Figure 4.

HIF-2α is not essential for hypoxia-mediated maintenance of U251 cells. (a) Expression of HIF-2α mRNA in U251 and U251SC either at normoxia or hypoxia for 24 h was evaluated by RT-PCR. (b) Expression of HIF-2α and PHD1/2/3 in U251 and U251SC either at normoxia or hypoxia for 36 h was evaluated. (c) Pretreatment with HIF-2α siRNA abrogate the hypoxia-induced increase of HIF-2α protein. (d) Pretreatment with HIF-2α siRNA could not abrogate the hypoxia-induced expansion of Nestin-positive cells. Bar=50 μm. (e) Pretreatment with HIF-2α siRNA could not abrogate the hypoxia-induced increase of colony-formation ability in U251 cells. The picture of colonies in a representative dish was taken with phase contrast microscopy. Bar=1 mm. (f) Representative FACS dot plot analysis for glioma cells showed that HIF-2α siRNA could not abrogate the hypoxia-induced increase in the number of CD133-positive cells. Cells exposed to hypoxia for 36 h were fixed and analyzed by FACS. Data are from representative experiments repeated at least three times