Antitumor effect of interferon-alpha on U937 human acute leukemia cells in vitro and its molecular mechanism.

In order to investigate the antitumor effect and molecular mechanism of interferon-alpha (IFN-alpha) on human acute myeloid leukemia cell line U937 cells in vitro, the proliferation of U937 cells was determined by MTT assay, the apoptosis rate was analyzed by flow cytometry (FCM), and the mRNA expression of cell cycle regulatory protein cyclin E was detected by RT-PCR. The results showed that IFN-alpha could inhibit the proliferation of U937 cells significantly in a dose-and time-dependent way (P<0.01), and induce the apoptosis of U937 cells also in a dose-and time-dependent manner at the concentration of 1000-4000 U/L (P<0.01). The apoptosis rate of U937 cells was even over 50% when cultured with IFN-alpha for 36-48 h at the concentration of 2000-4000 U/L. Moreover, the expression of cyclin E mRNA was markedly inhibited by the addition of IFN-alpha, and the inhibition was time-dependent (P<0.01). It was concluded that the anti-leukemia mechanism of IFN-alpha might be correlated with its antiproliferative and apoptotic inducing effects, and the down-regulation of the cyclin E expression might be one of its molecular mechanisms.