title: Cisplatin-induced apoptosis in auditory, renal, and neuronal cells is associated with nitration and downregulation of LMO4.
abstract: 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.
authors.affiliation: Institute of Environmental Health Sciences, Wayne State University, Detroit, Michigan, USA - 48202.
authors.forename: Rajamani
authors.initials: R
authors.lastname: Rathinam
authors.affiliation: Department of Family Medicine and Public Health Sciences, Wayne State University, Detroit, Michigan, USA - 48201.
authors.forename: Samiran
authors.initials: S
authors.lastname: Ghosh
authors.affiliation: Department of Pharmaceutical Sciences, Southern Illinois University Edwardsville, Edwardsville, IL, USA - 62026.
authors.forename: William L
authors.initials: WL
authors.lastname: Neumann
authors.affiliation: Institute of Environmental Health Sciences, Wayne State University, Detroit, Michigan, USA - 48202; Department of Family Medicine and Public Health Sciences, Wayne State University, Detroit, Michigan, USA - 48201.
authors.forename: Samson
authors.initials: S
authors.lastname: Jamesdaniel
keywords: LMO4; apoptosis; cell viability; cisplatin; nitration; ototoxicity