title: Glucocorticoid-induced impairment of mammary gland involution is associated with STAT5 and STAT3 signaling modulation.
abstract: The mammary epithelium undergoes cyclical periods of cellular proliferation, differentiation, and regression. During lactation, the signal transducer and activator of transcription factor (STAT)-5A and the glucocorticoid receptor (GR) synergize to induce milk protein expression and also act as survival factors. During involution, STAT3 activation mediates epithelial cell apoptosis and mammary gland remodeling. It has been shown that the administration of glucocorticoids at weaning prevents epithelial cell death, probably by extracellular matrix breakdown prevention. Our results show that the synthetic glucocorticoid dexamethasone (DEX) modulates STAT5A and STAT3 signaling and inhibits apoptosis induction in postlactating mouse mammary glands, only when administered within the first 48 h upon cessation of suckling. DEX administration right after weaning delayed STAT5A inactivation and degradation, preserving gene expression of target genes as β-casein (bcas) and prolactin induced protein (pip). Weaning-triggered GR down-regulation is also delayed by the hormone treatment. Moreover, DEX administration delayed STAT3 activation and translocation into epithelial cells nuclei. In particular, DEX treatment impaired the increment in gene expression of signal transducer subunit gp130, normally up-regulated from lactation to involution and responsible for STAT3 activation. Therefore, the data shown herein indicate that glucocorticoids are able to modulate early involution by controlling the strong cross talk that GR, STAT5, and STAT3 pathways maintains in the mammary epithelium.
authors.affiliation: Instituto de Fisiología Biología y Neurociencias-Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina.
authors.forename: Paola Y
authors.initials: PY
authors.lastname: Bertucci
authors.forename: Ana
authors.initials: A
authors.lastname: Quaglino
authors.forename: Andrea G
authors.initials: AG
authors.lastname: Pozzi
authors.forename: Edith C
authors.initials: EC
authors.lastname: Kordon
authors.forename: Adali
authors.initials: A
authors.lastname: Pecci
mesh_terms: D000818:Animals; D050822:Cytokine Receptor gp130 / Q000235:genetics / Q000378:metabolism; D053938:DNA Fragmentation; D003907:Dexamethasone / Q000008:administration & dosage / Q000494:pharmacology*; D005260:Female; D005786:Gene Expression Regulation / Q000502:physiology; D005938:Glucocorticoids / Q000008:administration & dosage / Q000494:pharmacology; D007774:Lactation / Q000502:physiology; D053605:Leukemia Inhibitory Factor / Q000235:genetics / Q000378:metabolism; D008321:Mammary Glands, Animal / Q000187:drug effects / Q000502:physiology*; D051379:Mice; D008807:Mice, Inbred BALB C; D050796:STAT3 Transcription Factor / Q000235:genetics / Q000378:metabolism*; D050799:STAT5 Transcription Factor / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*
chemical_list: D005938:Glucocorticoids; C494200:Il6st protein, mouse; D053605:Leukemia Inhibitory Factor; C507838:Lif protein, mouse; D050796:STAT3 Transcription Factor; D050799:STAT5 Transcription Factor; C494087:Stat3 protein, mouse; C494093:Stat5a protein, mouse; D050822:Cytokine Receptor gp130; D003907:Dexamethasone