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Biomarkers of dietary energy restriction in women at increased risk of breast cancer

ABSTRACT: Dietary energy restriction (DER) reduces risk of spontaneous mammary cancer in rodents. In humans, DER in premenopausal years seems to reduce risk of postmenopausal breast cancer. Markers of DER are required to develop acceptable DER regimens for breast cancer prevention. We therefore examined markers of DER in the breast, adipose tissue, and serum. Nineteen overweight or obese women at moderately increased risk of breast cancer (lifetime risk, 1 in 6 to 1 in 3) ages between 35 and 45 were randomly allocated to DER [liquid diet, 3,656 kJ/d (864 kcal/d); n = 10] or asked to continue their normal eating patterns (n = 9) for one menstrual cycle. Biopsies of the breast and abdominal fat were taken before and after the intervention. RNA was extracted from whole tissues and breast epithelium (by laser capture microdissection) and hybridized to Affymetrix GeneChips. Longitudinal plasma and urine samples were collected before and after intervention, and metabolic profiles were generated using gas chromatography-mass spectrometry. DER was associated with significant reductions in weight [-7.0 (+/-2.3) kg] and in alterations of serum biomarkers of breast cancer risk (insulin, leptin, total and low-density lipoprotein cholesterol, and triglycerides). In both abdominal and breast tissues, as well as isolated breast epithelial cells, genes involved in glycolytic and lipid synthesis pathways (including stearoyl-CoA desaturase, fatty acid desaturase, and aldolase C) were significantly down-regulated. We conclude that reduced expressions of genes in the lipid metabolism and glycolytic pathways are detectable in breast tissue following DER, and these may represent targets for DER mimetics as effective chemoprophylactic agents Transcriptomic and Metabolomic intervention study of continuous energy restriction in 19 participants

ORGANISM(S): Homo sapiens

PROVIDER: GSE66159 | GEO | 2016/07/13

SECONDARY ACCESSION(S): PRJNA275989

REPOSITORIES: GEO

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Project description:Lymphocyte and breast tissue samples from overweight woman at increased risk of breast cancer before and after 1 month of intermittant energy restriction Introduction Observational studies indicate that weight loss and energy restriction reduce breast cancer risk. Intermittent energy restriction (IER) reduces weight as well as, or more than continuous energy restriction (CER), but its effect on the breast and systemic metabolism as indicators of breast cancer risk are not known. Methods We assessed the effect of IER ( 2 days of 65% energy restriction) for one menstrual cycle on the breast (breast gene expression and fat cell size) and systemic metabolism (insulin resistance, lipids, serum and urine metabolites) in 23 overweight premenopausal women at high risk of breast cancer. Unsupervised hierarchical analysis selected 100 genes with the highest variance between pre and post IER biopsies in 20 subjects, whilst mass spectrometry was used to assess corresponding changes in serum (LCMS) and urine metabolites (GCMS) in 23 subjects in the restricted and unrestricted days of the IER. Results Women lost on average 4.8% (± 2.0) of body weight and 8.0% (± 5.0) of body fat. Insulin resistance (HOMA) was reduced by 29.8% (±17.8) on the restricted days and by 11%(±34) on the unrestricted days of the IER. Over 250 serum and urine metabolites significantly increased or decreased during the two restricted days and most returned to normal after the subsequent five day period . In the breast tissue, approximately half (In 11) of the subjects displayed down regulation of several metabolic pathways including lipid synthesis, growth factors and hormones, whilst epithelial genes including milk proteins, secretoglobulins and mucins were up-regulated and several metabolic pathways down-regulated including lipid synthesis, growth factors and hormones. In the other nine subjects there was no appreciable effect of IER on the breast. CorrespondingThe gene changes were not seen in peripheral blood lymphocytes, and there was no reduction in breast fat cell size. The two groups defined by change in gene expression or lack of it did not differ in the degree of weight or fat loss, other systemic metabolic markers, or histological assessment of the biopsies. Conclusion We conclude that breasts vary in response to short-term IER, the mechanism of which requires further investigation. Trial registration ISRCTN77916487

Project description:Many cancers rely on glycolytic metabolism to fuel rapid proliferation. This has spurred interest in designing drugs that target tumor glycolysis such as AZD3965, a small molecule inhibitor of Monocarboxylate Transporter 1 (MCT1) currently undergoing Phase I evaluation for cancer treatment. Since MCT1 mediates proton-linked transport of monocarboxylates such as lactate and pyruvate across the plasma membrane (Halestrap and Meredith, 2004), AZD3965 is thought to block tumor growth through disruption of lactate transport and glycolysis. Here we show that MCT1 inhibition impairs proliferation of glycolytic breast cancer cells that express MCT4 via disruption of pyruvate rather than lactate export. We found that MCT1 expression is elevated in glycolytic breast tumors and cell lines as well as in malignant breast and lung tissues. High MCT1 expression predicts poor prognosis in breast and lung cancer patients. Stable knockdown and AZD3965-mediated inhibition of MCT1 promote oxidative metabolism. Acute inhibition of MCT1 reduces pyruvate export rate but does not consistently alter lactate transport or glycolytic flux in breast cancer cells that also express MCT4. Despite the lack of glycolysis impairment, MCT1 loss-of-function decreases breast cancer cell proliferation and blocks growth of mammary fat pad xenograft tumors. Our data suggest that MCT1 expression is elevated in glycolytic cancers to promote pyruvate export, which when inhibited enhances oxidative metabolism and reduces proliferation. This study presents an alternative molecular consequence of MCT1 inhibitors that further supports their use as anti-cancer therapeutics. Since MCT1 levels are elevated in glycolytic and malignant breast tumors, we hypothesized that MCT1 may contribute to the Warburg effect metabolic phenotype. To test this hypothesis, we generated whole genome microarray data from breast cancer cell lines either a) expressing a short hairpin (sh)RNA-mediated stable knockdown of MCT1; or b) treated for 24 hours with an MCT1 inhibitor (AZD3965). Scramble shRNA or DMSO were used as controls, and all conditions were analzed in triplicate. The cell lines used â HS578T, SUM149PT, and SUM159PT â are among the most glycolytic in a panel of 31 breast cancer cell lines.

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Biomarkers of dietary energy restriction in women at increased risk of breast cancer

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