Fig. 4

CREB5 regulates mitochondrial activity through TOP1MT. A–D Real-time OCR measurement of HN4 and HN30 cells treated as indicated. Cells were incubated with 1 μM oligomycin (O), 0.5 μM luoro-carbonyl cyanide phenylhydrazone (F), and 1 μM antimycin (A) for the indicated times. E, F Mito-Tracker Red CMXRos was used to detect the effect of CREB5 and TOP1MT expression on mitochondrial activity in parent and cisplatin-resistant cells. G, H Relative red fluorescence (Mito-Tracker Red CMXRos) values are shown. I, J The effect of CREB5 and TOP1MT expression on ATP levels was analyzed in HN4, HN30, HN4/DDP, and HN30/DDP cells. K Immunoblotting was used to detect the expression levels of CREB5, TOP1MT, Bcl-2, Bcl-xL, Bax, cytochrome c, caspase 3, cleaved caspase 3, caspase 7, cleaved caspase 7, PARP, cleaved PARP, and GAPDH in HN4 and HN30 CREB5 cells with TOP1MT knockdown. L Immunoblotting was used to detect the expression levels of CREB5, TOP1MT, Bcl-2, Bcl-xL, Bax, cytochrome c, caspase 3, cleaved caspase 3, caspase 7, cleaved caspase 7, PARP, cleaved PARP, and GAPDH in HN4/DDP and HN30/DDP siCREB5 cells with TOP1MT overexpression. *p < 0.05; **p < 0.01; ***p < 0.001; ****p < 0.0001