Fig. 3

ID1 activates pentose phosphate pathway and confers chemoresistance to oxaliplatin in HCC through G6PD. a PCR array analysis of the differentially expressed genes in 97H Ctrol and 97H–shID1 cells. b and c Among these differentially expressed genes, G6PD was downregulated upon ID1 knockdown, as illustrated by Western blot and Real-time RT-PCR assays(* P < 0.05). d The enzyme activity of G6PD was measured in oxaliplaitin resistant cell lines. ID1 knockdown inhibited the enzyme activity of G6PD in 97H–OXA-shID1 and 3B–OXA-shID1cell lines (P = 0.03 and P = 0.02). After transfecting G6PD plasmid into ID1-knockdown 97H–OXA-shID1 or 3B–OXA-shID1 cells, enzyme activity of G6PD were recovered (e) NADP+ /NADPH ratios were determined through enzymatic assays. ID1 knockdown inhibited NADPH accumulation. Recovery of G6PD expression in 97H–OXA-shID1 and 3B–OXA-shID1cell lines increased NADPH accumulation. Data are presented as mean ± SD of n = 3 independent experiments. f Quantification of ROS level was measured using flow cytometry assay. ID1 silencing increased ROS generation in 97H–OXA-shID1 and 3B–OXA-shID1 cell lines (P = 0.005 and P = 0.001, respectively). Recovery of G6PD expression in 97H–OXA-shID1 and 3B–OXA-shID1cell lines inhibited ROS generation. Data are presented as mean ± SD of n = 3 independent experiments