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Effect of Watermelon Powder Supplementation on Azoxymethane‐Induced Colon Carcinogenesis in Rats
Author(s) -
Glenn Keith,
Klarich DawnKylee S,
Figueroa Arturo,
Hooshmand Shirin,
Kern Mark,
Hong Mee Young
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.790.25
Subject(s) - azoxymethane , aberrant crypt foci , citrulline , nitric oxide , colorectal cancer , arginine , medicine , carcinogenesis , carcinogen , gastroenterology , endocrinology , food science , cancer , chemistry , biochemistry , colonic disease , amino acid
Colorectal cancer (CRC) is a public health concern and one of the most common cancers in men and women globally. Given the substantial morbidity and mortality associated with this disease, methods for prevention, in part through a diet high in fruits and vegetables, are under investigation. Specifically, watermelon may be a practical method for reducing CRC risk factors due to its high concentration of L‐citrulline, a precursor to L‐arginine, which plays a crucial role in endothelial nitric oxide (NO) production. Evidence suggests that increased levels of NO have tumoricidal effects; therefore, the purpose of this study was to determine the effects of watermelon powder supplementation on aberrant crypt foci (ACF) formation, precancerous lesions, and biomarkers that are associated with colon carcinogenesis in rats. Thirty‐two male Sprague‐Dawley rats, at 21 days old, were divided into three groups: control, 0.36% L‐arginine, or 0.5% watermelon powder. The 0.5% watermelon powder diet provided 0.36% of L‐arginine+L‐citrulline. Rats were injected subcutaneously with azoxymethane (dose of 15 mg/kg body weight), a carcinogenic agent, at the beginning of weeks 3 and 4. The watermelon group exhibited higher blood NO levels compared to the control group (P < 0.05). Both the L‐arginine and watermelon powder groups exhibited lower total numbers of ACF and high multiplicity aberrant crypt foci (HMACF, > 4 aberrant crypts/focus) (P < 0.01). The watermelon powder group exhibited lower 8‐hydroxyguanosine DNA damage in the blood (P < 0.05) compared to controls. Watermelon powder and L‐arginine downregulated 8‐oxoguanine DNA glycosylase (OGG1) gene expression (P < 0.05) and upregulated O 6 ‐methylguanine DNA methyltransferase (MGMT) gene expression (P < 0.01). Cyclooxgenase‐2 (COX‐2) gene expression in the colon mucosa of the watermelon group was lower compared to the control group (P < 0.05). These results suggest that watermelon powder or L‐arginine consumption may reduce the risk of colon cancer by suppressing ACF formation through lowering oxidative DNA damage and inflammation, modulating DNA repair enzyme expression, and enhancing NO production. Support or Funding Information The study was funded by The US National Watermelon Promotion Board.