Acceleration of cisplatin ototoxicity by perilymphatic application of 4-methylthiobenzoic acid

Chemotherapy Side-Effects: Not All DNA Damage Is Equal

Recent advances have increased survival rates of children and adults suffering from cancer thanks to effective anti-cancer therapy, such as chemotherapy. However, during treatment and later in life they are frequently confronted with the severe negative side-effects of their life-saving treatment. The occurrence of numerous features of accelerated aging, seriously affecting quality of life, has now become one of the most pressing problems associated with (pediatric) cancer treatment. Chemotherapies frequently target and damage the DNA, causing mutations or genome instability, a major hallmark of both cancer and aging. However, there are numerous types of chemotherapeutic drugs that are genotoxic and interfere with DNA metabolism in different ways, each with their own biodistribution, kinetics, and biological fate. Depending on the type of DNA lesion produced (e.g., interference with DNA replication or RNA transcription), the organ or cell type inflicted (e.g., cell cycle or differentiation status, metabolic state, activity of clearance and detoxification mechanisms, the cellular condition or micro-environment), and the degree of exposure, outcomes of cancer treatment can largely differ. These considerations provide a conceptual framework in which different classes of chemotherapeutics contribute to the development of toxicities and accelerated aging of different organ systems. Here, we summarize frequently observed side-effects in (pediatric) ex-cancer patients and discuss which types of DNA damage might be responsible.

Effect of Remote Ischemic Preconditioning on Systemic Toxicity and Ototoxicity Induced by Cisplatin in Rats: Role of TNF-α and Nitric Oxide

BACKGROUND/AIMS

Cisplatin is a chemotherapeutic agent. The use of remote ischemic preconditioning (RIPC) was proposed after the observation that ischemic preconditioning of a cardiac vascular area could protect another completely distinctly.

METHODS

This is an experimental study. Male Wistar rats were anesthetized, and they underwent a hearing evaluation via measurement of the brainstem auditory evoked potential (BSAEP). Then, cisplatin was administered intraperitoneally (IP) at a dose of 8 mg/kg/day for 4 consecutive days to group 1, whereas saline solution was administered IP to group 2. In groups 3 and 4, ischemia of the right hind paw was performed for 10 min, followed by reperfusion for 30 min, after which cisplatin or saline was administered IP to group 3 or group 4, respectively. Afterwards, all animals were evaluated via the BSAEP. The right cochlea was dissected for immunohistochemistry.

RESULTS

RIPC lowered the increase in BSAEP of the animals treated with cisplatin (p = 0.0146). Weight loss decreased in the animals subjected to RIPC (p < 0.005). In group 3, RIPC reversed immunostaining for tumor necrosis factor-α and inducible nitric oxide synthase in the stria vascularis injured by cisplatin (p < 0.05).

CONCLUSION

RIPC protects against systemic toxicity and ototoxicity induced by cisplatin in rats.

Effectiveness of different approaches for establishing cisplatin-induced cochlear lesions in mice

CONCLUSIONS

Mouse cochleae are highly resistant to systemically administered cisplatin. However, cochlear lesions can be produced effectively in mice when cisplatin is applied locally through the round window niche or tympanum.

OBJECTIVE

To explore the optimal approach for creating cisplatin-induced cochlear lesions in mice.

MATERIALS AND METHODS

Cisplatin was administered to adult C57BL/6J mice via four approaches: (1) transtympanic injection, (2) round window niche injection, (3) intraperitoneal injection (i.p.) at 4 mg/kg/day for 4 consecutive days, and (4) one 15 mg/kg dose i.p. The hearing was monitored using frequency-specific auditory brainstem responses (ABRs) and distortion-product otoacoustic emissions (DPOAEs). Cochlear pathology was observed in cochleograms with Harris' hematoxylin staining.

RESULTS

Cisplatin applied systemically did not cause any significant ABR threshold elevation across the frequencies tested (2-32 kHz), whereas local application of cisplatin through the round window niche or tympanum resulted in significant ABR threshold elevations from high to medium frequencies. The functional changes were consistent with the cochlear pathology across groups.