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Παρασκευή 12 Μαΐου 2017

Telomere length and pancreatic cancer risk: breaking down the evidence

Telomeres, located at the ends of chromosomes and composed of a protein complex and tandem repeats of TTAGGG nucleotides, function to protect chromosomes from end-to-end fusions, breakage and degradation in dividing cells. Due to the inherent nature of DNA replication ('the end replication problem') and oxidative stress—telomeres gradually shorten with age. This has been demonstrated cross-sectionally in most tissues examined including the pancreas, and especially in cells with extensive proliferation (eg, leucocytes).12 Cells with critically short telomeres enter growth arrest, or senescence, and may remain viable for extended periods. Premalignant cells can avoid senescence and continue to proliferate by upregulating telomerase or elongating telomeres by alternative mechanisms.1

Shortened telomeres are thought to contribute to chromosomal instability and age-related diseases in humans, including cancer. Up to 90% of human tumours reactivate telomerase, which is epigenetically silenced in most adult somatic cells.1...



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