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Objectives To investigate behaviour and expression of transforming growth factor-β (TGF-β) and matrix metalloproteinases (MMP-9) in murine photoreceptor-derived cells (661W) after incubation with zinc oxide (ZnO) nanoparticles. Materials and methods We explored effects of ZnO nanoparticles on 661W cells using a real-time cell electronic sensing system, flow cytometry, multiple function microplate reading, real-time quantitative PCR detection system and enzyme-linked immunosorbent assay respectively. Results Our results indicate that ZnO nanoparticles induced overload of calcium and reactive oxygen species within cells, causing formation of apoptotic bodies, disruption of cell cycle distribution, and reduction in expression of TGF-β and MMP-9, to suppress cell proliferation and migration. Our findings show that disruption of intracellular calcium homoeostasis and overproduction of reactive oxygen species were closely associated with reduction of TGF-β and MMP-9 in 661W cells under ZnO nanoparticle treatment. Conclusions Results of our study indicate that ZnO nanoparticles suppressed cell proliferation and migration, and reduced production of TGF-β and MMP-9 at both gene and protein levels. Our findings contribute to the understanding of the molecular mechanisms that reduced TGF-β and MMP-9 levels inhibit cell proliferation and migration under ZnO nanoparticle influence.

Objectives As a parenchymal cell, the photoreceptor is more susceptible to alterations in outer micro-environmental conditions than other cells. In the present study, we aimed to investigate inhibitory effects of zinc oxide (ZnO) nanoparticles on expression of manganese superoxide dismutase (MnSOD) in murine photoreceptor-derived cells. Materials and methods We investigated effects of ZnO nanoparticles on murine photoreceptor cell viability and on expression and activity of MnSOD using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay, immunofluorescence analysis, flow cytometry, quantitative real-time PCR and enzyme-linked immunosorbent assay (ELISA). Results ZnO nanoparticles were found to have higher cytotoxic effects in concentration- and time-dependent manners, to elevate intracellular levels of hydrogen peroxide and hydroxyl radicals, and thus to induce overproduction of reactive oxygen species (ROS) and collapse of mitochondrial membrane potential, leading to cell damage. Moreover, ZnO nanoparticles also significantly reduced expression of MnSOD at both the mRNA and protein levels, reduced its activity, and further aggravated oxidative stress-mediated cell damage. Conclusion Overall, ZnO nanoparticle-induced cytotoxicity was associated with elevated levels of oxidative stress due to overproduction of ROS and reduced expression and activity of MnSOD.