Synergistic interactions between PTEN, HER and Sprouty signalling in prostate cancer

Lead Research Organisation: Beatson Institute for Cancer Research
Department Name: Research Group 8 (Hing Leung)

Abstract

Prostate cancer (PC) is the commonest cancer in men in the UK, with nearly 35,000 new cases a year. The lifetime risk for being diagnosed with PC is 1 in 14.

The reason why and how PC develops and progresses remains poorly understood, and as a result this has hindered the development of effective and safe therapies.

Recent work suggests that signalling pathways (‘information highways‘ within each cell) in the prostate (such as AKT/PTEN, HER2/3 and Sprouty proteins) may be responsible for the development and progression of PC.

I intend to develop a pre-clinical mouse model which will recreate abnormalities in these signalling pathways in an attempt to better understand the molecular mechanisms of PC. I will also analyse resected human PC specimens to evaluate the status of these pathways in a comprehensive manner in order to test if these factors might produce added ‘driving force‘ when present together.

Studying these pathways in a mouse model provides a unique opportunity to try treatment(s) and assess response. Primary and metastatic tumour burden will be assessed using novel imaging techniques (Green Fluorescent Protein tagged to tumour cells) in the live mice. This will provide novel and invaluable data on the treatment responses.

Technical Summary

Aims: Prostate cancer (PC) is the commonest cancer in men in the UK, with nearly 35,000 new cases a year. Our aim is to study the impact of simultaneous activation of the PTEN, HER and Sprouty2 pathways in PC development and progression.

Hypothesis: Multiple events are synergistic in driving human prostate carcinogenesis; these molecular ‘lesions‘ can be developed in a murine transgenic model for in vivo investigation.

Objectives:
1. To perform a comprehensive expression analysis of the above signalling pathways/molecules in clinical PC.
2. To develop transgenic murine model(s) of prostate cancer to study the role of PTEN, HER2 and Sprouty2.
3. To explore the use of in vivo imaging in the above PC model(s).

Design & Methodology: The current mouse models utilise knockout, knock-in or conditional regulation of expression using Cre/lox technology. Using gene targeting, loxP-flanked alleles can be generated to allow deletion of genes as well as (over)expression of transgenes in a prostate (epithelial) specific manner upon expression of Probasin (Pb) Cre. We will analyse different combinations of mice carrying inducible loxP flanked PTEN fl/fl (inducible knockout allele of exon 4/5), neuKI (HER2)(first exon of endogenous neu replaced with cre-inducible activated neu cDNA) and constitutive knockout of Sprouty 2 alleles bred into, Pb(Cre) mice carrying a lox stop lox GFP reporter. Therefore when Cre recombinase is expressed this leads to deletion of PTEN/Sprouty2, and activation of HER2 and GFP expression specifically within the prostate. In the first instance, I will characterise the Pb(Cre):PTEN fl/fl: neuKI phenotypes. In addition, I will also intercross the Pb(Cre): PTEN fl/fl mouse with Sprouty2 since it has also been implicated in prostate carcinogenesis.

To fully characterise the transgenic model(s) I will use histological and immunohistochemistry (IHC) techniques as well as in vitro cell culture and functional assays. The expression of GFP would allow us to regularly assess tumour bulk and metastases with intravital imaging using the OV100 camera. It will also provide the opportunity to assess tumour response to a variety of treatment regimes. I will further consolidate the importance of these signalling pathways using clinical PC tissue microarrays (TMA) to explore the roles of PTEN, HER2 and Sprouty 2.

Medical and Scientific Opportunities: A murine model that reflects the entire continuum of PC would be invaluable for the preclinical evaluation of novel therapy as well as elucidating further the molecular basis of PC.

Publications

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Ahmad I (2012) Mechanisms of FGFR-mediated carcinogenesis. in Biochimica et biophysica acta

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Ahmad I (2010) Today's research: tomorrow's therapies. in Future oncology (London, England)

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Ahmad I (2011) HER2 overcomes PTEN (loss)-induced senescence to cause aggressive prostate cancer. in Proceedings of the National Academy of Sciences of the United States of America

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Ramsay AK (2011) ERK5 signalling in prostate cancer promotes an invasive phenotype. in British journal of cancer