We previously reported that the telomere-targeting drug telomestatin induces apoptosis accompanied by G-tail reduction and dissociation of binding protein TRF2 from telomeres in cancer cell lines but not normal or human telomerase reverse transcriptase (hTERT)-immortalized cells. Because telomere-targeting drugs induce growth arrest in normal cells at higher doses, their development is dependent on the ability to predict toxicity before in vivo use, but no models for this are available. Here, we established two new cell lines, telomerase immortalized human fetal hepatocytes, Hc3716-hTERT, and telomerase immortalized hepatic stellate cells, NPC-hTERT. Examinations showed that Hc3716-hTERT maintained normal mammalian cell morphology, cell growth, albumin expression, and wild-type p53 responsiveness, whereas NPC-hTERT maintained hepatic stellate-like morphology, expression of hepatic stellate markers, a-smooth muscle actin, and secretion of type I collagen, an extracellular matrix protein. Given our finding that telomere G-tail length in Hc3716 cells was decreased in senescence and increased by hTERT infection, we next examined the effect of high-dose telomestatin-induced telomere dysfunction and G-tail shortening on cellular functions in Hc3716-hTERT cells. Interestingly, telomestatin decreased expression of cytochrome P450 (CYP) family members CYP3A3 ⁄ 4, CYP3A5, and CYP3A7, mRNA and induced albumin expression at both mRNA and protein levels. These gene expression responses to telomestatin were similar to those of the normal parental cell Hc3716. These established cell lines thus represent the first model for predicting the side-effects of telomere-targeting drugs in normal cells, and should be powerful tools in the development of these drugs. (Cancer Sci 2010; 101: 1678-1685
BackgroundThe telomeric 3′-overhang (G-tail) length is essential for the biological effects of telomere dysfunction in vitro, but the association of length with aging and cardiovascular risk is unclear in humans. We investigated the association between the telomere G-tail length of leukocytes and cardiovascular risk, age-related white matter changes (ARWMCs), and endothelial function.MethodsPatients with a history of cerebrovascular disease and comorbidity were enrolled (n = 102; 69 males and 33 females, 70.1 ± 9.2 years). Total telomere and telomere G-tail lengths were measured using a hybridization protection assay. Endothelial function was evaluated by ultrasound assessment of brachial flow-mediated dilation (FMD).FindingsShortened telomere G-tail length was associated with age and Framingham risk score (P = 0.018 and P = 0.012). In addition, telomere G-tail length was positively correlated with FMD values (P = 0.031) and negatively with the severity of ARWMCs (P = 0.002). On multivariate regression analysis, telomere G-tail length was independently associated with FMD values (P = 0.022) and the severity of ARWMCs (P = 0.033), whereas total telomere length was not associated with these indicators.InterpretationTelomere G-tail length is associated with age and vascular risk factors, and might be superior to total telomere length as a marker of endothelial dysfunction and ARWMC severity.
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