Therapeutic effect of propolis and paclitaxel on hepatic phase I and II enzymes and marker enzymes in dimethylbenz(a)anthracene-induced breast cancer in female rats

Propolis, a natural beehive product has been known for centuries for a variety of beneficial traditional medicinal properties. The present study was conducted to ascertain the antineoplastic potential of propolis along with paclitaxel against experimental mammary carcinogenesis. Female Sprague Dawley rats at 55 days of age were treated with dimethylbenz(a)anthracene to induce breast cancer. Paclitaxel at a dose of 33 mg/kg body mass intraperitoneally and propolis 50 mg/kg body weight orally was administered to the experimental animals, immediately after the carcinogen treatment and continued until the termination of the study. At the end of the treatment activities of phase I and II xenobiotic metabolizing enzymes and liver marker enzymes were measured. A significant increase in carcinogen activating enzymes, cytochrome P(450), cytochrome b(5) and NADPH cytochrome C reductase with concomitant decrease in phase II enzymes, glutathione transferase and UDP-glucuronyl transferase were observed in animals with mammary cancer. Furthermore there was a significant decrease in alanine aminotransferase, aspartate aminotransferase with a sharp increase in alkaline phosphatase, acid phosphatase and 5' nucleotidase. Propolis treatment caused the activity of these enzymes return to almost normal control levels, indicating the protective effect of propolis against dimethyl benz(a) anthracene induced carcinogenesis. On the basis of the observed results propolis can be considered a promising chemotherapeutic agent and can be administered as an adjuvant with paclitaxel chemotherapy.     

Protective effect of Operculina turpethum against 7,12-dimethyl benz(a)anthracene induced oxidative stress with reference to breast cancer in experimental rats

Reactive oxygen species (ROS) directly or indirectly involves in multistage process of carcinogenesis. Antioxidant activity of methanolic extract of Operculina turpethum stems (MEOT) on 7,12 dimethylbenz(a)anthracene (DMBA) induced breast cancer was investigated in female Sprague-Dawley rats. Changes in the levels of lipid peroxidation and antioxidants system was evaluated in addition to tumour development. Twenty four female rats were divided into four groups: control, DMBA, DMBA + MEOT and MEOT. In the DMBA group, rats were intragastrically administered with 20 mg of DMBA using corn oil as vehicle. Animals of DMBA + MEOT group received a single dose of 20 mg of DMBA dissolved in corn oil intragastrically followed by O. turpethum extract (100 mg/kg body weight), while MEOT group received O. turpethum extract (100 mg/kg body weight) intragastrically daily for a period of 45 days. After the experimental period of 45 days, oxidative stress parameters were assessed in serum, liver and breast of both control and experimental groups. In addition to this, tumour weight of breast was also assessed. A significant increase in lipid peroxidation levels were observed in the tested samples of cancer induced rats while the activities of enzymic antioxidants such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and non-enzymic antioxidants like glutathione (GSH), ascorbic acid (Vitamin C) and α-tocopherol (Vitamin E) were decreased in cancer-bearing animals when compared to control animals. A significant (P < 0.05) increase in the tumour weight was observed in the breast of DMBA group and the breast tumour weight decreased significantly (P < 0.05) in the DMBA + MEOT groups. Oral administration of MEOT remarkably reduced the lipid peroxidation activity and increased the antioxidants level in drug treated animals and decreased the tumour weight significantly (P < 0.05). This result suggests that MEOT shows antioxidant activity and play a protective role against DMBA induced breast cancer.     

Augmented efficacy of tamoxifen in rat breast tumorigenesis when gavaged along with riboflavin, niacin, and CoQ10: effects on lipid peroxidation and antioxidants in mitochondria

Reactive oxygen species (ROS) play a major role in causing mitochondrial changes linked to cancer and metastasis. Uptake of antioxidants by tissue to reduce the ROS production could be instrumental in controlling cancer. Tamoxifen (TAM), a nonsteroidal anti-estrogen drug most used in the chemotherapy and chemoprevention of breast cancer. Riboflavin, niacin and coenzyme Q10 (CoQ10) are proved to be potent antioxidants and protective agents against many diseases including cancer. The objective of this research is to determine the therapeutic efficacy of combinatorial therapy on mammary carcinoma bearing rats in terms of the mitochondrial lipid peroxidation and antioxidant status especially MnSOD. Female albino rats of Sprague-Dawley strain were selected for the investigation. Mammary carcinoma was induced with 7,12-dimethyl benz(a)anthracene (DMBA: 25 mg), and the treatment was started by the oral administration of TAM (10 mg/kg body weight/day) along with riboflavin (45 mg/kg body weight/day), niacin (100 mg/kg body weight/day) and CoQ10 (40 mg/kg body weight/day) for 28 days. The levels of lipid peroxides, activities of enzymic and non-enzymic antioxidants were measured in the mitochondria isolated from the mammary gland and liver of control and experimental rats. Rats treated with DMBA showed an increase in mitochondrial lipid peroxidation (mammary gland 52.3%; liver 25.1%) accompanied by high malondialdehyde levels along with lowered activities of mitochondrial enzymic antioxidants [superoxide dismutase (mammary gland 19.9%; liver 24.8%), catalase (mammary gland 50%; liver 19.7%), glutathione peroxidase (mammary gland 47.8%; liver 31.1%)] and non-enzymic antioxidants [reduced glutathione (mammary gland 14.3%; liver 13.3%), Vitamin C (mammary gland 6.49%; liver 21.4%) and E (mammary gland 20.3%; liver 22.2%)]. Administration of combinatorial therapy restored lipid peroxide level and the activities of enzymic and non-enzymic antioxidants to near normalcy. In addition, antitumour activity was also found to be enhanced which is evident from the increased expression of tumour suppressor gene MnSOD thereby preventing cancer cell proliferation. These results suggested that TAM treatment is the most effective during co-administration of riboflavin, niacin and CoQ10 in terms of mitochondrial antioxidant and antitumour activity.     

Restorative Effect of Kalpaamruthaa, an Indigenous Preparation, on Oxidative Damage in Mammary Gland Mitochondrial Fraction in Experimental Mammary Carcinoma

Cancer prevention and treatment using phytochemicals have attracted increased interest. Recent studies have shown that Semecarpus anacardium Linn nut milk extract (SA), a promising antioxidant and anticancer drug, exerts its anticancer effect through reducing or quenching reactive oxygen species under different conditions. The present study examined whether Phyllanthus emblica Linn fruit, rich in vitamin C content synergistically in combination can enhance both the antioxidant and anticancer activity of S. anacardium nut milk extract in 7, 12-dimethyl benz[a]anthracene (DMBA)-induced experimental mammary carcinoma in rat model. Female Sprague Dawley rats of 180 ± 10g were categorized into six groups. Three groups were administered DMBA (25mg/rat, orally) dissolved in olive oil to induce mammary carcinoma. One of these groups received Kalpaamruthaa (KA) (300mg/kg b.wt, orally) and other group received SA (200mg/kg b.wt, orally) for 14 days after 90 days of DMBA induction. A vehicle treated control and drug control groups were also included. The mitochondrial fraction of untreated DMBA-induced mammary gland showed 2.61-fold increase in lipid peroxidation level and abnormal changes in the activities/levels of mitochondrial enzymic (superoxide dismutase, glutathione peroxidase and glutathione reductase) and non-enzymic (glutathione, vitamin C and vitamin E) antioxidants were observed. DMBA treated rats also showed decline in the activities of mitochondrial enzymes such as succinate dehydrogenase, malate dehydrogenase, α-ketoglutarate dehydrogenase and isocitrate dehydrogenase. In contrast, rats treated with Kalpaamruthaa showed normal lipid peroxide level and antioxidant defenses. The results of the present study highlight the improved antioxidant property of KA than sole treatment of S. anacardium nut milk extract.     

Prepubertal octylphenol exposure up-regulate BRCA1 expression,down-regulate ERα expression and reduce rat mammary tumorigenesis

Background: Endogenous estrogens play an important role in the development of breast cancer. Octylphenol (OP) and genistein (GEN) are estrogen-like chemicals. Prepubertal estradiol and genistein exposure can up-regulate BRCA1 mRNA in mammary gland and reduce futuer breast cancer risk. In the present study, the effects of prepubertal exposure to high-dose OP and GEN on mammary carcinogenesis and the association with the expression of BRCA1 and ERα were investigated. Methods: Prepubertal female Sprague–Dawley rats were exposed to 20, 40, 80 mg/kg OP daily from postnatal day (PND) 22–28, subsequently, the rats were given a single dose of 100 mg/kg 7,12-dimethylbenz [a] anthracene (DMBA) on PND42 to induce mammary tumor. Results: The incidence of DMBA-induced mammary tumors significantly decreased when rats were treated with 40 mg/kg OP. BRCA1 mRNA and protein expression were found up-regulated and ERα expression was down-regulated in the mammary tumor when rats were exposed to 40 mg/kg octylphenol. Conclusion: Exposure 40 mg/kg octylphenol can reduce later breast cancer risk in prepubertal Sprague–Dawley rats, the protective effect of OP is associated with persistent up-regulation of BRCA1 and down-regulation of ERα in the mammary tumor.     

Zingerone induced caspase‐dependent apoptosis in MCF‐7 cells and prevents 7,12‐dimethylbenz(a)anthracene‐induced mammary carcinogenesis in experimental rats

Breast cancer is a prevalent of tumoregenesis in women and reports for the maximum mortality and morbidity in the global. Ginger (Zingiber officinale) is the mainly widespread spice and herbal remedies used in the world. Since antique periods, ginger has been used in Greece, India and China for the curing of upset stomach, nausea, diarrhea, colds, and headaches. The current work was planned to explore the anticancer properties of zingerone (ZO) toward 7,12‐dimethylbenz(a)anthracene (DMBA)‐treated mammary carcinogenesis in Sprague‐Dawley (SD) rats and MCF‐7 mammary cancer cells. The mammary carcinogenesis was produced through a single dosage of DMBA (20 mg/kg bwt) mixed in soya oil (1 mL) administrated intragastrically with a gavage. We found improved concentrations of lipid peroxidation (LOOH and TBARS), carcinoembryonic antigen, lowered levels of enzymatic (CAT, GPx, and SOD), and nonenzymatic (vitamin E, GSH, and vitamin C) antioxidant in mammary tissues and plasma of DMBA‐induced cancer bearing animals. Moreover, augmented concentrations of phase I (Cyt‐b₅ and CYP₄₅₀) and reduced levels of phase II (GR and GST) detoxification microsomal proteins in mammary tissues were noticed. ZO administrations significantly reverted back to all these parameters in this way, showing efficient of anticancer effect. Furthermore, our in vitro study also supported the anticancer effect of the treatment of ZO were noticed loss of cell viability, improved reactive oxygen species formation, and reduced MMP. Furthermore, the status of apoptosis proteins such as Bcl‐2, Bax, and Bid expressions was determined by using Western blot analysis techniques. Overall, these results proposed the anticancer effect of ZO toward DMBA‐induced mammary cancer in SD animals and Michigan cancer foundation‐7 mammary cancer cells.     

The effect of zinc and phytoestrogen supplementation on the changes in mineral content of the femur of rats with chemically induced mammary carcinogenesis

The aim of this study was to assess skeletal effects of zinc or zinc with phytoestrogen (resveratrol or genistein) supplementation in an animal model of rats with DMBA-induced mammary carcinogenesis. The changes in bone parameters such as the length and mass were examined, as well as the changes in concentrations of selected minerals: calcium, magnesium, zinc, iron and phosphorus. Moreover, the investigations focused on finding the differences between the levels of iron and zinc in other tissues: the liver, spleen and serum of the examined rats.Fifty-six female Sprague–Dawley rats, 40 days old, were divided into four groups, regardless of the diets: standard (77 mg Zn kg/food), zinc (4.6 mg/mL via gavage), zinc (4.6 mg/mL) plus resveratrol (0.2 mg/kg bw), and zinc (4.6 mg/mL) plus genistein (0.2 mg/kg bw) for a period from 40 days until 20 weeks of age. The study rats were also treated with 7,12-dimethyl-1,2-benz[a]anthracene (DMBA) to induce mammary carcinogenesis.The applied diet and the advanced mammary cancer did not affect macrometric parameters of the rats’ bones, but they strongly affected their mineral content. It was found that mammary cancer, irrespectively of the applied diet, significantly modified the iron level in the femur, liver, spleen and serum of the examined rats. In addition, zinc supplementation significantly lowered the levels of calcium, magnesium and phosphorus in the femur of rats with mammary cancer as compared with respective levels in the control group. So, it was found that additional supplementation with zinc, which is generally considered to be an antioxidant, with the co-existing mammary carcinoma, increased the unfavorable changes as concerns the stability of bone tissue. The appropriate combination of zinc and phytoestrogens (resveratrol or genistein) could help prevent or slow bone loss associated with a range of skeletal disorders in breast cancer.     

Charles River Sprague Dawley rats lack early age-dependent susceptibility to DMBA-induced mammary carcinogenesis

Developmental stages of mammary glands influence their susceptibility to initiating events related to carcinogenesis. The "window of susceptibility" to mammary carcinogenesis is classically defined as the time in early puberty when the mammary gland morphology is most sensitive to initiation events. Administration of the polyaromatic hydrocarbon, 7,12-dimethylbenz(a)anthracene (DMBA), in a single oral dose yields maximal mammary tumor formation when administered in this "window". We examined the DMBA treated mammary glands, precursor lesions, and morphology of the uninvolved mammary epithelium for the first 100 days of life for Charles River Sprague Dawley CD(R) IGS. Our goal was to determine the DMBA dose at which 50% of the rats (IC50) developed carcinoma in situ (CIS) within three months of dosing. Here we demonstrate, rather than the classical U-shaped dose curve in which there is maximum sensitivity for DMBA at 50 days, there is an increasing degree of sensitivity with age in the CD(R) IGS rat. Additionally, we report that vehicle-treated animals developed mammary CIS without any known initiator, and 100 day virgin animals demonstrated lactational changes, independent of DMBA exposure or dose. Lastly, we demonstrate this strain of virgin female rats has elevated pituitary prolactin immunoreactivity independent of the level of mammary differentiation. We conclude this strain of Charles River Sprague Dawley rats has prolactin-induced pituitary stimulation, and therefore, the window of susceptibility for mammary tumorigenesis is absent.     

VEGF-A regulates sFlt-1 production in trophoblasts through both Flt-1 and KDR receptors

In the present study, we investigated the effect of allyl isothiocyanate (AITC) on liver detoxification signaling pathway in 7,12-dimethylbenz(a)anthracene (DMBA)-induced mammary carcinogenesis. Mammary tumor was induced by a single dose of DMBA (25 mg/rat) injected subcutaneously near the mammary gland in Sprague–Dawley rats. DMBA-alone-treated rats show an increased synthesis of phase I detoxification enzymes, lipid peroxidative markers, liver marker enzymes, and lipid profiles whereas, depletion of phase II detoxification enzymes and antioxidants in rat liver tissues. Oral administration of AITC restored the levels of biochemical markers in DMBA-treated rats. Furthermore, histopathological results also confirmed that AITC protects DMBA-mediated hepatocellular damage. We also observed that AITC treatment significantly downregulates AhR and upregulates the expression of Nrf2 in DMBA-treated rats. The binding efficacy of AITC with AhR and Nrf2 analysis by molecular docking studies reveals that AITC has strong interaction with AhR and Nrf2 proteins through hydrogen and hydrophobic interactions. Thus, AITC prevents DMBA-induced mammary carcinogenesis via inhibition of phase I and induction of phase II detoxification enzymes by modulating AhR/Nrf2 signaling pathway.     

Chemoprevention of mammary tumorigenesis and chemomodulation of the antioxidative enzymes and peroxidative damage in prepubertal Sprague Dawley rats by Biochanin A

Although chemopreventive action of Biochanin A against various cancers including that of prostate, breast, colon, and fore-stomach has been reported earlier, none of the studies was made in prepubertal subjects. The present study appears to be the first one on prepubertal rats that indicates the efficacy of the test compound in the prevention of tumorigenesis. The antioxidative status and xenobiotic metabolism were also evaluated to understand the mechanism of Biochanin A induced prevention of cancer. For the tumorigenesis study 500 μg/g bwt of Biochanin A or vehicle dimethyl sulfoxide (DMSO) s.c, was injected at 16th, 18th, and 20th days post-partum followed by the administration of dimethylbenz[a]nthracene (DMBA) (80 μg/g bwt) at 50th day. In another set of experiments, to study the involvement of peroxidative process in the mechanism of action of test compound, different antioxidant parameters were studied following the administration of two different doses of Biochanin A (0.5 and 50 mg/kg bwt, through oral gavage for 10 days) in the prepubertal rats from day 16 post-partum. Results showed a significant reduction in the mammary tumors (more than 40%) in Biochanin A treated animals, as compared to animals treated with DMBA only. Spectrophotometric enzyme estimations revealed that the specific activities of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione transferase (GST), DT-diaphorase (DTD), and reduced glutathione (GSH) levels were increased, whereas specific activities of lactate dehydrogenase (LDH) and lipid peroxidation (LPO) were decreased significantly, both in liver as well as in mammary gland, in animals treated with Biochanin A prepubertally. These results reveal the possible involvement of the antioxidative and metabolic enzymes in the suppression of cancer burden and incidence in a prepubertal rat model suggesting that the intake of this phytoestrogen at an early stage may help in lowering the risk of mammary tumor.     

Prevention of chemically induced mammary tumorigenesis by daidzein in pre-pubertal rats: the role of peroxidative damage and antioxidative enzymes

Isoflavones are biologically active plant derived compounds that have several health promoting effects. In the present study hitherto unknown effects of one of the well known isoflavonoids, daidzein, has been evaluated on its chemo-preventive action against breast cancers in pre-pubertal rats. Either daidzein (500 μg/g bwt) or vehicle, dimethyl sulphoxide (DMSO), was administered at 16th, 18th, and 20th day post-partum and the chemopreventive efficacy was evaluated in dimethylbenz[a]nthracene (DMBA) induced Sprague-Dawley rats, at 50th day. To elucidate the mechanism of action, the antioxidative status was also examined in the liver and mammary gland of prebubertal rats using two different doses of daidzein (0.5 mg/kg bwt and 50 mg/kg bwt, p.o.) for 10 days. The specific activity of antioxidant enzymes as well as reduced glutathione (GSH) level and peroxidative damage were evaluated spectrophotometrically, both in liver as well as in mammary gland. Animals treated with daidzein pre-pubertally, showed a significant reduction in the tumorigenesis of mammary gland up to 37.4% as compared to animals induced for tumors with DMBA. In animals treated with 50 mg/kg of daidzein, a significant increase in the specific activities of the antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione transferase (GST), DT-diaphorase (DTD), and in GSH content were observed in both liver and mammary gland. Expectedly, the specific activity of lactate dehydrogenase (LDH) and level of peroxidative damage was decreased, as compared to that of control group of animals. Our results suggest that, daidzein can be considered as a potent chemopreventive agent against mammary carcinogenesis in pre-pubertal animals, with modulation of antioxidant enzymes being one of its mechanisms of actions.     

Alteration of DMBA-induced oxidative stress by additive action of a modified indigenous preparation--Kalpaamruthaa

The present study investigated the protective efficacy of the novel preparation named as Kalpaamruthaa (KA, includes Semecarpus anacardium Linn nut milk extract (SA), dried powder of Phyllanthus emblica fruit and honey) on the peroxidative damage and abnormal antioxidant levels in the hepatic mitochondrial fraction of 7,12-dimethylbenz(a)anthracene (DMBA)-induced mammary carcinoma rats. Female Sprague-Dawley rats of weight 180+/-10 g were categorized into six groups. Three groups were administered DMBA (25 mg/rat dissolved in olive oil, orally) to induce mammary carcinoma. One of these groups received KA treatment (300 mg/kg b.wt., orally) and other group received SA (200 mg/kg b.wt., orally) for 14 days after 90 days of DMBA induction. Vehicle-treated control and drug control groups were also included. The hepatic mitochondrial fraction of untreated DMBA rats showed 2.96-fold increase in MDA content when compared to control rats and abnormal changes in the activities/levels of mitochondrial enzymic (superoxide dismutase, glutathione peroxidase and glutathione reductase) and non-enzymic (glutathione, vitamin C and vitamin E) antioxidants were observed. DMBA-treated rats also showed decline in the activities of mitochondrial enzymes such as succinate dehydrogenase, alpha-ketoglutarate dehydrogenase, malate dehydrogenase and isocitrate dehydrogenase. In contrast, rats treated with SA and KA showed normal lipid peroxidation antioxidant defenses and mitochondrial enzymes, thereby showing the protection rendered by SA and KA. Although, KA treatment exhibited more profound effect in inhibiting DMBA-induced oxidative stress than sole SA treatment. Results of the study indicate that the anticarcinogenic activity of KA during DMBA-initiated mammary carcinogenesis is mediated through alteration of hepatic antioxidant status as well as modulation of TCA cycle enzymes. On the basis of the observed results, KA can be considered as a readily accessible, promising and novel cancer chemopreventive agent.     

Influence of treatment of diabetic rats with combinations of pycnogenol, β‐carotene,and α‐lipoic acid on parameters of oxidative stress

Treatment with antioxidants may act more effectively to alter markers of free radical damage in combinations than singly. This study has determined whether treatment with combinations of pycnogenol, β‐carotene, and α‐lipoic acid was more effective at reducing oxidative stress in diabetic rats than treatment with these antioxidants alone. It is not feasible, based on this study, to assume that there are interactive effects that make combinations of these antioxidants more effective than any one alone to combat oxidative stress. Female Sprague‐Dawley rats, normal and streptozotocin‐induced diabetic, were treated (10 mg/kg/day ip for 14 days) with pycnogenol, β‐carotene, pycnogenol + β‐carotene, or pycnogenol + β‐carotene + α‐lipoic acid; controls were untreated. Concentrations of thiobarbituric acid reactive substances, glutathione and glutathione disulfide, and activities of glutathione reductase, glutathione peroxidase, superoxide dismutase, and catalase were measured in liver, kidney, and heart. Four types of effects were observed: (1) treatment with β‐carotene alone either reversed (cardiac glutathione disulfide) or elevated (cardiac glutathione, hepatic glutathione peroxidase activity) levels seen in diabetic animals; (2) β‐carotene alone produced no effect, but pycnogenol both alone and in combinations elevated (renal glutathione peroxidase and glutathione reductase activities, hepatic glutathione reductase activity and glutathione disulfide) or depressed (cardiac glutathione disulfide) levels seen in untreated diabetic animals; (3) all treatments with antioxidants, either alone or in combination, either normalized (lipid peroxidation in all tissues), elevated (hepatic GSH, cardiac glutathione peroxidase activity), or had no effect on (activities of hepatic catalase and superoxide dismutase in all tissues) levels seen in diabetic animals; (4) in only one case (cardiac glutathione reductase activity) levels in diabetic animals treated with combinations of antioxidants were normal, but elevated in animals treated with either antioxidant alone. Antioxidant effects seem to be dependent on the nature of the antioxidant used and not on combination effects. © 2005 Wiley Periodicals, Inc. J Biochem Mol Toxicol 18:345–352, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jbt.20046     

Dietary fish oil associated with increased apoptosis and modulated expression of Bax and Bcl-2 during 7,12-dimethylbenz(alpha)anthracene-induced mammary carcinogenesis in rats

The present study investigated the chemopreventive effect of dietary fish oil (Maxepa), rich in eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on induction of apoptosis in mammary carcinogenesis model. Mammary carcinogenesis was initiated by a single, tail vein injection of 7,12-dimethylbenz(alpha)anthracene (DMBA) (0.5mg/0.2ml corn oil/100g body weight) at 7 weeks of animal age. Ninety female Sprague-Dawley rats were divided into two parts: part one was used for histology and immunohistochemical study and part two for morphological analysis. Each part consists of three experimental groups having 15 animals, i.e., Group A (DMBA control), Group B (DMBA+fish oil) and Group C (DMBA+corn oil). Rats were fed either fish oil or corn oil (0.5ml/day/rat) by oral gavage, 2 weeks prior to DMBA injection. Treatment was continued 25 weeks, studying histopathology, expression of Bax and Bcl-2 proteins by immunohistochemistry and apoptosis by TUNEL assay and morphological study at 36 weeks. Results showed that the fish oil-treated group exhibited a substantial increase in Bax (p<0.05) immunolabelling and a reduction of Bcl-2 immunopositivity (p<0.05), and increased TUNEL-positive apoptotic cells (p<0.05); however, corn oil treatment did not show these beneficial effects toward mammary preneoplasia. We conclude that fish oil has the potential to play a significant role in limiting mammary tumourigenesis in vivo.     

Early-in-life dietary zinc deficiency and supplementation and mammary tumor development in adulthood female rats

Zinc deficiency during pregnancy and postnatal life can adversely increase risk of developing human diseases at adulthood. The present study was designed to evaluate whether dietary zinc deficiency or supplementation during the pregnancy, lactation and juvenile stages interferes in the development of mammary tumors induced by 7,12-dimethylbenzanthracene (DMBA) in female Sprague–Dawley (SD) rats. Pregnant female SD rats were allocated into three groups: zinc-adequate diet (ZnA - 35-mg/kg chow), zinc-deficient diet (ZnD - 3-mg/kg chow) or zinc-supplemented diet (ZnS - 180-mg/kg chow) during gestational day 10 (GD 10) until the litters' weaning. Female offspring received the same diets as their dams until postnatal day (PND) 51. At PND 51, the animals received a single dose of DMBA (50 mg/kg, ig) and zinc-adequate diets. At PND 180, female were euthanized, and tumor samples were processed for histological evaluation and gene expression microarray analysis. The ZnD induced a significant reduction in female offspring body weight evolution and in mammary gland development. At late in life, the ZnD or ZnS did not alter the latency, incidence, multiplicity, volume or histological types of mammary tumors in relation to the ZnA group. However, the total tumor number in ZnS group was higher than in ZnA group, accompanied by distinct expression of 4 genes up- and 15 genes down-regulated. The present findings indicate that early-in-life dietary zinc supplementation, differently to zinc deficiency, has a potential to modify the susceptibility to the development of mammary tumors induced by DMBA.     

DMBA诱导树鼩乳腺肿瘤(中缅树鼩)

目的:建立一个合适的乳腺癌动物模型将在研究人类乳腺癌的发生、发展、转移等方面中发挥着越来越重要的作用。7,12-二甲基苯并蒽(7,12-dimethylbenz anthracene,DMBA)在实验中能诱导大鼠产生乳腺肿瘤。树鼩的基因的结构与人类的相似程度比啮齿类动物要高,而且树鼩的自发性乳腺癌已经有被报道,因而树鼩很有可能是研究乳腺肿瘤更合适的动物模型。因此我们想用致癌剂DMBA诱导树鼩产生乳腺肿瘤而建立树鼩的乳腺肿瘤模型。方法:在这个研究中,我们采用了十只在分娩之后失去幼崽的雌树鼩,其中一半的树鼩在腰部双侧乳房的脂肪垫注射100 mg/kg的DMBA,其余的树鼩作为对照组没有作DMBA处理。对生成的肿瘤组织进行病理切片HE染色的形态特点分析以及免疫组化化学法测定Ki-67、雌激素受体、孕酮受体、人表皮生长因子受体-2、E-钙粘蛋白、P120连环蛋白的表达。结果:通过诊断在DMBA处理的树鼩中,5分之1发展浸润性导管癌,其余发展成原位导管癌。结果还证明了诱导出来的乳腺肿瘤的形态学和病理学特征与人类的浸润性导管癌相似。结论:结果显示我们采用DMBA注射失去幼崽的雌树鼩的乳腺来诱导乳腺肿瘤是有效的,诱导出来的肿瘤组织学特征与人的乳腺癌相似,诱导的肿瘤组织表达目前人常用的乳腺癌相关分子生物学标记,并且表达情况与人的乳腺癌相似。这表明了DMBA诱导树鼩乳腺癌可以提供一个适合于研究人类乳腺癌发生、发展、转移和治疗的动物模型。     

Cytoprotective and antioxidant role of diallyl tetrasulfide on cadmium induced renal injury: an in vivo and in vitro study

Cadmium (Cd) is an environmental and industrial pollutant that affects various organs in humans and animals. A body of evidence has accumulated implicating the free radical generation with subsequent oxidative stress in the biochemical and molecular mechanisms of Cd toxicity. Since kidney is the critical target of Cd toxicity, we carried out this study to investigate the effects of diallyl tetrasulfide (DTS), an organosulfur compound derived from garlic on Cd induced toxicity in the kidney of rats and also in the kidney cell line (vero cells). In experimental rats, subcutaneous administration of Cd (3 mg/kg bw/day) for 3 weeks induced renal damage, which was evident from significantly increased levels of serum urea and creatinine with significant decrease in creatinine clearance. A markedly increased levels of lipid peroxidation markers (thiobarbituric acid reactive substances and lipid hydroperoxides) and protein carbonyl contents with significant decrease in nonenzymic antioxidants (total sulphydryl groups, reduced glutathione, vitamin C and vitamin E) and enzymic antioxidants (superoxide dismutase, catalase, glutathione peroxidase and glutathione-S-transferase) as well as glutathione metabolizing enzymes (glutathione reductase, and glucose-6-phosphate dehydrogenase) were also observed in Cd intoxicated rats. Coadministration of DTS (40 mg/kg bw/day) and Cd resulted in the reversal of the kidney function accompanied by a significant decrease in lipid peroxidation and increase in the antioxidant defense system. In vitro studies with vero cells showed that incubation of DTS (5-50 microg/ml) with Cd (10 microM) significantly reduced the cell death induced by Cd. DTS at 40 microg/ml effectively blocked the cell death and lipid peroxidation induced by Cd (10 microM) indicating its cytoprotective property. Further, the flow cytometric assessment on the level of intracellular reactive oxygen species using a fluorescent probe 2', 7'-dichlorofluorescein diacetate (DCF-DA) confirmed the Cd induced intracellular oxidative stress in vero cells, which was significantly suppressed by DTS (40 microg/ml). The histopathological studies in the kidney of rats also showed that DTS (40 mg/kg bw/day) markedly reduced the toxicity of Cd and preserved the architecture of renal tissue. The present study suggests that the cytoprotective potential of DTS in Cd toxicity might be due to its antioxidant and metal chelating properties, which could be useful for achieving optimum effects in Cd induced renal damage.     

Copper and Resveratrol Attenuates Serum Catalase, Glutathione Peroxidase, and Element Values in Rats with DMBA-Induced Mammary Carcinogenesis

In this paper, a hypothesis was assessed whether or not the intoxication with copper and supplementation with copper plus resveratrol would result in changes in the activities of catalase and glutathione peroxidase and moreover if the characteristic changes would appear in concentrations of copper, iron, calcium, magnesium, and zinc in the serum of rats with chemically induced carcinogenesis. Female Sprague-Dawley rats were divided into study groups which, apart from the standard diet, were treated with copper (42.6 mg Cu/kg food as CuSO₄·5H₂O) or copper plus resveratrol (0.2 mg/kg body) via gavage for a period from 40 days until 20 weeks of age. In cancer groups, the rats were treated with a dose of 80 mg/body weight of 7,12-dimethyl-1,2-benz[a]anthracene (DMBA) given in rapeseed oil at 50 and 80 days of age to induce mammary carcinogenesis. The control groups included the rats kept in the same conditions and fed with the same diet as the animals from the study groups, but not DMBA-treated. The activity of catalase significantly decreased in groups of rats with mammary carcinogenesis that were supplemented with copper (p?<?0.05) or copper plus resveratrol (p?<?0.001) in comparison with the control groups that received the same diets. In cancer groups of nonsupplemented rats, the increase of glutathione peroxidase activity was observed. The process of carcinogenesis and the applied supplementation significantly altered the concentrations of trace elements in serum, in particular as concerns iron and copper. The mean serum iron levels in rats with breast cancer were significantly lower than those in the control groups (p?<?0.001). The mean serum copper levels significantly decreased in the groups of rats with mammary carcinogenesis that were supplemented with copper or copper plus resveratrol in comparison with the control groups that received the same diets (p?<?0.001). The characteristic changes in iron content and the zinc/copper and zinc/iron ratios in blood may be used as one of the prognostic factors in breast cancer research.     

Comparison of Protective Effect of Aqueous and Ethanolic Extracts of Propolis against Gastric Ulceration in Rats

This study focused on the protective effects of different types of propolis extracts on gastric mucosa in indomethacin-induced rats. The animals were divided into nine groups: control, negative control (ulcer), positive control (omeprazole), and experimental groups, which were summarized by 200, 400, and 600 mg/kg, bw for aqueous-based and ethanol, respectively. According to the histopathological evaluation, more than others, the doses of 200 and 400 mg/kg of aqueous-based propolis extracts had different degrees of positive effects on the gastric mucosa. Generally, the biochemical analyses of the gastric tissue showed a correlation with microscopic evaluations. According to the phenolic profile analysis, while pinocembrin (684.34±1.70 μg/ml) and chrysin (540.54±9.06 μg/ml) were the most abundant phenolics in the ethanolic extract, ferulic acid (53.77±0.07 μg/ml) and p-coumaric acid (52.61±0.42 μg/ml) dominated the aqueous-based extract. Also, the total phenolic content (TPC), total flavonoid content (TFC), and DPPH radical scavenging activity of the ethanolic extract showed almost nine-fold superiority compared to the aqueous-based extracts. Based on data from preclinical data, it was decided that the best doses for the main goal of the study were 200 mg and 400 mg/kg, bw for aqueous-based propolis extract.     

7,8-Dihydroxycoumarin exerts antitumor potential on DMBA-induced mammary carcinogenesis by inhibiting ERα, PR,EGFR, and IGF1R: involvement of MAPK1/2-JNK1/2-Akt pathway

Breast cancer (BC) is a persistent and impulsive metabolic disorder with the highest prevalence in women, worldwide. 7,12-Dimethylbenz(a)anthracene (DMBA) is a potent polyaromatic hydrocarbon (PAH)-based carcinogen producing mammary carcinomas in rats resembling the human hormone-dependent BC. 7,8-Dihydroxycoumarin (78DC) is a coumarin derivative that possesses diversified and favorable pharmacology profile to be considered in anticancer research against various malignancies. The present study was intended to investigate the antiproliferative and chemotherapeutic potentials of 78DC (20, 40, and 80 mg/kg BW) against DMBA (20 mg in olive oil)-induced mammary carcinoma Sprague-Dawley rats. We established the in silico approach for evaluation of the effect of 78DC on hormonal (estrogen receptor-α (ERα), progesterone receptor (PR)), growth factor receptors (EGFR and IGFR), 17β-hydroxysteroid dehydrogenase type 1 (17β-HD1), and aromatase. Effect of 78DC on estrogen synthesis, tumor growth, proliferation markers (Ki-67 and PCNA), cytokines (IL-10, IL-1β, IL-12), chemokine (MCP-1), and cellular expressions of ERα, PR, EGFR, IGF1R, p-MAPK1/2, p-JNK1/2, p-Akt, 17β-HD1, and aromatase was evaluated in mammary carcinoma bearing SD rats. DMBA induces large tumor burden and histological alterations in mammary gland with a subsequent increase in ERα, PR, EGFR, IGF1R, Ki-67, proliferating cell nuclear antigen (PCNA ), cytokines, and chemokine expressions. This was also correlated with the changes in rapid cell differentiation and proliferation. In contrast, 78DC treatment to the cancer-bearing animals abbreviated these changes and revealed to possess antitumorigenic and antiproliferative potentials. Further, a significant decrease in expressions of ERα, PR, EGFR, IGFR, p-MAPK1/2, p-JNK1/2, p-Akt, 17β-HD1, and aromatase signifies a reduction in estrogen sensitivity and secondary signaling pathways that may contribute to the prevention of tumor growth. The current findings revealed that 78DC potentially reduce cancer cell proliferation and reverted mammary cancer-induced changes in experimental animals in a dose-dependent manner.