Objective  To study the effect of Notch signaling pathway on the differentiation of human acute promyelocytic leukemia cell line NB4 induced by Herba Saginae Japonicae ethanol extract (HSJ).

  Methods  The NB4 cells were treated with low-, moderate-, high-dose (30, 60, 120 μg/mL) HSJ for 48 hours and a negative control group was also established. The inhibitive rate of NB4 cell′s proliferation was detected with 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay. The morphology of the NB4 cells was observed with Wright-Giemsa staining. The mRNA and protein expressions of Jagged1, Notch1, and c-myc were detected with real time-PCR and Western blot, respectively.

  Results  Compared with that of the control group, the proliferation of HSJ-treated NB4 cells was inhibited significantly, with the observed cells′ mature morphology as decreased nucleus/cytoplasm ratio and reniform and lobulated nuclei. In comparison to those of the control group, significantly decreased mRNA expressions of Jagged1 (0.78 ± 0.10, 0.32 ± 0.15, and 0.07 ± 0.02) and c-myc (0.88 ± 0.05, 0.67 ± 0.02, and 0.47 ± 0.16) and significantly increased mRNA expression of Notch1 (1.27 ± 0.14, 1.39 ± 0.23, and 1.53 ± 0.30) were observed for the NB4 cells treated with low-, moderate-, and high-dose HSJ (P < 0.05 for all); significantly decreased protein expressions of Jagged1 (0.95 ± 0.10, 0.69 ± 0.02, and 0.59 ± 0.01) and c-myc (0.82 ± 0.14, 0.70 ± 0.07, and 0.65 ± 0.20) and significantly increased protein expression of Notch1 (0.56 ± 0.08, 0.81 ± 0.03, and 1.33 ± 0.14) were also observed for the NB4 cells treated with low-, moderate-, and high-dose HSJ (all P < 0.05).

  Conclusion  HSJ can induce mature differentiation of NB4 cells and the mechanism of the effect may be related to Notch signaling pathway.