Hypoxia-inducible factor-1 (HIF1) is a transcription factor found in mammalian cells cultured under reduced oxygen tension th at plays an essential role in cellular and systemic homeostatic responses to hypoxia. HIF1 is a heterodimer composed of an alpha subunit and a beta subunit. The beta subunit has been identified as the aryl hydrocarbon receptor nuclear translocator (ARNT). This gene encodes the alpha subunit of HIF-1. HIF-1α contains two transactivation domains located between amino acids 531 and 826. Overexpression of a natural antisense transcript (aHIF) of this gene has been shown to be associated with nonpapillary renal carcinomas. Two alternative transcripts encoding different isoforms have been identified. Specific disruption of the HIF-1 pathway is important for exploring its role in tumor biology and developing more efficient weapons to tre at cancer. HIF-1alpha is a master regulator of the hypoxic response, and its proangiogenic activities include, but are not limited to, regulation of vascular endothelial growth factor (VEGF). HIF-1alpha protein expression often seen in invasive breast cancer. Recent data demonstrates th at HIF-1alpha knockdown reduces tumorigenicity of MCF-7 cells and suggest a promising combination of both anti-HIF-1 strategy and traditional chemotherapy to improve cancer treatment.
