Cytotoxic effects of cisplatin occur primarily through apoptosis. Though several pro- and anti-apoptotic signaling molecules have been identified to play an important role in mediating the ototoxic, nephrotoxic, and neurotoxic side-effects of cisplatin, the underlying mechanism is yet to be fully characterized. We reported that nitration of LIM domain only 4 (LMO4), a transcriptional regulator, facilitates cochlear apoptosis in cisplatin-induced ototoxicity. However, its role in cisplatin-mediated nephrotoxicity and neurotoxicity is poorly understood. Therefore, HK2, and SH-SY5Y cells were employed along with UBOC1 cells, to investigate the perturbations of LMO4 in cisplatin-induced cytotoxicity, in renal, neuronal, and auditory cells, respectively. Cisplatin induced an increase in the expression of active caspase-3, indicating cellular apoptosis, and increased the nitration of proteins, 24 h post-treatment. Immunostaining with anti-nitrotyrosine and anti-LMO4 indicated that nitrotyrosine co-localized with LMO4 protein in cisplatin treated cells. Immunoblotting with anti-LMO4 indicated that cisplatin induced a decrease in LMO4 protein levels. However, a corresponding decrease in LMO4 gene levels was not observed. Inhibition of protein nitration with SRI110, a peroxynitrite decomposition catalyst, attenuated cisplatin-induced downregulation of LMO4. More importantly, overexpression of LMO4 mitigated the cytotoxic effects of cisplatin in UBOC1 cells while a dose-dependent decrease in LMO4 protein strongly correlated with cell viability in UBOC1, HK2, and SH-SY5Y cells. Collectively, these findings suggested a potential role of LMO4 in facilitating the cytotoxic effects of cisplatin in auditory, renal, and neuronal cells.

中文翻译：

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顺铂诱导的听觉，肾和神经元细胞凋亡与LMO4的硝化和下调有关。

顺铂的细胞毒性作用主要通过细胞凋亡发生。尽管已经确定了几种促凋亡和抗凋亡信号分子在介导顺铂的耳毒性，肾毒性和神经毒性副作用中起着重要作用，但其潜在机制尚待充分表征。我们报告说，仅LIM域4（LMO4）的硝化，一种转录调节剂，促进顺铂诱导的耳毒性中的耳蜗凋亡。但是，人们对它在顺铂介导的肾毒性和神经毒性中的作用了解甚少。因此，HK2和SH-SY5Y细胞与UBOC1细胞一起被用于研究LMO4在顺铂诱导的细胞毒性中分别在肾，神经元和听觉细胞中的扰动。顺铂诱导了活性caspase-3表达的增加，表明细胞凋亡，处理后24小时增加了蛋白质的硝化作用。用抗硝基酪氨酸和抗LMO4免疫染色表明，在顺铂处理的细胞中，硝基酪氨酸与LMO4蛋白共定位。用抗LMO4进行的免疫印迹表明，顺铂诱导了LMO4蛋白水平的降低。但是，未观察到LMO4基因水平的相应下降。过氧亚硝酸盐分解催化剂SRI110抑制蛋白质硝化作用，减弱了顺铂诱导的LMO4的下调。更重要的是，LMO4的过表达减轻了UBOC1细胞中顺铂的细胞毒性作用，而LMO4蛋白的剂量依赖性降低与UBOC1，HK2和SH-SY5Y细胞的细胞活力密切相关。总的来说，