Chemopreventive effects of polyphenol-rich extracts against cancer invasiveness and metastasis by inhibition of type IV collagenases expression and activity

Natural polyphenols, frequently called secondary metabolites, play an important role in cancer prevention and treatment. Polyphenols are characterized by high structural diversity, which translates into a very wide therapeutic spectrum, including antioxidant, anti-inflammatory, proapoptotic, anti-angiogenic and anti-metastatic activities. These compounds can modulate the activities of some functional proteins and enzymes, such as matrix metalloproteinases, including type IV collagenases (MMP-2 and MMP-9). Type IV collagenases are able to degrade the protein components of the extracellular matrix and play key roles in physiological processes, such as tissue repair and morphogenesis, as well as in carcinogenesis and other pathological processes. This review discusses the current state of knowledge concerning the anti-invasion and anti-metastatic potential of natural polyphenol-rich extracts, with a focus on in vitro and in vivo evidence. Based on these findings, plant extracts may be a promising alternative strategy to synthetic MMP-2/-9 inhibitors of cancer invasiveness and metastasis.