Article

Lack of chemoprevention of dietary Agaricus blazei against rat colonic aberrant crypt foci.

Department of Pathology, Botucatu Medical School, UNESP Sao Paulo State University, Botucatu, SP, Brazil.
Human &amp Experimental Toxicology (Impact Factor: 1.45). 07/2008; 27(6):505-11. DOI: 10.1177/0960327108091862
Source: PubMed

ABSTRACT The mushroom Agaricus blazei (Ab) has been widely used in folk medicine to treat various diseases including cancer. No information is available on its possible protective effects on the development of colon cancer. The potential blocking effect of Ab intake on the initiation stage of colon carcinogenesis was investigated in a short-term (4-week) bioassay using aberrant crypt foci (ACF) as biomarker. Male Wistar rats were given four subcutaneous injections of the carcinogen 1,2-dimethylhydrazine (DMH, 40 mg/kg bw, twice a week), during 2 weeks to induce ACF. The diet containing Ab at 5% was given 2 weeks before and during carcinogen treatment to investigate the potential beneficial effects of this edible mushroom on DMH-induced ACF. All groups were killed at the end of the fourth week. The colons were analyzed for ACF formation in 1% methylene blue whole-mount preparations and for cell proliferation in histological sections immunohistochemically stained for the proliferating cell nuclear antigen (PCNA). All DMH-treated rats developed ACF mainly in the middle and distal colon. Agaricus blazei intake at 5% did not alter the number of ACF induced by DMH or the PCNA indices in the colonic mucosa. Thus, the results of the present study did not confirm a chemopreventive activity of Ab on the initiation stage of rat colon carcinogenesis.

0 Bookmarks
 · 
51 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: The present study evaluated the chemopreventive potential of mate tea-like intake on mammary and colon carcinogenesis initiated by 7,12-dimethylbenz(a)antracene (DMBA) and 1,2-dimethylhydrazine (DMH) in female Swiss mice. After the initiation period, the animals received basal diet and organic mate tea-like, conventional mate tea-like, or green tea (positive control) at 2.0% as the drinking fluid during 15 weeks. At week 20, colon and mammary gland were analyzed for preneoplastic and neoplastic lesions development. Colon and mammary gland complexes were processed for cell proliferation analysis, estimated by proliferating cell nuclear antigen labeling index (PCNA-LI%). Specially, organic mate tea-like reduced the values of PCNA-LI% in colonic crypts (p < .003) and in mammary glands (p < .05) in DMBA/DMH-initiated groups. A lower incidence of aberrant crypt foci (ACF) in colon (p = .03) and of hyperplastic and neoplastic lesions in mammary gland (p < .05 and p < .02, respectively) was observed in DMBA/DMH-initiated groups treated with organic mate tea-like. These results suggest that post-initiation treatment with organic mate tea-like inhibited the development of colon and mammary carcinogenesis in a two-step medium-term mouse carcinogenesis model.
    Human & Experimental Toxicology 01/2010; · 1.31 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Asclepias curassavica Linn. is a traditional medicinal plant used by tribal people in the western ghats, India, to treat piles, gonorrhoea, roundworm infestation and abdominal tumours. We have determined the protective effect of beta-sitosterol isolated from A. curassavica in colon cancer, using in vitro and in vivo models. The active molecule was isolated, based upon bioassay guided fractionation, and identified as beta-sitosterol on spectral evidence. The ability to induce apoptosis was determined by its in vitro antiradical activity, cytotoxic studies using human colon adenocarcinoma and normal monkey kidney cell lines, and the expression of beta-catenin and proliferating cell nuclear antigen (PCNA) in human colon cancer cell lines (COLO 320 DM). The chemopreventive potential of beta-sitosterol in colon carcinogenesis was assessed by injecting 1,2-dimethylhydrazine (DMH, 20 mg/kg b.w.) into male Wistar rats and supplementing this with beta-sitosterol throughout the experimental period of 16 weeks at 5, 10, and 20 mg/kg b.w. beta-sitosterol induced significant dose-dependent growth inhibition of COLO 320 DM cells (IC50 266.2 microM), induced apoptosis by scavenging reactive oxygen species, and suppressed the expression of beta-catenin and PCNA antigens in human colon cancer cells. beta-sitosterol supplementation reduced the number of aberrant crypt and crypt multiplicity in DMH-initiated rats in a dose-dependent manner with no toxic effects. We found doses of 10-20 mg/kg b.w. beta-sitosterol to be effective for future in vivo studies. beta-sitosterol had chemopreventive potential by virtue of its radical quenching ability in vitro, with minimal toxicity to normal cells. It also attenuated beta-catenin and PCNA expression, making it a potential anticancer drug for colon carcinogenesis.
    BMC Complementary and Alternative Medicine 01/2010; 10:24. · 2.08 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Zinc has been proposed as a promising chemopreventive candidate against colon cancer. However, few studies on the potential beneficial effects of this trace element on cancer chemoprevention are available. The present study was designed to investigate the potential modifying influence of zinc gluconate (ZnGly) on the initiation step of colon carcinogenesis induced by 1,2-dimethylhydrazine (DMH). Male Wistar rats received orally ZnGly (15 mg elemental zinc/kg, 3 times per wk) 2 wk before and during DMH treatment (3 × 40 mg/kg, once a wk). The animals were euthanized at the end of 4th and 16th wk. Colons were analyzed for aberrant crypt foci (ACF) and tumor development. Blood and colon zinc levels, cell proliferation, and apoptosis indexes in colonic crypts were analyzed 24 h after the last DMH administration. Oral treatment with ZnGly did neither alter the number of ACF nor the indexes of cell proliferation and apoptosis in the colonic mucosa. The incidence and multiplicity of colon tumors induced by DMH and their histopathological patterns were not modified by previous treatment with ZnGly. These findings indicate a lack of chemopreventive action of zinc gluconate supplementation on the initiation step of rat colon carcinogenesis induced by DMH.
    Nutrition and Cancer 01/2013; 65(4):571-7. · 2.70 Impact Factor