Anti-tumor activities and apoptotic mechanism of ribosome-inactivating proteins

Ribosome-inactivating proteins （RIPs） belong to a family of enzymes that attack eukaryotic ribosomes and potently inhibit cellular protein synthesis. RiPs possess several biomedical properties, including anti-viral and anti-tumor activ ties. Multiple RIPs are known to inhibit tumor cell proliferation through inducing apoptosis in a variety of cancers, such as breast cancer, leukemia/lymphoma, and hepatoma. This review focuses on the anti-tumor activities of RIPs and their apoptotic effects through three closely related pathways： mitochondrial, death receptor, and endoplasmic reticulum pathways.