Research

Our clinical practice informs and underpins the research. We have the largest NHS practice in robotic prostatectomy: biorepositories from this, and from ProtecT (the largest ever surgical randomised controlled trial in prostate cancer) have led to important collaborative research with Doug Easton at the Strangeways Research Laboratory and Ros Eeles at the Institute of Cancer Research (ICR) (Al Olama et al., Nat Genet 2009; 41: 1058; Eeles et al., Nat Genet 2009; 41: 1116). Another collaborative project with Colin Cooper at the ICR (CancerMAP) is now completed and undergoing analysis for expression profiling stratified by TMPRSS2-ERG status. A further collaborative application is under consideration for in-depth sequencing of prostate cancers.

Ian Mills has left to become a Group Leader at the Centre for Molecular Medicine in Oslo and Charlie Massie has left to take up a new post-doctoral position. We have been joined by Lee Fryer, Mohammad Asim and Gökmen Altay. Frank O'Brien has joined the clinical academic department to establish joint research in renal cancer with Tim Eisen (Department of Oncology).

Castration-independent prostate cancer

Androgen receptor (AR) signalling is maintained in most men with castration-independent prostate cancer and new management and therapeutic approaches are needed. Our goals are to identify and characterise markers that better predict progression, and to identify more effective treatments. AR remains the primary target for treatment and the rationale remains strong for better targeting of this pathway and to uncover biomarkers. We are aiming to work with human tissue wherever possible, but our portfolio now includes pre-clinical in vivo models, which will give us better information on how individual genes function throughout tumour development. Examples include p53/pRb or PTEN prostate specific knockouts, which express the luciferase gene in tumour cells and makes them traceable though bioluminescence imaging (BLI).

Main discoveries

We have now completed ChIP sequencing for the androgen receptor coupled with ChIP for Pol II. This research has led to a new understanding about how the AR binds to the genome and discoveries about how this influences major metabolic signalling pathways. Two papers have been completed and a third is being written on our ChIP sequencing studies on human tissue.

We have also taken forward one of the SNP risk alleles we reported last year in a paper in Nature Genetics to begin functional studies (Whitaker et al., PLoS ONE 2010a; 5: e13363; Whitaker et al., Prostate 2010b; 70: 333) and have completed mechanistic studies on a biomarker reported last year (Thirkettle et al., Clin Cancer Res 2009a; 15: 3003; Thirkettle et al., Oncogene 2009b; 28: 3663).

Figure 1
An example of MSMB staining in prostate cancer. The white arrow indicates strongly stained benign glands. Black arrows show cancerous glands.

Figure 2
MSMB staining in tissue samples from 1456 samples shows that MSMB is switched off in cancer and pre-malignant lesions.

1. ChIP sequencing studies (Massie and Mills, Meth Mol Biol 2009; 505: 123; Zecchini and Mills, J Cell Biochem 2009; 107: 19)
   We have comprehensively mapped AR binding sites in two models of prostate cancer using ChIP-seq and mapped transcriptionally active targets using ChIP-seq for phosphorylated RNA polymerase II, combined with expression profiling. This approach identified thousands of novel targets, defined distinct characteristics of transcriptionally active AR binding sites and identified signalling pathways directly regulated by the AR. Amongst these, we identified calcium/calmodulin kinase kinase 2 (CAMKK2) as over-expressed in castrate resistant prostate cancer and as being functionally important for proliferation. Our data provide new direct links between the AR and signalling pathways and offer the potential for novel therapeutic interventions. We are now expanding these studies into human material and have discovered several novel binding sites that appear to be functional.
2. Studies on MSMB (PSP94)
   Our recent collaborative genome-wide association studies have shown an association of a SNP two base pairs upstream of the 5'UTR of the microseminoprotein-beta (MSMB) gene with an increased risk of developing the prostate cancer (Eeles et al., Nat Genet 2009; 41: 1116). MSMB expression is high in normal and benign prostate tissue and lowered or lost in prostate cancer, suggesting that it might be a useful tissue biomarker for prostate cancer diagnosis (Figures 1 and 2). Members of the cysteine-rich secretory protein family and laminin receptors have been shown to bind MSMB at the cell surface and in serum, thereby regulating apoptosis. Both full length MSMB and a short peptide comprised of amino acids 31-45 have been tested for potential therapeutic benefit in mouse models and humans. Our recent data also show links between the risk allele in normal prostate and levels of expression (Figure 3). MSMB has potential as a biomarker of prostate cancer development, progression and recurrence and potentially as a target for therapeutic intervention (Whitaker et al., PLoS ONE 2010a; 5: e13363; Whitaker et al., Prostate 2010b; 70: 333).
3. Studies on HES6 (Vias et al., Prostate 2007; 67: 190; Vias et al., BMC Med Genomics 2008; 1: 17)
   A neuroendocrine profile is associated with castration-independence. We have found that a pro-neural expression signature - including over-expression of Ascl1, HES6, and neurotensin - is associated with advanced and castration-independent prostate cancer, and that transduction of androgen sensitive prostate cancer cells with Hes6 delivers a more aggressive phenotype. We are now studying the interaction between HES6 and c-myc and are testing the role that HES6 plays in castration independent cell growth in vivo.
4. Studies on beta-arrestin1 (ARRB1: Borlido et al., Traffic 2009; 10: 1209)
   ARRB1 plays a role in cancer progression and some tumours show elevated levels in the nucleus where it may regulate gene expression via epigenetic mechanisms. We aim to determine the potential role played by ARRB1 in prostate cancer and to identify novel biomarkers and therapeutic targets. Prostate cancer displays elevated levels of ARRB1 that correlate with stage and aggressiveness, it is also present in the nucleus in high-grade cancer. We have identified several genes whose expression is differentially regulated by ARRB1 and they are involved in processes such as the cell cycle, cell motility and metabolism. Using ChIP‑sequencing, we have identified several binding sites for endogenous ARRB1, which reside mainly in enhancers or proximal promoters and include genes involved in the unfolded protein response and autophagy. A paper has been submitted.

Figure 3
MSMB also changes with the presence or absence of a risk allele found via genome wide association studies conducted in collaboration with Doug Easton (Strangeways Research Laboratory) and Ros Eeles (ICR).