Figure 3.

Twenty-four–hour treatment of RTV inhibits glucose consumption and lactate production in U87MG cells. After RTV treatment, we measured the concentration of glucose (A) and lactate (B) in the medium, and we observed a significant decrease in glucose uptake and lactate production; this reduction indicates a significant inhibition of glycolysis. As RTV treatment reduces cell proliferation, we performed the experiment in the presence of aphidicolin at a concentration blocking cell division (1 μM) to maintain a comparable number of cells in untreated (NT) and RTV-treated (RTV) cultures (C). Histograms derived from two independent experiments; at least three wells per experiment. Asterisk indicates values from controls (P < .05 unpaired t test). Error bars indicate standard deviation. (D) Western blot analysis: AMPKα activation was demonstrated in U87MG cells by an increase in the level of threonine (T172) phosphorylation compared with control; AMPKα was activated by metabolic stress (Stress) or RTV (45 μM) treatment; IDV (500 μM) treatment did not induce AMPKα activation. Act: immunoreactivity for actin. On the right, the corresponding molecular weights are indicated (kDa). (E) Histogram representing the results of the densitometric analysis of Western blot bands of three independent experiments confirming that AMPKα activation is significantly induced by Stress or RTV but not by IDV. “a.u.” (arbitrary units) indicates differences in AMPK activation in stressed (Stress), RTV- or IDV-treated versus untreated cells. Asterisks indicate P < .05 compared with NT sample. Error bars indicate standard deviation.