Effects of 15d-PGJ2 on the anti-cancerous activities of topoisomerase inhibitors in RCC4 (+) cells. RCC4 (+) cells were treated with CPT (A), VP-16 (B), DOX (C) or 15d-PGJ2 (D) at the indicated concentrations for 24 h. Cell viabilities were determined by MTT-reducing activity. Data are expressed as means ± SE. (n = 3). *P < 0.05, compared with control, **P < 0.01, compared with control. (E) RCC4 (+) cells were treated with 0.05 μM CPT, 20 μM VP-16 or 1 μM DOX in the absence (open column) or presence (closed column) of 20 μM 15d-PGJ2 for 24 h. Cell viabilities were determined by MTT-reducing activity. Data are expressed as means ± SE. (n = 6). **P < 0.01, compared with control. ##P < 0.01, compared with each topoisomerase inhibitor alone. (F) RCC4 (+) cells were treated with 0.05 μM CPT, 20 μM VP-16 or 1 μM DOX in the 0.05 absence or presence of 20 μM 15d-PGJ2 for 24 h. Morphologies were photographed by phase contrast. Scale bar = 100 µm.