Figure 6

ALT abrogates STAT3 activation through oxidative stress. (A) A549 cells were incubated with ALT for 12 h. Cell lysates were collected and subjected to Western blot for the expression of p-JAK2, JAK2, SHP-2, p-SRC and SRC. (B) Protein expression was normalized to GAPDH. Each bar in graph represents Mean ± SEM of three repeated experiments. Columns not sharing same superscript letters within the group differ significantly (P < 0.05). (C) A549 cells were incubated with or without BaP (2 μM) and Doxorubicin (2 μM) for 7 days. The cells were then treated with ALT in the presence or absence of NAC for another 12 h. Cell extracts were collected and expression of p-STAT3/STAT3 was evaluated by Western blot. (D) Each bar in graph represents Mean ± SEM of three repeated experiments. Columns not sharing same superscript letters within the group differ significantly (P < 0.05). (E) A549 cells were treated with diamide and ALT in the presence or absence of NAC for 4 h. The total cell lysates were collected and subjected to immunoprecipitation (IP) for STAT3 and immunoblotting (IB) for protein linked GSH (PSSG) and STAT3. ALT increased the level of glutathionylated STAT3 as diamide while NAC inhibited ALT-induced STAT3 glutathionylation.