Ascites derived from ovarian cancer-bearing mice increases chemo-resistance of ID8 cells.

<p>Murine ovarian cancer cells (ID8) from three different sources were studied: 1) ID8 cells from normal culture medium (Medium), 2) ID8 cells freshly isolated from ascites fluid in a syngeneic model (<i>In vivo</i> cells), and 3) ID8 cells treated for 7 days <i>in vitro</i> with ascites supernatant (Ascites treated 7 days). Each of these cell populations was exposed to paclitaxel<b>(A)</b> or docetaxel<b>(B)</b> at the indicated concentration for 24 h and [³H]-thymidine incorporation was determined. Three independent experiments were performed and a representative result is shown. Error bar represents SD of quadruplicates in each condition. * indicates p<0.05, *** p<0.001, Two way ANOVA. <b>A</b>. ID8 cells pre-treated with acellular ascites for 7 days (Ascites treated 7 days) or isolated from ascites (<i>in vivo</i> cells) have increased resistance to Paclitaxel compared to ID8 cells from normal medium. <b>B</b>. ID8 cells pre-treated with acellular ascites for 7 days (Ascites treated 7 days) have increased resistance to docetaxel at 2 and 4 nM compared to ID8 cells from normal culture. ID8 cells isolated from ascites (<i>in vivo</i> cells) have increased resistance to docetaxel compared to ID8 cells from normal medium (Medium). <b>C-D</b>. 7-AAD uptake was measured by flow cytometric analysis. The percent 7-AAD positive cells from three independent experiments is shown for paclitaxel (<b>C</b>) and docetaxel (<b>D</b>)-treated cells. Error bars represent SD. * indicates p<0.05, ** p<0.01, *** p<0.001, Two way ANOVA. ID8 cells pre-treated with acellular ascites for 7 days (Ascites treated 7 days) are more resistant to chemotherapy-induced cell death (<i>i</i>.<i>e</i>.,exhibit fewer 7-AAD+ cells) than ID8 cells from normal culture.