Simon Brewster

Wnt signalling and prostate cancer

The Wnt signalling pathway plays a role in the direction of embryological development and maintenance of stem cell populations. Heritable alterations in genes encoding molecules of the Wnt pathway, including mutation and epigenetic events, have been demonstrated in a variety of cancers. It has been proposed that disruption of this pathway is a significant step in the development of many tumours. Interactions between β-catenin—the effector molecule of the Wnt pathway—and the androgen receptor highlight the pathways relevance to urological malignancy. Mutation or altered expression of Wnt genes in tumours may give prognostic information and treatments are being developed which target this pathway.

PREOPERATIVE p53, bcl-2, CD44 and E-CADHERIN IMMUNOHISTOCHEMISTRY AS PREDICTORS OF BIOCHEMICAL RELAPSE AFTER RADICAL PROSTATECTOMY

PURPOSE Since radical prostatectomy is performed to cure prostate cancer, identification of markers enabling preoperative prediction of relapse after radical prostatectomy is essential to counsel and select patients for adjuvant therapy. Aberrant p53, bcl-2, CD44 and E-cadherin immunohistochemistry has been associated with aggressiveness in prostate cancer. We assessed these biomarkers in biopsy and radical prostatectomy specimens as predictors of biochemical relapse. MATERIALS AND METHODS A total of 76 patients with untreated clinically localized prostatic adenocarcinoma underwent radical prostatectomy. Preoperative (prostate specific antigen, biopsy Gleason score) and postoperative (pathological stage and margin status) variables, biopsy and radical prostatectomy biomarker immunohistochemistry were correlated with relapse. Univariate and multivariate statistical analyses identified significant predictors. RESULTS Of the 76 patients 23 (30%) had relapse (mean followup 38 months). Aberrant p53, bcl-2, CD44 and E-cadherin expression was observed in 64, 12, 85 and 12% of biopsies and 57, 20, 64 and 49% of radical prostatectomy specimens, respectively. Biopsy Gleason 7 to 10 and biopsy p53, respectively, gave the highest positive and negative predictive values for relapse. Relapse occurred in 13% of patients with normal biopsy p53 and in half with aberrant p53. Multivariate analysis revealed Gleason score and p53 to be independent preoperative predictors (p = 0.01 and 0.02, respectively). Estimated risk of relapse was 3.5 times higher in patients with Gleason scores 7 to 10 and 24% higher in those with aberrant p53. Significant postoperative predictors were bcl-2, p53, Gleason score and margin status (p = 0.01, 0.01, 0.04 and 0.01, respectively). CONCLUSIONS Aberrant biopsy p53 is associated with a significantly worse outcome after radical prostatectomy than normal p53, highlighting a potential clinical role for p53. Postoperative p53 and bcl-2 were significant predictors of outcome after radical prostatectomy.

Silencing of the IGF1R gene enhances sensitivity to DNA-damaging agents in both PTEN wild-type and mutant human prostate cancer

The type 1 insulin-like growth factor receptor (IGF1R) is overexpressed in prostate cancer, and mediates proliferation, motility, and survival. Many prostate cancers harbor inactivating PTEN mutations, enhancing Akt phosphorylation. This activates the principal antiapoptotic pathway downstream of the IGF1R, calling into question the value of IGF1R targeting in this tumor. The aim of the current study was to assess the effect of IGF1R gene silencing in prostate cancer cells that lack functional PTEN protein. In human DU145, LNCaP and PC3 prostate cancer cells, transfection with IGF1R small interfering RNA induced significant enhancement of apoptosis and inhibition of survival, not only in PTEN wild-type DU145 but also in PTEN mutant LNCaP and PC3. This was attributed to attenuation of IGF signaling via Akt, ERKs and p38. In both DU145 and PC3, IGF1R knockdown led to enhancement of sensitivity to mitoxantrone, etoposide, nitrogen mustard and ionizing radiation. There was no sensitization to paclitaxel or 5-fluorouracil, which do not damage DNA, suggesting that chemosensitization results from impairment of the DNA damage response, in addition to removal of apoptosis protection. These results support the concept of IGF1R targeting in prostate cancer, and indicate that PTEN loss does not render tumor cells refractory to this strategy.

Urology and the Internet: an evaluation of Internet use by urology patients and of information available on urological topics

Objective To determine the use of the Internet by urological patients for obtaining information about their disease, and to conduct an evaluation of urological websites to determine the quality of information available.

Somatic Allelic Loss at the DCC, APC, nm23-H1 and P53 Tumor Suppressor Gene Loci in Human Prostatic Carcinoma

We present a restriction fragment length polymorphism (RFLP) analysis of 29 benign and 30 malignant prostatic tumors, using polymorphic DNA probes to the putative tumor suppressor genes DCC (Deleted in Colorectal Carcinoma; chromosome 18q21.3), nm23-H1 (17q21.3), APC (Adenomatous Polyposis Coli; 5q21) and p53 (17p13). Six of 23 evaluable cancers (26%) showed loss of heterozygosity (LOH) at DCC; 5 were advanced stage and one was clinically localized (p < 0.05). Mapping 18q deletions, another (advanced) cancer showed LOH at a locus distal to DCC (18q22), but no LOH at DCC. Three of 15 evaluable cancers (20%), all advanced, showed LOH at APC. Three of eight (38%) cancers, of which 2 were advanced, showed LOH at p53. One high grade/stage cancer of 21 (5%) showed LOH at nm23-H1 (and also at DCC). Combining data, allelic losses at either DCC, APC, or p53 genes were seen in 13% of localized cancers, but in 71% of advanced cancers (p < 0.002). Allelic loss involving nm23-H1 is rare in prostatic carcinoma. We suggest that loss of tumor suppressor genes DCC and/or an unidentified gene located distally on chromosome 18q, APC, or p53 may influence progression in prostatic carcinoma.

Loss of heterozygosity on chromosome 18q is associated with muscle-invasive transitional cell carcinoma of the bladder.

Somatic allelic loss is regarded as a hallmark of tumour-suppressor gene (TSG) inactivation. Thirty-one human bladder transitional cell carcinomas (TCCs) were examined for allelic loss at five chromosome 18q loci, including the DCC gene (deleted in colorectal carcinoma) and at chromosome 11p15 in a restriction fragment length polymorphism analysis. Allelic loss was observed at one or more 18q loci in 9/26 (35%) samples, associated with muscle-invasive disease (P < 0.02). Allelic loss was observed at DCC in 8/24 (33%) samples, associated with muscle-invasive disease (P = 0.05). Three out of the five evaluable recurrent TCCs exhibited allelic loss at DCC, two of which were superficial. No allelic losses were detected at other 18q loci in tumours which retained both DCC alleles. Allelic loss was observed at 11p15 in 5/20 (25%) tumours. These data suggest the presence of a late-acting TSG located on 18q in TCC bladder cancer. DCC is a candidate gene since it lies within the region of most common deletion (18q21.3-qter).

Chemosensitization of human prostate cancer using antisense agents targeting the type 1 insulin-like growth factor receptor

To assess the effect of the downregulation of type 1 insulin‐like growth factor receptor (IGF1R) on the chemosensitivity of prostate cancer cells. IGF1R is overexpressed by prostate cancer compared with benign prostatic epithelium and IGF1R expression commonly persists in androgen‐independent metastatic disease at levels comparable to those in the primary.

Rectal examination and urethral catheterization by medical students and house officers: taught but not used

Objective To assess the acquisition of skills in digital rectal examination (DRE) and urethral catheterization by medical students and house officers associated with a UK medical school, and to determine their confidence in these techniques.

HIGH-INTENSITY FOCUSED ULTRASOUND FOR LOCALIZED PROSTATE CANCER: INITIAL EXPERIENCE WITH A 2-YEAR FOLLOW-UP

To report on the short‐term functional and oncological results, from one institution, of high‐intensity focused ultrasound (HIFU) for treating localized prostate cancer.

Mutations in the AXIN1 Gene in Advanced Prostate Cancer

BACKGROUND The Wnt signalling pathway directs aspects of embryogenesis and is thought to contribute to maintenance of certain stem cell populations. Disruption of the pathway has been observed in many different tumour types. In bowel, stomach, and endometrial cancer, this is usually due to mutation of genes encoding Wnt pathway components APC or beta-catenin. Such mutations are rare in hepatocellular carcinomas and medulloblastomas with Wnt pathway dysfunction, and there, mutation in genes for other Wnt molecules, such as Axin, is more frequently found. OBJECTIVE Although evidence of abnormal activation of the Wnt pathway in prostate cancer has been demonstrated by several groups, APC and beta-catenin mutations are infrequent. We sought mutations in genes encoding Wnt pathway participants in a panel of prostate cancer clinical specimens and cell lines. DESIGN, SETTING, AND PARTICIPANTS DNA was obtained from 49 advanced prostate cancer specimens using laser microdissection followed by whole genome amplification and 8 prostate cancer cell lines. MEASUREMENTS The DNA samples were screened for mutations in the genes encoding APC, beta-catenin, and Axin. The subcellular distribution of beta-catenin expression was assessed in the clinical specimens using immunohistochemistry. RESULTS AND LIMITATIONS Abnormal patterns of beta-catenin expression, suggesting Wnt pathway dysregulation, were observed in 71% of specimens. One APC mutation, two beta-catenin gene mutations, and 7 DNA sequence variations in the Axin gene were detected. Four different Axin polymorphisms were also found in the cell lines. The study does not provide definite evidence that the observed sequence changes alter protein function, promoting neoplasia, but the potential functional relevance of these variants is discussed. CONCLUSIONS These data contribute to our understanding of the role of Wnt dysregulation in prostatic tumourigenesis and support the current interest in the pathway as a therapeutic target. Of particular interest, we identified three new potentially functionally relevant AXIN1 mutations.