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Figure 5 | BMC Cancer

Figure 5

From: Alternating current electrical stimulation enhanced chemotherapy: a novel strategy to bypass multidrug resistance in tumor cells

Figure 5

Electrical stimulation selectively increased chemotherapeutic efficacy in drug resistant cells. (a) Doxorubicin uptake in normal human astrocytes versus MDR1 over-expressing glial cells isolated from patients with multiple drug resistant epilepsy. Note that electrical stimulation and MDR1 blockade by XR9576 (20 nM and 1 μM) significantly increased doxorubicin uptake in MDR1+ cells compared to controls while normal astrocytes were virtually unaffected as confirmed by quantitative analysis (n = 10; p = 0.017). Note that the effect of AC stimulation on Doxorubicin uptake is comparable to the effect of XR used at a final concentration of 1 μM where full MDR1 blockade was achieved. (b) Estimation of lethal concentration of doxorubicin under different experimental conditions. Normal astrocytes were virtually insensitive to electrical stimulation and MDR1 blockade by XR9576 at all concentrations of doxorubicin tested. In contrast, MDR1 expressing glial cells responded to ES or MDR1 blockade. Note that a concentration of 20 nM of XR9576 corresponds to EC50. The final concentration of XR used for the comparison (1 μM) was approximately three times higher that the concentration required to achieve full blockade of the MDR1 transporters. The asterisk indicates a significant difference (n = 10; p < 0.022 by ANOVA) from controls whereas the sign plus symbolizes significant difference (n = 10; p < 0.027) from XR-treated cultures. Data points were fitted by the following sigmoid: Equation: y = A2 + (A1-A2)/(1 + (x/x0)^).

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