Nardostachys chinensis induces granulocytic differentiation with the suppression of cell growth through p27(Kip1) protein-related G0/G1 phase arrest in human promyelocytic leukemic cells.

Context: Nardostachys chinensis Batalin (Valerianaceae) has been used in Korean traditional medicine to elicit stomachic and sedative effects. However, the anti-leukemic activities of N. chinensis have not been well examined. Objective: To investigate the effect of N. chinensis on differentiation and proliferation in the human promyelocytic leukemic HL-60 cells. Materials and methods: The dried roots and stems of N. chiensis are extracted using hot water and then freeze-dried. The yield of extract was 12.82% (w/w). The HL-60 cells were treated with 25-200 mu g/ml of N. chinensis for 72 h or 100 mu g/ml of N. chinensis for 24-72 h. Results: Nardostachys chinensis significantly inhibited cell viability dose dependently with an IC50 of 100 mu g/ml in HL-60 cells. Nardostachys chinensis induced differentiation of the cells as measured by reduction activity of NBT and expression of CD11b but not of CD14 as analyzed by flow cytometry, which indicates a differentiation toward the granulocytic lineage. Nardostachys chinensis also induced growth inhibition through G(0)/G(1) phase arrest in the cell cycle of HL-60 cells. Among the G(0)/G(1) phase in the cell cycle-related protein, the expression of cyclindependent kinase (CDK) inhibitor p27(Kip1) was increased in N. chinensis-treated HL-60 cells, whereas the expression levels of CDK2, CDK4, CDK6, cyclin D1, cyclin D3, cyclin E, and cyclin A were decreased. Interestingly, N. chinensis markedly enhanced the binding of p27(Kip1) with CDK2 and CDK6. Discussion and conclusion: This study demonstrated that N. chinensis is capable of inducing cellular differentiation and growth inhibition through p27(Kip1) protein-related G(0)/G(1) phase arrest in HL-60 cells.