Frank vom Dorp

A new phospholipase-C–calcium signalling pathway mediated by cyclic AMP and a Rap GTPase

Stimulation of phosphoinositide-hydrolysing phospholipase C (PLC) generating inositol-1,4,5-trisphosphate is a major calcium signalling pathway used by a wide variety of membrane receptors, activating distinct PLC-β or PLC-γ isoforms. Here we report a new PLC and calcium signalling pathway that is triggered by cyclic AMP (cAMP) and mediated by a small GTPase of the Rap family. Activation of the adenylyl cyclase-coupled β2-adrenoceptor expressed in HEK-293 cells or the endogenous receptor for prostaglandin E1 in N1E-115 neuroblastoma cells induced calcium mobilization and PLC stimulation, seemingly caused by cAMP formation, but was independent of protein kinase A (PKA). We provide evidence that these receptor responses are mediated by a Rap GTPase, specifically Rap2B, activated by a guanine-nucleotide-exchange factor (Epac) regulated by cAMP, and involve the recently identified PLC-ɛ isoform.

Matrix metalloproteinases and their clinical relevance in urinary bladder cancer.

Matrix metalloproteinases (MMPs) have important roles in several cancer-supporting cellular processes, such as extracellular matrix (ECM) remodeling, angiogenesis, apoptosis, epithelial-to-mesenchymal transition and cell proliferation. This broad range of activity has led to considerable interest in the use of MMPs in the clinical setting as diagnostic or prognostic biomarkers and as therapeutic targets. Levels of the different MMPs can be measured in several sample types, including paraffin-embedded or fresh frozen tissue, serum, plasma and urine, and by various analytical methodologies, such as immunohistochemistry, real-time PCR, western and northern blot analyses, enzyme-linked immunosorbent assay and zymography. Several MMPs have been identified as having potential diagnostic or prognostic utility, whether alone or in combination with currently available diagnostic tests or imaging modalities. Although the early broad-spectrum anti-MMP agents showed a lack of efficacy, our continually improving understanding of the complex physiologic and pathologic roles of MMPs might enable the development of new MMP-specific and tumor-specific therapies. Accordingly, MMPs will continue to be the subjects of intensive research in bladder cancer.

Matrix metalloproteinase-7 as a marker of metastasis and predictor of poor survival in bladder cancer

Matrix metalloproteinases (MMPs) play an important role in tumor progression and metastasis. Here, we investigated the prognostic relevance of MMP‐7 in urinary bladder cancer. MMP‐7 gene expression was measured in tissue samples of 101 patients using quantitative real‐time PCR. Circulating MMP‐7 serum levels of 98 individuals (79 patients and 19 controls) were analyzed by enzyme‐linked immunosorbent assay. The results were compared with the clinical follow‐up data, performing Kaplan–Meier log‐rank test as well as univariate and multivariate Cox analysis. In representative cases, immunohistochemical analysis for MMP‐7 was performed. We detected significantly elevated MMP‐7 levels both in tissue and serum samples of patients with metastatic disease (P = 0.001 and P = 0.002). Multivariate analysis revealed that high MMP‐7 tissue expression and serum concentration are stage‐ and grade‐independent predictors of both metastasis‐free (hazard ratio [HR] = 3.80, 95% confidence interval [CI], 1.29–11.23, P = 0.016, and HR = 2.53, 95% CI, 1.01–6.37, P = 0.048) and disease‐specific survival (HR = 1.89, 95% CI, 1.00–3.55, P = 0.050 and HR = 1.95, 95% CI, 1.03–3.71, P = 0.041). Based on these findings, we conclude that MMP‐7 is a promising marker to detect present and to predict future metastasis. Serum MMP‐7 analysis provides information about the risk of metastasis before surgery which could help to optimize therapeutic procedures. Furthermore, high MMP‐7 tissue and/or serum levels could identify patients most likely to benefit from early adjuvant chemotherapy.

Alterations in the tumor suppressor gene p16(INK4A) are associated with aggressive behavior of penile carcinomas.

Alterations in the p16/cyclinD1/Rb and ARF/Mdm2/p53 pathways are frequent events in the pathogenesis of squamous cell carcinomas. Different mechanisms of p16 regulation have been described for penile carcinomas so far. Therefore, expression of p16 and p53 was immunohistochemically detected with monoclonal antibodies in 52 primary invasive penile squamous cell carcinomas. The carcinomas were analyzed for allelic loss (LOH) in p16INK4A and p53, as well as for mutations in the p16INK4A and the p53 gene. In addition, we examined the promoter status of p16INK4A by methylation-specific PCR. The presence of human papilloma virus (HPV) 6/11, HPV 16 and HPV 18 DNA was analyzed by PCR. Data were compared to clinical data. Concerning p16, 26 (50%) tumors showed positive immunohistochemistry, 32 (62%) tumors showed allelic loss and 22 tumors (42%) showed promoter hypermethylation. All tumors with negative p16 immunohistochemistry showed LOH near the p16INK4A locus and/or hypermethylation of the p16INK4A promoter. HPV 16 DNA was detected in 17 tumors, ten of them with positive p16 immunostaining. The remaining seven tumors with negative p16 staining showed allelic loss and/or promoter hypermethylation. Evidence of lymph node metastasis was significantly associated with negative p16 immunohistochemistry as well as with combined LOH and promoter hypermethylation (p = 0.003 and p = 0.018, respectively). Allelic loss around p53 was found in 22 tumors (42%), and seven mutations of the p53 gene could be demonstrated in our tumors. No correlations could be found between any p53 alteration and clinical parameters.

Rap2B-Dependent Stimulation of Phospholipase C-ε by Epidermal Growth Factor Receptor Mediated by c-Src Phosphorylation of RasGRP3

ABSTRACT Receptor tyrosine kinase regulation of phospholipase C-ε (PLC-ε), which is under the control of Ras-like and Rho GTPases, was studied with HEK-293 cells endogenously expressing PLC-coupled epidermal growth factor (EGF) receptors. PLC and Ca2+ signaling by the EGF receptor, which activated both PLC-γ1 and PLC-ε, was specifically suppressed by inactivation of Ras-related GTPases with clostridial toxins and expression of dominant-negative Rap2B. EGF induced rapid and sustained GTP loading of Rap2B, binding of Rap2B to PLC-ε, and Rap2B-dependent translocation of PLC-ε to the plasma membrane. GTP loading of Rap2B by EGF was inhibited by chelation of intracellular Ca2+ and expression of lipase-inactive PLC-γ1 but not of PLC-ε. Expression of RasGRP3, a Ca2+/diacylglycerol-regulated guanine nucleotide exchange factor for Ras-like GTPases, but not expression of various other exchange factors enhanced GTP loading of Rap2B and PLC/Ca2+ signaling by the EGF receptor. EGF induced tyrosine phosphorylation of RasGRP3, but not RasGRP1, apparently caused by c-Src; inhibition of c-Src interfered with EGF-induced Rap2B activation and PLC stimulation. Collectively, these data suggest that the EGF receptor triggers activation of Rap2B via PLC-γ1 activation and tyrosine phosphorylation of RasGRP3 by c-Src, finally resulting in stimulation of PLC-ε.

Prospective randomized double-blind multicentre phase II study comparing gemcitabine and cisplatin plus sorafenib chemotherapy with gemcitabine and cisplatin plus placebo in locally advanced and/or metastasized urothelial cancer: SUSE (AUO-AB 31/05).

To evaluate the efficacy and safety of gemcitabine and cisplatin in combination with sorafenib, a tyrosine‐kinase inhibitor, compared with chemotherapy alone as first‐line treatment in advanced urothelial cancer.

Angiogenic Switch of Angiopietins-Tie2 System and Its Prognostic Value in Bladder Cancer

Purpose: Vascular endothelial growth factor (VEGF), angiopoietins (Ang-1 and Ang-2), and their receptor Tie2 are critically involved in both normal and pathologic angiogenesis. The aim of this study was to explore the role of Ang-1, Ang-2, VEGF, and Tie2 in the development and progression of bladder cancer as well as to examine their prognostic value in this tumor type. Experimental Design: Tumor samples of 113 bladder cancer patients, normal bladder epithelium of 5 noncancer patients, and two low-grade (UMUC3 and RT4) and two high-grade (J82 and T24) bladder cancer cell lines were analyzed by quantitative real-time PCR. The expression data were analyzed performing Wilcoxon rank-sum and Kaplan-Meier log-rank tests as well as univariate Cox analyses and Cox proportional hazards regression model. Results: In tissues of noninvasive bladder tumors, Ang-1 expression was significantly lower (P < 0.001), whereas VEGF expression was significantly higher (P = 0.031) than in normal bladder tissue. These findings were also confirmed at the protein level by immunohistochemistry. In contrast, Tie2 and Ang-2 abundance in tumor did not differ significantly from that in normal bladder tissue. Multivariate analysis identified Ang-2 as a strong and independent predictor of tumor recurrence [hazard ratio (HR), 10.18; 95% confidence interval (95% CI), 2.69-38.49; P < 0.001] and Tie2 expression as an independent favorable prognostic factor for both metastasis (HR, 0.31; 95% CI, 0.11-0.89; P = 0.029) and disease-specific survival (HR, 0.25; 95% CI, 0.10-0.62; P = 0.003). Conclusions: These data show the strongest change in expression of VEGF and Ang-1 in superficial bladder cancer in comparison with normal bladder epithelium and the invasive tumor stages. The prognostic significance of Ang-2 and Tie2 underlines the essential role of angiopoietins-Tie2 system in progression of bladder cancer.

Elevated serum matrix metalloproteinase 7 levels predict poor prognosis after radical prostatectomy

Elevated matrix metalloproteinase‐7 (MMP‐7) tissue expression and serum concentration have been shown to be associated with cancer progression and metastasis. The aim of our study was to assess the prognostic value of preoperative circulating MMP‐7 levels in serum samples of patients with clinically localized prostate cancer. Furthermore, we compared the serum MMP‐7 levels between patients with organ confined and metastatic prostate cancer. MMP‐7 levels were measured in 93 patients with localized prostate cancer, 13 patients with distant bone metastasis and in sera of 19 controls using enzyme‐linked immunosorbent assay. The results were compared to the clinical follow‐up data. We did not find any significant difference in MMP‐7 serum levels between patients and controls (p = 0.268). Circulating MMP‐7 serum concentration was significantly elevated in patients with distant metastasis (p < 0.001). For the detection of distant prostate cancer metastasis, using a cut‐off value of 3.7 ng/ml, a specificity of 69% and a sensitivity of 92% were observed. Multivariate analysis identified high MMP‐7 serum concentration as an independent risk factor for prostate cancer‐related death both in a preoperative and a postoperative model (p = 0.003 and 0.018, respectively). Furthermore, the evaluation of predictive models revealed that addition of serum MMP‐7 levels to the preoperatively available predictors improves prognostic accuracy (the concordance index increased from 0.631 to 0.734 when MMP‐7 was included). Based on these, we concluded that MMP‐7 is a potential marker to identify patients with metastatic prostate cancer. In clinically localized prostate cancer, MMP‐7 may provide independent prognostic information, thereby helping to optimize therapy decisions.

Validation of Circulating MMP-7 Level as an Independent Prognostic Marker of Poor Survival in Urinary Bladder Cancer

Molecular marker analyses aiming a more accurate disease characterization and risk stratification of cancer patients provided several promising marker candidates in the last few years. However, recent reviews underlined the paramount importance of validation, since many of the initially promising results could not be confirmed in independent patient cohorts. If serum or plasma is a more appropriate sample to test for prognostic markers is a matter of debate. We recently found serum MMP-7 levels to correlate with poor patients’ prognosis in urinary bladder cancer. In this study, we examined associations of the MMP-7 plasma levels with clinical follow-up data in an independent cohort of bladder cancer patients to validate our former results and to assess if plasma is also suitable for MMP-7 analysis. Plasma levels of 97 patients and 22 controls were analyzed, using enzyme-linked immunosorbent assay. Associations between MMP-7 plasma concentrations and clinical data were assessed applying both univariate and multivariate analysis. Plasma MMP-7 levels were significantly higher in patients than in controls. Similarly to our former findings in sera, high MMP-7 plasma levels proved to be significant and independent predictors of both overall and disease-specific survival. In addition, we observed a metastasis-specific difference in MMP-7 levels between serum and plasma. In summary, we confirmed the prognostic relevance of circulating MMP-7 levels in an independent cohort of patients and concluded that circulating MMP-7 levels may help to identify bladder cancer patients at high-risk of disease progression who could benefit from an adjuvant chemotherapy or from an extended lymph node dissection.

High insulin-like growth factor mRNA-binding protein 3 (IMP3) protein expression is associated with poor survival in muscle-invasive bladder cancer.

Whats known on the subject? and What does the study add?