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ARS Home » Southeast Area » Little Rock, Arkansas » Arkansas Children's Nutrition Center » Research » Publications at this Location » Publication #186817
Title: IN VITRO ACTIONS ON HUMAN CANCER CELLS AND THE LIQUID CHROMATOGRAPHY-MASS SPECTROMETRY/MASS SPECTROMETRY FINGERPRINT OF PHYTOCHEMICALS IN RICE PROTEIN ISOLATE

Author
item FANG, NIANBAI - ACNC/UAMS
item YU, SHANGGONG - ACNC/ACH
item LI, QINGLIN - ACNC/UAMS
item LUO, HONGFENG - ACNC/UAMS
item ZHANG, JIANZIANG - ACNC/UAMS
item RONIS, MARTIN - ACNC/UAMS
item BADGER, THOMAS - ACNC/UAMS

Submitted to: Journal of Agriculture and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/19/2006
Publication Date: 6/12/2006
Citation: Fang, N., Yu, S., Li, Q., Luo, H., Zhang, J., Ronis, M.J., Badger, T.M. 2006. In vitro actions on human cancer cells and the liquid chromatography-mass spectrometry/mass spectrometry fingerprint of phytochemicals in rice protein isolate. Journal of Agriculture and Food Chemistry. 54(12):4482-4492.

Interpretive Summary: Diet is believed to be one of the most important lifestyle factors responsible for lower incidence of breast and colon cancer in certain Asian countries as compared with the United States. In this study, we identified the 57 phytochemicals bound to rice protein that might be responsible for cancer protection in Asian populations that consume large amounts of rice. In addition, we determined that in rats treated with a carcinogen, those fed diets made with rice protein had significantly increased disease-free periods (tumor free) as compared with rats fed diets made with the major milk protein, casein. In addition, extracts of rice protein killed human cancer cells and/or impaired their function. Thus, rice protein, when consumed as a major part of an otherwise healthy diet, may prevent certain types of cancers.

Technical Abstract: Rice protein isolate (RPI) has been reported to reduce the incidence of 7,12-dimethylbenz[a]anthracene (DMBA)-induced mammary tumors in rats. These effects have not been replicated, nor have the factors responsible for these effects have been identified. In this study, we fed rats AIN-93G diets made with either casein (CAS) or RPI and studied chemically induced mammary cancers using the procarcinogen DMBA. We found that DMBA-treated rats fed-RPI diets had significantly increased tumor latency (P<0.05) as compared with CAS-fed control rats. To determine the potential role of phytochemicals associated with the RPI, we studied in vitro antitumor activities of an ether fraction from RPI using human tumor cell lines, including: two human breast carcinoma cell lines (MDA-MB-453 and MCF-7) and two myeloma cell lines (RPMI-8226 and IM-9). Concentration-dependent antiproliferative effects of the ether fraction were observed in all cell lines using the standard 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay. Fraction-induced apoptosis (P<0.05) was detected in all cell lines, and this was associated with the induction of pro-apoptotic bax protein and cdk inhibitors (p21) and the suppression of cdk4 and cyclin D1 activity. Liquid chromatography/mass spectrometry/mass spectrometry (LC-MS/MS) with both positive and negative modes was used to analyze the phytochemicals in the ether fraction from RPI. Fifty-seven phytochemicals were identified or characterized by their diagnostic fragmentation patterns and direct comparison with the authentic standards on the basis of electrospray ionization (ESI) MS/MS data. The major components bound to RPI were lysoglycerophospholipids (lyso-PL), fatty acids and fatty acid 3-[2-(2,3-dihydroxy-propoxycarbonyl)-2-hydroxy-ethoxy]-2-hydroxy-propyl esters (FA DPHEHP esters).