Açaí Berries Inhibit Colon Tumorigenesis in Azoxymethane/Dextran Sulfate Sodium-Treated Mice

BACKGROUND/AIMS: The aim of this study was to investigate the protective effect of açaí against azoxymethane (AOM)/dextran sulfate sodium (DSS)-induced colorectal cancer development. METHODS: The effect of açaí on tumorigenesis was assessed by evaluating tumor incidence, multiplicity and invasiveness in the mouse colon. The levels of myeloperoxidase (MPO) and proinflammatory cytokines (tumor necrosis factor α [TNF-α], interleukin [IL]-1β, and IL-6) were measured via enzyme-linked immunosorbent assay. Protein levels of cyclooxygenase 2 (COX-2), proliferating cell nuclear antigen (PCNA), B-cell lymphoma 2 (Bcl-2), Bcl-2-associated death promoter (Bad) and cleaved-caspase-3 were assessed by immunoblotting. RESULTS: Administration of pellets containing 5% açaí powder reduced the incidences of both colonic adenoma and cancer (adenoma, 23.1% vs 76.9%, respectively, p=0.006; cancer, 15.4% vs 76.9%, respectively, p=0.002). In the açaí-treated mice, the MPO, TNF-α, IL-1β and IL-6 levels in the colon were significantly down-regulated. Açaí inhibited PCNA and Bcl-2 expression and increased Bad and cleaved-caspase-3 expression. In vitro studies demonstrated that açaí treatment reduced lipopolysaccharide-induced expression of TNF-α, IL-1β, IL-6 and COX-2 in murine macrophage RAW 264.7 cells. CONCLUSIONS: Açaí demonstrated protective effects against AOM/DSS-induced colon carcinogenesis, which suggests that the intake of açaí may be beneficial for the prevention of human colon cancer.

Effect of N-Methyl-N-Nitrosourea on Helicobacter-induced Gastric Carcinogenesis in C57BL/6 Mice

BACKGROUND: The aim of this study was to investigate the effect of N-methyl-N-nitrosourea (MNU) treatment followed by chronic Helicobacter pylori SS1 and H. felis colonization on the stomachs of C57BL/6 mice. The role of MNU and Helicobacter species in gastric carcinogenesis was also elucidated. METHODS: A total of 69 C57BL/6 mice at 4 weeks of age were divided into 6 groups according to MNU treatment and H. pylori SS1 or H. felis infection. The mice were sacrificed at 21 and 50 weeks. The degree of inflammation was determined by histopathology. The levels of gastric mucosal myeloperoxidase, TNF-α, and interleukin-1β (IL-1β) were measured by ELISA. RESULTS: In the H. felis groups with or without MNU, the incidence of gastric tumors was 21.1% and 35.0% at 21 and 50 weeks, respectively. No gastric tumors were observed in all control mice. At 50 weeks, 37.5% of gastric adenoma cases were observed in the H. felis alone and MNU + H. felis groups. Furthermore, 12.5% of gastric adenocarcinoma cases were observed in the MNU alone and MNU + H. felis groups. The gastric mucosal IL-1β level was significantly higher in the MNU + H. felis group at 21 weeks and H. felis group at 50 weeks, respectively, than that for control mice (P < 0.05). However, the effect of MNU on H. pylori SS1-induced gastric carcinogenesis was low compared to that on H. felis. CONCLUSIONS: Administration of MNU before H. felis infection provokes severe inflammation through IL-1β, and eventually induces gastric cancer. However, the role of MNU in H. pylori SS1-induced gastric carcinogenesis model is minor.

Gastroprotective Effects of PMK-S005 against Ethanol-Induced Acute Gastric Damage in Rats

BACKGROUND/AIMS: This study aimed to examine the gastroprotective effects of PMK-S005, which is a synthetic S-allyl-L-cysteine (SAC; a sulfur-containing amino acid), against acute ethanol-induced gastric damage in rats. METHODS: Sprague-Dawley rats were divided into six groups, including a nonethanol group, groups treated with absolute ethanol 1 hour after pretreatment with various doses of PMK-S005 (1, 5, and 10 mg/kg) or rebamipide (50 mg/kg), and an absolute ethanol-only group. Ethanol-induced gross ulcer and mucus levels were measured. Myeloperoxidase, tumor necrosis factor α, interleukin 1β, PGE2, LTB4, cPLA2, COX-1, and COX-2 levels were estimated by enzyme-linked immunosorbent assay or Western blot analysis. Furthermore, the protein expression levels of antioxidant enzymes, including heme oxygenase-1 (HO-1), NAD(P)H:quinine oxidoreductase 1 (NQO-1), GCLC, and GCLM, were assessed. RESULTS: PMK-S005 significantly attenuated the ethanol-induced gastric damage; it reduced mucosal inflammatory cytokine production and increased mucus levels. The expression levels of cPLA2, COX-1, and COX-2 were decreased by PMK-S005. PMK-S005 did not affect PGE2 synthesis, but LTB4 production was significantly suppressed. In addition, long-term administration of PMK-S005 significantly increased the expression of HO-1, NQO-1, GCLC, and GCLM. CONCLUSIONS: These results strongly suggest that PMK-S005 prevents gastric mucosal damage and that these gastroprotective activities are due to anti-inflammatory effects and enhancement of the gastric defense system, including antioxidant enzymes.

Anti-inflammatory and Anti-tumorigenic Effects of Açai Berry in Helicobacter felis-infected mice

BACKGROUND: The aim of this study was to evaluate the anti-inflammatory and anti-tumorigenic effect of açai berry after chronic Helicobacter felis colonization in the stomachs of C57BL/6 mice. METHODS: A total of 57 four-week-old female C57BL/6 mice (18 control mice and 39 experimental mice) were used. The mice were administered orogastrically with vehicle only or vehicle containing H. felis, 5 times every other day. After inoculation of H. felis, mice were fed either a standard or an açai-containing diet and then sacrificed at 4, 24, and 52 weeks. The infection status and degree of inflammation were determined by culture and histopathology. The level of gastric mucosal myeloperoxidase (MPO), TNF-α, and interleukin-1β (IL-1β) were measured by ELISA. RESULTS: At 24 weeks after inoculation, mucosal atrophy and mucous metaplasia appeared in all infected mice. At 52 weeks after inoculation, dysplastic change was noted in 10%, 25%, and 50% of mice in the H. felis-control, H. felis-açai 5%, and H. felis-açai 10% groups, respectively. The neutrophil, monocyte, atrophy, and metaplasia grades of infected mice showed no significant difference among the H. felis-infected groups. H. felis-infected mice fed with açai berry showed no significant difference compared with H. felis-infected control mice in gastric mucosal MPO, TNF-α, and IL-1β levels. CONCLUSIONS: H. felis that colonized the stomachs of C57BL/6 mice provoked inflammation, and induced mucosal atrophy, metaplasia, and dysplasia. However, açai berry did not effectively prohibit the gastric carcinogenesis which was induced by chronic H. felis infection.