WT mice. On the other hand, activity of superoxide dismutase, an anti-oxidative enzyme, was significantly decreased in the kidney obtained from IL-6(-/-) mice after cisplatin administration.

SIGNIFICANCE

Our findings suggest that IL-6 plays a protective role in the development of cisplatin-induced acute renal failure through upregulation of anti-oxidative stress factors.