# Phytoglycoproteins and Human Health: Current Knowledge and Future Applications
## 3 Bioactive Properties of Phytoglycoproteins
### Anticancer and Chemopreretive Properties  
Cancer is a growing public health challenge worldwide. The ability of synthetic or natural molecules to reduce or reverse the growth, development and spread of cancer cells in vitro or in vivo is known as anticancer activity whereas chemoprevention represents the inhibition of carcinogenesis. Anticancer agents can act by suppressing tumor initiation and progression and proliferation of cancer cells via the induction of apoptosis and cell cycle arrest. PGPs have been shown to possess anticancer and chemopreverities. For instance, in both HepG2 cells in vitro and mouse bearing hepatocellular carcinoma (H22) tumor cells, CO glycoproteins derived from seeds of _Camelia oleifera_ was reported to exhibit significant antiproliferative and anticancer activities by inducing cell cycle arrest and apoptosis [30]. Additionally, a sweet potato-derived glycoprotein (SPG-56) was shown to suppress human breast cancer (MCF-7) cell line up to 80% in an in vitro assay. Similarly, SPG-56 at 60, 120 and 240 mg/kg body weight dose-dependently induced apoptosis and inhibited metastasis in MCF-7 and mouse breast cancer (4T1-Luc) cell line-grafted female BALB/c nude mice [31]. Furthermore, a glycoprotein isolated from sweet potato (SPG-8700) was reported to significantly induce apoptosis in colorectal cancer (HCT-116) cells, indicating anti-colorectal cancer activity [32]. Based on these studies, it can be inferred that the glycoproteins sourced from _Camelia oleifera_ seeds and sweet potatoes can be further investigated as dietary agents against colorectal, breast and liver cancers. Another study conducted in 1,2-dimethylhydrazine-treated mice showed that phytoglycoproteins from stem extract of _Ullmus davidiana_ Nakai (UDP) activated the proliferating cell nuclear antigen and inhibited aberrant crypt fori in the colon, and also decreased the activities of nuclear factor-kappa B (NF-kB) and activator protein-1 (AP-1) and downstream inflammatory cytokines and enzymes [33]. Similar effects were reported for phytoglycoproteins extracted from _Solanum nigrum_ Linne (Black Nightshade or Makoi) in addition to stimulation of apoptosis by the release of cytochrome c into the cytosol, activation of caspases 8 and 3, and cleavage of poly(ADP-ribose) polymerase in cervical cancer (HeLa) cells [34]. Other cellular mechanisms have been reported for PGPs. Matrix metalloproteinase-9 (MMP-9) is an enzyme involved in angiogenesis and thus is strongly linked to tumor neovascularization and proliferation of cancer cells [35]. Thus, inhibition of the activities of MMP-9 would reduce metastasis and proliferation of cancer cells, which are desired outcomes in cancer treatment and management. Phytoglycoproteins extracted from _Stynx japonica_ Siebold and Zuccarini (SJSZ) was reported to suppressed MMP-9 activities, which caused the suppression of metastasis in hepatocellular carcinoma following intraperitoneal administration to diethylnitrosamine-treated mice [36]. Furthermore, DBD phytoglycoproteins from _Dioscora battas_ Decne at 200 mg/mL were shown enhance the activity of AP-1, a transcription factor that regulates cell proliferation and induces apoptosis in BPA-induced cellular proliferation of Chang liver cells. The phytoglycoprotein also increased the activities of catalase (CAT) and glutathione per oxidase (GPx) in the cells [10]. This suggests that the _D. batatas_-derived glycoproteins exhibited anticancer property by halting cellular proliferation, and oxidative stress. Although MMP-9 inhibition reduces cancer cell growth, cancer cell proliferation involves other players and pathways such as the phosphorylated ERK, NF-\(\kappa\)B and MAPK. PGPs are known to elicit multifaceted inhibition of these other pathways involved in cancer cell growth.