Figure 4.

ATF3 induction by cisplatin is mediated by MAPK pathways in MCF-7 cells. (A) MCF-7 cells without treatment (control) and those treated with anisomycin (20 µM) for 1 hour and cisplatin (10 µg/ml) or carboplatin (270 µg/ml) for the 4-, 8-, 12-, and 24-hour time points were analyzed by Western blot analysis for the detection of ATF3, actin, phospho-c-jun (p-c-jun), and total c-jun (left panel). MCF-7 cells similarly treated with cisplatin or carboplatin in the absence (0) or presence of JNK pathway inhibitor (SP; 25 and 50 µM) for 24 hours were analyzed for the detection of ATF3, actin, p-c-jun, and total c-jun (right panel). (B) MCF-7 cells without treatment (control) and those treated with anisomycin (20 µM) for 1 hour and cisplatin or carboplatin as previously mentioned for the 4-, 8-, 12-, and 24-hour time points were analyzed by Western blot analysis for the detection of ATF3, actin, phospho-ERK (p-ERK), and total ERK (left panel). MCF-7 cells treated with cisplatin or carboplatin in the absence (0) or presence of ERK pathway inhibitor (UO126; 10 and 25 µM) for 24 hours were analyzed for the detection of ATF3 and actin and at 4 hours for p-ERK and total ERK (right panel). (C) MCF-7 cells untreated (control), treated with tumor necrosis factor α (20 ng/ml) for 15 and 30 minutes, and cisplatin or carboplatin for the 9- and 24-hour time points were analyzed by Western blot analysis for the detection of ATF3, actin, phospho-p38 (p-p38), and total p38 (left panel). MCF-7 cells treated with cisplatin or carboplatin in the absence (0) or presence of p38 inhibitor, SB203580 (SB; 5 and 10 µM), for 24 hours were analyzed for the detection of ATF3, actin, phospho-hsp27 (p-hsp27), and total hsp27 (right panel). (D) PC3 cells treated with cisplatin (10 µg/ml) or carboplatin (270 µg/ml) in the absence (0) or presence of p38 inhibitor, SB203580 (SB; 5 and 10 µM), for 24 hours were analyzed for the detection of ATF3, actin, phospho-hsp27 (p-hsp27), and total hsp27.