Rye bran and soy protein delay growth and increase apoptosis of human LNCaP prostate adenocarcinoma in nude mice

BACKGROUND. In this study, we investigated whether dietary intervention cou ld inhibit tumor growth of an androgen-sensitive human prostatic cancer. METHODS. LNCaP cells were transplanted subcutaneously in nude-mice. The ani mals were then put on different diets and tumor take, tumor growth and pros tate specific antigen (PSA) secretion were studied during 9 weeks. RESULTS. Palpable tumors developed in 75% of the tumor-cell injected sites in animals fed a control diet (corn starch, sucrose, etc.) whereas, for ani mals given rye bran (RB), ethyl acetate extraction from rye bran supplement ed cellulose based diets (CCEE), palpable tumors were seen in only 30% and for soy protein based diets (SCC) 50% of the transplantation sites, respect ively. The tumors that grew to palpable size in the rye (RB) and soy (SCC) groups were smaller and secreted less PSA than those in the control group. In the rye and soy groups tumor cell apoptosis was increased, but cell prol iferation was unaffected. Addition of fat to the rye diet reduced its effec t on prostate cancer growth. CONCLUSIONS. Factors in rye bran and soy protein may inhibit prostate cance r growth. The effect is more apparent for rye than for soy. Further studies are needed to identify the effective substances and to explore the mechani sm of action. Prostate 42:304-314, 2000. (C) 2000 Wiley-Liss, Inc.