Non-invasive imaging of estrogen receptor-coregulator interaction by luciferase fragment complementation
Author(s)
Lake, Madryn
Type
Thesis
Abstract
Breast cancer is the most common cancer in the UK and approximately 1 in 8 women
will be affected by the disease. Estrogen regulates breast cancer growth through the
action of the estrogen receptors ERα and ERβ. Antiestrogens, in particular tamoxifen,
have contributed greatly to the reduction in breast cancer mortality. Tamoxifen is a
tissue selective antiestrogen; it is antiestrogenic in the breast but estrogenic in other
tissues, thereby enabling it to promote the beneficial effects of estrogen, such as
maintaining bone density. However, like estrogen, tamoxifen also promotes
endometrial cancer, so there is an impetus for the development of novel tissue
selective ERα ligands.
Regulation of gene expression by the estrogen receptors requires the ligand-regulated
recruitment of transcription coregulator proteins. In breast cancer ERα-coactivator
interactions are associated with tumour progression while ERα-corepressor
interactions are associated with receptor antagonism and a therapeutic block of ERα
signalling.
This thesis details the development of a luciferase fragment complementation assay to
image the interaction of ERα with the coactivator AIB1 and corepressor SMRT. It is
hoped that elucidation of these interactions will enable a greater appreciation of the
tissue selective actions of ERα ligands and aid in the screening of novel ERα
antagonists.
By means of complimentary luciferase fragment fusion proteins, it is shown that
ligand dependent ERα-coregulator interaction can be imaged in vitro and in vivo.
ERα and AIB1 luciferase fusion proteins indicate an E2 induced increase in luciferase
fragment complementation which is modulated by antiestrogens. The
complementation observed correlates with ERα transcriptional activity and the
specificity has been further validated by ERα fusion protein mutants. Consistent with
the notion that the ERα-SMRT interaction is characteristic of ERα antagonism, ERα
and SMRT fusion proteins show increased luciferase fragment complementation with
antiestrogens compared with estrogen.
will be affected by the disease. Estrogen regulates breast cancer growth through the
action of the estrogen receptors ERα and ERβ. Antiestrogens, in particular tamoxifen,
have contributed greatly to the reduction in breast cancer mortality. Tamoxifen is a
tissue selective antiestrogen; it is antiestrogenic in the breast but estrogenic in other
tissues, thereby enabling it to promote the beneficial effects of estrogen, such as
maintaining bone density. However, like estrogen, tamoxifen also promotes
endometrial cancer, so there is an impetus for the development of novel tissue
selective ERα ligands.
Regulation of gene expression by the estrogen receptors requires the ligand-regulated
recruitment of transcription coregulator proteins. In breast cancer ERα-coactivator
interactions are associated with tumour progression while ERα-corepressor
interactions are associated with receptor antagonism and a therapeutic block of ERα
signalling.
This thesis details the development of a luciferase fragment complementation assay to
image the interaction of ERα with the coactivator AIB1 and corepressor SMRT. It is
hoped that elucidation of these interactions will enable a greater appreciation of the
tissue selective actions of ERα ligands and aid in the screening of novel ERα
antagonists.
By means of complimentary luciferase fragment fusion proteins, it is shown that
ligand dependent ERα-coregulator interaction can be imaged in vitro and in vivo.
ERα and AIB1 luciferase fusion proteins indicate an E2 induced increase in luciferase
fragment complementation which is modulated by antiestrogens. The
complementation observed correlates with ERα transcriptional activity and the
specificity has been further validated by ERα fusion protein mutants. Consistent with
the notion that the ERα-SMRT interaction is characteristic of ERα antagonism, ERα
and SMRT fusion proteins show increased luciferase fragment complementation with
antiestrogens compared with estrogen.
Date Issued
2012
Date Awarded
2012-02
Copyright Statement
Attribution NoDerivatives 4.0 International Licence (CC BY-ND)
Advisor
Nguyen, Quang-De
Ali, Simak
Aboagye, Eric
Publisher Department
Medicine: Department of Surgery and Cancer
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)