Fig. 1

Autophagy inhibition contributes to synergistic interaction between EGCG and Doxorubicin to kill the osteosarcoma cells. a Combination of EGCG and DOX synergistically facilitate antitumor effects in U2OS and SaoS2 cell lines. Columns, percentage of inhibition ratio; bars, SE. Data was from a representative of 5 independent studies. ^a p < 0.05 vs. control group treated without EGCG but only 1 μm Dox, ^b p < 0.05 vs. control group treated without EGCG but only 2.5 μm Dox. b Immunofluorescence analysis indicated that elevated LC3 fluorescent punctual signals were visualized in cells administrated with 2.5 mM DOX, while when EGCG was added, the LC3 fluorescence signal becomes weaker. c Exposed to 2.5 μM Dox with or without 20 μg/ml EGCG for 24 h, the expression levels of Atg5, Atg7 and Beclin1 in OS cells were determined at the mRNA levels by qRT-PCR. Results shown are representative of three independent experiments and error bars indicate SE. ^* p < 0.05 vs. DOX single treated group. d Cell lysates following DOX treatment with or without EGCG were subjected to western blotting. Protein ratios normalized to β-actin were used to quantify fold change. e Cells were under different treatment, then MTT assay was performed to detect the growth inhibition. Data was from a representative of 5 independent studies. ^a p < 0.05 vs. DOX treated group without 3-MA, ^b p < 0.05 vs. combined treated group without Rapa