Telomere attrition in isolated high-grade prostatic intraepithelial neoplasia and surrounding stroma is predictive of prostate cancer

Understanding and targeting prostate cancer cell heterogeneity and plasticity

Prostate cancer (PCa) is a prevalent malignancy that occurs primarily in old males. Prostate tumors in different patients manifest significant inter-patient heterogeneity with respect to histo-morphological presentations and molecular architecture. An individual patient tumor also harbors genetically distinct clones in which PCa cells display intra-tumor heterogeneity in molecular features and phenotypic marker expression. This inherent PCa cell heterogeneity, e.g., in the expression of androgen receptor (AR), constitutes a barrier to the long-term therapeutic efficacy of AR-targeting therapies. Furthermore, tumor progression as well as therapeutic treatments induce PCa cell plasticity such that AR-positive PCa cells may turn into AR-negative cells and prostate tumors may switch lineage identity from adenocarcinomas to neuroendocrine-like tumors. This induced PCa cell plasticity similarly confers resistance to AR-targeting and other therapies. In this review, I first discuss PCa from the perspective of an abnormal organ development and deregulated cellular differentiation, and discuss the luminal progenitor cells as the likely cells of origin for PCa. I then focus on intrinsic PCa cell heterogeneity in treatment-naïve tumors with the presence of prostate cancer stem cells (PCSCs). I further elaborate on PCa cell plasticity induced by genetic alterations and therapeutic interventions, and present potential strategies to therapeutically tackle PCa cell heterogeneity and plasticity. My discussions will make it clear that, to achieve enduring clinical efficacy, both intrinsic PCa cell heterogeneity and induced PCa cell plasticity need to be targeted with novel combinatorial approaches.

Race Differences in Telomere Length in Benign Prostate Biopsies and Subsequent Risk of Prostate Cancer

BACKGROUND

Telomere shortening is linked to aging and may be associated with increased risk for cancer. Most cancer studies have used telomere length in leukocytes rather than in the target tissue of cancer origin.

METHODS

A case-control study of 524 case-control pairs with a benign prostate biopsy nested within a historical cohort of 10,478 men was conducted to determine whether premalignant prostate telomere length (assessed using a modified qRT-PCR) is associated with prostate cancer risk.

RESULTS

Telomere lengths in benign prostate biopsies of cases versus controls were similar (1.46 ± 0.38 vs. 1.45 ± 0.42; P = 0.49). African American (AA) men had significantly shorter telomeres compared with White men (1.51 ± 0.38 vs. 1.63 ± 0.39; P < 0.0001). In race-stratified analyses, increasing telomere length was more strongly associated with prostate cancer risk in White men, wherein those with telomere length in the highest quartile had 1.9-fold greater adjusted risk of prostate cancer compared with men with prostate telomere lengths in the lowest quartile [OR = 1.90; 95% confidence interval (CI) = 1.08-3.36]. Men in the highest telomere length quartile also had a greater risk of aggressive prostate cancer compared with men with telomere lengths in the lowest quartile (OR = 2.78; 95% CI = 1.25-6.19).

CONCLUSIONS

White men have longer telomeres in benign prostate tissue compared with AA men, and those with the longest telomeres may be at increased risk for prostate cancer, particularly the more aggressive form of the disease.

IMPACT

Race-specific telomere length measures may be an early biomarker of aggressive prostate cancer.

Telomere DNA Damage Signaling Regulates Prostate Cancer Tumorigenesis

Telomere shortening has been demonstrated in benign prostatic hypertrophy (BPH), which is associated with prostate epithelial cell senescence. Telomere shortening is the most frequently observed genetic alteration in prostatic intraepithelial neoplasia, and is associated with poor clinical outcomes in prostate cancer. Gene expression database analysis revealed decreased TRF2 expression during malignant progression of the prostate gland. We reasoned that reduced TRF2 expression in prostate epithelium, by activating the telomere DNA damage response, would allow us to model both benign and malignant prostate disease. Prostate glands with reduced epithelial TRF2 expression developed age- and p53-dependent hypertrophy, senescence, ductal dilation, and smooth muscle hyperplasia similar to human BPH. Prostate tumors with reduced TRF2 expression were classified as high-grade androgen receptor-negative adenocarcinomas, which exhibited decreased latency, increased proliferation, and distant metastases. Prostate cancer stem cells with reduced TRF2 expression were highly tumorigenic and maintained telomeres both by telomerase and alternative lengthening (ALT). Telomerase inhibition in prostate glands with reduced TRF2 expression produced significant reduction in prostate tumor incidence by halting progression at intraepithelial neoplasia (PIN). These lesions were highly differentiated, exhibited low proliferation index, and high apoptotic cell fraction. Prostate tumors with reduced TRF2 expression and telomerase inhibition failed to metastasize and did not exhibit ALT. IMPLICATIONS: Our results demonstrate that the telomere DNA damage response regulates BPH, PIN, and prostate cancer and may be therapeutically manipulated to prevent prostate cancer progression.

Underlying Causes and Therapeutic Targeting of the Inflammatory Tumor Microenvironment

Historically, the link between chronic inflammation and cancer has long been speculated. Only more recently, pre-clinical and epidemiologic data as well as clinical evidence all point to the role of the tumor microenvironment as inextricably connected to the neoplastic process. The tumor microenvironment (TME), a complex mix of vasculature, inflammatory cells, and stromal cells is the essential "soil" helping to modulate tumor potential. Increasingly, evidence suggests that chronic inflammation modifies the tumor microenvironment, via a host of mechanisms, including the production of cytokines, pro-inflammatory mediators, angiogenesis, and tissue remodeling. Inflammation can be triggered by a variety of different pressures, such as carcinogen exposure, immune dysfunction, dietary habits, and obesity, as well as genetic alterations leading to oncogene activation or loss of tumor suppressors. In this review, we examine the concept of the tumor microenvironment as related to both extrinsic and intrinsic stimuli that promote chronic inflammation and in turn tumorigenesis. Understanding the common pathways inherent in an inflammatory response and the tumor microenvironment may shed light on new therapies for both primary and metastatic disease. The concept of personalized medicine has pushed the field of oncology to drill down on the genetic changes of a cancer, in the hopes of identifying individually targeted agents. Given the complexities of the tumor microenvironment, it is clear that effective oncologic therapies will necessitate targeting not only the cancer cells, but their dynamic relationship to the tumor microenvironment as well.

Quantification of telomere features in tumor tissue sections by an automated 3D imaging-based workflow

The microscopic analysis of telomere features provides a wealth of information on the mechanism by which tumor cells maintain their unlimited proliferative potential. Accordingly, the analysis of telomeres in tissue sections of patient tumor samples can be exploited to obtain diagnostic information and to define tumor subgroups. In many instances, however, analysis of the image data is conducted by manual inspection of 2D images at relatively low resolution for only a small part of the sample. As the telomere feature signal distribution is frequently heterogeneous, this approach is prone to a biased selection of the information present in the image and lacks subcellular details. Here we address these issues by using an automated high-resolution imaging and analysis workflow that quantifies individual telomere features on tissue sections for a large number of cells. The approach is particularly suited to assess telomere heterogeneity and low abundant cellular subpopulations with distinct telomere characteristics in a reproducible manner. It comprises the integration of multi-color fluorescence in situ hybridization, immunofluorescence and DNA staining with targeted automated 3D fluorescence microscopy and image analysis. We apply our method to telomeres in glioblastoma and prostate cancer samples, and describe how the imaging data can be used to derive statistically reliable information on telomere length distribution or colocalization with PML nuclear bodies. We anticipate that relating this approach to clinical outcome data will prove to be valuable for pretherapeutic patient stratification.

Genomic, pathological, and clinical heterogeneity as drivers of personalized medicine in prostate cancer

Prostate cancer (CaP) is the most commonly diagnosed malignancy in men in the Western world. In North America, more than 275,000 men are diagnosed annually, whereby approximately 1 in 6 men will be diagnosed with CaP in their lifetime, and 1 in 34 men will die from castration-resistant metastatic disease. Unfortunately, current clinical prognostic factors explain only a proportion of the observed variation in clinical outcome from patient to patient. Furthermore, overtreatment of indolent and low-risk cancers leads to inappropriate morbidity following radiotherapy or surgery. As such, better predictors of individualized prognosis and treatment response are urgently needed to triage patients to customized and intensified CaP treatment. Recent developments in next-generation sequencing have made it possible to identify prognostic and predictive signatures based on genomic profiles. We discuss the genetic basis of CaP progression from localized to systemic disease (e.g., point mutations, copy-number alterations, and structural variants) in relation with unique features of CaP biology, including intraprostatic and interprostatic heterogeneity, multifocality and multiclonality, TMPRSS2:ERG, and other ETS-family gene fusions. Finally, we focus on the use of genomic markers as prognostic factors for local failure and for systemic disease, as novel risk-stratification tools, in triaging patients to existing treatment options, and ultimately the potential of genomics for the identification of molecular targets for therapy of CaP.

Telomere length in peripheral blood leukocytes is associated with risk of colorectal cancer in Chinese population

Background

Human telomeres, tandem repeats of TTAGGG nucleotides at the ends of chromosomes, are essential for maintaining genomic integrity and stability. Results of previous epidemiologic studies about the association of telomere length with risk of colorectal cancer (CRC) have been conflicting.

Methods

A case-control study was conducted in a Han population in Wuhan, central China. The relative telomere length (RTL) was measured in peripheral blood leukocytes (PBLs) using quantitative real-time polymerase chain reaction (PCR) in 628 CRC cases and 1,256 age and sex frequency matched cancer-free controls. Odds ratios (OR) and 95% confidence intervals (95% CI) were calculated using unconditional logistic regression models to evaluate the association between RTL and CRC risk.

Results

Using median RTL in the controls as the cutoff, individuals with shorter RTL were associated with a significantly increased risk of CRC (adjusted OR = 1.27, 95%CI: 1.05–1.55). When participants were further categorized into 3 and 4 groups according to the tertile and quartile RTL values of controls, significant relationships were still observed between shorter RTL and increased CRC risk (OR per tertile = 1.13, 95%CI: 1.00–1.28, P_trend = 0.045; OR per quartile = 1.12, 95%CI: 1.03–1.23, P_trend = 0.012). In stratified analyses, significant association between shorter RTL and increased CRC risk was found in females, individuals younger than 60 years old, never smokers and never drinkers.

Conclusions

This study suggested that short telomere length in PBLs was significantly associated with an increased risk of CRC in Chinese Han population. Further validation in large prospective studies and investigation of the biologic mechanisms are warranted.

The role of telomere biology in cancer

Telomere biology plays a critical and complex role in the initiation and progression of cancer. Although telomere dysfunction resulting from replicative attrition constrains tumor growth by engaging DNA-damage signaling pathways, it can also promote tumorigenesis by causing oncogenic chromosomal rearrangements. Expression of the telomerase enzyme enables telomere-length homeostasis and allows tumor cells to escape the antiproliferative barrier posed by short telomeres. Telomeres and telomerase also function independently of one another. Recent work has suggested that telomerase promotes cell growth through pathways unrelated to telomere maintenance, and a subset of tumors elongate telomeres through telomerase-independent mechanisms. In an effort to exploit the integral link between telomere biology and cancer growth, investigators have developed several telomerase-based therapeutic strategies, which are currently in clinical trials. Here, we broadly review the state of the field with a particular focus on recent developments of interest.

Markers of field cancerization: proposed clinical applications in prostate biopsies

Field cancerization denotes the occurrence of genetic, epigenetic, and biochemical aberrations in structurally intact cells in histologically normal tissues adjacent to cancerous lesions. This paper tabulates markers of prostate field cancerization known to date and discusses their potential clinical value in the analysis of prostate biopsies, including diagnosis, monitoring progression during active surveillance, and assessing efficacy of presurgical neoadjuvant and focal therapeutic interventions.

Multiplex time-reducing quantitative polymerase chain reaction assay for determination of telomere length in blood and tissue DNA

In this paper we describe a multiplex time-reducing quantitative polymerase chain reaction (qPCR) method for determination of telomere length. This multiplex qPCR assay enables two pairs of primers to simultaneously amplify telomere and single copy gene (albumin) templates, thus reducing analysis time and labor compared with the previously established singleplex assay. The chemical composition of the master mix and primers for the telomere and albumin were systematically optimized. The thermal cycling program was designed to ensure complete separation of the melting processes of the telomere and albumin. Semi-log standard curves of DNA concentration versus cycle threshold (C (t)) were established, with a linear relationship over an 81-fold DNA concentration range. The well-performed intra-assay (RSD range 2.4-4.7%) and inter-assay (RSD range: 3.1-5.0%) reproducibility were demonstrated to ensure measurement stability. Using wild-type, Lewis lung carcinoma and H22 liver carcinoma C57BL/6 mouse models, significantly different telomere lengths among different DNA samples were not observed in wild-type mice. However, the relative telomere lengths of the tumor DNA in the two strains of tumor-bearing mice were significantly shorter than the lengths in the surrounding non-tumor DNA of tumor-bearing mice and the tissue DNA of wild-type mice. These results suggest that the shortening of telomere lengths may be regarded as an important indicator for cancer control and prevention. Quantification of telomere lengths was further confirmed by the traditional Southern blotting method. This method could be successfully used to reduce the time needed for rapid, precise measurement of telomere lengths in biological samples.

Prostate cancer as a model system for genetic diversity in tumors

This chapter will summarize novel understandings of the early molecular events in prostatic carcinogenesis that may underlie both the genetic and clinical heterogeneity. Areas covered include preneoplasia, stem cell concepts, telomere abnormalities, and the nature of tumor-stromal interactions. The oncogenomics of prostate cancer is reviewed with emphasis on androgen signaling, ETS gene family aberrations, and PTEN deletion. The notion that "field cancerization," coupled with genomic instability may explain both the occurrence of multifocal disease, and the recent observations of genetic diversity of ERG alteration in individual tumors are discussed. Collectively, genomic studies are rapidly moving human prostate cancer closer to the promise of personalized medicine, so that specific genetic profiles of individual tumors will determine the best therapeutic approaches.

The potential utility of telomere-related markers for cancer diagnosis

The role telomeres and telomerase play in the initiation and progression of human cancers has been extensively evaluated. Telomeres are nucleoprotein complexes comprising the hexanucleotide DNA repeat sequence, TTAGGG and numerous telomere-associated proteins, including the six member Shelterin complex. The main function of the telomere is to stabilize the ends of the chromosomes. However, through multiple mechanisms, telomeres can become dysfunctional, which may drive genomic instability leading to the development of cancer. The majority of human cancers maintain, or actively lengthen, telomeres through up-regulation of the reverse transcriptase telomerase. Because there are significant differences in telomere length and telomerase activity between malignant and non-malignant tissues, many investigations have assessed the potential to utilize these molecular markers for cancer diagnosis. Here, we critically evaluate whether measurements of telomere lengths and telomerase levels may be clinically utilized as diagnostic markers in solid tumours, with emphasis on breast and prostate cancer as representative examples. Future directions focusing on the direct detection of dysfunctional telomeres are explored. New markers for telomere dysfunction may eventually prove clinically useful.

Shortened telomere length is associated with increased risk of cancer: a meta-analysis

BACKGROUND

Telomeres play a key role in the maintenance of chromosome integrity and stability, and telomere shortening is involved in initiation and progression of malignancies. A series of epidemiological studies have examined the association between shortened telomeres and risk of cancers, but the findings remain conflicting.

METHODS

A dataset composed of 11,255 cases and 13,101 controls from 21 publications was included in a meta-analysis to evaluate the association between overall cancer risk or cancer-specific risk and the relative telomere length. Heterogeneity among studies and their publication bias were further assessed by the χ(2)-based Q statistic test and Egger's test, respectively.

RESULTS

The results showed that shorter telomeres were significantly associated with cancer risk (OR = 1.35, 95% CI = 1.14-1.60), compared with longer telomeres. In the stratified analysis by tumor type, the association remained significant in subgroups of bladder cancer (OR = 1.84, 95% CI = 1.38-2.44), lung cancer (OR = 2.39, 95% CI = 1.18-4.88), smoking-related cancers (OR = 2.25, 95% CI = 1.83-2.78), cancers in the digestive system (OR = 1.69, 95% CI = 1.53-1.87) and the urogenital system (OR = 1.73, 95% CI = 1.12-2.67). Furthermore, the results also indicated that the association between the relative telomere length and overall cancer risk was statistically significant in studies of Caucasian subjects, Asian subjects, retrospective designs, hospital-based controls and smaller sample sizes. Funnel plot and Egger's test suggested that there was no publication bias in the current meta-analysis (P = 0.532).

CONCLUSIONS

The results of this meta-analysis suggest that the presence of shortened telomeres may be a marker for susceptibility to human cancer, but single larger, well-design prospective studies are warranted to confirm these findings.

Topographical analysis of telomere length and correlation with genomic instability in whole mount prostatectomies

BACKGROUND

Many critical events in prostatic carcinogenesis appear to relate to the emergence of genomic instability. Characteristic genomic abnormalities such as 8p loss, 8q gain, trisomy 7, and PTEN microdeletions may provide selective advantages to increase neoplastic transformation. Evidence suggests that telomere dysfunction is a plausible mechanism for some of these abnormalities on the basis of the break-fusion-bridge cycle that can lead to manifestations of genomic instability.

METHODS

In this study, we correlate telomere length measured by quantitative FISH in various prostatic histologies with markers of genomic instability and immunohistochemical measures of proliferation and oxidative stress.

RESULTS

We find that telomere shortening is correlated with abnormalities on chromosome 8, but not with trisomy 7 or abnormalities of the PTEN locus. There are associations with C-MYC aberrations in stroma with greater proximity to cancer and a correlation between telomere length in a number of prostatic histologies and the adjacent stroma, suggesting the importance of microenvironmental effects on telomere maintenance in the prostate. This finding was also supported by the finding of the correlation between telomere attrition and the levels of oxidative stress as measured by malondialdehyde staining in HPIN lesions close to cancer.

CONCLUSIONS

Telomere attrition in the prostate gland is associated with particular genomic aberrations that contribute to the genomic instability characteristic of prostatic carcinogenesis. Correlations between various histologies and adjacent stroma telomere length suggest it is also may reveal microenvironmental effects within the prostate gland. Oxidative stress may contribute to telomere attrition in HPIN close to cancer.

Association between telomere length and C-reactive protein and the development of coronary collateral circulation in patients with coronary artery disease

BACKGROUND

Coronary collateral circulation is a stabilizer factor in myocardial ischemia. We attempted to establish a link between collateral circulation, C-reactive protein (CRP), and telomere shortening.

PATIENTS AND METHODS

A case-control study was performed in patients with (group A) and without (group B) coronary collaterals using coronariography. The patients were males, CRP levels and telomere length in circulating leucocytes were measured; Student t test and logistic regression were used to analyze the data.

RESULTS

The study included 40 patients aged 53.9 ± 7.0 years (20 per group). Group A exhibited lower CRP levels (2.76 ± 3.34 vs 4.04 ± 3.38; P = .004); whereas telomere length was shorter in group B (2.3 ± 6.9 kb vs 6.1 ± 5.9 kb; P < .0001).

CONCLUSIONS

Collateral circulation was associated with telomere shortening and elevation of CRP levels.

Telomere dynamics in keloids

OBJECTIVE

Little is known about telomere dynamics in keloids. As keloid formation is dependent on cell replication, in theory telomeres should be shorter in keloids than in normal skin. We examined this concept in the present study.

METHODS

We measured by Southern blot analysis telomere length in keloids and in adjacent normal skin of 16 individuals. When available, we also measured telomere length in blood (leukocytes) and subcutaneous fat.

RESULTS

Telomere length was highly variable among individuals but highly correlated among tissues (cells) within the individual. The mean telomere length in the keloids was longer than that in the adjacent normal skin and displayed a length gradient, with the mean length of telomeres shorter just below the epidermis and longer at the base of the keloids. No apparent telomerase activity was detected in the keloids.

CONCLUSIONS

Our findings suggest a transient activation of telomerase, the reverse transcriptase that prevents telomere shortening, probably during the early phase of keloid formation. The activation of telomerase serves to maintain (or even elongate) telomere length in the keloid. However, telomerase activity is repressed in the fully developed keloid.

Molecular genetics of prostate cancer: new prospects for old challenges

Despite much recent progress, prostate cancer continues to represent a major cause of cancer-related mortality and morbidity in men. Since early studies on the role of the androgen receptor that led to the advent of androgen deprivation therapy in the 1940s, there has long been intensive interest in the basic mechanisms underlying prostate cancer initiation and progression, as well as the potential to target these processes for therapeutic intervention. Here, we present an overview of major themes in prostate cancer research, focusing on current knowledge of principal events in cancer initiation and progression. We discuss recent advances, including new insights into the mechanisms of castration resistance, identification of stem cells and tumor-initiating cells, and development of mouse models for preclinical evaluation of novel therapuetics. Overall, we highlight the tremendous research progress made in recent years, and underscore the challenges that lie ahead.

Organ-wide telomeric status in diseased and disease-free prostatic tissues

BACKGROUND

Telomere attrition occurs early in the development of prostatic adenocarcinoma. However, little is known about either telomere status in benign prostatic hyperplasia (BPH), or the spatial and organ-wide distribution of potential telomere aberrations throughout all areas of prostatic glands affected by cancer or BPH.

METHODS

Slot blot titration assay was used to determine telomere DNA content (TC), a proxy for telomere length, in macrodissected tissue consisting of 54 normal samples from 5 disease-free prostates, 128 BPH samples from 4 non-cancerous prostates, and 45 tumor, 73 BPH, and 4 prostatic intraepithelial neoplasia (PIN) samples from 5 cancerous prostates.

RESULTS

Compared to TC in normal prostate samples (n = 54; TC mean = 0.98), tumor samples displayed telomere attrition (n = 45; TC mean = 0.67). TC in PIN samples was similar to tumors. TC in BPH samples from cancerous prostates was similar to TC in tumors and also displayed telomere shortening (n = 73; TC mean = 0.76), whereas BPH samples from non-cancerous prostates displayed longer telomeres (n = 128; TC mean = 1.06). In prostates affected by adenocarcinoma, areas of potential telomere attrition occurred in histologically normal tissues through the entire gland. However, three-dimensional zoning revealed a pattern of increasing TC as a function of distance from the primary (index) tumor.

CONCLUSIONS

Spatial distributions of TC in prostate specimens indicate a complex "field effect" with varying contributions from both cancer and BPH. The observation that telomere length variations occur in fields of histologically normal tissues surrounding the tumor is of clinical importance, as it may have implications for the diagnosis and focal therapy of prostate cancer.

The War on Cancer rages on

In 1971, the "War on Cancer" was launched by the US government to cure cancer by the 200-year anniversary of the founding of the United States of America, 1976. This article briefly looks back at the progress that has been made in cancer research and compares progress made in other areas of human affliction. While progress has indeed been made, the battle continues to rage on.

Leukocyte telomere length in a population-based case-control study of ovarian cancer: a pilot study

OBJECTIVES

Telomeres are structures at chromosome ends that contribute to maintaining genomic integrity. Telomere shortening with repeated cell divisions may lead to genomic instability and carcinogenesis. Studies suggest that shorter telomeres in constitutional DNA are associated with bladder, breast, lung, and renal cancer. Ovarian cancer tissues also have shortened telomeres and increased telomerase activity, suggesting that telomere abnormalities may be related to ovarian cancer.

METHODS

We investigated leukocyte telomere length in 99 women with serous ovarian adenocarcinoma and 100 age-matched cancer-free controls enrolled in a population-based case-control study.

RESULTS

Cases tended to have shorter telomeres than controls (P (wilcoxon) = 0.002). Compared to subjects with telomere lengths in the longest tertile, those in the middle and shortest tertiles showed respective age-adjusted odds ratios (95% confidence intervals) of 2.69 (1.23-5.88) and 3.39 (1.54-7.46) (P (trend) = 0.002). Strongest associations were found for subjects with poorly differentiated carcinomas (OR = 4.89, 95% CI 1.93-12.34).

CONCLUSIONS

This study shows that short leukocyte telomeres are associated with serous ovarian adenocarcinoma. These findings should be confirmed in large, prospective studies.

The association between leukocyte telomere length and cigarette smoking, dietary and physical variables, and risk of prostate cancer

Telomeres consist of nucleotide repeats and a protein complex at chromosome ends that are essential to maintaining chromosomal integrity. Several studies have suggested that subjects with shorter telomeres are at increased risk of bladder and lung cancer. In comparison to normal tissues, telomeres are shorter in high-grade intraepithelial neoplasia and prostate cancer. We examined prostate cancer risk associated with relative telomere length as determined by quantitative PCR on prediagnostic buffy coat DNA isolated from 612 advanced prostate cancer cases and 1049 age-matched, cancer-free controls from the PLCO Cancer Screening Trial. Telomere length was analyzed as both a continuous and a categorical variable with adjustment for potential confounders. Statistically significant inverse correlations between telomere length, age and smoking status were observed in cases and controls. Telomere length was not associated with prostate cancer risk (at the median, OR = 0.85, 95% CI: 0.67, 1.08); associations were similar when telomere length was evaluated as a continuous variable or by quartiles. The relationships between telomere length and inflammation-related factors, diet, exercise, body mass index, and other lifestyle variables were explored since many of these have previously been associated with shorter telomeres. Healthy lifestyle factors (i.e., lower BMI, more exercise, tobacco abstinence, diets high in fruit and vegetables) tended to be associated with greater telomere length. This study found no statistically significant association between leukocyte telomere length and advanced prostate cancer risk. However, correlations of telomere length with healthy lifestyles were noted, suggesting the role of these factors in telomere biology maintenance and potentially impacting overall health status.

Telomere DNA content in prostate biopsies predicts early rise in prostate-specific antigen after radical prostatectomy for prostate cancer

OBJECTIVE

To determine whether measurement of telomere DNA content (TC) in prostate biopsy tissue predicts prostate-specific antigen (PSA) recurrence in men after undergoing radical prostatectomy for prostate cancer.

METHODS

Slot blot titration assay was used to quantitate TC in archived diagnostic prostate needle biopsy specimens for subjects (n = 103) diagnosed with prostate cancer and who subsequently underwent radical prostatectomy between 1993 and 1997. TC was compared to the clinical outcome measure; PSA recurrence, defined as an increase in PSA > or = 0.2 ng/mL on 2 or more consecutive measurements post-prostatectomy, was observed retrospectively, for a mean follow-up period of 114 months (range, 1-165).

RESULTS

In the cohort, 46 subjects had a PSA recurrence. In a univariate Cox proportional hazards model, low TC (< 0.3 of standard) demonstrated a significant risk for PSA recurrence (HR = 1.94; 95% CI: 1.02-3.69, P = .04). In a subset analysis of men with biopsy Gleason sum < or = 6 (n = 63; 25 recurrences), a univariate Cox proportional hazards model demonstrated that low TC had a greater risk of PSA recurrence (HR = 4.53; 95% CI: 2.00-10.2, P < .01). In a multivariate Cox proportional hazards model, low TC was also significantly associated with PSA recurrence in this subset after controlling for preoperative PSA levels (HR = 6.62; 95% CI: 2.69-16.3, P < .01).

CONCLUSIONS

Low TC measured in prostate biopsy tissue predicts early likelihood of post-prostatectomy PSA recurrence in a retrospective analysis, and in men with biopsy Gleason sum < or = 6 disease it is also independent of preoperative PSA level.

Neoplasia: the second decade

This issue marks the end of the 10-year anniversary of Neoplasia where we have seen exciting growth in both number of submitted and published articles in Neoplasia. Neoplasia was first published in 1999. During the past 10 years, Neoplasia has dynamically adapted to the needs of the cancer research community as technologies have advanced. Neoplasia is currently providing access to articles through PubMed Central to continue to facilitate rapid broad-based dissemination of published findings to the scientific community through an Open Access model. This has in part helped Neoplasia to achieve an improved impact factor this past year, demonstrating that the manuscripts published by Neoplasia are of great interest to the overall cancer research community. This past year, Neoplasia received a record number of articles for review and has had a 21% increase in the number of published articles.

Telomere attrition in cancer cells and telomere length in tumor stroma cells predict chromosome instability in esophageal squamous cell carcinoma: a genome-wide analysis

Previous studies showed that chromosomal instability was common in esophageal squamous cell carcinoma (ESCC); however, the mechanisms underlying this instability are unknown. Individuals with deficiencies in telomere maintenance are susceptible to enhanced telomere loss during cell proliferation; such deficiencies could result in telomere dysfunction and genomic instability. We investigated the association between genome-wide chromosomal changes in cancer cells and telomere length/attrition in cancer/stroma cells in 47 ESCC patients. Genome-wide detection of loss of heterozygosity was performed using the Affymetrix GeneChip single nucleotide polymorphism arrays. Telomere length was assessed separately for cancer cells, carcinoma-associated fibroblasts (CAF), infiltrative lymphocytes, and adjacent normal epithelial cells by quantitative fluorescent in situ hybridization using paraffin-embedded sections. Telomere length differed significantly among cell types, such that length in infiltrative lymphocytes > CAFs > cancer cells. Shortened telomeres were observed in cancer cells in 44 of 47 (94%) of the tumors examined. Telomere length in CAFs was significantly associated with chromosomal instability on 4q and 13q and lymphocyte telomere length was significantly associated with instability on chromosomal arms 15q. Although telomere length in cancer cells was not associated with chromosome arm instability, telomere attrition in cancer cells, defined as the telomere length in CAFs minus the telomere length in cancer cells, was significantly associated with chromosomal instability on 13q and 15q. This study provides evidence that telomere shortening is a common genetic alteration in ESCC and that chromosome arm instability is related to both telomere attrition in cancer cells and telomere length in tumor stroma cells.

Molecular Pathology of the Genitourinary Tract: Prostate and Bladder

The knowledge of cellular mechanisms in tumors of the prostate and bladder has grown exponentially. Molecular technologies have led to the discovery of TMPRSS2 in prostate cancer and the molecular pathways distinguishing low- and high-grade urothelial neoplasms. UroVysion with fluorescence in situ hybridization is already commonplace as an adjunct to cytologic diagnosis of urothelial neoplasms. This trend portends the future in which classification and diagnosis of tumors of the prostate and bladder through morphologic analysis will be supplemented by molecular information correlating with prognosis and targeted therapy. This article outlines tumor molecular pathology of the prostate and bladder encompassing current genomic, epigenomic, and proteonomic findings.

Loss of RB1 induces non-proliferative retinoma: increasing genomic instability correlates with progression to retinoblastoma

Retinoblastoma clinical observations revealed the role of tumor suppressor genes in human cancer, Knudson's 'two-hit' model of cancer induction. We now demonstrate that loss of both RB1 tumor suppressor gene alleles initiates quiescent RB1(-/-) retinomas with low level genomic instability and high expression of the senescence-associated proteins p16(INK4a) and p130. Although retinomas can remain unchanged throughout life, highly proliferative, clonal and aneuploid retinoblastomas commonly emerge, exhibiting altered gene copy number and expression of oncogenes (MYCN, E2F3, DEK, KIF14 and MDM4) and tumor suppressor genes (CDH11, p75(NTR)) and reduced expression of p16(INK4a) and p130. We suggest that RB1 inactivation in developing retina induces genomic instability, but senescence can block transformation at the stage of retinoma. However, stable retinoma is rarely clinically observed because progressive genomic instability commonly leads to highly proliferative retinoblastoma.

Telomere instability and cancer

Telomeres are required to preserve genome integrity, chromosome stability, nuclear architecture and chromosome pairing during meiosis. Given that telomerase activity is limiting or absent in most somatic tissues, shortening of telomeres during development and aging is the rule. In vitro, telomere length operates as a mechanism to prevent uncontrolled cell growth and therefore defines the proliferation potential of a cell. In vitro, in somatic cells that have lost proliferation control, shortening of telomeres becomes the main source of genome instability leading to genetic or epigenetic changes that may allow cells to become immortal and to acquire tumor phenotypes. In vivo, mice models have indisputably shown both the protective and the promoting role of very short telomeres in cancer development. In humans, although telomere shortening and other types of telomere dysfunction probably contribute to the genome instability often detected in tumors, the specific contributions of such instability to the development of cancer remain largely undetermined.

Cancer statistics, 2007

Each year, the American Cancer Society (ACS) estimates the number of new cancer cases and deaths expected in the United States in the current year and compiles the most recent data on cancer incidence, mortality, and survival based on incidence data from the National Cancer Institute, Centers for Disease Control and Prevention, and the North American Association of Central Cancer Registries and mortality data from the National Center for Health Statistics. This report considers incidence data through 2003 and mortality data through 2004. Incidence and death rates are age-standardized to the 2000 US standard million population. A total of 1,444,920 new cancer cases and 559,650 deaths for cancers are projected to occur in the United States in 2007. Notable trends in cancer incidence and mortality rates include stabilization of the age-standardized, delay-adjusted incidence rates for all cancers combined in men from 1995 through 2003; a continuing increase in the incidence rate by 0.3% per year in women; and a 13.6% total decrease in age-standardized cancer death rates among men and women combined between 1991 and 2004. This report also examines cancer incidence, mortality, and survival by site, sex, race/ethnicity, geographic area, and calendar year, as well as the proportionate contribution of selected sites to the overall trends. While the absolute number of cancer deaths decreased for the second consecutive year in the United States (by more than 3,000 from 2003 to 2004) and much progress has been made in reducing mortality rates and improving survival, cancer still accounts for more deaths than heart disease in persons under age 85 years. Further progress can be accelerated by supporting new discoveries and by applying existing cancer control knowledge across all segments of the population.