High-risk prostate cancer: A disease of genomic instability

Amplification of different satellite-DNAs in prostate cancer

In various solid tumors and corresponding cell lines, prior research has identified acquired copy number variations (CNVs) encompassing centromeric satellite-DNA sequences. This observation emerged from the application of centromeric probes (satellite-DNA) as controls in molecular cytogenetic investigations and diagnostics, although these accounts were largely anecdotal. In this study, we conducted a systematic screening for satellite-DNA sequence amplification in 31 prostate cancer (PCa) samples, a prevalent malignancy in men characterized by discernible molecular cytogenetic aberrations. Notably, PCa-typical genetic aberrations, such as TMPRSS2-ERG gene rearrangements and PTEN deletion, were identified in 12 and 6 out of the 31 PCa samples, respectively. Overall, PCa exhibited genomic instability marked by chromosomal gain or loss of signals across nearly all tested satellite-DNA regions, with particular emphasis on the Y-chromosome (18/31 cases). Remarkably, 5/12 PCa samples representing more advanced metastatic cancer displayed amplification of one or two satellite DNA stretches each, being detectable as blocks analogous to homogenously staining regions. Notably, these stretches included α-satellite DNA derived from chromosomes 2, 3, 4, 15, and 20, as well as satellite-III DNAs (D1Z1 and DYZ1). These findings align with recent discoveries indicating that α-satellite DNAs are expressed as long-non-coding RNAs in advanced cancer, particularly in the context of PCa.

Elevated APE1 Dysregulates Homologous Recombination and Cell Cycle Driving Genomic Evolution, Tumorigenesis, and Chemoresistance in Esophageal Adenocarcinoma

BACKGROUND & AIMS

The purpose of this study was to identify drivers of genomic evolution in esophageal adenocarcinoma (EAC) and other solid tumors.

METHODS

An integrated genomics strategy was used to identify deoxyribonucleases correlating with genomic instability (as assessed from total copy number events in each patient) in 6 cancers. Apurinic/apyrimidinic nuclease 1 (APE1), identified as the top gene in functional screens, was either suppressed in cancer cell lines or overexpressed in normal esophageal cells and the impact on genome stability and growth was monitored in vitro and in vivo. The impact on DNA and chromosomal instability was monitored using multiple approaches, including investigation of micronuclei, acquisition of single nucleotide polymorphisms, whole genome sequencing, and/or multicolor fluorescence in situ hybridization.

RESULTS

Expression of 4 deoxyribonucleases correlated with genomic instability in 6 human cancers. Functional screens of these genes identified APE1 as the top candidate for further evaluation. APE1 suppression in EAC, breast, lung, and prostate cancer cell lines caused cell cycle arrest; impaired growth and increased cytotoxicity of cisplatin in all cell lines and types and in a mouse model of EAC; and inhibition of homologous recombination and spontaneous and chemotherapy-induced genomic instability. APE1 overexpression in normal cells caused a massive chromosomal instability, leading to their oncogenic transformation. Evaluation of these cells by means of whole genome sequencing demonstrated the acquisition of changes throughout the genome and identified homologous recombination as the top mutational process.

CONCLUSIONS

Elevated APE1 dysregulates homologous recombination and cell cycle, contributing to genomic instability, tumorigenesis, and chemoresistance, and its inhibitors have the potential to target these processes in EAC and possibly other cancers.

Biomarkers for the Detection and Risk Stratification of Aggressive Prostate Cancer

Current strategies for the clinical management of prostate cancer are inadequate for a precise risk stratification between indolent and aggressive tumors. Recently developed tissue-based molecular biomarkers have refined the risk assessment of the disease. The characterization of tissue biopsy components and subsequent identification of relevant tissue-based molecular alterations have the potential to improve the clinical decision making and patient outcomes. However, tissue biopsies are invasive and spatially restricted due to tumor heterogeneity. Therefore, there is an urgent need for complementary diagnostic and prognostic options. Liquid biopsy approaches are minimally invasive with potential utility for the early detection, risk stratification, and monitoring of tumors. In this review, we focus on tissue and liquid biopsy biomarkers for early diagnosis and risk stratification of prostate cancer, including modifications on the genomic, epigenomic, transcriptomic, and proteomic levels. High-risk molecular alterations combined with orthogonal clinical parameters can improve the identification of aggressive tumors and increase patient survival.

Long non-coding RNAs correlate with genomic stability in prostate cancer: A clinical outcome and survival analysis

BACKGROUND

Long non-coding RNAs (lncRNAs) participate in the regulation of genomic stability. Understanding their biological functions can help us identify the mechanisms of the occurrence and progression of cancers and can provide theoretical guidance and the basis for treatment.

RESULTS

Based on the mutation hypothesis, we proposed a computational framework to identify genomic instability-related lncRNAs. Based on the differentially-expressed lncRNAs (DElncRNAs), we constructed a genomic instability-derived lncRNA signature (GILncSig) to calculate and stratify outcomes in patients with prostate cancer. It is an independent predictor of overall survival. The area under the curve = 0.805. This value may be more significant than the classic prognostic markers TP53 and Speckle-type POZ protein (SPOP) in terms of outcome prediction.

CONCLUSIONS

In summary, we conducted a computation approach and resource for mining genome instability-related lncRNAs. It may turn out to be highly significant for genomic instability and customized decision-making for patients with prostate cancer. It also may lead to effective methods and resources to study the molecular mechanism of genomic instability-related lncRNAs.

PARP inhibition in prostate cancer

Defects in DNA damage repair genes are more common in prostate cancer than previously thought. These alterations provide an opportunity for precision oncology approaches and a number of studies have now shown that PARP inhibitors can have significant antitumor activity in men with DNA damage repair-deficient metastatic castration-resistant prostate cancer. This review summarizes the key clinical trials related to the use of PARP inhibitors in prostate cancer. Besides clinical outcomes, toxicity, and PARP inhibitor resistance, the role of different DNA repair genes in the response to PARP inhibition will be discussed.

Modeling human prostate cancer progression in vitro

Detailed mechanisms involved in prostate cancer (CaP) development and progression are not well understood. Current experimental models used to study CaP are not well suited to address this issue. Previously, we have described the hormonal progression of non-tumorigenic human prostate epithelial cells (BPH1) into malignant cells via tissue recombination. Here, we describe a method to derive human cell lines from distinct stages of CaP that parallel cellular, genetic and epigenetic changes found in patients with cancers. This BPH1-derived Cancer Progression (BCaP) model represents different stages of cancer. Using diverse analytical strategies, we show that the BCaP model reproduces molecular characteristics of CaP in human patients. Furthermore, we demonstrate that BCaP cells have altered gene expression of shared pathways with human and transgenic mouse CaP data, as well as, increasing genomic instability with TMPRSS2-ERG fusion in advanced tumor cells. Together, these cell lines represent a unique model of human CaP progression providing a novel tool that will allow the discovery and experimental validation of mechanisms regulating human CaP development and progression. This BPH1-derived Cancer Progression (BCaP) model represents different stages of cancer. The BCaP model reproduces molecular characteristics of prostate cancer. The cells have altered gene expression with TMPRSS2-ERG fusion representing a unique model for prostate cancer progression.

Chromosomal instability in untreated primary prostate cancer as an indicator of metastatic potential

Background

Metastatic prostate cancer (PC) is highly lethal. The ability to identify primary tumors capable of dissemination is an unmet need in the quest to understand lethal biology and improve patient outcomes. Previous studies have linked chromosomal instability (CIN), which generates aneuploidy following chromosomal missegregation during mitosis, to PC progression. Evidence of CIN includes broad copy number alterations (CNAs) spanning > 300 base pairs of DNA, which may also be measured via RNA expression signatures associated with CNA frequency. Signatures of CIN in metastatic PC, however, have not been interrogated or well defined. We examined a published 70-gene CIN signature (CIN70) in untreated and castration-resistant prostate cancer (CRPC) cohorts from The Cancer Genome Atlas (TCGA) and previously published reports. We also performed transcriptome and CNA analysis in a unique cohort of untreated primary tumors collected from diagnostic prostate needle biopsies (PNBX) of localized (M0) and metastatic (M1) cases to determine if CIN was linked to clinical stage and outcome.

Methods

PNBX were collected from 99 patients treated in the VA Greater Los Angeles (GLA-VA) Healthcare System between 2000 and 2016. Total RNA was extracted from high-grade cancer areas in PNBX cores, followed by RNA sequencing and/or copy number analysis using OncoScan. Multivariate logistic regression analyses permitted calculation of odds ratios for CIN status (high versus low) in an expanded GLA-VA PNBX cohort (n = 121).

Results

The CIN70 signature was significantly enriched in primary tumors and CRPC metastases from M1 PC cases. An intersection of gene signatures comprised of differentially expressed genes (DEGs) generated through comparison of M1 versus M0 PNBX and primary CRPC tumors versus metastases revealed a 157-gene “metastasis” signature that was further distilled to 7-genes (PC-CIN) regulating centrosomes, chromosomal segregation, and mitotic spindle assembly. High PC-CIN scores correlated with CRPC, PC-death and all-cause mortality in the expanded GLA-VA PNBX cohort. Interestingly, approximately 1/3 of M1 PNBX cases exhibited low CIN, illuminating differential pathways of lethal PC progression.

Conclusions

Measuring CIN in PNBX by transcriptome profiling is feasible, and the PC-CIN signature may identify patients with a high risk of lethal progression at the time of diagnosis.

High prevalence of DNA damage repair gene defects and TP53 alterations in men with treatment-naïve metastatic prostate cancer -Results from a prospective pilot study using a 37 gene panel

BACKGROUND

Defects in DNA damage repair genes characterize a subset of men with prostate cancer and provide an attractive opportunity for precision oncology approaches. The prevalence of such perturbations in newly diagnosed, treatment-naïve patients with a high risk for lethal disease outcome, however, has not been sufficiently explored.

PATIENTS AND METHODS

Prostate cancer specimens from 67 men with newly diagnosed early onset, localized high-risk/locally advanced or metastatic prostate cancer were included in this prospective pilot study. Tumor samples, including 30 prostate biopsies, were analyzed by targeted next generation sequencing using a formalin-fixed, paraffin-embedded tissue-optimized 37 DNA damage repair and checkpoint gene panel.

RESULTS

The drop-out rate due to an insufficient quantity of DNA was 4.5% (3 of 67 patients). In the remaining 64 patients, the rate of pathogenic DNA damage repair gene mutations was 26.6%. The highest rate of pathogenic DNA damage repair and checkpoint gene mutations was found in men with treatment-naïve metastatic prostate cancer (38.9%). In addition, a high number of likely pathogenic mutations and gene deletions were detected. Altogether, one or more pathogenic mutation, likely pathogenic mutation or gene deletion affected 43 of 64 patients (67.2%) including 29 of 36 patients (80.6%) with treatment-naïve metastatic prostate cancer. Men with metastatic prostate cancer showed a high prevalence of alterations in TP53 (36.1%).

CONCLUSIONS

This pilot study demonstrates the feasibility, performance and clinical relevance of somatic targeted next generation sequencing using a unique 37 DNA damage repair and checkpoint gene panel under routine conditions. Our results indicate that this approach can detect actionable DNA repair gene alterations, uncommon mutations as well as mutations associated with therapy resistance in a high number of patients, in particular patients with treatment-naïve metastatic prostate cancer.

Significance of BRCA2 and RB1 Co-loss in Aggressive Prostate Cancer Progression

PURPOSE

Previous sequencing studies revealed that alterations of genes associated with DNA damage response (DDR) are enriched in men with metastatic castration-resistant prostate cancer (mCRPC). BRCA2, a DDR and cancer susceptibility gene, is frequently deleted (homozygous and heterozygous) in men with aggressive prostate cancer. Here we show that patients with prostate cancer who have lost a copy of BRCA2 frequently lose a copy of tumor suppressor gene RB1; importantly, for the first time, we demonstrate that co-loss of both genes in early prostate cancer is sufficient to induce a distinct biology that is likely associated with worse prognosis.

EXPERIMENTAL DESIGN

We prospectively investigated underlying molecular mechanisms and genomic consequences of co-loss of BRCA2 and RB1 in prostate cancer. We used CRISPR-Cas9 and RNAi-based methods to eliminate these two genes in prostate cancer cell lines and subjected them to in vitro studies and transcriptomic analyses. We developed a 3-color FISH assay to detect genomic deletions of BRCA2 and RB1 in prostate cancer cells and patient-derived mCRPC organoids.

RESULTS

In human prostate cancer cell lines (LNCaP and LAPC4), loss of BRCA2 leads to the castration-resistant phenotype. Co-loss of BRCA2-RB1 in human prostate cancer cells induces an epithelial-to-mesenchymal transition, which is associated with invasiveness and a more aggressive disease phenotype. Importantly, PARP inhibitors attenuate cell growth in human mCRPC-derived organoids and human CRPC cells harboring single-copy loss of both genes.

CONCLUSIONS

Our findings suggest that early identification of this aggressive form of prostate cancer offers potential for improved outcomes with early introduction of PARP inhibitor-based therapy.See related commentary by Mandigo and Knudsen, p. 1784.

Translocations involving ETS family proteins in human cancer

The ETS transcription factors regulate expression of genes involved in normal cell development, proliferation, differentiation, angiogenesis, and apoptosis, consisting of 28 family members in humans. Dysregulation of these transcription factors facilitates cell proliferation in cancers, and several members participate in invasion and metastasis by activating certain gene transcriptions. ETS1 and ETS2 are the founding members of the ETS family and regulate transcription by binding to ETS sequences. Three chimeric genes involving ETS genes have been identified in human cancers, which are EWS-FLI1 in Ewing's sarcoma, TMPRSS2-ERG in prostate cancer, and ETV6-RUNX1 in acute lymphocytic leukemia. Although these fusion transcripts definitely contribute to the pathogenesis of the disease, the impact of these fusion transcripts on patients' prognosis is highly controversial. In the present review, the roles of ETS protein translocations in human carcinogenesis are discussed.

FGF-2 is a driving force for chromosomal instability and a stromal factor associated with adverse clinico-pathological features in prostate cancer

BACKGROUND

There is mounting evidence to suggest that stromal cells play an integral role in the progression of prostate cancer (PCa). One of the most frequently altered growth factors in PCa is fibroblast growth factor-2 (FGF-2). It has previously been proposed that early stages of PCa are characterized by a primarily exogenous, that is, stromal cell-derived FGF-2 production, whereas advanced tumors rely more on an autocrine FGF-2 production. Prostate cancer progression is characterized by an increase of genomic instability including aneuploidy and structural chromosomal alterations. Herein, we address 2 problems that have not been comprehensively answered. First, we ask whether exogenous FGF-2 can directly drive genomic instability to promote PCa progression. Second, we investigate whether and to what extent stromal FGF-2 expression is maintained in advanced PCa and whether this influences tumor progression and patient prognosis.

METHODS

In vitro experiments to investigate the role of FGF-2 in numerical and structural chromosomal instability were performed using immunofluorescence microscopy, fluorescence in situ hybridization and single cell electrophoresis. A human patient-derived xenograft mouse model recapitulating osteoblastic PCa bone metastasis was used for in vivo validation experiments. The prognostic role of stromal FGF-2 expression was analyzed using immunohistochemical staining of a tissue microarray with primary tumor specimens from 162 predominantly high-risk patients with PCa.

RESULTS

Our results show that FGF-2 not only rapidly induces mitotic defects and numerical chromosomal imbalances but also an enhanced DNA breakage to promote chromosomal instability. Using the patient-derived xenograft model, we show that a deregulation of the FGF axis results in an increase of mitotic aberrations as well as DNA damage checkpoint activation in vivo. The FGFR inhibitor dovitinib was found to reduce numerical chromosomal instability as well as DNA breakage, thus underscoring the relevance of the FGF axis in promoting genomic instability. An overexpression of tumor cell-associated FGF-2 was detected in 52 of 162 patients (32.1%), whereas a stromal overexpression was found in 27 of 165 patients (16%). Remarkably, a strong stromal FGF-2 expression was associated with a significantly higher clinical stage and higher biochemical recurrence rate. Patients with strong stromal FGF-2 expression also had a significantly worse biochemical recurrence-free survival.

CONCLUSIONS

Our results underscore that exogenous FGF-2 can shape PCa cell genomes and that stromal FGF-2 expression is detectable in a sizeable proportion of advanced PCa where it is associated with adverse clinico-pathological features. Our results highlight the impact of the tumor stroma on malignant progression and provide a rationale for a further exploration of components of the tumor stroma as therapeutic targets in PCa.

Chromothripsis in acute myeloid leukemia: biological features and impact on survival

Chromothripsis is a one-step genome-shattering catastrophe resulting from disruption of one or few chromosomes in multiple fragments and consequent random rejoining and repair. This study defines incidence of chromothripsis in 395 newly diagnosed adult acute myeloid leukemia (AML) patients from three institutions, its impact on survival and its genomic background. SNP 6.0 or CytoscanHD Array (Affymetrix^®) were performed on all samples. We detected chromothripsis with a custom algorithm in 26/395 patients. Patients harboring chromothripsis had higher age (p = 0.002), ELN high risk (HR) (p < 0.001), lower white blood cell (WBC) count (p = 0.040), TP53 loss, and/or mutations (p < 0.001) while FLT3 (p = 0.025), and NPM1 (p = 0.032) mutations were mutually exclusive with chromothripsis. Chromothripsis-positive patients showed a worse overall survival (OS) (p < 0.001) compared with HR patients (p = 0.011) and a poor prognosis in a COX-HR optimal regression model. Chromothripsis presented the hallmarks of chromosome instability [i.e., TP53 alteration, 5q deletion, higher mean of copy number alteration (CNA), complex karyotype, alterations in DNA repair, and cell cycle] and focal deletions on chromosomes 4, 7, 12, 16, and 17. CBA. FISH showed that chromothripsis is associated with marker, derivative, and ring chromosomes. In conclusion, chromothripsis frequently occurs in AML (6.6%) and influences patient prognosis and disease biology.

Presence of TMPRSS2-ERG is associated with alterations of the metabolic profile in human prostate cancer

TMPRSS2-ERG has been proposed to be a prognostic marker for prostate cancer. The aim of this study was to identify changes in metabolism, genes and biochemical recurrence related to TMPRSS2-ERG by using an integrated approach, combining metabolomics, transcriptomics, histopathology and clinical data in a cohort of 129 human prostate samples (41 patients). Metabolic analyses revealed lower concentrations of citrate and spermine comparing ERG_high to ERG_low samples, suggesting an increased cancer aggressiveness of ERG_high compared to ERG_low. These results could be validated in a separate cohort, consisting of 40 samples (40 patients), and magnetic resonance spectroscopy imaging (MRSI) indicated an in vivo translational potential. Alterations of gene expression levels associated with key enzymes in the metabolism of citrate and polyamines were in consistence with the metabolic results. Furthermore, the metabolic alterations between ERG_high and ERG_low were more pronounced in low Gleason samples than in high Gleason samples, suggesting it as a potential tool for risk stratification. However, no significant difference in biochemical recurrence was detected, although a trend towards significance was detected for low Gleason samples. Using an integrated approach, this study suggests TMPRSS2-ERG as a potential risk stratification tool for inclusion of active surveillance patients.

High inducible nitric oxide synthase in prostate tumor epithelium is associated with lethal prostate cancer

OBJECTIVE

The aim of this study was to investigate the role of inducible nitric oxide synthase (iNOS) in lethal prostate cancer (PCa) by studying the iNOS immunoreactivity in tumor tissue from men diagnosed with localized PCa.

MATERIALS AND METHODS

This study is nested within a cohort of men diagnosed with incidental PCa undergoing transurethral resection of the prostate (the Swedish Watchful Waiting Cohort). To investigate molecular determinants of lethal PCa, men who died from PCa (n = 132) were selected as cases; controls (n = 168) comprised men with PCa who survived for at least 10 years without dying from PCa during follow-up. The immunoreactivity of iNOS in prostate tumor epithelial cells and in cells of the surrounding stroma was scored as low/negative, moderate or high. Logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (95% CIs) for lethal PCa according to iNOS category.

RESULTS

There was no association between iNOS immunoreactivity in stroma and lethal disease. However, when comparing high versus low/negative iNOS immunoreactivity in epithelial cells, the OR for lethal PCa was 3.80 (95% CI 1.45-9.97).

CONCLUSION

Patients with localized PCa have variable outcomes, especially those with moderately differentiated tumors. Identifying factors associated with long-term PCa outcomes can elucidate PCa tumor biology and identify new candidate prognostic markers. These findings support the hypothesis that high iNOS in tumor epithelium of the prostate is associated with lethal disease.

Distinct subtypes of genomic PTEN deletion size influence the landscape of aneuploidy and outcome in prostate cancer

Background

Inactivation of the PTEN tumor suppressor gene by deletion occurs in 20-30% of prostate cancer tumors and loss strongly correlates with a worse outcome. PTEN loss of function not only leads to activation of the PI3K/AKT pathway, but is also thought to affect genome stability and increase levels of tumor aneuploidy. We performed an in silico integrative genomic and transcriptomic analysis of 491 TCGA prostate cancer tumors. These data were used to map the genomic sizes of PTEN gene deletions and to characterize levels of instability and patterns of aneuploidy acquisition.

Results

PTEN homozygous deletions had a significant increase in aneuploidy compared to PTEN tumors without an apparent deletion, and hemizygous deletions showed an intermediate aneuploidy profile. A supervised clustering of somatic copy number alterations (SCNA) demonstrated that the size of PTEN deletions was not random, but comprised five distinct subtypes: (1) "Small Interstitial" (70 bp-789Kb); (2) "Large Interstitial" (1-7 MB); (3) "Large Proximal" (3-65 MB); (4) "Large Terminal" (8-64 MB), and (5) "Extensive" (71-132 MB). Many of the deleted fragments in each subtype were flanked by low copy repetitive (LCR) sequences. SCNAs such as gain at 3q21.1-3q29 and deletions at 8p, RB1, TP53 and TMPRSS2-ERG were variably present in all subtypes. Other SCNAs appeared to be recurrent in some deletion subtypes, but absent from others. To determine how the aneuploidy influenced global levels of gene expression, we performed a comparative transcriptome analysis. One deletion subtype (Large Interstitial) was characterized by gene expression changes associated with angiogenesis and cell adhesion, structure, and metabolism. Logistic regression demonstrated that this deletion subtype was associated with a high Gleason score (HR = 2.386; 95% C.I. 1.245-4.572), extraprostatic extension (HR = 2.423, 95% C.I. 1.157-5.075), and metastasis (HR = 7.135; 95% C.I. 1.540-33.044). Univariate and multivariate Cox Regression showed that presence of this deletion subtype was also strongly predictive of disease recurrence.

Conclusions

Our findings indicate that genomic deletions of PTEN fall into five different size distributions, with breakpoints that often occur close LCR regions, and that each subtype is associated with a characteristic aneuploidy signature. The Large Interstitial deletion had a distinct gene expression signature that was related to cancer progression and was also predictive of a worse prognosis.

Targeting DNA Damage Response in Prostate Cancer by Inhibiting Androgen Receptor-CDC6-ATR-Chk1 Signaling

Cell division cycle 6 (CDC6), an androgen receptor (AR) target gene, is implicated in regulating DNA replication and checkpoint mechanisms. CDC6 expression is increased during prostate cancer (PCa) progression and positively correlates with AR in PCa tissues. AR or CDC6 knockdown, together with AZD7762, a Chk1/2 inhibitor, results in decreased TopBP1-ATR-Chk1 signaling and markedly increased ataxia-telangiectasia-mutated (ATM) phosphorylation, a biomarker of DNA damage, and synergistically increases treatment efficacy. Combination treatment with the AR signaling inhibitor enzalutamide (ENZ) and the Chk1/2 inhibitor AZD7762 demonstrates synergy with regard to inhibition of AR-CDC6-ATR-Chk1 signaling, ATM phosphorylation induction, and apoptosis in VCaP (mutant p53) and LNCaP-C4-2b (wild-type p53) cells. CDC6 overexpression significantly reduced ENZ- and AZD7762-induced apoptosis. Additive or synergistic therapeutic activities are demonstrated in AR-positive animal xenograft models. These findings have important clinical implications, since they introduce a therapeutic strategy for AR-positive, metastatic, castration-resistant PCa, regardless of p53 status, through targeting AR-CDC6-ATR-Chk1 signaling.

Challenges for Super-Resolution Localization Microscopy and Biomolecular Fluorescent Nano-Probing in Cancer Research

Understanding molecular interactions and regulatory mechanisms in tumor initiation, progression, and treatment response are key requirements towards advanced cancer diagnosis and novel treatment procedures in personalized medicine. Beyond decoding the gene expression, malfunctioning and cancer-related epigenetic pathways, investigations of the spatial receptor arrangements in membranes and genome organization in cell nuclei, on the nano-scale, contribute to elucidating complex molecular mechanisms in cells and tissues. By these means, the correlation between cell function and spatial organization of molecules or molecular complexes can be studied, with respect to carcinogenesis, tumor sensitivity or tumor resistance to anticancer therapies, like radiation or antibody treatment. Here, we present several new applications for bio-molecular nano-probes and super-resolution, laser fluorescence localization microscopy and their potential in life sciences, especially in biomedical and cancer research. By means of a tool-box of fluorescent antibodies, green fluorescent protein (GFP) tagging, or specific oligonucleotides, we present tumor relevant re-arrangements of Erb-receptors in membranes, spatial organization of Smad specific ubiquitin protein ligase 2 (Smurf2) in the cytosol, tumor cell characteristic heterochromatin organization, and molecular re-arrangements induced by radiation or antibody treatment. The main purpose of this article is to demonstrate how nano-scaled distance measurements between bio-molecules, tagged by appropriate nano-probes, can be applied to elucidate structures and conformations of molecular complexes which are characteristic of tumorigenesis and treatment responses. These applications open new avenues towards a better interpretation of the spatial organization and treatment responses of functionally relevant molecules, at the single cell level, in normal and cancer cells, offering new potentials for individualized medicine.

Influence of chronic inflammation on Bcl-2 and PCNA expression in prostate needle biopsy specimens

The association between inflammation and cancer has been established in certain forms of human malignancies; however, its role in prostate cancer remains unclear. The present study investigates a possible association between chronic inflammation and the development of epithelial neoplasia in the prostate. Needle biopsy specimens were obtained from patients with serum prostate-specific antigen levels >4 ng/ml, evaluated for morphological findings, and immunostained for Bcl-2 and proliferating cell nuclear antigen (PCNA). Bcl-2 is a survival protein that appears to lie at a nodal point in pathways involved in cell survival, carcinogenesis, and development of therapeutic resistance in certain cancer types. Similarly, PCNA is a critical protein for DNA replication, repair of DNA damage, chromatin structure maintenance, chromosome segregation and cell-cycle progression. The association between these two proteins was examined in prostate tissues with and without chronic inflammation, as well as tissues with and without evidence of neoplastic changes. Of the 106 needle biopsies examined, 18% exhibited atrophy with inflammation. Proliferative inflammatory atrophy/post-atrophic hyperplasia were observed in 42%, high-grade prostatic intraepithelial neoplasia (HGPIN) in 8%, prostatic adenocarcinoma in 11%, and 2% had atypical acinar proliferation suspicious for malignancy. A total of 36 specimens were stained for Bcl-2 and PCNA. Bcl-2 was expressed widely in inflammatory and epithelial tissue; however, more intense expression was observed in the areas of chronic inflammation, predominantly in infiltrating immune cells. The highest proliferation index was observed in the epithelia of HGPIN and cancer. An inverse correlation between the expression of Bcl-2 and the expression of PCNA was observed in the epithelium. The areas of chronic inflammation were associated with increased Bcl-2 expression, whereas the highly proliferative epithelium minimally expressed Bcl-2. These results suggest that Bcl-2 alters the phenotype of particular epithelial cells with a gain in neoplastic characteristics, leading to a likely precursor that may later progress into HGPIN and cancer.

Overexpression of Cdc20 in clinically localized prostate cancer: Relation to high Gleason score and biochemical recurrence after laparoscopic radical prostatectomy

OBJECTIVES

This study was aimed to explore Cdc20 expression and its correlation with clinicopathological characteristics and biochemical recurrence (BCR) after laparoscopic radical prostatectomy (LRP) in clinically localized prostate cancer (PCa).

METHODS

Cdc20 expression was examined by immunohistochemistry in 166 cases, including 60 cases of benign hyperplasia of prostate (BPH) patients treated by transurethral resection and 106 cases of consecutive PCa patients treated by LRP without neoadjuvant therapy in a single Chinese institution. The correlation with clinicopathological features and the predictive value for BCR were statistically analyzed.

RESULTS

Cdc20 expression was detected in 52 (86.7%) BPH and 97 (91.5%) PCa samples, which was statistically insignificant (P= 0.675). The rate of patients with high expression of Cdc20 was 21.7% in BPH and 37.7% in PCa (P= 0.033). A correlation was revealed between Cdc20 expression and postoperative Gleason scores (P= 0.046), positive surgical margin (P< 0.001). BCR-free survival was significantly lower in patients with high Cdc20 expression than those with low Cdc20 expression (P= 0.018). Univariate analysis indicated pTstage, post operative Gleason score, seminal vesicle invasion, lymph node invasion, surgical margin and Cdc20 expression significantly influenced BCR. Multivariate analysis revealed that postoperative Gleason score, seminal vesicle invasion, lymph node invasion, surgical margin and Cdc20 expression were independent predictors for BCR. After stratified by Gleason score and surgical margin status, Cdc20 expression and lymph node invasion remained significant in Cox regression analysis.

CONCLUSIONS

Overexpression of Cdc20 may serve as an independent predictor for BCR in patients of clinically localized PCa undergoing LRP without neoadjuvant therapy.

Prognostic Significance and Functional Role of CEP57 in Prostate Cancer

We have recently shown that centrosomal protein 57 (CEP57) is overexpressed in a subset of human prostate cancers. CEP57 is involved in intracellular transport processes, and its overexpression causes mitotic defects as well as abnormal microtubule nucleation and bundling. In the present study, we further characterized the prognostic and functional role of CEP57 in prostate cancer. Unexpectedly, we found that high CEP57 expression is an independent prognostic factor for a more favorable biochemical recurrence-free survival in two large patient cohorts. To reconcile this finding with the ability of CEP57 to cause cell division errors and thus potentially promote malignant progression, we hypothesized that alterations of microtubule-associated transport processes, in particular nuclear translocation of the androgen receptor (AR), may play a role in our finding. However, CEP57 overexpression and microtubule bundling had, surprisingly, no effect on the nuclear translocation of the AR. Instead, we found a significant increase of cells with disarranged microtubules and a cellular morphology suggestive of a cytokinesis defect. Because mitotic dysfunction leads to a reduced daughter cell formation, it can explain the survival benefit of patients with increased CEP57 expression. In contrast, we show that a reduced expression of CEP57 is associated with malignant growth and metastasis. Taken together, our findings underscore that high CEP57 expression is associated with mitotic impairment and less aggressive tumor behavior. Because the CEP57-induced microtubule stabilization had no detectable effect on AR nuclear translocation, our results furthermore suggest that microtubule-targeting therapeutics used in advanced prostate cancer such as docetaxel may have modes of action that are at least in part independent of AR transport inhibition.

Widespread telomere instability in prostatic lesions

A critical function of the telomere is to disguise chromosome ends from cellular recognition as double strand breaks, thereby preventing aberrant chromosome fusion events. Such chromosome end-to-end fusions are known to initiate genomic instability via breakage-fusion-bridge cycles. Telomere dysfunction and other forms of genomic assault likely result in misregulation of genes involved in growth control, cell death, and senescence pathways, lowering the threshold to malignancy and likely drive disease progression. Shortened telomeres and anaphase bridges have been reported in a wide variety of early precursor and malignant cancer lesions including those of the prostate. These findings are being extended using methods for the analysis of telomere fusions (decisive genetic markers for telomere dysfunction) specifically within human tissue DNA. Here we report that benign prostatic hyperplasia (BPH), high-grade prostatic intraepithelial neoplasia (PIN), and prostate cancer (PCa) prostate lesions all contain similarly high frequencies of telomere fusions and anaphase bridges. Tumor-adjacent, histologically normal prostate tissue generally did not contain telomere fusions or anaphase bridges as compared to matched PCa tissues. However, we found relatively high levels of telomerase activity in this histologically normal tumor-adjacent tissue that was reduced but closely correlated with telomerase levels in corresponding PCa samples. Thus, we present evidence of high levels of telomere dysfunction in BPH, an established early precursor (PIN) and prostate cancer lesions but not generally in tumor adjacent normal tissue. Our results suggest that telomere dysfunction may be a common gateway event leading to genomic instability in prostate tumorigenesis. .

Changes in Susceptibility to Oncolytic Vesicular Stomatitis Virus during Progression of Prostate Cancer

A major challenge to oncolytic virus therapy is that individual cancers vary in their sensitivity to oncolytic viruses, even when these cancers arise from the same tissue type. Variability in response may arise due to differences in the initial genetic lesions leading to cancer development. Alternatively, susceptibility to viral oncolysis may change during cancer progression. These hypotheses were tested using cells from a transgenic mouse model of prostate cancer infected with vesicular stomatitis virus (VSV). Primary cultures from murine cancers derived from prostate-specific Pten deletion contained a mixture of cells that were susceptible and resistant to VSV. Castration-resistant cancers contained a higher percentage of susceptible cells than cancers from noncastrated mice. These results indicate both susceptible and resistant cells can evolve within the same tumor. The role of Pten deletion was further investigated using clonal populations of murine prostate epithelial (MPE) progenitor cells and tumor-derived Pten(-/-) cells. Deletion of Pten in MPE progenitor cells using a lentivirus vector resulted in cells that responded poorly to interferon and were susceptible to VSV infection. In contrast, tumor-derived Pten(-/-) cells expressed higher levels of the antiviral transcription factor STAT1, activated STAT1 in response to VSV, and were resistant to VSV infection. These results suggest that early in tumor development following Pten deletion, cells are primarily sensitive to VSV, but subsequent evolution in tumors leads to development of cells that are resistant to VSV infection. Further evolution in castration-resistant tumors leads to tumors in which cells are primarily sensitive to VSV.

IMPORTANCE

There has been a great deal of progress in the development of replication-competent viruses that kill cancer cells (oncolytic viruses). However, a major problem is that individual cancers vary in their sensitivity to oncolytic viruses, even when these cancers arise from the same tissue type. The experiments presented here were to determine whether both sensitive and resistant cells are present in prostate cancers originating from a single genetic lesion in transgenic mice, prostate-specific deletion of the gene for the tumor suppressor Pten. The results indicate that murine prostate cancers are composed of both cells that are sensitive and cells that are resistant to oncolytic vesicular stomatitis virus (VSV). Furthermore, androgen deprivation led to castration-resistant prostate cancers that were composed primarily of cells that were sensitive to VSV. These results are encouraging for the use of VSV for the treatment of prostate cancers that are resistant to androgen deprivation therapy.