4.3. Sulforhodamine B (SRB) Assay

PC-3 cells were cultured in 96-well plates in RPMI 1640 medium with 5% (v/v) FBS at a density of 3000 cells per well for 24 h. Cells of few wells were fixed with 10% trichloroacetic acid (TCA) to represent for cell numbers at the time of compound treatment (T₀). Cells in control groups were incubated in 0.1% DMSO while cells in experimental groups were treated with the indicated compound for 96 h. After the treatment, cells were fixed with 10% TCA and stained with 0.4% (w/v) SRB dissolved in 1% acetic acid. Unbound dye was washed out with 1% acetic acid. The dye that bound to proteins was solubilized with 10 mM Tris base, and the absorbance of the solution was further measured at a wavelength of 515 nm to realize the inhibition of cell growth under different treatments.