Carcinogenic activity of PbS quantum dots screened using exosomal biomarkers secreted from HEK293 cells

Abstract

Lead sulfide (PbS) quantum dots (QDs) have been applied in the biomedical area because they offer an excellent platform for theragnostic applications. In order to comprehensively evaluate the biocompatibility of PbS QDs in human cells, we analyzed the exosomes secreted from cells because exosomes are released during cellular stress to convey signals to other cells and serve as a reservoir of enriched biomarkers. PbS QDs were synthesized and coated with 3-mercaptopropionic acid (MPA) to allow the particles to disperse in water. Exosomes were isolated from HEK293 cells treated with PbS–MPA at concentrations of 0 µg/mL, 5 µg/mL, and 50 µg/mL, and the exosomal expression levels of miRNAs and proteins were analyzed. As a result, five miRNAs and two proteins were proposed as specific exosomal biomarkers for the exposure of HEK293 cells to PbS–MPA. Based on the pathway analysis, the molecular signature of the exosomes suggested that PbS–MPA QDs had carcinogenic activity. The comet assay and expression of molecular markers, such as p53, interleukin (IL)-8, and C-X-C motif chemokine 5, indicated that DNA damage occurred in HEK293 cells following PbS–MPA exposure, which supported the carcinogenic activity of the particles. In addition, there was obvious intensification of miRNA expression signals in the exosomes compared with that of the parent cells, which suggested that exosomal biomarkers could be detected more sensitively than those of whole cellular extracts.

Keywords:

• comet assay
• DNA damage
• exosome
• high-throughput screening
• lead sulfide quantum dots (PbS QDs)
• nanoparticle toxicity

Supplementary materials

Figure S1 Selected protein spots for PMF analysis according to selection criteria.

Notes: (A) Nineteen spots were increased and (B) ten spots were decreased by exposure to PbS–MPA QDs.

Abbreviations: PMF, peptide map fingerprint; PbS–MPA QDs, lead sulfide–3-mercaptopropionic acid quantum dots.

Table S1 Functional analysis of miRNA biomarkers by ingenuity pathway analysis (IPA) analysis

Acknowledgments

This study was supported in part by the Ministry of Science, ICT, and Future Planning of the Republic of Korea (DGIST Basic Research Fund 15-NB-01 and 15-BD-0404). This research was supported also by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT, and Future Planning (NRF-2013R1A1A1008678). We are thankful to the DGIST Center for Core Research Facilities for providing aid with the TEM and XRD experiments. We also are thankful to the Korea Basic Science Institute (KBSI) for providing technical assistance on the operation of Bio-TEM and the Ultra microtome.

Disclosure

The authors report no conflicts of interest in this work.