Karsten Gravdal

A Switch from E-Cadherin to N-Cadherin Expression Indicates Epithelial to Mesenchymal Transition and Is of Strong and Independent Importance for the Progress of Prostate Cancer

Purpose: Cell adhesion molecules are of crucial importance in cancer invasion and metastasis. Epithelial to mesenchymal transition, characterized by reduced E-cadherin and increased N-cadherin expression, has been recognized as a feature of aggressive tumors, but the importance of this phenotype has not been settled in human prostate cancer. We here present novel data, with special focus on the independent relationship between an E-cadherin to N-cadherin switch (EN-switch) and patient prognosis. Experimental Design: Tissue microarray sections from a consecutive series of 104 radical prostatectomies during 1988 to 1994 with detailed clinicopathologic data and long follow-up were studied immunohistochemically for the expression of E-cadherin, N-cadherin, P-cadherin, β-catenin, and p120CTN. Results: Low E-cadherin expression was significantly associated with adverse clinicopathologic features, whereas other biomarkers were mostly related to Gleason score. In univariate survival analyses, cadherin switching (high N-cadherin and low E-cadherin) showed strong and significant associations with multiple end points of progression and cancer-specific death. Expression of the “basal cell marker” P-cadherin was associated with shorter time to skeletal metastasis (P = 0.036). In multivariate analysis of time to clinical recurrence, the “EN-switch” (hazard ratio, 4.3; P < 0.0005) had strong and independent prognostic effect, together with Gleason score. Conclusion: These novel data unravel the importance of epithelial to mesenchymal transition for prostate cancer progression, and demonstration of a switch from E-cadherin to N-cadherin expression could have significant effect on the care of prostate cancer patients.

Expression of EZH2 and Ki-67 in colorectal cancer and associations with treatment response and prognosis

Background:Enhancer of zeste homologue 2 (EZH2) is a member of the Polycomb group of genes that is involved in epigenetic silencing and cell cycle regulation.Methods:We studied EZH2 expression in 409 patients with colorectal cancer stages II and III. The patients were included in a randomised study, and treated with surgery alone or surgery followed by adjuvant chemotherapy.Results:EZH2 expression was significantly related to increased tumour cell proliferation, as assessed by Ki-67 expression. In colon cancer, strong EZH2 expression (P=0.041) and high proliferation (⩾40%; P=0.001) were both associated with better relapse-free survival (RFS). In contrast, no such associations were found among rectal cancers. High Ki-67 staining was associated with improved RFS in colon cancer patients who received adjuvant chemotherapy (P=0.001), but not among those who were treated by surgery alone (P=0.087). In colon cancers stage III, a significant association between RFS and randomisation group was found in patients with high proliferation (P=0.046), but not in patients with low proliferation (P=0.26). Multivariate analyses of colon cancers showed that stage III (hazard ratio (HR) 4.00) and high histological grade (HR 1.80) were independent predictors of reduced RFS, whereas high proliferation indicated improved RFS (HR 0.55).Conclusion:Strong EZH2 expression and high proliferation are associated features and both indicate improved RFS in colon cancer, but not so in rectal cancer.

Prosaposin inhibits tumor metastasis via paracrine and endocrine stimulation of stromal p53 and Tsp-1

Metastatic tumors can prepare a distant site for colonization via the secretion of factors that act in a systemic manner. We hypothesized that non- or weakly metastatic human tumor cells may act in an opposite fashion by creating a microenvironment in distant tissues that is refractory to colonization. By comparing cell lines with different metastatic potential, we have identified a tumor-secreted inhibitor of metastasis, prosaposin (Psap), which functions in a paracrine and endocrine fashion by stimulating the expression of thrombospondin-1 (Tsp-1) in fibroblasts present in both primary tumors and distant organs, doing so in a p53-dependent manner. Introduction of Psap in highly metastatic cells significantly reduced the occurrence of metastases, whereas inhibition of Psap production by tumor cells was associated with increased metastatic frequency. In human prostate cancer, decreased Psap expression was significantly associated with metastatic tumors. Our findings suggest that prosaposin, or other agents that stimulate p53 activity in the tumor stroma, may be an effective therapy by inhibition of the metastatic process.

Bone Marrow-Derived Gr1+ Cells Can Generate a Metastasis-Resistant Microenvironment Via Induced Secretion of Thrombospondin-1

UNLABELLED Metastatic tumors have been shown to establish permissive microenvironments for metastases via recruitment of bone marrow-derived cells. Here, we show that metastasis-incompetent tumors are also capable of generating such microenvironments. However, in these situations, the otherwise prometastatic Gr1(+) myeloid cells create a metastasis-refractory microenvironment via the induction of thrombospondin-1 (Tsp-1) by tumor-secreted prosaposin. Bone marrow-specific genetic deletion of Tsp-1 abolished the inhibition of metastasis, which was restored by bone marrow transplant from Tsp-1(+) donors. We also developed a 5-amino acid peptide from prosaposin as a pharmacologic inducer of Tsp-1 in Gr1(+) bone marrow cells, which dramatically suppressed metastasis. These results provide mechanistic insights into why certain tumors are deficient in metastatic potential and implicate recruited Gr1(+) myeloid cells as the main source of Tsp-1. The results underscore the plasticity of Gr1(+) cells, which, depending on the context, promote or inhibit metastasis, and suggest that the peptide could be a potential therapeutic agent against metastatic cancer. SIGNIFICANCE The mechanisms of metastasis suppression are poorly understood. Here, we have identified a novel mechanism whereby metastasis-incompetent tumors generate metastasis-suppressive microenvironments in distant organs by inducing Tsp-1 expression in the bone marrow–derived Gr1+myeloid cells. A 5-amino acid peptide with Tsp-1–inducing activity was identified as a therapeutic agent against metastatic cancer.

Expression of bFGF/FGFR-1 and vascular proliferation related to clinicopathologic features and tumor progress in localized prostate cancer

Microvessel density (MVD) has been associated with progression of prostate cancer. Although basic fibroblast growth factor (bFGF) is a known endothelial mitogen, the prognostic role of bFGF and its receptor FGFR-1 in prostate cancer has been controversial. The aim of our study was to examine the tissue distribution and prognostic significance of bFGF, FGFR-1, and microvascular proliferation. Sections from 104 radical prostatectomy specimens were examined by factor VIII/Ki-67 staining for proliferating capillary index (PCI) and MVD, and tissue microarray sections were immunostained for bFGF and FGFR-1. Increased PCI (median 0.49%) was related to strong stromal expression of bFGF (P=0.003) but was without prognostic impact. Strong bFGF staining was associated with well-differentiated tumors, no capsular penetration, low serum-prostate-specific antigen (s-PSA), low tumor cell proliferation, and increased time to biochemical failure (P=0.007), and was of independent prognostic importance in multivariate survival analysis. bFGF expression in vessels was associated with low MVD (P=0.0003). In contrast, strong tumor cell FGFR-1 expression was related to high preoperative s-PSA. Thus, increased stromal and vessel bFGF was associated with less aggressive tumors. Our findings indicate a complex relationship between bFGF/FGFR-1 expression and prognosis of prostate cancer. Vascular proliferation revealed no prognostic impact in this study.

1.5-T multiparametric MRI using PI-RADS: a region by region analysis to localize the index-tumor of prostate cancer in patients undergoing prostatectomy

Background The use of multiparametric magnetic resonance imaging (mpMRI) to detect and localize prostate cancer has increased in recent years. In 2010, the European Society of Urogenital Radiology (ESUR) published guidelines for mpMRI and introduced the Prostate Imaging Reporting and Data System (PI-RADS) for scoring the different parameters. Purpose To evaluate the reliability and diagnostic performance of endorectal 1.5-T mpMRI using the PI-RADS to localize the index tumor of prostate cancer in patients undergoing prostatectomy. Material and Methods This institutional review board IRB-approved, retrospective study included 63 patients (mean age, 60.7 years, median PSA, 8.0). Three observers read mpMRI parameters (T2W, DWI, and DCE) using the PI-RADS, which were compared with the results from whole-mount histopathology that analyzed 27 regions of interest. Inter-observer agreement was calculated as well as sensitivity, specificity, positive predictive value (PPV), and negative predicted value (NPV) by dichotomizing the PI-RADS criteria scores ≥3. A receiver-operating curve (ROC) analysis was performed for the different MR parameters and overall score. Results Inter-observer agreement on the overall score was 0.41. The overall score in the peripheral zone achieved sensitivities of 0.41, 0.60, and 0.55 with an NPV of 0.80, 0.84, and 0.83, and in the transitional zone, sensitivities of 0.26, 0.15, and 0.19 with an NPV of 0.92, 0.91, and 0.92 for Observers 1, 2, and 3, respectively. The ROC analysis showed a significantly increased area under the curve (AUC) for the overall score when compared to T2W alone for two of the three observers. Conclusion 1.5 T mpMRI using the PI-RADS to localize the index tumor achieved moderate reliability and diagnostic performance.

WDR19 expression is increased in prostate cancer compared with normal cells, but low-intensity expression in cancers is associated with shorter time to biochemical failures and local recurrence

Purpose: Prostate cancer is the third leading cause of cancer death in the United States, following lung and colorectal cancer. We previously identified WDR19 as a prostate-specific, androgen-regulated gene. Here, we evaluate its utility as a prostate cancer tissue marker for diagnosis and prognostic evaluation. Experimental Design: Real-time quantitative PCR was done on a panel of prostate tissue isolated by laser capture microdissection. After generating antibodies against WDR19, tissue microarrays (TMA) were employed to compare WDR19 expression between normal, benign prostatic hyperplasia, and prostate cancer tissue. Results: Using microarrays and real-time quantitative PCR, we showed that WDR19 mRNA expression was increased in cancer. We further showed that WDR19 protein is localized to cytoplasmic subcellular granules and is expressed exclusively in prostate epithelia. Large-scale immunohistochemical staining using TMAs reveals a significant percentage of increase in intensely staining tissue cores in cancer tissue when compared with normal or benign prostatic hyperplastic tissue. Based on the analysis of a separate TMA for which clinical follow-up information was available, low-intensity WDR19 staining was significantly associated with decreased time to biochemical failure (P = 0.006) and with decreased time to locoregional recurrence (P = 0.050). Conclusions: WDR19 should be added to the list of prostate cancer tissue markers. The continued expansion of a multiple-marker panel will conceivably increase the sensitivity and specificity of prostate cancer diagnosis and prognosis.

GRK3 is essential for metastatic cells and promotes prostate tumor progression

Significance Although the majority of cancer-related deaths are consequences of metastatic dissemination, the molecular and cellular forces that drive tumor cell dispersion are still poorly understood. To help identify new regulators that play critical roles in these processes, we screened for human kinases that are important for continued survival of metastatic cells. One kinase identified from these screens, the G-protein–coupled receptor kinase 3 (GRK3; or β-adrenergic receptor kinase 2), was found to have a key role in promoting prostate tumor growth and metastasis in mouse models through enhancing angiogenesis. Notably, GRK3 is overexpressed in human prostate metastatic tumors. Further studies on GRK3 and its pathways promise to expand our knowledge of cancer metastasis and also yield new cancer therapeutic targets. The biochemical mechanisms that regulate the process of cancer metastasis are still poorly understood. Because kinases, and the signaling pathways they comprise, play key roles in regulation of many cellular processes, we used an unbiased RNAi in vitro screen and a focused cDNA in vivo screen against human kinases to identify those with previously undocumented roles in metastasis. We discovered that G-protein–coupled receptor kinase 3 (GRK3; or β-adrenergic receptor kinase 2) was not only necessary for survival and proliferation of metastatic cells, but also sufficient to promote primary prostate tumor growth and metastasis upon exogenous expression in poorly metastatic cells in mouse xenograft models. Mechanistically, we found that GRK3 stimulated angiogenesis, at least in part through down-regulation of thrombospondin-1 and plasminogen activator inhibitor type 2. Furthermore, GRK3 was found to be overexpressed in human prostate cancers, especially in metastatic tumors. Taken together, these data suggest that GRK3 plays an important role in prostate cancer progression and metastasis.

A positive real‐time elastography is an independent marker for detection of high‐risk prostate cancers in the primary biopsy setting

To evaluate the performance of real‐time elastography (RTE) in an initial biopsy setting.

Combination of real-time elastography and urine prostate cancer gene 3 (PCA3) detects more than 97% of significant prostate cancers

Abstract Objective. The prostate cancer gene 3 (PCA3) score in urine is a promising biomarker for prostate cancer. Real-time elastography (RTE) is a well-documented ultrasound modality. The objective of this study was to evaluate the ability to detect significant cancer foci in the prostate with these methods alone and in combination. Material and methods. From September 2009 to September 2010, 40 patients planned for radical prostatectomy underwent a PCA3 urine test and RTE before operation. A Hitachi EUB-8500 with prostate end-fire transrectal probe was used. The PCA3 score was evaluated with a standard cut-off value of 35. RTE was evaluated in correlation with whole-mount section pathology. Three patients fulfilled the criteria for insignificant prostate cancer and were excluded from the study. Results. The PCA3 score was increased in 26 patients (70%). RTE identified at least one tumour in 33 out of 37 patients (89%). RTE detected the largest tumour in 27 out of 37 patients (73%). More than one cancer was present in 29 patients and RTE identified more than one tumour in 13 of these. The RTE was false positive in four patients. The PCA3 score was increased in three out of four false-negative RTE patients. By combining both methods, 36 out of 37 patients (97%) with significant prostate cancer were detected. Conclusions.The combination of PCA3 score and RTE detected 97% of significant prostate cancers. The combinative use of RTE and PCA3 will be further investigated in an unselected series of men with suspected prostate cancer.