Objective: To study the anti-proliferative and apoptotic effects of the combined application of casticin (CAS) and (-)-Epigallocatechin gallate(EGCG) on A549 lung cancer cells. Method: A549 lung adenocarcinoma cells were incubated

and those with the activity of at least 95% during logarithmic phase were assayed. Next

the anti-proliferative effect of the combined application of CAS (0.5

1

5

10

15

20 μmoL·L-1) and EGCG (1

5

10

15

20

25 μmoL·L-1) on A549 cells was detected by sulforhodamine B (SRB) method. After that

the intracellular distribution of CAS and EGCG was observed under confocal laser scanning microscope. Flow cytometry was used to detect the apoptosis of A549 lung cancer cells. Protein expressions of B-cell lymphoma-2 (Bcl-2) and Bcl-2 associated X protein (Bax) in A549 cells were detected by Western blot. Result: The inhibitory rates of these two drugs with different concentrations against A549 cells were statistically different (P<0.05) at 24

48 h. Additionally

the inhibitory rates of the combined application of CAS+EGCG were significantly higher than the single application of CAS or EGCG with the same concentration(P<0.05). When the cells were incubated for 24 hours after the treatment with 5 μmoL·L-1CAS and 10 μmoL·L-1 EGCG

the drugs showed an anti-proliferative effect on A549 cells with synergy. Moreover

at 48 hour after the treatment

the combined application of 0.5 μmoL·L-1 CAS and 1 μmoL·L-1 EGCG

1 μmoL·L-1 CAS and 5 μmoL·L-1 EGCG

15 μmoL·L-1 CAS and 20 μmoL·L-1EGCG

as well as 20 μmoL·L-1CAS and 25 μmoL·L-1 EGCG showed an increased effect on the inhibitory rates on A549 adenocarcinoma cells. According to the observation under laser confocal microscope

the number of the group of CAS (5 μmoL·L-1) and EGCG (10 μmoL·L-1) entering A549 cells was obviously higher than the single application of CAS or EGCG with the same concentration. Meanwhile

after the cells were treated for 24 h

the apoptotic rate of the combined application of CAS and EGCG were obviously higher than that of the single application of CAS or EGCG with the same concentration (P<0.05). The expressions of Bax protein of EGCG were obviously higher than that of the single application of CAS or EGCG with the same concentration

while the expression of Bcl-2 was lower than that of the single application of CAS or EGCG with the same concentration (P<0.05). Conclusion: The inhibitory and apoptotic effects of co-administrated with CAS and EGCG on A549 lung cancer cells were significantly enhanced compared with those of the single administration

which may be related to Bcl-2 and Bax proteins.