Figure 4.

HIF-1 activation is required for RCC4-EV cells and sufficient for RCC4-VHL cells to confer resistance against propofol-induced cell death. (a) RCC4-EV and RCC4-VHL cells were incubated with (+) or without (−) 100 µM YC-1 for 24 h with 20% O₂ prior to analysis of the indicated mRNA levels using qRT-PCR. Fold expression was calculated relative to the values measured for RCC4-VHL cells incubated with 20% O₂. Data are expressed as the mean ± SD. Differences between results were evaluated by t-test; ^#p < 0.05 for the indicated comparison. (b) Caspase 3/7 activity in RCC4-EV and RCC4-VHL cells (n = 3), incubated with or without 50 µM propofol for 6 h, with or without 100 µM YC-1 as indicated. Differences between results were evaluated by two-way ANOVA followed by Dunnett’s test for multiple comparisons; *p < 0.05, as compared to the control cells (no treatment); ^#p < 0.05 for the indicated comparison. (c) RCC4-VHL cells were incubated with or without 100 µM nPG or 100 µM DMOG for 24 h, as indicated, prior to determination of the indicated mRNA levels by qRT-PCR. Differences between results were evaluated by one-way ANOVA followed by Dunnett’s test for multiple comparisons; *p < 0.05, as compared to the control cell population (no treatment). (d) Caspase 3/7 activity in RCC4-VHL cells (n = 3) that were exposed to the indicated treatments for 24 h prior to treatment with 50 µM propofol for 6 h. Differences between results were evaluated by two-way ANOVA followed by Dunnett’s test for multiple comparisons; *p < 0.05, as compared to the control cell population (no treatment); ^#p < 0.05 for the indicated comparison.