Figure 4: Effect of the combined treatment with melatonin and dichloroacetate (DCA) in P19 embryonal carcinoma
stem (CSCs) and differentiated (dCCs) cells, grown in glucose (Glu) and galactose (Gal) media. A. The sulforhodamine
B (SRB) assay shows a decrease in cell mass after 72 hours of the combined treatment of the Glu-CSC group with 1 mM melatonin
and 10 mM dichloroacetate. Data represent the average percentage of SRB absorbance with respective time 0 ± SEM from at least four
independent experiments. B. Content of pyruvate dehydrogenase (PDH) and PDH-subunit E1α phosphorylated at Ser293 site in the four
types of P19 cells studied reveals that melatonin was only able to contribute to dichloroacetate effect by reducing PDH phosphorylation in
Gal-dCCs. Treatments: control (C), melatonin 1 mM (M), dichloroacetate 10 mM (D), and melatonin 1 mM + dichloroacetate 10 mM
(M+D). Ponceau S was used to normalize sample loading. Bar charts show means of normalized optical density (O.D.) expressed as
percentage of control ± SEM from three separate immunoblots. *p < 0.05; **p < 0.01; ***p < 0.001 vs. control.