Figure 6

Pharmacological regulation of survivin expression in TSC2^−/− A⁺ cells. The cells were cultured for 48 h in standard medium, or in the same medium in the presence of IGF-1 (50 ng/mL), LY294002 (LY, 100 µM), PD98059 (PD, 30 µM) or anti-EGF receptor antibody (C225, 5 µg/mL). A: Survivin expression was triggered by IGF-1 and all of the other agents. The action of IGF-1 was enhanced by the co-administration of any of the other agents. The IGF-1-mediated attenuation of Smac/DIABLO expression was counteracted only by anti-EGFR. B: Survivin and Smac/DIABLO expression evaluated by means of Western blotting after two and five days’ exposure to anti-EGFR (C225, 5 µg/mL) or rapamycin (Rapa, 5 ng/mL). OD quantification showed that the expression of survivin decreased over time, whereas that of Smac/DIABLO did not. ^○○○ P< 0.001 vs. two days of anti-EGFR treatment; *** P < 0.001 vs. two days of rapamycin treatment. C: A total of 50 × 10⁴ cells were plated and counted 48 h later in a modified Neubauer chamber. Rapamycin and anti-EGFR inhibited cell proliferation (the horizontal line represents cell number at plating); the other agents had no effect, and the rate of cell growth was the same as under control condition. Despite their different effects on cell proliferation (white bars), all of the treatments enhanced survivin expression (black bar).