Effects of As2O3 nanoparticles on cell growth and apoptosis of NB4 cells

Abstract

The aim of the present study was to explore the preparation of arsenic trioxide (As₂O₃) nanoparticles and examine the antitumor effects of these nanoparticles on NB4 cells. As₂O₃ nanoparticles were prepared using the sol-gel method and characterized using transmission electron microscopy and energy dispersive spectroscopy. The results indicated that the As₂O₃ nanoparticles prepared in the present study were round or elliptical, well dispersed and had an ~40-nm or <10-nm diameter. The antitumor effects of As₂O₃ nanoparticles at various concentrations were analyzed by flow cytometry and the MTT assay, and were compared with those of traditional As₂O₃ solution. At the same concentration and incubation time (48 h), the survival rate of cells treated with As₂O₃ nanoparticles was significantly lower than that of cells treated with the As₂O₃ solution. The growth inhibition rate under both treatments was time- and dose-dependent. In addition, at the same concentration and incubation time, the apoptosis rate of the cells treated with As₂O₃ nanoparticles was significantly higher than that of the cells treated with the As₂O₃ solution. Furthermore, As₂O₃ nanoparticles resulted in a greater reduction in the expression of the anti-apoptotic protein B-cell lymphoma 2 compared with the As₂O₃ solution. In conclusion, As₂O₃ nanoparticles, prepared using the sol-gel method, were found to produce a stronger cytotoxic effect on tumor cells than that produced by the As₂O₃ solution, possibly by inhibiting Bcl-2 expression.

Keywords: NB4 cells; apoptosis; arsenic trioxide; growth inhibition; nanotechnology.

Figure 1.

Morphology of As₂O₃ powder and nanoparticles. (A) As₂O₃ powder under scanning electron microscopy (magnification, ×10,000); (B) As₂O₃ nanoparticles (<10 nm) under transmission electron microscopy (magnification, ×300,000). As₂O₃, arsenic trioxide.

Figure 2.

Energy dispersive spectrometry results of (A) As₂O₃ powder and (B) As₂O₃ nanoparticles. As₂O₃, arsenic trioxide.

Figure 3.

Optical inverted microscopy images of NB4 cells incubated with As₂O₃ solution or As₂O₃ nanoparticles for 48 h (magnification, ×40). NB4 cells were treated as follows: (A) Control, (B) As₂O₃ solution (1.5 µmol/l), (C) As₂O₃ nanoparticles (1.5 µmol/l), (D) As₂O₃ solution (3.0 µmol/l) and (E) As₂O₃ nanoparticles (3.0 µmol/l). As₂O₃, arsenic trioxide.

Figure 4.

Comparison between the growth-inhibition effects of As₂O₃ solution and nanoparticles. The growth-inhibition effects of As₂O₃ solution and nanoparticles on NB4 cells were compared at different incubation time-points (24, 48, 72 and 96 h). Growth-inhibitory effects of (A) As₂O₃ solution and (B) As₂O₃ nanoparticles. (C) Following the treatment of NB4 cells with As₂O₃ solution or nanoparticles for 48 h at different concentrations, the growth-inhibitory effects were compared. As₂O₃, arsenic trioxide.

Figure 5.

Apoptosis of NB4 cells 48 h after treatment with As₂O₃ solution or As₂O₃ nanoparticles. NB4 cells were treated as follows (the percentage of apoptotic cells is indicated): (A) Control, 0.86%; (B) As₂O₃ solution (1.5 µmol/l), 8.60%; (C) As₂O₃ nanoparticles (1.5 µmol/l), 10.44%; (D) As₂O₃ solution (3.0 µmol/l), 10.34%; (E) As₂O₃ nanoparticles (3.0 µmol/l), 23.41%. As₂O₃, arsenic trioxide; PI, propidium iodide; FITC, fluorescein isothiocyanate.

Figure 6.

Bcl-2 expression of NB4 cells following treatment with As₂O₃ solution or As₂O₃ nanoparticles for 48 h. NB4 cells were treated as follows: 1, Control; 2, As₂O₃ solution (1.5 µmol/l); 3, As₂O₃ nanoparticles (1.5 µmol/l); 4, As₂O₃ solution (3.0 µmol/l); 5, As₂O₃ nanoparticles (3.0 µmol/l). As₂O₃, arsenic trioxide; Bcl-2, B-cell lymphoma 2.