Immunoreactivity for prostate specific antigen and Ki67 differentiates subgroups of prostate cancer related to outcome.

Based on gene-expression profiles, prostate tumors can be subdivided into subtypes with different aggressiveness and response to treatment. We investigated if similar clinically relevant subgroups can be identified simply by the combination of two immunohistochemistry markers: one for tumor cell differentiation (prostate specific antigen, PSA) and one for proliferation (Ki67). This was analyzed in men with prostate cancer diagnosed at transurethral resection of the prostate 1975-1991 (n = 331) where the majority was managed by watchful waiting. Ki67 and PSA immunoreactivity was related to outcome and to tumor characteristics previously associated with prognosis. Increased Ki67 and decreased PSA were associated with poor outcome, and they provided independent prognostic information from Gleason score. A combinatory score for PSA and Ki67 immunoreactivity was produced using the median PSA and Ki67 levels as cut-off (for Ki67 the upper quartile was also evaluated) for differentiation into subgroups. Patients with PSA low/Ki67 high tumors showed higher Gleason score, more advanced tumor stage, and higher risk of prostate cancer death compared to other patients. Their tumor epithelial cells were often ERG positive and expressed higher levels of ErbB2, phosphorylated epidermal growth factor receptor (pEGF-R) and protein kinase B (pAkt), and their tumor stroma showed a reactive response with type 2 macrophage infiltration, high density of blood vessels and hyaluronic acid, and with reduced levels of caveolin-1, androgen receptors, and mast cells. In contrast, men with PSA high/Ki67 low tumors were characterized by low Gleason score, and the most favorable outcome amongst PSA/Ki67-defined subgroups. Men with PSA low/Ki67 low tumors showed clinical and tumor characteristics intermediate of the two groups above. A combinatory PSA/Ki67 immunoreactivity score identifies subgroups of prostate cancers with different epithelial and stroma phenotypes and highly different outcome but the clinical usefulness of this approach needs to be validated in other cohorts.

Prostate cancer induces C/EBPß expression in surrounding epithelial cells which relates to tumor aggressiveness and patient outcome.

BACKGROUND: Implantation of rat prostate cancer cells into the normal rat prostate results in tumor-stimulating adaptations in the tumor-bearing organ. Similar changes are seen in prostate cancer patients and they are related to outcome. One gene previously found to be upregulated in the non-malignant part of tumor-bearing prostate lobe in rats was the transcription factor CCAAT/enhancer-binding protein-ß (C/EBPß). METHODS: To explore this further, we examined C/EBPß expression by quantitative RT-PCR, immunohistochemistry, and Western blot in normal rat prostate tissue surrounding slow-growing non-metastatic Dunning G, rapidly growing poorly metastatic (AT-1), and rapidly growing highly metastatic (MatLyLu) rat prostate tumors-and also by immunohistochemistry in a tissue microarray (TMA) from prostate cancer patients managed by watchful waiting. RESULTS: In rats, C/EBPß mRNA expression was upregulated in the surrounding tumor-bearing prostate lobe. In tumors and in the surrounding non-malignant prostate tissue, C/EBPß was detected by immunohistochemistry in some epithelial cells and in infiltrating macrophages. The magnitude of glandular epithelial C/EBPß expression in the tumor-bearing prostates was associated with tumor size, distance to the tumor, and metastatic capacity. In prostate cancer patients, high expression of C/EBPß in glandular epithelial cells in the surrounding tumor-bearing tissue was associated with accumulation of M1 macrophages (iNOS+) and favorable outcome. High expression of C/EBPß in tumor epithelial cells was associated with high Gleason score, high tumor cell proliferation, metastases, and poor outcome. CONCLUSIONS: This study suggest that the expression of C/EBP-beta, a transcription factor mediating multiple biological effects, is differentially expressed both in the benign parts of the tumor-bearing prostate and in prostate tumors, and that alterations in this may be related to patient outcome.

High Caveolin-1 Expression in Tumor Stroma Is Associated with a Favourable Outcome in Prostate Cancer Patients Managed by Watchful Waiting.

In the present study we have investigated whether Caveolin-1 expression in non-malignant and malignant prostate tissue is a potential prognostic marker for outcome in prostate cancer patients managed by watchful waiting. Caveolin-1 was measured in prostate tissues obtained through transurethral resection of the prostate from 395 patients diagnosed with prostate cancer. The majority of the patients (n = 298) were followed by watchful waiting after diagnosis. Tissue microarrays constructed from malignant and non-malignant prostate tissue were stained with an antibody against Caveolin-1. The staining pattern was scored and related to clinicopathologic parameters and outcome. Microdissection and qRT-PCR analysis of Cav-1 was done of the prostate stroma from non-malignant tissue and stroma from Gleason 3 and 4 tumors. Cav-1 RNA expression was highest in non-malignant tissue and decreased during cancer progression. High expression of Caveolin-1 in tumor stroma was associated with significantly longer cancer specific survival in prostate cancer patients. This association remained significant when Gleason score and local tumor stage were combined with Caveolin-1 in a Cox regression model. High stromal Caveolin-1 immunoreactivity in prostate tumors is associated with a favourable prognosis in prostate cancer patients managed by watchful waiting. Caveolin-1 could possibly become a useful prognostic marker for prostate cancer patients that are potential candidates for active surveillance.

High Lysyl Oxidase (LOX) in the Non-Malignant Prostate Epithelium Predicts a Poor Outcome in Prostate Cancer Patient Managed by Watchful Waiting.

Lysyl oxidase (LOX) has been shown to both promote and suppress tumor progression, but its role in prostate cancer is largely unknown. LOX immunoreactivity was scored in prostate tumor epithelium, tumor stroma and in the tumor-adjacent non-malignant prostate epithelium and stroma. LOX scores in tumor and non-malignant prostate tissues were then examined for possible associations with clinical characteristics and survival in a historical cohort of men that were diagnosed with prostate cancer at transurethral resection and followed by watchful waiting. Men with a low LOX score in the non-malignant prostate epithelium had significantly longer cancer specific survival than men with a high score. Furthermore, LOX score in non-malignant prostate epithelium remained prognostic in a multivariable analysis including Gleason score. LOX score in prostate tumor epithelium positively correlated to Gleason score and metastases but was not associated with cancer survival. LOX score in tumor and non-malignant prostate stroma appeared unrelated to these tumor characteristics. In radical prostatectomy specimens, LOX immune-staining corresponded to LOX in-situ hybridization and LOX mRNA levels were found to be similar between tumor and adjacent non-malignant areas, but significantly increased in bone metastases samples. LOX levels both in tumors and in the surrounding tumor-bearing organ are apparently related to prostate cancer aggressiveness.

Morphological and morphometric characterization of direct transdifferentiation of support cells into hair cells in ototoxin-exposed neonatal utricular explants.

We have studied aminoglycoside-induced vestibular hair-cell renewal using long-term culture of utricular macula explants from 4-day-old rats. Explanted utricles were exposed to 1 mM of gentamicin for 48 h, during 2nd and 3rd days in vitro (DIV), and then recovering in unsupplemented medium. Utricles were harvested at specified time points from the 2nd through the 28th DIV. The cellular events that occurred within hair cell epithelia during the culture period were documented from serial sectioned specimens. Vestibular hair cells (HCs) and supporting cells (SCs) were systematically counted using light microscopy (LM) with the assistance of morphometric software. Ultrastructural observations were made from selected specimens with transmission electron microscopy (TEM). After 7 DIV, i.e. four days after gentamicin exposure, the density of HCs was 11% of the number of HCs observed in non-gentamicin-exposed control explants. At 28 DIV the HC density was 61% of the number of HCs observed in the control group explant specimens. Simultaneously with this increase in HCs there was a corresponding decline in the number of SCs within the epithelium. The proportion of HCs in relation to SCs increased significantly in the gentamicin-exposed explant group during the 5th to the 28th DIV period of culture. There were no significant differences in the volume estimations of the gentamicin-exposed and the control group explants during the observed period of culture. Morphological observations showed that gentamicin exposure induced extensive loss of HCs within the epithelial layer, which retained their intact apical and basal linings. At 7 to 14 DIV (i.e. 3-11 days after gentamicin exposure) a pseudostratified epithelium with multiple layers of disorganized cells was observed. At 21 DIV new HCs were observed that also possessed features resembling SCs. After 28 DIV a new luminal layer of HCs with several layers of SCs located more basally characterized the gentamicin-exposed epithelium. No mitoses were observed within the epithelial layer of any explants. Our conclusion is that direct transdifferentiation of SCs into HCs was the only process contributing to the renewal of HCs after gentamicin exposure in these explants of vestibular inner ear epithelia obtained from the labyrinths of 4-day-old rats.

ErbB2 receptor immunoreactivity in prostate cancer: relationship to the androgen receptor, disease severity at diagnosis and disease outcome.

BACKGROUND: ErbB2 is a member of the epidermal growth factor family of tyrosine kinases that is centrally involved in the pathogenesis of prostate cancer and several studies have reported that a high expression of this protein has prognostic value. In the present study, we have investigated whether tumour ErbB2 immunoreactivity (ErbB2-IR) has clinically useful prognostic value, i.e. that it provides additional prognostic information to that provided by routine clinical tests (Gleason score, tumour stage). METHODOLOGY/PRINCIPAL FINDINGS: ErbB2-IR was measured in a well-characterised tissue microarray of tumour and non-malignant samples obtained at diagnosis. Additionally, mRNA levels of ErbB2-IR in the prostate were determined in the rat following manipulation of circulating androgen levels. Tumour ErbB2-IR was significantly associated with the downstream signalling molecule phosphorylated-Akt and with the cell proliferation marker Ki-67. The significant association of tumour ErbB2-IR with the Gleason score at diagnosis was lost when controlled for the association of both parameters with Ki-67. In the rat prostate, mRNA for ErbB2 was inversely associated with circulating androgen levels. There was no association between ErbB2-IR and the androgen receptor (AR)-IR in the tumours, but an interaction between the two parameters was seen with respect to their association with the tumour stage. Tumour ErbB2-IR was confirmed to be a prognostic marker for disease-specific survival, but it did not provide significant additive information to the Gleason score or to Ki-67. CONCLUSIONS/SIGNIFICANCE: It is concluded that tumour ErbB2-IR is of limited clinical value as a prognostic marker to aid treatment decisions, but could be of pathophysiological importance in prostate cancer.

Potential upstream regulators of cannabinoid receptor 1 signaling in prostate cancer: a Bayesian network analysis of data from a tissue microarray.

BACKGROUND: The endocannabinoid system regulates cancer cell proliferation, and in prostate cancer a high cannabinoid CB1 receptor expression is associated with a poor prognosis. Down-stream mediators of CB1 receptor signaling in prostate cancer are known, but information on potential upstream regulators is lacking. RESULTS: Data from a well-characterized tumor tissue microarray were used for a Bayesian network analysis using the max-min hill-climbing method. In non-malignant tissue samples, a directionality of pEGFR (the phosphorylated form of the epidermal growth factor receptor) → CB1 receptors were found regardless as to whether the endocannabinoid metabolizing enzyme fatty acid amide hydrolase (FAAH) was included as a parameter. A similar result was found in the tumor tissue, but only when FAAH was included in the analysis. A second regulatory pathway, from the growth factor receptor ErbB2 → FAAH was also identified in the tumor samples. Transfection of AT1 prostate cancer cells with CB1 receptors induced a sensitivity to the growth-inhibiting effects of the CB receptor agonist CP55,940. The sensitivity was not dependent upon the level of receptor expression. Thus a high CB1 receptor expression alone does not drive the cells towards a survival phenotype in the presence of a CB receptor agonist. CONCLUSIONS: The data identify two potential regulators of the endocannabinoid system in prostate cancer and allow the construction of a model of a dysregulated endocannabinoid signaling network in this tumor. Further studies should be designed to test the veracity of the predictions of the network analysis in prostate cancer and other solid tumors.

Local and systemic protumorigenic effects of cancer-associated fibroblast-derived GDF15.

The tumor stroma is vital to tumor development, progression, and metastasis. Cancer-associated fibroblasts (CAF) are among the abundant cell types in the tumor stroma, but the range of their contributions to cancer pathogenicity has yet to be fully understood. Here, we report a critical role for upregulation of the TGFß/BMP family member GDF15 (MIC-1) in tumor stroma. GDF15 was found upregulated in situ and in primary cultures of CAF from prostate cancer. Ectopic expression of GDF15 in fibroblasts produced prominent paracrine effects on prostate cancer cell migration, invasion, and tumor growth. Notably, GDF15-expressing fibroblasts exerted systemic in vivo effects on the outgrowth of distant and otherwise indolent prostate cancer cells. Our findings identify tumor stromal cells as a novel source of GDF15 in human prostate cancer and illustrate a systemic mechanism of cancer progression driven by the tumor microenvironment. Further, they provide a functional basis to understand GDF15 as a biomarker of poor prognosis and a candidate therapeutic target in prostate cancer.

High density of S100A9 positive inflammatory cells in prostate cancer stroma is associated with poor outcome.

PURPOSE: To elucidate if the density of inflammatory cells expressing S100A9 in malignant and surrounding non-malignant prostate tissues is a prognostic marker for outcome in prostate cancer patients. EXPERIMENTAL DESIGN: Tissue was obtained from 358 men diagnosed with prostate cancer at transurethral resection of the prostate due to obstructive voiding problems, of which 260 were then followed with watchful waiting. Tissue microarrays of both malignant and non-malignant tissues were stained with an antibody against S100A9. The number of stained inflammatory cells was scored and related to clinical outcome and histopathological parameters of known prognostic value. RESULTS: A high number of inflammatory cells expressing S100A9 in both malignant and surrounding non-malignant tissues were associated with significantly shorter cancer-specific survival. This association remained significant when Gleason score and local tumour stage were analysed together with S100A9 in a Cox regression model. Low number of S100A9 positive cells in non-malignant stroma was correlated to significantly longer cancer-specific survival also in patients with Gleason score 8-10 tumours. S100A9 positive cells in tumour stroma were correlated with Gleason score, hyaluronan, platelet-derived growth factor receptor beta (PDGFR-ß), and androgen receptor (inverse correlation) in tumour stroma. S100A9 positive cells in non-malignant stroma correlated with androgen receptor in this tissue compartment (inverse correlation). CONCLUSIONS: A high number of S100A9 positive inflammatory cells in tumour stroma and in non-malignant stroma were associated with shorter cancer-specific survival in prostate cancer patients.

TMPRSS2-ERG expression predicts prostate cancer survival and associates with stromal biomarkers.

The TMPRSS2-ERG gene fusion is found in approximately half of all prostate cancers. The functional and prognostic significance of TMPRSS2-ERG is, however, not fully understood. Based on a historical watchful waiting cohort, an association between TMPRSS2-ERG, evaluated as positive immune staining, and shorter survival of prostate cancer patients was identified. Expression of ERG was also associated with clinical markers such as advanced tumor stage, high Gleason score, presence of metastasis and prognostic tumor cell markers such as high Ki67, pEGFR and pAkt. Novel associations between TMPRSS2-ERG and alterations in the tumor stroma, for example, increased vascular density, hyaluronan and PDGFRß and decreased Caveolin-1, all known to be associated with an aggressive disease, were found. The present study suggests that the TMPRSS2-ERG fusion gene is associated with a more aggressive prostate cancer phenotype, supported by changes in the tumor stroma.

Association between cannabinoid CB1 receptor expression and Akt signalling in prostate cancer.

BACKGROUND: In prostate cancer, tumour expression of cannabinoid CB1 receptors is associated with a poor prognosis. One explanation for this association comes from experiments with transfected astrocytoma cells, where a high CB receptor expression recruits the Akt signalling survival pathway. In the present study, we have investigated the association between CB1 receptor expression and the Akt pathway in a well-characterised prostate cancer tissue microarray. METHODOLOGY/PRINCIPAL FINDINGS: Phosphorylated Akt immunoreactivity (pAkt-IR) scores were available in the database. CB1 receptor immunoreactivity (CB1IR) was rescored from previously published data using the same scale as pAkt-IR. There was a highly significant correlation between CB1IR and pAkt-IR. Further, cases with high expression levels of both biomarkers were much more likely to have a more severe form of the disease at diagnosis than those with low expression levels. The two biomarkers had additive effects, rather than an interaction, upon disease-specific survival. CONCLUSIONS/SIGNIFICANCE: The present study provides data that is consistent with the hypothesis that at a high CB1 receptor expression, the Akt signalling pathway becomes operative.

Tumour epithelial expression levels of endocannabinoid markers modulate the value of endoglin-positive vascular density as a prognostic marker in prostate cancer.

Fatty acid amide hydrolase (FAAH) is responsible for the hydrolysis of the endogenous cannabinoid (CB) receptor ligand anandamide. Here we have investigated whether the expression levels of FAAH and CB1 receptors influence the prognostic value of markers of angiogenesis in prostate cancer. Data from a cohort of 419 patients who were diagnosed with prostate cancer at transurethral resection for lower urinary tract symptoms, of whom approximately 2/3 had been followed by expectancy, were used. Scores for the angiogenesis markers endoglin and von Willebrand factor (vWf), the endocannabinoid markers fatty acid amide hydrolase (FAAH) and cannabinoid CB1 receptors and the cell proliferation marker Ki-67 were available in the database. For the cases followed by expectancy, the prognostic value of endoglin was dependent upon the tumour epithelial FAAH immunoreactivity (FAAH-IR) and CB1IR scores, and the non-malignant epithelial FAAH-IR scores, but not the non-malignant CB1IR scores or the tumour blood vessel FAAH-IR scores. This dependency upon the tumour epithelial FAAH-IR or CB1IR scores was less apparent for vWf, and was not seen for Ki-67. Using an endoglin cut-off value of 10 positively stained vessels per core and a median split of tumour FAAH-IR, four groups could be generated, with 15year of disease-specific survival (%) of 68±7 (low endoglin, low FAAH), 45±11 (high endoglin, low FAAH), 77±6 (low endoglin, high FAAH) and 21±10 (high endoglin, high FAAH). Thus, the cases with high endoglin and high FAAH scores have the poorest rate of disease-specific survival. At diagnosis, the number of cases with tumour stages 1a-1b relative to stages 2-4 was sensitive to the endoglin score in a manner dependent upon the tumour FAAH-IR. It is concluded that the prognostic value of endoglin as a marker of neovascularisation in prostate cancer can be influenced by the expression level of markers of the endocannabinoid system. This article is part of a Special Issue entitled Lipid Metabolism in Cancer.

Phospho-Akt immunoreactivity in prostate cancer: relationship to disease severity and outcome, Ki67 and phosphorylated EGFR expression.

BACKGROUND: In the present study, we have investigated the prognostic usefulness of phosphorylated Akt immunoreactivity (pAkt-IR) in prostate cancer using a well-characterised tissue microarray from men who had undergone transurethral resection due to lower urinary tract symptoms. METHODOLOGY/PRINCIPAL FINDINGS: pAkt-IR in prostate epithelial and tumour cells was assessed using a monoclonal anti-pAkt (Ser(473)) antibody. Immunoreactive intensity was determined for 282 (tumour) and 240 (non-malignant tissue) cases. Tumour pAkt-IR scores correlated with Gleason score, tumour Ki67-IR (a marker of cell proliferation) and tumour phosphorylated epidermal growth factor receptor (pEGFR)-IR. For cases followed with expectancy, a high tumour pAkt-IR was associated with a poor disease-specific survival, and the prognostic information provided by this biomarker was additive to that provided by either (but not both) tumour pEFGR-IR or Ki67-IR. Upon division of the cases with respect to their Gleason scores, the prognostic value of pAkt-IR was seen for patients with Gleason score 8-10, but not for patients with Gleason score 6-7. CONCLUSIONS/SIGNIFICANCE: Tumour pAkt-IR is associated with both disease severity and disease-specific survival. However, its clinical use as a biomarker is limited, since it does not provide prognostic information in patients with Gleason scores 6-7.

Prostate cancer increases hyaluronan in surrounding nonmalignant stroma, and this response is associated with tumor growth and an unfavorable outcome.

Our objective was to investigate whether the presence of a tumor increases hyaluronan (HA) levels in surrounding prostate tissues and whether this extratumoral HA influences tumor growth and outcome. From a series of 287 men diagnosed with prostate cancer at transurethral resection and followed up with watchful waiting, tissue microarrays were constructed, stained, and scored for HA. A high HA staining score in the tumor stroma or in nonmalignant prostate tissue stroma were both associated positively with higher Gleason score and larger tumor volume, and was associated with a poor outcome. HA staining score was not an independent marker for outcome (multivariate Cox, with Gleason score, tumor volume, stage, and HA variables). In an orthotopic rat prostate cancer model, hyaluronic acid synthase-1 mRNA levels and HA staining were increased in normal prostate tissue surrounding prostate cancer. Orthotopic prostate cancer growth was increased by intraprostatic injection of HA. In conclusion, cancer in the prostate apparently stimulates HA synthesis both in tumor stroma and in the surrounding normal tissue. This promoted tumor growth and was associated with an unfavorable outcome.

LRIG1 and the liar paradox in prostate cancer: a study of the expression and clinical significance of LRIG1 in prostate cancer.

The course of prostate cancer varies greatly, and additional prognostic markers are needed. Leucine-rich repeats and immunoglobulin-like domains protein 1 (LRIG1) is an endogenous inhibitor of growth factor signaling and a proposed tumor suppressor. Publicly available gene expression datasets indicate that LRIG1 may be overexpressed in prostate cancer. In our study, the expression of LRIG1 protein in prostate cancer was evaluated for the first time. Immunohistochemistry was performed on tissue microarrays from two different patient series: 355 Swedish patients diagnosed by transurethral resection and 293 American patients who underwent radical prostatectomy. In the Swedish series, high expression of LRIG1 correlated with Gleason score, T-stage, tumor cell proliferation, vascular density and epidermal growth factor receptor (EGFR) phosphorylation. Among the 256 Swedish patients, followed by watchful waiting, high LRIG1 expression was significantly associated with short overall and prostate cancer-specific survival. In contrast, in the US series, high LRIG1 expression was significantly associated with long overall survival. In vitro cell experiments showed that LRIG1 was induced by androgen stimulation, and its expression inhibited prostate cancer cell proliferation. Thus, LRIG1 expression was an independent marker for poor survival in the untreated patient series, perhaps as a secondary marker of androgen receptor and/or EGFR activation. On the contrary, LRIG1 was a marker for good prognosis after prostatectomy, which might be due to its growth inhibiting properties. We propose that LRIG1 is an important determinant of prostate cancer growth, and the implications of its expression on patient outcome depend on the clinical and biological circumstances.

Tumor indicating normal tissue could be a new source of diagnostic and prognostic markers for prostate cancer.

IMPORTANCE OF THE FIELD: Prostate cancer is a common and multifocal disease but the diagnostic methods available are unsatisfactory. Most tumors present are of low malignant potential, whereas others are highly aggressive. At present, imaging cannot be used to guide tissue biopsies safely towards the most aggressive tumor present. To handle this problem multiple needle biopsies are taken. The biopsies often contain only normal prostate tissue, and even if the tumor is sampled it is not known whether a more aggressive cancer is present elsewhere in the organ. If changes in the normal tissue indicate the presence and nature of tumors, this information could be used to improve diagnostics and prognostics of prostate cancer. AREAS COVERED IN THIS REVIEW: Current evidence that the tumor-adjacent morphologically normal prostate tissue is not completely normal is reviewed, and that this tissue, named tumor indicating normal tissue (TINT) by the authors, can be used to diagnose prostate cancer. WHAT THE READER WILL GAIN: The reader will understand that tumors need to affect their surroundings in order to grow and metastasize and that the normal prostate tissue is therefore tinted by the presence and nature of cancer and that this knowledge can be used to develop new diagnostic and prognostic markers. TAKE HOME MESSAGE: TINT changes could probably, when more rigorously defined and validated, be used to diagnose and prognosticate prostate cancer.

Fatty acid amide hydrolase in prostate cancer: association with disease severity and outcome, CB1 receptor expression and regulation by IL-4.

BACKGROUND: Recent data have indicated that there may be a dysregulation of endocannabinoid metabolism in cancer. Here we have investigated the expression of the endocannabinoid metabolising enzyme fatty acid amide hydrolase (FAAH) in a well characterised tissue microarray from patients diagnosed with prostate cancer at transurethral resection for voiding problems. METHODOLOGY/PRINCIPAL FINDINGS: FAAH immunoreactivity (FAAH-IR) was assessed in formalin-fixed paraffin-embedded non-malignant and tumour cores from 412 patients with prostate cancer. CB(1) receptor immunoreactivity (CB(1)IR) scores were available for this dataset. FAAH-IR was seen in epithelial cells and blood vessel walls but not in the stroma. Tumour epithelial FAAH-IR was positively correlated with the disease severity at diagnosis (Gleason score, tumour stage, % of the specimen that contained tumour) for cases with mid-range CB(1)IR scores, but not for those with high CB(1)IR scores. For the 281 cases who only received palliative therapy at the end stages of the disease, a high tumour epithelial FAAH-IR was associated with a poor disease-specific survival. Multivariate Cox proportional-hazards regression analyses indicated that FAAH-IR gave additional prognostic information to that provided by CB(1)IR when a midrange, but not a high CB(1)IR cutoff value was used. Interleukin-4 (IL-4) receptor IR was found on tumour epithelial cells and incubation of prostate cancer PC-3 and R3327 AT1 cells with IL-4 increased their FAAH activity. CONCLUSIONS/SIGNIFICANCE: Tumour epithelial FAAH-IR is associated with prostate cancer severity and outcome at mid-range, but not high, CB(1)IR scores. The correlation with CB(1)IR in the tumour tissue may be related to a common local dysregulation by a component of the tumour microenvironment.

Mast cells are novel independent prognostic markers in prostate cancer and represent a target for therapy.

Mast cells affect growth in various human tumors, but their role in prostate cancer (PC) is unclear. Here, we identify mast cells as independent prognostic markers in PC using a large cohort of untreated PC patients with a long follow-up. By analyzing mast cells in different tissue compartments, our data indicate that intratumoral and peritumoral mast cells have anti- opposed to protumor properties. Intratumoral mast cells negatively regulate angiogenesis and tumor growth, whereas peritumoral mast cells stimulate the expansion of human prostate tumors. We also observed mast cell recruitment particularly to the peritumoral compartment in men during the formation of castrate-resistant prostate tumors. In our ortothopic rat model, mast cells accumulated in the peritumoral tissue where they enhanced angiogenesis and tumor growth. In line with this, prostate mast cells expressed high levels of the angiogenic factor FGF-2. Similar to the situation in men, mast cells infiltrated rat prostate tumors that relapsed after initially effective castration treatment, concurrent with a second wave of angiogenesis and an up-regulation of FGF-2. We conclude that mast cells are novel independent prognostic markers in PC and affect tumor progression in animals and patients. In addition, peritumoral mast cells provide FGF-2 to the tumor micro environment, which may contribute to their stimulating effect on angiogenesis.

Stromal PDGFRbeta expression in prostate tumors and non-malignant prostate tissue predicts prostate cancer survival.

BACKGROUND: The identification of new prognostic markers for prostate cancer is highly warranted, since it is difficult to identify patients requiring curative treatment. Data from both experimental models and clinical samples have identified important functions of PDGFRbeta on pericytes and fibroblasts in the tumor stroma. METHODOLOGY/PRINCIPAL FINDINGS: In this study the prognostic significance of PDGFRbeta in prostate cancer stroma, and in matched non-malignant tissue, was evaluated with immunohistochemistry. PDGFRbeta expression was analyzed in normal and tumor stroma from more than 300 prostate cancer patients. High PDGFRbeta expression in tumor stroma was associated with large tumor size, advanced stage, high Gleason score and high vessel density. Perivascular PDGFRbeta staining in tumors was also correlated with high Gleason score. Correlations were also observed between PDGFRbeta status in tumor stroma and non-malignant stroma. Similarly, high PDGFRbeta expression in adjacent non-malignant tissue stroma correlated with large tumor size, advanced stage, high Gleason score and proliferation in non-malignant epithelium. Interestingly, high levels of PDGFRbeta in the stroma of tumor and non-malignant tissue were associated with shorter cancer specific survival in prostate cancer patients. CONCLUSIONS/SIGNIFICANCE: The study revealed a number of novel associations between stromal PDGFRbeta expression in prostate tumors and several important clinical characteristics, including survival.

Low levels of phosphorylated epidermal growth factor receptor in nonmalignant and malignant prostate tissue predict favorable outcome in prostate cancer patients.

PURPOSE: To explore if the expression of phosphorylated epidermal growth factor receptor (pEGFR) in nonmalignant and malignant prostate tissue is a potential prognostic marker for outcome in prostate cancer patients. EXPERIMENTAL DESIGN: We used formalin-fixed tissues obtained through the transurethral resection of the prostate from 259 patients diagnosed with prostate cancer after the transurethral resection of the prostate, and patients were then followed with watchful waiting. Tissue microarrays of nonmalignant and malignant prostate tissue were stained with an antibody against pEGFR. The staining pattern was scored and related to clinicopathologic parameters and to outcome. RESULTS: Low phosphorylation of EGFR in prostate epithelial cells, both in the tumor and surprisingly also in the surrounding nonmalignant tissue, was associated with significantly longer cancer-specific survival in prostate cancer patients. This association remained significant when Gleason score and local tumor stage were added together with pEGFR to a Cox regression model. Tumor epithelial pEGFR immunoreactivity was significantly correlated to tumor cell proliferation, tumor vascular density, and nonmalignant epithelial pEGFR immunoreactivity. Patients with metastases had significantly higher immunoreactivity for tumor and nonmalignant epithelial pEGFR compared with patients without metastases. CONCLUSIONS: Low pEGFR immunoreactivity is associated with the favorable prognosis in prostate cancer patients and may provide information about which patients with Gleason score 6 and 7 tumors that will survive their disease even without treatment. Changes in the nonmalignant tissue adjacent to prostate tumors give prognostic information.