Phytonutrients Differentially Stimulate NAD(P)H:Quinone Oxidoreductase, Inhibit Proliferation, and Trigger Mitotic Catastrophe in Hepa1c1c7 Cells.

Phytonutrients have rapidly emerged as natural food chemicals possessing multifaceted biological actions that may support beneficial health outcomes. Among the vast array of phytonutrients currently being studied, sulforaphane, curcumin, quercetin, and resveratrol have been frequently reported to stimulate the expression of endogenous detoxification enzymes and may thereby facilitate the neutralization of otherwise harmful environmental agents. Some of these same phytonutrients, however, have also been implicated in disrupting normal cell proliferation and hence may possess toxic properties in and of themselves. In this study, we characterize the respective minimum threshold concentrations of the aforementioned phytonutrients in Hepa1c1c7 cells that stimulate NAD(P)H: quinone oxidoreductase (NQO1), a key enzyme in the hepatic neutralization of menadione, other biological oxidants, and some environmental carcinogens. Moreover, our findings demonstrate that relatively low concentrations of either sulforaphane or curcumin significantly (P < .05) increase NQO1 protein expression and activity without triggering G2/M cell cycle arrest or mitotic catastrophe. The minimal quercetin concentration inducing NQO1, however, was 100-fold higher than that which disrupted mitosis. Also, while resveratrol modestly stimulated NQO1, the minimally effective resveratrol concentration concomitantly induced evidence of cellular apoptosis. Taken together, these findings indicate that only particular phytonutrients are likely efficacious in upregulating NQO1 activity without also leading to hepatic cytotoxicity.

Curcumin binds tubulin, induces mitotic catastrophe, and impedes normal endothelial cell proliferation.

Curcumin, a component of turmeric spice that imparts flavor and color to curry, is thought to possess anti-inflammatory and antioxidant properties in biological tissues. However, while such efficacies have been described in the context of carcinogenesis, the impact of curcumin on normal cell cycle regulation is poorly understood. Here, we provide evidence of curcumin toxicity in proliferating bovine aortic endothelial cells, at concentrations relevant to the diet and below those previously reported in cancer models. Upon confirming curcumin's ability to upregulate hemeoxygenase-1 in a dose-dependent fashion, we found the minimally efficacious curcumin concentration to also inhibit endothelial cell DNA synthesis. Moreover, curcumin concentrations below the minimum 2 µM threshold required to induce hemeoxygenase-1 bound tubulin protein in vitro and triggered hallmark evidence of mitotic catastrophe in vivo. Concentrations as low as 0.1 µM curcumin led to disproportionate DNA segregation, karyorrhexis, and micronucleation in proliferating endothelial cells. While suggesting a mechanism by which physiological curcumin concentrations inhibit cell cycle progression, these findings describe heretofore unappreciated curcumin toxicity with potential implications for endothelial growth, development, and tissue healing.

A high protein moderate carbohydrate diet fed at discrete meals reduces early progression of N-methyl-N-nitrosourea-induced breast tumorigenesis in rats.

Breast cancer is the most prevalent cancer in American women. Dietary factors are thought to have a strong influence on breast cancer incidence. This study utilized a meal-feeding protocol with female Sprague-Dawley rats to evaluate effects of two ratios of carbohydrate:protein on promotion and early progression of breast tissue carcinomas. Mammary tumors were induced by N-methyl-N-nitrosourea (MNU) at 52 d of age. Post-induction, animals were assigned to consume either a low protein high carbohydrate diet (LPHC; 15% and 60% of energy, respectively) or a high protein moderate carbohydrate diet (HPMC; 35% and 40% of energy, respectively) for 10 wk. Animals were fed 3 meals/day to mimic human absorption and metabolism patterns. The rate of palpable tumor incidence was reduced in HPMC relative to LPHC (12.9 +/- 1.4%/wk vs. 18.2 +/- 1.3%/wk). At 3 wk, post-prandial serum insulin was larger in the LPHC relative to HPMC (+136.4 +/- 33.1 pmol/L vs. +38.1 +/- 23.4 pmol/L), while at 10 wk there was a trend for post-prandial IGF-I to be increased in HPMC (P = 0.055). There were no differences in tumor latency, tumor surface area, or cumulative tumor mass between diet groups. The present study provides evidence that reducing the dietary carbohydrate:protein ratio attenuates the development of mammary tumors. These findings are consistent with reduced post-prandial insulin release potentially diminishing the proliferative environment required for breast cancer tumors to progress.

Regulation of estrogen receptor alpha expression in human breast cancer cells by sulforaphane.

Sulforaphane [SUL, 1-isothiocyanato-4-(methylsulfinyl)butane] is an isothiocyanate derived from glucoraphanin present in cruciferous vegetables, and it has a variety of potential chemopreventive actions. We analyzed the effects of SUL on the proliferation of human breast cancer cells and on the expression of estrogen receptor alpha (ERalpha) protein and mRNA in MCF-7 cells. Sulforaphane inhibited cell proliferation with IC(50) values at 24 and 48 h of 12.5 and 7.5 muM doses, respectively, and decreased ERalpha protein expression at concentrations between 2.5 and 30 muM. Inhibition of ERalpha protein expression was also accompanied by decreased progesterone receptor expression. MCF-7 ERalpha mRNA expression was inhibited by SUL at a dose of 30 muM, but not at lower SUL concentrations. At SUL doses <30 muM, the SUL-induced suppression of ERalpha protein was reversed by preincubation with the proteasome inhibitor MG132 and was accompanied by an increase in protein levels of the 20S catalytic core subunit PSMB5. Therefore, SUL can inhibit the expression of ERalpha protein in MCF-7 cells in part by inhibition of ERalpha mRNA transcription as well as by a mechanism that may involve increased proteasome-mediated degradation. These data provide new insights into mechanisms by which SUL inhibits proliferation of and down-regulates hormone receptor expression in MCF-7 cells.

Suppression of microtubule dynamic instability and turnover in MCF7 breast cancer cells by sulforaphane.

Sulforaphane (SFN), a prominent isothiocyanate present in cruciferous vegetables, is believed to be responsible along with other isothiocyanates for the cancer preventive activity of such vegetables. SFN arrests mitosis, possibly by affecting spindle microtubule function. A critical property of microtubules is their rapid and time-sensitive growth and shortening dynamics (dynamic instability), and suppression of dynamics by antimitotic anticancer drugs (e.g. taxanes and the vinca alkaloids) is central to the anticancer mechanisms of such drugs. We found that at concentrations that inhibited proliferation and mitosis of MCF7-green fluorescent protein-alpha-tubulin breast tumor cells by approximately 50% (~15 microM), SFN significantly modified microtubule organization in arrested spindles without modulating the spindle microtubule mass, in a manner similar to that of much more powerful antimitotic drugs. By using quantitative fluorescence video microscopy, we determined that at its mitotic concentration required to inhibit mitosis by 50%, SFN suppressed the dynamic instability of the interphase microtubules in these cells, strongly reducing the rate and extent of growth and shortening and decreasing microtubule turnover, without affecting the polymer mass. SFN suppressed the dynamics of purified microtubules in a similar fashion at concentrations well below those required to depolymerize microtubules, indicating that the suppression of dynamic instability by SFN in cells is due to a direct effect on the microtubules. The results indicate that SFN arrests proliferation and mitosis by stabilizing microtubules in a manner weaker than but similar to more powerful clinically used antimitotic anticancer drugs and strongly support the hypothesis that inhibition of mitosis by microtubule stabilization is important for SFN's chemopreventive activity.

Diet, autophagy, and cancer: a review.

A host of dietary factors can influence various cellular processes and thereby potentially influence overall cancer risk and tumor behavior. In many cases, these factors suppress cancer by stimulating programmed cell death. However, death not only can follow the well-characterized type I apoptotic pathway but also can proceed by nonapoptotic modes such as type II (macroautophagy-related) and type III (necrosis) or combinations thereof. In contrast to apoptosis, the induction of macroautophagy may contribute to either the survival or death of cells in response to a stressor. This review highlights current knowledge and gaps in our understanding of the interactions among bioactive food constituents, autophagy, and cancer. Whereas a variety of food components including vitamin D, selenium, curcumin, resveratrol, and genistein have been shown to stimulate autophagy vacuolization, it is often difficult to determine if this is a protumorigenic or antitumorigenic response. Additional studies are needed to examine dose and duration of exposures and tissue specificity in response to bioactive food components in transgenic and knockout models to resolve the physiologic implications of early changes in the autophagy process.

The combination of genistin and ipriflavone prevents mammary tumorigenesis and modulates lipid profile.

BACKGROUND & AIMS: Recent reports have indicated that soy isoflavones may be protective against breast cancer. However, the effects of the synthetic isoflavone, ipriflavone, on mammary tumorigenisis, alone or in combination with genistin, a soy isoflavone, have not been investigated. METHODS: Eighty-eight 36-day-old female Sprague-Dawley rats were divided as follows: Gen (20 mg genistin/kg body weight), Ipr (200 mg ipriflavone/kg body weight), Gen+Ipr (20/200 mg per kg body weight, respectively), and control (solvent vehicle). A week later, animals were injected with a single dose of methylnitrosourea. The isoflavones and solvent vehicle were administered daily via gastric gavage for 84 days post methylnitrosurea injection. RESULTS: The Gen+Ipr group had the lowest number of palpable tumors and adenocarcinomas per group, the least palpable tumors per rat, and the highest serum total and non-HDL cholesterol levels. No changes in circulating levels of indicators of oxidative stress were detected due to treatment. CONCLUSIONS: The findings of this study imply that the combination of genistin and ipriflavone is effective in suppressing mammary methylnitrosurea-induced tumorigenesis and also the lipid environment of the tumor cells that impact tumor growth or proliferation. Further studies are needed to establish the optimal dose of genistin and ipriflavone, individually or in combination, for the prevention of mammary tumorigenesis.

WITHDRAWN: The combination of genistin and ipriflavone prevents mammary tumorigenesis and modulates lipid profile.

This article has been withdrawn consistent with Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). The Publisher apologizes for any inconvenience this may cause.

Characterization of proteomic and metabolomic responses to dietary factors and supplements.

Over the past decade there has been a renewed interest in research and development of both dietary and nutritional supplements. Significant advancements have been made in the scientific assessment of the quality, safety, and efficacy of these products because of the strong interest in and financial support of these projects. As research in both fields continues to advance, opportunities to use new and innovative research technologies and methodologies, such as proteomics and metabolomics, are critical for the future progress of the science. The purpose of the symposium was to begin the process of communicating new innovative proteomic and metabolomic methodologies that may be applied by researchers in both the nutrition and the natural product communities. This symposium highlighted 2 proteomic approaches, protein fingerprinting in complex mixtures with peptoid microarrays and top-down mass spectrometry for annotation of gene products. Likewise, an overview of the methodologies used in metabolomic profiling of natural products was presented, and an illustration of an integrated metabolomics approach in nutrition research was highlighted.

Anthocyanin-rich grape extract blocks breast cell DNA damage.

Anthocyanins, belonging to the flavonoid family of phytochemicals, have received attention as agents that may have potential in preventing chronic diseases such as cardiovascular diseases and certain cancers. In the present study, an anthocyanin-rich extract from Concord grapes [referred to as Concord grape extract (CGE)] and the anthocyanin delphinidin were evaluated for their capacity to inhibit DNA adduct formation due to the environmental carcinogen benzo[a]pyrene (BP) in MCF-10F cells, a noncancerous, immortalized human breast epithelial cell line. CGE at 10 and 20 microg/mL and delphinidin at 0.6 microM concentrations significantly inhibited BP-DNA adduct formation. This was associated with a significant increase in activities of the phase II detoxification enzymes glutathione S-transferase and NAD(P)H:quinone reductase 1. In addition, these grape components also suppressed reactive oxygen species (ROS) formation, but did not induce antioxidant response element-dependent transcription. Taken together, these data suggest that CGE and a component grape anthocyanin have breast cancer chemopreventive potential due in part to their capacity to block carcinogen-DNA adduct formation, modulate activities of carcinogen-metabolizing enzymes, and suppress ROS in these noncancerous human breast cells.

Sulforaphane suppresses angiogenesis and disrupts endothelial mitotic progression and microtubule polymerization.

Sulforaphane (SUL), an isothiocyanate derived from broccoli and other cruciferous vegetables, is known to induce phase II detoxification enzymes, disrupt cancer cell microtubule polymerization, and trigger cell cycle arrest in breast and colon cancer cells. Here, we provide the first evidence that SUL also acts to inhibit angiogenesis via suppression of endothelial cell proliferation. Bovine aortic endothelial (BAE) cells were exposed to concentrations of up to 15 microM SUL prior to cell cycle analysis and mitotic index quantification. Within 24 h, 15 microM SUL clearly induced G(2)/M accumulation and pre-metaphase arrest in BAE cells. Moreover, immunofluorescence tubulin staining indicated that this same SUL concentration was efficacious in not only disrupting mitotic progression, but also in perturbing normal polymerization of mitotic (and cytoplasmic) microtubules. Furthermore, daily administration of SUL (100 nmol/day, i.v. for 7 days) to female Balb/c mice bearing VEGF-impregnated Matrigel plugs strongly and significantly (P<0.05) suppressed angiogenesis progression as measured by hemoglobin concentration. Taken together, these findings suggest that the endothelial cell population is a novel target of SUL action both in vitro and in vivo. This mechanism of SUL-induced endothelial microtubule disruption and early mitotic arrest may further discern a potential role of SUL as a chemopreventive agent.

A novel synthetic analogue of a constituent of Isodon excisus inhibits transcription of CYP1A1, -1A2 and -1B1 by preventing activation of the aryl hydrocarbon receptor.

We investigated the effect of a novel synthetic analogue of a constituent from the Chinese medicinal herb Isodon excisus, 3-(3-methoxy-phenyl)-N-(3, 4, 5-trimethoxy-phenyl)-acrylamide (compound 343), on the carcinogen activation pathway mediated by the aryl hydrocarbon receptor (AhR) in human hepatoma HepG2 cells. We found that compound 343 inhibited the upregulation of cytochrome P-450 (CYP) enzyme activity in cells treated with the AhR ligands and potent carcinogens, dimethylbenz[a]anthracene (DMBA) or 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (TCDD). Compound 343 also inhibited the DMBA- or TCDD-induced increase in CYP1A1, -1A2 and -1B1 mRNA levels. Carcinogen-induced transcription of CYP genes was also suppressed by compound 343, as measured by a reporter gene controlled by the xenobiotic-responsive element (XRE). This was confirmed by measuring the amount of carcinogen-induced CYP1A1 heterogeneous nuclear RNA. Compound 343 blocked the DMBA- or TCDD-induced activation of the AhR DNA-binding capacity for the XRE, as measured by a chromatin immunoprecipitation assay. Compound 343 also inhibited CYP enzyme activity in microsomes isolated from DMBA- or TCDD-treated cells, as well as the activity of recombinant CYP1A1, -1A2 and -1B1, indicating that compound 343 directly inhibits CYP enzymes. These results indicate that compound 343 is both a potent inhibitor of carcinogen-induced CYP enzyme expression, as well as a direct inhibitor of CYP enzymes.

Genistein suppresses proliferation and MET oncogene expression and induces EGR-1 tumor suppressor expression in immortalized human breast epithelial cells.

Higher soy food intake has been hypothesized to be a major factor explaining the decreased breast cancer risk in Asian countries, compared to those regions of the world consuming predominantly Western-style diets. Consumption of soy isoflavones, particularly genistein, has received considerable attention as the soy component largely responsible for the protective effects hypothesized to result from soy food consumption. However, the impact of adult consumption of soy foods on breast cancer risk in pre-menopausal and menopausal women is not consistent. There are recent epidemiological reports that consumption of soy foods can most effectively reduce breast cancer risk when consumed early in life during the pre-pubertal or adolescent periods. The aim of the present study was to evaluate the effects of physiologically-relevant levels of genistein (0.5 microM and 1 microM), concentrations achievable in the plasma following soy food consumption, on proliferation and expression of select genes in the human breast epithelial cell model. Treatment of the non-neoplastic, immortalized human breast epithelial MCF-10F cells with these low concentrations of genistein was associated with decreased cell proliferation, down-regulation of the protooncogene MET, up-regulation of the breast tumor suppressor gene EGR-1, and up-regulation of the immediate-early response genes FOS and JUN. In addition, genistein treatment was associated with a significant increase in Egr-1 binding to the transcription factor Sp1. Taken together, these genistein-induced changes in gene expressions provide insights into potential mechanisms by which this isoflavone may protect human breast cells against neoplastic transformation.

Inhibition of Akt signaling and enhanced ERK1/2 activity are involved in induction of macroautophagy by triterpenoid B-group soyasaponins in colon cancer cells.

Triterpenoid B-group soyasaponins have been found to induce macroautophagy in human colon cancer cells at concentrations obtainable through consumption of legume foodstuffs. In the present studies the mechanism(s) for this autophagy-inducing action of soyasaponins was evaluated by measuring changes in signal transduction pathways associated with autophagy. Specifically, inhibition of the Akt signaling pathway and enhanced activity of ERK1/2 have previously been implicated in controlling induction of macroautophagy in mammalian cancer cells. Here we show that these pathways are also involved in B-group soyasaponin-induced macroautophagy, as changes in enzyme activities preceded significant increases in autophagic activity. The autophagic capacity of HCT-15 cells was significantly increased by 6 h post-saponin exposure, which led us to measure alterations in signaling events that preceded this time point. We determined that exposure to B-group soyasaponins suppressed Akt activity maximally by 50%, which was associated with a reduction in the activating phosphorylation of the Akt-serine473 residue. In addition, ERK1/2 activity was significantly increased by 60%, and was determined to be necessary for B-group soyasaponin-induced autophagy. The raf-1 kinase has been identified as a potential point of cross-talk between the Akt and ERK1/2 signaling cascades. Following B-group soyasaponin treatment activity of raf-1 was significantly increased by a maximal 200%, suggesting that this enzyme in part modulates the enhanced ERK1/2 activity. These results provide new insights into the signaling events that control induction of autophagy by B-group soyasaponins in human colon cancer cells and suggest that soyasaponins warrant further study as potential colon cancer chemopreventive agents.

Purple grape juice inhibits 7,12-dimethylbenz[a]anthracene (DMBA)-induced rat mammary tumorigenesis and in vivo DMBA-DNA adduct formation.

There has been considerable interest in identifying specific foods and phytochemicals that may have breast cancer preventive properties. Concord grapes are rich in polyphenolic chemicals and anthocyanin pigments that may have biological properties which could suppress cancer such as having antioxidant, antiproliferative, and proapoptotic actions. To determine the potential breast cancer protective action of purple grape juice, we examined the effect of grape juice consumption on the initiation stage of 7,12-dimethylbenz[a]anthracene (DMBA)-induced rat mammary tumorigenesis and on the in vivo formation of rat mammary DNA adducts in female Sprague-Dawley rats. Consumption of grape juice significantly inhibited mammary tumor mass at termination and the growth of tumors for the first 5 weeks of detectable tumor development. Consumption of grape juice phenolics by rats also significantly inhibited in vivo mammary DMBA-DNA adduct formation by 34 and 56% for animals fed phenolics at 346 and 692 mg/dL, respectively, compared to controls. Mammary 8-oxo-deoxyguanosine (8-oxo-dG) levels decreased by 25 and 37%, respectively, but the differences were not statistically significant. Liver DMBA-DNA adducts decreased by 10-30%, while 8-oxo-dG adducts remained unchanged, following grape juice intake. Liver glutathione S-transferase activity was significantly increased following grape juice consumption, but only at the highest level of intake. In addition, liver activities of catalase increased and xanthine oxidase decreased significantly, but only at the highest grape juice dose. Thus, these studies indicate that specific constituents or combinations of phytochemicals in purple grape juice can block the initiation stage of DMBA-induced rat mammary tumorigenesis. This tumor inhibitory effect was associated with a suppression of mammary DMBA-DNA adduct formation, which in part may be explained by increased liver activity of the phase II metabolizing enzyme, glutathione S-transferase. Mammary and liver 8-oxo-dG levels were not significantly altered by grape juice consumption. Thus, grape juice constituents appear to have benefit in decreasing susceptibility of the rat mammary gland to the tumor-initiating action of DMBA.

Induction of macroautophagy in human colon cancer cells by soybean B-group triterpenoid saponins.

The impact of triterpenoid saponins isolated from soybeans on suppression of colon cancer cell proliferation was evaluated. Experiments were conducted to determine the effects of a purified soybean B-group saponin extract on cell proliferation, cell-cycle distribution and programmed cell death in cultures of human HCT-15 colon adenocarcinoma cells. Treatment of cells with the soyasaponins at concentrations of 25-500 p.p.m. significantly reduced viable cell numbers after 24 and 48 h of exposure. Treatment of cells with 25 and 100 p.p.m. of saponins also resulted in a transient accumulation of cells in the S-phase of the cell cycle that was associated with a significant reduction of cyclin-dependant kinase-2 (CDK-2) activity. More striking was that, when examined by transmission electron microscopy, soyasaponin-treated cells exhibited an approximately 4.5-fold increase in cell morphologies characteristic of Type II non-apoptotic programmed cell death (PCD) including numerous autophagic vacuoles, changes that collectively suggest autophagic cell death. In addition, the protein levels of microtubule-associated protein light chain 3 (LC-3), a specific marker of macroautophagy, increased substantially following soyasaponin treatment. Taken together these results thus indicate that soybean saponins, at physiologically relevant doses, can suppress HCT-15 colon cancer cell proliferation through S-phase cell-cycle delay, and can induce macroautophagy, the hallmark of Type II PCD. These findings suggest that B-group soyasaponins may be another colon-cancer suppressive component of soy that warrants further examination as a potential chemopreventive phytochemical.

Sulforaphane inhibits human MCF-7 mammary cancer cell mitotic progression and tubulin polymerization.

Sulforaphane (SUL), an isothiocyanate derived from hydrolysis of glucoraphanin in broccoli and other cruciferous vegetables, was shown to induce phase II detoxification enzymes, inhibit chemically induced mammary tumors in rodents, and more recently, to induce cell cycle arrest and apoptosis in colon cancer cells. In the present study, we demonstrate that SUL also acts to inhibit proliferation of MCF-7 adenocarcinoma cells from the human breast. Treatment of synchronized MCF-7 cells with 15 micromol/L SUL resulted in significant (P < 0.05) G(2)/M cell cycle arrest (167% of control) and elevated cyclin B1 protein (175% of control) within 24 h. Moreover, 15 micromol/L SUL significantly (P < 0.05) induced phosphorylation of histone H1 (167% of control), blocked cells in early mitosis ( approximately 10-fold increase over control), and disrupted polymerization of mitotic microtubules in vivo. Subsequent exposure of purified bovine brain tubulin to relatively high doses of SUL significantly (P < 0.05) inhibited both tubulin polymerization rate (51% of control) and total tubulin polymerization (78% of control) in vitro. Additionally, polymerization of purified tubulin exposed to isothiocyanate-containing analogs of SUL was similarly inhibited. Taken together, these findings indicate that SUL has mammary cancer suppressive actions involving mitotic cell cycle arrest and suggest a mechanism linked to the disruption of normal tubulin polymerization and/or more subtle effects on microtubule dynamics.

Optical coherence tomography: feasibility for basic research and image-guided surgery of breast cancer.

Diagnostic trends in medicine are being directed toward cellular and molecular processes, where treatment regimens are more amenable for cure. Optical imaging is capable of performing cellular and molecular imaging using the short wavelengths and spectroscopic properties of light. Diffuse optical tomography is an optical imaging technique that has been pursued as an alternative to X-ray mammography. While this technique permits non-invasive optical imaging of the whole breast, to date it is incapable of resolving features at the cellular level. Optical coherence tomography (OCT) is an emerging high-resolution biomedical imaging technology that for larger and undifferentiated cells can perform cellular-level imaging at the expense of imaging depth. OCT performs optical ranging in tissue and is analogous to ultrasound except reflections of near-infrared light are detected rather than sound. In this paper, an overview of the OCT technology is provided, followed by images demonstrating the feasibility of using OCT to image cellular features indicative of breast cancer. OCT images of a well-established carcinogen-induced rat mammary tumor model were acquired. Images from this common experimental model show strong correlation with corresponding histopathology. These results illustrate the potential of OCT for a wide range of basic research studies and for intra-operative image-guidance to identify foci of tumor cells within surgical margins during the surgical treatment of breast cancer.

Ethanol inhibits benzo[a]pyrene-DNA adduct removal and increases 8-oxo-deoxyguanosine formation in human mammary epithelial cells.

The effect of ethanol and acetaldehyde treatment on the removal of benzo[a]pyrene diol-epoxide (BPDE)-DNA adducts in the immortalized, human mammary epithelial cell line MCF-10F was examined. Treatment of cells with 15 mM and 25 mM ethanol resulted in significantly more BPDE-DNA adducts/unit DNA remaining at multiple time points, compared to controls. The half-life of BPDE-DNA adducts in cells exposed to both 15 and 25 mM ethanol were 11.9 and 12.3 h, respectively, compared to a half-life of 9.8 h for the control cells. In contrast, for cells exposed to acetaldehyde at doses of 2.5 and 5.0 microM no significant trend in BPDE-DNA adduct persistence occurred, compared to controls. The inhibition of adduct removal for cells treated with ethanol was not associated with any changes in cell viability due to ethanol exposure. However, BP-treated cells exposed to 25 mM ethanol exhibited a significant 2-fold increase in 8-oxo-deoxyguanosine (8-oxo-deG) adducts compared to BP-treated cells alone. No significant increase in 8-oxo-deG was observed for cells treated with BP and exposed to 5.0 microM acetaldehyde. Thus, ethanol exposure of human mammary epithelial cells is associated with a decreased capacity to remove BPDE-DNA adducts. This inhibitory effect of ethanol on adduct removal in part may be related to ethanol-associated oxidative stress.

Sulforaphane: a naturally occurring mammary carcinoma mitotic inhibitor, which disrupts tubulin polymerization.

Sulforaphane (SUL), an isothiocyanate found in broccoli and other cruciferous vegetables, has been shown to induce phase II detoxification enzymes, inhibit chemically induced mammary tumors in rats, and more recently to induce cell cycle arrest and apoptosis in cancer cells of the colon. Here, we provide evidence that SUL also acts as a breast cancer anti-proliferative agent. The BALB/c mouse mammary carcinoma cell line F3II was treated with SUL at concentrations up to 15 microM and examined for markers of cell cycle arrest and apoptosis. Treatment of asynchronous F3II cells with 15 microM SUL resulted in G2/M cell cycle arrest, elevated p34cdc2 (cdc2) kinase activity, Bcl-2 down-regulation, evidence of caspase activation, and aggregation of condensed nuclear chromatin. Subsequent exposure of synchronized cells to 15 microM SUL resulted in elevated numbers of prophase/prometaphase mitotic figures, indicating cell cycle progression beyond G2 and arrest early within mitosis. Moreover, cells treated with 15 microM SUL displayed aberrant mitotic spindles, and higher doses of SUL inhibited tubulin polymerization in vitro. In addition, BALB/c mice injected s.c. with F3II cells and subsequently injected daily i.v. with SUL (15 nmol/day for 13 days) developed significantly smaller tumors (approximately 60% less in mass) than vehicle-treated controls. Western blot analysis of tumor proteins demonstrated significantly (P<0.05) reduced PCNA and elevated PARP fragmentation in samples from animals dosed with SUL. Taken together, these results indicate that SUL has mammary cancer suppressive actions both in cell culture and in the whole animal. Inhibition of mammary carcinogenesis appears in part to involve perturbation of mitotic microtubules and early M-phase block associated with cdc2 kinase activation, indicating that cells arrest prior to metaphase exit.