Inhibitory effect of JQ1 on proliferation of acute myeloid leukemia U937 cell line and its effect on the signal transduction pathway of STAT-5

Abstract

Objective To study the suppressive mechanism of the bromo structural domain inhibitor JQ1 on the acute myeloid leukemia cell line U937 and its regulation of the STAT-5 signaling pathway. Methods U937 cells in the logarithmic growth phase were tested. Each experimental group was fed with 0.2, 1.0 and 4.0 μmol/L of JQ1, and a blank control group without JQ1 was set up. U937 cells were cultured for 48 h, and the cell proliferation inhibitory rate was measured by MTT assay. Flow cytometry (FCM) was used to detect the apoptotic rate. Real-time fluorescence quantitative polymerase chain reaction (RT-PCR) was used to detect the mRNA expression of focal adhesion kinase (FAK) and P21 activated kinase (PAK1). The expression of STAT-5 protein was analyzed by Western blot. Results Different concentration of JQ1 could inhibit the proliferation of U937 cells in a time and dose-dependent manner, and different concentration of JQ1 could induce the apoptosis of U937 cells in a dose-dependent manner. Treatment of U937 cells with different concentrations of JQ1 (0.2, 1.0 and 4.0 μmol/L) reduced the expression of FKA mRNA and PAK1 mRNA after 48 h, the expression of FAK mRNA was 0.417±0.066, 0.140±0.026, and 0.027±0.006 (F = 454.651, P = 0.000), and the expression of PAK1 mRNA was 0.533±0.045, 0.080±0.010, and 0.010±0.001 (F = 2 434.610, P = 0.000), and STAT-5 protein expression was also significantly inhibited. The expression of STAT-5 protein in U937 cells after treated with different concentrations of JQ1 (0.2, 1.0 and 4.0 μmol/L) for 48 h were 0.71±0.19, 0.62±0.16, 0.53±0.14, and 1.00±0.21 in the control group (F = 263.135, P = 0.000). Conclusion JQ1 can effectively inhibit the proliferation of the acute myeloid leukemia cell line U937 cells and induce their apoptosis, and the possible mechanism of action is regulated via STAT-5 signaling pathway. Key words: Leukemia, myeloid, acute; Cell line, U937; JQ1; STAT-5