FIGURE 5.

[U-¹⁴C]Pyruvate incorporation into [¹⁴C]cholesterol or ¹⁴CO₂ for tumor 3924A vs. normal liver tissue slice incubations, ± BTC. Normal liver and tumor tissue slices were incubated with [U-¹⁴C]pyruvate plus or minus 10 mM BTC, and assayed at each time interval shown. Data are given as ratios over time for ¹⁴C incorporated into sterol vs. CO₂. In addition to the clearly enhanced rate of sterol synthesis in tumor 3924A, the trend lines over time indicate that in this rapidly growing hepatoma, whose mitochondria are highly enriched in membrane cholesterol, BTC dramatically reverses the pyruvate carbon flux from sterol incorporation to CO₂ formation (see: Parlo and Coleman, 1986 for details on methods).