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Anticancer effect of Kalpaamruthaa on mammary carcinoma in rats with reference to glycoprotein components, lysosomal and marker enzymes.(2006-03)A promising approach to reduce the occurrence of cancer is its treatment, specifically by chemical intervention through minor dietary constituents. Epidemiological studies suggest that specific pharmacologically active agents present in the diet might reduce cancer. A remarkable surge of interest in chemoprevention research has, thus, lead to the identification of many phytochemicals of dietary origin as effective potential chemotherapeutic agents. In the present investigation, attempt has been made to study the potency of Kalpaamruthaa (KA), a herbal preparation, against cancer. The changes in level of glycoprotein components, marker enzymes and lysosomal enzymes were carried out in 7,12-dimethylbenz(a)anthracene (DMBA) induced Sprague-Dawley rats. The changes in the body weights and volume were also determined. KA was administered at the dosage level of 100, 200, 300, 400 and 500 mg/kg body weight (BW) in olive oil orally for 14 d, after the induction period is completed (90 d). On administration of KA, the levels of the above enzymes and the changes in the body weights and volume were significantly normalized in a dose dependent manner. The present study shows that KA is effective at the dosage level of 300 mg/kg body weight in mammary carcinoma bearing rats.
Atm-haploinsufficiency enhances susceptibility to carcinogen-induced mammary tumors.(2006-04)Ataxia-telangiectasia (A-T), which is due to mutations in the ATM gene, is a rare autosomal recessive genomic instability syndrome characterized by radiosensitivity and predisposition to cancer. Epidemiological studies have suggested that relatives of A-T patients (A-T carriers) have increased risks of developing breast cancer. We propose that increased breast cancer risks in A-T carriers may be due to exposure to various environmental carcinogens and/or dietary consumption. To test this hypothesis, we treated a congenic strain of Atm+/- mice with DMBA (7,12-dimethylbenz(alpha)anthracene), a mammary carcinogen, and observed mammary tumor incidence. It was found that Atm+/- mice have a 2-fold increase, as well as early onset, in mammary tumor incidence relative to wild-type mice (P<0.005). The increased mammary tumor development is correlated with a 3-fold increase in the development of mammary dysplasia in Atm+/- compared with wild-type mice (P<0.05). We also found that Ras signaling pathway was not activated in DMBA-induced mammary tumors irrespective of the Atm status. At the cellular level, Atm-haploinsufficiency confers increased cellular stress manifested by an increased p53 expression and a slightly enhanced survival of mammary epithelial cells in response to radiation. Our results demonstrate that Atm heterozygotes are predisposed to mammary tumor development and support the hypothesis that exposure to environmental carcinogens contributes to the increased rate of breast cancer development in A-T carriers. Given that 1% of the general population are ATM heterozygotes (A-T carriers), this study has great implications in breast cancer development in this population.
Dietary effects of soy isoflavones daidzein and genistein on 7,12-dimethylbenz[a]anthracene-induced mammary mutagenesis and carcinogenesis in ovariectomized Big Blue transgenic rats.(2006-10)The major constituents of isoflavones daidzein (DZ) and genistein (GE) interact with the and estrogen receptors in several tissues including mammary tissues. In this study, we used ovariectomy (OVX) to model menopause and determined the effects of DZ, GE or 17beta-estradiol (E(2)) exposures on chemically induced mutagenesis and carcinogenesis in the mammary glands of female Big Blue transgenic rats. The rats were fed control diet containing the isoflavones and E(2) and treated with a single oral dose of 7,12-dimethylbenz[a]anthracene (DMBA) at PND50. Animals were euthanized at 16 or 20 weeks post-carcinogen treatment to assess mutant frequencies (MFs) and histopathological parameters, respectively. The isoflavones or E(2) supplementation alone resulted in the lac I MFs that were not significantly different from the MFs measured in rats fed the control diet alone. DMBA exposure, however, induced significant increases in the lac I MFs in the mammary tissues of both OVX and INT rats and Hprt MFs in spleen lymphocytes (P < 0.01). In general, feeding the isoflavones or E(2) did not cause any significant changes in DMBA-induced mutagenicity in the mammary tissues. However, feeding the isoflavone mixture (daidzein + genistein; DZG) resulted in a significant reduction in the DMBA-induced lac I MFs (P < 0.05). Cell proliferation as measured by PCNA immunohistochemistry was increased in both OVX and INT rats exposed to DMBA as compared with rats fed control diet (P < 0.05). Mammary histology indicated that hyperplasia was induced in most of the treatment groups including control. Although DMBA did not induce mammary tumors in the OVX rats, adenoma and adenocarcinoma were detected in the mammary glands of INT rats.
Tumor-protective and tumor-promoting actions of dietary whey proteins in an N-methyl-N-nitrosourea model of rat mammary carcinogenesis.(2006)The mammary tumor-protective effects of dietary factors are considered to be mediated by multiple signaling pathways, consistent with the heterogeneous nature of the disease and the distinct genetic profiles of tumors arising from diverse mammary cell populations. In a 7,12-dimethylbenz(a)anthracene-induced model of carcinogenesis, we showed previously that female Sprague-Dawley rats exposed to AIN-93G diet containing whey protein hydrolysate (WPH) beginning at gestation Day 4 had reduced tumor incidence than those exposed to diet containing casein (CAS), due partly to increased mammary differentiation and reduced activity of phase I metabolic enzymes. Here, we evaluated the tumor-protective effects of these same dietary proteins to the direct-acting carcinogen N-methyl-N-nitrosourea (NMU). We found that lifetime exposure to WPH, relative to CAS, decreased mammary tumor incidence and prolonged the appearance of tumors in NMU-treated female rats, with no corresponding effects on tumor multiplicity. At 115 days post-NMU, histologically normal mammary glands from WPH-fed tumor-bearing rats had increased gene expression for the tumor suppressor BRCA1 and the differentiation marker kappa-casein than those of CAS-fed tumor-bearing rats. Tumor-bearing rats from the WPH group had more advanced tumors, with a greater incidence of invasive ductal carcinoma than ductal carcinoma in situ and higher serum C-peptide levels than corresponding rats fed CAS. WPH-fed tumor-bearing rats were also heavier after NMU administration than CAS tumor-bearing rats, although no correlation was noted between body weight and C-peptide levels for either diet group. Results demonstrate the context-dependent tumor-protective and tumor-promoting effects of WPH; provide support for distinct signaling pathways underlying dietary effects on development of mammary carcinoma; and raise provocative questions on the role of diet in altering the prognosis of existing breast tumors.