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Expression profiling by RNA-Seq of breast cancer samples from patients in walnut-consuming and control groups

ABSTRACT: Consumption of walnuts has slowed breast cancer growth and/or reduced the risk of breast cancer in mice. The significantly reduced mean tumor size or numbers of tumors was associated with changing the expressions of many genes that are associated with cancer growth, survival and metastasis. Many women treated for breast cancer are interested in reducing the risk for recurrence. The study was a non-placebo, two-arm, clinical trial. Women with lumps large enough for research and pathology biopsies were recruited to the trial. One or two additional biopsies were taken for gene expression analyses using next generation RNA Sequencing methods. The subjects randomized to the walnut group immediately began to consume 2 ounces of walnuts per day until follow-up surgery, if surgery were needed. At follow up surgery, additional biopsies were taken from the surgically removed, cancerous tissue for additional gene expression analyses. Changes in gene expression compared to baseline were determined in tumors of each individual woman in walnut-consuming and control groups.

ORGANISM(S): Homo sapiens

PROVIDER: GSE111073 | GEO | 2019/03/10

REPOSITORIES: GEO

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Project description:Introduction Mammographic density (MD), as assessed from film screen mammograms, is determined by the relative content of adipose, connective and epithelial tissue in the female breast. In epidemiological studies, a high percentage of MD confers a four to six fold risk elevation of developing breast cancer, even after adjustment for other known breast cancer risk factors. However, the biologic correlates of density are little known. Methods Gene expression analysis using whole genome arrays was performed on breast biopsies from 143 women; 79 women with no malignancy (healthy women) and 64 newly diagnosed breast cancer patients, both included from mammographic centres. Percent MD was determined using a previously validated, computerized method on scanned mammograms. Significance analysis of microarrays (SAM) was performed to identify genes influencing MD and generalized regression models were used to assess the independent contribution from different variables to MD. Results SAM-analysis identified 24 genes differentially expressed between samples from breasts with high and low MD. These genes included three uridine 5'-diphospho-glucuronosyltransferase (UGT) genes and the oestrogen receptor gene (ESR1). These genes were down-regulated in samples with high MD compared to those with low MD. The UGT gene products, which are known to inactivate oestrogen metabolites, were also down-regulated in tumour samples compared to samples from healthy individuals. Several single nucleotide polymorphisms (SNPs) in the UGT genes associated with the expression of UGT and other genes in their vicinity were identified. Conclusions Three UGT enzymes were lower expressed both in breast tissue biopsies from healthy women with high MD and in biopsies from newly diagnosed breast cancers. The association was strongest among young women and women using hormonal therapy. UGT2B10 predicts MD independently of age, hormone therapy and parity. Our results indicate that down-regulation of UGT genes in women exposed to female sex hormones is associated with high MD and might increase the risk of breast cancer. Gene expression analysis of breast biopsies from 143 women, 79 non-cancer (healthy women with no cancer who had a mammogram taken) and 64 breast cancer.

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Expression profiling by RNA-Seq of breast cancer samples from patients in walnut-consuming and control groups

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