Telomerase was first described by Greider and Blackburn in 1984, a discovery ultimately recognized by the Nobel Prize committee in 2009. The three decades following on from its discovery have been accompanied by an increased understanding of the fundamental mechanisms of telomerase activity, and its role in telomere biology. Telomerase has a clearly defined role in telomere length maintenance and an established influence on DNA replication, differentiation, survival, development, apoptosis, tumorigenesis, and a further role in therapeutic resistance in human stem and cancer cells including those of breast and cervical origin. TERT encodes the catalytic subunit and rate-limiting factor for telomerase enzyme activity. The mechanisms of activation or silencing of TERT remain open to debate across somatic, cancer, and stem cells. Promoter mutations upstream of TERT may promote dysregulated telomerase activation in tumour cells but additional factors including epigenetic, transcriptional and posttranscriptional modifications also have a role to play. Previous systematic analysis indicated methylation and mutation of the TERT promoter in 53% and 31%, respectively, of TERT expressing cancer cell lines supporting the concept of a key role for epigenetic alteration associated with TERT dysregulation and cellular transformation. Epigenetic regulators including DNA methylation, histone modification, and non-coding RNAs are now emerging as drivers in the regulation of telomeres and telomerase activity. Epigenetic regulation may be responsible for reversible silencing of TERT in several biological processes including development and differentiation, and increased TERT expression in cancers. Understanding the epigenetic mechanisms behind telomerase regulation holds important prospects for cancer treatment, diagnosis and prognosis. This review will focus on the role of epigenetics in telomerase regulation.
This is an open, prospective, comparative parallel-arm medical device clinical study of Dermalix (Dx) in diabetic foot wounds. Dx is a 3-dimensional collagen-laminin porous-structured dermal matrix prepared and additionally impregnated with resveratrol-loaded hyaluronic acid and dipalmitoylphosphatidylcholine-based microparticles. The aim was to evaluate the efficacy and safety of Dx, an investigational medical device, in Wagner 1 and 2 wounds in comparison to a standard wound care (SWC) that consists of irrigation and cleaning with sterile saline solution. Forty-eight patients were randomized to receive either SWC or SWC + Dx. A 4-week treatment period was followed by a 2-month follow-up without treatment. The wound area measurement, total collagen, vascular epidermal growth factor, tumor necrosis factor, interleukin 1, caspase 3, glutathione, reduced/oxidized glutathione, and lipid peroxidation levels were evaluated. At the end of 4 weeks, the percentage closures of wounds were determined as 57.82% for Dx, and 26.63% for SWC groups. Dx had a significant effect on tumor necrosis factor, caspase 3, and reduced/oxidized glutathione levels. Dx provided 2 times faster wound healing and decreased oxidative stress. Application of Dx in the first phase of wound would help the wound area heal faster with a safe profile.
It is emphasized that cancer stem cells (CSCs) forming the subpopulation of tumour cells are responsible for tumour growth, metastasis, and cancer drug resistance. Inadequate response to conventional therapy in breast cancer leads researchers to find new treatment methods and literature surveys that support CSC studies. A selective anticancer agent BIBR1532 inhibits the telomerase enzyme. Many of the chemotherapeutic drugs used in clinical trials have harmful effects, but the advantage of telomerase‐based inhibitors is that they are less toxic to healthy tissues. The phosphoinositide 3‐kinase (PI3K)/serine/threonine kinase (Akt)/mammalian target of rapamycin (mTOR) pathway is common in breast cancer, and the interaction between the mTOR pathway and human telomerase reverse transcriptase (hTERT) is essential for the survival of cancer cells. In our study, we treated MCF‐7, breast cancer stem cell (BCSC) and normal breast epithelial cell MCF10A with the BIBR1532 inhibitor. The IC 50 doses for the 48th hour of BIBR1532 treatment were detected as 34.59 μM in MCF‐7, 29.91 μM in BCSCs, and 29.07 μM in MCF10A. It has been observed that this agent induces apoptosis in the BCSC and MCF‐7 cell lines. According to the results of cell cycle analysis, G 2/M phase accumulation was observed in BCSC and MCF‐7 cell lines. It has also been shown that BIBR1532 suppresses telomerase activity in BCSC and MCF‐7. The effect of BIBR1532 on the mTOR signalling pathway has been investigated for the first time in this study. It is thought that the telomerase inhibitor may bring a new approach to the treatment and it may be useful in the treatment of CSCs.
The application of physiological oxygen (physoxia) concentrations is becoming increasingly commonplace within a mammalian stem cell culture. Human mesenchymal stem cells (hMSCs) attract widespread interest for clinical application due to their unique immunomodulatory, multi-lineage potential, and regenerative capacities. Descriptions of the impact of physoxia on global DNA methylation patterns in hMSCs and the activity of enzymatic machinery responsible for its regulation remain limited. Human bone marrow-derived mesenchymal stem cells (BM-hMSCs, passage 1) isolated in reduced oxygen conditions displayed an upregulation of SOX2 in reduced oxygen conditions vs. air oxygen (21% O2, AO), while no change was noted for either OCT-4 or NANOG. DNA methylation marks 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC) showed decreases in 2% O2 environment (workstation) (2% WKS). DNMT3B (DNA methyltransferase 3B) and TET1 (Ten-eleven translocation enzyme 1) displayed reduced transcription in physoxia. Consistent with transcriptional downregulation, we noted increased promoter methylation levels of DNMT3B in 2% WKS accompanied by reduced DNMT3B and TET1 protein expression. Finally, a decrease in HIF1A (Hypoxia-inducible factor 1A) gene expression in 2% WKS environment correlated with protein levels, while HIF2A was significantly higher in physoxia correlated with protein expression levels vs. AO. Together, these data have demonstrated, for the first time, that global 5mC, 5hmC, and DNMT3B are oxygen-sensitive in hMSCs. Further insights into the appropriate epigenetic regulation within hMSCs may enable increased safety and efficacy development within the therapeutic ambitions.
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