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Abstract:

<p><b>BACKGROUND: </b>Hypoxia inducible factor-1 (HIF-1) plays a critical role in angiogenesis during vascular development. The authors tested the hypothesis that HIF-1 expression correlates with progression and angiogenesis in brain tumors.</p><p><b>METHODS: </b>The authors investigated the expression of the HIF-1alpha and HIF-1beta subunits in human glioma cell lines and brain tumor tissues using Western blot analysis and immunohistochemistry.</p><p><b>RESULTS: </b>In glioblastomas multiforme (GBMs), HIF-1alpha primarily was localized in pseudopalisading cells around areas of necrosis and in tumor cells infiltrating the brain at the tumor margin. In contrast, HIF-1alpha was expressed in stromal cells throughout hemangioblastomas (HBs). Like HIF-1alpha, HIF-1beta was most highly expressed in high grade tumors but was expressed more widely than HIF-1alpha, including cells away from necrotic zones. In the brains of mice injected with Glioma 261 cells, a pattern of HIF-1alpha expression identical to that observed in human GBMs was noted.</p><p><b>CONCLUSIONS: </b>In GBMs, the heterogeneous pattern of HIF-1alpha expression appears to be determined at least in part by tissue oxygenation, whereas in HBs the homogeneous expression of HIF-1alpha may be driven by an oncogenic rather than a physiologic stimulus.</p>