Figure 2.

Inhibition of exosome secretion decreased circSKA3 transfer

(A) Single-cell PCR showed that approximately 5%–10% cells (HIGH) expressed significantly higher levels of circSKA3 than other cells (LOW). Treatment with Cytochalasin D, Digoxin, or MβCD did not affect the average levels of circSKA3 in the cells but decreased cricSKA3 levels in the LOW cells and increased circSKA3 levels in the HIGH cells. Treatment with RNAse A only decreased cricSKA3 levels in the LOW cells relative to the medium control. (n = 80). (B) circSKA3-packed exosomes enhanced MCF-7 cell invasion (n = 4). (C) The invasion of MCF-7 cells was inhibited by RNAse A, Cytochalasin D, Digoxin, and MβCD (n = 4). (D) MCF-7 cells were cultured in a basal medium with 100 μg/mL control vector- or circSKA3-packed exosomes and processed to wound-healing assays for 3 days, showing that circSKA3-packed exosomes enhanced cell migration (n = 6). (E) MCF-7 cells were cultured in a basal medium with 100 μg/mL control vector- or circSKA3-packed exosomes for 3 days and processed to chamber migration assays with 100 μg/mL control vector- or circSKA3-packed exosomes at the bottom wells for 3 days. circSKA3-packed exosomes enhanced MCF-7 cell migration (n = 4). (F) Left, MCF-7 cells were cultured in a basal medium with 100 μg/mL control vector- or circSKA3-packed exosomes and chemicals RNAse A, Cytochalasin D, Digoxin, or MβCD for 3 days and processed to wound-healing assays. circSKA3-packed exosomes enhanced cell migration, which could be prevented by RNAse, Cytochalasin D, Digoxin, and MβCD. Right, in chamber migration assays, circSKA3-packed exosomes enhanced cell migration, which could be prevented by RNAse A, Cytochalasin D, Digoxin, and MβCD (n = 4), ∗ p<0.05; ∗∗ p<0.01; Error bars, SD.