Relative expression of miR-155 in GBC cell lines and the effect of transfection on the miR-155 expression level. (A) The expression levels of miR-155 in the GBC lines were investigated by qRT-PCR. miR-155 expression levels were normalized to RNU6B expression. Human GBC cell lines, G-415 (isolated from a GBC of a 68-year-old Japanese male), OCUG-1 (isolated from the GBC of a 43-year-old Japanese male), and NOZ (isolated from the ascites of a 48-year-old Japanese female with GBC), were used in the present study. miR-155 expression levels in G-415, NOZ and OCUG-1 cells were 56.8-, 18.1- and 4.2-fold, respectively. (B-D) Effects of transfection of miR-155 inhibitors or mimics on each GBC cell line were assessed by qRT-PCR. Each expression level of miR-155 was normalized to RNU6B expression. Expression levels of miR-155 in G-415, NOZ and OCUG-1 cells transfected with miR-155 inhibitors were downregulated by 0.12-, 0.35- and 0.17-fold, respectively, when compared with levels in the negative controls. The expression levels of miR-155 in G-415, NOZ and OCUG-1 cells transfected with miR-155 mimics were upregulated by 23.6-, 124- and 27,605-fold, respectively, when compared with levels in the negative controls. miR; microRNA.