Cell Adhesion Molecules (CADMs) family comprise a newly identified protein family whose functions include cell polarity maintenance and tumor suppression. CADM-1, CADM-3 and CADM-4 have been shown to act as tumor suppressor genes in multiple cancers including prostate cancer. However, CADM-2 expression has not been determined in prostate cancer.
CADM-2 gene was cloned and characterized and its expression in human prostatic cell lines and cancer specimens was analyzed by RT-PCR and an immunohistochemical tissue array respectively. Effects of adenovirus-mediated CADM-2 expression on prostate cancer cells were also investigated. CADM-2 promoter methylation was evaluated by bisulfite sequencing and methylation-specific PCR (MSP).
We report the initial characterization of CADM-2 isoforms: CADM-2a and CADM-2b, each with separate promoters, in human chromosome 3p12.1. Prostate cancer cell lines LNCaP and DU145 expressed negligible CADM-2a relative to primary prostate tissue and cell lines RWPE-1 and PPC-1 while CADM-2b was maintained. Tissue array results from clinical specimens using immunohistochemistry demonstrated statistically significant decreased expression in prostate carcinoma compared to normal donor prostate, benign prostatic hyperplasia, prostatic intraepithelial neoplasia (PIN), and normal tissue adjacent to tumor (P<0.001). Adenovirus-mediated CADM-2a expression suppressed DU145 cell proliferation in vitro and colony formation in soft agar. The decrease in CADM-2a mRNA in cancer cell lines correlated with promoter region hypermethylation as determined by bisulfite sequencing and MSP. Accordingly, treatment of cells with the demethylating agent 5-aza-2′-deoxycytidine alone or in combination with the histone deacetylase inhibitor Trichostatin A resulted in reactivation of CADM-2a expression.
CADM-2 protein expression is significantly reduced in prostate cancer. Its expression is regulated in part by promoter methylation and implicates CADM-2 as a previously unrecognized tumor suppressor gene in a proportion of human prostate cancers.
CADM-2; prostate cancer; methylation; tumor suppressor
ELL-associated factor 2 (EAF2) is an androgen-responsive tumor suppressor frequently deleted in advanced prostate cancer that functions as a transcription elongation factor of RNA Pol II through interaction with the ELL family proteins. EAF2 knockout mice on a 129P2/OLA-C57BL/6J background developed late-onset lung adenocarcinoma, hepatocellular carcinoma, B-cell lymphoma and high-grade prostatic intraepithelial neoplasia. In order to further characterize the role of EAF2 in the development of prostatic defects, the effects of EAF2 loss were compared in different murine strains. In the current study, aged EAF2−/− mice on both the C57BL/6J and FVB/NJ backgrounds exhibited mPIN lesions as previously reported on a 129P2/OLA-C57BL/6J background. In contrast to the 129P2/OLA-C57BL/6J mixed genetic background, the mPIN lesions in C57BL/6J and FVB/NJ EAF2−/− mice were associated with stromal defects characteristic of a reactive stroma and a statistically significant increase in prostate microvessel density. Stromal inflammation and increased microvessel density was evident in EAF2-deficient mice on a pure C57BL/6J background at an early age and preceded the development of the histologic epithelial hyperplasia and neoplasia found in the prostates of older EAF2−/− animals. Mice deficient in EAF2 had an increased recovery rate and a decreased overall response to the effects of androgen deprivation. EAF2 expression in human cancer was significantly down-regulated and microvessel density was significantly increased compared to matched normal prostate tissue; furthermore EAF2 expression was negatively correlated with microvessel density. These results suggest that the EAF2 knockout mouse on the C57BL/6J and FVB/NJ genetic backgrounds provides a model of PIN lesions associated with an altered prostate microvasculature and reactive stromal compartment corresponding to that reported in human prostate tumors.
Histological evidence of pervasive inflammatory infiltrate has been noted in both benign prostatic hyperplasia/hypertrophy (BPH) and prostate cancer (PCa). Cytokines known to attract particular leukocyte subsets are secreted from prostatic stroma consequent to aging and also from malignant prostate epithelium. Therefore, we hypothesized that leukocytes associated with either acute or chronic inflammation attracted to the prostate consequent to aging or tumorigenesis may promote the abnormal cellular proliferation associated with BPH and PCa.
An in vitro system designed to mimic the human prostatic microenvironment incorporating prostatic stroma (primary and immortalized prostate stromal fibroblasts), epithelium (N15C6, BPH-1, LNCaP, and PC3 cells), and inflammatory infiltrate (HL-60 cells, HH, and Molt-3 T-lymphocytes) was developed. Modified Boyden chamber assays were used to test the ability of prostate stromal and epithelial cells to attract leukocytes and to test the effect of leukocytes on prostate cellular proliferation. Antibody arrays were used to identify leukocyte-secreted cytokines mediating prostate cellular proliferation.
Leukocytic cells migrated towards both prostate stromal and epithelial cells. CD4+ T-lymphocytes promoted the proliferation of both transformed and non-transformed prostate epithelial cell lines tested, whereas CD8+ T-lymphocytes as well as dHL-60M macrophagic and dHL-60N neutrophilic cells selectively promoted the proliferation of PCa cells.
The results of these studies show that inflammatory cells can be attracted to the prostate tissue microenvironment and can selectively promote the proliferation of non-transformed or transformed prostate epithelial cells, and are consistent with differential role(s) for inflammatory infiltrate in the etiologies of benign and malignant proliferative disease in the prostate.
BPH; PCa; immune; inflammatory infiltrate; chemokine; microenvironment
Expression of fibroblast growth factor 8 (FGF-8) is commonly increased in prostate cancer. Experimental studies have provided evidence that it plays a role in prostate tumorigenesis and tumor progression. To study how increased FGF-8 affects the prostate, we generated and analyzed transgenic (TG) mice expressing FGF-8b under the probasin promoter that targets expression to prostate epithelium. Prostates of the TG mice showed an increased size and changes in stromal and epithelialmorphology progressing fromatypia and prostatic intraepithelial neoplasia (mouse PIN, mPIN) lesions to tumors with highly variable phenotype bearing features of adenocarcinoma, carcinosarcoma, and sarcoma. The development of mPIN lesions was preceded by formation of activated stroma containing increased proportion of fibroblastic cells, rich vasculature, and inflammation. The association between advancing stromal and epithelial alterations was statistically significant. Microarray analysis and validation with quantitative polymerase chain reaction revealed that expression of osteopontin and connective tissue growth factor was markedly upregulated in TG mouse prostates compared with wild type prostates. Androgen receptor staining was decreased in transformed epithelium and in hypercellular stroma but strongly increased in the sarcoma-like lesions. In conclusion, our data demonstrate that disruption of FGF signaling pathways by increased epithelial production of FGF-8b leads to strongly activated and atypical stroma, which precedes development of mPIN lesions and prostate cancer with mixed features of adenocarcinoma and sarcoma in the prostates of TG mice. The results suggest that increased FGF-8 in human prostate may also contribute to prostate tumorigenesis by stromal activation.
Telomere attrition occurs early in the development of prostatic adenocarcinoma. However, little is known about either telomere status in benign prostatic hyperplasia (BPH), or the spatial and organ-wide distribution of potential telomere aberrations throughout all areas of prostatic glands affected by cancer or BPH.
Slot blot titration assay was used to determine telomere DNA content (TC), a proxy for telomere length, in macrodissected tissue consisting of 54 normal samples from 5 disease-free prostates, 128 BPH samples from 4 non-cancerous prostates, and 45 tumor, 73 BPH, and 4 prostatic intraepithelial neoplasia (PIN) samples from 5 cancerous prostates.
Compared to TC in normal prostate samples (n=54; TC mean=0.98), tumor samples displayed telomere attrition (n=45; TC mean=0.67). TC in PIN samples was similar to tumors. BPH samples from cancerous prostates were similar to TC in tumors and also displayed telomere shortening (n=73; TC mean=0.76), whereas BPH samples from non-cancerous prostates displayed longer telomeres (n=128; TC mean=1.06). In prostates affected by adenocarcinoma, areas of potential telomere attrition occurred in histologically normal tissues through the entire gland. However, three-dimensional zoning revealed a pattern of increasing TC as a function of distance from the primary (index) tumor.
Spatial distributions of TC in prostate specimens indicate a complex “field effect” with varying contributions from both cancer and BPH. The observation that telomere length variations occur in fields of histologically normal tissues surrounding the tumor is of clinical importance, as it may have implications for the diagnosis and focal therapy of prostate cancer.
Telomere alterations; prostate cancer; benign prostatic hyperplasia; field cancerization
SAM-pointed domain-containing ETS transcription factor (SPDEF) is expressed in normal prostate epithelium. While its expression changes during prostate carcinogenesis (PCa), the role of SPDEF in prostate cancer remains controversial due to the lack of genetic mouse models. In present study, we generated transgenic mice with the loss- or gain-of-function of SPDEF in prostate epithelium to demonstrate that SPDEF functions as tumor suppressor in prostate cancer. Loss of SPDEF increased cancer progression and tumor cell proliferation, whereas over-expression of SPDEF in prostate epithelium inhibited carcinogenesis and reduced tumor cell proliferation in vivo and in vitro. Transgenic over-expression of SPDEF inhibited mRNA and protein levels of Foxm1, a transcription factor critical for tumor cell proliferation, and reduced expression of Foxm1 target genes, including Cdc25b, Cyclin B1, Cyclin A2, Plk-1, AuroraB, CKS1 and Topo2alpha. Deletion of SPDEF in transgenic mice and cultures prostate tumor cells increased expression of Foxm1 and its target genes. Furthermore, an inverse correlation between SPDEF and Foxm1 levels was found in human prostate cancers. The two-gene signature of low SPDEF and high FoxM1 predicted poor survival in prostate cancer patients. Mechanistically, SPDEF bound to, and inhibited transcriptional activity of Foxm1 promoter by interfering with the ability of Foxm1 to activate its own promoter through auto-regulatory site located in the −745/−660 bp Foxm1 promoter region. Re-expression of Foxm1 restored cellular proliferation in the SPDEF-positive cancer cells and rescued progression of SPDEF-positive tumors in mouse prostates. Altogether, SPDEF inhibits prostate carcinogenesis by preventing Foxm1-regulated proliferation of prostate tumor cells. The present study identified novel crosstalk between SPDEF tumor suppressor and Foxm1 oncogene and demonstrated that this crosstalk is required for tumor cell proliferation during progression of prostate cancer in vivo.
Development of prostate cancer is a multistep process that involves the loss of tumor suppressor functions and activation of oncogenes. SPDEF transcription factor is expressed in normal prostate epithelium and its expression changes during prostate carcinogenesis (PCa). Since the role of SPDEF in PCa remains controversial, we generated transgenic mice with loss- and gain-of-function of SPDEF to demonstrate that SPDEF functions as a tumor suppressor in PCa. In animal models, the loss of SPDEF promoted PCa and increased the levels of Foxm1, a well-known oncogenic protein. Overexpression of SPDEF in prostate epithelium decreased PCa and reduced Foxm1 levels. Proliferation defects in SPDEF-containing tumor cells were corrected by re-expression of Foxm1, providing direct evidence that SPDEF inhibits tumor cell proliferation through Foxm1. We further showed that SPDEF directly bound to Foxm1 promoter and prevented its auto-regulatory activation. In prostate cancer patients, the low SPDEF and high Foxm1 were found in most aggressive prostate tumors that were associated with poor prognosis. The combined two-gene signature of low SPDEF and high Foxm1 was a strong predictor of survival in prostate cancer patients. The present study identified novel molecular mechanism of prostate cancer progression, providing a crosstalk between SPDEF tumor suppressor and Foxm1 oncogene.
Inflammatory processes are important components in the pathogenesis of many human cancers. According to the ‘injury and regeneration’ model for prostate carcinogenesis, injury caused by pathogens or pro-inflammatory cytotoxic agents would trigger proliferation of prostatic glandular cells, leading to the appearance of epithelial lesions named ‘Proliferative Inflammatory Atrophy’ (PIA). Inflammatory cells infiltrating the prostate would release genotoxic reactive oxygen species, leading atrophic cells to neoplastic progression. The hypothesis pointing to PIA as risk-lesion for prostate cancer has been extensively investigated at the cellular and molecular levels, but few morphological data are available linking PIA or prostatic intraepithelial neoplasia (PIN) to inflammation or clinical prostatitis. We investigated at the morphological level 1367 prostate biopsies from 98 patients with a recent history of chronic prostatitis, and 32 patients with biopsies positive for carcinoma. Our results show that i) PIA is found more frequently in biopsy cores containing a severe or moderate inflammatory focus, compared to NON-PIA lesions (partial or cystic atrophy); ii) the PIA lesion post-atrophic hyperplasia is more frequently found in tissues showing mild or no inflammation; iii) the extent of PIA per patient correlates with the burden of moderate or severe inflammation, whereas NON-PIA lesions do not; iv) low-grade PIN is in over 90% of cases emerging from normal, non-atrophic glands and is more frequently found in biopsy cores with absent or mild inflammatory burden; v) the inverse relationship between the prevalence of low-grade PIN and the extent of PIA lesions per patient is described by a power law function, suggesting the low likelihood of the concomitant presence of these lesions in the same tissue; vi) NON-PIA lesions correlate inversely with neoplasia in patients with prostate cancer; vii) the total scores of the NIH-CPSI questionnaire correlate with both PIA and inflammation burdens at diagnosis of prostatitis but not after pharmacological intervention. These results point to a positive association between tissue inflammation, clinical prostatitis and the putative cancer risk-lesion PIA, but do not support a model whereby low-grade PIN would arise from PIA.
proliferative inflammatory atrophy; prostate atrophy; prostate cancer; prostatitis; prostatic intraepithelial neoplasia; prostate; inflammation
Reciprocal interactions between epithelium and stroma play vital roles for prostate cancer development and progression. Enhanced secretions of cytokines and growth factors by cancer associated fibroblasts in prostate tumors create a favorable microenvironment for cancer cells to grow and metastasize. Our previous work showed that the progesterone receptor (PR) was expressed specifically in prostate stromal fibroblasts and smooth muscle cells. However, the expression levels of PR and its impact to tumor microenvironment in prostate tumors are poorly understood.
Immunohistochemistry assays are applied to human prostate tissue biopsies. Cell migration, invasion and proliferation assays are performed using human prostate cells. Real-time PCR and ELISA are applied to measure gene expression at molecular levels.
Immunohistochemistry assays showed that PR protein levels were decreased in cancer associated stroma when compared with paired normal prostate stroma. Using in vitro prostate stromal cell models, we showed that conditioned media collected from PR positive stromal cells inhibited prostate cancer cell migration and invasion, but had minor suppressive impacts on cancer cell proliferation. PR suppressed the secretion of stromal derived factor-1 (SDF-1) and interlukin-6 (IL-6) by stromal cells independent to PR ligands. Blocking PR expression by siRNA or supplementation of exogenous SDF-1 or IL-6 to conditioned media from PR positive stromal cells counteracted the inhibitory effects of PR to cancer cell migration and invasion.
Decreased expression of the PR in cancer associated stroma may contribute to the elevated SDF-1 and IL-6 levels in prostate tumors and enhance prostate tumor progression.
In our recent study, Periostin was up-regulated in prostate cancer(PCa) compared with benign prostate hyperplasia (BPH) by proteomics analysis of prostate biopsies. We investigated the effect of sliencing Periostin by RNA interference (RNAi) on the proliferation and migration of PCa LNCap cell line.
All the prostate biopsies from PCa, BPH and BPH with local prostatic intraepithelial neoplasm(PIN) were analyzed by iTRAQ(Isobaric tags for relative and absolute quantification) technology. Western blotting and immunohistochemical staining were used to verify Periostin expression in the tissues of PCa. Periostin expression in different PCa cell lines was determined by immunofluorescence staining, western blotting and reverse transcription PCR(RT-PCR). The LNCap cells with Periostin expression were used for transfecting shRNA-Periostin lentiviral particles. The efficancy of transfecting shRNA lentiviral particles was evaluated by immunofluorescence, western blotting and Real-time PCR. The effect of silencing Periostin expression by RNAi on proliferation of LNCap cells was determined by MTT assay and tumor xenografts. The tissue slices from theses xenografts were analyzed by hematoxylin and eosin(HE) staining. The expression of Periostin in the xenografts was deteminned by Immunohistochemical staining and western blotting. The migration of LNCap cells after silencing Periostin gene expression were analyzed in vitro.
Periostin as the protein of interest was shown 9.12 fold up-regulation in PCa compared with BPH. The overexpression of Periostin in the stroma of PCa was confirmed by western blotting and immunohistochemical staining. Periostin was only expressed in PCa LNCap cell line. Our results indicated that the transfection ratio was more than 90%. As was expected, both the protein level and mRNA level of Periostin in the stably expressing shRNA-Periostin LNCap cells were significantly reduced. The stably expressing shRNA-Periostin LNCap cells growed slowly in vitro and in vivo. The tissues of xenografts as PCa were verificated by HE staining. Additionally, the weak positive Periostin expressed tumor cells could be seen in the tissues of 6 xenografts from the group of down-regulated Periostin LNCap cells which had a significant decrease of the amount of Periostin compared to the other two group. Furthermore, our results demonstrated that sliencing Periostin could inhibit migration of LNCap cells in vitro.
Our data indicates that Periostin as an up-regulated protein in PCa may be a promising target of therapeutical intervention for PCa in future.
Periostin; Prostate cancer; RNAi; Proliferation; Migration
The incidence and mortality of prostate cancer (PCa) vary greatly in different geographic regions, for which lifestyle factors, such as dietary fat intake, have been implicated. Human 15-lipoxygenase-1 (h15-LO-1), which metabolizes polyunsaturated fatty acids, is a highly regulated, tissue-specific, lipid-peroxidating enzyme that functions in physiological membrane remodeling and in the pathogenesis of atherosclerosis, inflammation, and carcinogenesis. We have shown that aberrant overexpression of 15-LO-1 occurs in human PCa, particularly high-grade PCa, and in high-grade prostatic intraepithelial neoplasia (HGPIN), and that the murine orthologue is increased in SV40-based genetically engineered mouse (GEM) models of PCa, such as LADY and TRansgenic Adenocarcinoma of Mouse Prostate. To further define the role of 15-LO-1 in prostate carcinogenesis, we established a novel GEM model with targeted overexpression of h15-LO-1 in the prostate [human fifteen lipoxygenase-1 in mouse prostate (FLiMP)]. We used a Cre- mediated and a loxP-mediated recombination strategy to target h15-LO-1 specifically to the prostate of C57BL/6 mice. Wild-type (wt), FLiMP+/-, and FLiMP+/+ mice aged 7 to 21, 24 to 28, and 35 weeks were characterized by histopathology, immunohistochemistry (IHC), and DNA/RNA and enzyme analyses. Compared to wt mice, h15-LO-1 enzyme activity was increased similarly in both homozygous FLiMP+/+ and hemizygous FLiMP+/- prostates. Dorsolateral and ventral prostates of FLiMP mice showed focal and progressive epithelial hyperplasia with nuclear atypia, indicative of the definition of mouse prostatic intraepithelial neoplasia (mPIN) according to the National Cancer Institute. These foci showed increased proliferation by Ki-67 IHC. No progression to invasive PCa was noted up to 35 weeks. By IHC, h15-LO-1 expression was limited to luminal epithelial cells, with increased expression in mPIN foci (similar to human HGPIN). In summary, targeted overexpression of h15-LO-1 (a gene overexpressed in human PCa and HGPIN) to mouse prostate is sufficient to promote epithelial proliferation and mPIN development. These results support 15-LO-1 as having a role in prostate tumor initiation and as an early target for dietary or other prevention strategies. The FLiMP mouse model should also be useful in crosses with other GEM models to further define the combinations of molecular alterations necessary for PCa progression.
Transgenic; mouse model; genetically engineered mouse model; arachidonic acid; prostate cancer
The cancer cell microenvironment includes complex interactions between the cell and the extracellular matrix. Expression of the CCN family of extracellular matrix associated proteins is often modified in disease states. Depending on cancer type these changes are linked with enhanced or inhibited tumor growth. We characterized Cyr61 in prostate cancer. Cyr61 is an integrin binding matricellular protein with altered expression in many cancer types.
Materials and Methods
Cyr61 expression in prostate cancer, benign prostatic hyperplasia and normal tissues was evaluated by microarray analysis, quantitative real-time polymerase chain reaction and tissue microarray. Immunoblots were analyzed to assess endogenous protein expression in prostate cancer cell lines.
On genomic analysis Cyr61 up-regulation was observed in prostate cancer tissue and in normal prostate tissue adjacent to tumor vs that in prostate donor tissue. In 174 matched tumors and normal prostate tissues adjacent to tumor tissue microarray revealed significantly up-regulated Cyr61 protein expression in cancer tissue vs normal prostate tissue adjacent to tumor. Also, increased Cyr61 expression correlated with Gleason sum 8 or greater cancer. Staining in high grade prostatic intraepithelial neoplasia was moderately up-regulated vs that in normal prostate tissue adjacent to tumor but generally less intense than in carcinoma tissue.
In addition to the correlation with more advanced disease, the strong association between Cyr61 expression and prostate cancer supports the potential usefulness of Cyr61 as a novel biomarker for prostate cancer. This warrants further analysis to determine the mechanisms by which Cyr61 may contribute to prostate cancer development and progression.
prostate; prostatic neoplasms; cysteine-rich protein 61; biological markers; microarray analysis
Prostate stem cell antigen (PSCA) is a recently defined homologue of the Thy-1/Ly-6 family of glycosylphosphatidylinositol (GPI)-anchored cell surface antigens. The purpose of the present study was to examine the expression status of PSCA protein and mRNA in clinical specimens of human prostate cancer (Pca) and to validate it as a potential molecular target for diagnosis and treatment of Pca.
Materials and Methods
Immunohistochemical (IHC) and in situ hybridization (ISH) analyses of PSCA expression were simultaneously performed on paraffin-embedded sections from 20 benign prostatic hyperplasia (BPH), 20 prostatic intraepithelial neoplasm (PIN) and 48 prostate cancer (Pca) tissues, including 9 androgen-independent prostate cancers. The level of PSCA expression was semiquantitatively scored by assessing both the percentage and intensity of PSCA-positive staining cells in the specimens. Then compared PSCA expression between BPH, PIN and Pca tissues and analysed the correlations of PSCA expression level with pathological grade, clinical stage and progression to androgen-independence in Pca.
In BPH and low grade PIN, PSCA protein and mRNA staining were weak or negative and less intense and uniform than that seen in HGPIN and Pca. There were moderate to strong PSCA protein and mRNA expression in 8 of 11 (72.7%) HGPIN and in 40 of 48 (83.4%) Pca specimens examined by IHC and ISH analyses, with statistical significance compared with BPH (20%) and low grade PIN (22.2%) samples (p < 0.05, respectively). The expression level of PSCA increased with high Gleason grade, advanced stage and progression to androgen-independence (p < 0.05, respectively). In addition, IHC and ISH staining showed a high degree of correlation between PSCA protein and mRNA overexpression.
Our data demonstrate that PSCA as a new cell surface marker is overexpressed by a majority of human Pca. PSCA expression correlates positively with adverse tumor characteristics, such as increasing pathological grade (poor cell differentiation), worsening clinical stage and androgen-independence, and speculatively with prostate carcinogenesis. PSCA protein overexpression results from upregulated transcription of PSCA mRNA. PSCA may have prognostic utility and may be a promising molecular target for diagnosis and treatment of Pca.
Prostate; Neoplasm; Prostate stem cell antigen (PSCA)
The α6β4 integrin and its ligand, laminin-5, are essential gene products for the maintenance and remodeling of a stratified epithelium. Apparent loss of polarized α6β4 integrin and laminin-5 protein expression in invasive prostate cancer as compared to normal prostate glands is known to occur. It is unknown whether these alterations occur in prostatic intraepithelial neoplasia (PIN) lesions and whether this combined defect occurs in other epithelial cancers.
Human prostate tissues containing both normal, PIN, and cancerous regions and normal and cancer tissue from breast and colon were obtained at surgery and examined for β4 integrin and laminin-5 using standard immunofluorescence staining methods.
Both normal prostate glands and PIN lesions contain β4 integrin and laminin-5. Prostate carcinoma was unique in that both β4 integrin and laminin-5 expression was uniformly absent. In contrast, the β4 integrin and its ligand, laminin-5 were detected in all of the colon carcinoma cases and in 60% of the breast carcinomas.
The β4 integrin and its ligand, laminin-5 are altered during the transition of PIN lesions to invasive prostate carcinoma. These data suggest the loss of these proteins during cancer progression. In both prostate and breast carcinoma, the normal expression pattern of the β4 integrin and laminin-5 is interrupted, in contrast to the persistent β4 integrin and laminin-5 expression detected in colon carcinoma.
integrin; prostate; epithelial; laminin; carcinoma; α6β4; colon; breast; tissue
The ATBF1/ZFHX3 gene at 16q22 is the second most frequently mutated gene in human prostate cancer and has reduced expression or mislocalization in several types of human tumors. Nonetheless, the hypothesis that ATBF1 has a tumor suppressor function in prostate cancer has not been tested. In this study, we examined the role of ATBF1 in prostatic carcinogenesis by specifically deleting Atbf1 in mouse prostatic epithelial cells. We also examined the effect of Atbf1 deletion on gene expression and signaling pathways in mouse prostates. Histopathologic analyses showed that Atbf1 deficiency caused hyperplasia and mouse prostatic intraepithelial neoplasia (mPIN) primarily in the dorsal prostate but also in other lobes. Hemizygous deletion of Atbf1 also increased the development of hyperplasia and mPIN, indicating a haploinsufficiency of Atbf1. The mPIN lesions expressed luminal cell markers and harbored molecular changes similar to those in human PIN and prostate cancer, including weaker expression of basal cell marker cytokeratin 5 (Ck5), cell adhesion protein E-cadherin, and the smooth muscle layer marker Sma; elevated expression of the oncoproteins phospho-Erk1/2, phospho-Akt and Muc1; and aberrant protein glycosylation. Gene expression profiling revealed a large number of genes that were dysregulated by Atbf1 deletion, particularly those that encode for secretory and cell membrane proteins. The four signaling networks that were most affected by Atbf1 deletion included those centered on Erk1/2 and IGF1, Akt and FSH, NF-κB and progesterone and β-estradiol. These findings provide in vivo evidence that ATBF1 is a tumor suppressor in the prostate, suggest that loss of Atbf1 contributes to tumorigenesis by dysregulating membrane and secretory proteins and multiple signaling pathways, and provide a new animal model for prostate cancer.
Heparansulfate proteoglycans (HSPG) play an important role in cell–cell and cell–matrix interactions and signaling, and one of the key enzymes in heparansulfate biosynthesis is d-glucuronyl C5-epimerase (GLCE). A tumor suppressor function has been demonstrated for GLCE in breast and lung carcinogenesis; however, no data are available as to the expression and regulation of the gene in prostate cancer. In this study, decreased GLCE expression was observed in 10% of benign prostate hyperplasia (BPH) tissues and 53% of prostate tumors, and increased GLCE mRNA levels were detected in 49% of BPH tissues and 21% of tumors. Statistical analysis showed a positive correlation between increased GLCE expression and Gleason score, TNM staging, and prostate-specific antigen (PSA) level in the prostate tumors (Pearson correlation coefficients GLCE/Gleason = 0.56, P < 0.05; GLCE/TNM = 0.62, P < 0.05; and GLCE/PSA = 0.88, P < 0.01), suggesting GLCE as a candidate molecular marker for advanced prostate cancer. Immunohistochemical analysis revealed an intratumoral heterogeneity of GLCE protein levels both in BPH and prostate cancer cells, resulting in a mixed population of GLCE-expressing and nonexpressing epithelial cells in vivo. A model experiment on normal (PNT2) and prostate cancer (LNCaP, PC3, DU145) cell lines in vitro showed a 1.5- to 2.5-fold difference in GLCE expression levels between the cancer cell lines and an overall decrease in GLCE expression in cancer cells. Methyl-specific polymerase chain reaction (PCR), bisulfite sequencing, and deoxy-azacytidin (aza-dC) treatment identified differential GLCE promoter methylation (LNCaP 70–72%, PC3 32–35%, DU145, and PNT2 no methylation), which seems to contribute to heterogeneous GLCE expression in prostate tumors. The obtained results reveal the complex deregulation of GLCE expression in prostatic diseases compared with normal prostate tissue and suggest that GLCE may be used as a potential model to study the functional role of intratumor cell heterogeneity in prostate cancer progression.
The molecular mechanisms of intratumour heterogeneity of cancer cells, contributing to tissue malignisation, remain unclear. This study reveals the complex deregulation of d-glucuronyl C5-epimerase (GLCE) expression in benign prostatic hyperplasia and prostate tumours, and the high intratumour heterogeneity of prostate cancer cells in terms of GLCE expression and promoter methylation. The results suggest that GLCE may be used as a potential target gene to study the functional role of cancer cell heterogeneity in disease progression and treatment.
d-Glucuronyl C5-epimerase; expression; heparansulfate proteoglycan; heterogeneity; methylation; prostate cancer
15-Lipoxygenase 2 (15-LOX2), a lipid-peroxidizing enzyme, is mainly expressed in the luminal compartment of the normal human prostate and often decreased or lost in prostate cancer. Previous studies from our lab implicate 15-LOX2 as a functional tumor suppressor. To better understand the biological role of 15-LOX2 in vivo, we established prostate-specific 15-LOX2 transgenic mice using the ARR2PB promoter. Unexpectedly, transgenic expression of 15-LOX2 or 15-LOX2sv-b, a splice variant that lacks the arachidonic acid metabolizing activity, resulted in age-dependent prostatic hyperplasia and enlargement of the prostate. Prostatic hyperplasia induced by both 15-LOX2 and 15-LOX2sv-b was associated with an increase in luminal and Ki-67+ cells; however, 15-LOX2-transgenic prostates also showed a prominent increase in basal cells. Microarray analysis revealed distinct gene expression profiles that could help explain the prostate phenotypes. Strikingly, 15-LOX2, but not 15-LOX2sv-b, transgenic prostate showed upregulation of several well-known stem/progenitor cell molecules including Sca-1, Trop2, p63, Nkx3.1 and Psca. Prostatic hyperplasia caused by both 15-LOX2 and 15-LOX2sv-b did not progress to prostatic intraprostate neoplasia (PIN) or carcinoma and, mechanistically, prostate lobes (especially those of the 15-LOX2 mice) showed a dramatic increase in senescent cells as revealed by increased SA-βgal, p27Kip1 and HP1γ staining. Collectively, our results suggest that 15-LOX2 expression in mouse prostate leads to hyperplasia and also induces cell senescence, which may, in turn, function as a barrier to tumor development.
15-lipoxygenase 2; prostate; hyperplasia; senescence; tumor suppression; stem cells
Stromal–epithelial interaction is crucial to mediate normal prostate and prostate cancer (PCa) development. The indispensable roles of mesenchymal/stromal androgen receptor (AR) for the prostate organogenesis have been demonstrated by using tissue recombination from wild-type and testicular feminized mice. However, the stromal AR functions in the tumour microenvironment and the underlying mechanisms governing the interactions between the epithelium and stroma are not completely understood. Here, we have established the first animal model with AR deletion in stromal fibromuscular cells (dARKO, AR knockout in fibroblasts and smooth muscle cells) in the Pten+/− mouse model that can spontaneously develop prostatic intraepithelial neoplasia (PIN). We found that loss of stromal fibromuscular AR led to suppression of PIN lesion development with alleviation of epithelium proliferation and tumour-promoting microenvironments, including extracellular matrix (ECM) remodelling, immune cell infiltration and neovasculature formation due, in part, to the modulation of pro-inflammatory cytokines/chemokines. Finally, targeting stromal fibromuscular AR with the AR degradation enhancer, ASC-J9®, resulted in the reduction of PIN development/progression, which might provide a new approach to suppress PIN development.
androgen receptor; PIN; prostate stroma; PTEN; tumour microenvironment
Gene fusions prevalent in prostate cancer (CaP) lead to the elevated expression of the ERG proto-oncogene. ERG activation present in 50–70% of prostate tumors underscores one of the most common oncogenic alterations in CaP. Despite numerous reports of gene fusions and mRNA expression, ERG oncoprotein status in CaP still remains to be defined. Furthermore, development of ERG protein-based assays may provide a new dimension to evaluation of gene fusions involving diverse androgen-regulated promoters and the ERG protein-coding sequence. Through exhaustive evaluations of 132 whole-mount prostates (261 tumor foci and over 200 000 benign glands) for the ERG oncoprotein nuclear expression, we demonstrated 99.9% specificity for detecting prostate tumor cells using a highly specific anti-ERG monoclonal antibody. The ERG oncoprotein expression correlated well with fusion transcript or gene fusion in randomly selected specimens. Strong concordance of ERG-positive foci of prostatic intraepithelial neoplasia (PIN) with ERG-positive carcinoma (82 out of 85 sections with PIN, 96.5%) affirms the biological role of ERG in clonal selection of prostate tumors in 65% (86 out of 132) of patients. Conversely, ERG negative PINs were associated with ERG-negative carcinoma. Taken together, the homogeneous and strong ERG expression detected in individual tumors establishes the potential for ERG oncoprotein-based stratification of CaP.
ERG; oncoprotein; prostatic intraepithelial neoplasia; clonal selection; patient stratification
In this study was investigate IAPs in normal human prostate (NP), benign prostatic hyperplasia (BPH), prostatic intraepithelial neoplasia (PIN) and prostatic carcinoma (PC), and their involvement in apoptosis/proliferation via NF-kB (TNF-α, IL-1) stimulation.
Immunohistochemical and Western blot analyses were performed in 10 samples of normal prostates, 35 samples of BPH, 27 samples diagnosis of PIN (with low-grade PIN or high-grade PIN) and 95 samples of PC (with low, medium or high Gleason grades).
In NP, cytoplasm of epithelial cells were positive to c-IAP1/2 (80% of samples), c-IAP-2 (60%), ILP (20%), XIAP (20%); negative to NAIP and survivin. In BPH, epithelial cells were immunostained to c-IAP1/2 (57.57%), c-IAP-2 (57.57%), ILP (66.6%), NAIP (60.6%), XIAP (27.27%), survivin (9.1%). Whereas low-grade PIN showed intermediate results between NP and BPH; results in high-grade PIN were similar to those found in PC. In PC, epithelial cells were immunostained to c-IAP1/2, c-IAP-2, ILP, NAIP, XIAP (no Gleason variation) and survivin (increasing with Gleason).
IAPs could be involved in prostate disorder (BPH, PIN and PC) development since might be provoke inhibition of apoptosis and subsequently cell proliferation. At the same time, different transduction pathway such as IL-1/NIK/NF-kB or TNF/NF-kB (NIK or p38) also promotes proliferation. Inhibitions of IAPs, IL-1α and TNFα might be a possible target for PC treatment since IAPs are the proteins that inhibited apoptosis (favour proliferation) and IL-1α and TNFα would affect all the transduction pathway involucrate in the activation of transcription factors related to survival or proliferation (NF-kB, Elk-1 or ATF-2).
Bif-1 protein is a member of the endophilin B family that binds to and activates the pro-apoptotic Bax protein in response to apoptotic signals. Loss of Bif-1 suppresses the intrinsic pathway of apoptosis and promotes tumorigenesis. We examined the expression levels of Bif-1 protein in human prostate cancer.
Thirty-nine archival tissues specimens of human prostate cancer, and a human prostate cancer tissue microarray containing 19 samples of normal prostate (NR), 26 samples of benign prostatic hyperplasias (BPH), 30 samples of high grade prostatic intraepithelial neoplasia (PIN), and 153 samples of prostate cancer (CA), were selected for immuno-histochemical staining with Bif-1 antibody. The slides were scored by two independent observers.
Non TMA samples: moderate to strong Bif-1 staining was identified in 38 of 39 CA. In 32 cases foci of PIN were identified adjacent to CA. Of these, twenty-nine (91%) showed strong and diffuse Bif-1 staining. BPH, identified in 27 cases, was weakly Bif-1 positive in 89% of cases. TMA samples: 38.6% (59/153) of CA showed moderate-strong Bif-1 expression, and 21.5% (33/153) were Bif-1 negative. Bif-1 expression was moderate-strong in 76.6% (23/30) of PIN. Bif-1 was weak-moderate in 53.8% (14/26) of BPH and negative in 46.1% (12/26) of them. Low-moderate Bif-1 was seen in 89.5% of NR.
The loss of Bif-1 expression in a subset of CAs is in agreement with the proapoptotic function of Bif-1. The significance of the increased Bif-1 in a subgroup of CA and in PIN remains to be determined. It seems that Bif-1 has a role in prostate cancer, providing the rationale for using Bif-1 as a target for prostate anticancer therapy.
Bif-1; prostate adenocarcinoma; PIN; immunohistochemistry
Loss of the PTEN tumor suppressor is a common occurrence in human prostate cancer, particularly in advanced disease. In keeping with its role as a pivotal upstream regulator of the phosphatidylinositol 3-kinase signaling pathway, experimentally-induced deletion of Pten in the murine prostate invariably results in neoplasia. However, and unlike humans where prostate tumorigenesis likely evolves over decades, disease progression in the constitutively Pten deficient mouse prostate is relatively rapid, culminating in invasive cancer within several weeks post-puberty. Given that the prostate undergoes rapid androgen-dependent growth at puberty, and that Pten excisions during this time might be especially tumorigenic, we hypothesized that delaying prostate-specific Pten deletions until immediately after puberty might alter the pace of tumorigenesis. To this end we generated mice with a tamoxifen-inducible Cre recombinase transgene enabling temporal control over prostate-specific gene alterations. This line was then interbred with mice carrying floxed Pten alleles. Despite evidence of increased Akt/mTOR/S6K axis activity at early time points in Pten-deficient epithelial cells, excisions induced in the post-pubertal (6 wk-old) prostate yielded gradual acquisition of a range of lesions. These progressed from pre-malignant changes (nuclear atypia, focal hyperplasia) and low grade prostatic intraepithelial neoplasia (PIN) at 16–20 wks post-tamoxifen exposure, to overtly malignant lesions by ∼1 yr of age, characterized by high-grade PIN and microinvasive carcinoma. In contrast, when Pten excisions were triggered in the pre-pubertal (2 week-old) prostate, neoplasia evolved over a more abbreviated time-frame, with a spectrum of premalignant lesions, as well as overt PIN and microinvasive carcinoma by 10–12 wks post-tamoxifen exposure. These results indicate that the developmental stage at which Pten deletions are induced dictates the pace of PIN development.
Claudins are integral membrane proteins that are involved in forming cellular tight junctions. One member of the claudin family, claudin-3, has been shown to be overexpressed in breast, ovarian, and pancreatic cancer. Here we use immunohistochemistry to evaluate its expression in benign prostatic hyperplasia (BPH), prostatic intraepithelial neoplasia (PIN), normal tissue adjacent to prostatic adenocarcinoma (NAC), primary prostatic adenocarcinoma (PCa), and metastatic prostatic adenocarcinoma (Mets).
Tissue microarrays were immunohistochemically stained for claudin-3, with the staining intensities subsequently quantified and statistically analyzed using a one-way ANOVA with subsequent Tukey tests for multiple comparisons or a nonparametric equivalent. Fifty-three cases of NAC, 17 cases of BPH, 35 cases of PIN, 107 cases of PCa, and 55 cases of Mets were analyzed in the microarrays.
PCa and Mets had the highest absolute staining for claudin-3. Both had significantly higher staining than BPH (p < 0.05 in both cases) and NAC (p < 0.05 in both cases). PIN had a lower, but non-significant, staining score than PCa and Mets, but a statistically higher score than both BPH and NAC (p < 0.05 for both cases). No significant differences were observed between PCa, Mets, and PIN.
To our knowledge, this represents one of the first studies comparing the immunohistochemical profiles of claudin-3 in PCa and NAC to specimens of PIN, BPH, and Mets. These findings provide further evidence that claudin-3 may serve as an important biomarker for prostate cancer, both primary and metastatic, but does not provide evidence that claudin-3 can be used to predict risk of metastasis.
Although the amplified-in-breast cancer 1 (AIB1, SRC-3, ACTR or NCoA3) was defined as a coactivator for androgen receptor (AR) by in vitro studies, its role in AR-mediated prostate development and prostate cancer remained unexplored. We report here that AIB1 is expressed in the basal and stromal cells, but not in the epithelial cells of the normal mouse prostates. AIB1 deficiency only slightly delayed prostate growth and had no effect on androgen-dependent prostate regeneration, suggesting an unessential role of AIB1 in AR function in the prostate. Surprisingly, when prostate tumorigenesis was induced by the SV40 transgene in TRAMP mice, AIB1 expression was observed in certain epithelial cells of the prostate intraepithelial neoplasia (PIN) and well-differentiated carcinoma (WDC) and in almost all cells of the poorly differentiated carcinoma (PDC). After AIB1 was genetically inactivated in AIB1−/−/TRAMP mice, the progression of prostate tumorigenesis in most AIB1−/−/TRAMP mice was arrested at the WDC stage. WT/TRAMP mice developed progressive, multi-focal and metastatic prostate tumors and died between 25–34 weeks. In contrast, AIB1−/−/TRAMP mice only exhibited PIN and early stage WDC by 39 weeks. AIB1−/−/TRAMP prostates showed much lower cell proliferation than WT/TRAMP prostates. Most AIB1−/−/TRAMP mice could survive more than 35 weeks and died with other types of tumors or unknown reasons. Our results indicate that induction of AIB1 expression in partially transformed epithelial cells is essential for progression of prostate tumorigenesis into PDC. Inhibition of AIB1 expression or function in the prostate epithelium may be a potential strategy to suppress prostate cancer initiation and progression.
AIB1; SRC-3; overexpression; prostate cancer; tumor progression; TRAMP
Aldo-keto reductase family 1 member C3 (AKR1C3) is a key steroidogenic enzyme that is overexpressed in prostate cancer (PCa) and is associated with the development of castration-resistant prostate cancer (CRPC). The aim of this study was to investigate the correlation between the expression level of AKR1C3 and the progression of PCa.
Sixty human prostate needle biopsy tissue specimens and ten LNCaP xenografts from intact or castrated male mice were included in the study. The relationship between the level of AKR1C3 expression by immunohistochemistry and evaluation factors for PCa progression, including prostate-specific antigen (PSA), Gleason score (GS) and age, were analyzed.
Low immunoreactivity of AKR1C3 was detected in normal prostate epithelium, benign prostatic hyperplasia (BPH) and prostatic intraepithelial neoplasia (PIN). Positive staining was gradually increased with an elevated GS in PCa epithelium and LNCaP xenografts in mice after castration. The Spearman’s r values (rs) of AKR1C3 to GS and PSA levels were 0.396 (P = 0.025) and -0.377 (P = 0.036), respectively, in PCa biopsies. The rs of AKR1C3 to age was 0.76 (P = 0.011). No statistically significant difference was found with other variables.
Our study suggests that the level of AKR.
1C3 expression is positively correlated with an elevated GS, indicating that AKR1C3 can serve as a promising biomarker for the progression of PCa.
The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/7748245591110149.
AKR1C3; Prostate cancer; Gleason score; PSA; Biomarker
Prostatic carcinoma is a common and growing public health problem. Histological evaluation is fairly adequate for assessing tumor differentiation, but tumor proliferative activity is difficult to measure. Increasing evidence suggests that the factors controlling cell cycle progression also modulate the rate of ribosome biogenesis. Despite the influence of cyclin D1 and argyrophilic nuclear organizer region (AgNOR) on prostate cancer proliferation, few studies have evaluated the diagnostic importance of these markers. Therefore, the present study was carried out to analyze the diagnostic value of the proliferative markers cyclin D1 and AgNOR in various prostatic lesions and to determine whether any association or relation between these markers and different Gleason grades exists.
A total 50 cases of various prostatic lesions were studied. Tumor grade, AgNOR staining, and cyclin D1 expression were evaluated in all cases. Correlations between the intensity and differential localization of these markers and Gleason grades were evaluated.
The mean AgNOR count in cases of prostatic intraepithelial neoplasia was high compared with cases of benign prostatic hyperplasia (BPH) but lower than that of carcinoma cases. The intensity of cyclin D1 expression was high in carcinoma. A total of 14 cases (46.67%) showed strong positivity. No significant correlation was found between the intensity of cyclin D1 expression, AgNOR count, and histologic grades of prostatic carcinoma, whereas a significant correlation was observed between intensity and percentage expression of cyclin D1 in BPH and carcinoma (P<0.01). Nuclear as well as cytoplasmic positivity was seen among various grades of carcinoma.
AgNOR count and cyclin D1 may be helpful in distinguishing between BPH and carcinoma of the prostate but may not be used as reliable indicators of the grade of prostatic adenocarcinoma because of overlapping values in various grades. However, further studies on larger samples are required to elucidate the role of these markers in identification of premalignant lesions.
Prostate; Carcinoma; Prostatic hyperplasia; Cyclin D1; AgNORs; Immunohistochemistry