Estradiol Affects Extracellular Leptin: Adiponectin Ratio in Human Breast Tissue in Vivo

• Context: Exposure to sex steroids is associated with increased breast cancer risk, and adipokines, leptin and adiponectin have been implicated in cancer progression. However, it is not known whether sex steroids affect adipokine secretion in breast tissue. Objective: To elucidate the role of estrogen and tamoxifen on adipokine release in normal human breast tissue and breast cancer. Setting and Design: Microdialysis sampling was used to collect extracellular in vivo leptin and adiponectin from normal human breast tissue in premenopausal healthy volunteers during the menstrual cycle and in postmenopausal women before tamoxifen treatment and after 6 weeks of treatment. In women with breast cancer, microdialysis was performed intratumorally before surgery. In addition, whole normal breast tissue biopsies were cultured ex vivo, and murine breast cancer models were evaluated. Results: In normal breast tissue, plasma estradiol negatively correlated with local extracellular adiponectin levels (r = -0.34; P less than .05) and positively correlated with leptin (r = 0.37; P less than .05) and leptin: adiponectin ratio (r = 0.38; P less than .05). In postmenopausal women, tamoxifen treatment increased adiponectin (P less than 0.05) and decreased leptin (P less than .01) and the leptin: adiponectin ratio (P less than .01). These in vivo results were confirmed in breast tissue biopsies cultured ex vivo. In patients with breast cancer, extracellular leptin was higher (P less than .01) and adiponectin lower (P less than .05) in tumors than in normal adjacent breast tissue. In a murine model of breast cancer, estrogen exposure increased leptin secretion (P less than .05). Conclusions: Estrogen exposure may have a critical role in the regulation of adipokines in human breast tissue and may serve as therapeutic targets for treatment and prevention.

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MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine (hsv//eng)

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