Chromosomal abnormalities and related events in prostate cancer

Male-Specific Long Noncoding RNA TTTY15 Inhibits Non-Small Cell Lung Cancer Proliferation and Metastasis via TBX4

Gender affects cancer susceptibility. Currently, there are only a few studies on Y chromosome-linked long noncoding RNAs (lncRNAs), and the potential association between lncRNAs and cancers in males has not been fully elucidated. Here, we examined the expression of testis-specific transcript Y-linked 15 (TTTY15) in 37 males with non-small cell lung cancer (NSCLC), and performed circular chromosome conformation capture with next-generation sequencing to determine the genomic interaction regions of the TTTY15 gene. Our results showed that the expression levels of TTTY15 were lower in NSCLC tissues. Lower TTTY15 expression levels were associated with Tumor-Node-Metastasis (TNM) stage. A TTTY15 knockdown promoted malignant transformation of NSCLC cells. Based on the bioinformatics analysis of circular chromosome conformation capture data, we found that T-box transcription factor 4 (TBX4) may be a potential target gene of TTTY15. The RNA immunoprecipitation and chromatin immunoprecipitation results showed that TTTY15 may interact with DNA (cytosine-5)-methyltransferase 3A (DNMT3A), and the TTTY15 knockdown increased the binding of DNMT3A to the TBX4 promoter. We concluded that low TTTY15 expression correlates with worse prognosis among patients with NSCLC. TTTY15 promotes TBX4 expression via DNMT3A-mediated regulation. The identification of lncRNAs encoded by male-specific genes may help to identify potential targets for NSCLC therapy.

The Genomics of Prostate Cancer: A Historic Perspective

The genomics of prostate cancer (PCA) has been difficult to study compared with some other cancer types for a multitude of reasons, despite significant efforts since the early 1980s. Overcoming some of these obstacles has paved the way for greater insight into the genomics of PCA. The advent of high-throughput technologies coming from the initial use of microsatellite and oligonucleotide probes gave rise to techniques like comparative genomic hybridization (CGH). With the introduction of massively parallel genomic sequencing, referred to as next-generation sequencing (NGS), a deeper understanding of cancer genomics in general has occurred. Along with these technologic advances, there has been the development of computational biology and statistical approaches to address novel large data sets characterized by single base resolution. This review will provide a historic perspective of PCA genomics with an emphasis on the cardinal mutations and alterations observed to be consistently seen in PCA for both hormone-naïve localized PCA and castration-resistant prostate cancer (CRPC). There will be a focus on alterations that have the greatest potential to play a role in disease progression and therapy management.

Y Chromosome Missing Protein, TBL1Y, May Play an Important Role in Cardiac Differentiation

Despite evidence for sex-specific cardiovascular physiology and pathophysiology, the biological basis for this dimorphism remains to be explored. Apart from hormonal factors, gender-related characteristics may reside in the function of sex chromosomes during cardiac development. In this study, we investigated the differential expression of the male-specific region of the Y chromosome (MSY) genes and their X counterparts during cardiac differentiation of human embryonic stem cells (hESC). We observed alterations in mRNA and protein levels of TBL1Y, PCDH11Y, ZFY, KDM5D, USP9Y, RPS4Y1, DDX3Y, PRY, XKRY, BCORP1, RBMY, HSFY, and UTY, which accompanied changes in intracellular localization. Of them, the abundance of a Y chromosome missing protein, TBL1Y, showed a significant increase during differentiation while the expression level of its X counterpart decreased. Consistently, reducing TBL1Y cellular level using siRNA approach influenced cardiac differentiation by reducing its efficacy as well as increasing the probability of impaired contractions. TBL1Y knockdown may have negatively impacted cardiogenesis by CtBP stabilization. Furthermore, we presented compelling experimental evidence to distinguish TBL1Y from TBL1X, its highly similar X chromosome homologue, and proposed reclassification of TBL1Y as "found missing protein" (PE1). Our results demonstrated that MSY proteins may play an important role in cardiac development.

Human Chromosome Y and Haplogroups; introducing YDHS Database

BACKGROUND

As the high throughput sequencing efforts generate more biological information, scientists from different disciplines are interpreting the polymorphisms that make us unique. In addition, there is an increasing trend in general public to research their own genealogy, find distant relatives and to know more about their biological background. Commercial vendors are providing analyses of mitochondrial and Y-chromosomal markers for such purposes. Clearly, an easy-to-use free interface to the existing data on the identified variants would be in the interest of general public and professionals less familiar with the field. Here we introduce a novel metadatabase YDHS that aims to provide such an interface for Y-chromosomal DNA (Y-DNA) haplogroups and sequence variants.

METHODS

The database uses ISOGG Y-DNA tree as the source of mutations and haplogroups and by using genomic positions of the mutations the database links them to genes and other biological entities. YDHS contains analysis tools for deeper Y-SNP analysis.

RESULTS

YDHS addresses the shortage of Y-DNA related databases. We have tested our database using a set of different cases from literature ranging from infertility to autism. The database is at http://www.semanticgen.net/ydhs

CONCLUSIONS

Y-chromosomal DNA (Y-DNA) haplogroups and sequence variants have not been in the scientific limelight, excluding certain specialized fields like forensics, mainly because there is not much freely available information or it is scattered in different sources. However, as we have demonstrated Y-SNPs do play a role in various cases on the haplogroup level and it is possible to create a free Y-DNA dedicated bioinformatics resource.

A fresh look at the male-specific region of the human Y chromosome

The Chromosome-centric Human Proteome Project (C-HPP) aims to systematically map the entire human proteome with the intent to enhance our understanding of human biology at the cellular level. This project attempts simultaneously to establish a sound basis for the development of diagnostic, prognostic, therapeutic, and preventive medical applications. In Iran, current efforts focus on mapping the proteome of the human Y chromosome. The male-specific region of the Y chromosome (MSY) is unique in many aspects and comprises 95% of the chromosome's length. The MSY continually retains its haploid state and is full of repeated sequences. It is responsible for important biological roles such as sex determination and male fertility. Here, we present the most recent update of MSY protein-encoding genes and their association with various traits and diseases including sex determination and reversal, spermatogenesis and male infertility, cancers such as prostate cancers, sex-specific effects on the brain and behavior, and graft-versus-host disease. We also present information available from RNA sequencing, protein-protein interaction, post-translational modification of MSY protein-coding genes and their implications in biological systems. An overview of Human Y chromosome Proteome Project is presented and a systematic approach is suggested to ensure that at least one of each predicted protein-coding gene's major representative proteins will be characterized in the context of its major anatomical sites of expression, its abundance, and its functional relevance in a biological and/or medical context. There are many technical and biological issues that will need to be overcome in order to accomplish the full scale mapping.

Adenoviral-mediated pHyde gene transfer and cisplatin additively inhibit human prostate cancer growth by enhancing apoptosis

BACKGROUND

A novel gene, rat pHyde, has been cloned by us recently. The rat pHyde was shown by the same group to have growth inhibitory effects on human prostate cancer through the induction of apoptosis.

METHODS

In this report, a human homologue, hpHyde of the rat pHyde, was cloned by cDNA libraries screening. The database search and in situ hybridization were used to map the genomic loci of hpHyde in human chromosome. The anti-prostate cancer effects of pHyde in conjunction with chemotherapy agent were analyzed by in vitro and in vivo assays using adenoviral vector expressing pHyde (AdRSVpHyde) in combination with DNA damaging chemotherapeutic agent, cisplatin, and docetaxel, respectively.

RESULTS

Database search and FISH analysis consistently indicated that hpHyde gene localizes at human chromosome 2q14. Protein sequence analysis suggests that hpHyde may be a plasma membrane protein. hpHyde is differentially expressed in various normal human tissues and organs, suggesting that hpHyde may play roles in development and differentiation. Growth suppression and induction of apoptosis were additively greater in DU145 human prostate cancer cells treated with AdRSVpHyde and cisplatin than either agent alone both in vitro and in vivo. Moreover, AdRSVpHyde and docetaxel also have a similar additively inhibitory effect on DU145 cell growth.

CONCLUSIONS

A novel gene hpHyde, the human homologue of rat pHyde, has been cloned and its genomic location in the human chromosome has been identified. Our results support the potential use of pHyde for prostate cancer gene therapy coupled with chemotherapy to improve therapeutic index.

The impact of genomic alterations on the transcriptome: a prostate cancer cell line case study

Genetic instability may lead to the loss/gain of transcriptional control. Here we investigated the effect of genomic instability, that is loss/gain of chromosomal regions on the global transcriptome of prostate cancer cell line DU145. The genomic loss/gain map obtained through BAC array-based CGH was superimposed on the dynamic transcriptome of DU145 cells treated with serum for 0 h (serum starved), 2 h and 12 h. The genomic analysis suggested that in DU145 cells: (1) chromosomal gains are prominent than losses and (2) copy number changes are associated with chromosome-specific and dynamic gene expression regulatory mechanisms. A significant proportion of the genes in the stable regions of the chromosome were up-regulated whereas a higher proportion of genes were down-regulated at 2 and 12 h in the deleted regions of the chromosomes following serum treatment. No change in expression was observed for the genes in the gained regions over a period of time. This analysis led us to propose that loss of heterozygosity leads to an overall transcriptional down-regulation that may further lead to a decrease in the expression of putative tumor suppressors. The genomic profile of DU145 is similar to pathological specimens of prostate cancer, hence the genomic/transcriptomic signature of DU145 can be used to understand the pathology of prostate cancer. It is expected that this analysis will allow a better understanding of transcriptional regulatory mechanisms in the context of genomic loss and gain and may lead to the discovery of novel oncogenes and tumor suppressors and the underlying regulatory pathways.

Differences in gene expression in prostate cancer, normal appearing prostate tissue adjacent to cancer and prostate tissue from cancer free organ donors

Background

Typical high throughput microarrays experiments compare gene expression across two specimen classes – an experimental class and baseline (or comparison) class. The choice of specimen classes is a major factor in the differential gene expression patterns revealed by these experiments. In most studies of prostate cancer, histologically malignant tissue is chosen as the experimental class while normal appearing prostate tissue adjacent to the tumor (adjacent normal) is chosen as the baseline against which comparison is made. However, normal appearing prostate tissue from tumor free organ donors represents an alterative source of baseline tissue for differential expression studies.

Methods

To examine the effect of using donor normal tissue as opposed to adjacent normal tissue as a baseline for prostate cancer expression studies, we compared, using oligonucleotide microarrays, the expression profiles of primary prostate cancer (tumor), adjacent normal tissue and normal tissue from tumor free donors.

Results

Statistical analysis using Significance Analysis of Microarrays (SAM) demonstrates the presence of unique gene expression profiles for each of these specimen classes. The tumor v donor expression profile was more extensive that the tumor v adjacent normal profile. The differentially expressed gene lists from tumor v donor, tumor v adjacent normal and adjacent normal v donor comparisons were examined to identify regulated genes. When donors were used as the baseline, similar genes are highly regulated in both tumor and adjacent normal tissue. Significantly, both tumor and adjacent normal tissue exhibit significant up regulation of proliferation related genes including transcription factors, signal transducers and growth regulators compared to donor tissue. These genes were not picked up in a direct comparison of tumor and adjacent normal tissues.

Conclusions

The up-regulation of these gene types in both tissue types is an unexpected finding and suggests that normal appearing prostate tissue can undergo genetic changes in response to or in expectation of morphologic cancer. A possible field effect surrounding prostate cancers and the implications of these findings for characterizing gene expression changes in prostate tumors are discussed.

Detection of Chromosomal Aberrations in Prostate Cancer by Fluorescence In Situ Hybridization (FISH)

PURPOSE

Fluorescence in situ hybridization (FISH) is a powerful tool for quantitative analysis of chromosomes and genes and can be applied in a variety of specimens, including cell cultures, isolated nuclei from fresh and fixed tissues, and histological tissue sections. For detection of numerical chromosome aberrations, we examined prostatic cancer samples at our department. In addition, we also observed primary and secondary aberrations taking part in the initiation and progression of tumours.

MATERIALS AND METHODS

FISH using chromosome-specific alpha-satellite DNA probes for chromosomes 7, 8, 9, 10, 17, X and Y was performed on 19 prostatic cancer and 19 benign prostatic hyperplasia (BPH) samples obtained from transurethral resection (TUR) and archival paraffin-embedded blocks.

RESULTS

Numerical aberrations were observed in 41% of the tumours studied. A range of aberrant copy numbers of chromosome 9 (68%), 7 (63%), 8 (58%), 17 (37%), Y (32%) and 10 (26%) was observed. We did not observe significant aberrations in BPH samples. In prostate cancer patients, chromosomes 7 (47%), 8 (58%) and 9 (63%) were monosomic by FISH. Monosomy 8 and 9 were significant differences (p>0.05) between prostate cancer and BPH patients.

CONCLUSIONS

FISH analysis could be observed an one of strongest methods of analysis in detecting numerical aberrations of individual chromosomes with application to paraffin-block samples, metaphase and, interphase nuclei. To our knowledge, this analysis is firstly studied in Turkish patients. Therefore, results of this analysis may be important for Turkish patients.

Molecular and genetic prognostic factors of prostate cancer

Prostate cancer is the most commonly diagnosed cancer in Western males, responsible for 3% of all deaths in men over 55 years of age and second only to lung cancer as a cause of cancer death. Biomarkers have become an important diagnostic tool in prostate cancer. The discovery of the serum marker prostate-specific antigen (PSA) significantly facilitated the detection and management of prostate cancer. As we enter into the post-genomics era, novel biomarkers of prostate cancer of therapeutic significance will invariably emerge. Here we review a series of existing and emerging molecular-based prognostic markers particularly with radiotherapy.

Molecular cytogenetic aberrations in CD30+ anaplastic large cell lymphoma cell lines

Anaplastic large cell lymphomas (ALCL) in children represent a heterogeneous group of neoplasms with regard to the cell lineages involved. The chromosomal 5q35 breakpoint (bp) and the expression of the NPM/ALK fusion gene are the most remarkable molecular cytogenetic features of these malignancies. To identify new locations of ALCL-related oncogenes, comparative genomic hybridization (CGH) was applied to three ALCL cell lines (SU-DHL-1, Karpas 299, and DEL) exhibiting the 5q35 bp and expressing the NPM/ALK transcript. The CGH profiles were compared with those obtained with DNA from U937, HL-60 cells, and altered lymph nodes from two children with ALCL. Significant DNA copy number gains and/or losses were observed on several chromosomes in all ALCL cell lines. Distinct amplicons were detected on 1q21 approximately q44 (DEL), 7q12 (SU-DHL-1), and 1q12 approximately q22 (Karpas 299) regions. The NPM/ALK fusion gene was confirmed by fluorescence in situ hybridization (FISH) analysis in more than 80% of interphase nuclei and metaphase spreads. Enhanced expression of TGF-beta2 and c-MET candidate genes located at the amplified regions was revealed in DEL and SU-DHL1 cell lines by Northern blot analysis. These findings delineate chromosomal imbalances in ALCL-derived cell lines in parallel with high level of amplification covering target DNA sequences, which could play a role in ALCL pathogenesis.

Prognostic markers in prostate cancer

In this review, a series of relatively well-documented ancillary biomarkers and emerging molecular assays are evaluated for their relative ability to predict prognosis in prostate cancer. Prognostic factors that have achieved widespread use and classified as Category I by the College of American Pathologists Solid Tumor Prognostic Factor Consensus Conference are compared with newer tests that are beginning to be used in clinical practice (Category II) and emerging molecular-based assays that have yet to be widely validated in the published literature or clinical trials (Category III).

Morphologic and molecular prognostic markers in prostate cancer

In this review, a series of traditional morphology-based measurements, relatively well-documented ancillary biomarkers, and emerging molecular assays are evaluated for their relative ability to predict prognosis in prostate cancer. Prognostic factors that have achieved widespread use and are classified as category I by the College of American Pathologists' Solid Tumor Prognostic Factor Consensus Conference are compared with newer tests that are beginning to be used in clinical practice (category II) and emerging molecular-based assays that have yet to be widely validated in the published literature or in clinical trials (category III).

Apoptosis induction in prostate cancer cells by a novel gene product, pHyde, involves caspase-3

A novel gene, pHyde, was recently cloned from Dunning rat prostate cancer cells. A recombinant adenovirus containing pHyde cDNA gene (AdpHyde) was generated to investigate the biological function of pHyde protein. AdpHyde inhibited the growth of human prostate cancer cells. Apoptosis was induced in AdpHyde transduced cells as demonstrated by DAPI (4', 6-diamino-2-phenylindole), TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP nick and labeling) staining, and flow cytometry assays. Apoptosis was also induced in human xenograft prostate cancer tumors growing in nude mice following treatment with AdpHyde. AdpHyde transduction resulted in a dose-dependent stimulation of caspase-3 activity in DU145 cells which was blocked by DEVD (succinyl-Asp-Glu-Val-Asp-aldehyde) and VAD (benzyloxycarbonyl - Val - Ala - Asp -fluoromethylketone), inhibitors specifically against caspase-3. Moreover, cancer cells that lacked expression of endogenous caspase-3 were not or barely inhibited by pHyde. These results taken together suggest that pHyde inhibits cancer growth by inducing apoptosis through a caspase-3 dependent pathway.

Clinical and experimental progression of a new model of human prostate cancer and therapeutic approach

We report the clinical evolution of a prostate cancer, metastasizing to lungs and bones, recurring locally, and escaping from anti-androgen therapy. Key event of biological progression of the patient's tumor was the coincidence of allelic imbalance accumulation and of bone metastases occurrence. The recurrent tumor was established as the transplantable xenograft PAC120 in nude mice, where it grew locally. PAC120 displayed the same immunophenotype of the original tumor (positive for keratin, vimentin, prostatic acid phosphatase, and Leu-7) and expressed human HOXB9, HOXA4, HER-2/neu, and prostate-specific antigen genes, as detected by reverse transcriptase-polymerase chain reaction. It formed lung micrometastases detected by mRNA expression of human genes. Cytogenetic analysis demonstrated numerous alterations reflecting the tumor evolution. PAC120 was still hormone-dependent; its growth was strongly inhibited by the new gonadotropin-releasing hormone antagonist FE 200486 but weakly by gonadotropin-releasing hormone superagonist D-Trp(6)-luteinizing-hormone releasing hormone (decapeptyl). Tumor growth inhibition induced by anti-hormone therapy was linked to the hormone deprivation degree, more important and more stable with FE 200486 than with D-Trp(6)-luteinizing-hormone releasing hormone. Surgical castration of mice led to tumor regressions but did not prevent late recurrences. Transition to hormone-independent tumors was frequently associated with a mucoid differentiation or with a neuroendocrine-like pattern. Independent variations of mRNA expression of HER-2/neu and prostate-specific antigen were observed in hormone-independent tumors whereas HOXB9 gene expression was constant. In conclusion, PAC120 xenograft, a new model of hormone-dependent prostate cancer retained the progression potential of the original tumor, opening the opportunity to study the hormone dependence escape mechanism.

Identification of a novel gene on chromosome 13 between BRCA-2 and RB-1

METHODS AND RESULTS

By differential display we isolated a new cDNA-fragment, named C13, that is downregulated in malignant prostate tissues. Northern hybridization revealed the fragment to be part of 3.0 and 4.4 kb mRNAs. Fluorescence in situ hybridization, Southern blotting and radiation hybrid mapping demonstrated a chromosomal localization of C13 on 13q12-14 closest to the SHGC-34125 marker. In the 5% chromosomal environment of C13 we detected changes of the allelic status in 13 of 21 prostate cancers. A downregulation was detected at the mRNA level in patients with advanced carcinoma. The 3.0 kb full length cDNA clone encodes a protein with an open reading frame of 2,202 bp or 733 amino acids. The corresponding protein contains a putative nuclear localization signal, several glutamine clusters and an alpha-helix-rich domain. By in situ RNA hybridization we could demonstrate the mainly epithelial expression of the C13 mRNA in prostatic tissue.

CONCLUSIONS

The localization of C13 between the tumor suppressor genes BRCA-2 and RB-1, the detected allelic imbalances, the downregulation of its mRNA in some prostatic cancer tissues, the epithelial expression and the described protein structure suggest that this gene encodes a protein that may have tumor or metastasis suppressing function in prostate tissue.

Molecular genetics of prostate cancer

The molecular mechanisms underlying the development and progression of prostate cancer are poorly understood. Epidemiological studies have suggested that 5-10% of all prostate cancers are familial, and numerous chromosomal loci have been associated with prostate cancer in multicentre linkage studies. However, no putative susceptibility genes harboured in these chromosomal regions have thus far been identified. Several recurrent chromosomal alterations in prostate cancer have been detected in comparative genomic hybridization (CGH) and loss of heterozygosity (LOH) analysis. The target genes for many of these aberrations are still not known. It seems that the androgen receptor (AR) signalling pathway plays a crucial role in both early development as well as in late progression of the disease. Both germ-line and somatic genetic alterations in the AR gene have been demonstrated in prostate cancer patients. The intention of this review is to summarize the current knowledge of molecular mechanisms in the development of prostate cancer.

Hypermethylation of the caveolin-1 gene promoter in prostate cancer

BACKGROUND

Hypermethylation of CpG islands in the promoter regions of tumor suppressor genes is one mechanism of tumorigenesis. Caveolin-1 (Cav-1), a gene coding for the structural component of cellular caveolae, is involved in cell signaling and has been proposed to be a tumor suppressor gene in several malignancies. This gene maps to 7q31.1, a site known to be deleted in some prostate tumors. We chose to examine the methylation status of the promoter region of Cav-1 to determine whether this gene could function as a tumor suppressor in prostate cancer

METHODS

Genomic DNA from both tumor and normal prostate epithelial cells was obtained from paraffin-embedded prostate sections by laser capture microdissection (LCM). The methylation status of 24 CpG sites at the 5' promoter region of Cav-1 was analyzed by bisulfite-direct-sequencing after amplification by PCR using primers specific for bisulfate modified DNA. Immunohistochemistry staining with a cav-1-specific antibody was also performed to evaluate the expression of the gene

RESULTS

Twenty of the 22 (90.9%) informative cases showed promoter hypermethylation in the tumor cell population when compared with adjacent normal prostate cells with an average Methylation Index (potential frequency of total possible methylated Cs) from tumor cells equal to 0.426 vs. 0.186 for normal cells (P = 0.001). While no association with Gleason grade was found, overall increased methylation correlated with PSA failure (P = 0.016), suggestive of clinical recurrence. Elevated immunoreactivity with a Cav-1 antibody was observed in tumor cells from 7 of 26 prostate samples tested; this was associated with a Gleason score but not correlated with PSA failure or Methylation Index

CONCLUSIONS

CpG sites at the 5' promoter of Cav-1 are more methylated in tumor than in adjacent normal prostate cells. Hypermethylation of the Cav-1 promoter supports the notion that Cav-1 may function as a tumor suppressor gene in prostate cancer and evidence is presented suggesting that methylation status of this gene is not only a marker for cancer but also may be predictive of outcome.

Loss of the short arm of the Y chromosome in human prostate carcinoma

A change in Y chromosome number is one of the many cytogenetic abnormalities reported in human prostate tumors. However, reports in the literature have varied regarding the frequency of Y loss or gain and the significance of Y aneusomy with respect to the biology of the disease. We have conducted an analysis of the Y chromosome in malignant and benign hyperplastic human prostate epithelium in order to determine whether regional Y loss occurs in prostate cancer. To accomplish this we performed dual-color fluorescence in situ hybridization (FISH) on serial sections of paraffin-embedded prostate tumor tissues using either a Yp (SRY), Ycen (alpha-satellite) or Yq (satellite 3) probe, and an Xcen (alpha-satellite) probe that served as a control for hybridization and nuclear truncation. The results of our FISH analysis demonstrated loss of Yp in the malignant epithelium of 14/40 (35%) prostate tumor sections examined. We also found loss of Yq in 4/40 (10%) of the samples, with one of these exhibiting accompanying Yp loss. The remaining samples, 23/40 (58%), retained both Yp and Yq markers, with no evidence of either Ycen loss or Y gain in any of the tumor samples examined. In addition, Y loss was detected in the benign hyperplastic regions in nearly one-half of the tissue sections that exhibited Y loss in the malignant epithelium. These results demonstrate that regional chromosome Y loss occurs in prostate cancer, that loss of Yp is the most frequent event, and suggest that this loss may in some cases be a precursor to prostate malignancy.

Molecular cytogenetics of prostate cancer

Prostate cancer is the most common malignancy among men in Western industrialized countries. The molecular pathogenesis of the disease is poorly known. Over the past 10 years, chromosomal aberrations in prostate cancer have been studied with several techniques, such as loss of heterozygosity (LOH), classical cytogenetics, and molecular cytogenetics, namely with fluorescence in situ hybridization (FISH) and comparative genomic hybridization (CGH). These analyses, especially those performed by CGH, have enabled the distinction of the predominant chromosomal regions of involvement in prostate cancer. Studies have shown that the most common chromosomal alterations in prostate cancer are losses at 1p, 6q, 8p, 10q, 13q, 16q, and 18q and gains at 1q, 2p, 7, 8q, 18q, and Xq. Fluorescence in situ hybridization (FISH) has been used to identify the target genes for some of these chromosomal alterations. For example, amplifications of AR (at Xq12), MYC (8q24), and EIF3S3 (8q23) have been found in a large fraction of hormone-refractory prostate cancer by FISH. However, many of the critical oncogenes and tumor suppressor genes located in the altered chromosomal regions have not yet been identified.

Deletion (1)(q12) and double minutes in a metastatic adenocarcinoma of the prostate

Cytogenetic analysis after short-term cultures were performed on an invasive and moderately-differentiated prostatic adenocarcinoma. The results showed a normal male chromosomal complement in most metaphases examined. Furthermore, several abnormalities were found, including del(1)(q12), double minute and ring chromosomes, acentric fragments, triradial figures, and near-tetraploid cells.

Chromosomal basis of adenocarcinoma of the prostate

Prostate cancer is the most frequent malignancy and the second leading cause of cancer deaths among males in the Western world. The clinical course of the disease is highly complex, and genetic factors underlying tumorigenesis are poorly understood. The challenge that lies ahead is to identify the important gene(s) that causes adenocarcinoma of the prostate. Chromosomal findings by cytogenetic and molecular methods, including Southern blotting, microsatellite analysis, fluorescence in situ hybridization, and comparative genomic hybridization, revealed a high frequency of chromosomal aberrations of heterogeneous nature, including: -1, +1, -1q, +4, -6q, -7, +7, -8, -8p, -8q, +i(8q), -9, -9p, -10, +10, +11, -12, -13q, -16, -16q, +16, -17, +17, +17q, -18, +18, -18q, +19p, +20q, +X, -Xq, -Y, and +Y. Specific chromosomal regions of alterations were 1q24-25, 2cen-q31, 5cen-q23.3, 6q14-23.2, 7q22-q31, 8p12-21, 8p22, 8q24-qter, 10q22.1, 10q23-25, 11p11.2, 16q24, 17p13.1, 18q12.2, and Xq11-12. Recently, a predisposing gene for early onset has been localized on 1q42.2-43. The losses of heterozygosity at specific chromosomal loci from chromosomes 5q, 6q, 7q, 8p, 8q, 10q, 13q, 16q, 17p, 17q, and 18q are generally correlated with poor prognosis in advanced tumor stage. In addition, an abnormal function of known tumor suppressor genes from these regions have been observed in prostate cancer. Although, the amplification of the androgen receptor gene at Xq11-13 and HER-2/neu gene at 17q11.2-q12 are novel findings, no single gene has been implicated in harboring prostate cancer. Frequent inactivation of PTEN/MMAC1 tumor suppressor gene at 10q23, MXI-1 at 10q25, KAI-1 at 11p11.2, Rb at 13q14.2, and p53 at 17p13.1 and deregulation of c-myc oncogene at 8q24 have recently been the subject of intense scrutiny and debate.

Microsatellite instability and loss of heterozygosity in prostatic carcinomas: comparison of primary tumors, and of corresponding recurrences after androgen-deprivation therapy and lymph-node metastases

BACKGROUND

The molecular mechanisms leading to prostate cancer progression are poorly understood. In particular, those changes which are responsible for androgen-independent growth and metastatic spread in prostate cancer are an issue of current investigations.

METHODS

To gain more insight into these processes, paired microdissected samples from both untreated, locally advanced primary tumors (n = 20) and recurrences (n = 20) after conventional androgen-deprivation therapy (ADT) were analyzed retrospectively for microsatellite instability (MSI) and loss of heterozygosity (LOH) at nine loci on chromosomes 8, 18, and X by polymerase chain reaction. In parallel, 12 prostatic carcinomas treated by radical prostatectomy and nine corresponding lymph-node metastases were analyzed in the same way.

RESULTS

The group treated with ADT showed a total of 10 MSI in 7 of the primary tumors (35%): 4 of these (20%) at one locus, and 3 of these (15%) at two loci. In the recurrences, MSI was observed in 4 cases (20%): 3 of these at one locus (15%), and 1 of these (5%) at two loci. LOH was found in 8 cases (40%) before as well as after ADT. In the radically resected carcinomas, MSI could be detected at two chromosomal loci in one of the primary tumors (8%) and in one of the metastases (11%); LOH was found in 2 primaries (16%) and 3 metastases (33%).

CONCLUSIONS

Although MSI can be found in advanced prostatic carcinomas, it apparently does not play a major role in the progression of prostate cancer regarding androgen-independent growth or lymphogenous spread.

Abnormal restriction pattern of PIP gene associated with human primary prostate cancers

The PIP gene, localized in the 7q34 region that contains a number of fragile sites such as FRA 7H and FRA TI, codes for gp17/PIP, a protein secreted by breast apocrine tumors. We analyzed the integrity of this gene in 20 tumors of the urogenital tract. We found rearranged EcoRI fragments in 5 of 15 primary prostate carcinomas. No rearrangement was found in normal prostates derived from five patients undergoing prostatocystectomy during treatment of bladder cancers. By Southern blot hybridization with PIP gene exon-specific probes, the rearrangements were mapped at or near the 3' end of the gene. These abnormalities were found, not only in the neoplastic cells invading the prostatic tissues, but also in seminal vesicles without histologic tumoral features. These data suggest a critical role of the PIP gene or neighboring genes in prostate cancer.

Y chromosome enumeration in touch preparations from 42 prostate tumors by interphase fluorescence in situ hybridization analysis

A change in Y chromosome number is but one of the many cytogenetic abnormalities reported in human prostate tumors. However, reports in the literature have varied regarding the frequency of Y loss or gain, whether it is restricted to the cancerous tissue, and its relation to the biology of the disease. The most frequently used materials for analysis of Y enumeration have been metaphase spreads from short-term cell cultures of prostate tumor tissue and paraffin-embedded tissue sections. Analysis of Y chromosome number by using metaphase spreads on short-term cultures can be misleading owing to clonal cell selection during the establishment of these cultures. This may result in an incomplete representation of the loss/gain pattern in the tumor as a whole. Studies using paraffin-embedded tissue sections can be complicated by apparent chromosome loss due to nuclear truncation as a result of tumor sectioning. In an attempt to circumvent these problems, we have used touch preparations from human prostate tumors to search for Y chromosome loss. Fluorescence in situ hybridization analysis was conducted by using a whole chromosome Y paint, with an alpha-satellite chromosome 3 probe as a control, on tumor samples from 42 patients ages 40-75. The results demonstrated a gain of Y in a single prostate tumor sample, with no convincing evidence for loss of the entire Y chromosome in any of the other 41 samples examined. The results suggest that loss of the entire Y chromosome is an infrequent event in prostate cancer.

Pathological and karyotypic abnormalities in advanced gastric carcinomas

Twenty samples of stomach cancers were analyzed by conventional cytogenetic and histopathological techniques. Nineteen tumors were diagnosed as adenocarcinomas and one as an adenosquamous carcinoma. Multiple and complex chromosomal abnormalities were found in the cases evaluated cytogenetically. This heterogeneity of chromosomal changes appears to indicate a certain correlation with tumor progression. Histological analysis showed a distinctive growth pattern of gastric cancer samples and a potential for invasiveness and recurrence for all tumors as well as a poor prognosis.

Numerical chromosomal anomalies in latent adenocarcinomas of the prostate

BACKGROUND

Even the high incidence of clinically diagnosed prostate cancer is exceeded by the frequency of tumors detected at autopsy. However, there is some debate concerning the malignant potential of these so-called "latent prostate cancers." In this study, prostate cancers detected at autopsy were investigated for the presence of numerical aberrations of chromosomes 7, 10, 17, X, and Y.

METHODS

Prostates from 57 autopsies, performed on male patients aged 45 years or older, were histologically investigated for the presence of cancer. Interphase cytogenetics, an in situ hybridization method with chromosome-specific probes, was performed on paraffin sections.

RESULTS

Of the 57 specimens investigated, 23 contained foci of prostate cancer. Three prostates contained more than one tumor focus. Interphase cytogenetics could be performed successfully in 19 specimens. Of the 22 tumor foci investigated, 14 were disomic and 8 were nondisomic for the five chromosomes tested. Ploidy correlated significantly with the presence of a Gleason score of 7 or higher (P = 0.0109), but not with a tumor volume larger than 0.5 cm3, or with patient age over 75 years.

CONCLUSIONS

Some latent prostate cancers display a nondisomic chromosomal status and a low histologic differentiation in spite of a small tumor volume, suggesting a more aggressive potential in a subset of these tumors.

Chromosome 7 abnormalities in prostate cancer detected by dual-color fluorescence in situ hybridization

Aneusomy of chromosome 7 and loss at 7q (especially 7q31.1) have been reported in prostate cancer. To further investigate abnormalities of 7q and the relationship with whole chromosome 7 changes, we have conducted a dual-color fluorescence in situ hybridization (FISH) analysis on isolated nuclei from 28 primary prostate cancers. A pericentromeric probe for chromosome 7, five newly isolated sequence-specific bacterial artificial chromosome (BAC) probes from 7q31.1, and one BAC for the epidermal growth factor receptor (EGFR) gene at 7p12 were used in dual color hybridizations. Pericentromeric probes for chromosomes X and 4 were also used as controls. Sixteen (57.1%) of the 28 tumors showed clonal aberrations. Nine of them were trisomy 7 and four were hypertetrasomy for chromosome 7. Deletions at 7q31.1 were found in two of the high grade tumors. With the exception of these two cases, all other cases showed concordant results using all probes. These findings confirm previous studies that aneusomy of 7 is associated with prostate cancer progression, and there may be a tumor suppressor gene (TSG) at 7q31.1 which is associated with tumor progression. In addition, our study indicates: (1) the deletion pattern of individual nuclei infers that deletions at 7q31.1 precede reduplications of chromosome 7; and (2) the amplification of EGFR was not detected at the DNA level, suggesting that activation of this oncogene may play a minor role in prostate cancer.

Chromosome 16q24 deletion and decreased E-cadherin expression: possible association with metastatic potential in prostate cancer

BACKGROUND

Deletion of chromosome 16q is a frequent aberration in prostatic carcinoma, indicating the existence of candidate tumor suppressor genes involved in the pathogenesis of prostate cancer.

METHODS

Chromosome 16 numerical aberration and loss of 16q were studied by fluorescence in situ hybridization in 31 primary and 22 metastatic tumors from 53 patients. The results were compared with E-cadherin expression, tumor grade and stage, and DNA ploidy.

RESULTS

Numerical chromosome 16 aberrations, 16q deletion, and loss of E-cadherin expression were found in 29%, 35%, and 29% of the primary tumors, respectively, and in 73%, 73%, and 73% of the metastases, respectively. High tumor grade and DNA aneuploidy were also found to have significant correlation with metastases.

CONCLUSIONS

Deletion of chromosome 16q24 and/or loss of the E-cadherin function appears in a high frequency in metastases of prostate cancer. The strong correlations suggest that they may be important risk factors, contributing to the metastatic potential of the tumor.

Cytogenetic analysis of 39 prostate carcinomas and evaluation of short-term tissue culture techniques

Karyotypic analysis was performed on 102 prostate cancer specimens which were obtained through radical prostatectomy, transurethral resection, or regional lymph node dissection. Short term tissue culture was applied in all cases. Of the media and growth factors evaluated, F12/DMEM, supplemented with 2% fetal calf serum, insulin, epidermal growth factor, hydrocortisone, and cholera toxin produced the largest increase of in vitro proliferation. Such in vitro cultured cells were all phenotypically acinar epithelial cells, the supposed targets for neoplastic transformation. Stromal cell growth appeared to be completely suppressed. Of the three culture techniques investigated, the method developed in Lund, Sweden, was the most successful: 11/15 cultures yielded metaphases and, in three of these, clonal aberrations were identified. All 39 karyotypes obtained essentially had a 46,XY karyotype with clonal aberrations (eight cases) and/or nonclonal aberrations (30 cases). Clonal structural aberrations involved 2p, 3q, 11p, 17p, and 21q. The clonal numerical aberrations found were: + 8, + dmin, and -Y. The most frequently observed nonclonal aberrations were 8p deletions (five cases) and loss of 6, 7, 8, 15, 17, 18, 21, and/or Y (> or = five cases). In summary, clonal aberrations were observed in 20% of the evaluable PC cell cultures, and nonclonal aberrations in 77%. So, although diploid cells without clonal abnormalities still had a growth advantage, under optimal conditions PC cells were able to proliferate in primary in vitro culture.

Genetic alterations in prostate cancer cell lines detected by comparative genomic hybridization

Recent studies have identified several chromosomal regions that are altered in prostate cancer. However, the specific genes affected are, in most of the cases, not known. Cancer cell lines could provide a valuable resource for cloning of genes that are commonly affected in cancer. The first step in the identification of such genes is the detection of chromosomal aberrations. Here, we have used comparative genomic hybridization (CGH) to screen for genetic alterations in four prostate cancer cell lines, LNCaP, DU145, PC-3, and TSU-Pr1. The analysis showed that, except for the LNCaP, these cell lines contained many genetic changes (> or = 10 per cell line), suggesting that they resemble genetically more closely hormone-refractory or metastatic than primary prostate carcinomas. All the chromosomal regions that have been implicated in prostate cancer were altered in at least one of the cell lines. The most common genetic changes were gain at 11q and losses at 6q, 9p, and 13q, each present in at least three cell lines. Identification of genetic aberrations by CGH in these cell lines should facilitate the choice of individual cell lines for cloning of genes that are involved in the development and progression of prostate cancer.

Specific cytogenetic aberrations in two novel human prostatic cell lines immortalized by human papillomavirus type 18 DNA

Using chromosome banding and fluorescence in situ hybridization (FISH) with painting probes, sequential cytogenetic analysis was performed of two novel prostate cell lines, PZ-HPV-7 and CA-HPV-10, established by human papillomavirus (HPV) 18 DNA transformation. PZ-HPV-7 originates from a normal diploid prostate epithelial cell strain. PZ-HPV-7 progressed from an initial diploid to a hypertetraploid chromosome number with a relative gain of chromosomes 5 and 20 (7 to 8 copies each). Structural changes were limited; 3p- (2 copies), 3q- (1 copy), and possibly a der(16p;12q). CA-HPV-10 originates from an epithelial cell strain derived from a high-grade human prostate cancer specimen, which showed several karyotypic abnormalities including an extra Y chromosome and double minutes (dmin). In early passage the karyotype of CA-HPV-10 appeared unstable with a decreasing number of cells exhibiting dmin. In late passage the dmin were replaced by a large homogeneously staining region (hsr) on 9p+ marker. The hsr was shown by FISH to be of chromosome 1 origin. The modal number was mainly hypertriploid (72, range 69 to 75). Loss of Y was remarkable (0 to 1 copy). Consistent markers included two copies each of del(1)(q12q31) and der(9)t(1;9)(?;p22), and one der(11)t(4;11) (?;q21). HPV type 18 genomic integration sites were identified on 1p for PZ-HPV-7 and on the 9p+ marker for CA-HPV-10. In conclusion, both PZ-HPV-7 and CA-HPV-10 showed clonal cytogenetic changes. These two cell lines constitute a novel in vitro model to study the mechanisms involved in human prostate carcino-genesis.

Molecular heterogeneity in prostate cancer: can TP53 mutation unravel tumorigenesis?

While prostate cancer is the most common malignant visceral neoplasm of men, its etiology remains largely unknown and its clinical course unpredictable. Molecular genetics of prostate cancer has become a fruitful area of investigation and might provide clues to understanding these phenomena. Mutation of the TP53 tumor suppressor gene (encoding the p53 protein) has been commonly reported as a critical event in human carcinogenesis, but recent findings in prostate cancer research call into question the correlation between TP53 mutation and prognosis for patients with this tumor. Whole-mount analysis has begun to address the histologic significance of the focal evolution of TP53 mutation in a pre-existing cancer and to reveal its role throughout the process of tumor progression. This model might also apply to other tumors.

Genetic changes in prostate cancer

Recent advances in molecular biology have allowed us to understand that it is the accumulation of genetic alterations which leads to each step of tumorigenesis. What the specific alterations may be, however, often varies with each neoplasm. Prostate cancer is somewhat unique in its presentation to the pathologist of a bewildering array of histologies difficult to assign to diagnostic categories and contributing to misinterpretations of underlying molecular events. As with any malignancy, it is of utmost importance to thoroughly analyze and record the genetic aberrations found in prostate cancer with the objective of correlation to the pathology and natural history of the disease. Multiple oncogenes and tumor suppressor genes have been investigated in both clinical and latent cancer using conventional mutational analyses. To probe deeper into these genes and to uncover novel molecular events, genomic tumor DNA were examined using restriction landmark genomic scanning (RLGS), a method which allows the identification and comparison of specific genetic alterations within large segments and multiple samples of DNA at a time. This article reviews what has been identified based on numerous molecular studies, focusing on the genetic alterations peculiar to human prostate cancer.

Location of KAI1 on the short arm of human chromosome 11 and frequency of allelic loss in advanced human prostate cancer

BACKGROUND

We recently isolated the KAI1 gene, a metastasis suppressor gene for prostate cancer, from human chromosome region 11p13-cen-containing rat prostate cancer cells. The present study was performed to further locate the region of the KAI1 gene on the short arm of chromosome 11, and to examine whether loss of this region is significant during progression of human prostate cancer.

METHODS

The small portion of human chromosome 11 (i.e., 11p13-cen) was reintroduced into highly metastatic rat prostate cancer cells by using microcell-mediated chromosome transfer. Loss of heterozygosity (LOH) at polymorphic microsatellite loci on the human chromosome 11 was examined in human prostate cancer tissues.

RESULTS

The minimum region of human chromosome 11 that contained the KAI1 gene was located on the proximal region of 11p11.2 divided by the D11S554 locus. The percentage of LOH or allelic imbalance at the D11S1344 locus, which is located on the same region as the KAI1 locus, in metastasis tissues from autopsy cases who died from metastatic prostate cancer was 70% (7 of 10 informative cases), whereas the percentages in primary tumors from the same cases and from cases with clinically localized prostate cancer were 33% (3 of 9 informative cases) and 8% (1 of 12 informative cases), respectively.

CONCLUSIONS

These findings demonstrate a high frequency of LOH or allelic imbalance at the centromeric region of 11p, which contains the KAI1 gene in advanced prostate cancer.

The relationship between prostatic intraepithelial neoplasia and prostate cancer: critical issues

PURPOSE

Prostatic intraepithelial neoplasia (PIN) is often considered to be a premalignant lesion and the main precursor of invasive carcinoma of the prostate. We evaluated the evidence for and against PIN as a premalignant lesion and determined guidelines for the clinical management of PIN.

MATERIALS AND METHODS

Literature analysis of histopathological, morphometric, phenotypic and molecular genetic evidence of progression and of clinical findings regarding PIN was done. Literature searches were performed on MEDLINE with relevant key words.

RESULTS

PIN, like prostate cancer, occurs most frequently in the peripheral zone of the prostate and is usually located in close proximity to prostate cancer. The relative PIN and prostate cancer volumes vary inversely. Prostate specific antigen in cases of PIN appears to be intermediate between prostate cancer and normal levels, although this elevation may be explained by concomitant prostate cancer or benign prostatic hyperplasia. Deoxyribonucleic acid ploidy in PIN follows the aneuploid proportion as in the concomitant prostate cancer. Prostate cancer and PIN show evidence of loss of putative tumor suppressor genes on chromosome 8p. The clinical relevance of PIN biopsy findings is based on the association of neoplasia and prostate cancer. High grade PIN in core biopsies without concomitant prostate cancer has a substantial risk for prostate cancer in subsequent biopsies (24 to 73%, up to 100% when the digital rectal examination is suspicious) and should cause further biopsy sampling.

CONCLUSIONS

There is convincing evidence that PIN is a precursor lesion to prostate cancer, with a close association of PIN and prostate cancer in biopsy and prostatectomy specimens. A biopsy finding of high grade PIN necessitates further investigation in patients who are candidates for radical treatment for localized prostate cancer.

Cytogenetic studies in prostate cancer: are we making progress?

Prostate cancer is the most commonly diagnosed male malignancy in western countries. Recent work in cell biology and molecular cytogenetics has led to a large amount of data on chromosomal abnormalities in prostatic tumors. A highlight of the literature describing both classical and molecular cytogenetic studies of prostate cancer is presented. By conventional cytogenetics, predominant changes included gain of chromosome 7, loss of Y, deletions of 7q and 10q, and the appearance of double minutes. Using fluorescence in situ hybridization, predominant changes included gains of chromosomes 1, 7, 8, 8q sequences, 17, X and Y, and loss of chromosomes 1, 7, 8, 8p sequences, 10, 10q, 16q and 17q sequences, 17 and Y. Newly defined sites by comparative genomic hybridization included loss of genetic material on 2q, 5q, 6q, 9q, 13q, 15q, 17p, and 18q, and gains at 1q, 2p, 3q, 7q, 9q, 11p, 16p, 20, 22, and X. These data indicate that multiple non-random genomic sites are involved in prostate tumorigenesis. This wide and relatively recent gain of information is likely to provide key clues to the biologic basis of this disease.

Role of proteoglycans in cell adhesion of prostate cancer cells: from review to experiment

Development and progression of prostate cancer is a multistep process of cumulative genetic damage, acquired during a life-time. However, the altered genotype acts against an appropriate background of epigenetic control mechanisms. Several mechanisms of mitotically heritable, epigenetic control of differential gene transcription have been noted, such as stromal-epithelial and cell-cell interactions. In prostate cancer, an important, supporting and/or inhibiting role of stromal-epithelial interaction has been implicated in tumor growth, angiogenesis and metastasis, which includes cell proliferation, adhesion and motility. Within these processes, data mainly obtained in systems other than the prostate have shown a crucial (regulatory) role of proteoglycans (PGs) acting at the level of cell-cell and cell-pericellular matrix interactions. Although little information has been recorded from normal, benign hyperplastic and malignant prostate tissue, PGs are components of both the cell surface and the extracellular matrix (ECM) that form associations with other molecules, such as fibronectin and laminin. On the basis of cell-ECM adhesion/interaction as a prerequisite for both cell proliferation and motility, and the involvement of PGs, the purpose of this study was to investigate the possible biological relevance of (free) glycosaminoglycans (GAGs), as major functional substructures of PGs, on cell adhesion of a series of human prostatic cell lines cultured in vitro. The effects of a series of exogenously applied GAGs on cell adhesion and proliferation were studied in the human cell lines LNCaP, DU 145 and PC-3, cultured on tissue culture plastic as substratum. The applied GAGs were the natural GAGs heparin, heparan, dermatan, chondroitin-4 and chondroitin-6 sulfate, and the semisynthetic, GAG-like pentosan polysulfate (PPS). Addition of GAGs (1-300 micrograms/ml) to cultures that were allowed to adhere for 24 h prior to GAG addition did not affect cell proliferation. In contrast, whereas the natural GAG added during cell adhesion had no effect. PPS strongly inhibited proliferation of LNCaP and DU145, but not the less anchorage-dependent PC-3 cells. Under the latter conditions, after 6 days of culturing the IC50 of proliferation were determined to be < 1 and 50 micrograms PPS/ml for LNCaP and DU145, respectively, corresponding with a profound effect on cell morphology. Direct measurements of cell adhesion confirmed that, in contrast to the natural GAGs, PPS inhibited cell adhesion. In conclusion, the interference of a nonnatural, GAG-like structure with cell adhesion may be interpreted as the involvement of PGs of the cell surface in cell adhesion, possibly affecting the various processes (proliferation, angiogenesis and metastasis) of prostate tumor progression. Although similar interferences of nonnatural GAGs with cell-adhesion-associated proliferation of anchorage-dependent cells remain to be established under in vivo conditions, this type of compounds deserves further attention as a tool with which to study the role of cell adhesion in the progression of prostate cancer and as a potential candidate for the development of a stromal-epithelial targeted therapy.

Combined cytogenetic and molecular genetic analyses of fifty-nine untreated human prostate carcinomas

G-banding analyses and molecular genetic investigations (fluorescence in situ hybridization (FISH) and loss of heterozygosity (LOH) studies) were performed in 59 tumor and nontumorous samples of human prostate carcinoma. Clonal chromosome aberrations were detected in 16 tumors of which nine were poorly differentiated (G3) and 11 in an advanced stage (pT3). Six cases showed numerical chromosome aberrations. The most common numerical aberrations were trisomy 7 and loss of the Y chromosome each present in three tumors. Clonal structural aberrations were detected in 12 tumors. Deletions could be observed in two cases affecting chromosome 6q23 and in two cases affecting chromosomal region 16q. A structural variant of the pericentromeric heterochromatin of chromosome 9 became apparent in six cases. The Y chromosome was involved in clonal translocations in two cases, additionally an inversion occurred on chromosome 19 in one case. All clonal chromosomal changes were found exclusively in the tumor sample. For an analysis of the pericentromeric heterochromatin of chromosome 9, FISH using a chromosome 9-specific sat III DNA probe was carried out on metaphase preparations of tumor and nontumorous tissues of two cases showing var(9)(qh). The FISH data suggest a deletion in the pericentromeric heterochromatin. Loss of heterozygosity studies on chromosomal regions 10q and 16q were carried out because both chromosomes were frequently affected by nonclonal structural aberrations. Loss of heterozygosity could be verified in 11 cases.

Molecular biology of prostatic intraepithelial neoplasia

High-grade PIN is the most likely precursor of prostatic adenocarcinoma, according to virtually all available evidence to date. The clinical importance of recognizing PIN is based on its strong association with prostatic carcinoma. PIN has a high predictive value as a marker for adenocarcinoma. Its identification in biopsy specimens of the prostate warrants further search for concurrent invasive carcinoma. PIN is associated with progressive abnormalities of phenotype and genotype intermediate between normal prostatic epithelium and cancer, indicating impairment of cell differentiation and regulatory control with advancing stages of prostatic carcinogenesis. There is progressive gain or loss of a wide variety of biomarkers, including morphometric markers, differentiation markers, stromal markers, growth factors and associated receptors, oncogenes, tumor suppressor genes, and chromosomes. Abnormalities in expression of most biomarkers are amplified in the progression from high-grade PIN to localized cancer, metastatic cancer, and hormone-refractory cancer. Oncogenesis of prostatic carcinoma probably occurs through the selection of several genetic changes, each modifying the expression or function of genes controlling cell growth and differentiation. Further studies are needed to evaluate the function and prognostic value of oncogene expression in the normal, preneoplastic, and neoplastic prostate.

Gain and loss of chromosomes 1, 7, 8, 10, 18, and Y in 46 prostate cancers

Fluorescence in situ hybridization (FISH) with centromere probes was used to investigate numerical aberrations of chromosomes 1, 7, 8, 10, 18, and Y in 46 prostate carcinoma (PC) and 11 benign prostatic hyperplasia (BPH) samples. None of the benign specimens showed any chromosomal aberration. Forty-one of 46 PC specimens showed numerical aberrations of one or more chromosomes. All investigated chromosomes showed numerical aberrations in at least 30% of the specimens, gain being more frequent than loss. Comparison of DNA flow cytometry (FCM) and FISH results showed that not only aneuploid tumors but also most diploid tumors harbored numerical chromosome aberrations. Chromosome 10 was the most frequently gained (65%), and Y the most frequently lost chromosome (14%). Nonmetastatic and metastatic tumors differed significantly (P < .05) in the number of copies for chromosomes 7, 8, and 10, but not for 1, 18, and Y. These results suggest strongly that gains of chromosomes 7, 8, and 10 are involved in PC progression.