Cobalt chloride, a chemical inducer of hypoxia-inducible factor-1α in U251 human glioblastoma cell line

Tumor hypoxia has been described to increase the resistance of cancer cells to radiation therapy and chemotherapy. Hypoxia-inducible factor-1 alpha (HIF-1 alpha) is the main transcriptional factor activated by hypoxia and it plays a key role in reprogramming tumor growth. We examined in this study whether cobalt chloride induce HIF-1 alpha in different concentrations. U251 human glioblastoma cell line was incubated at 16 h under normoxia with or without CoCl2 at 1, 5, 10, 20, 25, 50, 100, 150 and 200 mu M treatments. In proliferation assay, CoCl2 have shown an increase in cellular induction between 50 and 200 mu M, proportionally. CoCl2 have also shown at 50 mu M the maximum induction effect. In addition, CoCl2 at 50 mu M displayed maximum response at 20,000, 30,000 and 40,000 U251 cells, respectively. In HIF-1 expression assay. CoCl2 increases HIF-1 alpha gene expression between 50 and 200 mu M. Western analysis revealed sharp protein band at 118 K Da which represented the HIF-1 alpha protein with high band density at 50 mu M CoCl2. The present paper reports the adaptive response of human glioblastoma cells to CoCl2, a chemical hypoxia-mimicking agent. The effects of the treatment were evaluated on cell proliferation, and HIF-1 alpha gene expression. (C) 2010 King Saud University. All rights reserved.