Figure 5.

ROS production and ERK activation are associated with downregulation of STAT3 phosphorylation in Huh-BAT cells co-treated with sorafenib and UDCA. (A) Huh-BAT cells were co-treated with 5 μM sorafenib and 750 μM UDCA for 48 h, followed by 5 mM NAC. Following treatments, ROS intensity was measured using a fluorescence microplate reader. The relative ROS levels were normalized to the mean intensity of ROS in the control untreated cells (presented here as 1.0). (B) Huh-BAT cells were pretreated with 5 mM NAC, or (C) pretreated with 5 μM U0126, prior to 5 μM sorafenib and 750 μM UDCA treatments. Samples were immunoblotted with primary antibodies to STAT3, phospho-STAT3, ERK, and phospho-ERK. β-actin was used as a loading control. ^*P<0.05 and ^**P<0.01 compared with control untreated cells. ROS, reactive oxygen species; ERK, extracellular signal-regulated kinase; STAT3, signal transducer and activator of transcription 3; UDCA, ursodeoxycholic acid; NAC, N-acetyl cysteine.