Prostate Cancer

Cell Transformation Team

Section: Section of Molecular Carcinogenesis

Prostate cancer is the common cancer in men in the UK with nearly 30,000 cases diagnosed annually. A particular current problem is that it is not possible to predict how early prostate cancer still localised to the prostate (for example, detected by the PSA test) will behave. Some cases may remain dormant for many years without progressing while others will progress rapidly to malignancy. Further, current radiotherapy and surgical treatments lead to impotence and other harmful side effects to surrounding organs in 50-80% of patients. The goal of the work we are undertaking is to use information from the Human Genome Project to identify markers that can be used to distinguish dormant from aggressive early prostate cancers. This is important because such markers can be used to identify aggressive cancers early so that they may be treated and could minimise treatment for dormant tumours. This programme of prostate cancer forms part of the NCRI South of England Prostate Cancer Collaborative.

Transcription factor E2F3 overexpressed in prostate cancer independently predicts clinical outcome

Investigators: A Falconer, AR Dodson, N Dennis, A Fletcher, C Southgate, A Dowe, D Dearnaley, S Jhavar, R Eeles, A Feber, CS Cooper; in collaboration with CS Foster and AR Dodson at the University of Liverpool

External Funding: NCRI, Cancer Research UK

E2F transcription factors, including E2F3, directly modulate expression of EZH2. Recently, overexpression of the EZH2 gene has been implicated in the development of human prostate cancer. In tissue microarray studies we now show that expression of high levels of nuclear E2F3 occurs in a high proportion (98/147, 67%) of human prostate cancers, but is a rare event in non-neoplastic prostatic epithelium suggesting a role for E2F3 overexpression in prostate carcinogenesis. Patients with prostate cancer exhibiting immunohistochemically detectable nuclear E2F3 expression have poorer overall survival (P=0.0022) and cause-specific survival (P=0.0047) than patients without detectable E2F3 expression. When patients are stratified according to the maximum percentage of E2F3-positive nuclei identified within their prostate cancers (up to 20, 21-40%, etc) there is an increasingly significant associated between E2F3 staining and risk of death both for overall survival (P=0.0014) and for cause-specific survival (P=0.0004). Multivariate analyses select E2F3 expression as an independent factor predicting overall survival (unstratified P=0.0103, stratified P=0.0086) and cause-specific survival (unstratified P=0.0288, stratified P=0.0072). When these results are considered together with published data on EZH2 and on the E2F3 control protein pRB, we concluded that the pRB-E2F3-EZH2 control axis may have a critical role in modulating aggressiveness of individual human prostate cancer.

Expression analysis onto microarrays of randomly selected cDNA clones highlights HOXB13 as a marker of human prostate cancer

Investigators: S Edwards, C Campbell, P Flohr, J Shipley, I Giddings, R te-Poele, AR Dodson, CS Foster, J Clark, S Jhavar, G Kovacs, CS Cooper; in collaboration with CS Foster and AR Dodson, University of Liverpool, and G Kovacs at the University of Heidelberg

External Funding: NCRI, Cancer Research UK

In a strategy aimed at identifying novel markers of human prostate cancer, we performed expression analysis using microarrays of clones randomly selected from a cDNA library prepared from the LNCaP prostate cancer cell line.  Comparisons of expression profiles in primary human prostate cancer, adjacent normal prostate tissue, and a selection of other (non-prostate) normal human tissues, led to the identification of a set of clones that were judged as the best candidate markers of normal and/or malignant prostate tissue.  DNA sequencing of the selected clones revealed that they included 10 genes that had previously been established as prostate markers: NKX3.1, KLK2, KLK3 (PSA), FOLH1 (PSMA), STEAP2, PSGR, PRAC, RDH11, Prostein and FASN.  Following analysis of the expression patterns of al selected and sequenced genes through interrogation of SAGE databases, a further three genes from our clone set, HOXB13, SPON2 and NCAM2, emerged as additional candidate markers of human prostate cancer.  Quantitative RT-PCR demonstrated the specificity of expression of HOXB13 in prostate tissue and revealed its ubiquitous expression in a series of 37 primary prostate cancers and 20normal prostates.  The results demonstrated the utility of this expression-microarray approach in hunting for new markers of individual human cancer types.

Construction of tissue microarrays from prostate needle biopsy specimens

Investigators: Jhavar S, Corbishley CM, Dearnaley D, Fisher C, Falconer A, Parker C, Eeles R, Cooper CS

Funding: NCRI, Cancer Research UK

Needle biopsy specimens are taken at the time of diagnosis from many human malignancies, including oral cancer, breast cancer, sarcomas, prostate cancer and lymph node masses. In prostate cancer, for example, examination of needle biopsy specimens yields valuable information, including Gleason grade and the tumour extent, that facilitates decision-making on the appropriate treatment. If tests are to be developed that will allow the prediction of clinical behaviour of patients diagnosed with prostate cancer, for example, following prostate-specific antigen (PSA) screening, it must be possible to perform the test on biological specimens obtained from the patients at the time of diagnosis, which would usually only include trans-rectal ultrasound (TRUS), guided needle biopsy specimens, blood or urine.

We have developed a simple and highly reliable technique for constructing tissue microarrays (TMAs) from prostatic needle biopsies. Serial sectioning of the TMAs, called ‘Checkerboard TMAs’, facilitated expression analysis of multiple proteins using IHC markers, in total, 100% of the analysed biopsies within the TMA both preserved their antigenicity and maintained their morphology. Checkerboard TMAs will allow the use of needle biopsies (i) alongside other tissue specimens (trans-urethal resection of prostates and prostatectomies in the case of prostate cancer) in clinical correlation studies when searching for new prognostic markers, and (ii) in a diagnostic context for assessing expression of multiple proteins in cancers from patients prior to treatment.