Unknown,Transcriptomics,Genomics,Proteomics

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The effect of dietary CLA on mammary tumorigenesis

ABSTRACT: Conjugated linoleic acid (CLA), a class of fatty acids found in beef and dairy products, has been shown to inhibit tumorigenesis in a variety of cancer model systems. Based on previously well-documented anti-tumor activity of CLA in rodent models of breast cancer, a pilot study was initiated to examine the effect of dietary CLA in a well-established transgenic model of breast cancer. Western blots were performed for the detection of AKT, c-Src, ERK1/2, and Cdc24. CLA significantly increased tumor burden (p<0.1) independent of an increase in oncogenic signaling. Mammary gland whole mounts indicated a loss of mammary adipose and extensive epithelial expansion in CLA-treated animals. Microarray analysis indicated a significant reduction in cytoskeletal related genes with at least a two-fold decrease in five out of six CLA-fed animals compared to untreated controls. Reduction of Cdc42, a key regulator of cell adhesion and cytoskeletal arrangements, was confirmed at the protein level by western blot (p<0.01). These findings suggest that dietary CLA may advance the malignant phenotype by promoting a loss of cell polarity and adhesion in the mammary gland epithelium. This action may have serious clinical implications for a subset high-risk population and warrants further investigation. Virgin, four-week-old PyV-mT mice were administered a diet of a mixed-isomer CLA formulation (1% wt/wt) (N=6) or control AIN96G diet (N=5) for four weeks. Measurements of food disappearance, weights and palpations were recorded weekly. All animals were euthanized at eight weeks of age. Formalin-fixed, paraffin-embedded mammary gland tissue was used for H&E and trichrome staining and immunohistochemistry for Ki67. Tissue levels of CLA were measured by gas chromatography. Thoracic mammary glands were fixed in glacial acetic acid:ethanol and carmine stained. cDNA microarray was performed on RNA from 6 CLA-fed mice and 4 control mice using the Affymetrix 430 2.0 mouse genome chips.

ORGANISM(S): Mus musculus

SUBMITTER: Margaret Flowers

PROVIDER: E-GEOD-13553 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Pilot study on the effects of dietary conjugated linoleic acid on tumorigenesis and gene expression in PyMT transgenic mice.

Flowers Margaret M Schroeder Joyce A JA Borowsky Alexander D AD Besselsen David G DG Thomson Cynthia A CA Pandey Ritu R Thompson Patricia A PA

Carcinogenesis 20100711 9

Conjugated linoleic acid (CLA) is a class of commercially available fatty acids that have been associated with anticancer properties in rodent models of chemical carcinogenesis. We conducted a pilot study to examine the antitumor effect of dietary CLA in a polyoma virus-middle T antigen (PyMT) mouse model of invasive breast cancer. Virgin 4-week-old PyMT mice were administered a mixed-isomer CLA diet (1% wt/wt) or control AIN-93G diet for 4 weeks (N = 6 and 5, respectively) and tumor burden was ...[more]

PMID: 20624750

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Project description:Overexpression of fatty acid synthase (FAS) has been reported in both malignant and premalignant breast lesions, and has been associated with poor outcome. FAS has gained interest as a metabolic target for the treatment of breast cancer based on evidence that blockade with the antifungal antibiotic, cerulenin or synthetic inhibitor C75 inhibits proliferation of breast cancer cells and delays tumor development. Conjugated linoleic acid (CLA), a class of fatty acids found in beef and dairy products, has been shown to inhibit FAS in bovine mammary adipose. Based on previously well-documented anti-tumor activity of CLA, we hypothesized that one mechanism of CLAâs anti-tumorigenic activity may be metabolic blockade of FAS. We fed virgin PyV-MT transgenic mice a diet supplemented with either 1% CLA, as mixed isomers, or control chow for four weeks. Tissue histology was determined by H&E staining. cDNA microarray and real-time quantitative PCR were performed to determine relative expression of lipogenic genes. Western blots were used to examine relative protein expression of FAS. Differences in protein densitometry were analyzed using Students 2-sided T-test. Probability was determined using the binomial sign test. Level of significance for all tests was 0.05. H&E staining revealed a shift towards advanced mammary lesions in the CLA-fed mice compared to control animals (24/26 vs. 11/26) (p for trend < 0.001). Microarray analysis revealed a >2-fold decrease in FAS in the CLA-fed group compared to controls, and was confirmed by quantitative RT-PCR (p < 0.001) and Western blot. The decrease in FAS mRNA expression was unexpectedly associated with more advanced disease (p for trend < 0.01). Conclusions: Dietary CLA suppressed fatty acid synthase in the mammary glands of the PyV-MT mouse while promoting mammary tumor progression. Experiment Overall Design: PyV-MT and wild type FVB mice were obtained from Jackson Laboratories (Bay Harbor, ME) and housed 2â4 per cage in micro insulator rooms. Mice were genotyped according to Jackson Laboratory protocols (http://jaxmice.jax.org/pub-cgi/protocols/protocols). PyV-MT positive females were randomly selected at four weeks of age to receive either a control AIN93G chow (n=5) or 1% CLA-supplemented chow (n=6). . Food disappearance and animal weights were recorded weekly. Animals were palpated three times a week, and tumor area (length x width) was measured by caliper. Only palpable masses with an area >/= 0.5 cm2 were considered established growths. Animals were euthanized by CO2 inhalation. Eight-week-old animals were selected for tissue histology and analysis of mRNA and protein expression. Mammary gland sections were collected and processed to obtain mRNA or protein lysate, paraffin embedded for histology, or stored in liquid nitrogen until further processing.

Project description:The present experiments were performed to determine the roles of estrogen receptors M-NM-1 and M-NM-2 (ERM-NM-1 and ERM-NM-2) in normal and neoplastic development in the mouse mammary gland. In wild-type mice, in vivo administration of estradiol (E) + progesterone (P) stimulated mammary ductal growth and alveolar differentiation. Mammary glands from mice in which the ERM-NM-2 gene has been deleted (M-NM-2ERKO mice) demonstrated normal ductal growth and differentiation in response to E + P. By contrast, mammary glands from mice in which the ERM-NM-1 gene has been deleted (M-NM-1ERKO mice) demonstrated only rudimentary ductal structures that did not differentiate in response to E + P. EGF demonstrates estrogen-like activity in the mammary glands of M-NM-1ERKO mice: treatment of M-NM-1ERKO mice with EGF + P (without E) supported normal mammary gland development, induced expression of progesterone receptor (PR), and increased levels of G- protein-coupled receptor (GPR30) protein. Mammary gland development in M-NM-2ERKO mice treated with EGF + P was comparable to that of wild-type mice receiving EGF + P; EGF had no statistically significant effects on the induction of PR or expression of GPR30 in mammary glands harvested from either wild-type mice or M-NM-2ERKO mice. In vitro exposure of mammary glands to 7,12-dimethylbenz[a]anthracene (DMBA) induced preneoplastic mammary alveolar lesions (MAL) in glands from wild-type mice and M-NM-2ERKO mice, but failed to induce MAL in mammary glands from M-NM-1ERKO mice. Microarray analysis of DMBA-treated mammary glands identified 28 functional pathways whose expression was significantly different in M-NM-1ERKO mice versus both M-NM-2ERKO and wild-type mice; key functions that were differentially expressed in M-NM-1ERKO mice included cell division, cell proliferation, and apoptosis. The data demonstrate distinct roles for ERM-NM-1 and ERM-NM-2 in normal and neoplastic development in the mouse mammary gland, and suggest that EGF can mimic the ERM-NM-1-mediated effects of E in this organ. Gene expression of mammary gland organ culture and DMBA-induced lesions from 4 mouse strains.

Project description:Background: The differential expression pattern of microRNAs (miRNAs) during mammary gland development might provide insights into their role in regulating the homeostasis of the breast epithelium. Our aim was to analyse these regulatory functions by deriving a comprehensive tissue-specific combined miRNA and mRNA expression profile of post-natal mouse mammary gland development. We measured the expression of 318 individual murine miRNAs by bead-based flow-cytometric profiling of whole mouse mammary glands throughout a 16-point developmental time course, including juvenile, puberty, mature virgin, gestation, lactation, and involution stages. In parallel whole-genome mRNA expression data were obtained. Results: One third (n = 102) of all murine miRNAs analysed were present during mammary gland development. MicroRNAs were represented in seven temporally co-expressed clusters, which were enriched for both miRNAs belonging to the same family and breast cancer-associated miRNAs. Global miRNA and mRNA expression was significantly reduced during lactation and the early stages of involution after weaning. For most detected miRNA families we did not observe systematic changes in the expression of predicted targets. For miRNA families whose targets did show significant changes, we observed inverse patterns of miRNA and target expression. The datasets are made publicly available and the combined expression profiles represent an important community resource for mammary gland biology research. Conclusions: MicroRNAs were expressed in co-regulated clusters during mammary gland development. Breast cancer-associated miRNAs were significantly enriched in these clusters. The mechanism and functional consequences of this miRNA co-regulation and its correlation with mRNA expression provide new avenues for research into mammary gland biology and generates candidates for functional validation. This SuperSeries is composed of the following subset Series: GSE15054: Characterisation of microRNA expression in post-natal mouse mammary gland development [gene] GSE15055: Characterisation of microRNA expression in post-natal mouse mammary gland development [miRNA] Refer to individual Series

Project description:Identify gene expression changes in the absence of Plk2 Disruptions in polarity and mitotic spindle orientation contribute to the progression and evolution of tumorigenesis. However, little is known about the molecular mechanisms regulating these processes in vivo. Here we demonstrate that Polo-like kinase 2 (Plk2) regulates mitotic spindle orientation in the mammary gland and is a putative tumor suppressor. Plk2 is highly expressed in the mammary gland and is required for proper mammary gland development. Loss of Plk2 leads to increased mammary epithelial cell proliferation and ductal hyperbranching. Additionally a novel role for Plk2 in regulating the orientation of the mitotic spindle and maintaining proper cell polarity in the ductal epithelium was discovered. In support of a tumor suppressor function for Plk2, loss of Plk2 increased the formation of lesions in multiparous glands. Collectively, these results demonstrate a novel role for Plk2 in regulating mammary gland development and as a tumor suppressor in mammary tumorigenesis. Disruptions in polarity and mitotic spindle orientation contribute to the progression and evolution of tumorigenesis. However, little is known about the molecular mechanisms regulating these processes in vivo. Here we demonstrate that Polo-like kinase 2 (Plk2) regulates mitotic spindle orientation in the mammary gland and is a putative tumor suppressor. Plk2 is highly expressed in the mammary gland and is required for proper mammary gland development. Loss of Plk2 leads to increased mammary epithelial cell proliferation and ductal hyperbranching. Additionally a novel role for Plk2 in regulating the orientation of the mitotic spindle and maintaining proper cell polarity in the ductal epithelium was discovered. In support of a tumor suppressor function for Plk2, loss of Plk2 increased the formation of lesions in multiparous glands. Collectively, these results demonstrate a novel role for Plk2 in regulating mammary gland development and as a tumor suppressor in mammary tumorigenesis. Comparison between Plk2 +/+ (n=3) and Plk2 -/- (n=3) mouse mammary epithelial cells

Dataset Information

The effect of dietary CLA on mammary tumorigenesis

Publications

Pilot study on the effects of dietary conjugated linoleic acid on tumorigenesis and gene expression in PyMT transgenic mice.

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