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Estrogen receptor and mTOR signaling rewires cancer metabolism in obesity-associated breast cancer

ABSTRACT: Obesity is a risk factor for postmenopausal ERα (+) breast cancer. Molecular mechanisms activated by the factors from serum that contribute to this risk and how these mechanisms affect ERα signaling are yet to be elucidated. To identify such mechanisms, we performed whole metabolite and protein profiling in serum samples, which enabled us to focus on factors that were differentially present in serum from cancer-free vs. breast cancer susceptible and obese vs. non-obese post-menopausal women. These studies combined with in vitro assays identified free fatty acids (FFAs), as serum factors that correlate with increased proliferation and aggressiveness in ERα(+) breast cancer cells by. FFAs activated both ERα and mTOR pathways and rewired metabolism in breast cancer cells. Pathway preferential estrogen-1 (PaPE-1), which target ERα and mTOR signaling, was able to block changes induced by FFAs. In fact, PaPEs were more effective in the presence of FFAs, suggesting a role for obesity-associated gene and metabolic rewiring in providing new targetable vulnerabilities for ERα-(+) breast cancer in postmenopausal women. Our findings provide a basis for preventing or inhibiting obesity-associated breast cancer by using PaPEs that would reverse these newly appreciated metabolic properties of breast tumors in obese postmenopausal women.

ORGANISM(S): Homo sapiens

PROVIDER: GSE114372 | GEO | 2019/05/11

REPOSITORIES: GEO

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Project description:Background: Obesity is a risk factor for breast cancer in postmenopausal women and is associated with decreased survival and less favorable clinical characteristics such as greater tumor burden, higher grade, and poor prognosis, regardless of menopausal status. Despite the negative impact of obesity on clinical outcome, molecular mechanisms through which excess adiposity influences breast cancer etiology are not well-defined. Methods: Affymetrix U133 2.0 gene expression data were generated for 405 primary breast tumors using RNA isolated from laser microdissected tissues. Patients were classified as normal-weight (BMI<25), overweight (BMI 25-29.9) or obese (BMI>30). Statistical analysis was performed by ANOVA using Partek Genomics Suite version 6.6 using a false discovery rate <0.05 to define significance. Results: Obese patients were significantly more likely to be diagnosed >50 years or with African American ancestry compared to lean or overweight women. Pathological characteristics, including tumor stage, size or grade, lymph node status, intrinsic subtype, and breast cancer mortality did not differ significantly between groups. No significant gene expression differences were detected by BMI In a non-stratified analysis which included all subtypes or within luminal B, HER2-enriched or basal-like subtypes. Within luminal A tumors, however, 84 probes representing 77 genes from pathways such as cell cycle, p53 and mTOR signaling, tight junctions and a number of cancer associated pathways were differentially expressed. Conclusions: Identification of transcriptome differences in luminal A tumors from normal-weight compared to obese women suggests that obesity alters gene expression within ER+ tumor epithelial cells. Alterations of pathways involved in cell cycle control, tumorigenesis and metabolism may promote cellular proliferation and provide a molecular explanation for less favorable outcome of obese women with breast cancer. Targeted treatments, such as mTOR inhibitors, may allow for improved treatment and survival of obese women, especially African American women, who are more likely to be obese and suffer outcome disparities.

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Estrogen receptor and mTOR signaling rewires cancer metabolism in obesity-associated breast cancer

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