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Age and estrogen-dependent inflammation in breast adenocarcinoma and normal breast tissue [cohort_2]

ABSTRACT: Chronic inflammation promotes breast tumor growth and invasion by accelerating angiogenesis and tissue remodeling in the tumor microenvironment. The relationship between inflammation and estrogen, which drives the growth of 70 percent of breast tumors, is complex. Low levels of estrogen exposure stimulate macrophages and other inflammatory cell populations, but very high levels are immune suppressive. Breast tumor incidence is increased by obesity and age, which interact to influence inflammatory cell populations in normal breast tissue. The molecular impact of these factors on tumor initiation and growth is not well-understood. We modeled the difference in gene expression between 195 breast adenocarcinomas and 195 matched adjacent normal breast tissue samples, using age, body mass index (BMI), and tumor subtype as covariates. Age and BMI were independently associated with inflammation in normal tissue but not tumors. Older patients with ER-positive disease had tumors with higher levels of Estrogen Receptor (ER) signaling compared to adjacent normal tissue and had lower relative levels of tumor macrophage expression. We developed a novel statistic to quantify the rewiring of gene co-expression networks and demonstrate that in ER-positive tumors basal gene networks are rewired even though their expression levels of these genes are not significantly different from those in adjacent normal tissue. Patient age influences the molecular profile of ER-positive breast tumors. Our data support an immunosuppressive effect of estrogen signaling in the breast tumor microenvironment, suggesting this effect contributes to the greater presence of prognostic and therapeutically relevant immune cells in ER-negative tumors.

ORGANISM(S): Homo sapiens

PROVIDER: GSE70947 | GEO | 2016/07/01

SECONDARY ACCESSION(S): PRJNA290007

REPOSITORIES: GEO

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Project description:Limited knowledge of the changes in estrogen receptor (ER) signaling during the transformation of the normal mammary gland to breast cancer hinders the development of effective prevention and treatment strategies. Differences in estrogen signaling between normal human primary breast epithelial cells and primary breast tumors obtained immediately following surgical excision were explored. Transcriptional profiling of normal ER+ mature luminal mammary epithelial cells and ER+ breast tumors revealed significant difference in the response to estrogen stimulation. Consistent with these differences in gene expression, the normal and tumor ER cistromes were distinct and sufficient to segregate normal breast tissues from breast tumors. The selective enrichment of the DNA binding motif GRHL2 in the breast cancer-specific ER cistrome suggests that it may play a role in the differential function of ER in breast cancer. Depletion of GRHL2 resulted in altered ER binding and differential transcriptional responses to estrogen stimulation. Furthermore, GRHL2 was demonstrated to be essential for estrogen-stimulated proliferation of ER+ breast cancer cells. DLC1 was also identified as an estrogen-induced tumor suppressor in the normal mammary gland with decreased expression in breast cancer. In clinical cohorts, loss of DLC1 and gain of GRHL2 expression are associated with breast cancer and are independently predictive for worse survival. This study suggests that normal ER signaling is lost and tumor-specific ER signaling is gained during breast tumorigenesis. Unraveling these changes in ER signaling during breast cancer progression should aid the development of more effective prevention strategies and targeted therapeutics. SIGNIFICANCE STATEMENT: Abnormal estrogen receptor (ER) signaling drives the majority of breast cancers and is targeted by endocrine therapies. However, in normal breast tissue, ER signaling has been demonstrated to promote benign functions such as development and differentiation. Using genomic techniques to characterize ER function in normal breast and breast tumors, this study reveals differential patterns of ER signaling, suggesting that normal ER signaling is lost and tumorigenic ER signaling gained during breast tumor formation. Better understanding of this process can aid the development of improved breast cancer prevention strategies and therapies.

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Age and estrogen-dependent inflammation in breast adenocarcinoma and normal breast tissue [cohort_2]

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