Figure 2

Cisplatin-resistant cells exhibit cross-resistance to DNA-damaging agents but not death-receptor signaling. A549 WT and the cisplatin-resistant cells were treated with (a) 5-fluorouracil (μM), (b) etoposide (μM), (c) gemcitabine (mM), (d) TRAIL (ng/ml) or (e) Fas activating antibody (μg/ml) at the indicated doses for 24 h. Cell viability was determined by MTT assay and expressed as % of untreated control. *^,#P<0.05 and **^,##P<0.005 compared with WT treated at respective dose. (f) Western blot analysis of various proteins important in regulating mitochondria-mediated apoptotic signaling. β-Actin was used as a loading control. (g) Oxygen consumption of WT and R1 cells were assessed using a Clark electrode. State 3 respiration was initiated with addition of exogenous 0.2 mM ADP (arrow). The slope of the curve is a measure of the rate of oxygen consumption for a period of 20 min. Respiratory ETC complex I (h), II (i) and IV (j) activities were measured in WT and R1 cells using the 96-well enzymatic-based microplate assay kit. *P<0.05 and **P<0.005 compared with WT control. ΔmOD indicates change in maximum OD at 340nm. Data shown are mean±S.D. of at least three independent experiments