Fig. 8

TEMo-secreted miR-181a activates AKT signaling partly by inhibiting PTEN in BC cells. A Western blot analysis showed up-regulation of the phosphorylated levels of AKT and mTOR in MDA-MB-231 BC cells, 48 h after treatment with 100 μg/mL TEMo-Exo compared with the corresponding control cells. Results indicated that the promoting effects of TEMo-Exo on Akt–mTOR signaling were partially abolished when the cells were transfected with the miR-181a inhibitor. B Western blot analysis revealed that when MDA-MB-231 BC cells were incubated with the AKT inhibitor MK-2206, the activation of the Akt–mTOR signaling caused by miR-181a was suppressed. Actin was used as an endogenous loading control. Western blot images are representative of at least three independent experiments. C BC cells displayed the lowest rate of proliferation when treated with MK-2206 at the indicated time points. Although transfection of miR-181a mimic considerably increased the proliferation rate of MDA-MB-231 BC cells compared to control cells, miR-181a did not increase BC cell proliferation in the cell group treated with MK-2206. Points, mean of three different experiments; bars, SD. **P-value < 0.01. D, E Representative photomicrographs (D) and bar graphs (E) illustrated that MK-2206 abrogated the promoting effect of miR-181a on BC cell migration. F Transfection of miR-181a mimic caused a significant reduction of PTEN expression at both mRNA and protein levels in MDA-MB-231 BC cells, suggesting that miR-181a may regulate PTEN in BC cells. G The mean normalized ratio for PTEN mRNA levels were measured by RT-qPCR in different conditions, 48 h after incubation. Results demonstrated that PTEN mRNA levels were considerably decreased in MDA-MB-231 BC cells incubated with 100 μg/mL TEMo-Exo compared to those cells incubated with exosomes derived from control monocytes or NEMo. In contrast, inhibition of miR-181a in MDA-MB-231 BC cells partially prevented the inhibitory effect of TEMo-Exo on PTEN expression. Columns, mean of three different experiments; bars, SD. *P-value < 0.05, **P-value < 0.01, ***P-value < 0.001