Effects of Coix Seed Extract on Apoptosis and Ultrastructure of Human Pancreatic Cancer Cells

Background: Coix seed extract is now widely used in the treatment of cancers clinically, however, its effect on pancreatic cancer has not been investigated yet. Aims: To observe the effects of coix seed extract on apoptosis and ultrastructure of human pancreatic cancer cells, so as to seek a new approach in treating pancreatic cancer. Methods: Human pancreatic cancer cell line PaTu-8988 was exposed to different concentrations of coix seed extract. The apoptosis was evaluated by light microscopy, Hoechst 33258 fluorescence staining, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) and flow cytometry, respectively. The ultrastructural changes of PaTu-8988 cells were observed by transmission electron microscope. Results: The proliferative activity of PaTu-8988 cells pretreated with coix seed extract (10 μl/ml and 20 μl/ml) for 72 hours decreased in a dose-dependent manner. Light microscopy showed that the apoptotic cells became rounder and smaller, and were positively stained with fluorochrome Hoechst 33258 and TUNEL method. Flow cytometric analysis showed the appearance of a population of cells containing hypodiploid DNA in a time-dependent manner, the apoptosis rates induced by coix seed extract (20 μl/ml) were 7.1%±0.6% at 24 h, 11.3%±0.3% at 48 h and 15.1%±2.9% at 72 h, all higher than that of the control group (2.4%±1.1%, P0.01). The early apoptotic change under transmission electron microscope was mainly the structural changes of mitochondria, then the classical ultrastructural feature of apoptosis, such as karyopyknosis, chromatic agglutination adjacent to the nuclear membrane and apoptotic body were found in late stage. Conclusions: The coix seed extract can induce apoptosis of human pancreatic cancer cells in a dose- and time-dependent manner, and the mitochondria might play a significant role in the early stage of apoptosis.