Figure 1.

Benzylidene-thiazolidine-2,4-diones inhibit Pim kinase activity and prostate cancer and leukemic cell growth. A, structures of 4a and 16a. B, dose-dependent inhibition of Pim-1 kinase activity by 4a. Recombinant Pim-1 activity was measured as described in Materials and Methods using the full-length substrate 4E-BP1 in the presence of increasing concentrations of 4a and a fixed concentration of [γ³²P]ATP. C, 4a and 16a inhibit prostate cancer cell (PC3, DU145, and LNCaP) and leukemic cell (U937, K562, and MV4;11) growth in the presence of 10% serum. Cells were incubated for 72 h in complete medium in the presence of 5 μmol/L 4a, 16a, or DMSO (control) followed by a MTS assay (see Materials and Methods). Data are represented as the percent growth inhibition relative to DMSO. Average (SD) of 4 independent assays. D, comparison of the inhibitory effect of 4a and 16a in 10% serum-containing medium versus serum-free medium. PC3 or DU145 cells were plated in 10% serum-containing medium and allowed to attach for 24 h. Medium was then replaced with serum-free medium and 5 μmol/L 4a, 16a, or DMSO (control) was added and cells were incubated for an additional 72 h. Data are represented as in C.