Figure 7
Quercetin synergizes with EGCG to inhibit self-renewal capacity of prostate cancer CSCs isolated from primary tumors. (A), Quercetin synergizes with EGCG to inhibit spheroid cell viability. Prostate CSCs were seeded in suspension and treated with EGCG (0-60 μM) with or without quercetin (20 μM) for 7 days. At the end of incubation period, all the spheroids were collected and resuspended. Cell viability was measured by trypan blue assay. Data represent mean ± SD. *, &, **, @ or # = significantly different from control, P < 0.05. (B), Quercetin synergizes with EGCG to inhibit colony formation. Prostate CSCs were seeded in soft agar and treated with various doses of EGCG (0-60 μM) with or without quercetin (20 μM) and incubated at 4°C for 21 days. At the end of incubation period, colonies were counted. Data represent mean ± SD. *, &, **, @ or # = significantly different from control, P < 0.05. (C), Quercetin synergizes with EGCG to induce apoptosis. Prostate CSCs were seeded in suspension and treated with EGCG (0-60 μM) with or without quercetin (20 μM) for 7 days. At the end of incubation period, all the spheroids were collected. Apoptosis was measured by TUNEL assay. Data represent mean ± SD. *, &, **, @ or # = significantly different from control, P < 0.05. (D), Migration assay. Prostate CSCs were plated in the top chamber of the transwell and treated with EGCG (0-60 μM) with or without quercetin (20 μM) for 24 h. Cells migrated to the lower chambered were fixed with methanol, stained with crystal violet and counted. Data represent mean ± SD. *, &, **, @ or # = significantly different from control, P < 0.05. (E) Matrigel invasion assay. Prostate CSCs were plated onto the Matrigel-coated membrane in the top chamber of the transwell and treated with EGCG (0-60 μM) with or without quercetin (20 μM) for 48 h. Cells invaded to the lower chambered were fixed with methanol, stained with crystal violet and counted. Data represent mean ± SD. *, &, **, @ or # = significantly different from control, P < 0.05.