Effects of Rehmannia glutinosa polysaccharides on the proliferation and apoptosis of K562 cells

Leukemia is one of the malignant tumors of hemopoietic system which is characterized by the block of hematopoietic cell differentiation and maturation, increased proliferation of undifferentiated cells and impairment of normal apoptosis process. The proliferating leukemia cells accumulated in bone marrow and other hemopoietic tissue, infiltrated other organs and tissues, so that the normal hematopoiesis will be inhibited. Chemotherapy is currently the most effective means of treatment of leukemia which has greatly improved survival rate, but it also induces undesirable adverse effects and high recurrence rate. Therefore, it is necessary to search for new drugs with low toxicity for the treatment of leukemia. Rehmannia glutinosa is a traditional Chinese medcine and polysaccharides of Rehmannia glutinosa (RPS) were reported to have the immune stimulatory effect and anti-tumor effect both in vivo and in vitro. After incubating K562 cells (a kind of chronic mylogenous leukemia cell model) with different concentration of RPS, we found that RPS could induce cells arrest in G0/G1 phase and apoptosis, meanwhile, the cell proliferation was also inhibited. Moreover, the expression of Bcl2 was downregulated, and the activity of Caspase3 was improved after incubating K562 cells with RPS for 48 h.