_ Anti-Cancer Effects of Chinese Red Yeast Rice beyond Monacolin K alone in Colon Cancer Cells Mee Young Hong,* Navindra P. Seeram, Yanjun Zhang, and David Heber Center For Human Nutrition, David Geffen School of Medicine, University of California, Los Angeles, 90095, USA
Chinese Red Yeast Rice (RYR) is a food herb made by fermenting Monascus purpureus Went yeast on white rice. RYR contains a mixture of monacolins, one of which, Monacolin K (MK), is identical to lovastatin. Epidemiological studies show that individuals taking statins have a reduced risk of colon cancer. In the present study, lovastatin decreased cellular proliferation (P<.001) and induced apoptosis (P <.05) in HCT-116 and HT-29 human colon cancer cells. RYR inhibited both tumor cell growth (P <.001) and enhanced apoptosis (P <.05) in HCT-116. The inhibition of proliferation was reversed by mevalonate in lovastatin-treated cells, since lovastatin is a 3-hydroxy-3-methyl-glutaryl CoA reductase (HMGCR) inhibitor. However, RYR with mevalonate did not reverse the observed inhibition of growth. MK-free RYR did not reverse the observed lovastatin-mediated inhibition of cancer cell growth These observations suggest that other components in RYR, including other monacolins, pigments, or the combined matrix effects of multiple constituents may affect intracellular signaling pathways differently than purified crystallized lovastatin in colon cancer cells. RYR was purified into two fractions: pigment-rich (PF-RYR) and monacolin-rich (MF-RYR) fractions. The effect of MF-RYR was similar to that of lovastatin, while the effect of PF-RYR was similar to that of the whole RYR extract in proliferation, apoptosis and mRNA level of HMGCR and sterol response element binding protein-2. These results suggest that matrix effects of RYR beyond MK alone may be active in inhibiting colon cancer growth. RYR with/without MK may be a botanical approach to colon cancer chemoprevention worthy of further investigation.