Perspective: prostate cancer susceptibility genes

Role of Genetic Polymorphisms in the Development and Prognosis of Sporadic and Familial Prostate Cancer

Backgrounds

Our aim was to evaluate the role of 20 genetic polymorphisms in the development and prognosis of sporadic and familial PC. A case-control study of 185 patients who underwent radical prostatectomy from 1997 to 2011. These patients were divided into two groups based on their family history. Gleason grade, PSA value and pathological TNM 2002 stage were used as prognostic factors. Blood samples from 70 men without PC were used as controls. The SNPs were genotyped using a TaqMan^® SNP Genotyping Assay Kit.

Results

Considering susceptibility, the polymorphic allele in the SNP rs2660753 on chromosome 3 was significantly more prevalent in controls (p = 0.01). For familial clustering, the polymorphic homozygote genotype of the SNP rs7931342 was five times more frequent in patients with familial PC compared to sporadic PC (p = 0.01). Regarding the SNP 1447295, the polymorphic homozygote genotype was more prevalent in patients with organ-confined PC (p = 0.05), and most importantly, the polymorphic allele occurred more frequently in patients without biochemical recurrence (p = 0.01). Kaplan-Meier analysis showed a median biochemical recurrence free survival of 124.2 compared to 85.6 months for patients with the wild-type allele (p = 0.007).

Conclusion

Our findings provide the evidence for the association of 20 recently highlighted SNPs and their susceptibility, familial clustering, staging, Gleason score and biochemical recurrence of PC. We believe that the association between these SNPs and PC may contribute to the development of alternative tools that can facilitate the early detection and prognosis of this disease.

Nanotherapy silencing the interleukin-8 gene produces regression of prostate cancer by inhibition of angiogenesis

Interleukin-8 (IL-8) is a pro-angiogenic cytokine associated with aggressive prostate cancer (CaP). We detected high levels of IL-8 in sera from patients with CaP compared with healthy controls and patients with benign prostatic hypertrophy. This study examines the role of IL-8 in the pathogenesis of metastatic prostate cancer. We developed a biocompatible, cationic polylactide (CPLA) nanocarrier to complex with and efficiently deliver IL-8 small interfering RNA (siRNA) to CaP cells in vitro and in vivo. CPLA IL-8 siRNA nanocomplexes (nanoplexes) protect siRNA from rapid degradation, are non-toxic, have a prolonged lifetime in circulation, and their net positive charge facilitates penetration of cell membranes and subsequent intracellular trafficking. Administration of CPLA IL-8 siRNA nanoplexes to immunodeficient mice bearing human CaP tumours produced significant antitumour activities with no adverse effects. Systemic (intravenous) or local intra-tumour administration of IL-8 siRNA nanoplexes resulted in significant inhibition of CaP growth. Magnetic resonance imaging and ultrasonography of experimental animals demonstrated reduction of tumour perfusion in vivo following nanoplex treatment. Staining of tumour sections for CD31 confirmed significant damage to tumour neovasculature after nanoplex therapy. These studies demonstrate the efficacy of IL-8 siRNA nanotherapy for advanced, treatment-resistant human CaP.

Identification of Two Novel HOXB13 Germline Mutations in Portuguese Prostate Cancer Patients

The HOXB13 germline variant G84E (rs138213197) was recently described in men of European descent, with the highest prevalence in Northern Europe. The G84E mutation has not been found in patients of African or Asian ancestry, which may carry other HOXB13 variants, indicating allelic heterogeneity depending on the population. In order to gain insight into the full scope of coding HOXB13 mutations in Portuguese prostate cancer patients, we decided to sequence the entire coding region of the HOXB13 gene in 462 early-onset or familial/hereditary cases. Additionally, we searched for somatic HOXB13 mutations in 178 prostate carcinomas to evaluate their prevalence in prostate carcinogenesis. Three different patients were found to carry in their germline DNA two novel missense variants, which were not identified in 132 control subjects. Both variants are predicted to be deleterious by different in silico tools. No somatic mutations were found. These findings further support the hypothesis that different rare HOXB13 mutations may be found in different ethnic groups. Detection of mutations predisposing to prostate cancer may require re-sequencing rather than genotyping, as appropriate to the population under investigation.

High prevalence of GPRC5A germline mutations in BRCA1-mutant breast cancer patients

In a search for new breast cancer (BC) predisposing genes, we performed a whole exome sequencing analysis using six patient samples of familial BC and identified a germline inactivating mutation c.183delG [p. Arg61fs] in an orphan G protein-coupled receptor GPRC5A. An extended case-control study revealed a tenfold enrichment for this mutation in BC patients carrying the 5382insC allele of BRCA1, the major founder mutation in the Russian population, compared to wild-type BRCA1 BC cases [6/117 (5.1%) vs. 8/1578 (0.5%), p = 0.0002]. In mammary tumors (n = 60), the mRNA expression of GPRC5A significantly correlated with that of BRCA1 (p = 0.00018). In addition, the amount of GPRC5A transcript was significantly lower in BC obtained from BRCA1 mutation carriers (n = 17) compared to noncarriers (n = 93) (p = 0.026). Accordingly, a siRNA-mediated knockdown of either BRCA1 or GPRC5A in the MDA-MB-231 human BC cell line reduced expression of GPRC5A or BRCA1, respectively. Knockdown of GPRC5A also attenuated radiation-induced BRCA1- and RAD51-containing nuclear DNA repair foci. Taken together, these data suggest that GPRC5A is a modifier of BC risk in BRCA1 mutation carriers and reveals a functional interaction of these genes.

The biology and natural history of prostate cancer: a short introduction

This chapter aims to serve as a quick glance outlining an overall picture of mainstream thoughts, and to serve as a point of departure for more thorough discussions. The introduction of PSA testing has immensely complicated research in prostate cancer epidemiology and biology and added new clinical and biological domains. As for many cancers, age and ethnic origin are the strongest known risk factors. While migrant studies imply that environment and/or personal life style is important, epidemiological studies have failed to establish any strong leads. Despite the known androgen dependence of prostate cancer, there is little to support that circulating levels of androgens, estrogens or 5-alpha-reductase are associated with risk of developing the disease. However, a consistent finding is a positive association with levels of Insulin-like Growth Factor-1 (IGF-1). Prostate cancer is one of the cancers most strongly related to inherited susceptibility, even when taking into account that family history of prostate cancer triggers PSA testing among relatives. A number of somatic genetic alterations (amplifications, deletions, point mutations, translocations) are associated with prostate cancer risk. Findings for alterations in FASN, HPN, AMACR and MYC have been fairly consistent. Recent research shows that the notion of "hormone-independent prostate cancer" has to be revised: most prostate cancers remain dependent on androgen receptor signalling also after progression despite traditional androgen deprivation therapy. Traditional markers of stage and type of disease still play a major role for prognostication and treatment decisions. Prostate cancer is one of the few cancers where patients have been recommended watchful waiting or active surveillance. This provides opportunities for studies of natural history of the disease. The understanding of prostate cancer aetiology and natural history has progressed slowly. However, the current situation is positively challenging and opens up possibilities for fruitful research.

No evidence of XMRV in prostate cancer cohorts in the Midwestern United States

Background

Xenotropic murine leukemia virus (MLV)-related virus (XMRV) was initially identified in prostate cancer (PCa) tissue, particularly in the prostatic stromal fibroblasts, of patients homozygous for the RNASEL R462Q mutation. A subsequent study reported XMRV antigens in malignant prostatic epithelium and association of XMRV infection with PCa, especially higher-grade tumors, independently of the RNASEL polymorphism. Further studies showed high prevalence of XMRV or related MLV sequences in chronic fatigue syndrome patients (CFS), while others found no, or low, prevalence of XMRV in a variety of diseases including PCa or CFS. Thus, the etiological link between XMRV and human disease remains elusive. To address the association between XMRV infection and PCa, we have tested prostate tissues and human sera for the presence of viral DNA, viral antigens and anti-XMRV antibodies.

Results

Real-time PCR analysis of 110 PCa (Gleason scores >4) and 40 benign and normal prostate tissues identified six positive samples (5 PCa and 1 non-PCa). No statistical link was observed between the presence of proviral DNA and PCa, PCa grades, and the RNASEL R462Q mutation. The amplified viral sequences were distantly related to XMRV, but nearly identical to endogenous MLV sequences in mice. The PCR positive samples were also positive for mouse mitochondrial DNA by nested PCR, suggesting contamination of the samples with mouse DNA. Immuno-histochemistry (IHC) with an anti-XMRV antibody, but not an anti-MLV antibody that recognizes XMRV, sporadically identified antigen-positive cells in prostatic epithelium, irrespectively of the status of viral DNA detection. No serum (159 PCa and 201 age-matched controls) showed strong neutralization of XMRV infection at 1:10 dilution.

Conclusion

The lack of XMRV sequences or strong anti-XMRV neutralizing antibodies indicates no or very low prevalence of XMRV in our cohorts. We conclude that real-time PCR- and IHC-positive samples were due to laboratory contamination and non-specific immune reactions, respectively.

Angiotensin-converting enzyme insertion/deletion and angiotensin type 1 receptor A1166C polymorphisms as genetic risk factors in benign prostatic hyperplasia and prostate cancer

INTRODUCTION

Prostate cancer is one of the most common malignant neoplasias in developed countries. In 2003, 6,536 new cases and 4,602 related deaths were reported in Mexico. The renin-angiotensin system has been shown to play a role in prostate cancer pathology. Two previous studies investigated the association of prostate cancer with the insertion/deletion (I/D) polymorphism in the angiotensin-converting enzyme (ACE) gene; both studies reported an association between prostate cancer and the DD genotype. The present study was aimed at searching for an association of prostate cancer and benign prostatic hyperplasia with the I/D polymorphism in the ACE gene and the A1166C polymorphism in the angiotensin type 1 receptor (AGT1R) gene and at comparing allele frequencies between both groups and the general population.

MATERIALS AND METHODS

DNA was extracted from 20 samples from individuals with a prostate cancer diagnosis and from 20 samples from individuals with a benign prostatic hyperplasia diagnosis. Genotyping was performed by PCR-RFLP analysis. Polymorphism frequency results obtained for the test groups were compared with the frequencies in 66 individuals from the general population, which were previously obtained at the same molecular medicine laboratory in the context of other studies.

RESULTS

The comparative analysis of the three groups revealed significant differences for allele frequencies in the two genes in patients groups (prostate cancer and benign prostatic hyperplasia) versus the general population. The D allele in the ACE gene was closely associated with a significant higher risk of developing both benign prostatic hyperplasia (odds ratio [OR]=21.87; 95% confidence interval [CI]=2.314-206.479) or prostate cancer (OR=31.66; 95% CI=0.091-1.272), and the AGT1R A1166 allele in the homozygote state was identified as a risk genotype for benign prostatic hyperplasia (OR=56.07).

CONCLUSIONS

Genotypes in ACE and AGT1R polymorphisms could be considered as genetic risk markers for benign prostatic hyperplasia or prostate cancer.

Two loci controlling susceptibility to radiation-induced lymphomagenesis on mouse chromosome 4: cdkn2a, a candidate for one locus, and a novel locus distinct from cdkn2a

BALB/c mice are sensitive to radiation-induced lymphomagenesis, while STS mice are resistant. Using 219 [(BALB/c x STS)F(1) x BALB/c] (N2C) and 197 [(BALB/c x STS)F(1) x STS] (N2S) animals, we performed a genome-wide search for loci controlling susceptibility to lymphomagenesis induced by radiation. Association of markers with the survival of animals was analyzed by the log rank test. For N2C mice, a significant correlation was detected, with four markers on the proximal to mid portion of chromosome 4: D4Mit302 and D4Mit255, P = 0.0075; D4Mit17, P = 0.034; and D4Mit86, P = 0.048. On the other hand, no significant linkage was detected in N2S mice. We analyzed BALB/c mice congenic for the STS allele in different regions of chromosome 4 and identified a locus with a conspicuous effect on survival located within a 7-Mb region between D4Mit302 and D4Mit144, where BALB/c mice harbor hypomorphic variant alleles of the tumor suppressor gene Cdkn2a, which encodes the cyclin-dependent kinase inhibitor protein p16INK4a. Using pooled F(2) intercrosses between the BALB/c and congenic lines carrying the STS allele near D4Mit17, but not in the range from D4Mit302 to D4Mit144, we assigned the second locus to an 11.4-Mb region in the vicinity of D4Mit17. Although Cdkn2a is a likely candidate for the locus controlling susceptibility to lymphomagenesis on chromosome 4, a novel tumor susceptibility gene different from Cdkn2a exists near the primary locus.

Xenotropic murine leukemia virus-related virus is susceptible to AZT

The xenotropic murine leukemia virus-related virus (XMRV) is a human retrovirus, recently isolated from tissues of prostate cancer patients with impaired RNase L activity. In this study, we evaluated 10 licensed anti-HIV-1 compounds for their activity against XMRV, including protease inhibitors (PI), nucleoside reverse transcriptase (RT) inhibitors (NRTI), non-nucleoside RT inhibitors (NNRTI) and an integrase inhibitor. No PI affected XMRV production; even high concentrations of Ritonavir failed to inhibit the maturation of XMRV Gag polyproteins. Among the NRTI, NNRTI and integrase inhibitors used in this study, only AZT blocked XMRV infection and replication through inhibition of viral reverse transcription. This sensitivity of XMRV to AZT may be explained by the modest homology in the motif D sequences of HIV-1 and XMRV reverse transcriptases. If XMRV becomes established as an etiological agent for prostate cancer or other diseases, AZT may be useful for preventing or treating XMRV infections in humans.

Expression profile of microRNAs in c-Myc induced mouse mammary tumors

c-Myc is a transcription factor overexpression of which induces mammary cancer in transgenic mice. To explore whether certain microRNAs (mirRNA) mediate c-Myc induced mammary carcinogenesis, we studied mirRNA expression profile in mammary tumors developed from MMTV-c-myc transgenic mice, and found 50 and 59 mirRNAs showing increased and decreased expression, respectively, compared with lactating mammary glands of wild type mice. Twenty-four of these mirRNAs could be grouped into eight clusters because they had the same chromosomal localizations and might be processed from the same primary RNA transcripts. The increased expression of mir-20a, mir-20b, and mir-9 as well as decreased expression of mir-222 were verified by RT-PCR, real-time RT-PCR, and cDNA sequencing. Moreover, we fortuitously identified a novel non-coding RNA, the level of which was decreased in proliferating mammary glands of MMTV-c-myc mice was further decreased to undetectable level in the mammary tumors. Sequencing of this novel RNA revealed that it was transcribed from a region of mouse chromosome 19 that harbored the metastasis associated lung adenocarcinoma transcript-1 (Malat-1), a non-protein-coding gene. These results suggest that certain mirRNAs and the chromosome 19 derived non-coding RNAs may mediate c-myc induced mammary carcinogenesis.

Tagging SNPs in the kallikrein genes 3 and 2 on 19q13 and their associations with prostate cancer in men of European origin

Two of the classical kallikrein genes KLK3 and KLK2 on 19q13.4 are plausible candidates in prostate cancer susceptibility. They are expressed almost exclusively in prostate tissue. We have performed a comprehensive analysis of association of variants in these two genes with prostate cancer among men of European descent using a tagging SNP approach. Thirteen SNPs selected from the HapMap database were analyzed in a sample of 596 histologically verified prostate cancer cases and 567 ethnically matched controls. Five SNPs showed significant association at single marker level. Linkage disequilibrium (LD) analysis revealed four LD blocks. We performed a haplotype analysis within each LD block. A major haplotype in block 1 that contains the first two significantly associated SNPs was significantly underrepresented in the prostate cancer cases; a second haplotype in block 3 also showed significant frequency differences between cases and controls. Four of the studied SNPs show positive associations with serum PSA levels. A structure analysis revealed no population stratification in our samples that could have confounded the association results. These findings suggest a plausible role of kallikrein gene variants in the etiology of prostate cancer among men of European ancestry.

Loss of TP53 in sarcomas with 17p12~p11 gain. A fine-resolution oligonucleotide array comparative genomic hybridization study

The amplification or gain of the p-arm of chromosome 17 is common in sarcomas, suggesting its role in carcinogenesis. Here, we report the architectural structure and targets of 17p aberrations commonly shared by osteosarcoma (OS), leiomyosarcoma (LMS) and malignant fibrous histiocytoma (MFH) of soft tissue. Two low-grade and two high-grade soft tissue LMS, three OS, and two MFH samples were studied using fine-resolution oligonucleotide-based microarray comparative genomic hybridization. Eight of the nine samples showed a loss of 17pter-->p13, the locus of tumor suppressor TP53 preceding the amplified area 17p12-->p11.2. The size and detailed architecture of the amplified region of 17p differed between the studied sarcoma entities. OS and high-grade LMS showed similar complex patterns of discontinuous amplifications with regions of gain in between. MFH and low-grade LMS showed continuous regions of gains and amplifications. Precise boundaries of the lost or gained regions were determined, and in addition to the previously suggested targets of the region, ELAC and FLCN were amplified in all the sarcoma entities.

Botulinum-A toxin: an exciting new treatment option for prostatic disease

Recently, botulinum neurotoxin type A (BoNT-A) application in the lower urinary tract has been extended to prostate disorders and we would like to review the literature on the mechanisms of action and clinical efficacy of BoNT-A treatment in the prostate. The information was gathered from MEDLINE, abstracts from recent urological meetings and from personal experience. BoNT has demonstrated promising preliminary results for male prostatic disease and translational research suggests a novel mechanism of action of BoNT in the prostate. It is important to remember that the application of BoNT in the prostate is not approved by the regulatory agencies and caution should be applied until larger randomised clinical studies are completed.

Epigenetics of prostate cancer: beyond DNA methylation

Epigenetic mechanisms permit the stable inheritance of cellular properties without changes in DNA sequence or amount. In prostate carcinoma, epigenetic mechanisms are essential for development and progression, complementing, amplifying and diversifying genetic alterations. DNA hypermethylation affects at least 30 individual genes, while repetitive sequences including retrotransposons and selected genes become hypomethylated. Hypermethylation of several genes occurs in a coordinate manner early in carcinogenesis and can be exploited for cancer detection, whereas hypomethylation and further hypermethylation events are associated with progression. DNA methylation alterations interact with changes in chromatin proteins. Prominent alterations at this level include altered patterns of histone modification, increased expression of the EZH2 polycomb histone methyltransferase, and changes in transcriptional corepressors and coactivators. These changes may make prostate carcinoma particularly susceptible to drugs targeting chromatin and DNA modifications. They relate to crucial alterations in a network of transcription factors comprising ETS family proteins, the androgen receptor, NKX3.1, KLF, and HOXB13 homeobox proteins. This network controls differentiation and proliferation of prostate epithelial cells integrating signals from hormones, growth factors and cell adhesion proteins that are likewise distorted in prostate cancer. As a consequence, prostate carcinoma cells appear to be locked into an aberrant state, characterized by continued proliferation of largely differentiated cells. Accordingly, stem cell characteristics of prostate cancer cells appear to be secondarily acquired. The aberrant differentiation state of prostate carcinoma cells also results in distorted mutual interactions between epithelial and stromal cells in the tumor that promote tumor growth, invasion, and metastasis.

Variants in the HEPSIN gene are associated with prostate cancer in men of European origin

There is considerable evidence that genetic factors are involved in prostate cancer susceptibility. We have studied the association of 11 single nucleotide polymorphisms (SNPs) in the HEPSIN gene (HPN) with prostate cancer in men of European ancestry. HPN is a likely candidate in prostate cancer susceptibility, as it encodes a transmembrane cell surface serum protease, which is overexpressed in prostate cancer; HPN is also located on 19q11-q13.2, where linkage is found with prostate cancer susceptibility. In this case-control association study (590 men with histologically verified prostate cancer and 576 unrelated controls, all of European descent), we find significant allele frequency differences between cases and controls at five SNPs that are located contiguously within the gene. A major 11-locus haplotype is significantly associated, which provides further support that HPN is a potentially important candidate gene involved in prostate cancer susceptibility. Association of one of the SNPs with Gleason score is also suggestive of a plausible role of HPN in tumor aggressiveness.

Managing metastatic prostate cancer

Prostate cancer is one of the most commonly diagnosed malignancies in the west. Most patients with metastatic or recurrent prostate cancer initially respond to androgen deprivation therapy, but almost all eventually progress. This review will focus on current treatment options for metastatic prostate cancer, with a focus on hormonal therapies, chemotherapy and treatment of bony disease, along with biological and targeted therapy.

Molecular biology of the 3beta-hydroxysteroid dehydrogenase/delta5-delta4 isomerase gene family

The 3beta-hydroxysteroid dehydrogenase/Delta(5)-Delta(4) isomerase (3beta-HSD) isoenzymes are responsible for the oxidation and isomerization of Delta(5)-3beta-hydroxysteroid precursors into Delta(4)-ketosteroids, thus catalyzing an essential step in the formation of all classes of active steroid hormones. In humans, expression of the type I isoenzyme accounts for the 3beta-HSD activity found in placenta and peripheral tissues, whereas the type II 3beta-HSD isoenzyme is predominantly expressed in the adrenal gland, ovary, and testis, and its deficiency is responsible for a rare form of congenital adrenal hyperplasia. Phylogeny analyses of the 3beta-HSD gene family strongly suggest that the need for different 3beta-HSD genes occurred very late in mammals, with subsequent evolution in a similar manner in other lineages. Therefore, to a large extent, the 3beta-HSD gene family should have evolved to facilitate differential patterns of tissue- and cell-specific expression and regulation involving multiple signal transduction pathways, which are activated by several growth factors, steroids, and cytokines. Recent studies indicate that HSD3B2 gene regulation involves the orphan nuclear receptors steroidogenic factor-1 and dosage-sensitive sex reversal adrenal hypoplasia congenita critical region on the X chromosome gene 1 (DAX-1). Other findings suggest a potential regulatory role for STAT5 and STAT6 in transcriptional activation of HSD3B2 promoter. It was shown that epidermal growth factor (EGF) requires intact STAT5; on the other hand IL-4 induces HSD3B1 gene expression, along with IL-13, through STAT 6 activation. However, evidence suggests that multiple signal transduction pathways are involved in IL-4 mediated HSD3B1 gene expression. Indeed, a better understanding of the transcriptional factors responsible for the fine control of 3beta-HSD gene expression may provide insight into mechanisms involved in the functional cooperation between STATs and nuclear receptors as well as their potential interaction with other signaling transduction pathways such as GATA proteins. Finally, the elucidation of the molecular basis of 3beta-HSD deficiency has highlighted the fact that mutations in the HSD3B2 gene can result in a wide spectrum of molecular repercussions, which are associated with the different phenotypic manifestations of classical 3beta-HSD deficiency and also provide valuable information concerning the structure-function relationships of the 3beta-HSD superfamily. Furthermore, several recent studies using type I and type II purified enzymes have elegantly further characterized structure-function relationships responsible for kinetic differences and coenzyme specificity.

Identification of a human endonuclease complex reveals a link between tRNA splicing and pre-mRNA 3' end formation

tRNA splicing is a fundamental process required for cell growth and division. The first step in tRNA splicing is the removal of introns catalyzed in yeast by the tRNA splicing endonuclease. The enzyme responsible for intron removal in mammalian cells is unknown. We present the identification and characterization of the human tRNA splicing endonuclease. This enzyme consists of HsSen2, HsSen34, HsSen15, and HsSen54, homologs of the yeast tRNA endonuclease subunits. Additionally, we identified an alternatively spliced isoform of SEN2 that is part of a complex with unique RNA endonuclease activity. Surprisingly, both human endonuclease complexes are associated with pre-mRNA 3' end processing factors. Furthermore, siRNA-mediated depletion of SEN2 exhibited defects in maturation of both pre-tRNA and pre-mRNA. These findings demonstrate a link between pre-tRNA splicing and pre-mRNA 3' end formation, suggesting that the endonuclease subunits function in multiple RNA-processing events.

Facteurs de risque génétiques pour le cancer de la prostate

Prostate cancer is the most frequent malignant tumor among men over 50 years old. Its incidence varies according to countries and ethnic group. Known risk factors are race and positive family history of the disease. Familial aggregation (at least 2 cases in the family) is observed in about 20% of cases and an hereditary form of prostate cancer in 5%. This proportion increases with younger age at diagnosis. Six putative loci are already identified but undoubtedly, others will be found in forthcoming studies. The genetic heterogeneity observed in hereditary prostate cancer reflects variety of origins of the studied families. In some families, aggregation of prostate cancer and other cancers suggests the involvement of common predisposing genes. In other familial and in sporadic cases, the genetic component should be polygenic: prostate cancer wouldn't result to segregation of a major gene mutations transmitted according to a monogenic inheritance, but rather to sharing of alleles at many loci, each contributing to a small increase in cancer risk. Indeed, several genetic polymorphism were associated with an increased risk of developing prostate cancer and could explain the variations of prostate cancer incidence observed between populations.

Environmental, genetic, and molecular features of prostate cancer

Prostate cancer is the sixth most common cancer in the world and the third leading cause of cancer in men. The increase in the understanding of prostate carcinogenesis over the past 15 years has helped to define crucial steps in the natural history of the disease, namely initiation and progression to androgen independence. This heterogeneous disease encompasses a range of environmental and familial factors, which provides strong support for the use of chemopreventive strategies. Most patients with advanced prostate cancer are treated with androgen-deprivation therapy, which leads to a striking regression of androgen-responsive cancer cells. A transition from an androgen-responsive to an androgen-unresponsive stage is seen during the clinical course in almost all patients with prostate cancer. This transition also signals a substantial worsening of prognosis. Here, we review the most important findings in prostate carcinogenesis and the molecular anomalies associated with the androgen-refractory stage.

WITHDRAWN:Epidemiology of prostate cancer and its precursors

Ahead of Print article withdrawn by publisher.

The Caenorhabditis elegans homolog of the putative prostate cancer susceptibility gene ELAC2, hoe-1, plays a role in germline proliferation

The potential prostate cancer susceptibility gene ELAC2 has a Caenorhabditis elegans homolog (which we call hoe-1, for homolog of ELAC2). We have explored the biological role of this gene using RNAi to reduce gene activity. We found that worms subjected to hoe-1 RNAi are slow-growing and sterile. The sterility results from a drastic reduction in germline proliferation and cell-cycle arrest of germline nuclei. We found that hoe-1 is required for hyperproliferation phenotypes seen with mutations in three different genes, suggesting hoe-1 may be generally required for germline proliferation. We also found that reduction of hoe-1 by RNAi suppresses the multivulva (Muv) phenotype resulting from activating mutations in ras and that this suppression is likely to be indirect. This is the first demonstration of a biological role for this class of proteins in a complex eukaryote and adds important information when considering the role of ELAC2 in prostate cancer.

Molecular Epidemiology of Androgen-Metabolic Loci in Prostate Cancer: Predisposition and Progression

PURPOSE

We review recent molecular epidemiological data with regard to the association between several allelic variants of certain androgen-metabolic genes and the predisposition to and progression of prostate cancer.

MATERIALS AND METHODS

We review recent data dealing with genetic variations in androgens and the etiology of prostate cancer.

RESULTS

Recent molecular epidemiological data support an association between several allelic variants of certain androgen-metabolic genes and the predisposition to and progression of prostate cancer. While some of the allelic variants examined are consistently shown to be associated with increased prostate cancer risk, most of the variants show significant variability in risk.

CONCLUSIONS

A multidisciplinary attack on this problem, involving biochemistry, molecular genetics, pharmacogenetics, endocrinology and epidemiology, may be a useful paradigm in the analysis of prostate cancer and other complex human diseases. Based on the reviewed literature, we propose a guide on how and which single nucleotide polymorphisms to use in linkage and association studies of multifactorial phenotypes.

Relative risk of prostate cancer for men with affected relatives: systematic review and meta-analysis

An increased risk of prostate cancer associated with a family history of prostate cancer has been documented in multiple published reports. Risk has been shown to vary by degree of relationship and age of onset of disease in the affected relative. Several studies, using various designs, have estimated the relative risk (RR) for these associations. The purpose of our study was to identify and summarize published reports on the relationship between risk of prostate cancer and family history, which is defined as having a father, brother, any first- or second-degree relative or other relative affected with prostate cancer. A Medline and manual search from 1982 to 2000 identified 24 studies that reported RR and confidence intervals (CI) and satisfied inclusion criteria. Pooled RR estimates based upon a weighted average model were as follows: any affected family member RR = 1.93, CI 1.65-2.26; affected first-degree relative RR = 2.22, CI 2.06-2.40; affected second-degree relative RR = 1.88, CI 1.54-2.30; father with prostate cancer RR = 2.12, CI 1.82-2.51; and brother with prostate cancer RR = 2.87, CI 2.21-3.73). Statistical comparison of pooled data demonstrated that the RR is significantly higher for affected brother than for affected father (p < 0.03). A sensitivity analysis demonstrated that these results are robust with respect to population bias. This meta-analysis confirms that risk of prostate cancer is associated with family history of disease and improves the quantification of this risk.

Novel perspective: focusing on the X chromosome in reproductive cancers

In an XX female, one of the two X chromosomes has been inactivated during early embryonic life to achieve a compensation of X-linked gene products between males and females, leaving only one allele of X-linked genes functional. There are some X-linked genes escaping the X-inactivation, i.e., being expressed from both alleles. Escape from X-inactivation varies at different levels; some genes have both alleles active in some women but only one allele active in others, whereas some other genes have both alleles active in neoplastic tissue but only one allele active normally. The X-inactivation may be considered functionally equivalent to a loss of heterozygosity (LOH) for some genes, whereas escape from X-inactivation may be equivalent to functional gene amplification for others. The physiological LOH may make X-linked tumor suppressor genes lose their function more easily, compared with autosomal tumor suppressor genes, thus predisposing women to cancer formation more easily. Moreover, the human X chromosome contains many genes related to cancer or to sex and reproduction. All these properties of the X chromosome suggest that it may play more important roles than any autosomal chromosome in the development and progression of reproductive and urologic cancers.