Figure 3. The generation of Ang II in hypoxic tumor cells is independent of ACE-mediated pathway.

(a) The gene expression analysis of CNE2 cells showed that only renin displayed remarkably enhanced expression in the hypoxic condition, whereas AGT (angiotensinogen) and ACE (angiotensin-converting enzyme) had similar expression levels in the hypoxic condition compared with the normoxic condition. (b) The expression of RAS components in CNE2 cells was also further verified by Western blot analysis; hypoxia-1, 5% O2 condition; hypoxia-2, 1% O₂ condition. (c) The expression of renin in CNE2 cells and 5–8F cells was significantly inhibited by siRNA-renin as detected by quantitative RT-PCR. (d) The expression of ACE in CNE2 cells and 5–8F cells was significantly inhibited by siRNA-ACE as detected by quantitative RT-PCR. (e)The suppressed expression of renin by siRNA led to the decreased Ang II levels in both normoxic and hypoxic tumor cells. (f) The suppressed expression of ACE by siRNA did not significantly decreased Ang II levels in both normoxic and hypoxic tumor cells.