Fig. 4

Human DC-SIGNR is involved in colon cancer liver metastasis in vivo. a The impact of delivering a human DC-SIGNR expression plasmid to mouse livers via tail vein injection was determined by RT-PCR analysis. Naked human DC-SIGNR plasmid DNA was used as a positive control. β-actin served as a loading control. b The influence of the human DC-SIGNR expression plasmid was detected by a Western Blot assay. The recombinant DC-SIGNR protein acted as a positive control. c The human DC-SIGNR expression levels were observed after mice were treated with different doses of the DC-SIGNR plasmid. The human DC-SIGNR levels were determined by RT-PCR (upper panel), and the relative expression of DC-SIGNR was quantified from three triplicate experiments (lower panel). The greyscale analysis of the DC-SIGNR bands was normalized to β-actin using Gelpro 32. d RT-PCR analysis of the human DC-SIGNR expression level in mice treated with 10 μg of the plasmid for the indicated lengths of time. *P < 0.05, **P < 0.01 vs the 1 d group. e Liver tissues were taken from mice one day after injection with the DC-SIGNR plasmid or an empty plasmid via tail vein. The adhesion of LoVo cells to frozen liver sections was detected by H&E staining. The red arrow marks the adherent colon cancer cells. ***P < 0.001. f DC-SIGNR expression can significantly promote the adhesion of the three types of colon cancer cells to liver tissues from mice treated with the DC-SIGNR expression plasmid by tail vein injection compared with the control group, and the interaction can be inhibited by a DC-SIGNR antibody. The cells that had adhered to the liver tissues were counted. g Images showing representative tumors in liver and spleen (n = 4 in each group). Human DC-SIGNR could increase the potency of liver metastasis in mice compared with an empty plasmid but had no influence on the local tumor size. h Representative images of H&E and Ki67 staining of tumour tissues in liver and spleen are shown. i The graph shows the mean volume of tumors and the number of metastases in the liver. j The volume of tumors and the number of metastatic spleen foci was measured in each group. The error bars in all graphs represent SD