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Prolactin inhibits cell loss and decreases matrix metalloproteinase expression in the involuting mouse mammary gland but fails to prevent cell loss in the mammary glands of mice expressing IGFBP-5 as a mammary transgene

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Original languageEnglish
Pages (from-to)435-48
Number of pages14
JournalJournal of molecular endocrinology
Issue number3
Publication statusPublished - Jun 2006


Insulin-like growth factor-binding protein 5 (IGFBP-5) mediates involution of the mammary gland. The decrease in DNA content and mammary gland weight which accompanies involution was inhibited by prolactin (PRL) in wild-type but not transgenic mice expressing IGFBP-5. Phospho-STAT5 protein levels were significantly lower in IGFBP-5 transgenic mice during lactation suggesting that IGFBP-5 antagonises PRL signalling in the mammary epithelium. In contrast, phospho-STAT3 levels increased during involution to a similar extent in both wild-type and transgenic mice and were unaffected by PRL. PRL inhibited gene expression of matrix metalloproteinases (MMPs) 3 and 12 but not tissue plasminogen activator or plasmin in wild-type and transgenic animals. The effects of PRL on MMPs appear to be indirect since PRL failed to inhibit MMP-3, -7 or -12 expression in HC-11 cells or in a co-transfection including an activated PRL receptor, STAT5 and a MMP-3-luciferase reporter gene. PRL is a potent inhibitor, both of cell death, an effect which is suppressed by IGFBP-5, and of MMP expression, which is independent of the actions of IGFBP-5.

    Research areas

  • Animals, Caseins, Cell Line, Cricetinae, Female, Fibrinolysin, Gene Expression Regulation, Enzymologic, Genes, Reporter, Insulin-Like Growth Factor Binding Protein 5, Lactation, Mammary Glands, Animal, Matrix Metalloproteinases, Mice, Mice, Inbred C57BL, Mice, Inbred CBA, Mice, Transgenic, Prolactin, Proto-Oncogene Proteins c-akt, Rats, Receptors, Somatomedin, STAT3 Transcription Factor, STAT5 Transcription Factor, Signal Transduction, Somatomedins, Tissue Plasminogen Activator, Transgenes

ID: 8778420