Sandra M. Gaston

Prevalence of TMPRSS2-ERG Fusion Prostate Cancer among Men Undergoing Prostate Biopsy in the United States

Purpose: Fusion of the TMPRSS2 prostate-specific gene with the ERG transcription factor is a putatively oncogenic gene rearrangement that is commonly found in prostate cancer tissue from men undergoing prostatectomy. However, the prevalence of the fusion was less common in samples of transurethral resection of the prostate from a Swedish cohort of patients with incidental prostate cancer followed by watchful waiting, raising the question as to whether the high prevalence in prostatectomy specimens reflects selection bias. We sought to determine the prevalence of TMPRSS2-ERG gene fusion among prostate-specific antigen–screened men undergoing prostate biopsy in the United States. Experimental Design: We studied 140 prostate biopsies from the same number of patients for TMPRSS2-ERG fusion status with a fluorescent in situ hybridization assay. One hundred and thirty-four samples (100 cancer and 34 benign) were assessable. Results:ERG gene rearrangement was detected in 46% of prostate biopsies that were found to have prostate cancer and in 0% of benign prostate biopsies (P < 0.0001). Evaluation of morphologic features showed that cribriform growth, blue-tinged mucin, macronucleoli, and collagenous micronodules were significantly more frequent in TMPRSS2-ERG fusion–positive prostate cancer biopsies than gene fusion–negative prostate cancer biopsies (P ≤ 0.04). No significant association with Gleason score was detected. In addition, non-Caucasian patients were less likely to have positive fusion status (P = 0.02). Conclusions: This is the first prospective North American multicenter study to characterize TMPRSS2-ERG prostate cancer prevalence in a cohort of patients undergoing needle biopsy irrespective of whether or not they subsequently undergo prostatectomy. Our results show that this gene rearrangement is common among North American men who have prostate cancer on biopsy, is absent in benign prostate biopsy, and is associated with specific morphologic features. These findings indicate a need for prospective studies to evaluate the relationship of TMPRSS2-ERG rearrangement with clinical course of screening-detected prostate cancer in North American men, and a need for the development of noninvasive screening tests to detect TMPRSS2-ERG rearrangement.

Determinations of prostate volume at 3-Tesla using an external phased array coil: comparison to pathologic specimens.

RATIONALE AND OBJECTIVES To compare techniques for measuring in vivo prostate volumes using torso phased-array imaging at 3-Tesla. METHODS Eleven patients imaged at 3-Tesla with a torso-phased array coil using multiplanar fast spin echo (FSE) T2-weighted imaging who underwent radical prostatectomy comprised the study population. Surgical specimens were imaged. The pathologic specimen volume was compared with varieties of magnetic resonance volume determinations, the latter using ellipsoid and planimetric assessments. Three-dimensional images of the excised prostate were generated. Linear correlation coefficients were calculated comparing volume determinations from image data and pathologic data. RESULTS Correlation coefficient (r2) values from the ellipsoid formula among six different data sets ranging between 0.325 to 0.751; the highest in vivo r2 value was obtained by multiplying the anterior-posterior and the superior-inferior dimensions from the sagittal image by the right-left dimension from the axial image. The r2 values of the planimetric volume and specimen 3-dimensional volume rendering were 0.652 and 0.86, respectively. CONCLUSIONS Surface coil prostate imaging at 3-Tesla provides undistorted images for volume assessment and in vivo volume determinations very close to ex vivo imaging volume determinations.

Genetic heterogeneity of gene defects responsible for familial Alzheimer disease.

Inherited Alzheimers disease is a genetically heterogeneous disorder that involves gene defects on at least five chromosomal loci. Three of these loci have been found by genetic linkage studies to reside on chromosomes 21, 19, and 14. On chromosomes 21, the gene encoding the precursor protein of Alzheimerassociated amyloid (APP) has been shown to contain several mutations in exons 16 and 17 which account for roughly 2–3% of familial Alzheimers disease (FAD). The other loci include what appears to be a susceptibility gene on chromosome 19 associated with late-onset (>65 years) FAD, and a major early-onset FAD gene defect on the long arm of chromosome 14. In other early-and late-onset FAD kindreds, the gene defects involved do not appear to be linked to any of these three loci, indicating the existence of additional and as of yet unlocalized FAD genes. This review provides a historical perspective of the search for FAD gene defects and summarizes the progress made in world-wide attempts to isolate and characterize the genes responsible for this disorder.

An illustration of the potential for mapping MRI/MRS parameters with genetic over-expression profiles in human prostate cancer

IntroductionMagnetic resonance imaging (MRI) and MR spectroscopy can probe a variety of physiological (e.g. blood vessel permeability) and metabolic characteristics of prostate cancer. However, little is known about the changes in gene expression that underlie the spectral and imaging features observed in prostate cancer. Tumor induced changes in vascular permeability and angiogenesis are thought to contribute to patterns of dynamic contrast enhanced (DCE) MRI images of prostate cancer even though the genetic basis of tumor vasculogenesis is complex and the specific mechanisms underlying these DCEMRI features have not yet been determined.Materials and MethodsIn order to identify the changes in gene expression that correspond to MRS and DCEMRI patterns in human prostate cancers, we have utilized tissue print micropeel techniques to generate “whole mount” molecular maps of radical prostatectomy specimens that correspond to pre-surgical MRI/MRS studies. These molecular maps include RNA expression profiles from both Affymetrix GeneChip microarrays and quantitative reverse transcriptase PCR (qrt-PCR) analysis, as well as immunohistochemical studies.ResultsUsing these methods on patients with prostate cancer, we found robust over-expression of choline kinase a in the majority of primary tumors. We also observed overexpression of neuropeptide Y (NPY), a newly identified angiogenic factor, in a subset of prostate cancers, visualized on DCEMRI.ConclusionThese studies set the stage for establishing MRI/MRS parameters as validated biomarkers for human prostate cancer.

Genetic and physical mapping of the GLUR5 glutamate receptor gene on human chromosome 21

Glutamate receptors (GluRs) mediate excitatory neurotransmission and may have important roles in central nervous system disorders. To characterize the human GLUR5 gene, which is located on human chromosome 21q22.1, we isolated cDNAs, genomic phage lambda clones, and yeast artificial chromosomes (YACs) and developed sequence tagged sites (STSs) and simple sequence length polymorphisms (SSLPs) for GLUR5. Genetic mapping with a tetranucleotide AGAT repeat named GLUR5/AGAT (six alleles observed, 70% heterozygosity) placed GLUR5 5 cM telomeric to APP (D21S210) and 3cM centromeric to SOD1 (D21S223). The humanGLUR5 gene is located near the familial amyotrophic lateral sclerosis (FALS) locus; linkage analysis of GLUR5 SSLPs in FALS pedigrees yielded negative lod scores, consistent with the recent association of the FALS locus with the SOD1 gene. Physical mapping of GLUR5 using a YAC contig suggested that the GLUR5 gene spans approximately 400–500kb, and is within 280kb of D21S213. The large size of the GLUR5 gene raises questions regarding its functional significance. Our GLUR5 YAC contig includes clones found in the Genethon chromosome 21 YAC contig, and reference to the larger contig indicates the orientation centromere — D21S213 — GLUR5 5′ end-GLUR5/ AGAT — GLUR5 3′ end — SODI. The development of GLUR5/AGAT should permit rapid determination of the status of the GLUR5 gene in individuals with partial trisomy or monosomy of chromosome 21. Such studies may provide insights concerning the possible role of GLUR5 in Down syndrome.

Isolation, characterization, and mapping of gene encoding dihydrolipoyl succinyltransferase (E2k) of humanα-ketoglutarate dehydrogenase complex

We have isolated and sequenced cDNAs representing the full-length (2987-bp) gene for dihydrolipoyl succinyltransferase (E2k component) of the humanα-ketoglutarate dehydrogenase comple (KGDHC) from a human fetal brain cDNA library. The E2k cDNA was mapped to human chromosome 14 using a somatic cell hybrid panel, and more precisely to band 14q24.3 by in situ hybridization. This cDNA also cross-hybridized to an apparent E2k pseudogene on chromosome 1p31. Northern analysis revealed the E2k gene to be ubiquitously expressed in peripheral tissues and brain. Interestingly, chromosome 14q24.3 has recently been reported to contain gene defects for an early-onset form of familial Alzheimers disease and for Machado-Joseph disease. Future studies will be necessary to determine whether the E2k gene plays a role in either of these two disorders.

Epigenetic risk score improves prostate cancer risk assessment

Early detection of aggressive prostate cancer (PCa) remains crucial for effective treatment of patients. However, PCa screening remains controversial due to a high rate of overdiagnosis and overtreatment. To better reconcile both objectives, more effective methods for assessing disease severity at the time of diagnosis are needed.

The Diverse Molecular Nature of Inherited Alzheimer’s Disease

Alzheimer’s diseases (AD) is a major health problem which will continue to intensify in magnitude as the elderly in the population continue to increase in number. The age at which AD strikes is variable, ranging from the fourth to tenth decades, with the greatest proportion of cases occurring in the seventh and eighth decades. A genetic component of this disorder has been strongly indicated by family and survey studies, as well as life table analyses (reviewed in St George-Hyslop et al. 1989). Genetic linkage and association studies of kindreds displaying evidence for familial AD (FAD) have led to the localization of gene defects responsible for this genetically heterogeneous disorder on chromosomes 14, 19 and 21. In a small set of FAD kindreds, mutations have been found in the amyloid beta protein precursor (APP) gene. Yet, the available data indicate that the identity of the genes responsible for the majority of late-onset (> 65 years) as well as early-onset inherited AD remain unknown. Powerful and novel advances in the methodology available for performing genetic linkage analyses on genetically complex disorders have made it feasible to scan the entire human genome in a relatively fast and easy manner for the purpose of localizing the genes responsible for, or predisposing to, inherited AD. Here we describe progress on attempts to further localize and identify various FAD gene defects throughout the genome, with special emphasis on the major early-onset gene defect residing on the long arm of chromosome 14.

Nitrocellulose tissue prints: an innovative approach to preparing high quality DNA and RNA from prostate biopsies without compromising the cores for pathology diagnosis

Much of the research that has been done on prostate cancer tissue biomarkers has relied on radical prostatectomies for biospecimens. However, it is well recognized that important groups of patients are under-represented or missing entirely from biorepository collections of radical prostatectomy specimens. Using prostate biopsy tissues for molecular biomarker research significantly expands the range of available patients to include men whose biopsies show no cancer as well as men who are treated non-surgically or who choose active surveillance. However, one of the challenges of biopsy-based biomarker research is the limited amount of tissue that can be obtained from each core. To address this challenge, we have developed and fully implemented innovative biopsy tissue print technologies that allow us to obtain high quality RNA and DNA from each biopsy core without compromising the specimen for a pathologic diagnosis. Prostate biopsy tissue print samples have been successfully utilized for gene expression profiling, genotyping, DNA methylation and sequencing analyses. Emerging biopsy tissue print applications include studies using viable cells to study tumor metabolism and drug response.

MP29-15 MAKE IT FROM SCRATCH OR HAVE IT DELIVERED? SATISFYING THE FATTY ACID DEMAND OF PROSTATE CANCER

INTRODUCTION AND OBJECTIVES: Macrophage inhibitory cytokine-1 (MIC-1) is a divergent member of the transforming growth factor-b family. We previously reported that high-fat diet (HFD) induced prostate cancer progression through the upregulation of MIC1 in cancer cells. Here, we investigated the role of MIC-1 in controlling tumor microenvironment in HFD-induced prostate cancer progression. METHODS: PC-3M-luc-C6 cells were intraperitoneally injected into BALB/c-nu/nu mice, and equal numbers of mice were categorized into HFD and controlled diet (CD) groups. The extent of tumor burden was detected using the IVIS imaging system, and expression of MIC, proportion of stromal cells in tumors, serum level of MIC-1, and cytokine profile were examined. In vitro, functional analyses in PC-3 cells cultured with prostate stromal cell (PrSC) condition medium, recombinant MIC-1, and cytokine-blocking antibodies were performed. In humans, the relationship between serum level of MIC-1, MIC-1 expression in surgically resected prostate tissues, and clinicopathological parameters were assessed. RESULTS: The mean luciferase activity in mice at 4 weeks was significantly higher in the HFD group than in the CD group (p < 0.01). In the HFD group, MIC-1 expression and alpha smooth muscle actin (aSMA)-positive cells significantly increased in tumors, and serum levels of MIC-1 and IL-8 were significantly elevated. In vitro, recombinant MIC-1 (rMIC-1) induced PrSCs to secrete proinflammatory cytokines, including IL-8 and IL-6, and activate ERK in addition to the directly stimulate cancer cell proliferation and invasion. PrSCs and rMIC-1 increased the invasive capacity of PC-3 cells; however, the effects were impaired by IL-6 and IL-8 capture antibody. Patients with high staining scores of aSMA had significantly higher stage tumors (1⁄4pT2a) than those with low staining scores of aSMA (p 1⁄4 0.031), and the serum level of MIC-1 tended to be higher in patients with high staining scores of aSMA (p 1⁄4 0.056). CONCLUSIONS: MIC-1 stimulates stromal cytokine production in HFD-induced prostate cancer progression. MIC-1 and tumor stromal microenvironment may have implications in the prevention and treatment of HFD-induced prostate cancer progression.