Loss of IRF8 inhibits the growth of acute myeloid leukemia cells.

The transcription factor interferon regulatory factor 8 (IRF8), as a member of the IRF family, is essential for myeloid cell differentiation. However, the precise role of IRF8 in the pathogenesis of acute myeloid leukemia (AML) remains unknown. By using multivariate analysis, we discovered that high IRF8 expression was an independent poor predictor of overall survival (OS) in AML patients from our clinical follow-up study. The proliferation of three AML cell lines was significantly inhibited by shRNA-mediated knockdown of IRF8, owing to cell cycle S-phase arrest. Furthermore, we demonstrated that knocking down IRF8 could suppress the expression of CyclinA and CyclinB1, resulting in a shift in cell cycle distribution. Loss of IRF8 in AML cells decreased the expression of STAT3 and phosphor-STAT3 (pSTAT3), which are key factors in JAK/STAT signal pathway and are important for AML progression. Using a xenograft mouse model, we discovered the antiproliferative effect of losing IRF8 in vivo. In conclusion, this study found that IRF8 may play a prognostic factor and therapeutic target in AML.