Hypoxia Induced by Cobalt Chloride Triggers Autophagic Apoptosis of Human and Mouse Drug-Resistant Glioblastoma Cells through Targeting the PI3K-AKT-mTOR Signaling Pathway

Figure 4

Effects of 3-methyladenine (3-MA), rapamycin (Rapa), and hypoxia-inducible factor- (HIF-) 1α knockdown on autophagy of human drug-resistant glioblastoma cells. Human temozolomide- (TMZ-) resistant U87 MG-R glioblastoma cells were selected from TMZ-sensitive U87 MG cells. (a, b) Human U87 MG-R glioblastoma cells were pretreated with 3-MA at 1 mM or Rapa at 0.5 μM for 1 h and then exposed to hypoxia for additional 24 h. Control cells received DMSO only. A flow cytometric method was carried out to quantify autophagic cells. (c) Human U87 MG-R cells were treated with HIF-1α small interfering (si) RNA (HIF siRNA) for 48 h. Scrambled siRNA was applied to control cells as the negative control (control). HIF-1α was immunodetected, and β-actin was analyzed as the internal control. These protein bands were quantified and statistically analyzed. (d) Human U87 MG-R cells were pretreated with HIF-1α siRNA and then exposed to hypoxia. Autophagic cells were quantified using flow cytometry. Data are expressed as the for . vs. control and ^# vs. U87 MG.

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