The Major Pre- and Postmenopausal Estrogens Play Opposing Roles in Obesity-Driven Mammary Inflammation and Breast Cancer Development.

Many inflammation-associated diseases, including cancers, increase in women after menopause and with obesity. In contrast to anti-inflammatory actions of 17ß-estradiol, we find estrone, which dominates after menopause, is pro-inflammatory. In human mammary adipocytes, cytokine expression increases with obesity, menopause, and cancer. Adipocyte:cancer cell interaction stimulates estrone- and NFκB-dependent pro-inflammatory cytokine upregulation. Estrone- and 17ß-estradiol-driven transcriptomes differ. Estrone:ERα stimulates NFκB-mediated cytokine gene induction; 17ß-estradiol opposes this. In obese mice, estrone increases and 17ß-estradiol relieves inflammation. Estrone drives more rapid ER+ breast cancer growth in vivo. HSD17B14, which converts 17ß-estradiol to estrone, associates with poor ER+ breast cancer outcome. Estrone and HSD17B14 upregulate inflammation, ALDH1 activity, and tumorspheres, while 17ß-estradiol and HSD17B14 knockdown oppose these. Finally, a high intratumor estrone:17ß-estradiol ratio increases tumor-initiating stem cells and ER+ cancer growth in vivo. These findings help explain why postmenopausal ER+ breast cancer increases with obesity, and offer new strategies for prevention and therapy.

Respuesta hormonal de las células madre de mama y resistencia a tamoxifeno / Hormone response of breast stem cells and tamoxifen resistance

Objetivo. Determinar la influencia a nivel celular y molecular de varios tratamientos hormonales (estrógeno, tamoxifeno y fulvestrant) sobre las células epiteliales y las células madre de la mama sana y tumoral. Métodos. Se emplearon muestras de tejido mamario sano y tumoral, así como líneas celulares de cáncer de mama y células resistentes a tamoxifeno, para analizar los efectos de las hormonas sobre la proliferación y diferenciación celular. Resultados. Las células epiteliales y las células madre de la mama respondieron de forma diferente a los tratamientos hormonales. Las células resistentes a tamoxifeno presentaban un mayor contenido de células madre cancerosas y expresaban niveles de Sox2 más elevados, mientras que los niveles de expresión del receptor de progesterona eran muy bajos. Las células resistentes a tamoxifeno eran, además, más resistentes al tratamiento con fulvestrant. Conclusiones. El desarrollo de resistencia a tamoxifeno está asociado con un incremento en el contenido de células madre cancerosas. El tratamiento con fulvestrant no parece disminuir la población de células madre cancerosas. Sox2 podría ser un biomarcador de resistencia a tamoxifeno en el cáncer de mama (AU)

Objective. To determine the influence of various hormones (estrogen, tamoxifen and fulvestrant) on cell proliferation and differentiation in normal and cancer breast stem cells. Methods. Primary tissue samples, breast cancer cell lines and tamoxifen-resistant cells were used to analyze the effects of hormones on cell proliferation and differentiation. Results. Breast epithelial cells and stem cells responded differentially to hormone treatments. Tamoxifen-resistant cells showed increased cancer stem cell content and expressed higher Sox2 levels, while progesterone receptor levels were very low. Tamoxifen-resistant cells were resistant to fulvestrant treatment. Conclusions. The development of tamoxifen resistance is associated with an increase in cancer stem cell content. Treatment with fulvestrant does not appear to reduce the cancer stem cell population. Sox2 could represent a biomarker of tamoxifen resistance in breast cancer (AU)