International Journal of Nanomedicine (Mar 2020)
Anticancer Effects of Zinc Oxide Nanoparticles Through Altering the Methylation Status of Histone on Bladder Cancer Cells
Abstract
Tianke Zhang,1,2 E Du,1 Yan Liu,1 Jun Cheng,2 Zhihong Zhang,1 Yong Xu,1 Shiyong Qi,1 Yue Chen1 1Department of Urology, The Second Hospital of Tianjin Medical University, Tianjin Institute of Urology, Tianjin 300211, People’s Republic of China; 2Department of Anorectal Surgery, Tianjin Union Medical Center, Tianjin 300121, People’s Republic of ChinaCorrespondence: Yue Chen; Shiyong QiDepartment of Urology, The Second Hospital of Tianjin Medical University, Tianjin Institute of Urology, No. 23, Pingjiang Road, Hexi District, Tianjin 300211 Tel +86-18630913339; +86-022-88329692Email [email protected]; [email protected]: Zinc oxide nanoparticles (nZnO) have been widely used in the medicine field. Numerous mechanistic studies for nZnO’s anticancer effects are merely performed under high concentration exposure. However, possible anticancer mechanisms of epigenetic dysregulation induced by low doses of nZnO are unclear.Methods: nZnO were characterized and bladder cancer T24 cells were treated with nZnO for 48 hrs at different exposure concentrations. Cell cycle, apoptosis, cell migration and invasion were determined. We performed qRT-PCR, Western blot and chromatin immunoprecipitation to detect the mRNA and protein levels of signaling pathway cascades for histone modification.Results: In this study, we investigated the potential anticancer effects and mechanisms of nZnO on histone modifications in bladder cancer T24 cells upon low-dose exposure. Our findings showed that low concentrations of nZnO resulted in cell cycle arrest at S phase, facilitated cellular late apoptosis, repressed cell invasion and migration after 48 hrs exposure. These anticancer effects could be attributed to increased RUNX3 levels resulting from reduced H3K27me3 occupancy on the RUNX3 promoter, as well as decreased contents of histone methyltransferase EZH2 and the trimethylation of histone H3K27. Our findings reveal that nZnO are able to enter into the cytoplasm and nucleus of T24 cells. Additionally, both particles and ions from nZnO may jointly contribute to the alteration of histone methylation. Moreover, sublethal nZnO-conducted anticancer effects and epigenetic mechanisms were not associated with oxidative stress or DNA damage.Conclusion: We reveal a novel epigenetic mechanism for anticancer effects of nZnO in bladder cancer cells under low-dose exposure. This study will provide experimental basis for the toxicology and cancer therapy of nanomaterials.Keywords: zinc oxide nanoparticles, epigenetics, histone modification, methylation, EZH2, RUNX3
