DJ-1 as a potential biomarker for the development of biocompatible multiwalled carbon nanotubes

Abstract

Hisao Haniu1, Tamotsu Tsukahara2, Yoshikazu Matsuda3, Yuki Usui4, Kaoru Aoki5, Masayuki Shimizu5, Nobuhide Ogihara5, Kazuo Hara5, Seiji Takanashi5, Masanori Okamoto5, Norio Ishigaki5, Koichi Nakamura5, Hiroyuki Kato5, Naoto Saito6 1Institute of Carbon Science and Technology, 2Department of Integrative Physiology and Bio-System Control, Shinshu University, Matsumoto, Nagano, 3Clinical Pharmacology Educational Center, Nihon Pharmaceutical University, Ina-machi, Saitama, 4Research Center for Exotic Nanocarbons, 5Department of Orthopaedic Surgery, 6Department of Applied Physical Therapy, Shinshu University School of Health Sciences, Shinshu University, Matsumoto, Nagano, Japan Background: In the present study, we investigated whether DJ-1 could serve as a biomarker for assessing the biocompatibility of multiwalled carbon nanotubes (MWCNTs), using the highly purified carbon nanotube, HTT2800. Methods: Using Western blot analysis, we determined DJ-1 protein levels in two different types of cells (one capable and the other incapable of HTT2800 endocytosis). Using quantitative real-time polymerase chain reaction, we also investigated the ability of purified nanotubes to alter DJ-1 mRNA levels. Results: We demonstrated that the DJ-1 protein concentration was reduced, regardless of the cytotoxic activity of intracellular HTT2800. Furthermore, HTT2800 decreased the DJ-1 mRNA levels in a dose-dependent manner. This decrease in DJ-1 mRNA levels was not observed in the case of Sumi black or cup-stacked carbon nanotubes. Conclusion: These data indicate that modification of DJ-1 expression is caused by the cell response to MWCNTs. We conclude that DJ-1 is a promising candidate biomarker for the development of biocompatible MWCNTs. Keywords: multiwalled carbon nanotubes, DJ-1 protein, Western blot, quantitative real-time polymerase chain reaction