Kurozu moromimatsu inhibits tumor growth of Lovo cells in a mouse model in vivo

Objective In Japan, rice vinegar that has been matured and fermented for years in earthenware jars is considered a health food with anticolon cancer action. It is divided into the liquid component (Kurozu) and the sediment (Kurozu moromimatsu), which contains large amounts of organic materials and minerals. The effect of Kurozu moromimatsu (Kurozu-M) on cancer has not yet been examined. In this study, we examined the activity of Kurozu-M on colon cancer and investigated the mechanisms involved, focusing on active oxygen generation, apoptosis, and metalloproteinases (MMPs). Methods We used Lovo cells transplanted into nude mice as an experimental model. We measured the tumor volume and MMP levels and conducted hematoxylin-eosin staining (for polymorphonuclear leukocytes), terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling staining (for apoptosis), and immunostaining for nitrotyrosine (a marker of active oxygen generation) in control, Kurozu-treated, and Kurozu-M—treated groups. Results The tumor volume was the same in the control group (231 ± 36 mm3) and Kurozu group (238 ± 52 mm3), but was significantly reduced in the Kurozu-M group (152 ± 28 mm3, P < 0.001 versus control). Apoptosis of tumor cells and accumulation of polymorphonuclear leukocytes were not observed. Nitrotyrosine production, total MMP levels, and MMP activation were significantly reduced in the Kurozu-M group. Conclusion The administration of Kurozu-M prolonged the lifespan of cancer cell–transplanted mice, inhibited tumor progression, and reduced nitrotyrosine production and MMP activation, but did not induce apoptosis.