[Experimental study on human leukemia cell line K562 senescence induced by ginsenoside Rg1]

OBJECTIVE To observe the effect and mechanism of ginsenoside Rg1 in inducing senescence human leukemia K562 cell line. METHOD Proliferation of K562 cell line induced by Rg1 was detected by MTT colorimetric test for the purpose to screen optimal active concentration and time (20 micromol x L(-1) , 48 h). Impact of Rg1 on cell cycle was analyzed using flow cytometry. The percentage of staining positive cells was detected by SA-beta-Gal staining. The expressions of senescence-related genes such as p16, p53, p21, Rb, were detected by RT-PCR and the changes in ultramicro-morphology were observed by transmission electron microscopy. RESULT Rg1 can significantly inhibit the proliferation of K562 cells in vitro and arrest the cells in G2/M phase. The percentage of positive cells stained by SA-beta-Gal was dramatically increased (P < 0.05) and the expression of cell senescence-related genes were up-regulated. The observation of ultrastructure showed that cell volume increase, heterochromatin condensation and fragmentation, mitochondrial volume increase, lysosomes increase in size and number. CONCLUSION Rg1 can induce the senescence of leukemia cell line K562 and play an important role in regulating p53-p21-Rb, p16-Rb cell signaling pathway.