Figure 1. Metabolic features and expression and activity of phosphofructokinase (PFK) in hepatocellular carcinoma (HCC) cell lines.

(A) Western blot analysis of oxidative phosphorylation (OXPHOS) and PFK in total cell extracts from HCC cells and normal liver cells. β-actin was used as a loading control. (B) O₂ consumption in the indicated cell lines (nmol O₂/million cells/min) was tested by a Clark-type oxygen electrode, which detected the concentration of dissolved oxygen in a closed chamber over time. (C,D) Normalized lactate production and 2-DG uptake in HCC cells (SMMC-7721, Hep3B, HepG2, HCC-LM3, Huh-7) and normal hepatic cells (QSG-7701 and LO2) within 24 h of culture under normoxic conditions. The lactate production was normalized to the level of LO2 cell line. (E) qRT-PCR analysis of PFK expression in HCC and normal liver cells. The mRNA expression was normalized to the level of LO2 cell line. (F) PFK activity was measured by the spectrophotometric method. PFK activity was normalized to the level of the HCC-LM3 cell line. Plotted values represent the mean ± standard error of three independent experiments (n = 3) (*P < 0.05; ⁺P < 0.01).