Clinical and biomarker correlates of androgen-independent, locally aggressive prostate cancer with limited metastatic potential

The Role of the Metzincin Superfamily in Prostate Cancer Progression: A Systematic-Like Review

Prostate cancer remains a leading cause of cancer-related morbidity in men. Potentially important regulators of prostate cancer progression are members of the metzincin superfamily of proteases, principally through their regulation of the extracellular matrix. It is therefore timely to review the role of the metzincin superfamily in prostate cancer and its progression to better understand their involvement in this disease. A systematic-like search strategy was conducted. Articles that investigated the roles of members of the metzincin superfamily and their key regulators in prostate cancer were included. The extracted articles were synthesized and data presented in tabular and narrative forms. Two hundred and five studies met the inclusion criteria. Of these, 138 investigated the role of the Matrix Metalloproteinase (MMP) subgroup, 34 the Membrane-Tethered Matrix Metalloproteinase (MT-MMP) subgroup, 22 the A Disintegrin and Metalloproteinase (ADAM) subgroup, 8 the A Disintegrin and Metalloproteinase with Thrombospondin Motifs (ADAMTS) subgroup and 53 the Tissue Inhibitor of Metalloproteinases (TIMP) family of regulators, noting that several studies investigated multiple family members. There was clear evidence that specific members of the metzincin superfamily are involved in prostate cancer progression, which can be either in a positive or negative manner. However, further understanding of their mechanisms of action and how they may be used as prognostic indicators or molecular targets is required.

Age, Gleason Score, and PSA are important prognostic factors for survival in metastatic castration-resistant prostate cancer. Results of The Uroncor Group (Uro-Oncological Tumors) of the Spanish Society of Radiation Oncology (SEOR)

INTRODUCTION

The treatment of metastatic castration-resistant prostate cancer (mCRPC) has changed significantly in recent years. Inhibitors of androgen receptors have shown especially significant benefits in overall (OS) and progression-free survival (PFS), with a good toxicity profile. Treatment selection depends on the patient's individual clinical, radiological, and biological characteristics.

OBJECTIVE

To describe treatment outcomes (efficacy, toxicity) in a cohort of patients with mCRPC in Spain.

MATERIALS AND METHODS

Multicenter, retrospective study of patients with mCRPC included in a database of the Urological Tumour Working Group (URONCOR) of the Spanish Society of Radiation Oncology (SEOR). Metastatic CRPC was defined according to the prostate cancer working group 3 (PCWG3) criteria. The Kaplan-Meier technique was used to evaluate OS and the Common Terminology Criteria for Adverse Events (CTCAE, v.4.0) were used to assess toxicity. Univariate and multivariate Cox regression analyses were performed to identify the factors significantly associated with OS.

RESULTS

A total of 314 patients from 17 hospitals in Spain diagnosed with mCRPC between June 2010 and September 2017 were included in this study. Mean age at diagnosis was 68 years (range 45-89). At a median follow-up of 35 months, OS at 1, 3, and 5 years were 92%, 38%, and 28%, respectively. Grades 1-2 and grade 3 toxicity rates were, respectively, 68% and 19%. No grade 4 toxicities were observed. On the multivariate analysis, the following factors were significantly associated with OS: age (hazard ratio [HR] 0.42, p = 0.010), PSA value at diagnosis of mCRPC (HR 0.55, p = 0.008), and Gleason score (HR 0.61, p = 0.009).

CONCLUSIONS

Age, Gleason score, and PSA at diagnosis of mCRPC are independently associated with overall survival in patients with mCRPC. The efficacy and toxicity outcomes in this patient cohort treated in radiation oncology departments in Spain are consistent with previous reports.

A Hierarchical Machine Learning Model to Discover Gleason Grade-Specific Biomarkers in Prostate Cancer

(1) Background:One of the most common cancers that affect North American men and men worldwide is prostate cancer. The Gleason score is a pathological grading system to examine the potential aggressiveness of the disease in the prostate tissue. Advancements in computing and next-generation sequencing technology now allow us to study the genomic profiles of patients in association with their different Gleason scores more accurately and effectively. (2) Methods: In this study, we used a novel machine learning method to analyse gene expression of prostate tumours with different Gleason scores, and identify potential genetic biomarkers for each Gleason group. We obtained a publicly-available RNA-Seq dataset of a cohort of 104 prostate cancer patients from the National Center for Biotechnology Information's (NCBI) Gene Expression Omnibus (GEO) repository, and categorised patients based on their Gleason scores to create a hierarchy of disease progression. A hierarchical model with standard classifiers in different Gleason groups, also known as nodes, was developed to identify and predict nodes based on their mRNA or gene expression. In each node, patient samples were analysed via class imbalance and hybrid feature selection techniques to build the prediction model. The outcome from analysis of each node was a set of genes that could differentiate each Gleason group from the remaining groups. To validate the proposed method, the set of identified genes were used to classify a second dataset of 499 prostate cancer patients collected from cBioportal. (3) Results: The overall accuracy of applying this novel method to the first dataset was 93.3%; the method was further validated to have 87% accuracy using the second dataset. This method also identified genes that were not previously reported as potential biomarkers for specific Gleason groups. In particular, PIAS3 was identified as a potential biomarker for Gleason score 4 + 3 = 7, and UBE2V2 for Gleason score 6. (4) Insight: Previous reports show that the genes predicted by this newly proposed method strongly correlate with prostate cancer development and progression. Furthermore, pathway analysis shows that both PIAS3 and UBE2V2 share similar protein interaction pathways, the JAK/STAT signaling process.

Expression of β-catenin and mesenchymal markers in canine prostatic hyperplasia and carcinoma

β-catenin is a nuclear signalling molecule that is associated with human prostatic neoplasia and the epithelial-mesenchymal transition (EMT) process. The present study evaluates immunohistochemically the expression of β-catenin and the mesenchymal markers vimentin, desmin, calponin and smooth muscle actin (SMA) in four normal canine prostates and prostate samples from 15 dogs with benign prostatic hyperplasia (BPH) and six with prostatic carcinoma (PC). β-catenin was located on the membrane of normal epithelial cells, while the same marker had both cytoplasmic and membrane expression in hyperplastic cells and a nuclear redistribution in PC. Vimentin-positive luminal cells were observed in two of the 15 cases of BPH and in all PC samples, suggesting the conversion of neoplastic epithelial cells to a mesenchymal type. SMA was consistently negative in PC, but there was mild desmin and calponin immunoreactivity in these lesions. As in men, β-catenin is involved in canine prostatic carcinogenesis, thus further validating the use of this animal model to study human prostatic disease.

Primary cilia are lost in preinvasive and invasive prostate cancer

Prostate cancer is the second most commonly diagnosed cancer in men worldwide. Little is known about the role of primary cilia in preinvasive and invasive prostate cancer. However, reduced cilia expression has been observed in human cancers including pancreatic cancer, renal cell carcinoma, breast cancer, cholangiocarcinoma, and melanoma. The aim of this study was to characterize primary cilia expression in preinvasive and invasive human prostate cancer, and to investigate the correlation between primary cilia and the Wnt signaling pathway. Human prostate tissues representative of stages of prostate cancer formation (normal prostate, prostatic intraepithelial neoplasia (PIN), and invasive prostate cancer (including perineural invasion)) were stained for ciliary proteins. The frequency of primary cilia was determined. A decrease in the percentage of ciliated cells in PIN, invasive cancer and perineural invasion lesions was observed when compared to normal. Cilia lengths were also measured to indirectly test functionality. Cilia were shorter in PIN, cancer, and perineural invasion lesions, suggesting dysfunction. Primary cilia have been shown to suppress the Wnt pathway. Increased Wnt signaling has been implicated in prostate cancer. Therefore, we investigated a correlation between loss of primary cilia and increased Wnt signaling in normal prostate and in preinvasive and invasive prostate cancer. To investigate Wnt signaling in our cohort, serial tissue sections were stained for β-catenin as a measure of Wnt signaling. Nuclear β-catenin was analyzed and Wnt signaling was found to be higher in un-ciliated cells in the normal prostate, PIN, a subset of invasive cancers, and perineural invasion. Our results suggest that cilia normally function to suppress the Wnt signaling pathway in epithelial cells and that cilia loss may play a role in increased Wnt signaling in some prostate cancers. These results suggest that cilia are dysfunctional in human prostate cancer, and increase Wnt signaling occurs in a subset of cancers.

Interaction between the TP63 and SHH pathways is an important determinant of epidermal homeostasis

Deregulation of the hedgehog (HH) pathway results in overexpression of the GLI target BCL2 and is an initiating event in specific tumor types including basal cell carcinoma of the skin. Regulation of the HH pathway during keratinocyte differentiation is not well understood. We measured HH pathway activity in response to differentiation stimuli in keratinocytes. An upregulation of suppressor of fused (SUFU), a negative regulator of the HH pathway, lowered HH pathway activity and was accompanied by loss of BCL2 expression associated with keratinocyte differentiation. We used in vitro and in vivo models to demonstrate that ΔNp63α, a crucial regulator of epidermal development, activates SUFU transcription in keratinocytes. Increasing SUFU protein levels inhibited GLI-mediated gene activation in suprabasal keratinocytes and promoted differentiation. Loss of SUFU expression caused deregulation of keratinocyte differentiation and BCL2 overexpression. Using in vivo murine models, we also provide evidence of GLI-mediated regulation of the TP63 pathway. p63 expression appears essential to establish an optimally functioning HH pathway. These observations present a regulatory mechanism by which SUFU acts as an interacting node between the HH and TP63 pathways to mediate differentiation and maintain epidermal homeostasis. Disruption of this regulatory node can be an important contributor to multistep carcinogenesis.

Diagnostic and prognostic role of matrix metalloproteases in cancer

BACKGROUND

Matrix metalloproteases (MMPs) are key players in the progression and metastasis of cancer. MMPs cleave extracellular matrix components and in this way promote tumor growth, invasion and vascularization. MMPs also affect tumor progression by regulating availability and activity of growth factors, inflammatory cytokines and chemokines. Accordingly, several MMPs have been found to serve as prognostic indicators in solid tumors. Usually the increased levels of MMPs in patients' tumor tissue or serum/plasma are associated with poor outcome. Interestingly, recent results show that certain MMPs also serve as tumor suppressors.

OBJECTIVE

This review discusses the latest view on MMPs as diagnostic and prognostic indicators in cancer patients.

METHODS

Studies with clinical samples of 70 or more patients are included in particular. In addition, the possible roles of MMPs in future molecular diagnostics and in the evaluation of therapeutic responses are discussed.

CONCLUSION

MMP-9 in particular has shown prognostic value in various types of tumor, and its measurement in circulation, urine or tumor tissue might help in clinical surveillance of otherwise problematic patient cases. There is upcoming new knowledge on MMPs in therapy response evaluation, in which MMPs might be useful together with CT scans and other clinically more established prognostic factors. Certain MMPs have a dual role in terms of cancer-modulating properties and thus it is essential to evaluate their expression and function in tumor cells and host environment to select validated therapy targets but spare MMP antitargets.

LNCaP Atlas: gene expression associated with in vivo progression to castration-recurrent prostate cancer

Background

There is no cure for castration-recurrent prostate cancer (CRPC) and the mechanisms underlying this stage of the disease are unknown.

Methods

We analyzed the transcriptome of human LNCaP prostate cancer cells as they progress to CRPC in vivo using replicate LongSAGE libraries. We refer to these libraries as the LNCaP atlas and compared these gene expression profiles with current suggested models of CRPC.

Results

Three million tags were sequenced using in vivo samples at various stages of hormonal progression to reveal 96 novel genes differentially expressed in CRPC. Thirty-one genes encode proteins that are either secreted or are located at the plasma membrane, 21 genes changed levels of expression in response to androgen, and 8 genes have enriched expression in the prostate. Expression of 26, 6, 12, and 15 genes have previously been linked to prostate cancer, Gleason grade, progression, and metastasis, respectively. Expression profiles of genes in CRPC support a role for the transcriptional activity of the androgen receptor (CCNH, CUEDC2, FLNA, PSMA7), steroid synthesis and metabolism (DHCR24, DHRS7, ELOVL5, HSD17B4, OPRK1), neuroendocrine (ENO2, MAOA, OPRK1, S100A10, TRPM8), and proliferation (GAS5, GNB2L1, MT-ND3, NKX3-1, PCGEM1, PTGFR, STEAP1, TMEM30A), but neither supported nor discounted a role for cell survival genes.

Conclusions

The in vivo gene expression atlas for LNCaP was sequenced and support a role for the androgen receptor in CRPC.

N-terminal truncation of Stat5a/b circumvents PIAS3-mediated transcriptional inhibition of Stat5 in prostate cancer cells

Transcription factor Stat5a/b is critical for prostate cancer cell survival and for prostate xenograft tumor growth. In addition, the Stat5a/b signaling pathway may contribute to progression of organ-confined prostate cancer to castration-resistant and/or metastatic disease. Expression of nuclear Stat5a/b is clustered to high grade human prostate cancers, and nuclear Stat5a/b in primary prostate cancer predicts early disease recurrence after initial treatment. Here, we show by Western blotting and electromobility shift assay that Stat5a/b protein in human prostate cancer is N-terminally truncated. This short form of Stat5a/b is generated post-translationally in vivo in prostate cancer cells and is the predominant form of Stat5a/b that binds to DNA. We further demonstrate by mutagenesis and co-immunoprecipitations that the N-domain of Stat5a/b is required for binding to PIAS3, and that PIAS3 inhibits transcriptional activity of Stat5a/b in breast cancer cells but not in prostate cancer cells. Thus, the proteolytic cleavage of the N-terminus of Stat5a/b may be a mechanism by which Stat5 evades the transcriptional repression by PIAS3 in prostate cancer cells, and results in increased Stat5-driven gene expression and prostate cancer progression.

Matrix metalloproteinase 9 is associated with Gleason score in prostate cancer but not with prognosis

Prostate cancer is the most common cancer in North American men. Among men diagnosed with prostate cancer in more than three cores or with high grade prostate cancer, many experience long disease-free survival. However, these patients still undergo radical treatment while they could benefit from active surveillance with complementary therapy. Matrix metalloproteinase 9 degrades type IV collagen and activates tumorigenic factors and is thus a potential prognostic factor and therapeutic target. This study was thus aimed at investigating the role of matrix metalloproteinase 9 on prostate cancer progression. We correlated matrix metalloproteinase 9 immunohistochemical expression by cancer, stromal and benign epithelial cells with prostate cancer disease-free survival among a cohort composed of 187 pT3NxM0 prostate cancer patients. Median follow-up was 4.63 years and a recurrence occurred in 67 men (35.3%). Matrix metalloproteinase 9 immunostaining was cytoplasmic and expressed at different levels in cancer (94.1%), stromal (87.7%) and benign epithelial cells (94.1%). High levels (>50% of cells) of matrix metalloproteinase 9 expression by prostate cancer cells was strongly associated with high Gleason score (P = .0009). In stromal cells and in benign epithelial cells, high matrix metalloproteinase 9 expression levels were respectively associated with low pT3 substage (P = .046) and with low initial serum prostate-specific antigen levels (P = .006). Matrix metalloproteinase 9 expression level by any cell type was not associated with prostate cancer disease-free survival. These results show that matrix metalloproteinase 9 is overexpressed by cancer cells in high grade tumors and by stromal and benign epithelial cells in lower substage tumors.

Redefining hormone resistance in prostate cancer

Prostate cancer relies on signaling through the androgen receptor (AR) for maintenance and progression; and androgen-deprivation therapy remains a cornerstone of treatment for advanced prostate cancer. An effective clinical classification of prostate cancer should account for the extent of the disease as well as the mechanisms that are driving the growth of the tumor. The previous terms hormone-sensitive and hormone-refractory described response to treatment. It has become clear that these terms do not reflect the mechanism of disease relapse; however over the last decade there has been a better understanding of androgen-receptor mediated signaling effects and incomplete suppression of androgens in prostate cancer. The Prostate Cancer Clinical Trials Working Group 2 (PCWG2) now recommends addressing the spectrum of clinical states based on castration status as this ligand-centered terminology can more accurately describe the patients' disease, and ultimately provides a useful framework for patient management and drug development. Optimized use of androgen-deprivation therapy, low molecular weight inhibitors of adrenal androgen biosynthesis, and new AR antagonists are promising new therapeutics that can further define the meaning of castrate state. As hormone resistance is redefined to include patients that are refractory to treatments that ablate adrenal and in situ tumoral androgens, a meaningful new clinical state in patients will be forged. We propose a model for incorporating these patients into the current PCWG2 conceptualization of the disease.

Use of Virtual Patient Populations for Rescuing Discontinued Drug Candidates and for Reducing the Number of Patients in Clinical Trials

The decreasing cost-efficiency of drug development threatens to result in a severe shortage of innovative drugs, which may seriously compromise patient healthcare. This risk underlines the urgency to change the paradigm in clinical research. Here, we examine a novel concept of conducting virtual clinical trials for efficiently screening drug candidates, and for evaluating their prospects of being brought to the market successfully. The virtual clinical trials are carried out by using virtual patients (denoted Optimata Virtual Patients — OVPs). The OVP, a set of mathematical algorithms that describe the main pathological and physiological dynamic processes affected by the administered drug, has been shown to accurately predict docetaxel efficacy and safety in individual breast cancer patients. We report a test case in which virtual clinical trials have been conducted by using OVP populations for rescuing a discontinued oncology compound, ISIS-5132 (ISIS Pharmaceuticals Inc.). Our in silico study suggested that ISIS-5132 may be efficacious in combination with another drug, sunitinib malate (Sutent®, Pfizer Inc.), for the treatment of prostate cancer. The recommended combined treatment is predicted to result in a higher five-year Progression-Free Survival than monotherapy with either drug alone.

Tumor-Associated Antigens and Biomarkers in Cancer and Immune Therapy

Cancer has currently overtaken heart disease as the major cause of mortality in the United States. The Human Genome Project, advances in informatics, miniaturization of sample collection, and increased knowledge of cell signaling pathways has revolutionized the study of disease. Genomics, proteomics, and metabolomics are currently being used to develop molecular signatures for disease diagnosis, prognosis, and therapeutic efficacy. Tumor-associated antigens discovered by these methods are being used to develop passive (humoral) as well as active immunotherapy strategies to stimulate the immune system. Development and validation of biomarkers on a parallel track with therapeutics can speed development times by accurate screening of patient populations and substituting surrogate markers that correlate well with clinical outcomes.

Ductal adenocarcinoma of the prostate: clinical features and implications after local therapy

BACKGROUND

Ductal or endometrioid adenocarcinoma of the prostate may be a subtype of prostate cancer that is amenable to aggressive local therapeutic strategies. The authors of this report investigated the clinical outcome of patients who had prostate ductal adenocarcinoma after primary radical prostatectomy or radiotherapy.

METHODS

The clinical features of 108 patients with locally confined or advanced prostate ductal adenocarcinoma who had undergone primary radical prostatectomy (surgical group, n = 76 men) or no surgery (nonsurgical group, n = 32 men) were evaluated retrospectively. Clinical records were reviewed, and Gleason scores, clinical/pathologic stages, and preoperative prostate-specific antigen levels were examined. The clinical features that were assessed included local recurrence, distant metastasis, and progression-free and overall survival after primary therapy.

RESULTS

In the surgical group, patients who had pure ductal prostate cancer survived longer (median, 13.8 years; 95% confidence interval [CI], from 13.8 years to not attained) than patients who had mixed ductal prostate cancer (median, 8.9 years; 95% CI, from 7.1 years to not attained; P = .05). In addition, the median time to local progression was shorter (2.8 years vs 4.9 years) and the median time to distant metastasis was longer (3.9 years vs 2.0 years) for patients who had pure ductal adenocarcinoma than for patients who had mixed ductal adenocarcinoma of the prostate after surgery, respectively.

CONCLUSIONS

The results of this preliminary study suggested that pure ductal prostate adenocarcinoma tends to pursue an indolent clinical course and poses an increased risk for local recurrence. Local control (particularly prostatectomy) may improve the clinical outcome of patients with pure prostate ductal adenocarcinoma. These results need to be confirmed in prospective studies.

Regulation of mRNAs encoding MMP-9 and MMP-2, and their inhibitors TIMP-1 and TIMP-2 by androgens in the rat ventral prostate

The relative activities of matrix metalloproteinases (MMPs) and their natural inhibitors (tissue inhibitors of matrix metalloproteinases, TIMPs) determine the extent of matrix degradation in any tissue. Their identification and characterization is key towards understanding remodeling of the prostate in the context of both castration induced atrophy and tumor invasion and metastasis. Although the expression of MMPs and TIMPs in prostate tumors has been reported, their regulation by androgens has not been studied. Here, we show that androgen ablation by castration increases the steady state mRNA levels of MMP-9, MMP-2, TIMP-1 and TIMP-2. Blockade of the androgen receptor using flutamide, however, has differential effects on the steady state mRNA expressions of these genes. We also show that both castration and flutamide treatment cause enhanced expression of a high molecular weight gelatinolytic activity in the rat ventral prostate (RVP). Actinomycin D does not affect the increase in steady state mRNA levels of MMP-9 and TIMP-1. Furthermore we show that actinomycin D alone enhances the steady state mRNA and protein levels of these genes. Using RNA gel shift assay with 3'-UTR of TIMP-1, we show that an RNA binding protein is induced following castration. Taken together our data suggest that the induction of MMP-2, MMP-9, TIMP-1 and TIMP-2 mRNAs post-castration could be at least in part due to post-transcriptional stabilization.

Alterations in beta-catenin expression and localization in prostate cancer

BACKGROUND

Wnt signaling is thought to be important in prostate cancer, in part because proteins such as beta-catenin can also affect androgen receptor signaling. beta-Catenin forms a cell adhesion complex with E-cadherin raising the possibility that loss of expression or a change in beta-catenin distribution in the cell could also alter downstream signaling, decreased inter-cellular adhesion and the promotion of metastasis. A number of studies have reported the altered expression and/or localization of beta-catenin as a biomarker in prostate cancer.

METHODS

Tissue microarrays comprised of BPH and low, moderate and high-grade prostate cancer (n=77) were assessed for beta-catenin expression and distribution using immunohistochemistry. Staining was also performed on a tissue microarray containing tissue from patients before and after hormone manipulation. The effects of fixation and different antibodies was assessed on fixed LNCaP cell pellets and small prostate tissue microarrays.

RESULTS

We have observed increased beta-catenin expression in only high Gleason score (>7) prostate cancer. A nuclear re-distribution of beta-catenin has previously been reported. We noted nuclear beta-catenin in benign prostatic hyperplasia and a gradual loss in nuclear distribution with increasing Gleason grade. We found no evidence for an alteration in beta-catenin expression or re-distribution with hormone ablation. Altered fixation, antibodies and antibody concentration did affect the intensity and specificity of staining.

CONCLUSIONS

A loss of nuclear beta-catenin is the most consistent feature in prostate cancer rather than absolute levels of expression. We also suggest that variation in immunohistochemical protocols may explain variations in the reported literature.

Biomarker expression patterns that correlate with high grade features in treatment naive, organ-confined prostate cancer

BACKGROUND

The early detection of prostate cancer has resulted in an increase in the number of patients with localized prostate cancer and has paralleled the reported reduction in prostate cancer mortality. The increased rate of detection of patients with localized prostate cancer may also increase the risk of potentially morbid therapy in a patient with indolent cancer. Defining the biomarker correlates of prostate cancer virulence will facilitate the appropriate application and development of therapy for patients with early disease.

METHODS

A 255 core prostate cancer tissue microarray (TMA) from 47 prostatectomy specimens with organ confined tumor was constructed. Prostate cancer foci of transition and peripheral zone origin were represented on the TMA. Further, replicate cores of the two Gleason grades comprising the Gleason score, representative of Gleason scores 5-9, were arrayed from each prostatectomy specimen. Standard immunohistochemical techniques were used to assess expression of nine, cell death and cell cycle regulatory proteins implicated in the pathogenesis of prostate cancer (bax, bcl-2, bcl-xL, bin1, CD95, mdm2, p21, p53, and NFkappaB).

RESULTS

The Spearman correlation coefficient revealed a strong correlation of bax, bin1, FAS, p65 and p21 expression with Gleason grade. Spearman correlation coefficients showed that expression of, bax and bin1, bax and MDM2, Bax and p21, and bax and p65 NFkappaB was highly associated. Other significant associations were identified between bin1 and p21, bin1 and MDM2, bin1 and p65 NFkappaB and between p21 and p65 NFkappaB. A model for predicting the biological potential of Gleason score 7 prostate cancer using multivariable logistic regression methods was developed. The findings also indicate that the profile of specific markers for Gleason grade 3 prostate cancer correlates with the overall context of the Gleason score.

CONCLUSION

These data support the view that important molecular differences exist among and between the Gleason scores. Furthermore, there is significant molecular heterogeneity among prostatectomy specimens containing Gleason grade 3 cancer. This observation may have broader implications regarding the determination of risk among patients with prostate cancer that is currently considered to be of either good prognosis or unclear prognosis, i.e. Gleason score 7 tumors.

Dicarbonyl/L-xylulose reductase: a potential biomarker identified by laser-capture microdissection-micro serial analysis of gene expression of human prostate adenocarcinoma

To identify genes involved in prostate carcinogenesis, we used laser-capture microdissection-micro serial analysis of gene expression to construct libraries of paired cancer and normal cells from human tissue samples. After computational comparison of the two libraries, we identified dicarbonyl/l-xylulose reductase (DCXR), an enzyme that catalyzes alpha-dicarbonyl and l-xylulose, as being significantly up-regulated in prostate cancer cells. The specificity of DCXR up-regulation for prostate cancer tissues was confirmed by quantitative real-time reverse transcriptase-PCR, virtual Northern blot, and Western blot analyses. Furthermore, DCXR expression at the protein level was assessed using fresh-frozen tissues and a tissue microarray consisting of 46 cases of organ-confined early-stage prostate cancer and 29 cases of chemohormonally treated prostate cancer. In most normal prostate epithelial cells, DCXR was expressed at low levels and was localized predominantly in the cytoplasmic membrane. In contrast, in virtually all grades of early-stage prostate cancer and in all chemohormonally treated cases, DCXR was strikingly overexpressed and was localized predominantly in the cytoplasm and nucleus. In all samples, the stromal cells were completely devoid of DCXR expression. Based on these findings, we suggest that DCXR overexpression has the potential to be an additional useful biomarker for prostate cancer.

The role of tissue microarrays in prostate cancer biomarker discovery

Tissue microarrays (TMAs) offer the potential to rapidly translate genomics and basic science research findings to practical clinical application. This is particularly true in the field of cancer biomarker research, where TMAs can be used for candidate biomarker validation and association with patient clinical, pathologic, and outcomes parameters. In this review, we examine the effect of TMA use on prostate cancer biomarker research, focusing on the types of TMAs that have been used, and the biomarkers that have been examined. The results demonstrate that TMAs have been very effective in screening candidate biomarkers for subsequent, extended evaluation in large patient populations. In addition, the use of TMAs in multiple biomarker series allows for the statistical analysis of sets of biomarkers as diagnostic or prognostic tests. The processes used here can be applied to any tumor type to improve patient diagnosis, prognosis, and treatment response prediction.

Expression of dicarbonyl/L-xylulose reductase (DCXR) in human skin and melanocytic lesions: morphological studies supporting cell adhesion function of DCXR

BACKGROUND

It has been proposed that dicarbonyl/L-xylulose reductase (DCXR) is increased in prostate cancer. Also, when compared with normal skin, a virtual northern blot shows increased expression of DCXR in melanomas.

METHODS

We investigated DCXR expression in a tissue microarray, with 20 benign and 33 malignant melanocytic lesions and possible colocalization of DCXR with cell adhesion molecules using double immunofluorescence/confocal microscopy in normal human skin.

RESULTS

Most nevi expressed DCXR in the cytoplasmic membrane, but some melanomas (20-30%) showed loss of membranous expression with inappropriate cytoplasmic or nuclear expression. Perinuclear Golgi expression was found in primary (14%) and metastatic (32%) melanomas showing dishesive growth pattern. Overall, the intensity of expression was stronger in nevi compared with melanomas (p < 0.005). In normal skin, DCXR was colocalized with E-cadherin and beta-catenin at the intercellular membranes of keratinocytes and with CD31 at the intercellular junctions of endothelial cells. DCXR was localized in the cytoplasmic membrane of normal melanocytes.

CONCLUSIONS

These findings indicate that decreased membranous expression of DCXR with altered subcellular localization appears to be associated with malignant progression of melanocytic lesions. We show for the first time the expression of DCXR in normal keratinocytes, melanocytes and endothelial cells.

Initial modulation of the tumor microenvironment accounts for thalidomide activity in prostate cancer

PURPOSE

Disruption of stromal-epithelial interactions favoring prostate cancer progression may affect the phenotype of the disease. We did a preoperative study to test the hypothesis that thalidomide, an active agent in metastatic disease, is a modulator of the tumor microenvironment.

EXPERIMENTAL DESIGN

Eighteen men with high-risk prostate cancer were given thalidomide at doses escalated to 600 mg for 12 weeks, followed by radical prostatectomy. We constructed tissue microarrays from prostatectomy specimens from 15 treated patients and 15 matched untreated control subjects to assess effects of thalidomide on the tumor microenvironment. We compared the immunohistochemical expression of three groups of markers linked to angiogenesis, stromal-epithelial interactions, or the epithelial compartment. Levels of circulating basic fibroblast growth factor, interleukin-6, tumor necrosis factor-alpha, and vascular endothelial growth factor were also assessed.

RESULTS

Thalidomide was well tolerated and induced a median reduction in prostate-specific antigen of 41% without affecting testosterone. Tissue microarray analyses indicated modulation of vascular marker expression accompanied by a reduction in microvessel density in the treated group. Comparison of broader stromal-epithelial interaction markers between treated and control groups suggested a transition to a less aggressive phenotype as a result of thalidomide treatment. Hedgehog signaling was attenuated and the ratio of matrix metalloproteinases to E-cadherin shifted to favor E-cadherin. No differences were noted in proliferation or apoptosis in the epithelial compartment.

CONCLUSIONS

These findings are the first clinical evidence to support the hypothesis that the reported thalidomide clinical efficacy is attributable to early modulation of the tumor microenvironment and suggest that stromal-targeting therapies will be effective against prostate cancer.

Small-cell neuroendocrine carcinoma as a variant form of prostate cancer recurrence: a case report and short literature review

BACKGROUND

Small-cell neuroendocrine carcinoma has been recognized as a rare histologic variant occurring in only 0.5% to 2% of prostatic primary tumors. However, recent autopsy studies suggest development to this phenotype in up to 10% to 20% of the cases with hormone-refractory disease.

CASE PRESENTATION

A case of conventional adenocarcinoma before androgen-ablation therapy but showing progression to small-cell neuroendocrine carcinoma at the recurrence. The immunohistochemistry of the tumor showed strong positive staining for progastrin-releasing peptide (ProGRP), a carboxy terminal region common to 3 precursors for gastrin-releasing peptide, but almost negative staining for chromogranin-A and prostate-specific antigen. Combination chemotherapy based on cisplatin and etoposide was effective for controlling the tumor progression for 7 months, and the serum ProGRP level correlated well to the clinical course. Neither objective nor subjective responses were observed to somatostatin analogue therapy performed in the late stage of disease.

CONCLUSIONS

The present case reminds the urologist that small-cell neuroendocrine carcinoma may be a variant form of disease recurrence during androgen ablation in advanced prostate cancer. A strategic approach for this phenotype evaluating serum neuroendocrine markers, such as ProGRP, should be taken when serum prostate-specific antigen does not reflect the disease state. This approach would allow one to choose alternative therapies targeting neuroendocrine cells other than androgen ablation.

Molecular markers of prostate cancer

Although prostate-specific antigen (PSA) has evolved as a very useful tool for detection of prostate cancer, there remains an urgent need for more accurate biomarkers to diagnose prostate cancer and predict cancer-related outcomes. Recent advances in the study of proteomics and high throughput techniques have led to the discovery of many potential biomarkers for prostate cancer. This article briefly reviews the current status of PSA testing and discusses several candidate protein biomarkers for prostate cancer, as well as highlighting some recent proteomic discoveries with the potential to supplement or even replace PSA for the diagnosis and prognosis of prostate cancer.

Molecular markers in the diagnosis of prostate cancer

The genetic alterations leading to prostate cancer are gradually being discovered. A wide variety of genes have been associated with prostate cancer development as well as tumor progression. Knowledge of gene polymorphisms associated with disease aid in the understanding of important pathways involved in this process and may result in the near future in clinical applications. Urinary molecular markers will soon be available to aid in the decision of repeat prostate biopsies. Recent findings suggest the importance of androgen signaling in disease development and progression. The further understanding of interaction of inflammation, diet, and genetic predisposition will improve risk stratification in the near future.

Novel role of Stat1 in the development of docetaxel resistance in prostate tumor cells

A major obstacle for clinicians in the treatment of advanced prostate cancer is the inevitable progression to chemoresistance, especially to docetaxel. It is essential to understand the molecular events that lead to docetaxel resistance in order to identify means to prevent or interfere with chemoresistance. In initial attempts to detect these events, we analysed genomic differences between non-resistant and docetaxel-resistant prostate tumor cells and, of the genes modulated by docetaxel treatment, we observed Stat1 and clusterin gene expression heightened in the resistant phenotype. In this study, we provide biochemical and biological evidence that these two gene products are related. Stat1 and clusterin protein expression was induced upon docetaxel treatment of DU145 cells and highly overexpressed in the docetaxel-resistant DU145 cells (DU145-DR). The increase in total Stat1 corresponded to an increase in phosphorylated Stat1. Interestingly, there was no detectable difference between DU145 and DU145-DR cells expression of total Stat3 and phosphorylated Stat3. Treatment of DU145-DR cells with small interfering RNA targeted for Stat1 not only resulted in the knockdown of Stat1 expression, but it also caused the inhibition of clusterin expression. Thus, Stat1 appears to play a key role in the regulation of clusterin. Remarkably, inhibition of Stat1 or clusterin expression resulted in the re-sensitization of DU145-DR cells to docetaxel. These results offer the first evidence that Stat1, and its subsequent regulation of clusterin, are essential for docetaxel resistance in prostate cancer. Targeting this pathway could be a potential therapeutic means for intervention of docetaxel resistance.

Safety and Tolerability of PCK3145, a Synthetic Peptide Derived from Prostate Secretory Protein 94 (PSP94) in Metastatic Hormone-Refractory Prostate Cancer

BACKGROUND

The safety, tolerability, and pharmacokinetic and preliminary efficacy of PCK3145 were determined in patients with metastatic hormone-refractory prostate cancer.

PATIENTS AND METHODS

PCK3145 was administered in ascending doses of 5, 20, 40, and 80 mg/m2 3 times per week for 4 weeks to cohorts of 4 patients. Dose escalation was based on dose-limiting toxicity (DLT). Pharmacokinetic profiles, tumor burden, and tumor markers (including prostate-specific antigen [PSA] and matrix metalloproteinase-9 [MMP-9] levels) were assessed. Sixteen patients received PCK3145. The median age was 66 years, and the median PSA level was 232.5 microg/L. A total of 32 cycles of therapy were administered.

RESULTS

The most common adverse events reported were pain and nausea. The only DLT was a grade 4 cardiac arrhythmia in a patient treated at the 80-mg/m2 dose level. Pharmacokinetic analysis using a 2-compartment model indicated that the mean area under the curve values increased as the dose range increased, and the mean elimination half-life ranged from 0.35 hours to 1.45 hours. The best tumor response was stable disease in 10 patients and progressive disease in 5 patients. No PSA responses were observed, but 1 patient showed a marked reduction in PSA of 41% at cycle 2. A substantial reduction in MMP-9 levels was observed in patients with baseline levels of MMP-9 > 100 microg/L.

CONCLUSION

PCK3145 was safe and well tolerated at all doses. Efficacy observations were encouraging, and the biologic activity of PCK3145 in reducing MMP-9 level may suggest a potential role of this peptide in the regulation of metastatic tumor growth.