Chung S. Park

Maternal high-methyl diet suppresses mammary carcinogenesis in female rat offspring

Maternal nutrition during pregnancy influences the development and metabolism of the fetus. Recent studies suggest that the cancer risk of offspring later in life is associated with maternal diet, but little is known about the effect of a maternal diet high in methyl nutrients on breast cancer risk. Lipotropes are methyl group-containing essential nutrients (methionine, choline, folate and vitamin B(12)) that play key roles in one-carbon metabolism. In this study, we investigated the long-term effects of maternal dietary high-dose lipotropes (five times higher than in the control diet) on the development and progression of mammary tumors in rat offspring using two separate experiments (in utero exposure with and without postnatal supplementation). In both experiments, the female offspring were injected intraperitoneally with a single dose (50 mg/kg body wt) of N-nitroso-N-methylurea during puberty to induce mammary tumors. Tumor growth and development were recorded, and at the end of the study, tissues were collected for analysis. For both experiments, the offspring from dams fed a high-dose lipotropes showed significantly decreased tumor incidence, tumor multiplicity and tumor volume, while also displaying a significant increase in survival rate and tumor latency. Gene transcription analysis, as measured by quantitative real-time PCR, revealed a significant decrease of histone deacetylase 1 (Hdac1) messenger RNA in mammary tumors in both experiments. Our findings provide evidence that maternal dietary high-dose lipotropes reduce mammary carcinogenesis in offspring in association with long-term alterations in gene expression and may be useful in developing maternal dietary strategies to prevent breast cancer.

Canola Oil Inhibits Breast Cancer Cell Growth in Cultures and In Vivo and Acts Synergistically with Chemotherapeutic Drugs

Certain fatty acids in canola oil (CAN) have been associated with a reduced risk of breast cancer. This study assessed the effects of CAN on proliferation and death of human breast cancer cells in vitro and in vivo in chemically induced mammary carcinogenesis. We hypothesize that CAN reduces breast cancer cell growth by inducing cell death. In a series of in vitro experiments, human breast cancer T47D and MCF-7 cells were cultured and treated with CAN and two chemotherapeutic drugs, tamoxifen and cerulenin. Cell proliferation and caspase-3 and p53 activities were measured. Reduced cancer cell growth and increased expression of caspase-3 and p53 were seen in T47D and MCF-7 cells treated with CAN. Moreover, CAN showed synergistic cancer cell growth inhibition effects with tamoxifen and cerulenin. In a subsequent live animal experiment, 42 female Sprague–Dawley rats were randomly assigned to corn oil (CORN) or CAN diets, and mammary tumors were chemically induced by N-nitroso-N-methylurea. CAN-dieted rats had reduced tumor volumes and showed an increased survival rate as compared to CORN-dieted rats. We demonstrated that CAN has suppressive effects on cancer growth, and reduces tumor volumes. The results suggest that CAN may have inhibitory effects on breast cancer cell growth, and warrants further investigation of the synergistic effects of CAN with anti-cancer drugs.

Waxy corn as a replacement for dent corn for lactating dairy cows

Abstract Waxy and dent corn starch differences were compared in diets of early lactating dairy cows. Thirty multiparous Holsteins averaging 568±76 kg body weight (BW) and 50±24 d in lactation were randomly assigned at two locations to three treatments to evaluate: (1) the extent to which replacing dent corn in the diet with recently developed waxy hybrids affects milk yield and composition; and (2) to document changes in the concentration of blood and ruminal metabolites of dairy cattle fed waxy corn compared to dent corn. A 3×3 Latin square design was used to test the treatments: control, (100% dent corn in grain mix), dent+waxy (50% dent and 50% waxy corn in grain mix), and waxy corn (100% in grain mix). Total mixed rations (TMR) formulated to be isonitrogenous at 17.2% crude protein and isocaloric at 1.72 Mcal net energy for lactation per kg of DM, were fed twice daily to individual cows in Calan gates (North Dakota State University Dairy Research Center) or in tie stalls (University of Minnesota, Crookston Dairy Research Center) for 15 weeks. Rumen, blood and milk samples were collected during the fifth week of each period. Ruminal acetate, isobutyrate, isovalerate and total volatile fatty acid (VFA) concentrations were lower (P 0.05) by treatment. There was no difference in milk yield or total milk solids indicating similar lactational performance among treatments using waxy and dent corn.

Lipotrope‐modified diets enhance nitrosomethylurea‐induced mammary carcinogenesis in female rats

This study was conducted to determine the effects of lipotrope-modified (deficient or supplemented) diets on nitrosomethylurea- (NMU) induced mammary tumorigenesis. Eighty female Sprague-Dawley rats (4 wks old) were assigned to one of the following groups: control-synthetic diet (CSD), containing all required lipotropes; choline-methionine-deficient diet (CMD); methyl-deficient diet (MDD), lacking all lipotropes; and methyl-supplemented diet (MSD), containing twice as much of each lipotrope as the CSD diet. All animals were injected with NMU after a three-week dietary treatment period. MDD and MSD groups had shorter tumor latency periods (73 and 74 days, respectively) than the CSD group (105 days). Number of tumors per rat was significantly increased in the MDD group (4.6) compared with CSD (1.6), CMD (2.1), and MSD (2.5) groups. The results indicate that dietary manipulation of lipotropes in young female rats enhanced NMU-induced mammary tumorigenesis.

Methyl-donor nutrients inhibit breast cancer cell growth

Lipotropes (methyl group containing nutrients, including methionine, choline, folate, and vitamin B12) are dietary methyl donors and cofactors that are involved in one-carbon metabolism, which is important for genomic DNA methylation reactions and nucleic acid synthesis. One-carbon metabolism provides methyl groups for all biological methylation pathways and is highly dependent on dietary supplementation of methyl nutrients. Nutrition is an important determinant of breast cancer risk and tumor behavior, and dietary intervention may be an effective approach to prevent breast cancer. Apoptosis is important for the regulation of homeostasis and tumorigenesis. The anti-apoptotic protein Bcl-2 may be a regulatory target in cancer therapy; controlling or modulating its expression may be a therapeutic strategy against breast cancer. In this study, the effects of lipotrope supplementation on the growth and death of human breast cancer cell lines T47D and MCF-7 were examined and found to inhibit growth of both T47D and MCF-7 cells. Furthermore, the ratios of apoptotic cells to the total number of cells were approximately 44% and 34% higher in the lipotrope-supplemented treatments of T47D and MCF-7 cancer cells, respectively, compared with the control treatments. More importantly, Bcl-2 protein expression was decreased by approximately 25% from lipotrope supplementation in T47D cells, suggesting that lipotropes can induce breast cancer cell death by direct downregulation of Bcl-2 protein expression. Cancer treatment failure is often correlated with Bcl-2 protein upregulation. These data may be useful in the development of effective nutritional strategies to prevent and reduce breast cancer in humans.

Maternal Dietary Canola Oil Suppresses Growth of Mammary Carcinogenesis in Female Rat Offspring

As suggested by rodent studies and studies using human breast cancer cells, dietary canola oil is linked with lower breast cancer risk. Here, we investigated the effect of maternal (pregnancy plus lactation) dietary canola oil on the susceptibility of female Sprague-Dawley rat offspring to mammary carcinogenesis. Although the control diet had 10% soybean oil, the treatment diet was formulated to contain 10% canola oil as a fat source. N-nitroso-N-methylurea was injected to induce mammary cancer in offspring. The offspring of canola-fed dams showed significantly decreased tumor multiplicity (1.0 ± 0.3 vs. 1.9 ± 0.3, respectively; P = 0.04) and tumor volume (1232.5 ± 771.0 mm3 vs. 6,302.5 ± 1,747.4 mm3, respectively; P = 0.01), along with increased survival rate (87% vs. 47%, respectively; P = 0.01). In addition, the mRNA expression of development-related gamma-glutamyltransferase 1 was significantly higher in the lactating mammary tissues of the canola group dams and mammary tumor tissues of the offspring [2.5 ± 0.6 vs. 0.5 ± 0.2, respectively (P = 0.01) and 0.98 ± 0.03 vs. 0.56 ± 0.15, respectively (P = 0.05)]. These results suggest a potential anticancer effect of maternal dietary canola oil and may be useful in devising prenatal nutritional strategies to reduce breast cancer risk in humans.

Dietary lipotrope-mediated mammary carcinogenesis in female rats

Abstract Dietary deficiency of lipotropes is known to be carcinogenic in itself. This study examined 1) the susceptibility of female rats previously exposed to lipotrope-modified diets to nitrosomethylurea (NMU)-induced mammary carcinogenesis; and 2) how lipotrope-modified diets modulate DNA methylation and gene expression in mammary tissue. Female rats (36 d of age) were assigned to one of the following groups: control-synthetic diet (CSD), containing all required lipotropes; methyl-deficient diet (MDD), lacking all lipotropes; and methyl-additive diet (MAD), containing 1.5-fold the amount of each lipotrope as in CSD. Rats were injected with NMU after a 2-wk dietary treatment period, and 2 d after NMU administration all treatment groups were fed CSD for the remaining experimental period. Mammary tissues were collected from rats just prior to NMU administration. The MDD group had the shortest latency period. The number of tumors and tumor volume were greatest in the MDD rats. Dietary modification of lipotropes altered the DNA methylation pattern of ornithine decarboxylase gene. DNA was significantly hypomethylated in mammary tissues of the MDD rats. These results suggest that dietary deficiency of lipotropes led to changes in DNA methylation and enhanced NMU-induced mammary carcinogenesis.

METHIONINE CYTOTOXICITY IN THE HUMAN BREAST CANCER CELL LINE MCF-7

SummaryAmong the first nutrients to be linked to cancer were methyl group containing nutrients including methionine. Methionine and its metabolic derivatives are essential components in several indispensable biological reactions including protein synthesis, polyamine synthesis, and many transmethylation reactions. The purpose of this study was to determine the extent to which methionine excess affects the proliferation and gene expression of the human breast cancer cell line MCF-7. Cells were first grown in control medium; the medium was then replaced with either control or methionine-supplemented treatment media. We found that 5 and 10 g/L methionine significantly suppressed cell growth on day 1, and no further growth was detected after 3 d of treatment. Cell, proliferation in the methionine treated group was significantly lower than that of the control group. Northern analysis revealed that expression of p53 in methionine-treated MCF-7 cells was approximately 70% lower than that of control cells. p53 is a key cell cycle regulatory, protein that has been implicated in tumorigenesis and cancer progression. Alteration of the p53 tumor suppressor gene is the most common genetic change found in a wide variety of malignancies, including cancer. This study shows that excess methionine (5 g/L) inhibited proliferation of MCF-7 breast cancer cells, and down regulation of p53 is correlated with this inhibition. These findings may aid in the development of nutritional strategies for breast cancer therapy.

Lipotrope deficiency inhibits cell growth and induces programmed cell death in human breast cancer cell line MCF‐7

To determine the effects of lipotrope modification on breast cancer cell growth and cell death, the human breast cancer cell line MCF-7 was assigned to grow in one of three lipotrope treatment media for four days. The treatment media included lipotrope-control medium (LCM), containing all required lipotropes; lipotrope-deficient medium (LDM), lacking all lipotropes but supplying homocysteine instead; and lipotrope-additive medium (LAM), containing twice as much of each lipotrope as LCM. Cell count and [3H]thymidine incorporation into DNA revealed that LDM slowed cell growth and inhibited cell proliferation in the MCF-7 cell line. Gel electrophoresis showed significant DNA degradation with the appearance of fragments in LDM-treated cells, whereas the DNA in LCM and LAM cells was largely intact. The LDM group displayed more apoptotic bodies as detected by in situ immunohistochemistry. The gene expression level of bcl-2 was lower in cells treated with LDM than in those treated with LCM and LAM, whereas p53 gene expression did not appear different among the three treatment groups. It is concluded that lipotrope deficiency inhibits cell growth and induces programmed cell death in the human breast cancer cell line MCF-7.

LIPOTROPES REGULATE BCL-2 GENE EXPRESSION IN THE HUMAN BREAST CANCER CELL LINE, MCF-7

SummaryLipotropes, a methyl group containing nutrients, including choline, methionine, folic acid, and vitamin B12, are essential nutrients for humans. They are important methyl donors that interact in the metabolism of one-carbon units and are essential for the synthesis and methylation, of deoxyribonucleic acid. The purpose of this study was to examine the effects of excess lipotropes on the growth of a human breast cancer cell line, MCF-7, and normal mammary cells, MCF-10A, in culture. Both cell lines were grown in basal culture medium for 24 h and then switched to medium supplemented with 50 times the amount of each lipotrope as basal culture medium (control). Although there were no significant differences in growth between treatments in either cell line, gene array and Northern analysis revealed that expression of bcl-2 was decreased in lipotrope-treated MCF-7 cells. The ability to induce tumor, cell death could have many uses in the prevention and treatment of cancer. Bcl-2 regulates apoptosis and has been shown to directly affect the sensitivity of cancer cells to chemotherapy agents, and it is suggested that strategies designed to block Bcl-2 might prove useful in sensitizing tumor cells to chemotherapy-induced apoptosis. This study shows that although excess lipotropes do not inhibit the growth of breast cancer cells, they can down-regulate the bcl-2 gene, suggesting that lipotropes may increase the susceptibility of breast cancer cells to anticancer drugs.