Fig. 2

Membrane extracellular vesicles are dose-dependently transferred to sensitive cancer cells. A-B KB cells acquire moderate ABCB1 surface expression after co-incubating with EVs. C Representative confocol images show the involvement of contact-independent transfer in the intercellular transfer of ABCB1. KB cells are co-cultured with upper culture media isolated from resistant KBv200 cells (middle panel), or co-cultured with KBv cells but separated by a permeable membrane (1.0-μm pore size) to allow the traffic of secreted proteins but exclude direct cellular contact (lower panel). Red represents Cy3-ABCB1 and green represents GFP. D-E Representative confocol images show the increment of anchoring amount of ABCB1 to KB cells with the increasing EVs amount in co-cultured system. F The expression level of ABCB1 in KB cells is elevated with the increasing amount of EVs in co-cultures. G-H The accumulation of Rho123 in KB cells was reduced after incubation with EVs. I-J The co-incubation of KB cells with EVs from KBv200 cells dose-dependently endows sensitive KB cells with the ability to transport rhodamine 123. K The short-term exposure to 0.008 μM VCR results in a dominant plasma membrane localization of ABCB1 in recipient KB cells after cocultivation with equal amounts of EVs (80 μg/ml), as compared to untreated controls. L-M Flow cytometric analysis shows VCR resulted in an obvious concentration-dependent increase in the percentage of negative rhodamine 123 staining when KB cells are cocultured with equal EVs. Values are means ± SD. * = P < 0.05, ** = P < 0.01