Fig. 3: Reconstitution of B55α is toxic in PC3 and DU145 cells and inhibits transformation and tumorigenicity in SCID mice by inducing mitotic arrest.

a-d Limited ectopic expression of B55α via lentiviral transduction a blocks proliferation (green dashed line shows end of Puromycin selection), b induces cell death and apoptosis, c results in a senescence-like flat cell morphology with large nuclei, and d suppresses tumor xenograft growth in SCID mice (mean tumor size 56 days post injection was 2117.37 +/− 462.14 mm³ [mean + /− SEM] in untreated cells and not detectable for Dox-treated cells). e Limited ectopic expression of B55α causes G2/M arrest and euploidy (PI/BrdU staining). PC3 cells are near triploid. G2/M = triploid G2/M cell population. Eu G1 = hexaploid G1 cells. Eu G2/M = hexaploid G2/M cells. f–h Inducible expression of B55α in PC3 and DU145 but not immortalized normal BJ-hTERT cells induces mitotic arrest. Dox inducible F-B55α PC-3 (f), DU145 (g), and BJ-hTERT cells (h) were generated by transduction with lentiviral Tet-on vectors and selected with zeocin or puromycin in tetracycline-free media. f–h Cells were induced with Dox and collected at the indicated times. DNA content was determined by PI/FACS analysis in at least two independent experiments. Expression of Flag-B55α, B55α, cyclin B1 and loading controls was determined via western blot analysis, quantitated and represented by histogram. Western blot analyses are representative of at least two independent experiments.