The effect of genistein on cisplatin induced ototoxicity and oxidative stress

Ototoxicity among cisplatin, carboplatin, and oxaliplatin in zebrafish model

Platinum-based antineoplastic drugs, including cisplatin, carboplatin, and oxaliplatin, are widely used in the treatment of various cancers. Ototoxicity is a common adverse effect of platinum-based drugs. Ototoxicity leads to irreversible hearing impairment. We hypothesize that different platinum-based drugs exhibit varying ototoxic concentrations, time effects, and ototoxic mechanisms. We tested this hypothesis by using a zebrafish model (pvalb3b: TagGFP) to assess the viability of hair cells collected from zebrafish larvae. Cisplatin, carboplatin, and oxaliplatin were administered at dosages of 100, 200, or 400 μM, and the ototoxic effects of these drugs were assessed 1, 2, or 3 h after administration. Fm4-64 and a TUNEL assay were used to label the membranes of living hair cells and to detect cell apoptosis, respectively. We observed that >50% of hair cells were damaged at 1 h after cisplatin (100 μM) exposure, and this ototoxic effect increased at higher dosages and over time. Owing to the smaller ototoxic effects of carboplatin and oxaliplatin, we conducted higher-strength and longer-duration experiments with these drugs. Neither carboplatin nor oxaliplatin was obviously ototoxic, even at 1600 μM and after 6 h. Moreover, only cisplatin damaged the membranes of the hair cells. Cell apoptosis and significantly increased antioxidant gene expression were observed in only the cisplatin group. In conclusion, cisplatin significantly damages sensory hair cells and has notable dosage and time effects. Carboplatin and oxaliplatin are less ototoxic than cisplatin, likely due to having different ototoxic mechanisms than cisplatin.

Drug screening identifies aldose reductase as a novel target for treating cisplatin-induced hearing loss

Cisplatin is a frequently used chemotherapeutic medicine for cancer treatment. Permanent hearing loss is one of the most serious side effects of cisplatin, but there are few FDA-approved medicines to prevent it. We applied high-through screening and target fishing and identified aldose reductase, a key enzyme of the polyol pathway, as a novel target for treating cisplatin ototoxicity. Cisplatin treatment significantly increased the expression level and enzyme activity of aldose reductase in the cochlear sensory epithelium. Genetic knockdown or pharmacological inhibition of aldose reductase showed a significant protective effect on cochlear hair cells. Cisplatin-induced overactivation of aldose reductase led to the decrease of NADPH/NADP+ and GSH/GSSG ratios, as well as the increase of oxidative stress, and contributed to hair cell death. Results of target prediction, molecular docking, and enzyme activity detection further identified that Tiliroside was an effective inhibitor of aldose reductase. Tiliroside was proven to inhibit the enzymatic activity of aldose reductase via competitively interfering with the substrate-binding region. Both Tiliroside and another clinically approved aldose reductase inhibitor, Epalrestat, inhibited cisplatin-induced oxidative stress and subsequent cell death and thus protected hearing function. These findings discovered the role of aldose reductase in the pathogenesis of cisplatin-induced deafness and identified aldose reductase as a new target for the prevention and treatment of hearing loss.

Effects of natural products on cisplatin ototoxicity and chemotherapeutic efficacy

INTRODUCTION

Cisplatin is a very effective chemotherapeutic agent against a variety of solid tumors. Unfortunately, cisplatin causes permanent sensorineural hearing loss in at least two-thirds of patients treated. There are no FDA approved drugs to prevent this serious side effect.

AREAS COVERED

This paper reviews various natural products that ameliorate cisplatin ototoxicity. These compounds are strong antioxidants and anti-inflammatory agents. This review includes mostly preclinical studies but also discusses a few small clinical trials with natural products to minimize hearing loss from cisplatin chemotherapy in patients. The interactions of natural products with cisplatin in tumor-bearing animal models are highlighted. A number of natural products did not interfere with cisplatin anti-tumor efficacy and some agents actually potentiated cisplatin anti-tumor activity.

EXPERT OPINION

There are a number of natural products or their derivatives that show excellent protection against cisplatin ototoxicity in preclinical studies. There is a need to insure uniform standards for purity of drugs derived from natural sources and to ensure adequate pharmacokinetics and safety of these products. Natural products that protect against cisplatin ototoxicity and augment cisplatin's anti-tumor effects in multiple studies of tumor-bearing animals are most promising for advancement to clinical trials. The most promising natural products include honokiol, sulforaphane, and thymoquinone.

Pro-Inflammatory Signalling PRRopels Cisplatin-Induced Toxicity

Cisplatin is a platinum-based chemotherapeutic that has long since been effective against a variety of solid-cancers, substantially improving the five-year survival rates for cancer patients. Its use has also historically been limited by its adverse drug reactions, or cisplatin-induced toxicities (CITs). Of these reactions, cisplatin-induced nephrotoxicity (CIN), cisplatin-induced peripheral neuropathy (CIPN), and cisplatin-induced ototoxicity (CIO) are the three most common of several CITs recognised thus far. While the anti-cancer activity of cisplatin is well understood, the mechanisms driving its toxicities have only begun to be defined. Most of the literature pertains to damage caused by oxidative stress that occurs downstream of cisplatin treatment, but recent evidence suggests that the instigator of CIT development is inflammation. Cisplatin has been shown to induce pro-inflammatory signalling in CIN, CIPN, and CIO, all of which are associated with persisting markers of inflammation, particularly from the innate immune system. This review covered the hallmarks of inflammation common and distinct between different CITs, the role of innate immune components in development of CITs, as well as current treatments targeting pro-inflammatory signalling pathways to conserve the use of cisplatin in chemotherapy and improve long-term health outcomes of cancer patients.