Human urine extract CDA-2 induces apoptosis of myelodysplastic syndrome-derived MUTZ-1 cells through the PI3K/Akt signaling pathway in a caspase-3-dependent manner.

AIM: The aim of this study was to investigate the antitumoral activity of human urine extract against myelodysplastic syndrome (MDS)-derived MUTZ-1 cells in vitro and in vivo.

METHODS

The MDS-refractory anemia with excess of blasts (RAEB)-derived MUTZ-1 cell line was used to examine the effects of a human urine preparation, CDA-2, on the induction of growth arrest and apoptosis. Apoptotic proteins, including caspase family, Bcl-2 family, the inhibitor of apoptosis protein (IAP) family, and the FLICE-like inhibitory protein (FLIP), as well as cell cycle-associated proteins were studied. The phosphoinositide 3 kinase (PI3K)/Akt survival signaling pathway and the NF-kappaB pathway were also examined. The caspase-3 inhibitor Z-DEVD-fmk was used to examine the involvement of caspase-3 and poly (ADP-ribose) polymerase (PARP). PI3K inhibitor LY294002 was used to examine the involvement of the PI3K/Akt signaling pathway in this apoptosis-inducing effect. MUTZ-1 cell xenografted serious combined immunodeficiency disease mice were used for the in vivo study.

RESULTS

We found that CDA-2 could induce growth arrest and apoptosis of MUTZ-1 cells in vitro and in vivo. The main mechanisms were related to the inhibition of PI3Kp110alpha expression at the transcriptional level, which inactivated the phosphorylation of Akt involving the prevention NF-kappaB phosphorylation and nuclear translocation, the downregulation of the IAP family and FLIPL protein, and the dephosphorylation of the Bad protein, which then triggered the activation of the caspase cascades. This phenomenon could be inhibited by the PI3K inhibitor LY294002 and caspase-3 inhibitor Z-DEVD-fmk.

CONCLUSION

Our results demonstrate the presence of active components in the human urine extract that can induce the growth arrest and apoptosis of MDS-RAEB-derived MUTZ-1 cells and may involve the PI3K/Akt signaling pathway in a caspase-3-dependent manner. This may provide new insights for the treatment of high-risk MDS.