Insulin-like growth factor binding protein-5 (IGFBP-5) induces premature cell death in the mammary glands of transgenic mice

Elizabeth Tonner, Michael C. Barber, Gordon J. Allan, James Beattie, John Webster, C. Bruce Whitelaw, David J. Flint

Research output: Contribution to journalArticle

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Abstract

We have previously demonstrated that IGFBP-5 production by mammary epithelial cells increases dramatically during involution of the mammary gland. To demonstrate a causal relationship between IGFBP-5 and cell death we created transgenic mice expressing IGFBP-5 in the mammary gland using a mammary-specific promoter, ß-lactoglobulin. DNA content in the mammary glands of transgenic mice was decreased as early as day 10 of pregnancy. Histological analysis indicated reduced numbers of alveolar end buds, with decreased ductal branching. Transgenic dams produced IGFBP-5 in their milk at concentrations similar to those achieved at the end of normal lactation. Mammary cell number and milk synthesis were both decreased by approximately 50% during the first 10 days of lactation. BrdU labelling was decreased, whereas DNA ladders were increased in transgenic animals on day 1 of lactation. On day 2 postpartum, the epithelial invasion of the mammary fat pad was clearly impaired in transgenic animals. The concentrations of the pro-apoptotic molecule caspase-3 and of plasmin were both increased in transgenic animals whilst the concentrations of 2 prosurvival molecules Bcl-2 and Bcl-xLwere both decreased. In order to examine whether IGFBP-5 acts by inhibiting the survival effect of IGF-I we examined IGF receptor phosphorylation and Akt phosphorylation and showed that both were inhibited. We attempted to "rescue" the transgenic phenotype by using growth hormone to increase endogenous IGF-I concentrations or by implanting minipumps delivering an IGF-1 analogue, R3-IGF-1, which binds weakly to IGFBP-5. Growth hormone treatment failed to affect mammary development suggesting that increased concentrations of endogenous IGF-1 are insufficient to overcome the high concentrations of IGFBP-5 produced by these transgenic animals. In contrast mammary development (gland weight and DNA content) was normalised by R3-IGF-I although milk production was only partially restored. This is the first demonstration that over-expression of IGFBP-5 can lead to; impaired mammary development, increased expression of the pro-apoptotic molecule caspase-3, increased plasmin generation and decreased expression of pro-survival molecules of the Bcl-2 family. It clearly demonstrates that IGF-I is an important developmental/survival factor for the mammary gland and, furthermore, this cell death programme may be utilised in a wide variety of tissues.
LanguageEnglish
Pages4547-4557
Number of pages10
JournalDevelopment
Volume129
Publication statusPublished - 2002

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Insulin-Like Growth Factor Binding Protein 5
Premature Mortality
Human Mammary Glands
Transgenic Mice
Insulin-Like Growth Factor I
Cell Death
Genetically Modified Animals
Breast
Lactation
Milk
Fibrinolysin
Caspase 3
Growth Hormone
DNA
Phosphorylation
STAT5 Transcription Factor
Lactoglobulins
Bromodeoxyuridine
Postpartum Period
Adipose Tissue

Keywords

  • IGFBP-5
  • mammary gland
  • involution
  • apoptosis
  • transgenic
  • caspase
  • plasmin
  • Mouse
  • biomedical science

Cite this

Tonner, E., Barber, M. C., Allan, G. J., Beattie, J., Webster, J., Whitelaw, C. B., & Flint, D. J. (2002). Insulin-like growth factor binding protein-5 (IGFBP-5) induces premature cell death in the mammary glands of transgenic mice. Development, 129, 4547-4557.
Tonner, Elizabeth ; Barber, Michael C. ; Allan, Gordon J. ; Beattie, James ; Webster, John ; Whitelaw, C. Bruce ; Flint, David J. / Insulin-like growth factor binding protein-5 (IGFBP-5) induces premature cell death in the mammary glands of transgenic mice. In: Development. 2002 ; Vol. 129. pp. 4547-4557.
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Tonner, E, Barber, MC, Allan, GJ, Beattie, J, Webster, J, Whitelaw, CB & Flint, DJ 2002, 'Insulin-like growth factor binding protein-5 (IGFBP-5) induces premature cell death in the mammary glands of transgenic mice' Development, vol. 129, pp. 4547-4557.

Insulin-like growth factor binding protein-5 (IGFBP-5) induces premature cell death in the mammary glands of transgenic mice. / Tonner, Elizabeth; Barber, Michael C.; Allan, Gordon J.; Beattie, James; Webster, John; Whitelaw, C. Bruce; Flint, David J.

In: Development, Vol. 129, 2002, p. 4547-4557.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Insulin-like growth factor binding protein-5 (IGFBP-5) induces premature cell death in the mammary glands of transgenic mice

AU - Tonner, Elizabeth

AU - Barber, Michael C.

AU - Allan, Gordon J.

AU - Beattie, James

AU - Webster, John

AU - Whitelaw, C. Bruce

AU - Flint, David J.

PY - 2002

Y1 - 2002

N2 - We have previously demonstrated that IGFBP-5 production by mammary epithelial cells increases dramatically during involution of the mammary gland. To demonstrate a causal relationship between IGFBP-5 and cell death we created transgenic mice expressing IGFBP-5 in the mammary gland using a mammary-specific promoter, ß-lactoglobulin. DNA content in the mammary glands of transgenic mice was decreased as early as day 10 of pregnancy. Histological analysis indicated reduced numbers of alveolar end buds, with decreased ductal branching. Transgenic dams produced IGFBP-5 in their milk at concentrations similar to those achieved at the end of normal lactation. Mammary cell number and milk synthesis were both decreased by approximately 50% during the first 10 days of lactation. BrdU labelling was decreased, whereas DNA ladders were increased in transgenic animals on day 1 of lactation. On day 2 postpartum, the epithelial invasion of the mammary fat pad was clearly impaired in transgenic animals. The concentrations of the pro-apoptotic molecule caspase-3 and of plasmin were both increased in transgenic animals whilst the concentrations of 2 prosurvival molecules Bcl-2 and Bcl-xLwere both decreased. In order to examine whether IGFBP-5 acts by inhibiting the survival effect of IGF-I we examined IGF receptor phosphorylation and Akt phosphorylation and showed that both were inhibited. We attempted to "rescue" the transgenic phenotype by using growth hormone to increase endogenous IGF-I concentrations or by implanting minipumps delivering an IGF-1 analogue, R3-IGF-1, which binds weakly to IGFBP-5. Growth hormone treatment failed to affect mammary development suggesting that increased concentrations of endogenous IGF-1 are insufficient to overcome the high concentrations of IGFBP-5 produced by these transgenic animals. In contrast mammary development (gland weight and DNA content) was normalised by R3-IGF-I although milk production was only partially restored. This is the first demonstration that over-expression of IGFBP-5 can lead to; impaired mammary development, increased expression of the pro-apoptotic molecule caspase-3, increased plasmin generation and decreased expression of pro-survival molecules of the Bcl-2 family. It clearly demonstrates that IGF-I is an important developmental/survival factor for the mammary gland and, furthermore, this cell death programme may be utilised in a wide variety of tissues.

AB - We have previously demonstrated that IGFBP-5 production by mammary epithelial cells increases dramatically during involution of the mammary gland. To demonstrate a causal relationship between IGFBP-5 and cell death we created transgenic mice expressing IGFBP-5 in the mammary gland using a mammary-specific promoter, ß-lactoglobulin. DNA content in the mammary glands of transgenic mice was decreased as early as day 10 of pregnancy. Histological analysis indicated reduced numbers of alveolar end buds, with decreased ductal branching. Transgenic dams produced IGFBP-5 in their milk at concentrations similar to those achieved at the end of normal lactation. Mammary cell number and milk synthesis were both decreased by approximately 50% during the first 10 days of lactation. BrdU labelling was decreased, whereas DNA ladders were increased in transgenic animals on day 1 of lactation. On day 2 postpartum, the epithelial invasion of the mammary fat pad was clearly impaired in transgenic animals. The concentrations of the pro-apoptotic molecule caspase-3 and of plasmin were both increased in transgenic animals whilst the concentrations of 2 prosurvival molecules Bcl-2 and Bcl-xLwere both decreased. In order to examine whether IGFBP-5 acts by inhibiting the survival effect of IGF-I we examined IGF receptor phosphorylation and Akt phosphorylation and showed that both were inhibited. We attempted to "rescue" the transgenic phenotype by using growth hormone to increase endogenous IGF-I concentrations or by implanting minipumps delivering an IGF-1 analogue, R3-IGF-1, which binds weakly to IGFBP-5. Growth hormone treatment failed to affect mammary development suggesting that increased concentrations of endogenous IGF-1 are insufficient to overcome the high concentrations of IGFBP-5 produced by these transgenic animals. In contrast mammary development (gland weight and DNA content) was normalised by R3-IGF-I although milk production was only partially restored. This is the first demonstration that over-expression of IGFBP-5 can lead to; impaired mammary development, increased expression of the pro-apoptotic molecule caspase-3, increased plasmin generation and decreased expression of pro-survival molecules of the Bcl-2 family. It clearly demonstrates that IGF-I is an important developmental/survival factor for the mammary gland and, furthermore, this cell death programme may be utilised in a wide variety of tissues.

KW - IGFBP-5

KW - mammary gland

KW - involution

KW - apoptosis

KW - transgenic

KW - caspase

KW - plasmin

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Tonner E, Barber MC, Allan GJ, Beattie J, Webster J, Whitelaw CB et al. Insulin-like growth factor binding protein-5 (IGFBP-5) induces premature cell death in the mammary glands of transgenic mice. Development. 2002;129:4547-4557.