Effects of polystyrene nano- and microplastics on human breast epithelial cells and human breast cancer cells

Abstract

The continuous littering of the environment with plastic and the resulting nano- and microplastics produced from various processes are ever-increasing problems. These materials also affect humans, as the absorption and accumulation of nano- and microplastics and their effects on health have thus far been rarely researched, which also applies to cancer. In the present study, the absorption of different sizes of polystyrene (PS) nano- and microplastics (PS particles) into human breast epithelial cells and human breast cancer cells was investigated. Subsequently, how the proliferation, colony and mammosphere formation abilities, cell fusion and migration of the cells were influenced by the PS particles were investigated. Our data revealed granularity-, dose- and cell line-dependent absorption of the PS particles, with the highest absorption observed in the MDA-MB-231-DSP1-7 cells and the lowest in the M13SV1_Syn1-DSP8-11 cells. Neither the colony-forming ability nor the cell fusion activity increased with the addition of PS particles. In contrast, slight, partially significant stimulatory effects on both proliferation and cell migration were observed, although these effects depended on the particle quantity and size and the cell line used. In summary, PS particles are absorbed by human breast epithelial and human breast cancer cells and influence cells that may be associated with cancer progression.

Keywords: Cancer stem cell properties; Cell fusion; Cell migration; Human breast cancer cells; Human breast epithelial cells; Polystyrene nano- and microplastics.

Fig. 1

Evaluation of particle absorption by M13SV1_Syn1-DSP8-11, HS578T-DSP1-7 and MDA-MB-231-DSP1-7 cells using flow cytometry. A) PS beads with sizes of 0.5 μm, B) 1.0 μm, and C) 4.5 μm. The flow cytometry data (means ± S.E.M.s) from three independent experiments are shown (n = 3). Statistical significance was determined using two-group ANOVA and Tukey's post hoc test: ∗p < 0.0332, ∗∗p < 0.0021, ∗∗∗p < 0.0002, and ∗∗∗∗p < 0.0001.

Fig. 2

Visualization of PS particle absorption by M13SV1_Syn1-DSP8-11, HS578T-DSP1-7 and MDA-MB-231-DSP1-7 cells via confocal laser scanning microscopy. Representative data from two independent experiments are shown. Computer-based 3D reconstructions of the 1.0 μm PS particles incorporated into M13SV1_Syn1-DSP8-11, HS578T-DSP1-7 and MDA-MB-231-DSP1-7 cells are provided in the Supplementary data.

Fig. 3

Relative sizes of M13SV1_Syn1-DSP8-11, HS578T-DSP1-7 and MDA-MB-231-DSP1-7 cells. The data are presented as the means ± S.E.M.s of three independent experiments. No significant differences were observed (one-way ANOVA and Tukey's post hoc test).

Fig. 4

Effect of PS particles on the proliferation of M13SV1_Syn1-DSP8-11, HS578T-DSP1-7 and MDA-MB-231-DSP1-7 cells. The data are presented as the means ± S.E.M.s of three independent experiments. No significant differences were observed (two-way ANOVA and Tukey's post hoc test).

Fig. 5

Effect of PS particles on the colony formation capacity of M13SV1_Syn1-DSP8-11, HS578T-DSP1-7 and MDA-MB-231-DSP1-7 cells. The data are presented as the means ± S.E.M.s of three independent experiments. No significant differences were observed (one-way ANOVA and Tukey's post hoc test).

Fig. 6

Effect of PS particles on the cell‒cell fusion of M13SV1_Syn1-DSP8-11 with HS578T-DSP1-7 cells and M13SV1_Syn1-DSP8-11 with MDA-MB-231-DSP1-7 cells. The data are presented as the means ± S.E.M.s of three independent experiments. Statistical significance was determined using two-group ANOVA and Tukey's post hoc test: ∗p < 0.0332, ∗∗p < 0.0021, ∗∗∗p < 0.0002, and ∗∗∗∗p < 0.0001.

Fig. 7

Effect of PS particles on the mammosphere formation capacity of M13SV1_Syn1-DSP8-11, HS578T-DSP1-7 and MDA-MB-231-DSP1-7 cells. The data are presented as the means ± S.E.M.s of three independent experiments. The data indicate that both the mean mammosphere count and size of MDA-MB-231-DSP1-7 breast cancer cells were slightly but not significantly increased by PS particles. No significant differences were observed (one-way ANOVA and Tukey's post hoc test).

Fig. 8

Effect of PS particles on the migration of M13SV1_Syn1-DSP8-11, HS578T-DSP1-7 and MDA-MB-231-DSP1-7 cells. The data are presented as the means ± S.E.M.s of three independent experiments. Statistical significance was determined using two-group ANOVA and Tukey's post hoc test: ∗p < 0.0332 and ∗∗p < 0.0021.