OBJECTIVE:To investigate the effect of optimal combination (E) of Huangqi (Radix Astragali Mongolici) and Ezhu (Rhizoma Curcumae Phaeocaulis) on proliferation and apoptosis of A549 lung cancer cells and the possible mechanism underpinning the action.METHODS:A uniform design method was used to optimize the E of Huangqi (Radix Astragali Mongolici) and Ezhu (Rhizoma Curcumae Phaeocaulis) in A549 lung cancer cells.MTS assay was applied to analyze the effect of the component formula of Huangqi (Radix Astragali Mongolici) and Ezhu (Rhizoma Curcumae Phaeocaulis) on A549 cells viability in various uniform design groups.A549 cells with exponential growth in routine culture were exposed to CoCl2 (200 μmol/L) to mimic hypoxic conditions.Group 0 was treated with RPMI-1640,the group CoCl2 was treated with CoCl2 (200 μmol/L),the group DDP + CoCl2 was treated with 4 mg/L Cisplatin injection (DDP) + CoCl2 (200 μmol/L),and the drug group was treated with various dose of E (0.5E,1 E,2E) + CoCl2 (200 μmol/L).All groups were cultured for 24 h.Cell apoptosis was measured by Annexin V-FITC/propidium iodide double staining and flow cytometry.West blot assay and quantitative real-time polymerase chain reaction (qRT-PCR) were employed to detect the protein and mRNA expression of B-celllymphoma-2 (Bcl-2),Bcl-2-associated X protein (Bax) and cysteinyl aspartate specific proteinase-3 (caspase-3).RESULTS:The E obtained by the uniform design was comprise of 200 mg/L Astragalus polysaccharide (X1) and 32 mg/L Curcumin (X3).Group DDP+CoCl2,group 1E + CoCl2 and group 2E + CoCl2 promoted the apoptosis of A549 cells (P ＜ 0.05).Group 1E + CoCl2 and group 2E + CoCl2 had no statistically significant differences compared with the group DDP + CoCl2 (P ＞ 0.05).Compared with group 0,various doses of E + CoCl2 could up-regulate the expression of Bax and caspase-3 and down-regulate the expression of Bcl-2 at protein and mRNA levels (P ＜ 0.05).CONCLUSION:Astragalus polysaccharide and Curcumin was the optimal combination of Huangqi (Radix Astragali Mongolici) and Ezhu (Rhizoma Curcumae Phaeocaulis).E promoted the apoptosis of A549 cells.Combination of Astragalus polysaccharide and Curcumin increased the expression of Bax and caspase-3,and decreased the expression of Bcl-2 to initiate apoptosis in A549 cells under chemical-induced hypoxia.