Strong EZH2 expression was associated with increased tumor cell proliferation in all four cancer types. Associations were also found between EZH2 and important clinicopathologic variables. EZH2 expression showed significant prognostic impact in melanoma, prostate, and endometrial carcinoma in univariate survival analyses, and revealed independent prognostic importance in carcinoma of the endometrium and prostate. CONCLUSION Our findings point at EZH2 as a novel and independent prognostic marker in endometrial cancer, and validate previous findings on prostate and breast cancer. Further, EZH2 expression was associated with features of aggressive cutaneous melanoma. The fact that EZH2 might identify increased tumor cell proliferation and aggressive subgroups in several cancers may be of practical interest because the polycomb group proteins have been suggested as candidates for targeted therapy. EZH2 expression should, therefore, be further examined as a possible predictive factor.

Purpose: Cell adhesion molecules are of crucial importance in cancer invasion and metastasis.Epithelial to mesenchymal transition, characterized by reduced E-cadherin and increased Ncadherin 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, h-catenin, and p120 CTN .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.

Metastatic tumors have been shown to establish permissive microenvironments for metastases via recruitment of bone marrow (BM)- derived cells. Here, we show that metastasis-incompetent tumors are also capable of generating such microenvironments. However, in these situations the otherwise pro-metastatic Gr1+ myeloid cells create a metastasis-refractory microenvironment via the induction of thrombospondin-1 (Tsp-1) by tumor-secreted prosaposin. (BM)-specific genetic deletion of Tsp-1 abolished the inhibition of metastasis, which was restored by BM transplant from Tsp-1+ donors. We also developed a 5-amino acid peptide from prosaposin as a pharmacological inducer of Tsp-1 in Gr1+ BM cells, which dramatically suppresses 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.

BackgroundIncreasing evidence implicates the critical roles of epigenetic regulation in cancer. Very recent reports indicate that global gene silencing in cancer is associated with specific epigenetic modifications. However, the relationship between epigenetic switches and more dynamic patterns of gene activation and repression has remained largely unknown.Methodology/Principal FindingsGenome-wide profiling of the trimethylation of histone H3 lysine 4 (H3K4me3) and lysine 27 (H3K27me3) was performed using chromatin immunoprecipitation coupled with whole genome promoter microarray (ChIP-chip) techniques. Comparison of the ChIP-chip data and microarray gene expression data revealed that loss and/or gain of H3K4me3 and/or H3K27me3 were strongly associated with differential gene expression, including microRNA expression, between prostate cancer and primary cells. The most common switches were gain or loss of H3K27me3 coupled with low effect on gene expression. The least prevalent switches were between H3K4me3 and H3K27me3 coupled with much higher fractions of activated and silenced genes. Promoter patterns of H3K4me3 and H3K27me3 corresponded strongly with coordinated expression changes of regulatory gene modules, such as HOX and microRNA genes, and structural gene modules, such as desmosome and gap junction genes. A number of epigenetically switched oncogenes and tumor suppressor genes were found overexpressed and underexpressed accordingly in prostate cancer cells.Conclusions/SignificanceThis work offers a dynamic picture of epigenetic switches in carcinogenesis and contributes to an overall understanding of coordinated regulation of gene expression in cancer. Our data indicate an H3K4me3/H3K27me3 epigenetic signature of prostate carcinogenesis.

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.

Nestin (neuroepithelial stem cell protein) is expressed in immature endothelial cells, and we here introduce coexpression of Nestin and Ki-67 as a novel angiogenesis marker on tissue sections. Including vascular endothelial growth factor (VEGF)-A and hypoxia-inducible factor-1A (HIF-1A) expression, we studied relation to disease progression in prostate cancer. Different patient series were included. Sections from 104 radical prostatectomies with long follow-up, 33 castration-resistant prostate cancers, 28 nonskeletal metastases, 13 skeletal metastases, and 41 benign prostatic hyperplasias were immunostained for Nestin/Ki-67, VEGF-A, and HIF-1A. Vascular proliferation by Nestin/Ki-67-positive vessels was counted within ''hotspot'' areas. Median vascular proliferation counts were 4-to 5-fold higher in castration-resistant prostate cancers and metastases versus localized cancers and prostatic hyperplasias (P < 0.0005). Among localized cancers, high vascular proliferation was significantly related to adverse clinicopathologic features and was a strong and independent predictor of biochemical failure (P < 0.005), clinical recurrence (P = 0.005), and skeletal metastasis (P = 0.025) in multivariate analysis. Castration-resistant cancers were characterized by reduced VEGF-A and increased HIF-1A expression, and vascular proliferation was associated with reduced patient survival in this group. Thus, vascular proliferation was of independent prognostic importance among prostate cancers. When compared with localized cancers, vascular proliferation was significantly increased in castration-resistant cases and metastatic lesions. The castration-resistant tumors exhibited weak VEGF-A but strong HIF-1A expression. These novel data might have an effect on clinical evaluation and treatment of prostate cancer patients. [Cancer Res 2009;69(11):4708-15]

Purpose: The human SIM2 gene is located within the Down's syndrome critical region of chromosome 21 and encodes transcription factors involved in brain development and neuronal differentiation. SIM2 has been assigned a possible role in the pathogenesis of solid tumors, and the SIM2-short isoform (SIM2-s) was recently proposed as a molecular target for cancer therapy. We previously reported SIM2 among the highly up-regulated genes in 29 prostate cancers, and the purpose of our present study was to examine the expression status of SIM2 at the transcriptional and protein level as related to outcome in prostate cancer. Experimental Design: By quantitative PCR, mRNA in situ hybridization, and immunohistochemistry, we evaluated the expression and significance of SIM2 isoforms in 39 patients with clinically localized prostate cancer and validated the expression of SIM2-s protein in an independent cohort of 103 radical prostatectomies from patients with long and complete follow-up. Results: The SIM2 isoforms (SIM2-s and SIM2-l) were significantly coexpressed and increased in prostate cancer. Tumor cell expression of SIM2-s protein was associated with adverse clinicopathologic factors like increased preoperative serum prostate-specific antigen, high histologic grade, invasive tumor growth with extra-prostatic extension, and increased tumor cell proliferation by Ki-67 expression. SIM2-s protein expression was significantly associated with reduced cancer-specific survival in multivariate analyses. Conclusions: These novel findings indicate for the first time that SIM2 expression might be important for clinical progress of human cancer and support the recent proposal of SIM2-s as a candidate for targeted therapy in prostate cancer.

The purpose of this study was to evaluate the ability of MR imaging with an endorectal coil (erMRI) to predict the local pathological stage of prostatic carcinoma prior to radical prostatectomy. Thirty-one consecutive patients (median age 61 years, range 40-71 years) with clinically localised prostate cancer were assessed preoperatively by endorectal MRI (at 1.0 T). The pulse sequences consisted of fast spin-echo axial and coronal T2-weighted images and inversion recovery with two echoes for axial fat-suppressed images. The assessment of tumour stage and measurement of tumour dimension by erMRI were compared with the corresponding findings on whole-mount step sections of the surgical specimens. Postoperatively, 14 of the 31 patients (45 %) were found to have extracapsular extension, 7 with capsular penetration (CP) only, and 7 had a combination of CP and seminal vesicle invasion (SVI). Capsular penetration was detected by erMRI with a sensitivity of 0.71 and specificity of 0.47, whereas the sensitivity for SVI detection was 0.71 and the specificity 0.83. Endorectal MRI for staging clinically localised prostatic carcinoma gives a good prediction of invasion of the seminal vesicles but is unreliable in predicting capsular penetration.