Signaling and antiproliferative effects mediated by GnRH receptors after expression in breast cancer cells using recombinant adenovirus

H M Everest, J N Hislop, T Harding, J B Uney, A Flynn, R P Millar, C A McArdle

Research output: Contribution to journalArticle

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Abstract

GnRH receptors (GnRH-Rs) are found in human cancers, including those of the breast, and GnRH can inhibit the growth of cell lines derived from such cancers. Although pituitary and extrapituitary GnRH-R transcripts appear identical, their functional characteristics may differ. Most extrapituitary GnRH-Rs have low affinity for GnRH analogs and may not activate PLC or discriminate between agonists and antagonists in the same way as pituitary GnRH-Rs. Here we have assessed whether GnRH-Rs expressed exogenously in breast cancer cells differ from those in gonadotropes. We found no evidence for endogenous GnRH-Rs in MCF7 cells, but after infection with adenovirus expressing the GnRH-R (Ad GnRH-R) at a multiplicity of infection of 10 or greater, at least 80% expressed GnRH-Rs. These had high affinity (K(d) for [(125)I]buserelin, 1.4 nM) and specificity (rank order of potency, buserelin>GnRH>chicken GnRH-II) and mediated stimulation of [(3)H]IP accumulation. Increasing viral titer [from multiplicity of infection, 3-300] increased receptor number (10,000-225,000 sites/cell) and [(3)H]IP responses. GnRH stimulated ERK2 phosphorylation in Ad GnRH-R-infected cells, and this effect, like stimulation of [(3)H]IP accumulation, was blocked by GnRH-R antagonists. GnRH also inhibited [(3)H]thymidine incorporation into Ad GnRH-R-infected cells (but not control cells). This effect was mimicked by agonist analogs and inhibited by two antagonists. Thus, when exogenous GnRH-Rs are expressed at density comparable to that in gonadotropes, they are functionally indistinguishable from the endogenous GnRH-Rs in gonadotropes, and increasing expression of high affinity GnRH-Rs can dramatically enhance the direct antiproliferative effect of GnRH agonists on breast cancer cells.
Original languageEnglish
Pages (from-to)4663-72
Number of pages10
JournalEndocrinology
Volume142
Issue number11
DOIs
Publication statusPublished - Nov 2001

Fingerprint

LHRH Receptors
Adenoviridae
Gonadotropin-Releasing Hormone
Breast Neoplasms
Buserelin
Adenoviridae Infections
MCF-7 Cells
Infection
Thymidine

Keywords

  • Adenoviridae
  • Binding, Competitive
  • Breast Neoplasms
  • Cell Division
  • Female
  • Gene Transfer Techniques
  • Gonadotropin-Releasing Hormone
  • Humans
  • Inositol Phosphates
  • Mitogen-Activated Protein Kinase 1
  • Phosphorylation
  • Receptors, LHRH
  • Recombination, Genetic
  • Signal Transduction
  • Thymidine
  • Tumor Cells, Cultured

Cite this

Signaling and antiproliferative effects mediated by GnRH receptors after expression in breast cancer cells using recombinant adenovirus. / Everest, H M; Hislop, J N; Harding, T; Uney, J B; Flynn, A; Millar, R P; McArdle, C A.

In: Endocrinology, Vol. 142, No. 11, 11.2001, p. 4663-72.

Research output: Contribution to journalArticle

Everest, H M ; Hislop, J N ; Harding, T ; Uney, J B ; Flynn, A ; Millar, R P ; McArdle, C A. / Signaling and antiproliferative effects mediated by GnRH receptors after expression in breast cancer cells using recombinant adenovirus. In: Endocrinology. 2001 ; Vol. 142, No. 11. pp. 4663-72.
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abstract = "GnRH receptors (GnRH-Rs) are found in human cancers, including those of the breast, and GnRH can inhibit the growth of cell lines derived from such cancers. Although pituitary and extrapituitary GnRH-R transcripts appear identical, their functional characteristics may differ. Most extrapituitary GnRH-Rs have low affinity for GnRH analogs and may not activate PLC or discriminate between agonists and antagonists in the same way as pituitary GnRH-Rs. Here we have assessed whether GnRH-Rs expressed exogenously in breast cancer cells differ from those in gonadotropes. We found no evidence for endogenous GnRH-Rs in MCF7 cells, but after infection with adenovirus expressing the GnRH-R (Ad GnRH-R) at a multiplicity of infection of 10 or greater, at least 80{\%} expressed GnRH-Rs. These had high affinity (K(d) for [(125)I]buserelin, 1.4 nM) and specificity (rank order of potency, buserelin>GnRH>chicken GnRH-II) and mediated stimulation of [(3)H]IP accumulation. Increasing viral titer [from multiplicity of infection, 3-300] increased receptor number (10,000-225,000 sites/cell) and [(3)H]IP responses. GnRH stimulated ERK2 phosphorylation in Ad GnRH-R-infected cells, and this effect, like stimulation of [(3)H]IP accumulation, was blocked by GnRH-R antagonists. GnRH also inhibited [(3)H]thymidine incorporation into Ad GnRH-R-infected cells (but not control cells). This effect was mimicked by agonist analogs and inhibited by two antagonists. Thus, when exogenous GnRH-Rs are expressed at density comparable to that in gonadotropes, they are functionally indistinguishable from the endogenous GnRH-Rs in gonadotropes, and increasing expression of high affinity GnRH-Rs can dramatically enhance the direct antiproliferative effect of GnRH agonists on breast cancer cells.",
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AU - Hislop, J N

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AU - Uney, J B

AU - Flynn, A

AU - Millar, R P

AU - McArdle, C A

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N2 - GnRH receptors (GnRH-Rs) are found in human cancers, including those of the breast, and GnRH can inhibit the growth of cell lines derived from such cancers. Although pituitary and extrapituitary GnRH-R transcripts appear identical, their functional characteristics may differ. Most extrapituitary GnRH-Rs have low affinity for GnRH analogs and may not activate PLC or discriminate between agonists and antagonists in the same way as pituitary GnRH-Rs. Here we have assessed whether GnRH-Rs expressed exogenously in breast cancer cells differ from those in gonadotropes. We found no evidence for endogenous GnRH-Rs in MCF7 cells, but after infection with adenovirus expressing the GnRH-R (Ad GnRH-R) at a multiplicity of infection of 10 or greater, at least 80% expressed GnRH-Rs. These had high affinity (K(d) for [(125)I]buserelin, 1.4 nM) and specificity (rank order of potency, buserelin>GnRH>chicken GnRH-II) and mediated stimulation of [(3)H]IP accumulation. Increasing viral titer [from multiplicity of infection, 3-300] increased receptor number (10,000-225,000 sites/cell) and [(3)H]IP responses. GnRH stimulated ERK2 phosphorylation in Ad GnRH-R-infected cells, and this effect, like stimulation of [(3)H]IP accumulation, was blocked by GnRH-R antagonists. GnRH also inhibited [(3)H]thymidine incorporation into Ad GnRH-R-infected cells (but not control cells). This effect was mimicked by agonist analogs and inhibited by two antagonists. Thus, when exogenous GnRH-Rs are expressed at density comparable to that in gonadotropes, they are functionally indistinguishable from the endogenous GnRH-Rs in gonadotropes, and increasing expression of high affinity GnRH-Rs can dramatically enhance the direct antiproliferative effect of GnRH agonists on breast cancer cells.

AB - GnRH receptors (GnRH-Rs) are found in human cancers, including those of the breast, and GnRH can inhibit the growth of cell lines derived from such cancers. Although pituitary and extrapituitary GnRH-R transcripts appear identical, their functional characteristics may differ. Most extrapituitary GnRH-Rs have low affinity for GnRH analogs and may not activate PLC or discriminate between agonists and antagonists in the same way as pituitary GnRH-Rs. Here we have assessed whether GnRH-Rs expressed exogenously in breast cancer cells differ from those in gonadotropes. We found no evidence for endogenous GnRH-Rs in MCF7 cells, but after infection with adenovirus expressing the GnRH-R (Ad GnRH-R) at a multiplicity of infection of 10 or greater, at least 80% expressed GnRH-Rs. These had high affinity (K(d) for [(125)I]buserelin, 1.4 nM) and specificity (rank order of potency, buserelin>GnRH>chicken GnRH-II) and mediated stimulation of [(3)H]IP accumulation. Increasing viral titer [from multiplicity of infection, 3-300] increased receptor number (10,000-225,000 sites/cell) and [(3)H]IP responses. GnRH stimulated ERK2 phosphorylation in Ad GnRH-R-infected cells, and this effect, like stimulation of [(3)H]IP accumulation, was blocked by GnRH-R antagonists. GnRH also inhibited [(3)H]thymidine incorporation into Ad GnRH-R-infected cells (but not control cells). This effect was mimicked by agonist analogs and inhibited by two antagonists. Thus, when exogenous GnRH-Rs are expressed at density comparable to that in gonadotropes, they are functionally indistinguishable from the endogenous GnRH-Rs in gonadotropes, and increasing expression of high affinity GnRH-Rs can dramatically enhance the direct antiproliferative effect of GnRH agonists on breast cancer cells.

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KW - Cell Division

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KW - Gene Transfer Techniques

KW - Gonadotropin-Releasing Hormone

KW - Humans

KW - Inositol Phosphates

KW - Mitogen-Activated Protein Kinase 1

KW - Phosphorylation

KW - Receptors, LHRH

KW - Recombination, Genetic

KW - Signal Transduction

KW - Thymidine

KW - Tumor Cells, Cultured

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DO - 10.1210/endo.142.11.8503

M3 - Article

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JO - Endocrinology

JF - Endocrinology

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