Figure 7

Efficient knockdown of RB in cancer cells increases cellular sensitivity to TAI-1. (A) MDA-MB-231 cells which carry wild-type RB were transfected with control siRNA (siControl) or siRNA of RB (siRB) for 24 hours and treated with TAI-1 (starting dose 100 μM, 3x serial dilution), incubated for 48 hours and analyzed for viability with MTS. Cellular sensitivity is expressed in GI₅₀ (nM) and RNA from transfected cells were analyzed for RB RNA level by quantitative real time PCR. SiRB reduced GI₅₀ of compound in cells. (B) Selected cell lines which carry wild type RB (MDA-MB-231, K562, ZR-75-1, T47D, A549, HCT116) or mutated RB (HeLa, as control) were transfected with siRB and treated with TAI-1, incubated for 48 hours and analyzed for viability with MTS. Cellular sensitivity is expressed as% growth inhibition and cell lysates from transfected cells were collected and RB protein levels determined by western blotting. Shown are representative results from at least two independent experiments.