Figure 7.
Soluble ICAM-1 in cancer-cell conditioned medium promote osteoclast-like cell formation.
RAW264.7 cells were stained for TRAP after treatment for 6 days with 20 ng/ml RANKL [RANKLlow], or 50 ng/ml RANKL [RANKLhigh], or conditioned medium from indicated cell lines, or conditioned medium plus 20 ng/ml RANKL with ICAM-1-neutralizing antibody (ICAM-1 Ab) or control IgG, or recombinant sICAM 10 ng/ml with or without 20 ng/ml RANKL. DMEM medium was used as control medium. Control conditioned medium (conCM) was collected from indicated cancer cells without leptin treatment and activated conditioned medium (acCM) was collected from cells previously subjected to 100 ng/ml leptin treatment. Detailed method of collecting conditioned medium was describe in Materials and Methods. (a, c) Representative images and quantification of TRAP-positive osteoclast-like cells from RAW264.7 cells treated with conditioned medium collected from H292 lung cancer cells; (b, d) representative images and quantification of TRAP-positive osteoclast-like cells from RAW264.7 cells treated with conditioned medium collected from MCF7 breast cancer cells. Scale bar represents 100 μm. Graphs show mean ± SD of at least three independent experiments.
**p < 0.01; ***p < 0.001 compared with the indicated group.
##p < 0.01 compared with the indicated group.
The mRNA expression of osteoclast-specific markers NFATC (e) and TRAP (f) were also evaluated. Graphs showed mean ± SD of at least three independent experiments.
$$p < 0.01; $$$p < 0.001 compared with the ‘control medium’ group.
&&p < 0.01; &&&p < 0.001 compared with the sICAM-treated group.
**p < 0.01; ***p < 0.001 compared with the conCM-treated group.
#p < 0.05; ##p < 0.01 compared with the ‘acCM + [RANKLlow] + immunoglobulin’ group.
acCM, activated conditioned medium; conCM, control conditioned medium; DMEM, Dulbecco’s Modified Eagle Medium; ICAM-1, intercellular adhesion molecule-1; ICAM-1 Ab, ICAM-1-neutralizing antibody; IgG, normal immunoglobulin G isotype; mRNA, messenger ribonucleic acid; NFATC, nuclear factor of activated T cells; sICAM, recombinant soluble ICAM; RANKL, receptor activator of nuclear factor kappa-B ligand; [high], high concentration; [low], low concentration; SD, standard deviation; TRAP, tartrate-resistance acid phosphatase.