Urological Research

We are a laboratory-based group with a strong surgical focus on prostate cancer.

We have the largest NHS practice in robotic prostatectomy in the UK, which has proved to be very important in contributing to a well-characterised human biorepository at the CRI. In the past year this has led to a new Cancer Research UK project, the CancerMaP project, jointly run with Colin Cooper of the Institute of Cancer Research (ICR), which will generate DNA, mRNA and miRNA from prostate cancers stratified by TMPRSS2-ERG status.

Over the past year, the project team has grown with the appointment of Vincent Gnanapragasam (HEFCE funded Senior Lecturer, and Cancer Research UK Clinician Scientist). We are a multi-disciplinary group, which includes a substantial number of clinical academic trainees in addition to biologists. The main purpose of the group is to identify the mechanisms that underpin castration independent prostate cancer, with the intention of identifying potential therapeutic targets or markers that might predict clinical outcome of prostate cancer. A critical component over the past year has been to further develop the clinical material required for testing out new potential markers. This has included establishing tissue microarrays, and collections of serum, plasma and urine in addition to fresh frozen material.

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 ways of targeting this disease. The AR as a transcription factor remains the primary target for treatment and the rationale remains strong for better targeting of this pathway and to uncover biomarkers. Because it is unlikely that any single protein will prove to be critical as a marker or a therapeutic target a rational approach is to unravel transcriptional networks by integrating chromatin immuno-precipitation (ChIP), expression, and SNP data. Over the last five years, we have characterised AR binding sites and gene targets using ChIP and expression arrays (Figure 1).

The same approaches are now being applied to other transcription factors (Ascl1 and Hes6) and co-regulators (HIP1) which we have shown to be over-expressed and, in the case of HIP1 and Hes6, to associate with the AR. It is possible that targeting transcription factors/co-regulators other than the AR may reduce AR signalling sufficiently to produce a therapeutic response. To test this idea further we need more appropriate models and better characterised sets of clinical material, which we hope to have in the near future.

Main discoveries

Our main discoveries are highlighted below:

1. We have shown how the AR binds to the human genome and using ChIP-on-chip have found that it usually binds in a half-site (rather than as a palidromic dimer) and that frequently there is co-enrichment for other transcription factors such as Foxa1, ETS and GATA, several being of functional importance (Massie et al., EMBO Rep. 2008; 8:871; Massie and Mills, EMBO Rep. 2008; 9:337).
2. A neuro-endocrine 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 Hes6 silencing reduced neural gene expression and invasiveness of prostate cancer (Vias et al., Prostate 2007; 67:190; Vias et al., BMC Med. Genomics 2008; 1:17; Vias et al., Trends Mol. Med. 2008; 14:486).
3. Certain endocytic adaptors interact with growth factor receptors and translocate to the nucleus where their function is unclear. One of them, a prognostic marker for prostate cancer called Huntingtin interacting protein 1 (HIP1), undergoes nuclear translocation in response to androgens, silencing HIP1 increased AR degradation downstream signalling (Mills et al., J. Cell Biol. 2005; 170:191; Massie and Mills, Nat. Rev. Cancer 2006; 6:403). Further extension of this work over the past year has identified that another adaptor protein, which is known to be important in prostate cancer (clathrin) is associated with the mitotic spindle, but is context dependent in terms of cell division (Borlido et al., PLoS ONE 2008; 3:e3115).
4. In human tissue and fluid, we have assessed a number of candidate targets that interact with the AR as diagnostic or prognostic markers (Whitaker et al., Prostate 2008; 68:1196) including some discovered though our collaborative genetic studies (see 5b below).
5. We have set up collaborations to study how the AR enters the nucleus, to identify novel susceptibility loci and to profile tissue (genomics) and plasma samples (proteomics).
   1. With Murray Stewart (MRC Laboratory of Molecular Biology, Cambridge) we identified the structural residues within the AR responsible for AR binding to importin-alpha, and that certain AR mutants have altered intra-cellular distribution (Cutress et al., J. Cell Sci. 2008; 121:957).
   2. With Rosalind Eeles (ICR) and Douglas Easton (Strangeways Research Laboratory, Cambridge), we identified novel susceptibility loci for prostate cancer using a genome wide scanning approach (Eeles et al., Nat. Genet. 2008; 40:216; Ghoussaini et al., J. Natl. Cancer Inst. 2008; 100:962).
   3. We have profiling collaborations with industry: Philips (serum proteomics), DECODE, ALMAC (genomics); and with Colin Cooper at the ICR (genomics).

Conclusions

We are planning to extend our studies in four main areas:

1. Increasing the use of carefully characterised biological materials in prostate cancer to test out targets. These include biopsy materials taken before and after androgen ablation in man, fresh tissue with extraction of DNA, mRNA and miRNA stratified by TMPRSS2 / ERG status, and TMAs and liquid based materials.
2. Continued studies of how the AR functions to include carefully targeted high throughput siRNA screens and ChIP sequencing approaches.
3. Studies in model systems to determine the functional impact of Ascl1 and Hes6 on neuro-endocrine differentiation in prostate cancer.
4. Studies of HIP1 and β-arrestin to determine how these adaptor proteins contribute to castration independent prostate cancer.

References

Please see Publications page (left-hand menu)