Telomere Length and Survival of Patients with Hepatocellular Carcinoma in the United States

The dynamics of telomere length in primary and metastatic colorectal cancer lesions

Telomeric sequences, the structures comprised of hexanucleotide repeats and associated proteins, play a pivotal role in chromosome end protection and preservation of genomic stability. Herein we address telomere length (TL) dynamics in primary colorectal cancer (CRC) tumour tissues and corresponding liver metastases. TL was measured by multiplex monochrome real-time qPCR in paired samples of primary tumours and liver metastases along with non-cancerous reference tissues obtained from 51 patients diagnosed with metastatic CRC. Telomere shortening was observed in the majority of primary tumour tissues compared to non-cancerous mucosa (84.1%, p < 0.0001). Tumours located within the proximal colon had shorter TL than those in the rectum (p < 0.05). TL in liver metastases was not significantly different from that in primary tumours (p = 0.41). TL in metastatic tissue was shorter in the patients diagnosed with metachronous liver metastases than in those diagnosed with synchronous liver metastases (p = 0.03). The metastatic liver lesions size correlated with the TL in metastases (p < 0.05). Following the neoadjuvant treatment, the patients with rectal cancer had shortened telomeres in tumour tissue than prior to the therapy (p = 0.01). Patients with a TL ratio between tumour tissue and the adjacent non-cancerous mucosa of ≥ 0.387 were associated with increased overall survival (p = 0.01). This study provides insights into TL dynamics during progression of the disease. The results show TL differences in metastatic lesions and may help in clinical practice to predict the patient's prognosis.

A standalone approach to utilize telomere length measurement as a surveillance tool in oral leukoplakia

Oral squamous cell carcinoma (OSCC) is often preceded by a white patch on a surface of the mouth, called oral leukoplakia (OL). As accelerated telomere length (TL) shortening in dividing epithelial cells may lead to oncogenic transformation, telomere length measurement could serve as a predictive biomarker in OL. However, due to high variability and lack of a universal reference, there has been a limited translational application. Here, we describe an approach of evaluating TL using paired peripheral blood mononuclear cells (PBMC) as an internal reference and demonstrate its translational relevance. Oral brush biopsy and paired venous blood were collected from 50 male OL patients and 44 male healthy controls (HC). Relative TL was measured by quantitative PCR. TL of each OL or healthy sample was normalized to the paired PBMC sample (TL ratio). In OL patients, the mean TL ratio was significantly smaller not only in the patch but also in distal normal oral tissue, relative to healthy controls without a high‐risk oral habit. Dysplasia was frequently associated with a subgroup that showed a normal TL ratio at the patch but significantly smaller TL ratio at a paired normal distal site. Our data suggest that evaluation of TL attrition using a paired PBMC sample eliminates the requirement of external reference DNA, makes data universally comparable and provides a useful marker to define high‐risk OL groups for follow‐up programs. Larger studies will further validate the approach and its broader application in other premalignant conditions.

Impact of aging on primary liver cancer: epidemiology, pathogenesis and therapeutics

Aging involves progressive physiological and metabolic reprogramming to adapt to gradual deterioration of organs and functions. This includes mechanisms of defense against pre-malignant transformations. Thus, certain tumors are more prone to appear in elderly patients. This is the case of the two most frequent types of primary liver cancer, i.e., hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (iCCA). Accordingly, aging hallmarks, such as genomic instability, telomere attrition, epigenetic alterations, altered proteostasis, mitochondrial dysfunction, cellular senescence, exhaustion of stem cell niches, impaired intracellular communication, and deregulated nutrient sensing can play an important role in liver carcinogenesis in the elders. In addition, increased liver fragility determines a worse response to risk factors, which more frequently affect the aged population. This, together with the difficulty to carry out an early detection of HCC and iCCA, accounts for the late diagnosis of these tumors, which usually occurs in patients with approximately 60 and 70 years, respectively. Furthermore, there has been a considerable controversy on what treatment should be used in the management of HCC and iCCA in elderly patients. The consensus reached by numerous studies that have investigated the feasibility and safety of different curative and palliative therapeutic approaches in elders with liver tumors is that advanced age itself is not a contraindication for specific treatments, although the frequent presence of comorbidities in these individuals should be taken into consideration for their management.

The role of telomeres and telomerase in cirrhosis and liver cancer

Telomerase is a key enzyme for cell survival that prevents telomere shortening and the subsequent cellular senescence that is observed after many rounds of cell division. In contrast, inactivation of telomerase is observed in most cells of the adult liver. Absence of telomerase activity and shortening of telomeres has been implicated in hepatocyte senescence and the development of cirrhosis, a chronic liver disease that can lead to hepatocellular carcinoma (HCC) development. During hepatocarcinogenesis, telomerase reactivation is required to enable the uncontrolled cell proliferation that leads to malignant transformation and HCC development. Part of the telomerase complex, telomerase reverse transcriptase, is encoded by TERT, and several mechanisms of telomerase reactivation have been described in HCC that include somatic TERT promoter mutations, TERT amplification, TERT translocation and viral insertion into the TERT gene. An understanding of the role of telomeres and telomerase in HCC development is important to develop future targeted therapies and improve survival of this disease. In this Review, the roles of telomeres and telomerase in liver carcinogenesis are discussed, in addition to their potential translation to clinical practice as biomarkers and therapeutic targets.

Relative telomere length and oxidative stress in musculoskeletal tumors

Telomeres are capped at the end of the chromosome and gradually shorten when the cell divides. When there is an oxidative stress, it can cause the DNA to be damaged. Hence, 8-hydroxy-2'-deoxyguanosine (8-OHdG) has been shown to be an indicator for oxidative DNA damage. This study aimed to determine the relative telomere length (RTL) and 8-OHdG levels in neoplastic tissues, adjacent non-neoplastic tissues, and blood leukocytes of musculoskeletal (MS) tumor patients. Neoplastic tissues were compared to adjacent non-neoplastic tissues in MS tumor patients (n = 46). Peripheral blood leukocytes (PBLs) of MS tumor subjects were compared to those of age-matched healthy controls (n = 107). RTL was evaluated by quantitative real-time polymerase chain reaction and 8-OHdG levels were quantified by enzyme-linked immunosorbent assay. The RTL in neoplastic tissues was significantly shorter than that in non-neoplastic tissues [1.12 (0.86-1.46) vs 1.45 (1.25-1.65), P = 0.001]. PBLs had lower RTL than non-neoplastic tissues in MS tumor patients [1.04 (0.85-1.13) vs 1.45 (1.25-1.65), P < 0.001]. However, there was no significant difference between RTL in PBLs and in neoplastic tissues. In addition, PBLs of MS tumor patients had higher RTL than those of the controls [1.04 (0.85-1.13) versus 0.78 (0.68-0.90), P < 0.001]. The 8-OHdG levels in neoplastic tissues were remarkably higher than those in non-neoplastic tissues [8.14 (6.81-11.37) nM/μg/μl vs. 3.79 (2.53-6.17) nM/μg/μl, P < 0.001]. Furthermore, plasma 8-OHdG levels in MS tumor patients were markedly greater than those in the controls [102.50 (73.16-133.50) nM vs. 41.09 (6.81-11.37) nM, P < 0.001]. Area under the curve (AUC) was 0.7536 (95% confident interval (CI) 0.6602-0.8469) when the cut-off value of RTL in PBLs was 0.97. Also, plasma 8-OHdG levels depicted that when the cut-off value was 38.67 nM, the AUC was 0.7723 (95% CI 0.6920-0.8527). Moreover, ROC curve analysis showed that both RTL and 8-OHdG appeared to improve the sensitivity (85.68%) and specificity (70.91%) with the AUC 0.8639 (95% CI 0.7500-0.9500). This study suggested that blood leukocyte RTL and plasma 8-OHdG could serve as promising non-invasive biomarkers to differentiate between MS tumor patients and healthy controls. Additionally, telomere attrition and increased oxidative DNA damage might play contributory roles in the pathogenesis of MS tumors.

Influence of donor liver telomere and G-tail on clinical outcome after living donor liver transplantation

It has been reported that donor age affects patient outcomes after liver transplantation, and that telomere length is associated with age. However, to our knowledge, the impact of donor age and donor liver telomere length in liver transplantation has not been well investigated. This study aimed to clarify the influence of the length of telomere and G-tail from donor livers on the outcomes of living donors and recipients after living donor liver transplantation. The length of telomere and G-tail derived from blood samples and liver tissues of 55 living donors, measured using the hybridization protection assay. The length of telomeres from blood samples was inversely correlated with ages, whereas G-tail length from blood samples and telomere and G-tail lengths from liver tissues were not correlated with ages. Age, telomere, and G-tail length from blood did not affect postoperative liver failure and early liver regeneration of donors. On the other hand, the longer the liver telomere, the poorer the liver regeneration tended to be, especially with significant difference in donor who underwent right hemihepatectomy. We found that the survival rate of recipients who received liver graft with longer telomeres was inferior to that of those who received liver graft with shorter ones. An elderly donor, longer liver telomere, and higher Model for End-Stage Liver Disease score were identified as independent risk factors for recipient survival after transplantation. In conclusion, telomere shortening in healthy liver does not correlate with age, whereas longer liver telomeres negatively influence donor liver regeneration and recipient survival after living donor liver transplantation. These results can direct future studies and investigations on telomere shortening in the clinical and experimental transplant setting.

Telomere Length and Lung Cancer Mortality among Heavy Smokers

Background: Accumulating evidence suggests that short telomere length is associated with increased overall mortality, but the relationship with cancer mortality is less clear. We examined whether telomere length (global, and chromosome arm 5p- and 13q-specific) is associated with lung cancer mortality among cases from the β-Carotene and Retinol Efficacy Trial of heavy smokers.Methods: Telomere length was measured on average 6 years before diagnosis for 788 lung cancer cases. Adjusted Cox proportional hazards models of all-cause and lung cancer-specific mortality were assessed for lung cancer overall and by histotype.Results: Short telomere length was associated with increased mortality for small cell lung cancer (SCLC), particularly stage III/IV SCLC [HR and 95% confidence interval for shortest vs. longest telomere length tertile: 3.32 (1.78-6.21)]. Associations were strongest for those randomized to the active intervention and when telomere length was measured ≤5 years before diagnosis. All-cause mortality patterns were similar. Short chromosome 5p telomere length was suggestively associated with lung cancer mortality, but there was no association with chromosome 13q telomere length.Conclusions: Our large prospective study suggests that among heavy smokers who developed lung cancer, short prediagnosis telomere length is associated with increased risk of death from SCLC.Impact: This is the first study to examine telomere length and mortality in lung cancer cases by histotype. If the association between short telomere length and SCLC mortality is replicated, elucidation of mechanisms through which telomere length influences survival for this highly aggressive cancer may inform more effective use of telomere-targeted therapeutics. Cancer Epidemiol Biomarkers Prev; 27(7); 829-37. ©2018 AACR.

Telomere length variation in tumor cells and cancer-associated fibroblasts: potential biomarker for hepatocellular carcinoma

The role of telomere dysfunction and aberrant telomerase activities in hepatocellular carcinoma (HCC) has been overlooked for many years. This study aimed to delineate the variation and prognostic value of telomere length in HCC. Telomere‐specific fluorescence in situ hybridization (FISH) and qPCR were used to evaluate telomere length in HCC cell lines, tumor tissues, and isolated non‐tumor cells within the tumor. Significant telomere attrition was found in tumor cells and cancer‐associated fibroblasts (CAFs) compared to their normal counterparts, but not in intratumor leukocytes or bile duct epithelial cells. Clinical relevance and prognostic value of telomere length were investigated on tissue microarrays of 257 surgically treated HCC patients. Reduced intensity of telomere signals in tumor cells or CAFs correlated with larger tumor size and the presence of vascular invasion (p < 0.05). Shortened telomeres in tumor cells or CAFs associated with reduced survival and increased recurrence, and were identified as independent prognosticators for HCC patients (p < 0.05). These findings were validated in an independent HCC cohort of 371 HCC patients from The Cancer Genome Atlas (TCGA) database, confirming telomere attrition and its prognostic value in HCC. We also showed that telomerase reverse transcriptase promoter (TERTp) mutation correlated with telomere shortening in HCC. Telomere variation in tumor cells and non‐tumor cells within the tumor microenvironment of HCC was a valuable prognostic biomarker for this fatal malignancy. © 2017 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.