Fig. 6

Low glucose and metformin activate ER stress through the ROS/ASK1/JNK pathway. a After SKOV3 and OVCRA3 cells were pretreated with 40 μM NAC, flow cytometry was used to analyze the relative ROS level using DCFH-DA in cells treated with 25 mM or 2.5 mM glucose and metformin for 24 h. Data are presented as a mean ± SD (n = 3; **P < 0.01 versus 2.5 mM glucose alone; ^##P < 0.01 versus combination of 2.5 mM glucose and metformin). b-d After SKOV3 cells were pretreated with 10 μM NQDI-1, (b) the expression of PDI was observed in cells treated with 2.5 mM glucose and metformin for 24 h (bar, 10 μm). c Western blot analysis of the expression of GADD153, caspase 4, and cleaved caspase 4 in cells treated with 2.5 mM glucose and metformin for 24 h. d Quantitation of the ratio of GADD153 and cleaved Caspase 4 proteins. Data are presented as mean ± SD (n = 3; *P < 0.05 and **P < 0.01 versus 2.5 mM glucose alone; ^##P < 0.01 versus combination of 2.5 mM glucose and metformin)