Bioactive Vitamin D Attenuates MED28-Mediated Cell Growth and Epithelial–Mesenchymal Transition in Human Colorectal Cancer Cells

Figure 1

Calcitriol reduced the expression of MED28, PCNA, β-catenin, c-Myc, and cyclin D1 but upregulated the expression of E-cadherin in the subcutaneous HT29 xenografts. Four-week-old male NOD/SCID mice were subcutaneously implanted with human colorectal cancer HT29 cells to their flank regions, and these animals were then randomly allotted into three groups, vehicle control (0 μg) or calcitriol (0.5 μg or 1 μg), with four mice in each group. Two weeks later, the animals were intraperitoneally administered with the assigned dose, 0 μg (vehicle), 0.5 μg, or 1 μg of calcitriol every other day. The animals were sacrificed after 4 weeks. (a) Representative images and densitometric quantification for the relative protein expression of the xenografts. The expression levels of E-cadherin, MED28, PCNA, β-catenin, c-Myc, and cyclin D1 in the xenografts, along with loading controls, were detected by Western blotting. The ratios below the images (left panel) indicate the relative expression of the specific proteins with respect to those of 0 μg after normalization with the expression of the corresponding loading controls, β-actin or α-tubulin. Densitometric data (right panel) are expressed as , ; , , , and as compared with 0 μg; , , , and as compared with 0.5 μg. (b) Tissue sections of the xenografts were subjected to immunohistochemical analysis with anti-MED28 antibodies followed by secondary antibodies and diaminobenzidine staining. Brown-colored immunostaining was observed under Nikon (Eclipse 50i) light microscope at 400× and photographed.

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