Decreased Growth of Human Prostate LNCaP Tumors in SCID Mice Fed a Low-Fat, Soy Protein Diet With Isoflavones

Abstract

Epidemiological studies suggest that high intake of dietary fat is a risk factor for the development of clinical prostate cancer. Soy protein has also been proposed to play a role in the prevention of prostate cancer, and one of the isoflavones in soy protein, genistein, inhibits the growth of human prostate cancer cell lines in vitro. This study was designed to evaluate whether altering dietary fat, soy protein, and isoflavone content affects the growth rate of a human androgen-sensitive prostate cancer cell line (LNCaP) grown in severe-combined immunodeficient (SCID) mice. SCID mice were randomized into four dietary groups: high-fat (42.0 kcal%) + casein, high-fat (42.0 kcal%) + soy protein + isoflavone extract, low-fat (12.0 kcal%) + casein, and low-fat (12.0 kcal%) + soy protein + isoflavone extract. After two weeks on these diets, the mice were injected subcutaneously with 1 x 10(5) LNCaP tumor cells and placed in separate cages (1 mouse/cage) to strictly control caloric intake. Isocaloric diets were given 3 days/wk, and tumor sizes were measured once per week. The tumor growth rates were slightly reduced in the group that received the low-fat + soy protein + isoflavone extract diet compared with the other groups combined (p < 0.05). In addition, the final tumor weights were reduced by 15% in the group that received the low-fat + soy protein + isoflavone extract diet compared with the other groups combined (p < 0.05). In this xenograft model for prostate cancer, there were statistically significant effects on tumor growth rate and final tumor weight attributable to a low-fat + soy protein + isoflavone extract diet.

Effect of Altering Dietary ω-6/ω-3 Fatty Acid Ratios on Prostate Cancer Membrane Composition, Cyclooxygenase-2, and Prostaglandin E2

“…The mice were found to have equal caloric intake in the n-3 and n-6 diet groups, therefore, a paired feeding regimen to match caloric intake between experimental groups was not required. Our experience has been that mice may significantly alter caloric intake depending on the palatability of the research diet, and palatability studies are therefore required prior to evaluating the effect of diets and/ or supplements on tumor progression in mice (29,34). Fig.…”

Soy isoflavone genistein in prevention and treatment of prostate cancer

“…52,53 These, and other trials with animal models provide promising data for treatment of PCa with isoflavonoids. [54][55][56][57] A compilation of the preclinical in vitro and in vivo data is shown in Table 1.…”

Inhibition of orthotopic growth and metastasis of androgen‐sensitive human prostate tumors in mice by bioactive soybean components

“…Several studies have been conducted to investigate the role of soy components on prostate cancer growth [8][9][10][11], but none on prostate cancer metastasis. Although no animal model provides all of the characteristics of the human disease, androgen-regulated growth and the potential for metastasis are two clinically important characteristics that are captured in orthotopic implant models using the SCID mouse and the LNCaP human prostate cancer cell line [12].…”