Promotive effect of C/EBPepsilon overexpression on differentiation of human myelomonocytic leukemia cell line U-937.

BACKGROUND & OBJECTIVE: CCAAT-enhancer binding protein omega (C/EBPepsilon) is a kind of nuclear transcriptional factor expressed predominantly in myeloid cells, and may be a critical regulator of myeloid differentiation, which can activate the transcription of a subset of myeloid-specific genes. This study was to detect the cell-specific expression of C/EBPepsilon, and to investigate the effect of C/EBPepsilon overexpression on c-Myc expression, cell cycle distribution, and cell differentiation of human myelomonocytic leukemia cell line U-937.

METHODS: The expression of C/EBPepsilon in 5 hematopoietic cell lines (U-937, NB4, HL-60, K-562 and Jurkat T cell lines) was tested by semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR). According to the RT-PCR results, human myelomonocytic leukemia cell line U-937 was selected and transfected with pcDNA3.1-C/EBPepsilon32 expression vector by electroperforation, and screened by G418 to yield positive clones which were termed U-937-C/EBPepsilon32. The expression of C/EBPepsilon and c-Myc in U937-C/EBPepsilon32 cells was detected by RT-PCR and Western blot; cell cycle and differentiation of U937-C/EBPepsilon32 cells was analyzed by flow cytometry.

RESULTS: C/EBPepsilon overexpression obviously increased the expression of CD11b (a cell surface marker of granulocyte maturity). The positive rate of CD11b was significantly higher in U-937-C/EBPepsilon32 cells than in U-937 and U-937-pcDNA3.1 cells(92.56% vs. 77.46% and 74.81%), while c-Myc expression and cell cycle had no changes.

CONCLUSION: C/EBPepsilon might be an essential transcriptional regulator for U-937 cells differentiating into granulocytes.