How will telomeric complex be further contributed to our longevity? - the potential novel biomarkers of telomere complex counteracting both aging and cancer

The TERT rs2736100 Polymorphism and Susceptibility to Myeloproliferative Neoplasms: A Systematic Review and Meta-Analysis

Introduction: The classification of myeloproliferative neoplasms (MPN) is currently based on the genotype. Thus, to achieve better diagnostic and prognostic outcomes, it is necessary to further investigate the genetic spectrum underlying the pathogenesis of MPNs. The rs2736100A>C is a functional single nucleotide polymorphism in the telomerase reverse transcriptase (TERT) gene that has been previously reported to be associated with the risk of MPNs. Herein, we performed a meta-analysis to confirm the relationship between the TERT rs2736100A>C polymorphism and MPN susceptibility. Materials and Methods: Studies of case-control design were acquired from online databases with specific inclusion criteria. Odds ratios (ORs) with 95% confidence intervals (95% CI) were estimated to evaluate the association between the TERT rs2736100 polymorphism and MPN susceptibility using different genetic models. Results: Ten case-control studies involving 3488 cases and 57,948 controls were examined. Overall, there was a significant association between the TERT rs2736100 polymorphism and the risk of MPNs (allele model [C vs. A]: OR = 1.57 [95% CI: 1.47-1.69]; homozygous model [CC vs. AA]: OR = 3.00 [95% CI: 2.40-3.76]; heterozygous model [AC vs. AA]: OR = 2.17 [95% CI: 1.77-2.66]; dominant model [CC+AC vs. AA]: OR = 2.43 [95% CI: 2.00-2.95]; and recessive model [CC vs. AC+AA]: OR = 1.73 [95% CI: 1.47-2.04]). Conclusions: In this meta-analysis, we confirm an association between the TERT rs2736100A>C polymorphism and MPN susceptibility under all genetic models evaluated. The TERT rs2736100A>C allele increases the overall risk of MPN. Further studies are warranted to determine the functional role of the TERT rs2736100 polymorphism in MPN.

Genotoxicity of the vegetables juice grown in garden built on the tailings coal deposits

The aim of the present study was to evaluate the genotoxic effect of lettuce (Lactuca sativa L.), beet (Beta vulgaris L.), broccoli (Brassica oleracea var. italica), and kale (Brassica oleracea var. acephala) grown in vegetable garden built on the deposits of coal tailings. For this, we used 72 healthy male Swiss albino mice that received juice from the vegetables in an acute or chronic treatment. Using comet assay, we determined that acute administration of the juices of all vegetables from the coal-mining area was genotoxic, and increased the DNA damage in the blood, liver, and cerebral cortex of mice. Therefore, the present data suggest that intake of vegetables cultivated over coal waste results in an increase in DNA damage in some organs; this situation may pose a risk to health.

Integrated analysis of promoter methylation and expression of telomere related genes in breast cancer

Telomeres at the ends of eukaryotic chromosomes play a critical role in tumorgenesis. Using microfluidic PCR and next-generation bisulfite sequencing technology, we investigated the promoter methylation of 29 telomere related genes in paired tumor and normal tissues from 184 breast cancer patients. The expression of significantly differentially methylated genes was quantified using qPCR method.We observed that the average methylation level of the 29 telomere related genes was significant higher in tumor than that in normal tissues (P = 4.30E-21). A total of 4 genes (RAD50, RTEL, TERC and TRF1) showed significant hyper-methylation in breast tumor tissues. RAD51D showed significant methylation difference among the four breast cancer subtypes. The methylation of TERC showed significant association with ER status of breast cancer. The expression profiles of the 4 hyper-methylated genes showed significantly reduced expression in tumor tissues. The integration analysis of methylation and expression of these 4 genes showed a good performance in breast cancer prediction (AUC = 0.947).Our results revealed the methylation pattern of telomere related genes in breast cancer and suggested a novel 4-gene panel might be a valuable biomarker for breast cancer diagnosis.

The effect of chemotherapeutic agents on telomere length maintenance in breast cancer cell lines

Mammalian telomeric DNA consists of tandem repeats of the sequence TTAGGG associated with a specialized set of proteins, known collectively as Shelterin. These telosomal proteins protect the ends of chromosomes against end-to-end fusion and degradation. Short telomeres in breast cancer cells confer telomere dysfunction and this can be related to Shelterin proteins and their level of expression in breast cancer cell lines. This study investigates whether expression of Shelterin and Shelterin-associated proteins are altered, and influence the protection and maintenance of telomeres, in breast cancer cells. 5-aza-2′-deoxycytidine (5-aza-CdR) and trichostatin A (TSA) were used in an attempt to reactivate the expression of silenced genes. Our studies have shown that Shelterin and Shelterin-associated genes were down-regulated in breast cancer cell lines; this may be due to epigenetic modification of DNA as the promoter region of POT1 was found to be partially methylated. Shelterin genes expression was up-regulated upon treatment of 21NT breast cancer cells with 5-aza-CdR and TSA. The telomere length of treated 21NT cells was measured by q-PCR showed an increase in telomere length at different time points. Our studies have shown that down-regulation of Shelterin genes is partially due to methylation in some epithelial breast cancer cell lines. Removal of epigenetic silencing results in up-regulation of Shelterin and Shelterin-associated genes which can then lead to telomere length elongation and stability.

TERT promoter mutations in cancer development

Human telomerase reverse transcriptase (TERT) encodes a rate-limiting catalytic subunit of telomerase that maintains genomic integrity. TERT expression is mostly repressed in somatic cells with exception of proliferative cells in self-renewing tissues and cancer. Immortality associated with cancer cells has been attributed to telomerase over-expression. The precise mechanism behind the TERT activation in cancers has mostly remained unknown. The newly described germline and recurrent somatic mutations in melanoma and other cancers in the TERT promoter that create de novo E-twenty six/ternary complex factors (Ets/TCF) binding sites, provide an insight into the possible cause of tumor-specific increased TERT expression. In this review we discuss the discovery and possible implications of the TERT promoter mutations in melanoma and other cancers.