Fig. 1

The number, size, and morphology of extracellular vesicles emitted by trastuzumab-sensitive and trastuzumab-resistant breast tumor cells are similar to each other and are not affected by trastuzumab. a, b Human breast cancer cells BT-474 (a) or their variant BT-474TR (b) were allowed to form colonies in soft agar in the absence (−) or in the presence (+) of 5 μg/ml trastuzumab (TZ). The colonies were counted 3 weeks later. The data represent the average of three independent experiments plus the SE.*p < 0.05. c BT-474 and BT-474TR cells were treated (+TZ) or not with 5 μg/ml trastuzumab in 3D culture for 72 h. The analysis of the nanoparticle size distribution in the cell media was performed by the use of the NS500 Nanoparticle Tracking Analysis system. The data represent the average of 3 independent experiments plus SD. Nanoparticle size distribution did not show a statistically significant difference between BT-474 and BT-474TR cells nor between trastuzumab-treated and untreated cells in the case of both cell lines. d BT-474 and BT-474TR cells were treated (+TZ) or not with 5 μg/ml trastuzumab in 3D culture for 72 h, and EVs were isolated from the cell media by ultracentrifugation and analyzed by transmission electron microscopy