Figure 1.

Sphere cells from ovarian cancer cell line A2780 were cisplatin resistant. (a) The sphere was from a single A2780 cell when A2780 cell was cultured in sphere-forming conditions. The sphere was photographed using inverted microscope after the cell was seeded on 96-well suspension culture plates for 5 days. (b) A2780 cells were seeded in sphere-forming condition without (up) or with (down) 20 μM cisplatin. Five days later, the spheres were photographed using inverted microscope. (c) The ovarian cancer A2780 cells (parental cell for short) and enriched sphere-forming cells (sphere cell) were seeded in plates and treated with different concentrations of cisplatin for 48 hrs. Sphere cells reseeded with full serum media for 3 days (differentiation cell) were also treated with different concentrations of cisplatin for 48 hrs. Cell viability was determined by MTT assay. ∗∗∗, statistically significant difference between A2780 unenriched cells and enriched sphere cells treated with cisplatin (P < 0.001). (d) A2780 parental and sphere cell were treated with 20 μM cisplatin; after 48 hrs, the apoptotic cells were detected through Annexin V/PI assay. (e) Means and standard errors of total number of apoptotic cells from three experiments in Figure 1(d) were shown. ∗∗∗, statistically significant difference between A2780 unenriched cells and enriched sphere cells treated with cisplatin (P = 0.0002). Data are representative of values from three independent experiments.