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The Scientific Basis of Medicine
Published in John S. Axford, Chris A. O'Callaghan, Medicine for Finals and Beyond, 2023
Chris O'Callaghan, Rachel Allen
To neutralize the tendency of chromosomes to shorten with each round of DNA replication, the telomerase enzyme elongates the ends of each chromosome to form a blocked telomere structure. Telomerase is usually active in stem cells and germ cells or during oncogenesis, but is not found in healthy somatic tissues. Modulation of telomerase enzyme has therefore become a subject of interest for anti-ageing and anticancer research.
Plant-Based Phytochemicals in the Prevention of Colorectal Cancer
Published in Megh R. Goyal, Preeti Birwal, Durgesh Nandini Chauhan, Herbs, Spices, and Medicinal Plants for Human Gastrointestinal Disorders, 2023
The plant, R. canina (Fig. 3.2, known commonly as Rosehip or Dog-Rose), is shown to have cytotoxic characteristics and has been used in specific treatments in medicine. This plant was experimentally tested against colon cancer and non-cancerous colon cells to see its cytotoxic activity. The results showed that there was a reduction of cell viability and an increase in the number of cells in early apoptosis when compared to the untreated cell lines while showing some selective cytotoxic activity. The active compounds in R. canina with antioxidative properties are Vitamin C and flavonoids and with cytotoxic characteristic is polyphenols.16,35,36 The results of this experiment showed that R. canina can arrest the colon cancer cells in the S-phase of cell division and also showed that R. canina increased the death rate of cancer cell via mitochondrial-dependent apoptosis. It can affect telomerase in cancer cells to reduce its expression, which can lead to an increase in cell death and antiproliferation.16,35,36
The science of ageing
Published in Michael Parker, Charlie James, Fundamentals for Cosmetic Practice, 2022
In certain cell lines (such as germ cells and stem cells), telomere length can be maintained by the function of the enzyme telomerase. Unlike DNA polymerase, telomerase can add repeating nucleotide sequences to the end of the telomere to mitigate the loss of length incurred by cell division. Telomerase is not produced within somatic cell lines, and therefore, its absence is contributory to the ageing process via replicative senescence.
Inhibition of Posterior Capsule Opacification by Adenovirus-Mediated Delivery of Short Hairpin RNAs Targeting TERT in a Rabbit Model
Published in Current Eye Research, 2023
Na He, Xiangxiang Zhang, Peiling Xie, Jialing He, Zhigang Lv
Prior studies have shown that telomerase activity in LECs with cataracts or PCO is significantly higher than that in normal LECs.13,20 Our previous study indicated that telomerase activity in the central LEC of PCO in rabbits was significantly lower than that in the equatorial region of the capsule bag.15 Telomerase can maintain telomerase length and prevent cell senescence.21 Telomerase activity is found in germinal and stem cells and most cancers but not in ocular tissues except LECs.11,12 TERT is the catalytic subunit of telomerase, and its transcription in LECs correlates with telomerase activity.22 In response to traumatic injury, ultraviolet light, and other oxidative stressors, TERT can be translocated from the cytoplasm to the nucleus to increase telomerase activity, resulting in DNA repair and proliferation.22,23 This may explain the increase in telomerase activity in PCO following cataract surgery as a response to injury.20 Therefore, we hypothesized that TERT silencing in LECs after cataract surgery may reduce PCO formation by decreasing telomerase activity. Since no telomerase activity was found in corneal epithelial and endothelial cells, lens fiber cells, or the retinal pigment epithelium, we hypothesized that this strategy may not cause toxic effects on other ocular tissues.
Severe immunochemotherapy-induced toxicities in a patient with dyskeratosis congenita and literature review
Published in Hematology, 2022
Jiayi Geng, Menglin Zhao, Qiuyu Li
Patients with telomere and/or telomerase dysfunction have a significantly increased risk of developing cancer[4]. Head and neck squamous cell carcinoma, acute myeloid leukemia, NHL and anal squamous cell carcinoma are the most common cancer types in DC patients, and these patients are reported to develop cancer at a younger age[4,11]. DC patients who accept chemotherapy or radiation therapy are thought to be predisposed to severe adverse effects due to impaired telomere and/or telomerase biology. For example, a study revealed that a shorter telomere length is associated with prolonged and severe neutropenia after chemotherapy[5], and anecdotal evidence suggests that chemotherapy may increase the risk for pulmonary and hepatic toxicities[6]. We searched the PubMed, Scopus, Medline, CNKI and Wanfang databases for related cases. However, very limited cases were found, and they are reviewed in Table 1.
Implications of TERT promoter mutations and telomerase activity in solid tumors with a focus on genitourinary cancers
Published in Expert Review of Molecular Diagnostics, 2022
Paola Valeria Marchese, Veronica Mollica, Elisa Tassinari, Dario De Biase, Francesca Giunchi, Andrea Marchetti, Matteo Rosellini, Michelangelo Fiorentino, Francesco Massari
It has been observed that unlike intestinal stem cells or the hematopoietic system, human normal basal bladder cells do not have constitutive telomerase activity [36]. It would appear that human normal basal bladder cells are capable of transiently upregulating telomerase expression in response to regenerative signals [37]. The implications of these data in the context of UC require further clarification. It has therefore been suggested that telomerase reactivation is the first mutation that initiates tumorigenesis in the urothelium in cells that have been activated for proliferation. Telomerase activity could therefore facilitate the survival of cells that developed secondary mutations, preventing entry into cellular senescence. This hypothesis justifies the fact that mutations of TERT promoter preferentially occur in tissues that have low or no telomerase activity, such as the urothelium of the bladder [10,37,38]. In the urothelium of the bladder, it therefore seems plausible to assume that mutations of TERT promoter occur in proliferating cells that transiently activate telomerase in response to a damage-induced proliferative stimulus [39].