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[Apoptosis of human chronic myeloid leukemia k562 cell induced by prosapogenin B of dioscin (P.B) in vitro].

BACKGROUND & OBJECTIVE
The authors have isolated prosapogenin B of dioscin (P.B) newly from Dioscorea futschauensis R. Kunth (Dioscoreaceae) and found that P.B could significantly inhibit the cell proliferation of several human cancer cell lines for the first time. The objective of this paper was designed to investigate whether P.B could inhibit cancer cell proliferation by inducing apoptosis.


METHODS
Morphological changes of cell nuclei were observed under invert fluorescence microscope and transmission electron microscope. The changes in the cell size distribution were analyzed by Coulter Multisizer II particle analyzer. DNA ladder and apoptotic cells were analyzed respectively by DNA agarose gel electrophoresis and flow cytometry.


RESULTS
The K562 cells treated with 10 micromol/L P.B for 24 hours showed morphological characteristics of apoptotic cells, such as decrease in cellular volume, nuclear chromatin condensation, nuclear fragmentation, and plasma membrane bleb formation. The treatment of K562 cells with 10 micromol/L P.B for 6, 12,and 24 hours caused the increase of the detected DNA ladder and the decrease of normal size cells both in a time-dependent manner. The percentage of apoptotic bodies detected in the sub-G(0)/G(1) peak region by flow cytometry was also increased time-dependently as analyzed as 6.12% for 6 hours, 35.6% for 12 hours and 45.7% for 24 hours treatments, respectively.


CONCLUSION
These results suggested that P.B exerts its anti-proliferative effect on K562 cells through inducing apoptosis of the cells.