Fig. 4

Overexpression of ARG1 augments the metastatic colonization ability of cancer cells. A GFP-transfected CT26 mock control and CT26 Arg1 OE cells (2 × 10⁵) were intravenously or intrasplenically inoculated into mice. Sera and liver or lung tissues for assay were collected on day 14. B Serum l-arginine levels were evaluated by HPLC, and the mean values and SDs (n = 4, three independent experiments) are shown. C Serum arginase activity was determined by EIA, and the mean values and SDs (n = 4–5) are shown. D Metastatic colonization in the liver tissue of mice was evaluated using an in vivo imaging system on day 14. Representative images of normal liver and GFP-expressing CT26 cell-bearing livers are shown. Photon flux ratios were determined from the images of liver metastatic colonization model mice (n = 4, three independent experiments). E HE staining of liver tissue was performed 14 days after inoculation. Representative images are shown. Bars in the images represent 200 mm. F Metastatic colonization in the lung tissue of mice was evaluated using an in vivo imaging system at day 14. Representative images of normal liver and GFP-expressing CT26 cell-bearing livers are shown. Photon flux ratios were determined from images of the liver metastatic colonization model mice (n = 4, three independent experiments). G HE staining of lung tissue was performed 14 days after inoculation. Representative images are shown. Bars in the images represent 500 mm. Ratios of the tumor area relative to the total liver tissue area were calculated by the ImageJ software (E, G). The mean and SD values from four independent mice are shown