Protective role of edaravone against cisplatin-induced ototoxicity in an auditory cell line

Cisplatin-Induced Hearing Loss, Oxidative Stress, and Antioxidants as a Therapeutic Strategy-A State-of-the-Art Review

Cisplatin is an established component of treatment protocols for various solid malignancies but carries a significant potential for serious adverse effects. Ototoxicity from cisplatin treatment is an important dose-limiting toxicity that manifests as bilateral, progressive, irreversible, dose-dependent sensorineural hearing loss, ear pain, tinnitus, and vestibular dysfunction. Despite the recent approval of sodium thiosulphate for the prevention of cisplatin-induced hearing loss (CIHL) in pediatric patients, structured prevention programs are not routinely implemented in most hospitals, and reducing platinum-induced ototoxicity in adults remains an important clinical problem without established treatment options. Cochlear oxidative stress plays a fundamental role in CIHL. Here, we review the molecular mechanisms leading to oxidative stress in CIHL and the clinical and preclinical studies testing antioxidants in CIHL to guide future clinical trials in assessing the efficacy and safety of candidate antioxidant compounds in this clinical setting.

Apoptosis, autophagy, ferroptosis, and pyroptosis in cisplatin-induced ototoxicity and protective agents

Cisplatin is widely used to treat various solid tumors. However, its toxicity to normal tissues limits its clinical application, particularly due to its ototoxic effects, which can result in hearing loss in patients undergoing chemotherapy. While significant progress has been made in preclinical studies to elucidate the cellular and molecular mechanisms underlying cisplatin-induced ototoxicity (CIO), the precise mechanisms remain unclear. Moreover, the optimal protective agent for preventing or mitigating cisplatin-induced ototoxicity has yet to be identified. This review summarizes the current understanding of the roles of apoptosis, autophagy, ferroptosis, pyroptosis, and protective agents in cisplatin-induced ototoxicity. A deeper understanding of these cell death mechanisms in the inner ear, along with the protective agents, could facilitate the translation of these agents into clinical therapeutics, help identify new therapeutic targets, and provide novel strategies for cisplatin-based cancer treatment.

Edaravone: A Novel Possible Drug for Cancer Treatment?

Despite significant advancements in understanding the causes and progression of tumors, cancer remains one of the leading causes of death worldwide. In light of advances in cancer therapy, there has been a growing interest in drug repurposing, which involves exploring new uses for medications that are already approved for clinical use. One such medication is edaravone, which is currently used to manage patients with cerebral infarction and amyotrophic lateral sclerosis. Due to its antioxidant and anti-inflammatory properties, edaravone has also been investigated for its potential activities in treating cancer, notably as an anti-proliferative and cytoprotective drug against side effects induced by traditional cancer therapies. This comprehensive review aims to provide updates on the various applications of edaravone in cancer therapy. It explores its potential as a standalone antitumor drug, either used alone or in combination with other medications, as well as its role as an adjuvant to mitigate the side effects of conventional anticancer treatments.

5,7-Dihydroxy-4-methylcoumarin modulates the JNK/FoxO1 signaling pathway to attenuate cisplatin-induced ototoxicity by suppressing oxidative stress and apoptosis in vitro

5,7-Dihydroxy-4-methylcoumarin (D4M) is attributed to free radical scavenging effects, with wide application for anti-oxidation. This work aimed to assess D4M's impact on cisplatin-induced ototoxicity. The cell viability was estimated with CCK-8 assay. Apoptosis was detected by the Annexin V-FITC and PI assay. The reactive oxygen species (ROS) level was determined by MitoSOX-Red and CellROX-Green probes. Mitochondrial membrane potential was analyzed with TMRM staining. Immunofluorescence was utilized for hair cells and spiral ganglion neuron detection. Apoptosis-associated proteins were assessed by cleaved caspase-3 and TUNEL staining. These results showed that D4M pretreatment protected hair cells from cisplatin-induced damage, increased cell viability, and decreased apoptosis in House Ear Institute-Organ of Corti1 (HEI-OC1) cells and neonatal mouse cochlear explants. D4M significantly inhibited cisplatin-induced mitochondrial apoptosis and reduced ROS accumulation. In addition, the protective effect of D4M on cisplatin-induced ototoxicity was also confirmed in cochlear hair cells and spiral ganglion neurons in neonatal mice. Mechanistic studies showed that D4M markedly downregulated p-JNK and elevated the expression ratio of p-FoxO1/FoxO1, thereby reducing cisplatin-induced caspase-dependent apoptosis. Meanwhile, D4M-related protection of HEI-OC1 cells was significantly blunted by JNK signaling induction with anisomycin. This study supports the possibility that D4M may be used as a new compound to prevent cisplatin-related hearing loss.

Edaravone alleviates methotrexate-induced testicular injury in rats: Implications on inflammation, steroidogenesis, and Akt/p53 signaling

Edaravone (ED) is a neuroprotective drug with beneficial effects against several disorders due to its prominent antioxidant activity. However, its effect against methotrexate (MTX)-induced testicular damage was not previously investigated. Therefore, we aimed to investigate the ability of ED to prevent the oxidative stress, inflammation, and apoptosis induced by MTX on the rat testis and to examine whether ED administration modulated the Akt/p53 signaling and steroidogenesis process. Rats were allocated into; Normal, ED (20 mg/kg, PO, for 10 days), MTX (20 mg/kg, i.p., on the 5^th day), and ED + MTX groups. The results showed that MTX group exhibited higher serum activities of ALT, AST, ALP, and LDH in addition to histopathological alterations in the rat testis, compared to normal group. Furthermore, MTX induced down-regulation of the steroidogenic genes; StAR, CYP11a1, and HSD17B3 and reduced FSH, LH, and testosterone levels. The MTX group also showed higher levels of MDA, NO, MPO, NF-kB, TNF-α, IL-6, IL-1β, Bax, and caspase 3, as well as, lower levels of GSH, GPx, SOD, IL-10, Bcl2 compared to normal rats, p < 0.05. In addition, MTX treatment resulted in increased p53 expression and decreased p-Akt expression. Remarkably, ED administration significantly prevented all the biochemical, genetic, and histological damage induced by MTX. Hence, ED treatment protected the rat testis from apoptosis, oxidative stress, inflammation, and impaired steroidogenesis induced by MTX. This novel protective effect was mediated by decreasing p53 while increasing p-Akt protein expression.

Regulation of PPARγ/CPT-1 expression ameliorates cochlear hair cell injury by regulating cellular lipid metabolism and oxidative stress

This study aimed to investigate the protective effects of PPARγ/CPT-1 regulation on cisplatin-induced cochlear hair cell injury. The viability, apoptosis and mitochondrial membrane potential of cisplatin-induced HEI-OC1 cells were determined by CCK-8 assay, TUNEL and JC-1 staining, respectively. The oxidative stress and lipid metabolism were detected by the assay kits of MDA, ROS, SOD, CAT, TG and FFA. The transfection efficiency of overexpression (OV)-PPARG and OV-CPT1A was examined by RT-qPCR and the expressions of apoptosis- and lipid metabolism-related proteins were detected by western blot. As a result, cisplatin with varying concentrations (5, 10, 30 μM) suppressed the viability, promoted the apoptosis and hindered the mitochondrial function of HEI-OC1 cells, accompanied with up-regulated expressions of Bax and cleaved caspase-3 and down-regulated expression of Bcl-2. The oxidative stress was aggravated and lipid metabolism was inhibited by cisplatin (5, 10, 30 μM) induction, evidenced by the increased levels of MDA, ROS, TG, FFA and the decreased levels of SOD and CAT. Overexpression of PPARG or CPT1A could improve the viability, mitochondrial function, lipid metabolism and suppress the oxidative stress and apoptosis of cisplatin-induced HEI-OC1 cells. In conclusion, up-regulation of PPARG or CPT1A ameliorated cochlear hair cell injury by improving cellular lipid metabolism and inhibiting oxidative stress.

Gstm1/Gstt1 is essential for reducing cisplatin ototoxicity in CBA/CaJ mice

Cisplatin is a widely used chemotherapeutic agent. However, its clinical utility is limited because of cisplatin-induced ototoxicity. Glutathione S-transferase (GST) was found to play a vital role in reducing cisplatin ototoxicity in mice. Deletion polymorphisms of GSTM1 and GSTT1, members of the GST family, are common in humans and are presumed to be associated with cisplatin-induced hearing impairment. However, the specific roles of GSTM1 and GSTT1 in cisplatin ototoxicity are not completely clear. Here, under cisplatin treatment, simultaneous deletion of Gstm1 and Gstt1 lead to a more profound hearing loss in CBA/CaJ mice (Gstm1/Gstt1-DKO) than in wild-type mice. The Gstm1/Gstt1-DKO mice, in which phase II detoxification genes were upregulated, exhibited more severe oxidative stress and higher outer hair cell apoptosis in the cochleae than the control mice. Thus, our study revealed that Gstm1 and Gstt1 protect auditory hair cells from cisplatin-induced ototoxicity in the CBA/CaJ mice, and genetic screening for GSTM1 and GSTT1 polymorphisms could help determine a standard cisplatin dose for cancer patients undergoing chemotherapy.

Cisplatin-induced ototoxicity: Updates on molecular mechanisms and otoprotective strategies

Cisplatin is a highly effective antitumor drug generally used in the treatment of solid malignant tumors. However, cisplatin causes severe side effects such as bone marrow depression, nephrotoxicity, and ototoxicity, thus limiting its clinical application. The incidence of ototoxicity induced by cisplatin ranges from 20% to 70%, and it usually manifests as a progressive, bilateral and irreversible hearing loss. Although the etiology of cisplatin-induced ototoxicity remains unclear, an increasing body of evidence suggests that the ototoxicity of cisplatin is mainly related to the production of reactive oxygen species and activation of apoptotic pathway in cochlear tissues. Many drugs have been well proved to protect cisplatin-induced hearing loss in vitro and in vivo. However, the anti-tumor effect of cisplatin is also weakened by systemic administration of those drugs for hearing protection, especially antioxidants. Therefore, establishing a local administration strategy contributes to the otoprotection without affecting the effect of cisplatin. This review introduces the pathology of ototoxicity caused by cisplatin, and focuses on recent developments in the mechanisms and protective strategies of cisplatin-induced ototoxicity.

Overview of cisplatin-induced neurotoxicity and ototoxicity, and the protective agents

Cisplatin has dramatically improved the survival rate of cancer patients, but it has also increased the prevalence of hearing and neurological deficits in this population. Cisplatin induces ototoxicity, peripheral (most prevalent) and central (rare) neurotoxicity. This review addresses the ototoxicity and the neurotoxicity associated with cisplatin-based chemotherapy, providing an integrated view of the potential protective agents that have been evaluated in vitro, in vivo and in clinical trials, their targets and mechanisms of protection and their effects on the antitumor activity of cisplatin. So far, the findings are insufficient to support the use of any oto- or neuroprotective agent before, during or after cisplatin chemotherapy. Despite their promising effects in vitro and in animal studies, many agents have not been evaluated in clinical trials. Additionally, the clinical trials have limitations concerning the sample size, controls, measurement, heterogeneous groups, several arms of treatment, short follow-up or no blinding. Besides that, for most agents, the effects on the antitumor activity of cisplatin have not been evaluated in tumor-bearing animals, which discourages clinical trials. Further well-designed randomized controlled clinical trials are necessary to definitely demonstrate the effectiveness of the oto- or neuroprotective agents proposed by animal and in vitro studies.

Increased oxidative stress, inflammation, and glutamate: Potential preventive and therapeutic targets for hearing disorders

Hearing disorders constitute one of the major health concerns in the USA. Decades of basic and clinical studies have identified numerous ototoxic agents and investigated their modes of action on the inner ear, utilizing tissue culture as well as animal and human models. Current preventive and therapeutic approaches are considered unsatisfactory. Therefore, additional modalities should be developed. Many studies suggest that increased levels of oxidative stress, chronic inflammation, and glutamate play an important role in the initiation and progression of damage to the inner ear leading to hearing impairments. To prevent these cellular deficits, antioxidants, anti-inflammatory agents, and antagonists of glutamate receptor have been used individually or in combination with limited success. It is essential, therefore, to simultaneously enhance the levels of antioxidant enzymes by activating the Nrf2 (a nuclear transcriptional factor) pathway, dietary and endogenous antioxidant compounds, and B12-vitamins in order to reduce the levels of oxidative stress, chronic inflammation, and glutamate at the same time. This review presents evidence to show that increased levels of these cellular metabolites, biochemical or factors are involved in the pathogenesis of cochlea leading to hearing impairments. It presents scientific rationale for the use of a mixture of micronutrients that may decrease the levels of oxidative damage, chronic inflammation, and glutamate at the same time. The benefits for using oral administration of proposed micronutrient mixture in humans are presented. Animal and limited human studies indirectly suggest that orally administered micronutrients can accumulate in the inner ear. Therefore, this route of administration may be useful in prevention, and in combination with standard care, in improved management of hearing problems following exposure to well-recognized and studied ototoxic agents, such as noise, cisplatin, aminoglycoside antibiotics, and advanced age.

Cisplatin-induced ototoxicity involves interaction of PRMT3 and cannabinoid system

This study investigated whether protein arginine methyltransferase (PRMT) and the cannabinoid system are involved in cisplatin-induced ototoxicity. Cisplatin increased cytosine-cytosine-adenosine-adenosine-thymidine-enhancer-binding protein homologous protein expression. This effect is indicative of an increase in endoplasmic reticulum (ER) stress, and apoptosis signaling including cleavage of caspase-3, caspase-9, poly-adenosine diphosphate-ribose polymerase, and phospho-p53, as well as expression of PRMT3, PRMT4 and fatty acid amide hydrolase (FAAH)1 in House Ear Institute-Organ of Corti 1 (HEI-OC1) cells. In addition, overexpression of PRMT3 or PRMT4 increased the expression of FAAH1 expression, apoptosis, and ER stress signaling in HEI-OC1 cells, whereas PRMT3 or PRMT4 knockdown had the opposite effect. Furthermore, overexpression of FAAH1 increased apoptosis and ER stress, but expression of the PRMTs was unchanged. In addition, a cannabinoid 1 receptor agonist and FAAH inhibitor attenuated apoptosis and ER stress, while cisplatin increased the binding of PRMT3 with FAAH1. In the in vivo experiments, cisplatin was injected intraperitoneally at 6 mg/kg/day into C57BL/6 mice, and 7 days later, this study confirmed that PRMT3 and PRMT4 were upregulated in the organ of Corti of the mice. These results indicate that cisplatin-induced ototoxicity was correlated with PRMT3, PRMT4 and the cannabinoid system, and PRMT3 binding with FAAH1 was increased by cisplatin in HEI-OC1 cells. Therefore, this study suggests that PRMT3 mediates cisplatin-induced ototoxicity via interaction with FAAH1 in vitro and in vivo.

Ruthenium complex exerts antineoplastic effects that are mediated by oxidative stress without inducing toxicity in Walker-256 tumor-bearing rats

The present study evaluated the in vivo antitumor effects and toxicity of a new Ru(II) compound, cis-(Ru[phen]₂[ImH]₂)²⁺ (also called RuphenImH [RuC]), against Walker-256 carcinosarcoma in rats. After subcutaneous inoculation of Walker-256 cells in the right pelvic limb, male Wistar rats received 5 or 10mgkg^-1 RuC orally or intraperitoneally (i.p.) every 3 days for 13 days. A positive control group (2mgkg^-1 cisplatin) and negative control group (vehicle) were also used. Tumor progression was checked daily. After treatment, tumor weight, plasma biochemistry, hematology, oxidative stress, histology, and tumor cell respiration were evaluated. RuC was effective against tumors when administered i.p. but not orally. The highest i.p. dose of RuC (10mgkg^-1) significantly reduced tumor volume and weight, induced oxidative stress in tumor tissue, reduced the respiration of tumor cells, and induced necrosis but did not induce apoptosis in the tumor. No clinical signs of toxicity or death were observed in tumor-bearing or healthy rats that were treated with RuC. These results suggest that RuC has antitumor activity through the modulation of oxidative stress and impairment of oxidative phosphorylation, thus promoting Walker-256 cell death without causing systemic toxicity. These effects make RuC a promising anticancer drug for clinical evaluation.