Telomerase activity in sputum and telomerase and its components in biopsies of advanced lung cancer

Template-ready PCR method for detection of human telomerase reverse transcriptase mRNA in sputum

Human telomerase reverse transcriptase (hTERT) mRNA in tissue is a biomarker of lung cancer, but hTERT mRNA in sputum had not been successfully detected with conventional reverse transcription PCR methods. Here, we developed a novel PCR protocol: Template-Ready PCR (TRPCR), to detect sputum hTERT mRNA, in which probes serve as templates of amplification. While free probes and dsDNA were removed in template preparation through aspiration and restriction digestion, probes that formed into heterocomplex with target RNA remained intact for PCR amplification. By fishing out the heterocomplex and amplifying the probes, TRPCR achieved sensitivity higher than reverse transcription-quantitative PCR (RT-qPCR). ROC curve of sputum hTERT mRNA by TRPCR assay showed the discrimination in high sensitivity and specificity between patients with lung cancer and lung cancer-free donors at the PCR Ct cutoff of 33. We further validated this approach through TRPCR assay of sputum from 858 lung cancer patients and 480 non-malignant pulmonary disease patients. 722 (84.2%) cases from 858 with lung cancer patients were detected as positive, whereas 461 (96.0%) cases from 480 non-malignant pulmonary disease patients were detected as negative, suggesting that TRPCR assay of sputum hTERT mRNA can serve as a non-invasive molecular diagnosis of lung cancer.

Telomerase activity in non-small cell lung cancer

INTRODUCTION

High telomerase activity has been detected in the majority of malignant neoplasms including lung cancer. The purpose of the study was to attempt to use telomerase activity as a prognostic factor in patients with non-small cell lung cancer (NSCLC).

MATERIAL AND METHODS

Telomerase activity was analyzed in 47 tissue specimens taken from patients with NSCLC. The control group consisted of 30 specimens of non-cancerous lung parenchyma. Telomerase activity was measured by means of the telomeric repeat amplification protocol (TRAP).

RESULTS

Telomerase activity in the neoplastic tissue was significantly higher than in the lung parenchyma that was free from neoplastic infiltration. There was no significant association between telomerase activity and age, gender, tobacco smoking, histological type of the tumor, or staging (pTNM). No association was found between the level of telomerase activity in NSCLC specimens and the two-year survival rate of patients (p = 0.326). A higher level of telomerase activity in poorly differentiated tumors (G3) as compared to moderately differentiated tumors (G2) was detected (p = 0.008). A positive association was identified between telomerase activity in pulmonary parenchyma free from tumor infiltration and the presence of leukocyte infiltration (p = 0.0001).

CONCLUSIONS

No association was found between the level of telomerase activity in NSCLC specimens and the two-year survival rate of patients. The study has revealed a positive association between telomerase activity and the grade of differentiation (G) in NSCLC.

Usage patterns of biomarkers in non-small-cell lung cancer patients in India: Findings from a systematic review and survey

INTRODUCTION

Personalized medicine has facilitated improved management of non-small cell lung cancer (NSCLC) patients by identifying predictive and prognostic biomarkers for enhanced efficiency of detection and efficacy of treatment. This systematic review and survey assessed the patterns of biomarker usage, molecular testing techniques to diagnose patients with NSCLC in India and testing techniques recommended by cancer societies.

MATERIALS AND METHODS

Studies were retrieved from Embase, PubMed, and Cochrane databases for the last 12 years, using relevant search strategies as per the Cochrane methodology for systematic reviews. Outcomes of interest were biomarkers for NSCLC, patterns of biomarker testing, diagnostic methods, guidelines and cost of biomarker testing.

RESULTS

In all, 499 studies were identified for screening and 17 primary publications were included in the review. Epidermal growth factor receptor (EGFR) expression and epithelial markers (particularly cytokeratins (CK)) were the most commonly reported biomarkers (7/17) and immunohistochemical (IHC) staining was the most common technique for detection of biomarkers. The frequency of EGFR mutations was higher among women than men. Significantly elevated levels of CK-18 were observed in patients with squamous cell carcinoma and of CK-19 in patients with adenocarcinoma, squamous cell carcinoma, and NSCLC (P < 0.001). Prognostic or predictive role of cytokines and angiogenic markers as well as DNA expression were evaluated. The survey also showed that IHC was the most common technique for detection of biomarkers.

CONCLUSIONS

This systematic review and survey provides valuable information on biomarker usage in the Indian population, and highlights the need for initiatives required for future biomarker testing in India.

Epidemiology of lung cancer: Diagnosis and management of lung cancer, 3rd ed: American College of Chest Physicians evidence-based clinical practice guidelines

BACKGROUND

Ever since a lung cancer epidemic emerged in the mid-1900 s, the epidemiology of lung cancer has been intensively investigated to characterize its causes and patterns of occurrence. This report summarizes the key findings of this research.

METHODS

A detailed literature search provided the basis for a narrative review, identifying and summarizing key reports on population patterns and factors that affect lung cancer risk.

RESULTS

Established environmental risk factors for lung cancer include smoking cigarettes and other tobacco products and exposure to secondhand tobacco smoke, occupational lung carcinogens, radiation, and indoor and outdoor air pollution. Cigarette smoking is the predominant cause of lung cancer and the leading worldwide cause of cancer death. Smoking prevalence in developing nations has increased, starting new lung cancer epidemics in these nations. A positive family history and acquired lung disease are examples of host factors that are clinically useful risk indicators. Risk prediction models based on lung cancer risk factors have been developed, but further refinement is needed to provide clinically useful risk stratification. Promising biomarkers of lung cancer risk and early detection have been identified, but none are ready for broad clinical application.

CONCLUSIONS

Almost all lung cancer deaths are caused by cigarette smoking, underscoring the need for ongoing efforts at tobacco control throughout the world. Further research is needed into the reasons underlying lung cancer disparities, the causes of lung cancer in never smokers, the potential role of HIV in lung carcinogenesis, and the development of biomarkers.

Molecular sputum analysis for the diagnosis of lung cancer

Lung cancer is the leading cause of cancer mortality rate worldwide, mainly because of the presence of metastatic disease at the time of diagnosis. Early detection of lung cancer improves prognosis, and towards this end, large screening trials in high-risk individuals have been conducted since the past century. Despite all efforts, the need for novel (complementary) lung cancer diagnostic and screening methods still exists. In this review, we focus on the assessment of lung cancer-related biomarkers in sputum in the past decennium. Besides cytology, mutation and microRNA analysis, special attention has been paid to DNA promoter hypermethylation, of which all available literature is summarised without time restriction. A model is proposed to aid in the distinction between diagnostic and risk markers. Research on the use of sputum for non-invasive detection of early-stage lung cancer has brought new insights and advanced molecular techniques. The sputum shows a promising potential for routine diagnostic and possibly screening purposes.

Prevalence of telomerase activity in human cancer

Telomerase activity has been measured in a wide variety of cancerous and non-cancerous tissue types, and the vast majority of clinical studies have shown a direct correlation between it and the presence of cancerous cells. Telomerase plays a key role in cellular immortality and tumorigenesis. Telomerase is activated in 80-90% of human carcinomas, but not in normal somatic cells, therefore, its detection holds promise as a diagnostic marker for cancer. Measurable levels of telomerase have been detected in malignant cells from various samples: tissue from gestational trophoblastic neoplasms; squamous carcinoma cells from oral rinses; lung carcinoma cells from bronchial washings; colorectal carcinoma cells from colonic luminal washings; bladder carcinoma cells from urine or bladder washings; and breast carcinoma or thyroid cancer cells from fine needle aspirations. Such clinical tests for telomerase can be useful as non-invasive and cost-effective methods for early detection and monitoring of cancer. In addition, telomerase activity has been shown to correlate with poor clinical outcome in late-stage diseases such as non-small cell lung cancer, colorectal cancer, and soft tissue sarcomas. In such cases, testing for telomerase activity can be used to identify patients with a poor prognosis and to select those who might benefit from adjuvant treatment. Our review of the latest medical advances in this field reveals that telomerase holds great promise as a biomarker for early cancer detection and monitoring, and has considerable potential as the basis for developing new anticancer therapies.

Amplification of the telomerase RNA component gene in the process of human esophageal carcinogenesis

Amplification of the human telomerase RNA component (hTERC) gene occurs early in cervical cancer development. Telomerase, the product of the hTERC gene, plays an important role in tumor cell apoptosis and genomic stability. Given the numerous similarities between esophageal and cervical cancers, we hypothesized that hTERC gene amplification may also be related with esophageal cancer development. We therefore examined 189 tissue sections from 63 cases of esophageal cancer and preneoplastic lesions. hTERC gene amplification in the lesions was detected by interphase fluorescence in situ hybridization. Of the 189 tissue sections, 149 were successfully evaluated (40 samples were excluded because of inappropriately preparation) and were classified as normal (n=45), atypical hyperplasia I (n=27), atypical hyperplasia II/III (n=22), and squamous cell carcinomas (SCCs; the most common type of esophageal cancer) (n=55). hTERC gene expression was not detected in normal esophageal tissue, whereas its expression was detected in atypical hyperplasias I (25.9%), atypical hyperplasia II/III (54.5%), and SCCs (90.9%) (p<0.05). The average copy numbers of hTERC in atypical hyperplasias I and II/III, as well as SCCs were 2.19, 2.35, and 2.64, respectively. In particular, the numbers of abnormal nuclei in atypical hyperplasias II/III were significantly higher than those of in atypical hyperplasia I (p<0.05). The hTERC gene amplification was not related with patient gender, histological stage, lymph nodes metastasis, and SCC differentiation grade (p>0.05). All these findings suggest that hTERC gene amplification is associated with SCC development.