A study of the relationship between expression level of TRF1 protein and telomerase activity in human acute leukemia

Relative Leukocyte Telomere Length and Genetic Variants in Telomere-Related Genes and Serum Levels Role in Age-Related Macular Degeneration

Telomere shortening is well known to be associated with ageing. Age is the most decisive risk factor for age-related macular degeneration (AMD) development. The older the individual, the higher the AMD risk. For this reason, we aimed to find any associations between telomere length, distribution of genetic variants in telomere-related genes (TERT, TERT-CLPTM1, TRF1, TRF2, and TNKS2), and serum TERF-1 and TERF2 levels on AMD development.

METHODS

Our study enrolled 342 patients with AMD and 177 healthy controls. Samples of DNA from peripheral blood leukocytes were extracted by DNA salting-out method. The genotyping of TERT rs2736098, rs401681 in TERT-CLPTM1 locus, TRF1 rs1545827, rs10107605, TNKS2 rs10509637, rs10509639, and TRF2 rs251796 and relative leukocyte telomere length (T/S) measurement were carried out using the real-time polymerase chain reaction method. Serum TERF-1 and TERF2 levels were measured by enzymatic immunoassay (ELISA).

RESULTS

We found longer telomeres in early AMD patients compared to the control group. Additionally, we revealed that minor allele C at TRF1 rs10107605 was associated with decreases the odds of both early and exudative AMD. Each minor allele G at TRF2 rs251796 and TRF1 rs1545827 C/T genotype and C/T+T/T genotypes, compared to the C/C genotype, increases the odds of having shorter telomeres. Furthermore, we found elevated TERF1 serum levels in the early AMD group compared to the control group.

CONCLUSIONS

In conclusion, these results suggest that relative leukocyte telomere length and genetic variants of TRF1 and TRF2 play a role in AMD development. Additionally, TERF1 is likely to be associated with early AMD.

Identifying the biomarker potential of telomerase activity and shelterin complex molecule, telomeric repeat binding factor 2 (TERF2), in multiple myeloma

Telomere length (TL) is maintained by telomere capping protein complex called shelterin complex. We studied the possible involvement and biomarker potential of shelterin complex molecules in naive multiple myeloma (MM) patients and controls. TL, relative telomerase activity (RTA), real-time PCR and Western blotting were performed in bonemarrow sample of 70 study subjects (patients = 50; controls = 20). Significantly lowered mean TL, increased RTA and higher mRNA expression of shelterin molecules were observed in patients, while PIN2/TERF1 interacting telomerase inhibitor 1 (PINX1) showed lower mRNA expression. Significantly increased protein expression of telomeric repeat binding factor 2 (TERF2), protection of telomeres 1, adrenocortical dysplasia homolog, Tankyrase 1 and telomere reverse transcriptase were observed in MM patients. Significant correlation was observed among genes and of genes with clinical parameters. In conclusion, our findings showed alteration of these molecules at mRNA and protein levels suggested their involvement in disease progression. Optimal sensitivity and specificity of TERF2 and RTA on receiver operating characteristics curve analysis and univariate analysis demonstrated their biomarkers potential in better prediction of disease course.

The telomere proteins in tumorigenesis and clinical outcomes of oral squamous cell carcinoma

The "Hallmarks of Cancer" describe the ways by which cancer cells bypass homeostasis. Escape from replicative senescence is one of the earliest features of cancer cells. Maintenance of the telomeres through reactivation of telomerase was initially associated with replicative immortality in various cancers. The shelterin complex, a telomeric hexaprotein association, plays a key role in telomere maintenance and in the hallmarks of cancer. Some shelterin proteins are overexpressed in diverse cancers and can promote tumorigenesis in animal models. Shelterin can also have an impact on tumor size, tumor growth and resistance to treatment. Studies into the expression level of shelterin in oral squamous cell carcinoma (OSCC) report contradictory results. Moreover, the exact role of these proteins in OSCC tumorigenesis remains uncertain. In this review, we examined the data linking telomeres and hallmarks of OSCC. Furthermore, we examined the literature concerning telomeres and the clinical outcome of OSCC. Finally, we propose a model encompassing the role of shelterin proteins in oral tumorigenesis and treatment outcome.

The role of telomeres and telomerase in hematologic malignancies and hematopoietic stem cell transplantation

Telomeres are specific nucleoprotein structures at the ends of eukaryotic chromosomes. Telomeres and telomere-associated proteins maintain genome stability by protecting the ends of chromosomes from fusion and degradation. In normal somatic cells, the length of the telomeres gradually becomes shortened with cell division. In tumor cells, the shortening of telomeres length is accelerated under the increased proliferation pressure. However, it will be maintained at an extremely short length as the result of activation of telomerase. Significantly shortened telomeres, activation of telomerase, and altered expression of telomere-associated proteins are common features of various hematologic malignancies and are related with progression or chemotherapy resistance in these diseases. In patients who have received hematopoietic stem cell transplantation (HSCT), the telomere length and the telomerase activity of the engrafted donor cells have a significant influence on HSCT outcomes. Transplantation-related factors should be taken into consideration because of their impacts on telomere homeostasis. As activation of telomerase is widespread in tumor cells, it has been employed as a target point in the treatment of neoplastic hematologic disorders. In this review, the characteristics and roles of telomeres and telomerase both in hematologic malignancies and in HSCT will be summarized. The current status of telomerase-targeted therapies utilized in the treatment of hematologic malignancies will also be reviewed.