The HIF axes in cancer: angiogenesis, metabolism, and immune-modulation.

The hypoxia-inducible factors (HIFs) are central transcriptional mediators of the cellular response to hypoxia. HIF activation typically drives a physiologically beneficial adaptive response to hypoxia. However, within solid tumors, the HIF-driven adaptation to hypoxia results in alterations within major cancer cell signaling axes, including those regulating angiogenesis, metabolism, and immune modulation, which profoundly impact tumor progression. This review describes established and recent findings of the role of HIFs in the regulation of these major axes, and the impact of the 'HIF axes' on tumor progression and response to therapy. Current and emerging therapies targeting these axes will also be discussed.