Mark A. Rochester

Up-Regulation of Endothelial Delta-like 4 Expression Correlates with Vessel Maturation in Bladder Cancer

Purpose: Angiogenesis and vascular endothelial growth factor (VEGF) expression are associated with a poor outcome in bladder cancer. To understand more about the mechanisms, we studied the role of delta-like 4 (DLL4), an endothelial-specific ligand of the Notch signaling pathway, in bladder cancer angiogenesis. Experimental Design: The expression of DLL4, CD34, and VEGF were studied in a cohort of 60 bladder tumors and 10 normal samples using quantitative PCR. In situ hybridization was used to study the pattern of DLL4 expression in 22 tumor and 9 normal samples. Serial sections were also stained for CD34 and α-smooth muscle actin (α-SMA) using conventional immunohistochemistry. Results: The expression of DLL4 was significantly up-regulated in superficial (P < 0.01) and invasive (P < 0.05) bladder cancers. DLL4 expression significantly correlated with CD34 (P < 0.001) and VEGF (P < 0.001) expression. The in situ hybridization studies showed that DLL4 was highly expressed within bladder tumor vasculature. Additionally, DLL4 expression significantly correlated with vessel maturation as judged by periendothelial cell expression of α-SMA, 98.7% of DLL4-positive tumor vessels coexpressed α-SMA, compared with 64.5% of DLL4-negative tumor vessels (P < 0.001). High DLL4 expression may have prognostic value in superficial and invasive bladder. Conclusion: DLL4 expression is associated with vascular differentiation in bladder cancer; thus, targeting DLL4 may be a novel antiangiogenic therapy.

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.

The type 1 insulin-like growth factor receptor is over-expressed in bladder cancer

To analyse bladder cancer biopsies and investigate the pattern of expression of the type 1 insulin‐like growth factor receptor (IGF1R), a receptor tyrosine kinase that mediates tumour cell proliferation, motility and protection from apoptosis.

Depletion of the type 1 IGF receptor delays repair of radiation-induced DNA double strand breaks

BACKGROUND AND PURPOSE IGF-1R depletion sensitizes prostate cancer cells to ionizing radiation and DNA-damaging cytotoxic drugs. This study investigated the hypothesis that IGF-1R regulates DNA double strand break (DSB) repair. METHODS We tested effects of IGF-1R siRNA transfection on the repair of radiation-induced DSBs by immunoblotting and immunofluorescence for γH2AX, and pulsed-field gel electrophoresis. Homologous recombination (HR) was quantified by reporter assays, and cell cycle distribution by flow cytometry. RESULTS We confirmed that IGF-1R depletion sensitized DU145 and PC3 prostate cancer cells to ionizing radiation. DU145 control transfectants resolved radiation-induced DSBs within 24 h, while IGF-1R depleted cells contained 30-40% unrepaired breaks at 24 h. IGF-1R depletion induced significant reduction in DSB repair by HR, although the magnitude of the repair defect suggests additional contributory factors. Radiation-induced G2-M arrest was attenuated by IGF-1R depletion, potentially suppressing cell cycle-dependent processes required for HR. In contrast, IGF-1R depletion induced only minor radiosensitization in LNCaP cells, and did not influence repair. Cell cycle profiles were similar to DU145, so were unlikely to account for differences in repair responses. CONCLUSIONS These data indicate a role for IGF-1R in DSB repair, at least in part via HR, and support use of IGF-1R inhibitors with DNA damaging cancer treatments.

A randomized controlled trial of topical glyceryl trinitrate before transrectal ultrasonography‐guided biopsy of the prostate

1 Planas J, Morote J, Orsola A et al. The relationship between daily calcium intake and bone mineral density in men with prostate cancer. BJU Int 2007; 99 : 812–5 2 Chan JM, Giovannucci EL. Dairy products, calcium, and vitamin D and risk of prostate cancer. Epidemiol Rev 2001; 23 : 87–92 3 Tseng M, Breslow RA, Graubard BI, Ziegler RG. Dairy, calcium, and vitamin D intakes and prostate cancer risk in the National Health and Nutrition Examination Epidemiologic Follow-up Study cohort. Am J Clin Nutr 2005; 81 : 1147–54 4 Giovannucci E, Liu Y, Stampfer MJ, Willett WC. A prospective study of calcium intake and incident and fatal prostate cancer. Cancer Epidemiol Biomarkers Prev 2006; 15 : 203–10 5 Monteith GR, McAndrew D, Faddy HM, Roberts-Thomson SJ. Calcium and cancer: targeting Ca (2 + ) transport. Nat Rev Cancer 2007; 7 : 519–30 6 Greenspan SL, Nelson JB, Trump DL, Resnick NM. Effect of onceweekly oral alendronate on bone loss in men receiving androgen deprivation therapy for prostate cancer: a randomized trial. Ann Intern Med 2007; 146 : 416– 24 7 Michaelson MD, Kaufman DS, Lee H et al. Randomized controlled trial of annual zoledronic acid to prevent gonadotropin-releasing hormone agonist-induced bone loss in men with prostate cancer. J Clin Oncol 2007; 25 : 1038–42 8 Matsunaga S, Iguchi K, Usui S, Hirano K. Incadronate induces cell detachment and apoptosis in prostatic PC-3 cells. Anticancer Res 2007; 27 : 927–32

Genetics for urologists.

The ability to study the molecular and genetic basis of disease with an increasingly wide and sophisticated armoury of techniques will lead to enhanced understanding of the causes of disease, and so to the progression of gene‐directed therapy. The challenge ahead is in refining these therapeutic techniques to provide efficient and safe delivery of genetic material or gene‐silencing agents.