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

TRIM37 contributes to malignant outcomes and CDDP resistance in gastric cancer

Background: TRIM37 (Tripartite Motif Containing 37) is an E3 ubiquitin ligase for histone H2A and inhibits transcription in several genes. However, it is not known whether it plays a role in gastric cancer (GC). In this study, we tested whether TRIM37 acts as a cancer-promoting factor by being overexpressed in GC. Methods: We analyzed GC cell lines and 124 primary tumors, which were curatively resected in our hospital between 2001 and 2003. Results: Overexpression of the TRIM37 protein was detected in almost all GC cell lines and GC samples (76 out of 124 cases) and was significantly correlated with lymphatic and venous invasion, advanced T-Stage, N-Stage, histology and high recurrence rate. Patients with TRIM37 overexpressing tumors had a worse survival rate than those with non-expressing tumors (P=0.0057). Moreover, TRIM37 positivity was identified as an independent factor predicting worse outcomes (P=0.018, Hazard ratio 3.41). The apoptotic cell analysis showed that the knockdown of TRIM37 increased apoptosis in comparison with the control. In TRIM37 overexpressing GC cells, knockdown of TRIM37 suppressed the migration and invasion. Conclusions: TRIM37 plays a crucial role in tumor malignant potential through its overexpression and highlight its usefulness as a prognostic factor and potential therapeutic target in GC.

Tissue is the Issue: Biomarkers of Prognosis and Classification in Adult Gliomas

OBJECTIVE

To explain several biomarkers used in primary adult brain tumor diagnosis and the methodologies for their application.

DATA SOURCES

Peer-reviewed literature.

CONCLUSION

In the past few years, several biomarkers have been touted as providing reliable and objective assays of histogenesis, prognosis, and therapeutic sensitivity. A number of these markers have failed the test of time and rigorous practice applications. More recently, assays with diagnostic applications have been reported and validated from multiple laboratories using large numbers of patients in routine clinical practices.

IMPLICATIONS FOR NURSING PRACTICE

This article provides a reference for biomarker tests for gliomas. There is a greater need for nurses to understand the translational interface between basic science and clinical medicine to determine the applications of these biomarkers for the best interests of their patients.

Overexpression of ZRF1 is related to tumor malignant potential and a poor outcome of gastric carcinoma

Zuotin-related factor 1 (ZRF1) is a recently characterized epigenetic factor involved in transcriptional regulation and is highly overexpressed in several malignancies, but it is not known whether it plays a role in gastric cancer (GC). In this study, we investigated whether ZRF1 acts as a cancer-promoting gene through its activation/overexpression in GC. We analyzed five GC cell lines and 133 primary tumors, which had been curatively resected in our hospital between 2001 and 2003. Overexpression of ZRF1 was detected in GC cell lines (four out of five lines, 80.0%) and was detected in primary tumor samples of GC (52 out of 133 cases, 39.1%) and significantly correlated with differentiated histological type, venous invasion, lymphatic invasion, advanced stage and a higher recurrence rate. ZRF1-overexpressing tumors had a worse survival rate than those with non-expressing tumors (P < 0.01, log-rank test). ZRF1 positivity was independently associated with a worse outcome in the multivariate analysis (P < 0.01; hazard ratio 4.92; 95% confidence interval: 1.6-21.1). In ZRF1-overexpressing GC cells, knockdown of ZRF1 using specific siRNAs inhibited the cell proliferation, migration and invasion and induced apoptosis in a p53-dependent manner. These findings suggest that ZRF1 plays a crucial role in tumor malignant potential through its overexpression and highlight its usefulness as a prognostic factor and potential therapeutic target in GC.

Minimally invasive prostate cancer detection test using FISH probes

Purpose

The ability to test for and detect prostate cancer with minimal invasiveness has the potential to reduce unnecessary prostate biopsies. This study was conducted as part of a clinical investigation for the development of an OligoFISH^® probe panel for more accurate detection of prostate cancer.

Materials and methods

One hundred eligible male patients undergoing transrectal ultrasound biopsies were enrolled in the study. After undergoing digital rectal examination with pressure, voided urine was collected in sufficient volume to prepare at least two slides using ThinPrep. Probe panels were tested on the slides, and 500 cells were scored when possible. From the 100 patients recruited, 85 had more than 300 cells scored and were included in the clinical performance calculations.

Results

Chromosomes Y, 7, 10, 20, 6, 8, 16, and 18 were polysomic in most prostate carcinoma cases. Of these eight chromosomes, chromosomes 7, 16, 18, and 20 were identified as having the highest clinical performance as a fluorescence in situ hybridization test and used to manufacture the fluorescence in situ hybridization probe panels. The OligoFISH^® probes performed with 100% analytical specificity. When the OligoFISH^® probes were compared with the biopsy results for each individual, the test results highly correlated with positive and negative prostate biopsy pathology findings, supporting their high specificity and accuracy. Probes for chromosomes 7, 16, 18, and 20 showed in the receiver operator characteristics analysis an area under the curve of 0.83, with an accuracy of 81% in predicting the biopsy result.

Conclusion

This investigation demonstrates the ease of use with high specificity, high predictive value, and accuracy in identifying prostate cancer in voided urine after digital rectal examination with pressure. The test is likely to have positive impact on clinical practice and advance approaches to the detection of prostate cancer. Further evaluation is warranted.

The complexity of prostate cancer: genomic alterations and heterogeneity

Although prostate cancer is the most common malignancy to affect men in the Western world, the molecular mechanisms underlying its development and progression remain poorly understood. Like all cancers, prostate cancer is a genetic disease that is characterized by multiple genomic alterations, including point mutations, microsatellite variations, and chromosomal alterations such as translocations, insertions, duplications, and deletions. In prostate cancer, but not other carcinomas, these chromosome alterations result in a high frequency of gene fusion events. The development and application of novel high-resolution technologies has significantly accelerated the detection of genomic alterations, revealing the complex nature and heterogeneity of the disease. The clinical heterogeneity of prostate cancer can be partly explained by this underlying genetic heterogeneity, which has been observed between patients from different geographical and ethnic populations, different individuals within these populations, different tumour foci within the same patient, and different cells within the same tumour focus. The highly heterogeneous nature of prostate cancer provides a real challenge for clinical disease management and a detailed understanding of the genetic alterations in all cells, including small subpopulations, would be highly advantageous.

Systems biology approach to stage-wise characterization of epigenetic genes in lung adenocarcinoma

Background

Epigenetics refers to the reversible functional modifications of the genome that do not correlate to changes in the DNA sequence. The aim of this study is to understand DNA methylation patterns across different stages of lung adenocarcinoma (LUAD).

Results

Our study identified 72, 93 and 170 significant DNA methylated genes in Stages I, II and III respectively. A set of common 34 significant DNA methylated genes located in the promoter section of the true CpG islands were found across stages, and these were: HOX genes, FOXG1, GRIK3, HAND2, PRKCB, etc. Of the total significant DNA methylated genes, 65 correlated with transcription function. The epigenetic analysis identified the following novel genes across all stages: PTGDR, TLX3, and POU4F2. The stage-wise analysis observed the appearance of NEUROG1 gene in Stage I and its re-appearance in Stage III. The analysis showed similar epigenetic pattern across Stage I and Stage III. Pathway analysis revealed important signaling and metabolic pathways of LUAD to correlate with epigenetics. Epigenetic subnetwork analysis identified a set of seven conserved genes across all stages: UBC, KRAS, PIK3CA, PIK3R3, RAF1, BRAF, and RAP1A. A detailed literature analysis elucidated epigenetic genes like FOXG1, HLA-G, and NKX6-2 to be known as prognostic targets.

Conclusion

Integrating epigenetic information for genes with expression data can be useful for comprehending in-depth disease mechanism and for the ultimate goal of better target identification.

Chromosome 7q31.1 deletion in myeloid neoplasms

We studied monosomy and deletions of chromosome 7 in 208 patients with myeloid disorders; we found 39 patients (19%) with monosomy or deletion of chromosome 7: 24 patients with chromosome 7 deletion and 15 with monosomy 7. In the 24 patients with chromosome 7 deletions, studied with copy-number variants, short-tandem repeats, microsatellites, single nucleotide polymorphisms, and deletion polymorphisms, the most common deleted region was 7q31.1 (20 patients). Deletion polymorphism studies performed in these 20 patients showed an interstitial deletion of at least 140 kilobase in 6 patients; the deletion spans between the genes forkhead box P2 and Myo D family inhibitor domain containing. Because both genes do not seem to be involved in leukogenesis, we suggest to look carefully into this deletion for the presence of tumor suppressor genes and microRNAs.

Cytogenomic aberrations associated with prostate cancer

Genetic changes associated with prostate cancer have finally begun to elucidate some of the mechanisms involved in the etiology of this complex and common disease. We highlight consistent and relatively frequent abnormalities seen by various methodologies. Specifically, the results of conventional and molecular cytogenetic studies, genome-wide association studies with single nucleotide polymorphisms, recurrent gene fusions, and epigenetic analyses are discussed.

[Development of a three-dimensional primary prostate cancer cell culture model]

Much prostate cancer research is based on cell culture results. Recent genomic studies found major differences between primary prostate cancer tissue and established prostate cancer cell lines, which calls into question the clinical relevance of study results based on cell cultures.Using primary cultures of prostate cancer cells from prostatectomy specimens seems to be a reasonable solution, but primary cell cultures are much more difficult to establish. In this study, a primary cell culture model was combined with an invasion assay. With this combination it was possible not only to select invasive cell clones from the primary culture but also to culture these cells in a three-dimensional model, forming spheroids. A further characterization of this cell population was done by comparative genomic hybridization, showing numerous genetic alterations. The presented cell culture model offers, for the first time, an opportunity to isolate invasive growing cells from primary prostate cancer tissue and cultivate these cells for further analyses.

Genetic profile identification in clinically localized prostate carcinoma

PURPOSE

To confirm our previously obtained results, we genetically characterized prostate cancer from patients undergo radical prostatectomy in a retrospective study.

MATERIALS AND METHODS

Histological sections were evaluated for 106 patients treated with surgery from 1991 to 2004. With fluorescence in situ hybridization (FISH) method, the status of LPL (8p22), c-MYC (8q24) genes and 7, 8, X chromosomes was evaluated.

RESULTS

Chromosomes 7, 8, X aneusomy was demonstrated in 91.5%, 78.3%, and 51.9% of the samples, respectively, whereas LPL deletion and MYC amplification were found in 76.0% and 1.6%. A genetic profile was considered as unfavorable when at least two aneusomic chromosomes and one altered gene were present. Tumors with an adverse genetic profile were more frequently present in patients with higher stages (P = 0.02), biochemical/clinical progression (P = 0.03), and Gleason grade 4 + 3 (P = 0.02). Multiple correspondence analysis identified one tumor group characterized by chromosome 8 aneusomy, X polysomy, LPL gene deletion, Gleason > 7 and 4 + 3 associated with progression.

CONCLUSIONS

In this study, we recognized the predictive power of previously identified cytogenetic profiles. Assessment of genetic set may characterize each patient and have influence on postoperative therapeutic strategies.

Gene amplification and mutation analysis of epidermal growth factor receptor in hormone refractory prostate cancer

BACKGROUND

Amplification and mutation of the epidermal growth factor receptor (EGFR) and Her-2 genes were analyzed in both hormone sensitive and hormone refractory prostate cancer (HRPC).

METHODS

Gene amplifications of EGFR and Her-2 were analyzed by fluorescence in situ hybridization (FISH) with direct sequencing. Studies were performed on a total of 10 patients; tissues were sampled at the time of initial diagnosis and after the conversion to HRPC (a total of 20 tissue samples). Direct sequencing was performed on exons 18-24 of EGFR and exons 19 and 20 of Her-2. Amplification and mutation were compared with clinicopathologic features.

RESULTS

Gene amplification of EGFR was observed in 6 (30%) out of 20 samples. A total of six EGFR mutations in exons 18 and 19 were detected in three pairs of tissues (three patients). One patient, with hormone refractory status, had a novel deletion mutation in EGFR exon 19. EGFR mutations were associated with the acinar type of prostate cancer but were not associated with the ductal type. No significant correlation was found between mutation change and hormone sensitive or refractory status. However, the time to convert to HRPC was significantly shorter in the patients with a mutation in the EGFR gene (P = 0.017). There were no Her-2 gene amplifications or mutations found in any of the samples.

CONCLUSIONS

EGFR gene mutation and amplification occurred frequently in advanced prostate cancer cases. EGFR mutations do not appear to play a significant role in the hormone refractory pathway but are associated with prognosis.

MAGI-2 Inhibits cell migration and proliferation via PTEN in human hepatocarcinoma cells

MAGI-2, a multidomain scaffolding protein, contains nine potential protein-protein interaction modules, including a GuK domain, two WW domains and six PDZ domains. In this study, we examined eight human hepatocarcinoma cell lines (HHCCs) and found that MAGI-2 was expressed only in 7721 cells. After 7721, 7404 and 97H cells were transfected with myc-MAGI-2 plasmid, their migration and proliferation was significantly inhibited, which was associated with downregulation of p-FAK and p-Akt. It is known that p-FAK is a substrate of PTEN and p-Akt can be regulated by PTEN via PIP(3). We demonstrated that PTEN was upregulated after myc-MAGI-2 transfection, which was due to the enhancement of PTEN protein stability rather than mRNA levels. Furthermore, MAGI-2-induced inhibition of cell migration and proliferation was attenuated in 7721 cells with PTEN silence or in PTEN-null cell line U87MG, and PTEN transfection could restore the effect of MAGI-2 in U87MG cells. Finally, the molecular association between PTEN and MAGI-2 was confirmed. Our results suggested that PTEN played a critical role in MAGI-2-induced inhibition of cell migration and proliferation in HHCCs.

Association of a CAV-1 haplotype to familial aggressive prostate cancer

BACKGROUND

Multiple lines of evidence have implicated the CAV-1 gene in prostate cancer progression. CAV-1 is located within the prostate cancer aggressiveness locus at 7q31-33, and was identified as being overexpressed in prostate tumors. Mutation screening was performed as well as a case-control study to examine if polymorphisms in CAV-1 are associated with prostate cancer aggressiveness in a German population.

METHODS

We sequenced the CAV-1 promoter region and its open reading frame in prostate cancer families with linkage to chromosome 7q31-33. Additionally, 105 unrelated familial prostate cancer probands, 190 sporadic cases, and 191 controls were genotyped at four intronic single nucleotide polymorphisms. Resulting haplotypes were tested for association using age at diagnosis, tumor grade, TNM stage, and follow up information to stratify for aggressive disease.

RESULTS

No mutation was found in the CAV-1 coding region or in the promoter. One of the 11 observed haplotypes showed an increased frequency in cases with high tumor stage (P = 0.03).

CONCLUSIONS

This is the first report providing evidence for CAV-1 being involved in predisposition to aggressive prostate cancer. The association of a potential risk haplotype agrees well with a role of CAV-1 in tumor progression but needs further confirmation.

Multiple abnormalities detected by dye reversal genomic microarrays in prostate cancer: a much greater sensitivity than conventional cytogenetics

Prostate cancer remains the most common male malignancy in Western countries, yet limited information exists regarding genetic changes and clinical correlations. The advent of comparative genomic hybridization microarray (GM) technology has recently allowed for precise screening of DNAs for genetic copy number changes; this offers an advantage over previous techniques, including conventional cytogenetics. A problem with cytogenetic prostate cancer analysis has been the study of the appropriate cell types because this is a highly heterogeneous tumor. We have performed GM using the Spectral Genomics Inc. dye reversal platform on 20 primary prostate tumors. These tumor samples were from frozen tissue collected over the last 10 years and multiple clinical parameters, including follow-up were collected on these patients; cytogenetic analysis was previously attempted on all patients. Eighty percent (16/20) of specimens showed copy number changes, 65% of which were losses and 35% were gains of genetic material. The most common changes observed were loss of an interstitial region of 2q (8 cases, 40%), followed by loss of interstitial 6q (6 cases, 30%), loss at 8p and 13q (5 cases each, 25%), gain at 3p and loss at 5q, 16q, and Xq (4 cases each, 20%), and gain at 8p (3 cases, 15%). There was evidence of correlation of loss at 5q with a positive node status. Cytogenetic studies on these same patients only detected clonal changes in 40% (8/20) specimens and did not detect the majority of abnormalities seen by the GM technique. We propose this technology for the evaluation of prostate and other heterogeneous cancers as a rapid and efficient way to detect genetic copy number changes.

Human prostate cancer risk factors

Prostate cancer has the highest prevalence of any nonskin cancer in the human body, with similar likelihood of neoplastic foci found within the prostates of men around the world regardless of diet, occupation, lifestyle, or other factors. Essentially all men with circulating androgens will develop microscopic prostate cancer if they live long enough. This review is a contemporary and comprehensive, literature-based analysis of the putative risk factors for human prostate cancer, and the results were presented at a multidisciplinary consensus conference held in Crystal City, Virginia, in the fall of 2002. The objectives were to evaluate known environmental factors and mechanisms of prostatic carcinogenesis and to identify existing data gaps and future research needs. The review is divided into four sections, including 1) epidemiology (endogenous factors [family history, hormones, race, aging and oxidative stress] and exogenous factors [diet, environmental agents, occupation and other factors, including lifestyle factors]); 2) animal and cell culture models for prediction of human risk (rodent models, transgenic models, mouse reconstitution models, severe combined immunodeficiency syndrome mouse models, canine models, xenograft models, and cell culture models); 3) biomarkers in prostate cancer, most of which have been tested only as predictive factors for patient outcome after treatment rather than as risk factors; and 4) genotoxic and nongenotoxic mechanisms of carcinogenesis. The authors conclude that most of the data regarding risk relies, of necessity, on epidemiologic studies, but animal and cell culture models offer promise in confirming some important findings. The current understanding of biomarkers of disease and risk factors is limited. An understanding of the risk factors for prostate cancer has practical importance for public health research and policy, genetic and nutritional education and chemoprevention, and prevention strategies.

Linkage of aggressive prostate cancer to chromosome 7q31-33 in German prostate cancer families

It has been suggested that chromosome 7q32 contains genes that influence the progression of prostate cancer from latent to invasive disease. In an attempt to confirm this linkage to prostate cancer aggressiveness, 100 German prostate cancer families were genotyped using a panel of eight polymorphic markers on chromosome 7q. We used a multipoint allele sharing method based upon a likelihood ratio test implemented in GENEHUNTERPLUS v1.2 in order to calculate the nonparametric Z(lr) and the associated LOD scores. We applied the aggressiveness of prostate cancer given by the pathological tumour grade of each individual, and the mean age of onset of a family as covariates, and constructed two weighted models. The first (weight(0-1) model) puts weights on families with at least two cases of GIII prostate cancer. The second (weight(0-2) model) also adds weights to families with early and late onset cancer respectively. The unweighted analysis gave no evidence of linkage to chromosome 7q. The Z(lr) scores increased when including the covariates, to 2.60 (P=0.005) using the weight(0-1) and to 3.02 (P=0.001) using the weight(0-2) model for late onset prostate cancer. The associated LOD scores were respectively 1.47 (P=0.009) and 1.98 (P=0.002). The markers that gave most evidence for linkage were exactly in the range of the published prostate cancer aggressiveness region. Our results support a widespread relevance of this locus and suggest that aggressive and late onset prostate cancer is linked to chromosme 7q31-33 in the German population.

High-throughput molecular profiling of high-grade astrocytomas: the utility of fluorescence in situ hybridization on tissue microarrays (TMA-FISH)

Due to recent biological and technical advances, the list of potentially useful candidate genes is rapidly expanding in the study of brain tumors. However, traditional methods of screening individual genes in individual samples are slow and tedious, often with consumption of precious resources after only a few experiments. This study evaluates the feasibility of high-throughput molecular analysis using fluorescence in situ hybridization (FISH) on glioma tissue microarrays (TMA). A single microarray paraffin block was constructed using 65 WHO grade III and IV astrocytomas, sampled in duplicate with 0.6-mm-diameter punch cores. FISH was used to detect common alterations, such as EGFR amplification, chromosome 7, 9, and 10 aneusomies and deletions of 1p, 19q, PTEN, DMBT1, and p16. Of 585 hybridization sets, 508 (87%) yielded interpretable data, with hybridization failure in 33 (5.5%) and dislodged tissue in 44 sets (7.5%), respectively. Glioblastomas harbored significantly more alterations than anaplastic astrocytomas, with the overall frequencies of alterations similar to those reported using other techniques. The overall concordance rate between paired tumor core samples was 93%. We conclude that TMA-FISH is an efficient and reliable method for detecting molecular alterations in high-grade astrocytomas.

Cytogenetics and molecular genetics of cancer of the prostate

Prostate cancer remains the most common male malignancy in Western countries and the second-leading cause of death from cancer in males. Progress in the understanding of molecular and genetic mechanisms leading to this disease has only recently begun to offer a glimpse of the genes, chromosomal sites, and proteins implicated in the development and progression of prostate tumors. This brief review addresses some of the key issues in prostate cancer research, including a discussion of both hereditary and sporadic cancers as well as specific genes and chromosomal loci that likely play a part in the etiology of this disease.

Differential NF1, p16, and EGFR patterns by interphase cytogenetics (FISH) in malignant peripheral nerve sheath tumor (MPNST) and morphologically similar spindle cell neoplasms

Malignant peripheral nerve sheath tumors (MPNSTs) are diagnostically challenging neoplasms for which sensitive and specific immunohistochemical markers are lacking. Although limited to date, previous studies have suggested that NF1 (17q), NF2 (22q), p16 (9p), and EGFR (7p) alterations may be involved in MPNST tumorigenesis. To determine whether specific genetic changes differentiate between MPNST and morphologically similar neoplasms, we assessed these chromosomal regions in 22 MPNSTs (9 NF1-associated, 13 sporadic), 13 plexiform neurofibromas, 5 cellular schwannomas, 8 synovial sarcomas, 6 fibrosarcomas, and 13 hemangiopericytomas by 2-color FISH. NF1 deletions, often in the form of monosomy 17, were found in MPNSTs (76%). neurofibromas (31%), hemangiopericytomas (17%), and fibrosarcomas (17%), but not in synovial sarcomas or cellular schwannomas. NF1 losses were encountered more frequently in MPNSTs versus other sarcomas (p < 0.001), as were p16 homozygous deletions (45% vs 0%; p < 0.001), EGFR amplifications (26% vs 0%; p = 0.006), and polysomies for either chromosomes 7 (53% vs 12%; p = 0.003) or 22 (50% vs 4%; p < 0.001). Hemizygous or homozygous p16 deletions were detected in 75% of MPNSTs, but not in benign nerve sheath tumors (p < 0.001). Thus, FISH analysis identifies relatively specific genetic patterns that may be useful in selected cases, for which the differential diagnosis includes low- or high-grade MPNST.

Aneusomy of chromosomes 7, 8, and 17 and amplification of HER-2/neu and epidermal growth factor receptor in Gleason score 7 prostate carcinoma: a differential fluorescent in situ hybridization study of Gleason pattern 3 and 4 using tissue microarray

Recent evidence shows that the proportion of poorly differentiated prostate carcinoma (Gleason pattern [GP] 4/5) is a surrogate factor for biochemical failure after radical prostatectomy (RP). However, little is known about specific molecular and cytogenetic changes in this aggressive component of localized prostate cancer. We constructed a tissue microarray containing areas of GP 3 and 4 from formalin-fixed radical prostatectomy specimens of 39 patients with Gleason score 7 carcinoma (>or=50% GP 4), known pathologic staging parameters (stage < T3b), and biochemical failure data (mean follow-up, 30 months; range, 5 to 74 months). Interphase fluorescent in situ hybridization (FISH) was performed on 5-microm microarray sections using pericentromeric probes to chromosomes 7, 8, and 17 and probes for the HER-2/neu and epidermal growth factor receptor (EGFR) genes. Low-level amplification of HER-2/neu was found in 26% of cases (3 to 5 signals per nucleus, corrected for chromosome 17 aneusomy). Aneusomy of chromosomes 7, 8, and 17 was identified in 21%, 15%, and 5% of cases, respectively. All aberrations occurred almost exclusively in GP 4 carcinoma (8 of 8 aneusomies 7, 2 of 2 trisomies 17, 9 of 10 HER-2/neu amplifications, and 5 of 6 aneusomies 8; P < .001). The presence of HER-2/neu amplification was associated with high tumor volume (>2.0 cm(3), P = 0.004). Among patients with negative surgical margins, gain of chromosome 7 was associated with biochemical failure after RP (P =.004, log-rank). Amplification of the EGFR gene occurred in only 1 case (3%). Significant differences in HER-2/neu amplification and gain of chromosomes 7, 8, and 17 were detected between GP 4 prostate carcinoma and GP 3. The frequency of aberrations increased with tumor volume. Chromosome 7 abnormalities may play an important role in cancer progression in margin-negative patients. EGFR amplification was rare, suggesting that this oncogene is not altered at the gene copy number level.

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.

Novel amplification unit at chromosome 3q25-q27 in human prostate cancer

BACKGROUND

In prostate carcinoma, amplification of the genes c-MYC, Her2/NEU, and the androgen receptor gene has been documented, with gene amplification being related to progressive tumor growth. Recently, using comparative genomic hybridization (CGH), we provided evidence for DNA copy number gains at chromosome 3q25-q26 in prostate cancer [Sattler et al.: Prostate 39:79-86, 1999].

METHODS

In this study, additional prostatic tumors were evaluated by CGH to determine the frequency of DNA overrepresentation at 3q. Comparative PCR and Southern blot analyses were applied to determine whether known genes are involved in DNA copy number gains.

RESULTS

By CGH, DNA copy number gains, all of which involved chromosome region 3q25-q26, were disclosed in 50% of the prostate tumors analyzed. There was no evidence for high-level amplification. The analysis of 12 genes from 3q25-q27 by comparative PCR revealed amplification in 6 (35.3%) of 17 tumors tested. Amplification was detected for the genes IL12A, MDS1, SLC2A2, and SOX2, with coamplification of three genes in two tumors. IL12A was amplified as single gene in three tumors and in a subline of the DU145 cell line, SLC2A2 in one tumor.

CONCLUSIONS

Our studies revealed a novel amplification unit at 3q25-q27 in prostate carcinoma, with the genes IL12A, MDS1, SLC2A2, and SOX2 being located within the amplification unit. A common region of amplification was evident spanning the IL12A gene locus at 3q25-q26.2. Possibly, IL12A indicates an adjacent, till now unidentified gene which is important in the development of prostate cancer.

Evidence for regulation of the PTEN tumor suppressor by a membrane-localized multi-PDZ domain containing scaffold protein MAGI-2

PTEN is a tumor suppressor gene mutated in human cancers. Although many mutations target the phosphatase domain, others create a truncated protein lacking the C-terminal PDZ-binding motif or a protein that extends beyond the PDZ-binding motif. Using the yeast two-hybrid system, we isolated a membrane-associated guanylate kinase family protein with multiple PDZ domains [AIP-1 (atrophin interacting protein 1), renamed MAGI-2 (membrane associated guanylate kinase inverted-2)]. MAGI-2 contains eight potential protein-protein interaction domains and is localized to tight junctions in the membrane of epithelial cells. PTEN binds to MAGI-2 through an interaction between the PDZ-binding motif of PTEN and the second PDZ domain of MAGI-2. MAGI-2 enhances the ability of PTEN to suppress Akt activation. Furthermore, certain PTEN mutants have reduced stability, which is restored by adding the minimal PDZ-binding motif back to the truncated protein. We propose that MAGI-2 improves the efficiency of PTEN signaling through assembly of a multiprotein complex at the cell membrane.

A new human prostate carcinoma cell line, 22Rv1

A cell line has been derived from a human prostatic carcinoma xenograft, CWR22R. This represents one of very few available cell lines representative of this disease. The cell line is derived from a xenograft that was serially propagated in mice after castration-induced regression and relapse of the parental, androgen-dependent CWR22 xenograft. Flow cytometric and cytogenetic analysis showed that this cell line represents one hyper DNA-diploid stem line with two clonal, evolved cytogenetic sublines. The basic karyotype is close to that of the grandparent xenograft, CWR22, and is relatively simple with 50 chromosomes. In nude mice, the line forms tumors with morphology similar to that of the xenografts, and like the parental CWR22 and CWR22R xenografts, this cell line expresses prostate specific antigen. Growth is weakly stimulated by dihydroxytestosterone and lysates are immunoreactive with androgen receptor antibody by Western blot analysis. Growth is stimulated by epidermal growth factor but is not inhibited by transforming growth factor-beta1.

Chromosomal clues to the development of prostate tumors

BACKGROUND

Cytogenetic, molecular cytogenetic, and molecular studies of prostate cancer have revealed an enormous amount of data regarding chromosomal loci that are aberrant in prostate tumors.

METHODS

These data have been compared and condensed in this review to determine which chromosomes and chromosome sites have been most frequently reported.

RESULTS

Loss of the Y chromosome, gain of 7, 8, and X, and interstitial deletions on 6q, 7q, 8p, 10q, 13q, 16q, 17q, and 18q are the most prevalent.

CONCLUSIONS

A potential model for genetic control of tumor progression is presented, as are data regarding the evaluation of a new series of tumors.