Figure 2

Both p53 restoration and caspase-8 reconstitution are needed to sensitize etoposide-induced apoptosis in HOC313 cells. A, effects of temperature downshift on the chemosensitivity of HOC313 and Ca9-22 cells. Cells were treated with increasing doses of cisplatin or etoposide at 32.5°C (solid circle) or 37°C (open triangle) for 24 h. Cell viability was measured by WST-1 assay. The results are the means ± SD from three independent experiments. Bars, SD. The asterisk indicates a significant difference (p < 0.05) between 32.5°C and 37°C (t-test). B, effects of temperature downshift on the DNA profile of drug-treated HOC313 and HOC313/c8_3 cells. Cells treated with cisplatin (10 μg/ml) or etoposide (100 μg/ml) were incubated at 32.5°C or 37°C for 24 h, followed by LSC analysis. The horizontal and vertical axes represent the DNA content and cell number, respectively. The apoptotic cell population is indicated as a percentage of the sub-G1 fraction.