Objective: The present study investigates the effects of Tanreqing injection, a compound Chinese herbal medicine, on the proliferation of leukemia cells in vitro and discusses the potential mechanisms.
Methods: Tanreqing injection was diluted to a series of concentrations (1:2, 1:4, 1:8, 1:16, 1:32, 1:64, 1:128, 1:256 and 1:512) by volume and then independently applied to treat chronic myeloid leukemia K562 cells and T cell acute lymphocytic leukemia Molt4 cells at the proliferative stage. Cell growth was observed at different time intervals under a microscope. Cell proliferation was determined by cell counting kit-8 assay and the survival curve was delineated. The inhibitory rate and the half inhibitory concentration (IC50) were calculated. Molt4 cells were stained with propidium iodide (PI) and PI/Annexin V and then the cell cycle and apoptosis were analyzed by using flow cytometry. In addition, a real-time quantitative polymerase chain reaction was subjected to detect the expressions of apoptosis-related genes (bcl-2 and caspase-3) after Tanreqing treatment.
Results: Tanreqing injection had inhibitory effects on the proliferation of K562 cells and Molt4 cells. The most toxic concentrations were observed between 1:2 and 1:16 where cells were almost necrotic. The inhibitory effect manifested in a concentration- and time-dependent manner. The IC50 of K562 and Molt4 was 1:333 and 1:142, respectively. After 1:32 Tanreqing injection treatment for 72 h, the number of Molt4 cells in the S phase significantly decreased (P<0.05), and the apoptosis rate markedly increased (P<0.05). In addition, increased caspase-3 expression and decreased bcl-2 expression were also observed (P<0.05).
Conclusion: Tanreqing injection can both inhibit the proliferation and promote the apoptosis of leukemia cells in vitro, whereby the potential mechanism seems to be mediated in part by decreasing S phase ratio, down-regulating bcl-2 expression and up-regulating caspase-3 expression.