Enhancement Of Autophagy Of Bladder Tumor By Microcapsules Of Human Umbilical Cord Mesenchymal Stem Cells Induced By AKT / MTOR Signaling Pathway

Objective:Microvesicles(MVs) derived from Human Umbilical Cord Mesenchymal Stem Cells(h WJMSCs) are small membrane vesicles, which are considered as a novel avenue intercellular communication. h WJMSC-MVs can inhibit bladder tumor T24 cells growth in vitro and in vivo.Methods:we investigated the effects of MVs derived from h WJMSCs on autophagy in T24 cells. h WJMSC-MVs-treated T24 cells displayed autophagic features, such as protein expression levels of autophagy related protein Beclin 1, Atg5-Atg12 were assayed by quantitative Western blot and autophagic vacuoles were examined by transmission electron microscopy respectively. To study the conceivable mechanism that h WJMSC-MVs upregulated autophagy of bladder tumor T24 cells, we estimated the expression of Akt/phosphor-Akt(p-Akt), m TOR/phosphor-m TOR(p-m TOR)by Western blot after exposing T24 cells to h WJMSC-MVs. Furthermore, Pretreatment of cells with 3-methyladenine(an inhibitor of class III phosphatidylinositol-3 kinase; 3-MA)suppressed h WJMSC-MVs mediated antiproliferation activity, suggesting that induction of autophagy by h WJMSC-MVs reduced the effect of h WJMSC-MVs on apoptosis of T24 cells. T24 cells apoptosis were assessed by Annexin V/PI staining.Results: After T24 cells were treated with h WJMSC-MVs(0, 200μg/ml protein) for 48 h,Expression of autophagy-related proteins Beclin 1, Atg5-Atg12 were up-regulated and the Akt/m TOR signaling pathway in h WJMSC-MVs-treated T24 cells were down-regulated.The autophagic vacuoles examined by transmission electron microscopy were increased. Furthermore, Pretreatment of cells with 3-MA suppressed h WJMSC-MVs mediated antiproliferation activity and T24 cells apoptosis were assessed by Annexin V/PI staining, the result show that induction of autophagy by h WJMSC-MVs reduced the effect of h WJMSC-MVs on apoptosis of T24 cells.Conclusion: Our data indicated showed that h WJMSC-MVs-induced autophagy was promoted by decreases p-AKT and p-m TOR levels and finally suppressed apoptotic cell death in bladder tumor. In the near future, MVs derived from Human Umbilical Cord Mesenchymal Stem Cells might become a novel anti-tumor medicine in the clinic.