Objective: To investigate the effects of toosendanin on the glycolysis of breast cancer cells and the effect on glycolytic enzymes. Method: The human breast cancer cell line MDA-MB-231

MCF-7 were used in this experiment; the inhibitory effect of different concentrations of toosendanin (0

2.5

5

10

20

40

60

80 μmol · L-1) on MDA-MB-231and MCF-7 cells proliferation was investigated by methylthiazolyldiphenyl-tetrazolium bromide (MTT) assay. Glucose consumption and lactate content in MDA-MB-231 and MCF-7 cells were also detected after treatment with 10

20

40 μmol · L-1 toosendanin to evaluate its intervention effect on glycolysis of breast cancer cells. The levels of adenosine triphosphate (ATP) and nicotinamide adenine dinucleotide (NAD+)/reduced nicotinamide adenine dinucleotide phosphate (NADH) in breast cancer cells were detected to evaluate the cell energy supply level. Hexokinase and pyruvate kinase activities were detected to evaluate the effect of toosendanin on glycolytic enzyme activity. Western blot was used to detect the regulatory effect of toosendanin on pyruvate kinase M2 protein expression in breast cancer cells. Result: The results showed that toosendanin had obvious inhibitory effect on cell proliferation in MDA-MB-231and MCF-7 cells in a concentration dependent manner(P<0.05). Toosendanin could significantly reduce the consumption of glucose and lactic acid content in different breast cancer cell lines(P<0.05)

and reduce ATP content in cells(P<0.05)

increase the content of NAD+/NADH

and inhibit tumor cell glycolysis level (P<0.05). In addition

it could inhibit the activity of pyruvate kinase

but had no effect on the activity of hexokinase 2

and the results of quantitative analysis showed that the expression of pyruvate kinase M2 could be decreased(P<0.05). Conclusion: Toosendanin could significantly inhibit the proliferation of breast cancer cells and affect the level of glycolysis. Its mechanism may be associated with regulating the expression of pyruvate kinase M2 in breast cancer cells.