Effect of hypoxia-inducible factor 1-alpha (HIF-1 alpha ) on proliferation and apoptosis of adrenocorticotropic hormone (ACTH)-secreting pituitary adenoma cells

• Published in: African journal of biotechnology 2011-07, Vol.10 (38), p.7510-7517
• Main Authors: Pan, S, Pei, B, Zhang, C-R, Fan, C, Bian, L-G, Sun, Q-F
• Format: Article
• Language: English
• ISSN: 1684-5315; 1684-5315

To understand whether hypoxia-inducible factor 1-alpha (HIF-1 alpha ) could protect AtT-20 cells from hypoxia induced apoptosis, we investigated the effects of HIF-1 alpha on proliferation and apoptosis of adrenocorticotropic hormone (ACTH)-secreting pituitary adenoma cells (AtT-20 cells). AtT-20 cells were treated with various concentrations of CoCl sub(2) to induce hypoxia. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, a yellow tetrazole (MTT) was applied to detect the proliferation of these cells. Western blot assay and real time polymerase chain reaction (PCR) were used to determine the protein and mRNA expressions of HIF-1 alpha , respectively. In addition, AtT-20 cells were transfected with siRNA targeting HIF-1 alpha and treated with different concentrations of CoCl sub(2). The transfection efficacy was assessed by real-time PCR and western blot assay. Apoptosis was measured by fluorescein isothiocyanate (FITC)-annexin V/propidium iodide (PI) staining and TUNEL staining. The effect of CoCl sub(2) on the proliferation of AtT-20 cells was in a concentration and time dependent manner. When the concentration of CoCl sub(2) was less than or equal to 100 mu M and/or duration of CoCl sub(2) treatment was less than or equal to 48 h, CoCl sub(2) triggered the proliferation of AtT-20 cells. Nevertheless, the apoptosis rate of cells transfected with HIF-1 alpha -siRNA was markedly increased after CoCl sub(2) treatment. These findings suggest that, HIF-1 alpha can promote the proliferation of AtT-20 cells and exert anti-apoptotic effect under hypoxic condition.