Overview of polyphenols and polyphenol-rich extracts as modulators of IGF-1, IGF-1R, and IGFBP expression in cancer diseases

Plant polyphenols, including polyphenol-rich extracts, display various biological activities. They have been found to act as, among others, anti-oxidative, anti-proliferative, pro-apoptotic, anti-angiogenic and anti-inflammatory agents. These compounds can modulate the activities of some functional proteins and receptors, such as insulin-like growth factor system, including IGF, IGF-1R, and IGFBPs proteins. The IGF system plays an important role in cell processes such as proliferation, differentiation and apoptosis, as well as in carcinogenesis. Plant polyphenols also have the ability to prevent the development of cancer, modulating some of the signal transduction pathways (PI3K/Akt and MAPK/ERK) associated with the process. Their variety of mechanisms of action offers hope that both individual phenolic compounds and extracts may be used for the prevention or inhibition of carcinogenesis. This review discusses the impact of natural polyphenols and polyphenol-rich extracts on the expression and activity of IGF-1, IGF-R, and IGFBP in various cancers.