FIGURE 1. FTS downregulates active Ras-GTP and its downstream signaling, leading to inhibition of cell proliferation in ECC1 and USPC1 EC cell lines.

(a) Dose-dependent decrease in the number of viable ECC1 or USPC1 cells as a function of FTS concentration. ECC1 and USPC1 cells were plated in 24-well plates, and treated after 24 hr with 0.1% DMSO (control) or FTS (100, 75, 50, or 25 μM). After 4 days the cells were counted. The IC₅₀ values of FTS in both cell lines were derived from the graph equations. (b) Immunoblots of Ras, Ras-GTP (active Ras), phospho-ERK, ERK, phospho-Akt, Akt, and β-tubulin (loading control) prepared from ECC1 and USPC1 control lysates and from lysates of ECC1 and USPC1 cells treated with 50μM FTS. ECC1 and USPC1 cells were plated in 10-cm plates and treated after 24 hr with 0.1% DMSO (control) or 50μM FTS. Three days later cells were lysed and subjected to western blotting with anti-pan-Ras, anti-Akt, anti-pAkt, anti-pERK, anti-ERK or anti-β-tubulin Abs (loading control). (c) FTS significantly decreases Ras-GTP, pERK, and pAkt both in ECC1 cells and (d) in USPC1 cells. There were no significant differences in total Ras, total ERK, total Akt or β-tubulin between control and FTS-treated cells. These results indicated that FTS acts in both cell lines as an inhibitor of active Ras and its downstream signaling. *, ** and *** are compared with the control for each cell line. *p < 0.05, ** p < 0.01, ***p < 0.001. Con, control