Pathological and molecular aspects of prostate cancer

Switch to full-length of XAF1 mRNA expression in prostate cancer cells by the DNA methylation inhibitor

X-linked inhibitor of apoptosis protein (XIAP) suppresses apoptotic cell death by binding to caspases and inhibiting their functions, while the XIAP-associated factor1 (XAF1), a zinc finger protein, antagonizes XIAP activities, thereby promoting apoptosis. The aberrant silence of the XAF1 gene has recently been found in various types of cancer cells, which is suggested to be one of the potential mechanisms underlying survival advantages of malignant cells. In the present study, we investigated the XAF1 expression in prostate cancer cells. Compared with normal tissues where a full-length of XAF1 mRNA is predominant, LNCaP and DU145 prostate cancer cell lines only expressed a short form of XAF1 transcripts, whereas PC3 cells exhibited a complete silence of the XAF1 gene. Inhibition of DNA methylation led to a switch to the full length of XAF1 mRNA expression in LNCaP and DU145 cells. The down-regulation of XAF1 expression was also observed in 6/8 tumor samples derived from patients with prostate cancer. Our findings suggest that splicing alterations or downregulation of the XAF1 transcript may occur during the development of prostate cancers due to the aberrant DNA methylation. The alternative splicing of XAF1 mRNA leads to formation of a truncated XAF1 protein with 19 amino acid deletion in its zinc finger domain, which likely affects its functional interaction with XIAP, and consequently, contributes to the pathogenesis of prostate cancers by disrupting balance of the apoptosis machinery.

Myofibroblastic stromal reaction and expression of tenascin-C and laminin in prostate adenocarcinoma

The aim of this study was to analyse relationship between changes of the stroma and expression of tenascin-C (TN-C) and laminin in prostate carcinoma. Tenascin-C immunostaining was increased, and laminin decreased in carcinomas compared with peritumoral tissue and benign prostate hyperplasia (P<0.05). Statistical analysis confirmed connection between stromal changes and TN-C expression in prostate carcinoma (P<0.05). Gleason pattern 3 carcinomas showed more pronounced stromal reaction and TN-C expression compared with Gleason pattern 4 carcinomas (P<0.05). The main cells in prostate cancer stroma are myofibroblasts that are also responsible for tenascin production. Degradation of laminin was not connected with myofibroblastic stromal changes.

NKX3.1 stabilizes p53, inhibits AKT activation, and blocks prostate cancer initiation caused by PTEN loss

We demonstrate that PTEN loss causes reduced NKX3.1 expression in both murine and human prostate cancers. Restoration of Nkx3.1 expression in vivo in Pten null epithelium leads to decreased cell proliferation, increased cell death, and prevention of tumor initiation. Whereas androgen receptor (AR) positively regulates NKX3.1 expression, NKX3.1 negatively modulates AR transcription and consequently the AR-associated signaling events. Consistent with its tumor suppressor functions, NKX3.1 engages cell cycle and cell death machinery via association with HDAC1, leading to increased p53 acetylation and half-life through MDM2-dependent mechanisms. Importantly, overexpression of Nkx3.1 has little effect on Pten wild-type epithelium, suggesting that PTEN plays a predominant role in PTEN-NKX3.1 interplay. Manipulating NKX3.1 expression may serve as a therapeutic strategy for treating PTEN-deficient prostate cancers.

Toremifene--a promising therapy for the prevention of prostate cancer and complications of androgen deprivation therapy

Deregulation of the estrogen axis in humans prompts a series of tissue-specific events. In the breast and prostate, alterations in estrogen signalling lead to genotypic and phenotypic molecular alterations that result in dysplastic cellular appearance, deregulated cell growth and carcinoma. In bone, decreased estrogen leads to increased osteoclastogenesis and bone resorption, decreased bone mineral density and a significant fracture risk. Toremifene is a selective estrogen receptor modulator that exerts pharmacological activity in the breast, bone and prostate. An intense interest in developing this agent for prostate cancer chemoprevention is based on the reduction of premalignant and malignant prostate lesions in a transgenic model of prostate cancer. Biological and clinical activity was demonstrated in Phase II trials by the prevention of progression to prostate cancer in men with high-grade prostate intraepithelial neoplasia and through suppression of bone turnover biomarkers and increased bone mineral density in men on androgen deprivation therapy for prostate cancer.

Synthetic dimer of indole-3-carbinol: second generation diet derived anti-cancer agent in hormone sensitive prostate cancer

BACKGROUND

Cruciferous vegetables have been found to have anti-prostate cancer effects. The active compounds mediating these effects include indoles such as indole-3-carbinol (I3C) and isothiocyanates. I3C is unstable having tissue tropic effects and clinical utility has been partly addressed by the synthesis of a more stable dimer diindolylmethane (DIM).

METHODS

Anti-proliferative activity was measured by XTT assay and cytosolic proteins quantitated by Western blot analysis.

RESULTS

DIM (IC(50) 50 microM) is a better anti-proliferative agent than I3C (IC(50) 150 microM) in androgen dependent LNCaP cells, inhibits DNA synthesis, and growth of R1881 stimulated LNCaP cells. Androgen receptor (AR), cyclin D1, and cdk4, induced by R1881, are downregulated by DIM. DIM downregulates phosphorylated Akt and phosphatidyl inositol 3-kinase and downstream inhibition of cyclin D1 and cdk4.

CONCLUSION

These studies provide evidence that DIM is a second-generation chemopreventive agent with a viable cellular target and has clinical potential as an anti-prostate cancer chemopreventive.

Quantitative PSA mRNA determination in blood: a biochemical tool for scoring localized prostate cancer

OBJECTIVES

Our aim was to verify whether the quantitative determination of PSA mRNA in circulating cells is helpful in diagnosing and scoring localized prostate cancer (PC).

DESIGN AND METHODS

The study included 145 patients with benign prostatic hyperplasia (BPH), 138 with localized PC and 28 healthy controls (CS). PSA cDNA was amplified by real-time PCR from circulating mononuclear cells. Serum total and free PSA were determined. Prostate cancers were histologically scored according to the Gleason criteria.

RESULTS

The most sensitive index of PC was tPSA (70%), and the most specific was f/t PSA (80%). High PSA mRNA was found more frequently in PC patients with poorly differentiated (23.1%) than in those with well (4.5%) or moderately (4.3%) differentiated tumors.

CONCLUSIONS

tPSA and f/t PSA are the best available tools for discriminating between localized PC and BPH. The quantitative assessment of PSA mRNA in blood might be helpful in the biochemical grading of prostate cancer.

Methylation of apoptosis related genes in the pathogenesis and prognosis of prostate cancer

We investigated aberrant methylation in 101 prostate cancers(PCa) and 32 histologically normal prostate tissues. We focused on genes largely in the apoptotic pathway. Methylation frequencies of the genes were Reprimo, 54%; TMS1, 47%; DcR1, 45%; RRAD, 37%; DcR2, 37%; CRBP1, 34%; HPP1, 32%; RIZ1, 31%; DRM/Gremlin, 21%; SOCS1, 20%; DR4, 5%; DR5, 1%. Methylation of Reprimo and TMS1 correlate with preoperative serum prostate-specific antigen. Methylation of TMS1, DcR1, DcR2, and CRBP1 correlate with Gleason score. Methylation of TMS1 and unmethylation of both DcR1 and DcR2 correlate with poorer disease free survival by univariate and multivariate analyses. Our data suggest that methylation of multiple genes may be involved in pathogenesis and correlate with prognosis of PCa.

Prostatic intraepithelial neoplasia and adenocarcinoma in mice expressing a probasin-Neu oncogenic transgene

NEU (ERBB2) and other members of the epidermal growth factor receptor (EGFR) family have been implicated in human prostate cancer (CAP) development and progression to an androgen-independent state, but the extent of involvement and precise role of this signaling pathway remain unclear. To begin addressing such open questions in an animal model, we have developed a transgenic line in which an oncogenic Neu cDNA (Neu*) driven by the probasin gene promoter is overexpressed in the mouse prostate and causes development of prostatic intraepithelial neoplasia (PIN) that progresses to invasive carcinoma. Expression profiling using microarrays, which was selectively validated and extended by immunophenotyping of Neu*-induced PIN and CAP, led to the identification of some novel biomarkers and also revealed increased expression of Egfr, Erbb3 and phosphorylated androgen receptor. In view of this information from our mouse model, which can be used to analyze further the role of Erbb signaling in prostatic tumorigenesis, we examined human prostate cancer tissue arrays by immunohistochemistry. Based on statistical analyses of the results, we propose the testable hypothesis that ERBB3, shown to be expressed in 86% of the human CAP cases that we examined, is the pivotal element of the Erbb pathway promoting tumorigenesis by heterodimerization with NEU or EGFR, while a NEU/EGFR dimer does not appear to play a significant role in CAP.

Overexpression of metastatic tumor antigen in osteosarcoma: comparison between conventional high-grade and central low-grade osteosarcoma

PURPOSE

The metastatic tumor antigen (MTA) gene is a recently identified metastasis-associated gene which has implications in the signal transduction or regulation of gene expression. However, the expression of MTA in osteosarcoma and its potential relationship with metastasis have not been examined, forming the basis of this study.

MATERIALS AND METHODS

We compared the expression levels of the MTA1 protein between 32 cases of high-grade osteosarcomas and 21 cases of low-grade osteosarcomas by immunohistochemistry. In addition, the mRNA expression levels of MTA1, 2, 3 in these osteosarcoma cell lines and control fibroblasts were evaluated by real-time quantitative PCR.

RESULTS

MTA1 immunoreactivity was present in 81.25% of high-grade osteosarcoma specimens. Its expression was predominantly localized to the nucleus or cytoplasm of osteosarcoma cells. Thirteen (86.6%) of 15 patients who died of osteosarcomas displayed strong MTA1 expression. Both primary bone and pulmonary metastatic lesions exhibited MTA1 expression. All low-grade osteosarcomas were negative for MTA1 except for focal weak reactivity in two cases. The tested high-grade osteosarcoma cell lines showed marked amplification of MTA1 and MTA2 mRNA compared to control cells.

CONCLUSION

These results suggest that MTA might be involved in the progression of high-grade osteosarcoma, particularly in hematogenous metastasis of osteosarcoma.

Atrophy in prostate needle biopsy cores and its relationship to prostate cancer incidence in screened men

OBJECTIVES

To evaluate whether the incidence of atrophy reported on sextant biopsies is associated with subsequent prostate cancer detection and to obtain a more thorough analysis of the different categories and extent of atrophy, we performed a review of benign biopsy cores.

METHODS

In the Rotterdam section of the European Randomized Study of Screening for Prostate Cancer, 4117 and 1840 men underwent sextant biopsy in the first and second screening round (4-year interval), respectively. Sextant biopsy was prompted by elevated prostate-specific antigen levels. For review, randomly taken benign sextant biopsies (n = 202) with a follow-up of at least 8 years were chosen.

RESULTS

Before review, atrophy was reported in the biopsies of 11.4% and 8.7% of the first and second round, respectively. The prostate cancer incidence during 8 years of follow-up after an initial diagnosis of atrophy was 10.4%, which was not significantly different than the 12.3% of cancers detected after a benign diagnosis without reference to atrophy. After review, the incidence of simple atrophy, post-atrophic hyperplasia, and sclerotic atrophy in sextant biopsies was 91%, 47%, and 9%, respectively. Extensive atrophy was observed in 5% of biopsies. Only 2 men (4.7%) in the reviewed group had a subsequent diagnosis of prostate cancer in the 8 years of follow-up. Additionally, prostatic intraepithelial neoplasia was diagnosed in 3 men (7.0%) in the second screening round.

CONCLUSIONS

Atrophy, especially its simple form, is a very common lesion in prostate biopsy cores (94%). Atrophy in an asymptomatic population undergoing screening was not associated with a greater prostate cancer or prostatic intraepithelial neoplasia incidence during subsequent screening rounds.

Prognostic and predictive factors and reporting of prostate carcinoma in prostate needle biopsy specimens

The information provided in the surgical pathology report of a prostate needle biopsy of carcinoma has become critical in the subsequent management and prognostication of the cancer. The surgical pathology report should thus be comprehensive and yet succinct in providing relevant information consistently to urologists, radiation oncologists and oncologists and, thereby, to the patient. This paper reflects the current recommendations of the 2004 World Health Organization-sponsored International Consultation, which was co-sponsored by the College of American Pathologists. It builds on the existing work of several organizations, including the College of American Pathologists, the Association of Directors of Anatomic and Surgical Pathologists, the Royal Society of Pathologists, the European Society of Urologic Pathology and the European Randomized Study of Screening for Prostate Cancer.

Genomics of prostate cancer: Is there anything to „translate”?

This review provides an up-dated collection of data concerning the genetic and epigenetic changes during development, growth and progression of prostate cancer. Hereditary and susceptibility factors have a long list, similarly to the expression of single genes connected to various cell functions. It was a hope that covering a large set of genes, array technologies would clarify very rapidly the role of genetics in malignant diseases, offering targets for molecular diagnostics and therapy. The power of high-throughput techniques for the detection and global analysis of gene expression is unquestionable, interesting, astonishing as well as puzzling data have already been obtained. However, the standardization of the procedures is still missing and the reproducibility is rather low in many instances. Moreover, the different array methods can select different gene expression profiles, which makes the decision rather difficult. Another important question is, coming again from the array technologies, how far the genotype (the gene profiles or fingerprints) can reflect the actual phenotype in a highly complex and readily changing disease as cancer. Proteomics will provide a closer look to this seemingly unanswerable problem. We are at the beginning of the exploration of the behavior of cancer cells in order to apply a more effective therapy based on a more reliable set of diagnostic and prognostic informations.

Gleason-Grading

Prostate cancer offers a wide spectrum ranging from clinically insignificant to aggressive and fatal disease. The Gleason grade is a powerful prognostic indicator and does influence treatment decision. Educational programs and websites are currently available to improve reproducibility and reliability of Gleason grading. A major problem in reporting of Gleason grading in needle biopsy is undergrading. The Gleason grade 3 is the lowest grade which can be assigned reliably in needle biopsies. The major prognostic shift is between Gleason grades 3 und 4 which is characterized by fusion of the glandular formations. Reporting the proportion of Gleason grades 4 and 5 in needle biopsies may be critical in terms of treatment decisions. The present review deals with diagnostic criteria of the Gleason grades and its clinical implications.

[Ophthalmoplegia in a patient with prostate cancer and bone metastases]

Prognosis in prostate cancer is determined, in greater part, by the presence of metastases. Bone metastases can occur in any part of the skeleton even, for example, at the base of the skull. We present a case of a 78 year old male who, in December 2001, presented with paralysis of the third cranial nerve. The NMR and CAT scans were normal and circulating levels of PSA were elevated. He was referred to the Urology Service where the treatment guidelines included complete androgen block. Subsequently, he developed retro-orbital pain, divergent strabismus and palpebral ptosis. CAT and NMR indicated a soft tissue mass at the sphenoid level. Treatment was Gamma Knife Radio-surgery. Since August 2004, in conjunction with the latest rise in PSA, the patients general status deteriorated considerably and he was referred to the Oncology Service. There was an increase in the paralysis of the third, fourth and sixth cranial nerve (complete left ophthalmoplegia) and left-central facial paralysis. Metastases from prostate cancer can be disseminated via the lymphatic or the blood system. Currently, there are more metastases from large-size tumours. Metastases are critical in prostate cancer because of their adverse effect on the patients survival. Measurements of circulating levels of prostate specific antigen and prostate acid phosphatase are very useful in the clinical diagnosis of the primary tumour, or its metastases.

[Prognostic factors in prostate cancer]

Since several therapeutic options are currently available for clinically organ-confined prostate cancer, morphological parameters have rapidly emerged as prognostic factors to stratify patients into different therapeutic modalities. In addition to the PSA value, pathologic stage, as defined by the TNM system, Gleason grade and the surgical margin status, other markers have prognostic implications. This includes the percent pattern 4/5 cancer, tumor volume, intraductal spread, large volume perineural invasion and molecular markers. This review discusses the methods of sampling and reporting in prostate pathology with an emphasis on well established and new prognostic factors.

p16 Is upregulated in proliferative inflammatory atrophy of the prostate

BACKGROUND

Proliferative inflammatory atrophy (PIA) of the prostate is a common histological finding that has been postulated to be associated with prostate cancer. We examine PIA lesions for the expression of p16/CDKN2, a cyclin-dependent kinase inhibitor frequently altered in prostate cancer.

METHODS

Within tissues from two independent patient populations ("Test Set" and "Validation Set") undergoing radical prostatectomy, PIA lesions were identified and subjected to immunohistochemical staining for p16. Atrophic epithelial cells and regional normal epithelium were scored for the extent of p16 staining. In the Test Set, staining was also performed for the proliferation marker Ki-67. Double label immunofluorescence was employed to co-localize staining for p16 and Ki-67.

RESULTS

p16 expression was elevated in PIA in both data sets compared to normal epithelium (mean percent of cells staining positive in PIA = 11.1%-16.2%; mean percent of cells staining positive in normal = 0.6%-1.3%) (P = 0.0001). As expected from prior studies, the mean Ki-67 index was higher in PIA lesions (mean 8.2% staining positive) versus normal epithelium (mean 1.9% staining positive) (P = 0.0001), and the extent of staining for p16 correlated with Ki-67 (r = 0.7, P < 0.0001). However, co-localization immunofluorescent studies did not demonstrate staining for nuclear p16 and Ki-67 in the same cells.

CONCLUSIONS

Increased p16 expression accompanies increased cell proliferation in PIA lesions of the prostate. Yet, on the individual cell level, the upregulation of p16 in PIA lesions appears to represent a non-proliferative stress response, possibly to oxidative damage.

Prostate cancer and the genomic revolution: Advances using microarray analyses

The emerging technology of microarray analysis allows the establishment of molecular portraits of prostate cancer and the discovery of novel genes involved in the carcinogenesis process. Many novel genes have already been identified using this technique, and functional analyses of these genes are currently being tested. The combination of microarray analysis with other recently developed high-throughput techniques, such as proteomics, tissue arrays, and gene promoter-methylation, especially using tissue microdissection methods, will provide us with more comprehensive insights into how prostate cancer develops and responds to gene-targeted therapies. Animal models of prostate cancer are being characterized by high throughput techniques to better define the similarities and differences between those models and the human disease, and to determine whether particular models may be useful for specific targeted therapies in pre-clinical studies. Although profiling of mRNA expression provides important information of gene expression, the development of proteomic technologies will allow for an even more precise global insight into cellular signaling and structural alterations during prostate carcinogenesis. Not only will the "omic" revolution change basic science, but it will lead to a new era of molecular medicine.

Molecular pathology of prostate cancer

The molecular pathology of prostate cancer is complex; not only are multiple genes involved in its pathogenesis, but additional environmental factors such as diet and inflammation are also involved. The exhaustive research into prostate cancer to date has demonstrated a complex interaction of multiple genes and environmental factors, some of which may be more important in individual prostate cancer cases. This is an exciting era, with the emergence of new investigative tools such as DNA microarray technology and the application of the field of proteomics to the study of human cancers. Knowledge of genetic changes underlying the initiation, development, and progression of prostate cancer is accumulating rapidly. With increasing knowledge, it may be possible to distinguish indolent from aggressive prostate tumours by molecular fingerprinting. This review discusses the most consistently reported molecular pathological findings in hereditary and sporadic prostate cancer, together with new concepts and technologies.

Molecular pathology of prostate cancer

The incidence of prostate cancer has increased in Japan recently and is developing into a life-threatening disease for many Japanese men. This is a result of several convergent factors including the adoption of a Western lifestyle, the widespread use of prostate-specific antigen (PSA) testing, and an increased population of advanced years in Japanese men. Although there is much information to date relating to molecular events underlying the etiology of prostate cancer, it is still unclear as to how and when these genetic alterations occur in each step of tumorigenesis. One fruitful area of investigation has been in the analysis of chromosomal abnormalities commonly observed in prostate cancer. However, no single candidate gene has been definitely identified in cancer initiation and/or progression; in addition, less research has been devoted to understanding the molecular events that underlie tumor histogenesis in terms of likely precursor lesions, such as prostatic intraepithelial neoplasia (PIN). This article reviews the current knowledge of the molecular pathology of prostate cancer, including its histogenesis, genetic and epigenetic alterations, and hereditary factors.

Expression of dentin sialophosphoprotein in human prostate cancer and its correlation with tumor aggressiveness

Recent studies have demonstrated that two SIBLING family members, bone sialoprotein (BSP) and osteopontin (OPN), are overexpressed in human prostate cancer. The expression of these proteins is associated with the acquisition of a metastatic phenotype by cancer cells and a poor prognosis for the patient. Dentin sialophosphoprotein (DSPP) shares several structural and genetic features with OPN and BSP. The presence of DSPP has been recently established in salivary glands, indicating that its expression is not restricted to mineralized tissues. However, its potential expression in human tumors has not been addressed yet. In this study, we sought to evaluate the expression of DSPP in human prostate cancer. Immunohistochemistry was performed on 69 prostate cancer specimens using LFMb-21 anti-DSPP monoclonal antibody. All of the prostate cancer lesions examined expressed detectable levels of DSPP, as compared with no or low level of expression in adjacent normal glands (p < 0.0001). High grade prostatic intraepithelial neoplasia (HGPIN) glands generally displayed DSPP expression levels that were similar to those found in neighboring cancer glands. DSPP expression was significantly associated with the pathological stage (p = 0.0087) and the Gleason score (p = 0.0176) of the tumors. Western Blot was performed on 5 representative prostate tumor extracts and 3 prostatic tumor cell lines (PC3, LNCaP and DU145). All tumor extracts and cell lines analyzed have been found to express DSPP. In addition, in situ hybridization was used to assess the presence of DSPP mRNA. DSPP was detected at the RNA level in both HGPIN and tumoral glands. This study shows for the first time that DSPP is ectopically expressed in human prostate cancer. The expression of this SIBLING protein strongly correlates with conventional histopathological prognostic indicators of prostate cancer progression.

Gleason grading and volume estimation in prostate needle biopsy specimens: evolving issues

The Gleason grading system for prostate cancer is a powerful tool that can help choose therapy and predict outcome for patients. The clinical use and problem areas of the Gleason grading system are reviewed. The issues discussed include grade discrepancies between prostate biopsy and resection specimens, grading small foci of tumor, diagnosing and grading cribriform lesions, reporting the grade when 3 grades of cancer are present in a specimen, and assignment of grade when multiple cores of differing grades are present. Finally, differing ways of communicating tumor volume and the percentage of high-grade carcinoma in prostate biopsy cores are considered.

Constitutive activation of P I3 K-Akt and NF-kappaB during prostate cancer progression in autochthonous transgenic mouse model

BACKGROUND

Cancer progression is usually facilitated by independent growth signals that may lead to increased cell survival and evasion of apoptosis. Phosphatidylinositol 3'-OH kinase (P I3 K)-Akt and transcription factor NF-kappaB are important signaling molecules and key survival factors involved in the control of cell proliferation, apoptosis, and oncogenesis. Although P I3 K-Akt and NF-kappaB have been implicated in the development and progression of prostate cancer, expression of these molecules during progression of autochthonous disease has not been elucidated.

METHODS

Prostate cancer growth and progression in autochthonous transgenic adenocarcinoma of the mouse prostate (TRAMP) mice and male non-transgenic littermates were observed by magnetic resonance imaging (MRI). Expression patterns of P I3 K-Akt, NF-kappaB, I kappaB, and associated signaling molecules during different stages of cancer progression in these mice were examined by Western blot analysis, electrophoretic mobility shift assay (EMSA), enzyme-linked immunoabsorbent assay (ELISA), kinase assay, and immunohistochemistry.

RESULTS

Sequential MRI and gross analysis of prostate gland exhibited increasing prostate volume associated with the development and progression of prostatic adenocarcinoma in TRAMP mice, compared to male non-transgenic littermates. Differential protein expression of P I3 K, phosphorylated-Akt (Ser 473), I kappa Balpha and its phosphorylation, IKK kinase activity, NF-kappaB/p65, p50, DNA binding, and transcriptional-regulated genes, viz., Bc l2, cyclin D1, MMP-9, and VEGF were observed during prostate cancer progression in TRAMP mice, compared to male non-transgenic littermates. Expressions of these molecules were significantly increased during cancer progression observed at 24 and 32 weeks of age.

CONCLUSIONS

Differential expression pattern of P I3 K-Akt, NF-kappaB and I kappaB during prostate cancer progression in TRAMP mice suggest that these molecules represent potential molecular targets for prevention and/or therapeutic intervention.

Divergent biological effects of estradiol and diethylstilbestrol in the prostate cancer cell line MOP

The involvement of mutated androgen receptors (mut-AR) in the actions of estrogens in prostate cancer cells is controversial. This work was designed to determine the role of such receptors in the growth inhibition by estradiol (E2) and androgens of the MOP cell line, a derivative of the LNCaP cell line. Diethylstilbestrol (DES) was used as a "tool". E2 like DHT and R1881 inhibits MOP cell proliferation while DES does not. E2 and R1881 down regulate mut-AR mRNA, DES does not. E2 enhances mut-AR transcriptional activity less efficiently than R1881 while DES does not. E2 and R1881 up regulate PSA secretion in a dose-dependent manner, DES does it marginally at 10(-6)M. MOP cells express low amounts of ERalpha and ERbeta mRNA but neither DES nor E2 and R1881 do enhance ER transcriptional activity. DES and E2 bind to mut-AR with relative binding affinities which are respectively 1/175 and 1/10 that of DHT. The E2 and androgen-repressed proliferation is prevented by DES and by the anti-androgen bicalutamide. In LNCaP cells, DES prevents the androgen-enhanced proliferation. These results strongly suggest that: (a) the putative endogenous ERs are biologically inactive in MOP cells, (b) the E2-repressed proliferation results from hormone binding to mut-AR and, (c) DES is an anti-androgen in mut-AR expressing cell line.

Unopposed c-MYC expression in benign prostatic epithelium causes a cancer phenotype

BACKGROUND

We have sought to develop a new in vivo model of prostate carcinogenesis using human prostatic epithelial cell cultures. Human prostate cancers frequently display DNA amplification in the 8q24 amplicon, which leads to an increase in the copy number of the c-MYC gene, a finding that suggests a role for c-MYC in human prostate carcinogenesis. In addition overexpression of c-MYC in transgenic mouse models results in prostatic carcinogenesis.

METHODS

We took advantage of the ability of retroviruses to integrate foreign DNA into human prostatic epithelium (huPrE) to generate cell lines that overexpress the c-MYC protooncogene. These cells were recombined with inductive rat urogenital sinus mesenchyme and grafted beneath the renal capsule of immunocompromised rodent hosts.

RESULTS

The resultant tissue displayed a phenotype consistent with a poorly differentiated human prostatic adenocarcinoma. The tumors were rapidly growing with a high proliferative index. The neoplastic cells in the tumor expressed both androgen receptors (AR) and prostate-specific antigen (PSA), both characteristic markers of human prostate cancers. Microarray analysis of human prostatic epithelial cells overexpression c-MYC identified a large number of differentially expressed genes some of which have been suggested to characterize a subset of human cancers that have myc overexpression. Specific examples were confirmed by Western blot analysis and include upregulation of c-Myb and decreased expression of PTEN. Control grafts using either uninfected huPrE or using huPrE cells infected using an empty vector expressing a green fluorescent protein tag gave rise to well differentiated benign prostatic glandular ducts.

CONCLUSIONS

By using a retroviral infection strategy followed by tissue recombination we have created a model of human prostate cancer that demonstrates that the c-MYC gene is sufficient to induce carcinogenesis.

Diagnostic and Prognostic Information in Prostate Cancer with the Help of a Small Set of Hypermethylated Gene Loci

PURPOSE

Our study was designed to evaluate promoter CpG island hypermethylation in the diagnosis and prognosis of prostate cancer.

EXPERIMENTAL DESIGN

Primary prostate cancers from 53 patients, pelvic lymph nodes, noncancerous prostate tissues, and prostate cell lines were analyzed. Real-time methylation-specific PCR was used to identify CpG island hypermethylation at five promising gene loci (i.e., GSTP1, APC, PTGS2, MDR1, and RASSF1a).

RESULTS

At three gene loci (GSTP1, APC, and PTGS1) and CpG island, hypermethylation was highly prevalent in prostate cancers (71-91%), and analysis of receiver operator curves showed that hypermethylation at these three gene loci can distinguish between prostate cancer and noncancerous prostatic tissue (i.e., benign hyperplasia) with a sensitivity of 71.1% to 96.2% and a specificity of 92.9% to 100%. Using sensitive SYBR green methylation-specific PCR technology, we observed a respective 28% and 71% hypermethylation rate at the RASSF1a and MDR1 loci in benign prostate hyperplasia, which may represent early nonaggressive carcinogenesis. Methylation characteristics in prostate cancer metastases (i.e., pelvic lymph nodes) were comparable to the respective primary cancer. Statistical analysis showed no correlation between the methylation status of a single gene locus and clinicopathologic variables (e.g., preoperative prostate specific antigen levels, Gleason score, capsular penetration, involvement of seminal vesicle, and age). In contrast, the methylation of two (GSTP1/APC; GSTP1/PTGS2) or three (GSTP1/APC/PTGS2) gene loci correlated with prognostic indicators (i.e., pathologic stage, extraprostatic extension, and Gleason score, but not with prostate specific antigen levels).

CONCLUSIONS

Our data suggest that the evaluation of DNA hypermethylation at three gene loci (i.e., GSTP1, APC, and PTGS2) is of diagnostic and prognostic value in prostate cancer.

Androgen receptor mutants detected in recurrent prostate cancer exhibit diverse functional characteristics

BACKGROUND

Alterations in the function of androgen receptor (AR) and its signaling pathway may be responsible for the progression of prostate cancer. The goal of the present study was to investigate the potential roles of AR structural and functional alterations in the progression of prostate cancer, and the relationship between the structure and function of the AR.

METHODS

AR gene in 58 prostate cancer samples was examined for mutations using PCR-single strand conformation polymorphism (SSCP) analysis and DNA sequencing. Effects of mutations on the structure and function of AR were investigated by androgen-binding assays and transactivation assays, respectively.

RESULTS

Four novel somatic mutations (G142V, D221H, E872Q, and M886I) were identified from recurrent prostate cancer samples. None of the AR mutants differed from wild-type AR (wtAR) in their abilities to bind the synthetic androgen methyltrienolone. However, these mutated AR exhibited diverse functional characteristics as compared with wtAR. G142V and D221H showed increased responses to DHT. E872Q could be abnormally activated by 17beta-estradiol, progesterone, and cyproterone acetate (CPA). Furthermore, E872Q and M886I presented increased responses to DHT in the presence of coactivators TIF-2 and CBP, but not p300. On the other hand, although overexpression of corepressors N-CoR and SMRT could result in evident inhibition on DHT- or CPA-induced transactivity of wtAR and the AR mutants, N-CoR displayed stronger inhibitory effects on DHT-induced transactivity of the AR mutants (especially for E872Q and M886I) than that of wtAR. To our knowledge, this is the first characterization of enhanced inhibitory effects of corepressors on the transactivity of the AR mutants found in prostate cancer.

CONCLUSIONS

The data presented here demonstrate that AR mutants found in prostate cancer had different functional alterations, which might play an important role in the progression of prostate cancer.

The Sca-1 cell surface marker enriches for a prostate-regenerating cell subpopulation that can initiate prostate tumorigenesis

Sca-1 (stem cell antigen-1) enriches for murine prostate cells capable of regenerating tubular structures containing basal and luminal cell lineages in a dissociated cell prostate regeneration system. Sca-1(+) fractions are enriched for cells at the G(0) stage of the cell cycle, and Sca-1(+) cells cluster in the proximal region of prostatic tubules where replication-quiescent cells have been localized. Castration-induced enrichment for androgen-independent cells results in a concomitant enrichment for Sca-1(+) cells. Genetic perturbations of PTEN/AKT signaling in prostate-regenerating cells leads to the initiation of tumorigenesis, and cancer progression is associated with a dramatic increase in Sca-1(+) cells. Sca-1-enriched prostate-regenerating cells possess multiple stem/progenitor cell properties and can serve as targets for cancer initiation.

Communicating prostate cancer risk: what should we be telling our patients?

Until definitive evidence of the effectiveness of prostate cancer screening is available, most guidelines advocate that men make their own decisions about testing, after being fully informed. A man's perception of his personal risk is a key element in the decision-making process. In this decision-making, the current routine use of population risk estimates may be misleading. Risk estimates need to be relevant to the man making the choice. In particular, they should be age-specific and, where possible, include adjustments for known risk factors such as family history. As an example, although the population risk of lung cancer mortality is twice that of prostate cancer, for a non-smoking man with a family history of prostate cancer the direction of this comparison would be reversed. A man aged 50 diagnosed with prostate cancer has a greater likelihood (60%) of dying prematurely (before 80 years) from prostate cancer than a man diagnosed when aged 70 (38%). This can be attributed to the longer time available for the prostate cancer to progress, and the increased effect of competing causes of death among older men. This suggests that the oft-used statement "men are more likely to die with prostate cancer than from prostate cancer" is misleading, particularly for men diagnosed in their 50s or 60s. Decisions need to be made by men based on the best possible understanding of their personal vulnerability, and the individualisation of risk provides a more realistic appraisal of potential threat posed by the disease.

The propeptide mediates formation of stromal stores of PROMIC-1: role in determining prostate cancer outcome

The extracellular matrix (ECM) is a reservoir of cellular binding proteins and growth factors that are critical for normal cell behavior, and aberrations in the ECM invariably accompany malignancies such as prostate cancer. Carcinomas commonly overexpress macrophage inhibitory cytokine 1 (MIC-1), a proapoptotic and antitumorigenic transforming growth factor-beta superfamily cytokine. Here we show that MIC-1 is often secreted in an unprocessed propeptide containing form. It is variably processed intracellularly, with unprocessed forms being secreted from several tumor lines, including prostate carcinoma lines, PC-3 and LNCaP. Once secreted, only unprocessed proMIC-1 binds ECM, demonstrating for the first time the occurrence of extracellular stores of MIC-1. The propeptide mediates this association via its COOH-terminal 89 amino acids. Xenograft models bearing tumors secreting various engineered forms of MIC-1 show that the propeptide regulates the balance between ECM stores and circulating serum levels of mature MIC-1 in vivo. The absence of propeptide results in approximately 20-fold increase in serum MIC-1 levels. The significance of stromal MIC-1 stores was evaluated in prostate cancer tissue cores, which show major variation in stromal levels of MIC-1. Stromal MIC-1 levels are linked to prostate cancer outcome following radical prostatectomy, with decreasing stromal levels providing an important independent predictor of disease relapse. In low-grade localized prostate cancer (Gleason sum score < or = 6), the level of MIC-1 stromal stores was the best predictor of future relapse when compared with all other clinicopathologic variables. The secretion and ECM association of unprocessed proMIC-1 is likely to play a central role in modulating local bioavailability of MIC-1 which can affect patient outcome in prostate cancer and other epithelial tumors.

The E211 G>A Androgen Receptor Polymorphism Is Associated with a Decreased Risk of Metastatic Prostate Cancer and Androgenetic Alopecia

The androgen receptor (AR) gene encodes a transcription factor, which mediates androgen action in target tissues, including the prostate. Prostate cancer is androgen dependent, implicating AR in susceptibility to this male condition. Male pattern balding, androgenetic alopecia, has recently been associated with prostate cancer, suggesting shared androgen pathways. The CAG and GGC repeats in the AR have been studied extensively as markers of prostate cancer susceptibility, with inconclusive findings, whereas the AR-E211 G>A polymorphism has been associated with androgenetic alopecia. We assessed the repeat linked single nucleotide polymorphism as a marker of risk association in prostate cancer, including androgenetic alopecia, in an Australian population-based case-control study. In 815 prostate cancer cases and 719 controls, the proportion of A-allele carriers was the same in each group. Overall, there was no evidence for an association between the A allele and risk of prostate cancer, however, the proportion of A-allele carriers in metastatic prostate cancer (5%) was lower than in less advanced disease (16%, P = 0.03). The proportion of A-allele carriers was 24% in nonbald men but it was lower in men with vertex alopecia alone (13%, P = 0.001) or in combination with frontal alopecia (7%, P < 0.0001). This inverse association between the A allele and baldness was independent of prostate cancer status (P for interaction = 0.2). These results suggest that the AR-E211 A allele, in linkage with the functional repeat sequences, is associated with a lower risk of metastatic prostate cancer and a lower risk of alopecia.

Stromal-epithelial measurements of prostate cancer in native Japanese and Japanese-American men

We measured the histologic stromal and epithelial tissue components of the benign (normal) and malignant tissue compartments of Japanese-Americans (J-A) and native Japanese (NJ) men living in Japan. The patient cohort included 25 NJ men undergoing radical prostatectomy (RP) in Nagoya, Japan and 25 J-A (second or third generation US born). We conducted tissue image quantitation (in-house image software) of the stromal and epithelial compartments in malignant and adjacent normal tissue areas from a tissue microarray (TMA) selected from radical prostatectomy (RP) blocks. Stromal-epithelial (S-E) areas were determined using immunohistochemical stains for CAM-5.2 epithelial cytokeratin marker and the Masson trichrome stain to measure the stroma component. We observed differences in the volumes of normal and cancer epithelium and stroma within both the J-A and NJ study populations (P<0.01). Only the individual average cancer epithelium (CE) volume (JA=24.1 vs NJ=29.9) differed significantly between the NJ and J-A study populations (P=0.03). Consequently, the S-E ratio in NJ group was significantly different from that of J-A population (P=0.05). The decrease in S-E ratio noted in the malignant tissues of NJ prostate tissue may provide a biological marker for differentiation of the two groups and suggests a need for further investigations into the molecular basis for these histologic differences.

Peripheral T cell tolerance occurs early during spontaneous prostate cancer development and can be rescued by dendritic cell immunization

In the tumor-prone transgenic adenocarcinoma mouse prostate (TRAMP) mouse model we followed the fate of the immune response against the SV40 large T antigen (Tag) selectively expressed in the prostate epithelium during the endogenous transformation from normal cells to tumors. Young (5-7-week-old) male TRAMP mice, despite a dim and patchy expression of Tag overlapping foci of mouse prostate intraepithelial neoplasia, displayed a strong Tag-specific cytotoxic T lymphocyte (CTL) response after an intradermal injection of peptide-pulsed dendritic cells (DC). This response was weaker than the one found in vaccinated wild-type littermates, and was characterized by a reduced frequency and avidity of Tag-specific CTL. Early DC vaccination also subverted the profound state of peripheral tolerance typically found in TRAMP mice older than 9-10 weeks. The DC-induced CTL response indeed was still detectable in TRAMP mice of 16 weeks, and was associated with histology evidence of reduced disease progression. Our findings suggest that tumor antigens are handled as self antigens, and peripheral tolerance is associated with in situ antigen overexpression and cancer progression. Our data also support a relevant role for DC-based vaccines in controlling the induction of peripheral tolerance to tumor antigens.

Increased CD59 protein expression predicts a PSA relapse in patients after radical prostatectomy

BACKGROUND

Human protectin (CD59) is a regulator of complement activation that inhibits complement-mediated cell lysis, and thus might confer immune resistance to tumor cells. CD59 expression has been described in a variety of human malignancies, including breast cancer. Since a comprehensive investigation of CD59 expression in prostate cancer has not been conducted yet, we aimed to determine the significance of CD59 expression in prostate cancer.

METHODS

Eighty-six primary adenocarcinomas of the prostate were immunostained using a monoclonal CD59 antibody (clone MEM-43) and a standard detection system. The immunoreactivity of the tumor was evaluated as low versus high for statistical analysis. Additionally, CD59 mRNA levels were determined by real-time PCR in matched (tumor/normal) microdissected tissues from 26 cases.

RESULTS

Cytoplasmic CD59 immunoreactivity was found in epithelia of prostate cancer, prostatic intraepithelial neoplasia, benign hyperplasia, atrophic, and normal glands. High rates of CD59 expression were noted in 36% of prostate cancer cases and were significantly associated with tumor pT stage (P = 0.043), Gleason grade (P = 0.013) and earlier biochemical (PSA) relapse in Kaplan-Meier analysis (P = 0.0013). On RNA level, we found an upregulation in 19.2% (five cases), although the general rate of CD59 transcript was significantly lower in tumor tissue (P = 0.03).

CONCLUSION

CD59 protein is strongly expressed in 36% of adenocarcinomas of the prostate and and is associated with disease progression and adverse patient prognosis.

Hey1, a mediator of notch signaling, is an androgen receptor corepressor

Hey1 is a member of the basic helix-loop-helix-Orange family of transcriptional repressors that mediate Notch signaling. Here we show that transcription from androgen-dependent target genes is inhibited by Hey1 and that expression of a constitutively active form of Notch is capable of repressing transactivation by the endogenous androgen receptor (AR). Our results indicate that Hey1 functions as a corepressor for AF1 in the AR, providing a mechanism for cross talk between Notch and androgen-signaling pathways. Hey1 colocalizes with AR in the epithelia of patients with benign prostatic hyperplasia, where it is found in both the cytoplasm and the nucleus. In marked contrast, we demonstrate that Hey1 is excluded from the nucleus in most human prostate cancers, raising the possibility that an abnormal Hey1 subcellular distribution may have a role in the aberrant hormonal responses observed in prostate cancer.

Global hypomethylation is common in prostate cancer cells: a quantitative predictor for clinical outcome?

This study was designed to determine if cytological detection of 5-methylcytosine (5MC) was feasible on prostate tumor sections and to determine if levels of 5MC differed in malignant compared to normal prostate tissue. We further sought to see if 5MC levels correlated with any clinical outcome data. Thirty prostate tumor sections were obtained from patients who underwent radical prostatectomies from 1988 to 1995; these represented a mix of low to high grade tumors. Clinical data were maintained for each of these patients with a minimum of 7 years of follow up. Sections were stained with a commercially available antibody to 5MC and immunocytochemistry levels were subsequently quantified using a computer-assisted true-color imaging system. Tumor and benign regions of the same archived sections were compared, in addition to a series of 12 normal prostate samples. Prostate cancer cells exhibited a pronounced global decrease in methylation compared with benign and normal tissue. This was observed in 29 of 30 patients (96.7%) studied and densitometric scanning of methylation staining indicated that this value was quantifiable. Overall, higher methylation values were detected in men who had positive surgical margins and recurrent disease. These data suggest that loss of methylation is a feature of prostate cancer, and partial gain of methylation (presumably at promoters of specific genes) is associated with clinical outcome and is measurable using whole-cell assays.

Trefoil factor 3 is overexpressed in human prostate cancer

The trefoil factors are secreted peptides produced by normal intestinal mucosa. Members of the trefoil family are overexpressed in a variety of cancers and are associated with tumor invasion, resistance to apoptosis, and metastasis. Recent cDNA array analyses suggest that human intestinal trefoil factor 3 (TFF3) may be overexpressed in human prostate cancer. Immunohistochemistry was performed on a prostate cancer tissue microarray containing tumor tissue samples from 246 primary radical retropubic prostatectomy cases with antibodies specific for TFF3. Prostatic intraepithelial neoplasia (PIN), benign prostatic hyperplasia (BPH), and morphologically normal prostatic epithelium were represented on this array. Additionally, 18 metastatic lesions were also stained. Two independent pathologists scored the tissue arrays, with positive cases defined as those containing TFF3 staining in a majority of target cells within any spots representing the appropriate designated histology. Forty-two percent of 236 cases containing prostate cancer stained positive for TFF3, while only 10% of 145 cases containing normal tissue and 18% of 91 cases containing BPH, stained positive. Seven of 18 (39%) metastatic lesions analyzed stained positive. Although TFF3 expression correlates significantly with prostate cancer, TFF3 expression did not correlate with Gleason grade, tumor stage, or rate of recurrence. These studies validate that TFF3 is overexpressed in a subset of primary and metastic prostate cancers.

Exogenous Fibroblast Growth Factors Maintain Viability, Promote Proliferation, and Suppress GADD45α and GAS6 Transcript Content of Prostate Cancer Cells Genetically Modified to Lack Endogenous FGF-2

Understanding processes regulating prostate cancer cell survival is critical to management of advanced disease. We used prostate cancer cell transfectants genetically modified to be deficient in either endogenous fibroblast growth factor (FGF-1) or endogenous FGF-2 to examine FGF maintenance of transfectant survival and proliferation and FGF-2-regulated expression of transfectant growth arrest DNA damage (GADD) and growth arrest sequences (GAS) family genes (known modulators of cell cycle progression and survival) and the AS3 gene (an androgen-modulated effector of prostate cell proliferation). When propagated in the absence of exogenous FGFs, FGF-2-deficient transfectants undergo exponential death, whereas FGF-1-deficient transfectants proliferate. Exogenous FGF-1, FGF-2, FGF-7, or FGF-8 promote survival and proliferation of FGF-2-deficient transfectants and enhance FGF-1-deficient transfectant proliferation. Transfectants express FGF receptor FGFR1, FGFR2(IIIb), FGFR2(IIIc), and FGFR3 transcripts, findings consistent with the effects of exogenous FGFs. FGF-2-deficient transfectants express high levels of AS3, GADD45α, GADD45γ, GAS8, and GAS11 transcripts and moderate levels of GADD153, GAS2, GAS3, and GAS6 transcripts and lack demonstrable GAS1 or GAS5 transcripts. FGF withdrawal-mediated death of FGF-2-deficient transfectants did not significantly affect cell AS3, GADD153, GADD45γ, GAS2, GAS3, GAS7, GAS8, or GAS11 transcript content, whereas GADD45α and GAS6 transcript content was elevated. These studies establish that endogenous FGF-2 dominantly regulates prostate cancer cell survival and proliferation and that exogenous FGFs may assume this function in the absence of endogenous FGF-2. Additionally, we provide the first evidence that FGFs regulate prostate GADD45α and GAS6 transcript content. The latter observations suggest that GADD45α and GAS6 proteins may be effectors of processes that regulate prostate cancer cell survival. Additional studies are required to examine this possibility in detail.

Lesions predictive for prostate cancer in a screened population: first and second screening round findings

BACKGROUND

We evaluated the incidence of prostate cancer, high-grade prostatic intraepithelial neoplasia (PIN) and lesions suspicious for prostate cancer (LSPC) in sextant biopsies in two subsequent screening rounds at a 4-year interval and their predictive value for subsequent prostate cancer detection.

METHODS

In the Rotterdam section of the European Randomized Study of Screening for Prostate Cancer (ERSPC), 4,117 men underwent sextant biopsy in the 1st screening round. The 2nd round was performed at a 4-year interval and biopsies were taken in 1,840 men.

RESULTS

The incidences of prostate cancer, LSPC and PIN in the 1st, respectively 2nd round were 24.6, resp. 19.9% (P = 0.001), 2.7, resp. 2.8% and 0.8, resp. 2.5% (P < 0.0001). Prostate cancer incidence after repeat biopsy for LSPC in the 1st, respectively 2nd round was 36.7 and 17.0%, and after repeat biopsy for PIN 13.3% in both rounds, respectively. Men with a benign biopsy in the 1st round had a significantly lower prostate cancer incidence in the 2nd round compared to men who did not undergo biopsy in the 1st round (10.7 vs. 22.7%, P < 0.0001).

CONCLUSIONS

The decrease of prostate cancer detection in the 2nd round was associated with an increase in the incidence of PIN. Strikingly, LSPC diagnosed during the 1st round, but not during the 2nd round were predictive for prostate cancer, while isolated PIN was never predictive for prostate cancer. PIN should not be an indication for repeat biopsy in a screening population. Importantly a 1st round benign biopsy outcome proved to be a negative predictor of subsequent prostate cancer detection.

Prostate carcinogenesis and inflammation: emerging insights

Prostate cancer remains a significant health concern for men throughout the world. Recently, there has developed an expanding multidisciplinary body of literature suggesting a link between chronic inflammation and prostate cancer. In support of this hypothesis, population studies have found an increased relative risk of prostate cancer in men with a prior history of certain sexually transmitted infections or prostatitis. Furthermore, genetic epidemiological data have implicated germline variants of several genes associated with the immunological aspects of inflammation in modulating prostate cancer risk. The molecular pathogenesis of prostate cancer has been characterized by somatic alterations of genes involved in defenses against inflammatory damage and in tissue recovery. A novel putative prostate cancer precursor lesion, proliferative inflammatory atrophy, which shares some molecular traits with prostate intraepithelial neoplasia and prostate cancer, has been characterized. Here, we review the evidence associating chronic inflammation and prostate cancer and consider a number of animal models of prostate inflammation that should allow the elucidation of the mechanisms by which prostatic inflammation could lead to the initiation and progression of prostate cancer. These emerging insights into chronic inflammation in the etiology of prostate carcinogenesis hold the promise of spawning new diagnostic and therapeutic modalities for men with prostate cancer.

Characteristics of insignificant clinical T1c prostate tumors

BACKGROUND

The authors examined the cases of men who had undergone radical prostatectomy for low-volume clinical T1c prostate carcinoma that was judged to be 'insignificant' on the basis of previously established preoperative clinicopathologic parameters. Pathologic findings subsequently were analyzed for correlations with extent of disease in an attempt to validate the contemporary usefulness of existing parameters for predicting the 'significance' of prostate tumors.

METHODS

A series of 237 men who had undergone radical prostatectomy for T1c disease between December 2000 and August 2003 was evaluated. Insignificant prostate carcinoma as assessed on biopsy was defined according to the 1994 Epstein criteria, which were as follows: prostate-specific antigen density < 0.15 ng/mL, Gleason score < or = 6, fewer than 3 cores containing prostate carcinoma, and < or = 50% involvement of any core with prostate carcinoma. Postsurgical pathologic findings were analyzed for potential correlations with the Epstein criteria.

RESULTS

According to the Epstein needle biopsy criteria, organ-confined prostate carcinoma was detected in 91.6% of all patients, whereas the remaining 8.4% of patients were found to have non-organ-confined disease. Comparison of pathologic findings and Epstein biopsy criteria revealed that alteration of the original criteria did not improve the detection of non-organ-confined prostate carcinoma.

CONCLUSIONS

The findings made in the current study suggest that the majority of patients with T1c prostate carcinoma have insignificant disease. Furthermore, it was found that the Epstein criteria for identifying insignificant prostate carcinoma remained a useful tool in the making of treatment-related decisions.

Molecular features of the transition from prostatic intraepithelial neoplasia (PIN) to prostate cancer: genome-wide gene-expression profiles of prostate cancers and PINs

To characterize the molecular feature in prostate carcinogenesis and the putative transition from prostatic intraepithelial neoplasia (PIN) to invasive prostate cancer (PC), we analyzed gene-expression profiles of 20 PCs and 10 high-grade PINs with a cDNA microarray representing 23,040 genes. Considering the histological heterogeneity of PCs and the minimal nature of PIN lesions, we applied laser microbeam microdissection to purify populations of PC and PIN cells, and then compared their expression profiles with those of corresponding normal prostatic epithelium also purified by laser microbeam microdissection. A hierarchical clustering analysis separated the PC group from the PIN group, except for three tumors that were morphologically defined as one very-high-grade PIN and two low-grade PCs, suggesting that PINs and PCs share some molecular features and supporting the hypothesis of PIN-to-PC transition. On the basis of this hypothesis, we identified 21 up-regulated genes and 63 down-regulated genes commonly in PINs and PCs compared with normal epithelium, which were considered to be involved in the presumably early stage of prostatic carcinogenesis. They included AMACR, OR51E2, RODH, and SMS. Furthermore, we identified 41 up-regulated genes and 98 down-regulated genes in the transition from PINs to PCs; those altered genes, such as POV1, CDKN2C, EPHA4, APOD, FASN, ITGB2, LAMB2, PLAU, and TIMP1, included elements that are likely to be involved in cell adhesion or the motility of invasive PC cells. The down-regulation of EPHA4 by small interfering RNA in PC cells lead to attenuation of PC cell viability. These data provide clues to the molecular mechanisms underlying prostatic carcinogenesis, and suggest candidate genes the products of which might serve as molecular targets for the prevention and treatment of PC.

Basal prostate epithelial cells stimulate the migration of prostate cancer cells

Carcinoma cells in PIN are situated above a layer of basal epithelial cells, which shield the tumor cells from stimulation by factors from the prostate stroma. During progression to invasive carcinoma, the basal cell layer becomes disrupted and tumor cells adhere to the basement membrane. The close proximity of basal epithelial cells to tumor cells in the early stages of prostate oncogenesis raises the possibility that basal epithelial cells participate in tumor cell invasion. Here, we investigated the migration-promoting activity of secreted factors from basal epithelial cells on BPH-1 cells, which we used as an in vitro model of preinvasive prostate cancer cells. We showed that the conditioned medium of basal epithelial cells (PEC-CM) contains adhesion proteins and chemotactic factors that stimulate adhesion, planar polarization, migration, and phosphorylation of Akt and that LY294002 and Wortmannin partially inhibit PEC-CM-triggered migration. We identified laminin-5 as a major migration-stimulating protein for BPH-1 cells in PEC-CM. Laminin-5 induced migration is completely inhibited by LY294002 or Wortmannin. In addition, antibody-depletion of laminin-5 from PEC-CM significantly diminishes the migration of BPH-1 cells. These results demonstrated, that laminin-5 is secreted by basal prostate epithelial cells in vivo and in vitro and stimulates migration of BPH-1 cells through a PI3-kinase dependent mechanism. Altogether, the possibility that basal epithelial cells assist in the invasion of in situ carcinoma cells is supported by the results from our in vitro system.

Cancer de la prostate. Épidémiologie. Facteurs de risques. Anatomopathologie

Prostate cancer (prostate adenocarcinoma) has become an important concern in terms of public health these past fifteen years; recent French epidemiological data revealed 10,104 deaths due to this disease in 2000. The two main factors involved are the serum prostatic specific antigen (PSA), routinely used since late 1980's and which allows early diagnosis (before symptom onset), and the lengthened duration of life. Such cancer is rare before the age of 50, but its frequency increases with age, making it the most frequent type of cancer in French men. Although the aetiology of this disease is unknown, the ethnic origin, and a familial history of prostate or breast cancer are known risk factors. Predisposing genes to such hereditary types remain to be identified. Other genetic factors (polymorphisms), combined with environmental factors such as nutrition, have been incriminated, which is likely to explain the geographical variations of this affection. At the molecular level, the mechanisms involved in the tumoral initiation and progression remain unclear. Various genetic alterations have been identified among the genome of cancerous cells, at various stages of the affection: intraepithelial neoplasia, localized, locally advanced, metastatic or hormone refractory stage -, hormonal escape). However, the precise sequence and nature of the complex molecular events remain to be determined prior to their routine utilisation in the determination of subjects at risk, or as prognostic factors, and even as therapeutic targets. The anatomopathology is a key for the diagnosis. Intraepithelial neoplasia is the pre-cancerous lesion observed in most adenocarcinomas; these are localized in the peripheral part of the prostate gland in 70% of the cases. Gleason's classification is the current gold standard for the determination of tumoral aggressiveness and categorisation of the adenocarcinomas which are basically heterogeneous (coexistence of tumors cells with different degrees of differenciation in the same tumor). This anatomopathological classification allows distinguishing the tumours in terms of potential progressiveness and prognosis, and hence, to orientate the therapeutic strategy in case of localised or locally advanced prostate cancer.

Future opportunities for the diagnosis and treatment of prostate cancer

Despite recent advances, current diagnostic tests and treatment of prostate cancer have limitations. In the last few years, numerous biomolecules have been investigated with the aim of improving diagnosis, including kallikrein-like proteases, growth factors and neuroendocrine markers. Analysis of susceptibility genes has also been a focus of attention. Extensive research into new therapeutic approaches is also underway, including targeting angiogenesis, immune regulation and stromal-epithelial interactions. Gene therapy, gene chip technology and proteomics have emerged as promising innovations. The host of novel diagnostic markers and therapies require appropriate validation, both phenotypical and functional. A further consideration is the need to re-evaluate clinical trial design and end points to facilitate progression of promising targets through the clinical trial process. Overall, the outlook for the treatment of prostate cancer looks promising, with any advances likely to require both a multimodal and multidisciplinary approach.

ATM polymorphisms as risk factors for prostate cancer development

The risk of prostate cancer is known to be elevated in carriers of germline mutations in BRCA2, and possibly also in carriers of BRCA1 and CHEK2 mutations. These genes are components of the ATM-dependent DNA damage signalling pathways. To evaluate the hypothesis that variants in ATM itself might be associated with prostate cancer risk, we genotyped five ATM variants in DNA from 637 prostate cancer patients and 445 controls with no family history of cancer. No significant differences in the frequency of the variant alleles at 5557G>A (D1853N), 5558A>T (D1853V), ivs38-8t>c and ivs38-15g>c were found between the cases and controls. The 3161G (P1054R) variant allele was, however, significantly associated with an increased risk of developing prostate cancer (any G vs CC OR 2.13, 95% CI 1.17–3.87, P=0.016). A lymphoblastoid cell line carrying both the 3161G and the 2572C (858L) variant in the homozygote state shows a cell cycle progression profile after exposure to ionising radiation that is significantly different to that seen in cell lines carrying a wild-type ATM gene. These results provide evidence that the presence of common variants in the ATM gene, may confer an altered cellular phenotype, and that the ATM 3161C>G variant might be associated with prostate cancer risk.

Activation of signal transducer and activator of transcription 5 in human prostate cancer is associated with high histological grade

We have recently identified signal transducer and activator of transcription 5 (Stat5) as a critical survival factor for prostate cancer cells. We now report that activation of Stat5 is associated with high histological grade of human prostate cancer. Specifically, immunohistochemical analysis demonstrated a strong positive correlation with activation of Stat5 and high Gleason score in 114 human prostate cancers. To investigate the mechanisms underlying constitutive activation of Stat5 in prostate cancer, a dominant-negative mutant of Janus kinase 2 (Jak2) was delivered by adenovirus to CWR22Rv cells. Dominant-negative-Jak2 effectively blocked the activation of Stat5 whereas wild-type Jak2 enhanced activation, indicating that Jak2 is the main kinase that phosphorylates Stat5 in human prostate cancer cells. A ligand-induced mechanism for activation of Stat5 in prostate cancer was suggested by the ability of prolactin (Prl) to stimulate activation of both Jak2 and Stat5 in CWR22Rv human prostate cancer cells and in CWR22Rv xenograft tumors. In addition, Prl restored constitutive activation of Stat5 in five of six human prostate cancer specimens in ex vivo long-term organ cultures. Finally, Prl protein was locally expressed in the epithelium of 54% of 80 human prostate cancer specimens with positive correlation with high Gleason scores and activation of Stat5. In conclusion, our data indicate that increased activation of Stat5 was associated with more biologically aggressive behavior of prostate cancer. The results further suggest that Jak2 is the principal Stat5 tyrosine kinase in human prostate cancer, possibly activated by autocrine/paracrine Prl.

Inhibition of prostate cancer proliferation by interference with SONIC HEDGEHOG-GLI1 signaling

Prostate cancer is the most common solid tumor in men, and it shares with all cancers the hallmark of elevated, nonhomeostatic cell proliferation. Here we have tested the hypothesis that the SONIC HEDGEHOG (SHH)-GLI signaling pathway is implicated in prostate cancer. We report expression of SHH-GLI pathway components in adult human prostate cancer, often with enhanced levels in tumors versus normal prostatic epithelia. Blocking the pathway with cyclopamine or anti-SHH antibodies inhibits the proliferation of GLI1+/PSA+ primary prostate tumor cultures. Inversely, SHH can potentiate tumor cell proliferation, suggesting that autocrine signaling may often sustain tumor growth. In addition, pathway blockade in three metastatic prostate cancer cell lines with cyclopamine or through GLI1 RNA interference leads to inhibition of cell proliferation, suggesting cell-autonomous pathway activation at different levels and showing an essential role for GLI1 in human cells. Our data demonstrate the dependence of prostate cancer on SHH-GLI function and suggest a novel therapeutic approach.

Up-regulation of hypoxia-inducible factor 1alpha is an early event in prostate carcinogenesis

Hypoxia-inducible factor 1 (HIF-1) activates the transcription of genes encoding glucose transporters, glycolytic enzymes, and vascular endothelial growth factor (VEGF). HIF-1alpha is a major subunit of HIF-1 heterodimer. In this study, an immunohistochemical analysis of HIF-1alpha was focused on clinical specimens containing high-grade prostate intraepithelial neoplasia lesions since high-grade prostate intraepithelial neoplasia is considered the precursor of a majority of invasive prostate adenocarcinoma and presents the increased activity of angiogenesis. HIF-1alpha was up-regulated in 11 of 14 high-grade prostate intraepithelial neoplasia lesions identified in a total 10 prostate biopsies relative to the respective normal epithelium, stromal cells, and benign prostatic hyperplasia (BPH). Moreover, up-regulation of HIF-1alpha in adjacent prostate cancer lesions was more enhanced than in high-grade prostate intraepithelial neoplasia. The results suggest that up-regulation of HIF-1alpha is an early event in prostate carcinogenesis, and that HIF-1alpha may become a potential target for prostate cancer prevention and a surrogate biomarker for monitoring pre-malignant lesions of the prostate.