Fig. 8

Chronic degradation of HIF-1α attenuates invasive and angiogenesis properties of cancer cells under hypoxic conditions. (A-D) Invasion activity of HeLa and HT1080 cells growing under acute and/or chronic hypoxia over 9 and/or 24 h, respectively, was determined using a matrigel invasion chamber (A). Invasion activity under chronic hypoxia was determined in the absence and presence of either pyruvate alone or together with SIRT1-siRNA (B) or in the presence of Myc-tagged SIRT1(C) or sh-SIRT1 alone or in combination with HIF-1 (D). SIRT1 depletion was achieved with three different SIRT1-siRNAs (lower panel, B). Invasion activity of HeLa cells with sh-control (-) or sh-SIRT1 (+) plasmid was determined after transfection of either Flag-tagged HIF-1α (+) or empty vector (-). (E and F) Angiogenic activity of HeLa cells growing under acute and chronic hypoxia over 9 and 24 h, respectively, was determined by measuring tube length of HUVEC cells in the absence and presence of either pyruvate alone or together with SIRT1-siRNA (+) or control-siRNA (-) (F). (G-J) The amounts of MMP9 and VEGF proteins secreted into culture medium were determined in HeLa cells growing under hypoxia over 9- and 24-h in the absence and presence of pyruvate. The concentration of pyruvate was 0.05 mM. Statistical significance (p-value) was determined using the ANOVA-t-test. * : p < 0.05, ** : p < 0.01, *** : p < 0.001