BACKGROUND: Different organs respond differently to cisplatin (CDDP)-induced toxicity. Oleuropein (OLE) is a natural phenolic antioxidant. The purpose of this study was to determine the potential protective effect of OLE against CDDP-induced ototoxicity by evaluating expression of genes associated with deoxyribonucleic acid (DNA) damage and repair in cochlear cells. METHODS: House Ear Institute-Organ of Corti 1 (HEI-OC1) cells were treated using CDDP, OLE, and OLE–CDDP. The water-soluble tetrazolium salt assay was used for monitoring cell viability. Deoxyribonucleic acid damage in cells due to the CDDP, OLE, and combination treatments was determined using a flow-cytometric kit. The change in the expression of 84 genes associated with CCDP, OLE, and OLE–CDDP treatments that induced DNA damage was tested using the reverse transcription polymerase chain reaction array. Changes ≥3-fold were considered significant. RESULTS: House Ear Institute-Organ of Corti 1 cell viability was significantly reduced by CDDP. The OLE–CDDP combination restored the cell viability. Cisplatin increased the H2AX ratio, while OLE–CDDP combination decreased it. Some of the DNA damage-associated genes whose expression was upregulated with CDDP were downregulated with OLE–CDDP, while the expression of genes such as Gadd45g and Rev1 was further downregulated. The expression of DNA repair-related Abl1, Dbd2, Rad52, and Trp53 genes was downregulated with CDDP, whereas their expression was upregulated with OLE–CDDP treatment. CONCLUSION: In cochlear cells, the OLE–CDDP combination downregulated DNA damage-associated gene expression relative to that upregulated mainly by CDDP. The results revealed that OLE has a potential protective effect on CDDP-induced ototoxicity in cochlear cells by altering the expression of DNA damage-related genes. Cite this article as: Olgun Y, Altun Z, Tütüncü M, Kum Özşengezer S, Aktaş S, Güneri EA. The impact of oleuropein on cisplatin-induced toxicity in cochlear cells in relation to the expression of deoxyribonucleic acid damage-associated genes. J Int Adv Otol. 2024;20(3):189-195.

Objectives: Neuroblastoma is the most common extracranial solid tumor in childhood. YAP (Yes‐associated protein) is a highly expressed protein in NB. Nestin is an important marker of neuronal differentiation in NB. Orthodenticle homeobox (OTX) is a transcription factor and is overexpressed in blastoma‐derived tumors. The aim of this study was to examine the potential roles of YAP‐1, Nestin, and OTX‐2 proteins in prognosis and risk stratification in neuroblastomaMethods: Tumor sections of 56 patients with different NB risk groups were analyzed. YAP‐1, Nestin, and OTX‐2 protein expression levels were evaluated by immunohistochemical staining in NB patient tissue samples.Results: YAP‐1, Nestin, and OTX‐2 protein expression levels were evaluated together with the clinical findings of NB patients. YAP‐1 was expressed in 18% of all tissues, while Nestin was expressed in 20.4%. OTX‐2 protein expression was found in 41.1% of the NB patients. YAP‐1 was expressed in 26.9% of high‐risk and 11.5% of low‐risk patients. Nestin was expressed in 24.4% high‐risk and 33.3% low‐risk patients. OTX‐2 was expressed in 68.2% high‐risk and 60% low‐risk patients.YAP‐1 was shown to provide survival advantages among risk groups.Interpretation: The findings of this study support that YAP‐1 may be a potential prognostic biomarker for staging and risk‐group assignment of NB patients. YAP‐1 expression in neuroblastoma is associated with significantly poorer survival probabilities and should be considered as a potential therapeutic target. OTX‐2 is a promising predictive biomarker candidate, but its mechanisms need further investigation in neuroblastoma, as nestin expression is not significantly linked to patient survival.

Ovarian cancer (OC) accounts for a significant percentage of cancer-related deaths in women worldwide. A small proportion of ovarian cancers, usually in women under 40, originate from germ cells and stromal cells within the ovary, but the vast majority are epithelial malignancies. The preferred treatment for ovarian malignancies consists of platinum-based chemotherapy and surgical intervention. Chemoresistance in ovarian cancer is a complex problem that significantly impedes tratment efficacy. Many pathways contribute to this resistance, including genetic factors, tumor microenvironment interactions, and lifestyle variables such as obesity. Understanding these mechanisms is crucial for developing effective treatment solutions. The circadian rhythm, or circadian clock, regulates the sleep–wake cycle, body temperature, hormone secretion, metabolism, and many physiological processes. Circadian genes are highly expressed in the ovaries, which regulate ovulation. Disruption of circadian rhythm asociated with many risk factors for ovarian cancer. This article examines the relationship between circadian rhythm and chemotherapy resistance in ovarian cancer, and reviews circadian rhythm to reduce chemotherapy resistance in this context.

Amaç: Darbepoetin-alfa (DPO) uygulamasının sisplatine bağlı ototoksik etkiyi önleyici rolü olup olmadığının in-vivo olarak değerlendirilmesi amaçlandı. Materyal metod: Çalışmada 28 adet wistar albino rat kullanılarak 4 grup oluşturuldu. Grup 1 (intraperitoneal) IP salin verilen kontrol grubu, Grup 2 sisplatin (16mg/kg IP tek doz), Grup 3 DPO (25 μg/kg IP), Grup 4 sisplatin verilmeden 24 saat önce ve verildikten yarım saat sonra 25 μg/kg tek doz IP DPO uygulanan grup. Ratlara ajan uygulamalarından önce ve deneyin 7. gününde distorsiyon ürünü otoakustik emisyon (DPOAE) ve işitsel uyarılmış beyin sapı potansiyelleri (ABR) yapıldı. İşitme ölçümleri sonrasında ratlar sakrifiye edildi. Apoptotik hücre ölümü kulak dokusunda kaspaz-3, -8, -9 ve Nrf2 ve Hem oksijenaz-1 (HO-1), NQQ1, Glutatyon (GST) gibi Nrf2 ilişkili antioksidan ve iNOS, nNOS ekspresyon düzeyleri immünohistokimyasal yöntemle çalışıldı. Serum glutatyon (GSH) ve anti-inflamatuar TNF-α ve IL-1 protein düzeyleri ELISA kitleri kullanılarak belirlendi. Bulgular: Sisplatin uygulaması ile işitme ölçümlerinde kontrole göre ototoksik etkileri gösteren tüm frekanslarda işitme kaybı saptandı. İmmunohistokimyasal doku düzeyinde gerçekleştirilen incelemelerde sisplatin uygulanan grupta iç kulakta strüktürel değişiklikler, beyin ve sinir dokularında nekroz ve nekroptoz saptandı. Darbepoetinin sisplatinin ortaya çıkardığı iç kulak ve beyin hasarlarını önleyici etkileri hem apoptotik protein ekspresyonları hem de oksidatif stres ile ilişkili belirteçler olan Nrf-2 ve ilişkili HO-1, NQO1, iNOS ve nNOS, GST ve anti-inflamatuar proteinleri üzerinden saptandı. Sonuç: Bu çalışmada sisplatinin oluşturduğu ototoksisitede DPO’in koruyucu etkileri apoptozun azaltılması, antioksidan Nrf-2 ve hedef proteinler ve glutatyon düzeylerinin artışı yanında anti-inflamatuar proteinler üzerinden geliştiği gösterilmiştir.