Fig. 1: SP1 and TUG1 are abundant in CRC and SP1 up-regulates the expression of TUG1 by binding to the promoter region of TUG1.

A TUG1 expression in the CRC and adjacent normal tissues (n = 20) determined by RT-qPCR. B TUG1 expression in normal human colonic epithelial cell line FHC and CRC cell lines HCT116 and SW480 determined by RT-qPCR. C SP1 protein level in the CRC and adjacent normal tissues (n = 20) measured by Western blot assay. D SP1 protein level in the human normal colonic epithelial cell line FHC and CRC cell lines HCT116 and SW480 measured by Western blot assay. E SP1 mRNA expression in the HCT116 and SW480 cells transfected with si-SP1-1, si-SP1-2 and si-SP1-3 determined by RT-qPCR. F SP1 protein level in the HCT116 and SW480 cells transfected with si-SP1-1, si-SP1-2, and si-SP1-3 measured by western blot assay. G The binding sites of SP1 in the TUG1 promoter region predicted by the JASPAR website. H After truncation of binding sites, the specific binding site 5 of SP1 in the TUG1 promoter region was determined by dual-luciferase reporter assay. I The binding of SP1 to the TUG1 promoter region with site 5 mutated analyzed by dual-luciferase reporter assay. J Binding of SP1 to the TUG1 promoter region at site 5 confirmed by ChIP assay. K Correlation between SP1 expression and TUG1 expression in clinical CRC tissue samples (p = 0.016). ^*p < 0.05, ^**p < 0.01, ^***p < 0.001 and ^****p < 0.0001, compared with adjacent normal tissues, FHC cell line, or HCT116 and SW480 cells transfected with si-NC or incubated with anti-IgG antibody. The measurement data are expressed as mean ± standard deviation. The experiments were repeated three times independently. Comparison between CRC tissues and adjacent normal tissues was conducted using paired t-test while between the other two groups by unpaired t-test. Multi-group comparison was conducted by one-way ANOVA with Tukey’s post hoc test.