Figure 6

ω 3PUFAs restore doxorubicin cytotoxicity in chemoresistant colon cancer cells. HT29 and HT29-dx cells were incubated for 48 h in the absence (CTRL) or in the presence of 50 μM arachidonic acid (AA), docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA). 5 μM doxorubicin (DOX) was added for 24 h, alone or during the last 24 h of incubation with fatty acids. Cycloheximide (4 μM for 24 h, CHX) was chosen as positive control of cytotoxicity in both chemosensitive and chemoresistant cells. (A) The intracellular accumulation of doxorubicin was measured fluorimetrically in duplicate. Data are presented as means ± SD (n = 3). Versus CTRL HT29: * p < 0.005; versus CTRL HT29-dx: ° p < 0.005. (B) Cells were stained with Neutral Red solution and the absorbance of viable cells was measured in triplicate spectrophotometrically. Data are presented as means ± SD (n = 4). Versus respective CTRL: * p < 0.002; versus DOX alone: ° p < 0.005. (C) Surface levels of calreticulin were measured in non-permeabilized cells by flow cytometry. The figures shown here are representative of three similar experiments, performed in triplicate. (D) The phagocytosis rate by DCs was evaluated in duplicate by flow cytometry. Data are presented as means ± SD (n = 4). Versus respective CTRL: * p < 0.05; versus DOX alone: p < 0.005.