Background & objective: Selenium (Se), an antioxidant, is an essential trace element to human body. It can be used as an anti-aging agent and a tumor cell proliferation inhibitor. To further investigate the effect of selenium in cancer prevention, the authors observed the influence of Se-rich rice extract on the transformation of umbilical blood B lymphocytes stimulated by Epstein-Barr virus (EBV) and expression of EBV early antigen(EBV-EA) in Raji cells.
Methods: (1) Se-rich rice and general rice extract (dilution of 1:4 or 1:8) were added to mixture of EBV, and then umbilical blood mononuclear cells were added. Lymphoblasts transformation test was then performed. The inhibition rate of B lymphocytes transformation was calculated. (2) Raji cells stimulated by butyrate and croton oil were incubated with Se-rich rice extract. The EBV-EA positive expression rate and the inhibition rate were counted using indirect immunological flurescence method.
Results: The transformation of umbilical blood B lymphocytes stimulated by EBV was significantly inhibited by Se-rich rice extract at a concentration of 0.11 g/ml (1:8 diluted). The inhibition rate was 83.4% (P < 0.01), which was significantly higher than that of the control rice (63.1%) (P < 0.05). Se-rich rice extract showed significant inhibition on EBV-EA in Raji cells. As the extract concentration was at 0.016 microgram/ml, 0.078 g/ml, and 0.388 microgram/ml, the inhibition rates of EA were 2.85%, 12.88%, and 20.75%, respectively.
Conclusion: The transformation of umbilical blood B lymphocytes stimulated by EB virus and expression of EBV-EA in Raji cells may be significantly inhibited by Se-rich rice extract, suggesting that Se-rich rice can be used for preventing nasopharyngeal carcinoma.