Figure 1. The small molecule 968 inhibits cellular transformation.

(A) Left: NIH 3T3 cells were transiently transfected with oncogenic Dbl and cultured for 14 days in 5% calf serum, while treated with different benzo[a]phenanthridinones (designated 384, 335, 968, 537, and 343) (10 μM each). Cells were fixed with 3.7% formaldehyde in PBS and stained with crystal violet for counting foci. Right: 968 was serially diluted (10, 5, 2.5, and 1.25 μM) and evaluated for its ability to inhibit focus formation.

(B) NIH 3T3 cells were stably transfected with Dbl and grown in DMEM supplemented with 1% calf serum and the indicated amounts of 968. After 6 days, the cells were counted. 100% represents the number of Dbl-transformed cells counted in the absence of 968 (27.5 × 10⁴ cells). Data represent the average of 3 experiments (± s.d.).

(C) Chemical structures of the benzo[a]phenanthridinone derivatives examined for their effects on Dbl-induced focus formation (1A and S1B).

(D) Control NIH 3T3 cells were cultured in DMEM supplemented with 10% calf serum in 6 well plates, and were either treated with 10 μM 968 or 335, or untreated. At the indicated times, the cells were counted. Data represent the average of 3 experiments (± s.d.).

(E) Photomicrographs of Dbl-transfected NIH 3T3 cells (bottom panels) and control NIH 3T3 cells (top panels) cultured in 10% calf serum and treated with either DMSO (vehicle control) or 10 μM 968.