Fig. 1

Development of resistant ovarian cancer cell lines and differential gene expression. A Viability curves showing the acquired resistance of A2780 and OVCAR3 cell lines. S/R CDDP identifies ovarian cancer cell lines sensitive or resistant to cisplatin, also known as cis-diammineplatinum (II) dichloride (CDDP). Data were normalized with respect to the untreated control (100% survival) and are shown as the mean and standard deviation of at least three independent experiments. The resistance index (RI) was calculated using the half maximal inhibitory concentration (IC50) as follows: IC50-resistant/IC50-sensitive cell line. p values < 0.001 indicated a significant change in drug sensitivity (Student’s t test). B Number of genes differentially expressed for each cell line in the resistance vs. sensitivity cross-analysis (adjusted p value ≤ 0.05) are shown. The black bar represents gene overexpression in resistance (UP), and the white bar represents gene underexpression in resistance (DOWN). We identified 3637 and 2512 overexpressed genes for A2780-R and OVCAR3-R, respectively, and 3076 and 2976 inhibited genes for A2780-R for OVCAR3-R, respectively. The overall analysis by cell type identified 6686 genes differentially expressed in A2780 and 5481 in OVCAR3. *The sum of each analysis does not have a mathematical equivalence because the probes that hybridized in duplicate for the same gene were eliminated