Prostate stromal cell telomere shortening is associated with risk of prostate cancer in the placebo arm of the Prostate Cancer Prevention Trial

Mendelian randomization evidence based on European ancestry for the causal effects of leukocyte telomere length on prostate cancer

BACKGROUND

Several lines of evidence suggest that leukocyte telomere length (LTL) can affect the development of prostate cancer (PC).

METHODS

Here, we employed single nucleoside polymorphisms (SNPs) as instrumental variables (IVs) for LTL (n = 472,174) and conducted Mendelian randomization analysis to estimate their causal impact on PCs (79,148 patients/61,106 controls and 6311 patients/88,902 controls).

RESULTS

Every 1-s.d extension of LTL increased the risk of PCs by 34%. Additionally, the analysis of candidate mediators between LTL and PCs via two-step Mendelian randomization revealed that among the 23 candidates, Alzheimer's disease, liver iron content, sex hormone binding global levels, naive CD4-CD8-T cell% T cell, and circulating leptin levels played substantial mediating roles. There is no robust evidence to support the reverse causal relationship between LTL and the selected mediators of PCs. Adjusting for the former four mediators, rather than adjusting for circulating leptin levels, decreased the impact of LTL on PCs.

CONCLUSION

This study provides potential intervention measures for preventing LTL-induced PCs.

Longer prostate stromal cell telomere length is associated with increased risk of death from other cancers

Background

Telomeres are located at chromosomal termini and function to maintain genomic integrity. Telomere dysfunction is a well-recognized contributor to aging and age-related diseases, such as prostate cancer. Since telomere length is highly heritable, we postulate that stromal cell telomere length in the tissue of a particular solid organ may generally reflect constitutive stromal cell telomere length in other solid organs throughout the body. Even with telomere loss occurring with each round of cell replication, in general, telomere length in prostate stromal cells in mid-life would still be correlated with the telomere length in stromal cells in other organs. Thus, we hypothesize that prostate stromal cell telomere length and/or telomere length variability is a potential indicator of the likelihood of developing future solid cancers, beyond prostate cancer, and especially lethal cancer.

Methods

To explore this hypothesis, we conducted a cohort study analysis of 1,175 men who were surgically treated for prostate cancer and were followed for death, including from causes other than their prostate cancer.

Results

In this cohort study with a median follow-up of 19 years, we observed that longer prostate stromal cell telomere length measured in tissue microarray spots containing prostate cancer was associated with an increased risk of death from other solid cancers. Variability in telomere length among these prostate stromal cells was possibly positively associated with risk of death from other solid cancers.

Conclusion

Studying the link between stromal cell telomere length and cancer mortality may be important for guiding the development of cancer interception and prevention strategies.

Prognostic and therapeutic potential of senescent stromal fibroblasts in prostate cancer

The stromal component of the tumour microenvironment in primary and metastatic prostate cancer can influence and promote disease progression. Within the prostatic stroma, fibroblasts are one of the most prevalent cell types associated with precancerous and cancerous lesions; they have a vital role in the structural composition, organization and integrity of the extracellular matrix. Fibroblasts within the tumour microenvironment can undergo cellular senescence, which is a stable arrest of cell growth and a phenomenon that is emerging as a recognized hallmark of cancer. Supporting the idea that cellular senescence has a pro-tumorigenic role, a subset of senescent cells exhibits a senescence-associated secretory phenotype (SASP), which, along with increased inflammation, can promote prostate cancer cell growth and survival. These cellular characteristics make targeting senescent cells and/or modulating SASP attractive as a potential preventive or therapeutic option for prostate cancer.

The Hallmarks of Precancer

Research on precancers, as defined as at-risk tissues and early lesions, is of high significance given the effectiveness of early intervention. We discuss the need for risk stratification to prevent overtreatment, an emphasis on the role of genetic and epigenetic aging when considering risk, and the importance of integrating macroenvironmental risk factors with molecules and cells in lesions and at-risk normal tissues for developing effective intervention and health policy strategies.

Chromogenic detection of telomere lengths in situ aids the identification of precancerous lesions in the prostate

BACKGROUND

Telomeres are terminal chromosomal elements that are essential for the maintenance of genomic integrity. The measurement of telomere content provides useful diagnostic and prognostic information, and fluorescent methods have been developed for this purpose. However, fluorescent-based tissue assays are cumbersome for investigators to undertake, both in research and clinical settings.

METHODS

A robust chromogenic in situ hybridization (CISH) approach was developed to visualize and quantify telomere content at single cell resolution in human prostate tissues, both frozen and formalin-fixed, paraffin-embedded (FFPE).

RESULTS

This new assay (telomere chromogenic in situ hybridization ["Telo-CISH"]) produces permanently stained slides that are viewable with a standard light microscope, thus avoiding the need for specialized equipment and storage. The assay is compatible with standard immunohistochemistry, thereby allowing simultaneous assessment of histomorphology, identification of specific cell types, and assessment of telomere status. In addition, Telo-CISH eliminates the problem of autofluorescent interference that frequently occurs with fluorescent-based methods. Using this new assay, we demonstrate successful application of Telo-CISH to help identify precancerous lesions in the prostate by the presence of markedly short telomeres specifically in the luminal epithelial cells.

CONCLUSIONS

In summary, with fewer restrictions on the types of tissues that can be tested, and increased histologic information provided, the advantages presented by this novel chromogenic assay should extend the applicability of tissue-based telomere length assessment in research and clinical settings.

NRF2 signaling pathway and telomere length in aging and age-related diseases

The transcription factor nuclear factor erythroid 2-related factor 2 (NRF2) is well recognized as a critical regulator of redox, metabolic, and protein homeostasis, as well as the regulation of inflammation. An age-associated decline in NRF2 activity may allow oxidative stress to remain unmitigated and affect key features associated with the aging phenotype, including telomere shortening. Telomeres, the protective caps of eukaryotic chromosomes, are highly susceptible to oxidative DNA damage, which can accelerate telomere shortening and, consequently, lead to premature senescence and genomic instability. In this review, we explore how the dysregulation of NRF2, coupled with an increase in oxidative stress, might be a major determinant of telomere shortening and age-related diseases. We discuss the relevance of the connection between NRF2 deficiency in aging and telomere attrition, emphasizing the importance of studying this functional link to enhance our understanding of aging pathologies. Finally, we present a number of compounds that possess the ability to restore NRF2 function, maintain a proper redox balance, and preserve telomere length during aging.

The prostate tissue‐based telomere biomarker as a prognostic tool for metastasis and death from prostate cancer after prostatectomy

Current biomarkers are inadequate prognostic predictors in localized prostate cancer making treatment decision‐making challenging. Previously, we observed that the combination of more variable telomere length among prostate cancer cells and shorter telomere length in prostate cancer‐associated stromal cells – the telomere biomarker – is strongly associated with progression to metastasis and prostate cancer death after prostatectomy independent of currently used pathologic indicators. Here, we optimized our method allowing for semi‐automated telomere length determination in single cells in fixed tissue, and tested the telomere biomarker in five cohort studies of men surgically treated for clinically localized disease (N = 2,255). We estimated the relative risk (RR) of progression to metastasis (N = 311) and prostate cancer death (N = 85) using models appropriate to each study's design adjusting for age, prostatectomy stage, and tumor grade, which then we meta‐analyzed using inverse variance weights. Compared with men who had less variable telomere length among prostate cancer cells and longer telomere length in prostate cancer‐associated stromal cells, men with the combination of more variable and shorter telomere length had 3.76 times the risk of prostate cancer death (95% confidence interval [CI] 1.37–10.3, p = 0.01) and had 2.23 times the risk of progression to metastasis (95% CI 0.99–5.02, p = 0.05). The telomere biomarker was associated with prostate cancer death in men with intermediate risk disease (grade groups 2/3: RR = 9.18, 95% CI 1.14–74.0, p = 0.037) and with PTEN protein intact tumors (RR = 6.74, 95% CI 1.46–37.6, p = 0.015). In summary, the telomere biomarker is robust and associated with poor outcome independent of current pathologic indicators in surgically treated men.

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.

Fibroblast heterogeneity in prostate carcinogenesis

Our understanding of stromal components, specifically cancer-associated fibroblasts (CAF), in prostate cancer (PCa), has evolved from considering these cells as inert bystanders to acknowledging their significance as players in prostate tumorigenesis. CAF are multifaceted-they promote cancer cell growth, migration and remodel the tumor microenvironment. Although targeting CAF could be a promising strategy for PCa treatment, they incorporate a high but undefined degree of intrinsic cellular heterogeneity. The interaction between CAF subpopulations, with the normal and tumor epithelium and with other cell types is not yet characterized. Defining these interactions and the critical signaling nodes that support tumorigenesis will enable the development of novel strategies to control prostate cancer progression. Here we will discuss the origins, molecular and functional heterogeneity of CAF in PCa. We highlight the challenges associated with delineating CAF heterogeneity and discuss potential areas of research that would assist in expanding our knowledge of CAF and their role in PCa tumorigenesis.

Telomeres and Age-Related Diseases

Telomeres are at the non-coding ends of linear chromosomes. Through a complex 3-dimensional structure, they protect the coding DNA and ensure appropriate separation of chromosomes. Aging is characterized by a progressive shortening of telomeres, which compromises their structure and function. Because of their protective function for genomic DNA, telomeres appear to play an important role in the development and progression of many age-related diseases, such as cardiovascular disease (CVD), malignancies, dementia, and osteoporosis. Despite substantial evidence that links telomere length with these conditions, the nature of these observations remains insufficiently understood. Therefore, future studies should address the question of causality. Furthermore, analytical methods should be further improved with the aim to provide informative and comparable results. This review summarize the actual knowledge of telomere biology and the possible implications of telomere dysfunction for the development and progression of age-related diseases. Furthermore, we provide an overview of analytical techniques for the measurement of telomere length and telomerase activity.

What telomeres teach us about MS

While the precise mechanisms driving progressive forms of MS are not fully understood, patient age has clear impact on disease phenotype. The very young with MS have high relapse rates and virtually no progressive disease, whereas older patients tend to experience more rapid disability accumulation with few relapses. Defining a patient's biological age may offer more precision in determining the role of aging processes in MS phenotype and pathophysiology than just working with an individual's birthdate. The most well recognized measurement of an individual's "biological clock" is telomere length (TL). While TL may differ across tissue types in an individual, most cells TL correlate well with leukocyte TL (LTL), which is the most common biomarker used for aging. LTL has been associated with risk for aging related diseases and most recently with higher levels of disability and brain atrophy in people living with MS. LTL explains 15% of the overall association of chronological age with MS disability level. While LTL may be used just as a biomarker of overall somatic aging processes, triggering of the DNA damage response by telomere attrition leads to senescence pathways that are likely highly relevant to a chronic autoimmune disease. Considering reproductive aging factors, particularly ovarian aging in women, which correlates with LTL and oocyte telomere length, may complement measurements of somatic aging in understanding MS progression. The key to stopping non-relapse related progression in MS might lie in targeting pathways related to biological aging effects on the immune and nervous systems.

Association of TERT gene polymorphisms with clinical benign prostatic hyperplasia in a Chinese Han population of the Northwest region

Background

To investigate the association between single nucleotide polymorphisms (rs10078761, rs12696304, rs2853669, rs16847897, rs2736100, rs10069690) of telomerase gene (TERT) and the risk clinical benign prostatic hyperplasia (BPH) in a Chinese Han population of the Northwest region.

Methods

A total of 150 BPH patients and 150 healthy older males from the northwest Chinese Han population were included in this study. The sample size for this unmatched case-control study was estimated by the look-up table method. Meanwhile, the general information and disease data of patients were collected. Age was only collected in healthy control subjects for statistical correction. Genotypes were detected using a multiplex PCR + ligase detection reaction (LDR). Typing results and clinical data were statistically analyzed using multiple linear regression and logistic regression. Pearson correlation was used for Hardy-Weinberg equilibrium.

Results

The included population is in Hardy-Weinberg equilibrium. There was no significant association between SNP and the risk of BPH by correlation analysis. However, 4 haplotypes (TCTGGT, TCTGTC, TGCCTC, and TGTGTC) were identified as risk factors of BPH by haplotype analysis. The SNP rs2853669 is an independent risk factor for smooth muscle type of hyperplasia. Besides, rs2736100, rs10078761, and rs10069690 which are in linkage disequilibrium are associated with the severity of BPH.

Conclusions

Polymorphism of the TERT gene determines the different disease development and pathological manifestations of BPH in the Chinese Han population the Northwest region.

Telomere lengths differ significantly between small-cell neuroendocrine prostate carcinoma and adenocarcinoma of the prostate

Small-cell neuroendocrine carcinoma (SCNC) of the prostate is an aggressive subtype with frequent TP53 mutation and RB1 inactivation; however, the molecular phenotype remains an area of investigation. Here, we compared telomere lengths in prostatic SCNC and usual-type prostatic adenocarcinoma (AdCa). We studied 32 cases of prostatic SCNC (including 11 cases with concurrent AdCa) and 347 cases of usual-type AdCa on tissue microarrays. Telomere lengths in tumor cells were qualitatively compared with those in normal cells using a telomere-specific fluorescence in situ hybridization assay. ERG, PTEN, and TP53 status were assessed in a proportion of cases using genetically validated immunohistochemistry protocols. Clinicopathological and molecular characteristics of cases were compared between the telomere groups using the chi-square test.A significantly higher proportion of prostatic SCNC cases (50%, 16/32) showed normal/long telomeres compared with AdCa cases (11%, 39/347; P < 0.0001). In 82% (9/11) of cases with concurrent SCNC and AdCa, the paired components were concordant for telomere length status. Among AdCa cases, the proportion of cases with normal/long telomeres significantly increased with increasing tumor grade group (P = 0.01) and pathologic stage (P = 0.02). Cases with normal/long telomeres were more likely to be ERG positive (P = 0.04) and to have TP53 missense mutation (P = 0.01) than cases with short telomeres.Normal or long telomere lengths are significantly more common in prostatic SCNC than in AdCa and are similar between concurrent SCNC and AdCa tumors, supporting a common origin. Among AdCa cases, longer telomere lengths are significantly associated with high-risk pathologic and molecular features.

Racial Difference in Prostate Cancer Cell Telomere Lengths in Men with Higher Grade Prostate Cancer: A Clue to the Racial Disparity in Prostate Cancer Outcomes

BACKGROUND

Black men have worse prostate cancer outcomes following treatment than White men even when accounting for prognostic factors. However, biological explanations for this racial disparity have not been fully identified. We previously showed that more variable telomere lengths among cancer cells and shorter telomere lengths in cancer-associated stromal (CAS) cells individually and together ("telomere biomarker") are associated with prostate cancer-related death in surgically treated men independent of currently used prognostic indicators. Here, we hypothesize that Black-White differences in the telomere biomarker and/or in its components may help explain the racial disparity in prostate cancer outcomes.

METHODS

Black [higher grade (Gleason ≥4+3) = 34 and lower grade = 93] and White (higher grade = 34 and lower grade = 89) surgically treated men were frequency matched on age, pathologic stage, and grade. We measured telomere lengths in cancer and CAS cells using a robust telomere-specific FISH assay. Tissue microarray and grade-specific distributional cutoff points without regard to race were evaluated.

RESULTS

Among men with higher grade disease, the proportion of Black men (47.1%) with more variable cancer cell telomere lengths was 2.3-times higher (P = 0.02) than that in White men (20.6%). In contrast, among men with lower grade disease, cancer cell telomere length variability did not differ by race. The proportion of men with shorter CAS cell telomeres did not differ by race for either higher or lower grade disease.

CONCLUSIONS

A greater proportion of Black men with higher grade disease have an adverse prostate cancer cell telomere phenotype than White men with higher grade disease.

IMPACT

Our findings suggest a possible explanation for the racial disparity in prostate cancer outcomes.

The protective function of non-coding DNA in DNA damage accumulation with age and its roles in age-related diseases

Aging is a progressive decline of physiological function in tissue and organ accompanying both accumulation of DNA damage and reduction of non-coding DNA. Peripheral non-coding DNA/heterochromatin has been proposed to protect the genome and centrally-located protein-coding sequences in soma and male germ cells against radiation and the invasion of exogenous nucleic acids. Therefore, this review summarizes the reduction of non-coding DNA/heterochromatin (including telomeric DNA and rDNA) and DNA damage accumulation during normal physiological aging and in various aging-related diseases. Based on analysis of data, it is found that DNA damage accumulation is roughly negatively correlated with the reduction of non-coding DNA and therefore speculated that DNA damage accumulation is likely due to the reduction of non-coding DNA protection in genome defense during aging. Therefore, it is proposed here that means to increase the total amount of non-coding DNA and/or heterochromatin prior to the onset of these diseases could potentially better protect the genome and protein-coding DNA, reduce the incidence of aging-related diseases, and thus lead to better health during aging.

Long-Term Dynamics of Three Dimensional Telomere Profiles in Circulating Tumor Cells in High-Risk Prostate Cancer Patients Undergoing Androgen-Deprivation and Radiation Therapy

Patient-specific assessment, disease monitoring, and the development of an accurate early surrogate of the therapeutic efficacy of locally advanced prostate cancer still remain a clinical challenge. Contrary to prostate biopsies, circulating tumor cell (CTC) collection from blood is a less-invasive method and has potential as a real-time liquid biopsy and as a surrogate marker for treatment efficacy. In this study, we used size-based filtration to isolate CTCs from the blood of 100 prostate cancer patients with high-risk localized disease. CTCs from five time points: +0, +2, +6, +12 and +24 months were analyzed. Consenting treatment-naïve patients with cT3, Gleason 8-10, or prostate-specific antigen > 20 ng/mL and non-metastatic prostate cancer were included. For all time points, we performed 3D telomere-specific quantitative fluorescence in situ hybridization on a minimum of thirty isolated CTCs. The patients were divided into five groups based on the changes of number of telomeres vs. telomere lengths over time and into three clusters based on all telomere parameters found on diagnosis. Group 2 was classified as non-respondent to treatment and the Cluster 3 presented more aggressive phenotype. Additionally, we compared our telomere results with the PSA levels for each patient at 6 months of ADT, at 6 months of completed RT, and at 36 months post-initial therapy. CTCs of patients with PSA levels above or equal to 0.1 ng/mL presented significant increases of nuclear volume, number of telomeres, and telomere aggregates. The 3D telomere analysis of CTCs identified disease heterogeneity among a clinically homogeneous group of patients, which suggests differences in therapeutic responses. Our finding suggests a new opportunity for better treatment monitoring of patients with localized high-risk prostate cancer.

Telomere biology and age-related diseases

Telomeres are the protective end caps of chromosomes and shorten with every cell division. Telomere length has been proposed as a biomarker of biological age and a risk factor for age-related diseases. Epidemiologic studies show an association between leukocyte telomere length (LTL) and mortality. There is solid evidence that links LTL with cardiovascular disease. Short telomeres promote atherosclerosis and impair the repair of vascular lesions. Alzheimer's disease patients have also a reduced LTL. Telomeres measured in tumor tissue from breast, colon and prostate are shorter than in healthy tissue from the same organ and the same patient. In healthy tissue directly adjacent to these tumors, telomeres are also shorter than in cells that are more distant from the cancerous lesion. A reduced telomere length in cancer tissue from breast, colon and prostate is associated with an advanced disease state at diagnosis, faster disease progression and poorer survival. By contrast, results regarding LTL and cancer are inconsistent. Furthermore, the majority of studies did not find significant associations between LTL, bone mineral density (BMD) and osteoporosis. The present manuscript gives an overview about our current understanding of telomere biology and reviews existing knowledge regarding the relationship between telomere length and age-related diseases.

Adding the Team into T1 Translational Research: A Case Study of Multidisciplinary Team Science in the Evaluation of Biomarkers of Prostate Cancer Risk and Prognosis

BACKGROUND

Given translational research challenges, multidisciplinary team science is promoted to increase the likelihood of moving from discovery to health effect. We present a case study documenting the utility of multidisciplinary team science in prostate cancer tissue biomarker validation.

METHODS

We used primary data generated by a team consisting of a pathologist, cancer biologists, a biostatistician, and epidemiologists. We examined their contributions by phase of biomarker evaluation to identify when, through the practice of team science, threats to internal validity were recognized and solved. Next, we quantified the extent of bias avoided in evaluating the association of Ki67 (immunohistochemistry), stromal cell telomere length (fluorescence in situ hybridization), and microRNA (miRNA) (miR-21, miR-141, miR-221; quantitative RT-PCR) with prostate cancer risk or recurrence in nested case-control studies.

RESULTS

Threats to validity were tissue storage time (Ki67, miRNA) and laboratory equipment maintenance (telomeres). Solutions were all in the data analysis phase and involved using tissue storage-time specific cutpoints and/or batch-specific cutpoints. Bias in the regression coefficient for quantiles of each biomarker ranged from 24% to 423%, and the coefficient for the test for trend ranged from 15% to 910%. The interpretation of the associations changed as follows: Ki67, null to positive; stromal cell telomere length, null to positive; miR-21 and miR-141 remained null; miR-221, weak to moderate inverse.

CONCLUSIONS

In this case study, we documented the inferential benefits of multidisciplinary team science when the team's collaboration and coordination led to the identification of threats to validity and the implementation of appropriate solutions.

Cancer telomeres and white crows

This mini-review article discusses past and present prostate-focused research on telomere and telomerase biology conducted at Johns Hopkins, through the eyes of a Donald S Coffey trainee. Included are past discoveries of abnormalities in telomere biology in the context of prostate cancer and its pre-malignant precursor prostatic intraepithelial neoplasia (PIN); the finding that telomerase activity is androgen-regulated in the prostate, and the potential role of telomerase in prostate epithelial stem cells. Also reviewed are more recent results showing that in situ telomere length measurements in patient tissue specimens may have utility in risk assessment and as a prognostic biomarker. Highlighted throughout the article are some of the training and mentorship approaches employed by the late Dr. Coffey, former Director of Urologic Research at the Brady Urological Research Institute, which inspired new research ideas, team science, and discovery.

Prostate cancer susceptibility and growth linked to Y chromosome genes

The role of Y chromosome in prostate cancer progression and incidence is not well known. Among the 46 chromosomes, Y chromosome determines the male gender. The Y chromosome is smaller than the X chromosome and contains only 458 genes compared to over 2000 genes found in the X chromosome. The Y chromosome is prone to high mutation rates, created exclusively in sperm cells due to the highly oxidative environment of the testis. Y chromosome harbors epigenetic information, which affects the expression of genes associated with the incidence and progression of prostate cancer. In this review, we focus on Y chromosome related genetic abnormalities, likely to be involved in the development and progression of prostate cancer.

Cardiomyocyte-Specific Telomere Shortening is a Distinct Signature of Heart Failure in Humans

Background

Telomere defects are thought to play a role in cardiomyopathies, but the specific cell type affected by the disease in human hearts is not yet identified. The aim of this study was to systematically evaluate the cell type specificity of telomere shortening in patients with heart failure in relation to their cardiac disease, age, and sex.

Methods and Results

We studied cardiac tissues from patients with heart failure by utilizing telomere quantitative fluorescence in situ hybridization, a highly sensitive method with single‐cell resolution. In this study, total of 63 human left ventricular samples, including 37 diseased and 26 nonfailing donor hearts, were stained for telomeres in combination with cardiomyocyte‐ or α‐smooth muscle cell‐specific markers, cardiac troponin T, and smooth muscle actin, respectively, and assessed for telomere length. Patients with heart failure demonstrate shorter cardiomyocyte telomeres compared with nonfailing donors, which is specific only to cardiomyocytes within diseased human hearts and is associated with cardiomyocyte DNA damage. Our data further reveal that hypertrophic hearts with reduced ejection fraction exhibit the shortest telomeres. In contrast to other reported cell types, no difference in cardiomyocyte telomere length is evident with age. However, under the disease state, telomere attrition manifests in both young and older patients with cardiac hypertrophy. Finally, we demonstrate that cardiomyocyte‐telomere length is better sustained in women than men under diseased conditions.

Conclusions

This study provides the first evidence of cardiomyocyte‐specific telomere shortening in heart failure.

Telomeres and telomerase in prostate cancer development and therapy

Aberrations in telomere biology are among the earliest events in prostate cancer tumorigenesis and continue during tumour progression. Substantial telomere shortening occurs in prostate cancer cells and high-grade prostatic intraepithelial neoplasia. Not all mechanisms of telomere shortening are understood, but oxidative stress from local inflammation might accelerate prostatic telomere loss. Critically short telomeres can drive the accumulation of tumour-promoting genomic alterations; however, continued telomere erosion is unsustainable and must be mitigated to ensure cancer cell survival and unlimited replication potential. Prostate cancers predominantly maintain telomeres by activating telomerase, but alternative mechanisms of telomere extension can occur in metastatic disease. Telomerase activity and telomere length assessment might be useful in prostate cancer diagnosis and prognosis. Telomere shortening in normal stromal cells has been associated with prostate cancer, whereas variable telomere lengths in prostate cancer cells and telomere shortening in cancer-associated stromal cells correlated with lethal disease. Single-agent telomerase-targeted treatments for solid cancers were ineffective in clinical trials but have not been investigated in prostate cancer and might be useful in combination with established regimens. Telomere-directed strategies have not been explored as extensively. Telomere deprotection strategies have the advantage of being effective in both telomerase-dependent and telomerase-independent cancers. Disruption of androgen receptor function in prostate cancer cells results in telomere dysfunction, indicating telomeres and telomerase as potential therapeutic targets in prostate cancer.

Dihydrotestosterone: Biochemistry, Physiology, and Clinical Implications of Elevated Blood Levels

Benefits associated with lowered serum DHT levels after 5α-reductase inhibitor (5AR-I) therapy in men have contributed to a misconception that circulating DHT levels are an important stimulus for androgenic action in target tissues (e.g., prostate). Yet evidence from clinical studies indicates that intracellular concentrations of androgens (particularly in androgen-sensitive tissues) are essentially independent of circulating levels. To assess the clinical significance of modest elevations in serum DHT and the DHT/testosterone (T) ratio observed in response to common T replacement therapy, a comprehensive review of the published literature was performed to identify relevant data. Although the primary focus of this review is about DHT in men, we also provide a brief overview of DHT in women. The available published data are limited by the lack of large, well-controlled studies of long duration that are sufficiently powered to expose subtle safety signals. Nonetheless, the preponderance of available clinical data indicates that modest elevations in circulating levels of DHT in response to androgen therapy should not be of concern in clinical practice. Elevated DHT has not been associated with increased risk of prostate disease (e.g., cancer or benign hyperplasia) nor does it appear to have any systemic effects on cardiovascular disease safety parameters (including increased risk of polycythemia) beyond those commonly observed with available T preparations. Well-controlled, long-term studies of transdermal DHT preparations have failed to identify safety signals unique to markedly elevated circulating DHT concentrations or signals materially different from T.

Telomeres and telomerase in head and neck squamous cell carcinoma: from pathogenesis to clinical implications

Strongly associated with tobacco use, heavy alcohol consumption, and with high-risk human papillomavirus (HPV) infection, head and neck squamous cell carcinoma (HNSCC) is a frequently lethal, heterogeneous disease whose pathogenesis is a multistep and multifactorial process involving genetic and epigenetic events. The majority of HNSCC patients present with locoregional advanced stage disease and are treated with combined modality strategies that can markedly impair quality of life and elicit unpredictable results. A large fraction of those who undergo locoregional treatment and achieve a complete response later develop locoregional recurrences or second field tumors. Biomarkers that are thus able to stratify risk and enable clinicians to tailor treatment plans and to personalize post-therapeutic surveillance strategies are highly desirable. To date, only HPV status is considered a reliable independent predictor of treatment response and survival in patients with HNSCC arising from the oropharyngeal site. Recent studies suggest that telomere attrition, which may be an early event in human carcinogenesis, and telomerase activation, which is detected in up to 90 % of malignancies, could be potential markers of cancer risk and disease outcome. This review examines the current state of knowledge on and discusses the implications linked to telomere dysfunction and telomerase activation in the development and clinical outcome of HNSCC.

Circulating Prostate-Specific Antigen and Telomere Length in a Nationally Representative Sample of Men Without History of Prostate Cancer

BACKGROUND

We investigated the association of prostate-specific antigen (PSA) with leukocyte telomere length, which may be altered in preclinical prostate malignancies.

METHODS

This study was based on the 2001-2002 U.S. National Health and Nutrition Examination Survey (NHANES). A subsample of 1,127 men aged 40-85 years without prior history of prostate cancer who provided informed consent and blood samples were selected. Leukocyte telomere length (LTL) relative to standard DNA reference (T/S ratio) was quantified by polymerase chain reaction (PCR). Survey-weighted multivariable linear regression was performed to examine T/S ratio across quintiles of total and free PSA and free-to-total PSA ratio (%fPSA). A sensitivity analysis was performed by excluding men dying from prostate cancer during follow-up through to December 31, 2006. Stratification analyses were carried out to assess any effect modification by age group, race, body mass index (BMI), and levels of C-reactive protein (CRP), a marker of inflammation.

RESULTS

Higher total PSA levels were associated to longer LTL, with approximately 8% increase in log-transformed T/S ratio (95% confidence interval [CI]: 2-13%) among men in the highest quintile of total PSA compared to the lowest in the fully adjusted model (P_trend  = 0.01). No significant association was found for free PSA or %fPSA, although nonlinearity between all PSA measures and T/S ratio was indicated. Similar results were found after excluding men who died from prostate cancer during follow-up. We also found the associations between total PSA and T/S ratio to be strongest among non-Hispanic blacks, non-obese men (BMI <30 kg/m² ), and those with low CRP. However, a significant interaction was only found between total PSA and race/ethnicity (P_interaction  = 0.01).

CONCLUSION

Total PSA levels were strongly associated to LTL, particularly among non-Hispanic blacks. Our findings support a potential link between PSA and specific mechanisms contributing to prostate cancer development. Prostate 77:22-32, 2017. © 2016 Wiley Periodicals, Inc.

Dynamics of three-dimensional telomere profiles of circulating tumor cells in patients with high-risk prostate cancer who are undergoing androgen deprivation and radiation therapies

INTRODUCTION

Accurate assessment and monitoring of the therapeutic efficacy of locally advanced prostate cancer remains a major clinical challenge. Contrary to prostate biopsies, circulating tumor cells (CTCs) are a cellular source repeatedly obtainable by blood sampling and could serve as a surrogate marker for treatment efficacy. In this study, we used size-based filtration to isolate and enumerate CTCs from the blood of 20 patients with high-risk (any one of cT3, Gleason 8-10, or prostate-specific antigen>20ng/ml), nonmetastatic, and treatment-naive prostate cancer before and after androgen deprivation therapy (ADT) and radiation therapy (RT).

MATERIALS AND METHODS

We performed 3D telomere-specific quantitative fluorescence in situ hybridization on isolated CTCs to determine 3D telomere profiles for each patient before and throughout the course of both ADT and RT.

RESULTS

Based on the distinct 3D telomere signatures of CTC before treatment, patients were divided into 3 groups. ADT and RT resulted in distinct changes in 3D telomere signatures of CTCs, which were unique for each of the 3 patient groups.

CONCLUSION

The ability of 3D telomere analysis of CTCs to identify disease heterogeneity among a clinically homogeneous group of patients, which reveals differences in therapeutic responses, provides a new opportunity for better treatment monitoring and management of patients with high-risk prostate cancer.

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.