Silencing hypoxia-inducible factor-1α inhibits cell migration and invasion under hypoxic environment in malignant gliomas

  • Authors: Satoshi Fujiwara, Kou Nakagawa, Hironobu Harada, Shigeyuki Nagato, Koji Furukawa, Mikio Teraoka, Toshimoto Seno, Keizo Oka, Shinji Iwata, Takanori Ohnishi
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  • Published online on: Sunday, April 1, 2007
  • Pages: 793-802
  • DOI: 10.3892/ijo.30.4.793

Abstract

alignant gliomas are characterized by active invasiveness, necrosis, and vascular proliferation. These pathological features have been speculated to be caused by tissue hypoxia. Hypoxia-inducible factor-1 (HIF-1), which is controlled by rapid stabilization of the HIF-1α subunit, is a pivotal transcriptional factor in the cellular response to hypoxia. Although many studies have described the relationship between tumor angiogenesis and hypoxic environment, the roles of HIF-1 in cell invasion have been barely elucidated in malignant gliomas. We investigated the role of HIF-1α in the motile and invasive activities of human glioma cells under hypoxia. Four malignant glioma cell lines, U87MG, U251MG, U373MG, and LN18, were cultured under 21 and 1% oxygen concentration. Expression of HIF-1α under hypoxia was observed to be much higher than that under normoxia in all cell lines. Introducing HIF-1α-targeted small interfering RNA (HIF-1α siRNA) into the glioma cell lines resulted in downregulation of HIF-1α expression, and significantly suppressed glioma cell migration in vitro. Furthermore, invasiveness was significantly reduced in the cells transfected with HIF-1α siRNA compared with those transfected with the control siRNA. Co-culture of glioma spheroids and rat brain slices showed that HIF-1α siRNA-transfected glioma cells failed to invade the surrounding normal brain tissue in an organotypic brain slice model. These effects of HIF-1α siRNA were more conspicuous under hypoxia than under normoxia. In addition, under hypoxic conditions, the level of matrix metalloproteinase (MMP)-2 mRNA was upregulated, and that of tissue inhibitor of metalloproteinase (TIMP)-2 was downregulated in all glioma cell lines. Treatment with HIF-1α siRNA resulted in downregulation of MMP-2 mRNA and upregulation of TIMP-2 mRNA. Furthermore, the enzyme activities of MMP-2 and MMP-9, both of which were activated by hypoxia, decreased with the introduction of HIF-1α siRNA. These findings suggest that overexpression of HIF-1α induced by hypoxic stress is an essential event in the activation of glioma cell motility through alteration of invasion-related molecules. Targeting the HIF-1α molecule may be a novel therapeutic strategy for malignant gliomas.
Journal Cover

April 2007
Volume 30 Issue 4

Print ISSN: 1019-6439
Online ISSN:1791-2423

2012 Impact Factor: 2.657
Ranked #31/196 Oncology
(total number of cites)

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APA
Fujiwara, S., Nakagawa, K., Harada, H., Nagato, S., Furukawa, K., Teraoka, M., Seno, T., Oka, K., Iwata, S., & Ohnishi, T. (2007). Silencing hypoxia-inducible factor-1α inhibits cell migration and invasion under hypoxic environment in malignant gliomas. International Journal of Oncology, 30(4), 793-802.
MLA
Fujiwara, Nakagawa, Harada, Nagato, Furukawa, Teraoka, Seno, Oka, Iwata, and Takanori Ohnishi. "Silencing hypoxia-inducible factor-1α inhibits cell migration and invasion under hypoxic environment in malignant gliomas." International Journal of Oncology International Journal of Oncology 30.4 (2007): 793-802.
Chicago
Fujiwara, Nakagawa, Harada, Nagato, Furukawa, Teraoka, Seno, Oka, Iwata, and Takanori Ohnishi. "Silencing hypoxia-inducible factor-1α inhibits cell migration and invasion under hypoxic environment in malignant gliomas." International Journal of Oncology International Journal of Oncology 30 no. 4 (2007): 793-802.