De-regulated estrogen receptor (ER) function is a key feature of approximately 70% of breast cancers. Given that the tumourigenic properties of ER primarily lie in its function as a growth-controlling transcription factor, we sought to discover novel modulators of ER transcriptional activity. Using an RNAi loss-of-function screen, we identified the deubiquitinating enzyme USP11 as a key regulator of ER transcriptional activity. Aims: We hypothesize that USP11 influences ER activation through removal of ubiquitin moieties that block acetylation and repress ER transcriptional activity.
We propose to:
1) Determine the role of USP11 de-ubiquitinating activity in controlling ER function and the effect modulating USP11 has on the ubiquitination/acetylation balance of ER.
2) Determine the effect of USP11 on the response of ER+ breast cancer cells to anti-endocrine therapy and examine the effect of CRISPR knock-in ER mutations on the ability of USP11 to control ER function.
3) Further validate USP11 as a breast cancer biomarker and evaluate the in vivo effect of USP11 modulation on the growth of ER+ breast cancers and their response to anti-endocrine therapy.
Techniques and Methodology:
A combination of immuno-precipitation, mass spectrometry and RNAi will be used to map target lysines and explore the functional relevance of their modification. Impact on response to anti-endocrine drugs will be evaluated using in vitro growth assays and xenografts in nude mice and the impact of ER mutations on these responses assessed. Tissue microarrays will be used to evaluate the
clinical relevance of USP11.
Impact on breast cancer research ER remains a rational therapeutic target in both the primary and recurrent setting and the discovery of novel mechanisms controlling ER function offer attractive new therapeutic opportunities.
The Molecular Oncology Laboratory at the Dept. of Molecular & Cellular Therapeutics, led by Dr Darran O’Connor (http://www.rcsi.ie/index.jsp?p=256&n=726&a=6338
), is a young, vibrant and wellfunded research group focused on the identification and mechanistic anchoring of novel cancer biomarkers and therapeutic targets. As part of major national and international research consortia (e.g Breast-Predict Cancer Centre (www.breastpredict.com), RATHER (www.ratherproject.com) and Angiopredict
(www.angiopredict.com)) the lab has a network of world-class collaborators in the cancer research field, with ample opportunity for national and international secondment.
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