Involvement of Met receptor pathway in aggressive behavior of colorectal cancer cells induced by parathyroid hormone-related peptide

Figure 3 Parathyroid hormone-related peptide modulates Met activation through the mitogen-activated protein kinase signaling pathway in HCT116 cells. Cells were treated with PD-98059 or SB-203580, a selective mitogen-activated protein kinase (MAPK) kinase (MEK) or P38 MAPK inhibitor, respectively, for 30 min and then exposed to 10^-8 mol/L PTHrP for 1 h to evaluate whether ERK1/2 MAPK and/or p38 MAPK mediate the effect of PTHrP on Met activation in HCT116 cells. Controls were run by adding an equivalent volume of dimethylsulfoxide, the vehicle of the inhibitors. The protein levels of Met phosphorylated in the residues Tyr1234 and Tyr1235 were assessed by Western blot. These phosphorylation sites constitute activating domains of the receptor. GAPDH protein levels were determined as a control of the amount of proteins present in the membrane, since this protein is not substantially modified with the treatment by the cytokine. Graph bars represent the average of the results obtained from three independent experiments. DMSO: Dimethylsulfoxide; GAPDH: Glyceraldehyde 3-phosphate dehydrogenase; Met: Receptor tyrosine kinase Met; p-Met: Phospho-Met (Tyr1234/1235); PTHrP: Parathyroid hormone-related peptide. ^aP < 0.05.