TY - JOUR
T1 - Estrogen protects against obesity-induced mammary gland inflammation in mice
AU - Bhardwaj, Priya
AU - Du, Baoheng
AU - Zhou, Kathy Xi
AU - Sue, Erika
AU - Giri, Dilip
AU - Harbus, Michael D.
AU - Falcone, Domenick J.
AU - Hudis, Clifford A.
AU - Subbaramaiah, Kotha
AU - Dannenberg, Andrew J.
N1 - Publisher Copyright:
©2015 AACR.
PY - 2015/8/1
Y1 - 2015/8/1
N2 - Obesity is a risk factor for the development of hormone receptor (HR)-positive breast cancer in postmenopausal women. Obesity causes subclinical inflammation in white adipose tissue (WAT), characterized by macrophages surrounding dead or dying adipocytes forming crown-like structures (CLS). Estrogen synthesis is catalyzed by aromatase. Previously, we demonstrated CLS and elevated levels of proinflammatory mediators and aromatase in the mammary glands of obese mice and breast tissue of obese women. Here, we tested the hypothesis that supplemental estrogen could prevent or reverse WAT inflammation (WATi) and related molecular changes in the mammary gland. C57BL/6J mice were ovariectomized (OVX) to simulate the postmenopausal state. Supplementation with 17β-estradiol (E2) protected against high fat diet (HFD)-induced weight gain and mammary glands WATi. Expression of proinflammatory mediators (Cox-2, TNFα, IL1β) and aromatase were also reduced in the mammary glands of mice that received supplemental E2. Next, to determine whether E2 supplementation can reverse WATi, obese OVX mice were treated with E2 or placebo and then continued on HFD. E2 supplementation induced weight loss, reversed mammary gland inflammation, and downregulated expression of proinflammatory mediators and aromatase. Finally, we determined whether the protective effects of E2 were mediated by estrogen receptor-α (ERα). Knocking out ERα in ovary intact mice fed a HFD led to weight gain, WATi and elevated levels of proinflammatory mediators and aromatase mimicking the effects of OVX. Taken together, our findings indicate that estrogen via ERα protects against weight gain, WATi and associated increases in proinflammatory mediators and aromatase in the mammary gland.
AB - Obesity is a risk factor for the development of hormone receptor (HR)-positive breast cancer in postmenopausal women. Obesity causes subclinical inflammation in white adipose tissue (WAT), characterized by macrophages surrounding dead or dying adipocytes forming crown-like structures (CLS). Estrogen synthesis is catalyzed by aromatase. Previously, we demonstrated CLS and elevated levels of proinflammatory mediators and aromatase in the mammary glands of obese mice and breast tissue of obese women. Here, we tested the hypothesis that supplemental estrogen could prevent or reverse WAT inflammation (WATi) and related molecular changes in the mammary gland. C57BL/6J mice were ovariectomized (OVX) to simulate the postmenopausal state. Supplementation with 17β-estradiol (E2) protected against high fat diet (HFD)-induced weight gain and mammary glands WATi. Expression of proinflammatory mediators (Cox-2, TNFα, IL1β) and aromatase were also reduced in the mammary glands of mice that received supplemental E2. Next, to determine whether E2 supplementation can reverse WATi, obese OVX mice were treated with E2 or placebo and then continued on HFD. E2 supplementation induced weight loss, reversed mammary gland inflammation, and downregulated expression of proinflammatory mediators and aromatase. Finally, we determined whether the protective effects of E2 were mediated by estrogen receptor-α (ERα). Knocking out ERα in ovary intact mice fed a HFD led to weight gain, WATi and elevated levels of proinflammatory mediators and aromatase mimicking the effects of OVX. Taken together, our findings indicate that estrogen via ERα protects against weight gain, WATi and associated increases in proinflammatory mediators and aromatase in the mammary gland.
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U2 - 10.1158/1940-6207.CAPR-15-0082
DO - 10.1158/1940-6207.CAPR-15-0082
M3 - Article
C2 - 26038116
AN - SCOPUS:84942017434
SN - 1940-6207
VL - 8
SP - 751
EP - 759
JO - Cancer Prevention Research
JF - Cancer Prevention Research
IS - 8
ER -