uPA gene expression and regulation by dasatinib analyzed at mRNA and protein levels. (a) Differential baseline expression of uPA gene between resistant (R, in black) and sensitive (S, in red) cell lines. The x-axis values are the expression level in log2-scale. The resistant cell line expressing a high level of uPA was WPMY1 and the sensitive cell line expressing a low level of uPA was LNCaP. (b) Down-regulation of uPA mRNA level by dasatinib treatment in five sensitive cell lines. The cells were treated with 100 nM dasatinib (+D) or DMSO (Ctrl) for 48 h. The p value was 0.048 by paired t-test, indicating a significant reduction of uPA mRNA following dasatinib treatment. (c) Correlation between dasatinib-induced uPA mRNA down-regulation with the sensitivity of cell lines to dasatinib. In addition to the five sensitive cell lines, three dasatinib-resistant cell lines, 22Rv, MDAPCa2b, and VCaP, were also treated with dasatinib as in (b). The extent of uPA down-regulation by dasatinib (y-axis) was negatively correlated with the log2IC50 values (x-axis) of these eight cell lines. (d) Dose-dependent down-regulation of uPA mRNA expression in PC3 cells. Cells were treated with or without different concentrations of dasatinib for 4 or 24 h. The uPA expression level relative to control is shown on the y-axis. (e) Dose-dependent inhibition of secreted uPA protein in PC3 cells by dasatinib but not by paclitaxel. Cells were treated with different doses of dasatinib, paclitaxel or DMSO for 24 h. The amount of uPA protein secreted into the culture medium by 50,000 viable cells was assessed by ELISA assay.