Fig. 7

Expressions of IL-6 receptor (IL-6R) mRNA and cell proliferation assay in colorectal cancer cell lines. A IL-6R mRNA expression of relative to glyceraldehyde-3-phosphate dehydrogenase (GAPDH) mRNA expression in colorectal cancer cell lines HCT116 and SW480. The mRNA expression of IL-6R was significantly lower in HCT116 than that in SW480 (Relative expression of IL-6R; HCT116, 0.29 ± 0.13; SW480, 1.00 ± 0.16; P < 0.01). For relative expression, the mean value of SW480 was set to 1. B Effect of recombinant IL-6 on HCT116 and SW480. Treatment of recombinant IL-6 suppressed the proliferation of SW480 cells (absorbance value of CCK-8; IL-6 0 ng/ml, 100 ± 3.7%; IL-6 0.01 ng/ml, 77 ± 2.4%; P < 0.01), although the treatment did not suppress the proliferation of HCT116 cells (absorbance value of CCK-8; IL-6 0 ng/ml, 100 ± 11.2%; IL-6 0.01 ng/ml, 91 ± 10.9%). C IL-6R mRNA expression in mock cells (SW480^mock), and IL-6R knocked down cell (SW480^IL-6R-ND1, and SW480^IL-6R-ND2) mRNA expressions of IL-6R in SW480^IL-6R-ND1 and SW480^IL-6R-ND2 were significantly lower than that in mock cells (SW480^mock) (Relative expression of IL-6R; SW480^mock, 1.00 ± 0.15; SW480^IL-6R-ND1, 0.27 ± 0.11, P < 0.05; SW480^IL-6R-ND2, 0.17 ± 0.06, P < 0.01). For relative expression, the mean value of SW480^mock was set to 1. D Effect of recombinant IL-6 on mock cells (SW480^mock), and IL-6R knocked down cell (SW480^IL-6R-ND1, and SW480^IL-6R-ND2). Treatment of recombinant IL-6 did not suppress proliferation of SW480^IL-6R-ND1 (Absorbance value of CCK-8; IL-6 0 ng/ml, 100 ± 8.0%; IL-6 0.01 ng/ml, 99 ± 10.1%) and SW480^IL-6R-ND2 (Absorbance value of CCK-8; IL-6 0 ng/ml, 100 ± 4.65%; IL-6 0.01 ng/ml, 90 ± 4.4%), although the treatment suppressed proliferation of SW480^mock (Absorbance value of CCK-8; IL-6 0 ng/ml, 100 ± 9.3%; IL-6 0.01 ng/ml, 84 ± 7.6%; P < 0.01). All these qRT-PCR experiments were performed in triplicate and all these cell proliferation assays were performed in 10 wells. *P < 0.05, **P < 0.01