Natural products as potent inhibitors of hypoxia-inducible factor-1α in cancer therapy

Hypoxia is a prominent feature of tumors. Hypoxia-inducible factor-1 alpha (HIF-1 alpha), a major subunit of HIF-1, is overexpressed in hypoxic tumor tissues and activates the transcription of many oncogenes. Accumulating evidence has demonstrated that HIF-1 alpha promotes tumor angiogenesis, metastasis, metabolism, and immune evasion. Natural products are an important source of antitumor drugs and numerous studies have highlighted the crucial role of these agents in modulating HIF-1 alpha. The present review describes the role of HIF-1 alpha in tumor progression, summarizes natural products used as HIF-1 alpha inhibitors, and discusses the potential of developing natural products as HIF-1 alpha inhibitors for the treatment of cancer.